diff --git a/INSTALL.openvpn b/INSTALL.openvpn
new file mode 100644
index 0000000..a5936b3
--- /dev/null
+++ b/INSTALL.openvpn
@@ -0,0 +1,368 @@
+Installation instructions for OpenVPN, a Secure Tunneling Daemon
+
+Copyright (C) 2002-2019 OpenVPN Inc. This program is free software;
+you can redistribute it and/or modify
+it under the terms of the GNU General Public License version 2
+as published by the Free Software Foundation.
+
+*************************************************************************
+
+QUICK START:
+
+  Unix:
+    ./configure && make && make install
+
+*************************************************************************
+
+To download OpenVPN source code of releases, go to:
+
+    https://openvpn.net/community-downloads/
+
+OpenVPN releases are also available as Debian/RPM packages:
+
+    https://community.openvpn.net/openvpn/wiki/OpenvpnSoftwareRepos
+
+OpenVPN development versions can be found here:
+
+   https://github.com/OpenVPN/openvpn
+   https://gitlab.com/OpenVPN/openvpn
+   https://sourceforge.net/p/openvpn/openvpn/ci/master/tree/
+
+They should all be in sync at any time.
+
+To download easy-rsa go to:
+
+    https://github.com/OpenVPN/easy-rsa
+
+To download tap-windows (NDIS 6) driver source code go to:
+
+    https://github.com/OpenVPN/tap-windows6
+
+To get the cross-compilation environment go to:
+
+    https://github.com/OpenVPN/openvpn-build
+
+For step-by-step instructions with real-world examples see:
+
+    https://community.openvpn.net/openvpn/wiki/GettingStartedwithOVPN
+    https://community.openvpn.net/openvpn/wiki
+    https://openvpn.net/community-resources/
+
+Also see the man page for more information.
+
+*************************************************************************
+
+SUPPORTED PLATFORMS:
+  (1) Linux (kernel 2.6+)
+  (2) Solaris
+  (3) OpenBSD 5.1+
+  (4) Mac OS X Darwin 10.5+
+  (5) FreeBSD 7.4+
+  (6) NetBSD 5.0+
+  (7) Windows Vista or later for OpenVPN 2.4
+  (8) Windows XP or later for OpenVPN 2.3
+
+SUPPORTED PROCESSOR ARCHITECTURES:
+   In general, OpenVPN is word size and endian independent, so
+   most processors should be supported.  Architectures known to
+   work include Intel x86, Alpha, Sparc, Amd64, and ARM.
+
+REQUIRES:
+  (1) TUN and/or TAP driver to allow user-space programs to control
+      a virtual point-to-point IP or Ethernet device.  See
+      TUN/TAP Driver Configuration section below for more info.
+
+OPTIONAL (but recommended):
+  (1) OpenSSL library, necessary for encryption, version 0.9.8 or higher
+      required, available from http://www.openssl.org/
+  (2) mbed TLS library, an alternative for encryption, version 2.0 or higher
+      required, available from https://tls.mbed.org/
+  (3) LZO real-time compression library, required for link compression,
+      available from http://www.oberhumer.com/opensource/lzo/
+      OpenBSD users can use ports or packages to install lzo, but remember
+      to add CFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib"
+      directives to "configure", since gcc will not find them otherwise.
+
+OPTIONAL (for developers only):
+  (1) Autoconf 2.59 or higher + Automake 1.9 or higher
+      -- available from http://www.gnu.org/software/software.html
+  (2) Dmalloc library
+      -- available from http://dmalloc.com/
+  (3) If using t_client.sh test framework, fping/fping6 is needed
+      -- Available from http://www.fping.org/
+      Note: t_client.sh needs an external configured OpenVPN server.
+      See t_client.rc-sample for more info.
+
+*************************************************************************
+
+CHECK OUT SOURCE FROM SOURCE REPOSITORY:
+
+  Clone the repository:
+
+    git clone https://github.com/OpenVPN/openvpn
+    git clone https://gitlab.com/OpenVPN/openvpn
+    git clone git://openvpn.git.sourceforge.net/gitroot/openvpn/openvpn
+
+  Check out stable version:
+
+    git checkout release/2.4
+
+  Check out master (unstable) branch:
+
+    git checkout master
+
+
+*************************************************************************
+
+BUILD COMMANDS FROM TARBALL:
+
+	./configure
+	make
+	make install
+
+*************************************************************************
+
+BUILD COMMANDS FROM SOURCE REPOSITORY CHECKOUT:
+
+	autoreconf -i -v -f
+	./configure
+	make
+	make install
+
+*************************************************************************
+
+BUILD A TARBALL FROM SOURCE REPOSITORY CHECKOUT:
+
+	autoreconf -i -v -f
+	./configure
+	make distcheck
+
+*************************************************************************
+
+TESTS (after BUILD):
+
+make check (Run all tests below)
+
+Test Crypto:
+
+./openvpn --genkey --secret key
+./openvpn --test-crypto --secret key
+
+Test SSL/TLS negotiations (runs for 2 minutes):
+
+./openvpn --config sample/sample-config-files/loopback-client (In one window)
+./openvpn --config sample/sample-config-files/loopback-server (Simultaneously in another window)
+
+For more thorough client-server tests you can configure your own, private test
+environment. See tests/t_client.rc-sample for details.
+
+*************************************************************************
+
+OPTIONS for ./configure:
+
+  --disable-lzo           disable LZO compression support [default=yes]
+  --disable-lz4           Disable LZ4 compression support
+  --enable-comp-stub      Don't compile compression support but still allow limited interoperability with compression-enabled peers
+  --disable-crypto        disable crypto support [default=yes]
+  --disable-ofb-cfb       disable support for OFB and CFB cipher modes
+                          [default=yes]
+  --enable-x509-alt-username
+                          enable the --x509-username-field feature
+                          [default=no]
+  --disable-server        disable server support only (but retain client
+                          support) [default=yes]
+  --disable-plugins       disable plug-in support [default=yes]
+  --disable-management    disable management server support [default=yes]
+  --enable-pkcs11         enable pkcs11 support [default=no]
+  --disable-fragment      disable internal fragmentation support (--fragment)
+                          [default=yes]
+  --disable-multihome     disable multi-homed UDP server support (--multihome)
+                          [default=yes]
+  --disable-port-share    disable TCP server port-share support (--port-share)
+                          [default=yes]
+  --disable-debug         disable debugging support (disable gremlin and verb
+                          7+ messages) [default=yes]
+  --enable-small          enable smaller executable size (disable OCC, usage
+                          message, and verb 4 parm list) [default=no]
+  --enable-iproute2       enable support for iproute2 [default=no]
+  --disable-def-auth      disable deferred authentication [default=yes]
+  --disable-pf            disable internal packet filter [default=yes]
+  --disable-plugin-auth-pam
+                          disable auth-pam plugin [default=platform specific]
+  --disable-plugin-down-root
+                          disable down-root plugin [default=platform specific]
+  --enable-pam-dlopen     dlopen libpam [default=no]
+  --enable-strict         enable strict compiler warnings (debugging option)
+                          [default=no]
+  --enable-pedantic       enable pedantic compiler warnings, will not generate
+                          a working executable (debugging option) [default=no]
+  --enable-werror         promote compiler warnings to errors, will cause
+                          builds to fail if the compiler issues warnings
+                          (debugging option) [default=no]
+  --enable-strict-options enable strict options check between peers (debugging
+                          option) [default=no]
+  --enable-selinux        enable SELinux support [default=no]
+  --enable-systemd        enable systemd support [default=no]
+  --enable-async-push     enable async-push support for plugins providing
+                          deferred authentication [default=no]
+
+ENVIRONMENT for ./configure:
+
+  PLUGINDIR   Path of plug-in directory [default=LIBDIR/openvpn/plugins]
+  IFCONFIG    full path to ipconfig utility
+  ROUTE       full path to route utility
+  IPROUTE     full path to ip utility
+  NETSTAT     path to netstat utility
+  MAN2HTML    path to man2html utility
+  GIT         path to git utility
+  SYSTEMD_ASK_PASSWORD
+              path to systemd-ask-password utility
+  SYSTEMD_UNIT_DIR
+              Path of systemd unit directory [default=LIBDIR/systemd/system]
+  TMPFILES_DIR
+              Path of tmpfiles directory [default=LIBDIR/tmpfiles.d]
+
+ENVIRONMENT variables adjusting parameters related to dependencies
+
+  TAP_CFLAGS  C compiler flags for tap
+  LIBPAM_CFLAGS
+              C compiler flags for libpam
+  LIBPAM_LIBS linker flags for libpam
+  PKCS11_HELPER_CFLAGS
+              C compiler flags for PKCS11_HELPER, overriding pkg-config
+  PKCS11_HELPER_LIBS
+              linker flags for PKCS11_HELPER, overriding pkg-config
+  OPENSSL_CFLAGS
+              C compiler flags for OpenSSL
+  OPENSSL_LIBS
+              linker flags for OpenSSL
+  MBEDTLS_CFLAGS
+              C compiler flags for mbedtls
+  MBEDTLS_LIBS
+              linker flags for mbedtls
+  LZO_CFLAGS  C compiler flags for lzo
+  LZO_LIBS    linker flags for lzo
+  LZ4_CFLAGS  C compiler flags for lz4
+  LZ4_LIBS    linker flags for lz4
+  libsystemd_CFLAGS
+              C compiler flags for libsystemd, overriding pkg-config
+  libsystemd_LIBS
+              linker flags for libsystemd, overriding pkg-config
+  P11KIT_CFLAGS
+              C compiler flags for P11KIT, overriding pkg-config
+  P11KIT_LIBS linker flags for P11KIT, overriding pkg-config
+
+*************************************************************************
+
+Linux distribution packaging:
+
+Each Linux distribution has their own way of doing packaging and their
+own set of guidelines of how proper packaging should be done.  It
+is therefore recommended to reach out to the Linux distributions you
+want to have OpenVPN packaged for directly.  The OpenVPN project wants
+to focus more on the OpenVPN development and less on the packaging
+and how packaging is done in all various distributions.
+
+For more details:
+
+* Arch Linux
+  https://www.archlinux.org/packages/?name=openvpn
+
+* Debian
+  https://packages.debian.org/search?keywords=openvpn&searchon=names
+  https://tracker.debian.org/pkg/openvpn
+
+* Fedora / Fedora EPEL (Red Hat Enterprise Linux/CentOS/Scientific Linux)
+  https://apps.fedoraproject.org/packages/openvpn/overview/
+  https://src.fedoraproject.org/rpms/openvpn
+
+* Gentoo
+  https://packages.gentoo.org/packages/net-vpn/openvpn
+  https://gitweb.gentoo.org/repo/gentoo.git/tree/net-vpn/openvpn
+
+* openSUSE
+  https://build.opensuse.org/package/show/network:vpn/openvpn
+
+* Ubuntu
+  https://packages.ubuntu.com/search?keywords=openvpn
+
+In addition, the OpenVPN community provides a best-effort APT repository
+for Debian and Ubuntu:
+https://community.openvpn.net/openvpn/wiki/OpenvpnSoftwareRepos
+
+*************************************************************************
+
+TUN/TAP Driver Configuration:
+
+* Linux 2.6 or higher (with integrated TUN/TAP driver):
+
+  (1) load driver:              modprobe tun
+  (2) enable routing:           echo 1 > /proc/sys/net/ipv4/ip_forward
+
+  Note that (1) needs to be done once per reboot.  If you install from RPM (see
+  above) and use the openvpn.init script, these steps are taken care of for you.
+
+* FreeBSD:
+
+  FreeBSD ships with the TUN/TAP driver, and the device nodes for tap0,
+  tap1, tap2, tap3, tun0, tun1, tun2 and tun3 are made by default.
+  However, only the TUN driver is linked into the GENERIC kernel.
+
+  To load the TAP driver, enter: 
+
+	kldload if_tap
+
+  See man rc(8) to find out how you can do this at boot time.
+
+  The easiest way is to install OpenVPN from the FreeBSD ports system,
+  the port includes a sample script to automatically load the TAP driver
+  at boot-up time.
+
+* OpenBSD:
+
+  OpenBSD has dynamically created tun* devices so you only need
+  to create an empty /etc/hostname.tun0 (tun1, tun2 and so on) for each tun
+  you plan to use to create the device(s) at boot.
+
+* Solaris:
+
+  You need a TUN/TAP kernel driver for OpenVPN to work:
+
+    http://www.whiteboard.ne.jp/~admin2/tuntap/
+
+* Windows
+
+  OpenVPN on Windows needs a TUN/TAP kernel driver to work. OpenVPN installers
+  include this driver, so installing it separately is not usually required.
+  Windows XP/2003 must use the NDIS 5 (tap-windows) driver, whereas on more
+  recent Windows versions it is recommended to use the NDIS 6 driver
+  (tap-windows6) instead.
+
+*************************************************************************
+
+CAVEATS & BUGS:
+
+* I have noticed cases where TCP sessions tunneled over the Linux
+  TAP driver (kernel 2.4.21 and 2.4.22) stall when lower --mssfix
+  values are used.  The TCP sessions appear to unstall and resume
+  normally when the remote VPN endpoint is pinged.
+
+* If run through a firewall using OpenBSDs packet filter PF and the
+  filter rules include a "scrub" directive, you may get problems talking
+  to Linux hosts over the tunnel, since the scrubbing will kill packets
+  sent from Linux hosts if they are fragmented. This is usually seen as
+  tunnels where small packets and pings get through but large packets
+  and "regular traffic" don't. To circumvent this, add "no-df" to
+  the scrub directive so that the packet filter will let fragments with
+  the "dont fragment"-flag set through anyway.
+
+* Mixing OFB or CFB cipher modes with static key mode is not recommended,
+  and is flagged as an error on OpenVPN versions 1.2.1 and greater.
+  If you use the --cipher option to explicitly select an OFB or CFB
+  cipher AND you are using static key mode, it is possible that there
+  could be an IV collision if the OpenVPN daemons on both sides
+  of the connection are started at exactly the same time, since
+  OpenVPN uses a timestamp combined with a sequence number as the cipher
+  IV for OFB and CFB modes.  This is not an issue if you are
+  using CBC cipher mode (the default), or if you are using OFB or CFB
+  cipher mode with SSL/TLS authentication.
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..769ac15
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,1027 @@
+BEGIN COPYING
+
+OpenVPN (TM) -- An Open Source VPN daemon
+
+Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+
+This distribution contains multiple components, some
+of which fall under different licenses.  By using OpenVPN
+or any of the bundled components enumerated below, you
+agree to be bound by the conditions of the license for
+each respective component.
+
+OpenVPN trademark
+-----------------
+
+  "OpenVPN" is a trademark of OpenVPN Inc
+
+
+OpenVPN license:
+----------------
+
+  OpenVPN is distributed under the GPL license version 2 (see Below).
+
+  Special exception for linking OpenVPN with OpenSSL:
+
+  In addition, as a special exception, OpenVPN Inc gives
+  permission to link the code of this program with the OpenSSL
+  library (or with modified versions of OpenSSL that use the same
+  license as OpenSSL), and distribute linked combinations including
+  the two.  You must obey the GNU General Public License in all
+  respects for all of the code used other than OpenSSL.  If you modify
+  this file, you may extend this exception to your version of the
+  file, but you are not obligated to do so.  If you do not wish to
+  do so, delete this exception statement from your version.
+
+LZO license:
+------------
+
+  LZO is Copyright (C) Markus F.X.J. Oberhumer,
+  and is licensed under the GPL.
+
+  Special exception for linking OpenVPN with both OpenSSL and LZO:
+
+  Hereby I grant a special exception to the OpenVPN project 
+  (http://openvpn.net/) to link the LZO library with 
+  the OpenSSL library (http://www.openssl.org).
+ 
+  Markus F.X.J. Oberhumer
+
+TAP-Win32/TAP-Win64 Driver license:
+-----------------------------------
+
+  This device driver was inspired by the CIPE-Win32 driver by
+  Damion K. Wilson.
+
+  The source and object code of the TAP-Win32/TAP-Win64 driver
+  is Copyright (C) 2002-2018 OpenVPN Inc, and is released under
+  the GPL version 2.
+
+Windows DDK Samples:
+--------------------
+
+  The Windows binary distribution includes devcon.exe, a
+  Microsoft DDK sample which is redistributed under the terms
+  of the DDK EULA.
+
+NSIS License:
+-------------
+
+  Copyright (C) 2002-2003 Joost Verburg
+
+  This software is provided 'as-is', without any express or implied
+  warranty. In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute
+  it freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; 
+     you must not claim that you wrote the original software.
+     If you use this software in a product, an acknowledgment in the
+     product documentation would be appreciated but is not required.
+  2. Altered versions must be plainly marked as such,
+     and must not be misrepresented as being the original software.
+  3. This notice may not be removed or altered from any distribution.
+
+OpenSSL License:
+----------------
+
+  The OpenSSL toolkit stays under a dual license, i.e. both the conditions of
+  the OpenSSL License and the original SSLeay license apply to the toolkit.
+  See below for the actual license texts. Actually both licenses are BSD-style
+  Open Source licenses. In case of any license issues related to OpenSSL
+  please contact openssl-core@openssl.org.
+
+/* ====================================================================
+ * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer. 
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com).  This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
+
+ Original SSLeay License
+ -----------------------
+
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
+ * All rights reserved.
+ *
+ * This package is an SSL implementation written
+ * by Eric Young (eay@cryptsoft.com).
+ * The implementation was written so as to conform with Netscapes SSL.
+ * 
+ * This library is free for commercial and non-commercial use as long as
+ * the following conditions are aheared to.  The following conditions
+ * apply to all code found in this distribution, be it the RC4, RSA,
+ * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
+ * included with this distribution is covered by the same copyright terms
+ * except that the holder is Tim Hudson (tjh@cryptsoft.com).
+ * 
+ * Copyright remains Eric Young's, and as such any Copyright notices in
+ * the code are not to be removed.
+ * If this package is used in a product, Eric Young should be given attribution
+ * as the author of the parts of the library used.
+ * This can be in the form of a textual message at program startup or
+ * in documentation (online or textual) provided with the package.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *    "This product includes cryptographic software written by
+ *     Eric Young (eay@cryptsoft.com)"
+ *    The word 'cryptographic' can be left out if the rouines from the library
+ *    being used are not cryptographic related :-).
+ * 4. If you include any Windows specific code (or a derivative thereof) from 
+ *    the apps directory (application code) you must include an acknowledgement:
+ *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
+ * 
+ * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ * 
+ * The licence and distribution terms for any publically available version or
+ * derivative of this code cannot be changed.  i.e. this code cannot simply be
+ * copied and put under another distribution licence
+ * [including the GNU Public Licence.]
+ */
+
+GNU Public License (GPL)
+------------------------
+
+  OpenVPN, LZO, and the TAP-Win32 distributions are
+  licensed under the GPL version 2 (see COPYRIGHT.GPL).
+
+  In the Windows binary distribution of OpenVPN, the
+  GPL is reproduced below.
+
+
+
+END COPYING
+
+------------------
+
+BEGIN COPYRIGHT.GPL
+
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License version 2
+    as published by the Free Software Foundation.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
+
+
+END COPYRIGHT.GPL
+
+------------------
+
+BSD 3-Clause License:
+-----------------
+
+/*
+ * Redistribution and use in source and binary forms, with or without modifi-
+ * cation, are permitted provided that the following conditions are met:
+ *
+ *   o  Redistributions of source code must retain the above copyright notice,
+ *      this list of conditions and the following disclaimer.
+ *
+ *   o  Redistributions in binary form must reproduce the above copyright no-
+ *      tice, this list of conditions and the following disclaimer in the do-
+ *      cumentation and/or other materials provided with the distribution.
+ *
+ *   o  The names of the contributors may not be used to endorse or promote
+ *      products derived from this software without specific prior written
+ *      permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LI-
+ * ABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUEN-
+ * TIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEV-
+ * ER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABI-
+ * LITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+------------------
+src/compat/compat-lz4.c
+
+/*
+   LZ4 - Fast LZ compression algorithm
+   Copyright (C) 2011-present, Yann Collet.
+
+   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+   You can contact the author at :
+    - LZ4 homepage : http://www.lz4.org
+    - LZ4 source repository : https://github.com/lz4/lz4
+*/
+
+------------------
+m4/pkg.m4
+
+# Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# As a special exception to the GNU General Public License, if you
+# distribute this file as part of a program that contains a
+# configuration script generated by Autoconf, you may include it under
+# the same distribution terms that you use for the rest of that program.
+
+       GNU General Public License v2.0 w/Autoconf exception
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+                            NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License version 2
+    as published by the Free Software Foundation.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) year name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
+
+Autoconf Exception
+
+As a special exception, the Free Software Foundation gives unlimited permission
+to copy, distribute and modify the configure scripts that are the output of
+Autoconf. You need not follow the terms of the GNU General Public License
+when using or distributing such scripts, even though portions of the text
+of Autoconf appear in them. The GNU General Public License (GPL) does govern
+all other use of the material that constitutes the Autoconf program.
+
+Certain portions of the Autoconf source text are designed to be copied (in
+certain cases, depending on the input) into the output of Autoconf. We call
+these the "data" portions. The rest of the Autoconf source text consists of
+comments plus executable code that decides which of the data portions to output
+in any given case. We call these comments and executable code the "non-data"
+portions. Autoconf never copies any of the non-data portions into its output.
+
+This special exception to the GPL applies to versions of Autoconf released
+by the Free Software Foundation. When you make and distribute a modified version
+of Autoconf, you may extend this special exception to the GPL to apply to
+your modified version as well, *unless* your modified version has the potential
+to copy into its output some of the text that was the non-data portion of
+the version that you started with. (In other words, unless your change moves
+or copies text from the non-data portions to the data portions.) If your modification
+has such potential, you must delete any notice of this special exception to
+the GPL from your modified version.
diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 0000000..753c526
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1,86 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2010      David Sommerseth <dazo@users.sourceforge.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+#  This program is free software; you can redistribute it and/or modify
+#  it under the terms of the GNU General Public License version 2
+#  as published by the Free Software Foundation.
+#
+#  This program is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#  GNU General Public License for more details.
+#
+#  You should have received a copy of the GNU General Public License along
+#  with this program; if not, write to the Free Software Foundation, Inc.,
+#  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+
+# This option prevents autoreconf from overriding our COPYING and
+# INSTALL targets:
+AUTOMAKE_OPTIONS = foreign 1.9
+ACLOCAL_AMFLAGS = -I m4
+
+MAINTAINERCLEANFILES = \
+	config.log config.status \
+	$(srcdir)/Makefile.in \
+	$(srcdir)/config.h.in $(srcdir)/config.h.in~ $(srcdir)/configure \
+	$(srcdir)/install-sh $(srcdir)/ltmain.sh $(srcdir)/missing \
+	$(srcdir)/m4/libtool.m4 $(srcdir)/m4/lt~obsolete.m4 \
+	$(srcdir)/m4/ltoptions.m4 $(srcdir)/m4/ltsugar.m4 \
+	$(srcdir)/m4/ltversion.m4 \
+	$(srcdir)/depcomp $(srcdir)/aclocal.m4 \
+	$(srcdir)/config.guess $(srcdir)/config.sub
+
+CLEANFILES = \
+	config-version.h tests/t_client.sh
+
+EXTRA_DIST = \
+	contrib \
+	debug
+
+.PHONY: config-version.h
+
+if GIT_CHECKOUT
+BUILT_SOURCES = \
+	config-version.h
+endif
+
+SUBDIRS = include src
+
+dist_doc_DATA = \
+	README.IPv6
+	LICENSE
+
+dist_noinst_DATA = \
+	README.IPv6
+
+dist_noinst_HEADERS = \
+	config-msvc.h \
+	config-msvc-version.h.in
+
+if WIN32
+rootdir=$(prefix)
+root_DATA = version.sh
+endif
+
+config-version.h:
+	@CONFIGURE_GIT_CHFILES="`GIT_DIR=\"$(top_srcdir)/.git\" $(GIT) diff-files --name-status -r --ignore-submodules --quiet -- || echo \"+\"`"; \
+	CONFIGURE_GIT_UNCOMMITTED="`GIT_DIR=\"$(top_srcdir)/.git\" $(GIT) diff-index --cached  --quiet --ignore-submodules HEAD || echo \"*\"`"; \
+	CONFIGURE_GIT_REVISION="`GIT_DIR=\"$(top_srcdir)/.git\" $(GIT) rev-parse --symbolic-full-name HEAD | cut -d/ -f3-`/`GIT_DIR=\"$(top_srcdir)/.git\" $(GIT) rev-parse --short=16 HEAD`"; \
+	echo "#define CONFIGURE_GIT_REVISION \"$${CONFIGURE_GIT_REVISION}\"" > config-version.h.tmp; \
+	echo "#define CONFIGURE_GIT_FLAGS \"$${CONFIGURE_GIT_CHFILES}$${CONFIGURE_GIT_UNCOMMITTED}\"" >> config-version.h.tmp
+
+	@if ! [ -f config-version.h ] || ! cmp -s config-version.h.tmp config-version.h; then \
+		echo "replacing config-version.h"; \
+		mv config-version.h.tmp config-version.h; \
+	else \
+		rm -f config-version.h.tmp; \
+	fi
diff --git a/README.IPv6 b/README.IPv6
new file mode 100644
index 0000000..18068fe
--- /dev/null
+++ b/README.IPv6
@@ -0,0 +1,56 @@
+Since 2.3.0, OpenVPN officially supports IPv6, and all widely used
+patches floating around for older versions have been integrated.
+
+IPv6 payload support
+--------------------
+
+This is for "IPv6 inside OpenVPN", with server-pushed IPv6 configuration
+on the client, and support for IPv6 configuration on the tun/tap interface
+from within the openvpn config.
+
+The code in 2.3.0 supersedes the IPv6 payload patches from Gert Doering,
+formerly located at http://www.greenie.net/ipv6/openvpn.html
+
+
+The following options have been added to handle IPv6 configuration,
+analogous to their IPv4 counterparts (--server <-> --server-ipv6, etc.)
+
+     - server-ipv6
+     - ifconfig-ipv6
+     - ifconfig-ipv6-pool
+     - ifconfig-ipv6-push
+     - route-ipv6
+     - iroute-ipv6
+
+see "man openvpn" for details how they are used.
+
+
+
+IPv6 transport support
+----------------------
+
+This is to enable OpenVPN peers or client/servers to talk to each other
+over an IPv6 network ("OpenVPN over IPv6").
+
+The code in 2.3.0 supersedes the IPv6 transport patches from JuanJo Ciarlante,
+formerly located at http://github.com/jjo/openvpn-ipv6
+
+OpenVPN 2.4.0 includes a big overhaul of the IPv6 transport patches
+originally implemented for the Android client (ics-openvpn)
+
+IPv4/IPv6 transport is automatically is selected when resolving addresses.
+Use a 6 or 4 suffix to force IPv6/IPv4:
+
+  --proto udp6
+  --proto tcp4
+  --proto tcp6-client
+  --proto tcp4-server
+  --proto tcp6 --client / --proto tcp6 --server
+
+On systems that allow IPv4 connections on IPv6 sockets
+(all systems supporting IPV6_V6ONLY setsockopt), an OpenVPN server can
+handle IPv4 connections on the IPv6 socket as well, making it a true
+dual-stacked server. Use bind ipv6only to disable this behaviour.
+
+On other systems, as of 2.3.0, you need to run separate server instances
+for IPv4 and IPv6.
diff --git a/README.ec b/README.ec
new file mode 100644
index 0000000..3293801
--- /dev/null
+++ b/README.ec
@@ -0,0 +1,35 @@
+Since 2.4.0, OpenVPN has official support for elliptic curve crypto. Elliptic
+curves are an alternative to RSA for asymmetric encryption.
+
+Elliptic curve crypto ('ECC') can be used for the ('TLS') control channel only
+in OpenVPN; the data channel (encrypting the actual network traffic) uses
+symmetric encryption. ECC can be used in TLS for authentication (ECDSA) and key
+exchange (ECDH).
+
+Key exchange (ECDH)
+-------------------
+OpenVPN 2.4.0 and newer automatically initialize ECDH parameters. When ECDSA is
+used for authentication, the curve used for the server certificate will be used
+for ECDH too. When autodetection fails (e.g. when using RSA certificates)
+OpenVPN lets the crypto library decide if possible, or falls back to the
+secp384r1 curve.
+
+An administrator can force an OpenVPN/OpenSSL server to use a specific curve
+using the --ecdh-curve <curvename> option with one of the curves listed as
+available by the --show-curves option. Clients will use the same curve as
+selected by the server.
+
+Note that not all curves listed by --show-curves are available for use with TLS;
+in that case connecting will fail with a 'no shared cipher' TLS error.
+
+Authentication (ECDSA)
+----------------------
+Since OpenVPN 2.4.0, using ECDSA certificates works 'out of the box'. Which
+specific curves and cipher suites are available depends on your version and
+configuration of the crypto library. The crypto library will automatically
+select a cipher suite for the TLS control channel.
+
+Support for generating an ECDSA certificate chain is available in EasyRSA (in
+spite of it's name) since EasyRSA 3.0. The parameters you're looking for are
+'--use-algo=ec' and '--curve=<curve_name>'. See the EasyRSA documentation for
+more details on generating ECDSA certificates.
diff --git a/README.openvpn b/README.openvpn
new file mode 100644
index 0000000..b75a568
--- /dev/null
+++ b/README.openvpn
@@ -0,0 +1,74 @@
+OpenVPN -- A Secure tunneling daemon
+
+Copyright (C) 2002-2018 OpenVPN Inc. This program is free software;
+you can redistribute it and/or modify
+it under the terms of the GNU General Public License version 2
+as published by the Free Software Foundation.
+
+*************************************************************************
+
+To get the latest release of OpenVPN, go to:
+
+	https://openvpn.net/index.php/download/community-downloads.html
+
+To Build and Install,
+
+	tar -zxf openvpn-<version>.tar.gz
+	cd openvpn-<version>
+	./configure
+	make
+	make install
+
+or see the file INSTALL for more info.
+
+*************************************************************************
+
+For detailed information on OpenVPN, including examples, see the man page
+  http://openvpn.net/man.html
+
+For a sample VPN configuration, see
+  http://openvpn.net/howto.html
+
+To report an issue, see
+  https://community.openvpn.net/openvpn/report
+
+For a description of OpenVPN's underlying protocol,
+  see the file ssl.h included in the source distribution.
+
+*************************************************************************
+
+Other Files & Directories:
+
+* configure.ac -- script to rebuild our configure
+  script and makefile.
+
+* sample/sample-scripts/verify-cn
+
+  A sample perl script which can be used with OpenVPN's
+  --tls-verify option to provide a customized authentication
+  test on embedded X509 certificate fields.
+
+* sample/sample-keys/
+
+  Sample RSA keys and certificates.  DON'T USE THESE FILES
+  FOR ANYTHING OTHER THAN TESTING BECAUSE THEY ARE TOTALLY INSECURE.
+
+* sample/sample-config-files/
+
+  A collection of OpenVPN config files and scripts from
+  the HOWTO at http://openvpn.net/howto.html
+
+*************************************************************************
+
+Note that easy-rsa and tap-windows are now maintained in their own subprojects.
+Their source code is available here:
+
+  https://github.com/OpenVPN/easy-rsa
+  https://github.com/OpenVPN/tap-windows
+
+The old cross-compilation environment (domake-win) and the Python-based
+buildsystem have been replaced with openvpn-build:
+
+  https://github.com/OpenVPN/openvpn-build
+
+See the INSTALL file for usage information.
diff --git a/compat.m4 b/compat.m4
new file mode 100644
index 0000000..e54a720
--- /dev/null
+++ b/compat.m4
@@ -0,0 +1,74 @@
+dnl  OpenVPN -- An application to securely tunnel IP networks
+dnl             over a single UDP port, with support for SSL/TLS-based
+dnl             session authentication and key exchange,
+dnl             packet encryption, packet authentication, and
+dnl             packet compression.
+dnl
+dnl  Copyright (C) 2008-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+dnl
+dnl  This program is free software; you can redistribute it and/or modify
+dnl  it under the terms of the GNU General Public License as published by
+dnl  the Free Software Foundation; either version 2 of the License, or
+dnl  (at your option) any later version.
+dnl
+dnl  This program is distributed in the hope that it will be useful,
+dnl  but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl  GNU General Public License for more details.
+dnl
+dnl  You should have received a copy of the GNU General Public License along
+dnl  with this program; if not, write to the Free Software Foundation, Inc.,
+dnl  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+dnl Compatibility layer for <autoconf-2.60 <automake-1.10
+dnl REMOVE THIS IN FUTURE!
+
+ifdef(
+	[AS_VAR_IF],
+	,
+	[
+		AC_DEFUN([AS_VAR_IF], [dnl
+			if test "$$1" = "$2"; then
+				m4_ifval([$3], [$3], [:])
+			else
+				m4_ifval([$4], [$4], [:])
+			fi
+		])
+	]
+)
+ifdef(
+	[AC_USE_SYSTEM_EXTENSIONS],
+	,
+	[AC_DEFUN([AC_USE_SYSTEM_EXTENSIONS], [GNU_SOURCE])]
+)
+ifdef(
+	[AC_PROG_SED],
+	,
+	[AC_DEFUN([AC_PROG_SED], [AC_CHECK_PROGS([SED], [sed])])]
+)
+ifdef(
+	[AC_TYPE_INT8_T],
+	,
+	[
+		AC_CHECK_HEADERS([inttypes.h stdint.h])
+		test -z "${ac_cv_header_inttypes_h}${ac_cv_header_stdint_h}" && \
+			AC_MSG_ERROR([Required inttypes.h stdint.h not found])
+		
+		AC_DEFUN([AC_TYPE_INT8_T], [])
+		AC_DEFUN([AC_TYPE_INT16_T], [])
+		AC_DEFUN([AC_TYPE_INT32_T], [])
+		AC_DEFUN([AC_TYPE_INT64_T], [])
+		AC_DEFUN([AC_TYPE_UINT8_T], [])
+		AC_DEFUN([AC_TYPE_UINT16_T], [])
+		AC_DEFUN([AC_TYPE_UINT32_T], [])
+		AC_DEFUN([AC_TYPE_UINT64_T], [])
+	]
+)
+if test -z "${docdir}"; then
+	docdir="\$(datadir)/doc/\$(PACKAGE_NAME)"
+	AC_SUBST([docdir])
+fi
+if test -z "${htmldir}"; then
+	htmldir="\$(docdir)"
+	AC_SUBST([htmldir])
+fi
diff --git a/config-msvc-version.h.in b/config-msvc-version.h.in
new file mode 100644
index 0000000..7977cb8
--- /dev/null
+++ b/config-msvc-version.h.in
@@ -0,0 +1,14 @@
+#define PACKAGE_NAME "@PRODUCT_NAME@"
+#define PACKAGE_STRING "@PRODUCT_NAME@ @PRODUCT_VERSION_MAJOR@.@PRODUCT_VERSION_MINOR@@PRODUCT_VERSION_PATCH@"
+#define PACKAGE_TARNAME "@PRODUCT_TARNAME@"
+#define PACKAGE "@PRODUCT_TARNAME@"
+#define PRODUCT_VERSION_MAJOR "@PRODUCT_VERSION_MAJOR@"
+#define PRODUCT_VERSION_MINOR "@PRODUCT_VERSION_MINOR@"
+#define PRODUCT_VERSION_PATCH "@PRODUCT_VERSION_PATCH@"
+#define PACKAGE_VERSION "@PRODUCT_VERSION_MAJOR@.@PRODUCT_VERSION_MINOR@.@PRODUCT_VERSION_PATCH@"
+#define PRODUCT_VERSION "@PRODUCT_VERSION_MAJOR@.@PRODUCT_VERSION_MINOR@.@PRODUCT_VERSION_PATCH@"
+#define PRODUCT_BUGREPORT "@PRODUCT_BUGREPORT@"
+#define OPENVPN_VERSION_RESOURCE @PRODUCT_VERSION_RESOURCE@
+#define TAP_WIN_COMPONENT_ID "@PRODUCT_TAP_WIN_COMPONENT_ID@"
+#define TAP_WIN_MIN_MAJOR @PRODUCT_TAP_WIN_MIN_MAJOR@
+#define TAP_WIN_MIN_MINOR @PRODUCT_TAP_WIN_MIN_MINOR@
diff --git a/config-msvc.h b/config-msvc.h
new file mode 100644
index 0000000..0bb153d
--- /dev/null
+++ b/config-msvc.h
@@ -0,0 +1,138 @@
+#include <config-msvc-version.h>
+
+#define CONFIGURE_DEFINES "N/A"
+
+#define ENABLE_DEF_AUTH 1
+#define ENABLE_PF 1
+#define ENABLE_CRYPTO 1
+#define ENABLE_CRYPTO_OPENSSL 1
+#define ENABLE_DEBUG 1
+#define ENABLE_EUREPHIA 1
+#define ENABLE_FRAGMENT 1
+#define ENABLE_HTTP_PROXY 1
+#define ENABLE_LZO 1
+#define ENABLE_LZ4 1
+#define NEED_COMPAT_LZ4 1
+#define ENABLE_MANAGEMENT 1
+#define ENABLE_MULTIHOME 1
+#define ENABLE_PKCS11 1
+#define ENABLE_PLUGIN 1
+#define ENABLE_PORT_SHARE 1
+#define ENABLE_SOCKS 1
+
+#define HAVE_ERRNO_H 1
+#define HAVE_FCNTL_H 1
+#define HAVE_CTYPE_H 1
+#define HAVE_STDARG_H 1
+#define HAVE_STDIO_H 1
+#define HAVE_STDLIB_H 1
+#define HAVE_STRDUP 1
+#define HAVE_STRERROR 1
+#define HAVE_STRINGS_H 1
+#define HAVE_STRING_H 1
+#define HAVE_LIMITS_H 1
+#define HAVE_SYSTEM 1
+#define HAVE_TIME 1
+#define HAVE_TIME_H 1
+#define HAVE_UNLINK 1
+#define HAVE_VSNPRINTF 1
+#define HAVE_WINDOWS_H 1
+#define HAVE_WINSOCK2_H 1
+#define HAVE_WS2TCPIP_H 1
+#define HAVE_IO_H 1
+#define HAVE_DIRECT_H 1
+#define HAVE_SYS_TYPES_H 1
+#define HAVE_SYS_STAT_H 1
+#define HAVE_LZO_LZO1X_H 1
+#define HAVE_LZO_LZOUTIL_H 1
+#define HAVE_VERSIONHELPERS_H 1
+
+#define HAVE_ACCESS 1
+#define HAVE_CHDIR 1
+#define HAVE_CHSIZE 1
+#define HAVE_CPP_VARARG_MACRO_ISO 1
+#define HAVE_CTIME 1
+#define HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH 1
+#define HAVE_IN_PKTINFO 1
+#define HAVE_MEMSET 1
+#define HAVE_PUTENV 1
+#define HAVE_STAT 1
+
+#define HAVE_SOCKET 1
+#define HAVE_RECV 1
+#define HAVE_RECVFROM 1
+#define HAVE_SEND 1
+#define HAVE_SENDTO 1
+#define HAVE_LISTEN 1
+#define HAVE_ACCEPT 1
+#define HAVE_CONNECT 1
+#define HAVE_BIND 1
+#define HAVE_SELECT 1
+#define HAVE_GETHOSTBYNAME 1
+#define HAVE_INET_NTOA 1
+#define HAVE_SETSOCKOPT 1
+#define HAVE_GETSOCKOPT 1
+#define HAVE_GETSOCKNAME 1
+#define HAVE_POLL 1
+
+#define HAVE_OPENSSL_ENGINE 1
+
+#define PATH_SEPARATOR     '\\'
+#define PATH_SEPARATOR_STR "\\"
+
+#ifndef __cplusplus
+#define inline __inline
+#endif
+
+#define EMPTY_ARRAY_SIZE 0
+#define TARGET_WIN32 1
+#define TARGET_ALIAS "Windows-MSVC"
+
+#define HAVE_DECL_SO_MARK 0
+
+#define strncasecmp strnicmp
+#define strcasecmp _stricmp
+
+#if _MSC_VER<1900
+#define snprintf _snprintf
+#endif
+
+#if _MSC_VER < 1800
+#define strtoull strtoul
+#endif
+
+#define in_addr_t uint32_t
+#define ssize_t SSIZE_T
+
+#define S_IRUSR 0
+#define S_IWUSR 0
+#define R_OK 4
+#define W_OK 2
+#define X_OK 1
+#define F_OK 0
+
+#define SIGHUP    1
+#define SIGINT    2
+#define SIGUSR1   10
+#define SIGUSR2   12
+#define SIGTERM   15
+
+typedef unsigned __int64 uint64_t;
+typedef unsigned __int32 uint32_t;
+typedef unsigned __int16 uint16_t;
+typedef unsigned __int8 uint8_t;
+typedef __int64 int64_t;
+typedef __int32 int32_t;
+typedef __int16 int16_t;
+typedef __int8 int8_t;
+typedef uint16_t in_port_t;
+
+#ifdef HAVE_CONFIG_MSVC_LOCAL_H
+#include <config-msvc-local.h>
+#endif
+
+/* Vista and above has implementation of inet_ntop / inet_pton */
+#if _WIN32_WINNT >= _WIN32_WINNT_VISTA
+    #define HAVE_INET_NTOP
+    #define HAVE_INET_PTON
+#endif
diff --git a/config.h b/config.h
new file mode 100644
index 0000000..14ccd59
--- /dev/null
+++ b/config.h
@@ -0,0 +1,969 @@
+/* config.h.  Generated from config.h.in by configure.  */
+/* config.h.in.  Generated from configure.ac by autoheader.  */
+
+/* Configuration settings */
+#define CONFIGURE_DEFINES "enable_async_push=no enable_comp_stub=no enable_crypto=yes enable_crypto_ofb_cfb=yes enable_debug=yes enable_def_auth=yes enable_dlopen=unknown enable_dlopen_self=unknown enable_dlopen_self_static=unknown enable_fast_install=needless enable_fragment=yes enable_iproute2=no enable_libtool_lock=yes enable_lz4=no enable_lzo=yes enable_management=yes enable_multihome=yes enable_pam_dlopen=no enable_pedantic=no enable_pf=yes enable_pkcs11=no enable_plugin_auth_pam=no enable_plugin_down_root=yes enable_plugins=yes enable_port_share=yes enable_selinux=no enable_server=yes enable_shared=yes enable_shared_with_static_runtimes=no enable_small=no enable_static=yes enable_strict=no enable_strict_options=no enable_systemd=no enable_werror=no enable_win32_dll=yes enable_x509_alt_username=no with_aix_soname=aix with_crypto_library=openssl with_gnu_ld=yes with_mem_check=no with_sysroot=no"
+
+/* special build string */
+/* #undef CONFIGURE_SPECIAL_BUILD */
+
+/* Use memory debugging function in OpenSSL */
+/* #undef CRYPTO_MDEBUG */
+
+/* p11-kit proxy */
+/* #undef DEFAULT_PKCS11_MODULE */
+
+/* Use dmalloc memory debugging library */
+/* #undef DMALLOC */
+
+/* Dimension to use for empty array declaration */
+#define EMPTY_ARRAY_SIZE 0
+
+/* Enable async push */
+/* #undef ENABLE_ASYNC_PUSH */
+
+/* Enable client capability only */
+/* #undef ENABLE_CLIENT_ONLY */
+
+/* Enable compression stub capability */
+/* #undef ENABLE_COMP_STUB */
+
+/* Enable crypto library */
+#define ENABLE_CRYPTO 1
+
+/* Use mbed TLS library */
+/* #undef ENABLE_CRYPTO_MBEDTLS */
+
+/* Use OpenSSL library */
+#define ENABLE_CRYPTO_OPENSSL 1
+
+/* Enable debugging support */
+#define ENABLE_DEBUG 1
+
+/* Enable deferred authentication */
+#define ENABLE_DEF_AUTH 1
+
+/* We have persist tun capability */
+#define ENABLE_FEATURE_TUN_PERSIST 1
+
+/* Enable internal fragmentation support */
+#define ENABLE_FRAGMENT 1
+
+/* enable iproute2 support */
+/* #undef ENABLE_IPROUTE */
+
+/* Enable LZ4 compression library */
+/* #undef ENABLE_LZ4 */
+
+/* Enable LZO compression library */
+#define ENABLE_LZO 1
+
+/* Enable management server capability */
+#define ENABLE_MANAGEMENT 1
+
+/* Enable multi-homed UDP server capability */
+#define ENABLE_MULTIHOME 1
+
+/* Enable OFB and CFB cipher modes */
+#define ENABLE_OFB_CFB_MODE 1
+
+/* Enable internal packet filter */
+#define ENABLE_PF 1
+
+/* Enable PKCS11 */
+/* #undef ENABLE_PKCS11 */
+
+/* Enable plug-in support */
+#define ENABLE_PLUGIN 1
+
+/* Enable TCP Server port sharing */
+#define ENABLE_PORT_SHARE 1
+
+/* SELinux support */
+/* #undef ENABLE_SELINUX */
+
+/* Enable smaller executable size */
+/* #undef ENABLE_SMALL */
+
+/* Enable strict options check between peers */
+/* #undef ENABLE_STRICT_OPTIONS_CHECK */
+
+/* Enable systemd integration */
+/* #undef ENABLE_SYSTEMD */
+
+/* Enable --x509-username-field feature */
+/* #undef ENABLE_X509ALTUSERNAME */
+
+/* Define to 1 if you have the `accept' function. */
+#define HAVE_ACCEPT 1
+
+/* Define to 1 if you have the `access' function. */
+#define HAVE_ACCESS 1
+
+/* Use crypto library */
+#define HAVE_AEAD_CIPHER_MODES 1
+
+/* Compiler supports anonymous unions */
+#define HAVE_ANONYMOUS_UNION_SUPPORT /**/
+
+/* Define to 1 if you have the <arpa/inet.h> header file. */
+#define HAVE_ARPA_INET_H 1
+
+/* Define to 1 if you have the `basename' function. */
+#define HAVE_BASENAME 1
+
+/* Define to 1 if you have the `bind' function. */
+#define HAVE_BIND 1
+
+/* Define to 1 if you have the `chdir' function. */
+#define HAVE_CHDIR 1
+
+/* Define to 1 if you have the `chroot' function. */
+#define HAVE_CHROOT 1
+
+/* Define to 1 if you have the `chsize' function. */
+/* #undef HAVE_CHSIZE */
+
+/* struct cmsghdr needed for extended socket error support */
+#define HAVE_CMSGHDR 1
+
+/* extra version available in config-version.h */
+/* #undef HAVE_CONFIG_VERSION_H */
+
+/* Define to 1 if you have the `connect' function. */
+#define HAVE_CONNECT 1
+
+/* Define to 1 if your compiler supports GNU GCC-style variadic macros */
+#define HAVE_CPP_VARARG_MACRO_GCC 1
+
+/* Define to 1 if your compiler supports ISO C99 variadic macros */
+#define HAVE_CPP_VARARG_MACRO_ISO 1
+
+/* Define to 1 if you have the `ctime' function. */
+#define HAVE_CTIME 1
+
+/* Define to 1 if you have the <ctype.h> header file. */
+#define HAVE_CTYPE_H 1
+
+/* Define to 1 if you have the `daemon' function. */
+#define HAVE_DAEMON 1
+
+/* Define to 1 if you have the declaration of `SIGHUP', and to 0 if you don't.
+   */
+#define HAVE_DECL_SIGHUP 1
+
+/* Define to 1 if you have the declaration of `SIGINT', and to 0 if you don't.
+   */
+#define HAVE_DECL_SIGINT 1
+
+/* Define to 1 if you have the declaration of `SIGTERM', and to 0 if you
+   don't. */
+#define HAVE_DECL_SIGTERM 1
+
+/* Define to 1 if you have the declaration of `SIGUSR1', and to 0 if you
+   don't. */
+#define HAVE_DECL_SIGUSR1 1
+
+/* Define to 1 if you have the declaration of `SIGUSR2', and to 0 if you
+   don't. */
+#define HAVE_DECL_SIGUSR2 1
+
+/* Define to 1 if you have the declaration of `SO_MARK', and to 0 if you
+   don't. */
+#define HAVE_DECL_SO_MARK 1
+
+/* Define to 1 if you have the declaration of `TUNSETPERSIST', and to 0 if you
+   don't. */
+#define HAVE_DECL_TUNSETPERSIST 1
+
+/* Define to 1 if you have the <direct.h> header file. */
+/* #undef HAVE_DIRECT_H */
+
+/* Define to 1 if you have the `dirname' function. */
+#define HAVE_DIRNAME 1
+
+/* Define to 1 if you have the <dlfcn.h> header file. */
+#define HAVE_DLFCN_H 1
+
+/* Define to 1 if you have the <dmalloc.h> header file. */
+/* #undef HAVE_DMALLOC_H */
+
+/* Define to 1 if you have the `DSA_bits' function. */
+#define HAVE_DSA_BITS 1
+
+/* Define to 1 if you have the `DSA_get0_pqg' function. */
+#define HAVE_DSA_GET0_PQG 1
+
+/* Define to 1 if you have the `dup' function. */
+#define HAVE_DUP 1
+
+/* Define to 1 if you have the `dup2' function. */
+#define HAVE_DUP2 1
+
+/* Define to 1 if you have the `EC_GROUP_order_bits' function. */
+#define HAVE_EC_GROUP_ORDER_BITS 1
+
+/* Define to 1 if you have the `ENGINE_cleanup' function. */
+/* #undef HAVE_ENGINE_CLEANUP */
+
+/* Define to 1 if you have the `ENGINE_load_builtin_engines' function. */
+#define HAVE_ENGINE_LOAD_BUILTIN_ENGINES 1
+
+/* Define to 1 if you have the `ENGINE_register_all_complete' function. */
+#define HAVE_ENGINE_REGISTER_ALL_COMPLETE 1
+
+/* Define to 1 if you have the `epoll_create' function. */
+#define HAVE_EPOLL_CREATE 1
+
+/* Define to 1 if you have the <errno.h> header file. */
+#define HAVE_ERRNO_H 1
+
+/* Define to 1 if you have the <err.h> header file. */
+#define HAVE_ERR_H 1
+
+/* Define to 1 if you have the `EVP_aes_256_gcm' function. */
+#define HAVE_EVP_AES_256_GCM 1
+
+/* Define to 1 if you have the `EVP_CIPHER_CTX_reset' function. */
+#define HAVE_EVP_CIPHER_CTX_RESET 1
+
+/* Define to 1 if you have the `EVP_CIPHER_CTX_set_key_length' function. */
+#define HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH 1
+
+/* Define to 1 if you have the `EVP_MD_CTX_free' function. */
+#define HAVE_EVP_MD_CTX_FREE 1
+
+/* Define to 1 if you have the `EVP_MD_CTX_new' function. */
+#define HAVE_EVP_MD_CTX_NEW 1
+
+/* Define to 1 if you have the `EVP_MD_CTX_reset' function. */
+#define HAVE_EVP_MD_CTX_RESET 1
+
+/* Define to 1 if you have the `EVP_PKEY_get0_DSA' function. */
+#define HAVE_EVP_PKEY_GET0_DSA 1
+
+/* Define to 1 if you have the `EVP_PKEY_get0_EC_KEY' function. */
+#define HAVE_EVP_PKEY_GET0_EC_KEY 1
+
+/* Define to 1 if you have the `EVP_PKEY_get0_RSA' function. */
+#define HAVE_EVP_PKEY_GET0_RSA 1
+
+/* Define to 1 if you have the `EVP_PKEY_id' function. */
+#define HAVE_EVP_PKEY_ID 1
+
+/* Define to 1 if you have the `execve' function. */
+#define HAVE_EXECVE 1
+
+/* Define to 1 if you have the <fcntl.h> header file. */
+#define HAVE_FCNTL_H 1
+
+/* Define to 1 if you have the `flock' function. */
+#define HAVE_FLOCK 1
+
+/* Define to 1 if you have the `fork' function. */
+#define HAVE_FORK 1
+
+/* Define to 1 if you have the `ftruncate' function. */
+#define HAVE_FTRUNCATE 1
+
+/* Define to 1 if you have the `getgrnam' function. */
+#define HAVE_GETGRNAM 1
+
+/* Define to 1 if you have the `gethostbyname' function. */
+#define HAVE_GETHOSTBYNAME 1
+
+/* Define to 1 if you have the `getpass' function. */
+#define HAVE_GETPASS 1
+
+/* Define to 1 if you have the `getpeereid' function. */
+/* #undef HAVE_GETPEEREID */
+
+/* Define to 1 if you have the `getpeername' function. */
+#define HAVE_GETPEERNAME 1
+
+/* Define to 1 if you have the `getpid' function. */
+#define HAVE_GETPID 1
+
+/* Define to 1 if you have the `getpwnam' function. */
+#define HAVE_GETPWNAM 1
+
+/* Define to 1 if you have the `getsockname' function. */
+#define HAVE_GETSOCKNAME 1
+
+/* Define to 1 if you have the `getsockopt' function. */
+#define HAVE_GETSOCKOPT 1
+
+/* Define to 1 if you have the `gettimeofday' function. */
+#define HAVE_GETTIMEOFDAY 1
+
+/* Define to 1 if you have the <grp.h> header file. */
+#define HAVE_GRP_H 1
+
+/* Define to 1 if you have the `HMAC_CTX_free' function. */
+#define HAVE_HMAC_CTX_FREE 1
+
+/* Define to 1 if you have the `HMAC_CTX_new' function. */
+#define HAVE_HMAC_CTX_NEW 1
+
+/* Define to 1 if you have the `HMAC_CTX_reset' function. */
+#define HAVE_HMAC_CTX_RESET 1
+
+/* Define to 1 if you have the `inet_ntoa' function. */
+#define HAVE_INET_NTOA 1
+
+/* Define to 1 if you have the `inet_ntop' function. */
+#define HAVE_INET_NTOP 1
+
+/* Define to 1 if you have the `inet_pton' function. */
+#define HAVE_INET_PTON 1
+
+/* Define to 1 if you have the <inttypes.h> header file. */
+#define HAVE_INTTYPES_H 1
+
+/* Define to 1 if the system has the type `in_addr_t'. */
+#define HAVE_IN_ADDR_T 1
+
+/* struct in_pktinfo needed for IP_PKTINFO support */
+#define HAVE_IN_PKTINFO 1
+
+/* Define to 1 if the system has the type `in_port_t'. */
+#define HAVE_IN_PORT_T 1
+
+/* struct iovec needed for IPv6 support */
+#define HAVE_IOVEC 1
+
+/* Define to 1 if you have the <io.h> header file. */
+/* #undef HAVE_IO_H */
+
+/* struct iphdr needed for IPv6 support */
+#define HAVE_IPHDR 1
+
+/* struct in_pktinfo.ipi_spec_dst needed for IP_PKTINFO support */
+#define HAVE_IPI_SPEC_DST 1
+
+/* Define to 1 if you have the <libgen.h> header file. */
+#define HAVE_LIBGEN_H 1
+
+/* Define to 1 if you have the `lz4' library (-llz4). */
+/* #undef HAVE_LIBLZ4 */
+
+/* Define to 1 if you have the <limits.h> header file. */
+#define HAVE_LIMITS_H 1
+
+/* Define to 1 if you have the <linux/if_tun.h> header file. */
+#define HAVE_LINUX_IF_TUN_H 1
+
+/* Define to 1 if you have the <linux/sockios.h> header file. */
+#define HAVE_LINUX_SOCKIOS_H 1
+
+/* Define to 1 if you have the <linux/types.h> header file. */
+#define HAVE_LINUX_TYPES_H 1
+
+/* Define to 1 if you have the `listen' function. */
+#define HAVE_LISTEN 1
+
+/* Define to 1 if you have the <lz4.h> header file. */
+/* #undef HAVE_LZ4_H */
+
+/* Define to 1 if you have the <lzo1x.h> header file. */
+/* #undef HAVE_LZO1X_H */
+
+/* Define to 1 if you have the <lzoutil.h> header file. */
+/* #undef HAVE_LZOUTIL_H */
+
+/* Define to 1 if you have the <lzo/lzo1x.h> header file. */
+#define HAVE_LZO_LZO1X_H 1
+
+/* Define to 1 if you have the <lzo/lzoutil.h> header file. */
+#define HAVE_LZO_LZOUTIL_H 1
+
+/* Define to 1 if you have the `mbedtls_cipher_check_tag' function. */
+/* #undef HAVE_MBEDTLS_CIPHER_CHECK_TAG */
+
+/* Define to 1 if you have the `mbedtls_cipher_write_tag' function. */
+/* #undef HAVE_MBEDTLS_CIPHER_WRITE_TAG */
+
+/* Define to 1 if you have the <memory.h> header file. */
+#define HAVE_MEMORY_H 1
+
+/* Define to 1 if you have the `memset' function. */
+#define HAVE_MEMSET 1
+
+/* Define to 1 if you have the `mlockall' function. */
+#define HAVE_MLOCKALL 1
+
+/* struct msghdr needed for extended socket error support */
+#define HAVE_MSGHDR 1
+
+/* Define to 1 if you have the <netdb.h> header file. */
+#define HAVE_NETDB_H 1
+
+/* Define to 1 if you have the <netinet/in.h> header file. */
+#define HAVE_NETINET_IN_H 1
+
+/* Define to 1 if you have the <netinet/in_systm.h> header file. */
+#define HAVE_NETINET_IN_SYSTM_H 1
+
+/* Define to 1 if you have the <netinet/ip.h> header file. */
+#define HAVE_NETINET_IP_H 1
+
+/* Define to 1 if you have the <netinet/tcp.h> header file. */
+#define HAVE_NETINET_TCP_H 1
+
+/* Define to 1 if you have the <net/if.h> header file. */
+#define HAVE_NET_IF_H 1
+
+/* Define to 1 if you have the <net/if_tun.h> header file. */
+/* #undef HAVE_NET_IF_TUN_H */
+
+/* Define to 1 if you have the <net/if_utun.h> header file. */
+/* #undef HAVE_NET_IF_UTUN_H */
+
+/* Define to 1 if you have the <net/tun/if_tun.h> header file. */
+/* #undef HAVE_NET_TUN_IF_TUN_H */
+
+/* Define to 1 if you have the `nice' function. */
+#define HAVE_NICE 1
+
+/* Define to 1 if you have the `openlog' function. */
+#define HAVE_OPENLOG 1
+
+/* OpenSSL engine support available */
+/* #undef HAVE_OPENSSL_ENGINE */
+
+/* Define to 1 if you have the `poll' function. */
+#define HAVE_POLL 1
+
+/* Define to 1 if you have the `putenv' function. */
+#define HAVE_PUTENV 1
+
+/* Define to 1 if you have the <pwd.h> header file. */
+#define HAVE_PWD_H 1
+
+/* Define to 1 if you have the `readv' function. */
+#define HAVE_READV 1
+
+/* Define to 1 if you have the `recv' function. */
+#define HAVE_RECV 1
+
+/* Define to 1 if you have the `recvfrom' function. */
+#define HAVE_RECVFROM 1
+
+/* Define to 1 if you have the `recvmsg' function. */
+#define HAVE_RECVMSG 1
+
+/* Define to 1 if you have the <resolv.h> header file. */
+#define HAVE_RESOLV_H 1
+
+/* Define to 1 if you have the `RSA_bits' function. */
+#define HAVE_RSA_BITS 1
+
+/* Define to 1 if you have the `RSA_get0_key' function. */
+#define HAVE_RSA_GET0_KEY 1
+
+/* Define to 1 if you have the `RSA_meth_free' function. */
+#define HAVE_RSA_METH_FREE 1
+
+/* Define to 1 if you have the `RSA_meth_get0_app_data' function. */
+#define HAVE_RSA_METH_GET0_APP_DATA 1
+
+/* Define to 1 if you have the `RSA_meth_new' function. */
+#define HAVE_RSA_METH_NEW 1
+
+/* Define to 1 if you have the `RSA_meth_set0_app_data' function. */
+#define HAVE_RSA_METH_SET0_APP_DATA 1
+
+/* Define to 1 if you have the `RSA_meth_set_finish' function. */
+#define HAVE_RSA_METH_SET_FINISH 1
+
+/* Define to 1 if you have the `RSA_meth_set_init' function. */
+#define HAVE_RSA_METH_SET_INIT 1
+
+/* Define to 1 if you have the `RSA_meth_set_priv_dec' function. */
+#define HAVE_RSA_METH_SET_PRIV_DEC 1
+
+/* Define to 1 if you have the `RSA_meth_set_priv_enc' function. */
+#define HAVE_RSA_METH_SET_PRIV_ENC 1
+
+/* Define to 1 if you have the `RSA_meth_set_pub_dec' function. */
+#define HAVE_RSA_METH_SET_PUB_DEC 1
+
+/* Define to 1 if you have the `RSA_meth_set_pub_enc' function. */
+#define HAVE_RSA_METH_SET_PUB_ENC 1
+
+/* Define to 1 if you have the `RSA_meth_set_sign' function. */
+#define HAVE_RSA_METH_SET_SIGN 1
+
+/* Define to 1 if you have the `RSA_set0_key' function. */
+#define HAVE_RSA_SET0_KEY 1
+
+/* Define to 1 if you have the `RSA_set_flags' function. */
+#define HAVE_RSA_SET_FLAGS 1
+
+/* sa_family_t, needed to hold AF_* info */
+#define HAVE_SA_FAMILY_T 1
+
+/* Define to 1 if you have the `sd_booted' function. */
+/* #undef HAVE_SD_BOOTED */
+
+/* Define to 1 if you have the `select' function. */
+#define HAVE_SELECT 1
+
+/* Define to 1 if you have the `send' function. */
+#define HAVE_SEND 1
+
+/* Define to 1 if you have the `sendmsg' function. */
+#define HAVE_SENDMSG 1
+
+/* Define to 1 if you have the `sendto' function. */
+#define HAVE_SENDTO 1
+
+/* Define to 1 if you have the `setgid' function. */
+#define HAVE_SETGID 1
+
+/* Define to 1 if you have the `setgroups' function. */
+#define HAVE_SETGROUPS 1
+
+/* Define to 1 if you have the `setsid' function. */
+#define HAVE_SETSID 1
+
+/* Define to 1 if you have the `setsockopt' function. */
+#define HAVE_SETSOCKOPT 1
+
+/* Define to 1 if you have the `setuid' function. */
+#define HAVE_SETUID 1
+
+/* Define to 1 if you have the <signal.h> header file. */
+#define HAVE_SIGNAL_H 1
+
+/* Define to 1 if you have the `socket' function. */
+#define HAVE_SOCKET 1
+
+/* struct sock_extended_err needed for extended socket error support */
+/* #undef HAVE_SOCK_EXTENDED_ERR */
+
+/* Define to 1 if you have the `SSL_CTX_get_default_passwd_cb' function. */
+#define HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB 1
+
+/* Define to 1 if you have the `SSL_CTX_get_default_passwd_cb_userdata'
+   function. */
+#define HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB_USERDATA 1
+
+/* Define to 1 if you have the `SSL_CTX_new' function. */
+#define HAVE_SSL_CTX_NEW 1
+
+/* Define to 1 if you have the `SSL_CTX_set_security_level' function. */
+#define HAVE_SSL_CTX_SET_SECURITY_LEVEL 1
+
+/* Define to 1 if you have the `stat' function. */
+#define HAVE_STAT 1
+
+/* Define to 1 if you have the <stdarg.h> header file. */
+#define HAVE_STDARG_H 1
+
+/* Define to 1 if you have the <stdint.h> header file. */
+#define HAVE_STDINT_H 1
+
+/* Define to 1 if you have the <stdio.h> header file. */
+#define HAVE_STDIO_H 1
+
+/* Define to 1 if you have the <stdlib.h> header file. */
+#define HAVE_STDLIB_H 1
+
+/* Define to 1 if you have the `strdup' function. */
+#define HAVE_STRDUP 1
+
+/* Define to 1 if you have the <strings.h> header file. */
+#define HAVE_STRINGS_H 1
+
+/* Define to 1 if you have the <string.h> header file. */
+#define HAVE_STRING_H 1
+
+/* Define to 1 if you have the <stropts.h> header file. */
+/* #undef HAVE_STROPTS_H */
+
+/* Define to 1 if you have the `syslog' function. */
+#define HAVE_SYSLOG 1
+
+/* Define to 1 if you have the <syslog.h> header file. */
+#define HAVE_SYSLOG_H 1
+
+/* Define to 1 if you have the `system' function. */
+#define HAVE_SYSTEM 1
+
+/* Define to 1 if you have the <systemd/sd-daemon.h> header file. */
+/* #undef HAVE_SYSTEMD_SD_DAEMON_H */
+
+/* Define to 1 if you have the <sys/epoll.h> header file. */
+#define HAVE_SYS_EPOLL_H 1
+
+/* Define to 1 if you have the <sys/file.h> header file. */
+#define HAVE_SYS_FILE_H 1
+
+/* Define to 1 if you have the <sys/inotify.h> header file. */
+/* #undef HAVE_SYS_INOTIFY_H */
+
+/* Define to 1 if you have the <sys/ioctl.h> header file. */
+#define HAVE_SYS_IOCTL_H 1
+
+/* Define to 1 if you have the <sys/kern_control.h> header file. */
+/* #undef HAVE_SYS_KERN_CONTROL_H */
+
+/* Define to 1 if you have the <sys/mman.h> header file. */
+#define HAVE_SYS_MMAN_H 1
+
+/* Define to 1 if you have the <sys/poll.h> header file. */
+#define HAVE_SYS_POLL_H 1
+
+/* Define to 1 if you have the <sys/socket.h> header file. */
+#define HAVE_SYS_SOCKET_H 1
+
+/* Define to 1 if you have the <sys/sockio.h> header file. */
+/* #undef HAVE_SYS_SOCKIO_H */
+
+/* Define to 1 if you have the <sys/stat.h> header file. */
+#define HAVE_SYS_STAT_H 1
+
+/* Define to 1 if you have the <sys/time.h> header file. */
+#define HAVE_SYS_TIME_H 1
+
+/* Define to 1 if you have the <sys/types.h> header file. */
+#define HAVE_SYS_TYPES_H 1
+
+/* Define to 1 if you have the <sys/uio.h> header file. */
+#define HAVE_SYS_UIO_H 1
+
+/* Define to 1 if you have the <sys/un.h> header file. */
+#define HAVE_SYS_UN_H 1
+
+/* Define to 1 if you have the <sys/wait.h> header file. */
+#define HAVE_SYS_WAIT_H 1
+
+/* Define to 1 if you have the <tap-windows.h> header file. */
+/* #undef HAVE_TAP_WINDOWS_H */
+
+/* Define to 1 if you have the `time' function. */
+#define HAVE_TIME 1
+
+/* Define to 1 if you have the <time.h> header file. */
+#define HAVE_TIME_H 1
+
+/* Define to 1 if you have the `umask' function. */
+#define HAVE_UMASK 1
+
+/* Define to 1 if you have the <unistd.h> header file. */
+#define HAVE_UNISTD_H 1
+
+/* Define to 1 if you have the `unlink' function. */
+#define HAVE_UNLINK 1
+
+/* Define to 1 if you have the <valgrind/memcheck.h> header file. */
+/* #undef HAVE_VALGRIND_MEMCHECK_H */
+
+/* Define to 1 if you have the <versionhelpers.h> header file. */
+/* #undef HAVE_VERSIONHELPERS_H */
+
+/* Define to 1 if you have the `vfork' function. */
+#define HAVE_VFORK 1
+
+/* Define to 1 if you have the <vfork.h> header file. */
+/* #undef HAVE_VFORK_H */
+
+/* Define to 1 if you have the `vsnprintf' function. */
+#define HAVE_VSNPRINTF 1
+
+/* Define to 1 if you have the <windows.h> header file. */
+/* #undef HAVE_WINDOWS_H */
+
+/* Define to 1 if you have the <winsock2.h> header file. */
+/* #undef HAVE_WINSOCK2_H */
+
+/* Define to 1 if `fork' works. */
+#define HAVE_WORKING_FORK 1
+
+/* Define to 1 if `vfork' works. */
+#define HAVE_WORKING_VFORK 1
+
+/* Define to 1 if you have the `writev' function. */
+#define HAVE_WRITEV 1
+
+/* Define to 1 if you have the <ws2tcpip.h> header file. */
+/* #undef HAVE_WS2TCPIP_H */
+
+/* Define to 1 if you have the `X509_get0_notAfter' function. */
+#define HAVE_X509_GET0_NOTAFTER 1
+
+/* Define to 1 if you have the `X509_get0_notBefore' function. */
+#define HAVE_X509_GET0_NOTBEFORE 1
+
+/* Define to 1 if you have the `X509_get0_pubkey' function. */
+#define HAVE_X509_GET0_PUBKEY 1
+
+/* Define to 1 if you have the `X509_OBJECT_free' function. */
+#define HAVE_X509_OBJECT_FREE 1
+
+/* Define to 1 if you have the `X509_OBJECT_get_type' function. */
+#define HAVE_X509_OBJECT_GET_TYPE 1
+
+/* Define to 1 if you have the `X509_STORE_get0_objects' function. */
+#define HAVE_X509_STORE_GET0_OBJECTS 1
+
+/* Path to ifconfig tool */
+#define IFCONFIG_PATH "/sbin/ifconfig"
+
+/* Path to iproute tool */
+#define IPROUTE_PATH "/sbin/ip"
+
+/* Define to the sub-directory where libtool stores uninstalled libraries. */
+#define LT_OBJDIR ".libs/"
+
+/* use copy of LZ4 source in compat/ */
+/* #undef NEED_COMPAT_LZ4 */
+
+/* OpenVPN major version - integer */
+#define OPENVPN_VERSION_MAJOR 2
+
+/* OpenVPN minor version - integer */
+#define OPENVPN_VERSION_MINOR 4
+
+/* OpenVPN patch level - may be a string or integer */
+#define OPENVPN_VERSION_PATCH ".9"
+
+/* Version in windows resource format */
+#define OPENVPN_VERSION_RESOURCE 2,4,9,0
+
+/* Name of package */
+#define PACKAGE "openvpn"
+
+/* Define to the address where bug reports for this package should be sent. */
+#define PACKAGE_BUGREPORT "openvpn-users@lists.sourceforge.net"
+
+/* Define to the full name of this package. */
+#define PACKAGE_NAME "OpenVPN"
+
+/* Define to the full name and version of this package. */
+#define PACKAGE_STRING "OpenVPN 2.4.9"
+
+/* Define to the one symbol short name of this package. */
+#define PACKAGE_TARNAME "openvpn"
+
+/* Define to the home page for this package. */
+#define PACKAGE_URL ""
+
+/* Define to the version of this package. */
+#define PACKAGE_VERSION "2.4.9"
+
+/* Path separator */
+#define PATH_SEPARATOR '/'
+
+/* Path separator */
+#define PATH_SEPARATOR_STR "/"
+
+/* Enable pedantic mode */
+/* #undef PEDANTIC */
+
+/* Define as the return type of signal handlers (`int' or `void'). */
+#define RETSIGTYPE void
+
+/* Path to route tool */
+#define ROUTE_PATH "/sbin/route"
+
+/* SIGHUP replacement */
+/* #undef SIGHUP */
+
+/* SIGINT replacement */
+/* #undef SIGINT */
+
+/* SIGTERM replacement */
+/* #undef SIGTERM */
+
+/* SIGUSR1 replacement */
+/* #undef SIGUSR1 */
+
+/* SIGUSR2 replacement */
+/* #undef SIGUSR2 */
+
+/* The size of `unsigned int', as computed by sizeof. */
+#define SIZEOF_UNSIGNED_INT 4
+
+/* The size of `unsigned long', as computed by sizeof. */
+#define SIZEOF_UNSIGNED_LONG 8
+
+/* Define to 1 if you have the ANSI C header files. */
+#define STDC_HEADERS 1
+
+/* Path to systemd-ask-password tool */
+#define SYSTEMD_ASK_PASSWORD_PATH "/bin/systemd-ask-password"
+
+/* systemd is newer than v216 */
+/* #undef SYSTEMD_NEWER_THAN_216 */
+
+/* The tap-windows id */
+#define TAP_WIN_COMPONENT_ID "tap0901"
+
+/* The tap-windows version number is required for OpenVPN */
+#define TAP_WIN_MIN_MAJOR 9
+
+/* The tap-windows version number is required for OpenVPN */
+#define TAP_WIN_MIN_MINOR 9
+
+/* Are we running AIX? */
+/* #undef TARGET_AIX */
+
+/* A string representing our host */
+#define TARGET_ALIAS "x86_64-pc-linux-gnu"
+
+/* Are we running on Mac OS X? */
+/* #undef TARGET_DARWIN */
+
+/* Are we running on DragonFlyBSD? */
+/* #undef TARGET_DRAGONFLY */
+
+/* Are we running on FreeBSD? */
+/* #undef TARGET_FREEBSD */
+
+/* Are we running on Linux? */
+#define TARGET_LINUX 1
+
+/* Are we running NetBSD? */
+/* #undef TARGET_NETBSD */
+
+/* Are we running on OpenBSD? */
+/* #undef TARGET_OPENBSD */
+
+/* Target prefix */
+#define TARGET_PREFIX "L"
+
+/* Are we running on Solaris? */
+/* #undef TARGET_SOLARIS */
+
+/* Are we running WIN32? */
+/* #undef TARGET_WIN32 */
+
+/* dlopen libpam */
+/* #undef USE_PAM_DLOPEN */
+
+/* Enable extensions on AIX 3, Interix.  */
+#ifndef _ALL_SOURCE
+# define _ALL_SOURCE 1
+#endif
+/* Enable GNU extensions on systems that have them.  */
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE 1
+#endif
+/* Enable threading extensions on Solaris.  */
+#ifndef _POSIX_PTHREAD_SEMANTICS
+# define _POSIX_PTHREAD_SEMANTICS 1
+#endif
+/* Enable extensions on HP NonStop.  */
+#ifndef _TANDEM_SOURCE
+# define _TANDEM_SOURCE 1
+#endif
+/* Enable general extensions on Solaris.  */
+#ifndef __EXTENSIONS__
+# define __EXTENSIONS__ 1
+#endif
+
+
+/* Use valgrind memory debugging library */
+/* #undef USE_VALGRIND */
+
+/* Version number of package */
+#define VERSION "2.4.9"
+
+/* Define to 1 if on MINIX. */
+/* #undef _MINIX */
+
+/* Define to 2 if the system does not provide POSIX.1 features except with
+   this defined. */
+/* #undef _POSIX_1_SOURCE */
+
+/* Define to 1 if you need to in order for `stat' and other things to work. */
+/* #undef _POSIX_SOURCE */
+
+/* Define for Solaris 2.5.1 so the uint32_t typedef from <sys/synch.h>,
+   <pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the
+   #define below would cause a syntax error. */
+/* #undef _UINT32_T */
+
+/* Define for Solaris 2.5.1 so the uint64_t typedef from <sys/synch.h>,
+   <pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the
+   #define below would cause a syntax error. */
+/* #undef _UINT64_T */
+
+/* Define for Solaris 2.5.1 so the uint8_t typedef from <sys/synch.h>,
+   <pthread.h>, or <semaphore.h> is not used. If the typedef were allowed, the
+   #define below would cause a syntax error. */
+/* #undef _UINT8_T */
+
+/* Define to empty if `const' does not conform to ANSI C. */
+/* #undef const */
+
+/* Define to `int' if <sys/types.h> doesn't define. */
+/* #undef gid_t */
+
+/* Workaround missing in_addr_t */
+/* #undef in_addr_t */
+
+/* Workaround missing in_port_t */
+/* #undef in_port_t */
+
+/* Define to `__inline__' or `__inline' if that's what the C compiler
+   calls it, or to nothing if 'inline' is not supported under any name.  */
+#ifndef __cplusplus
+/* #undef inline */
+#endif
+
+/* Define to the type of a signed integer type of width exactly 16 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef int16_t */
+
+/* Define to the type of a signed integer type of width exactly 32 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef int32_t */
+
+/* Define to the type of a signed integer type of width exactly 64 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef int64_t */
+
+/* Define to the type of a signed integer type of width exactly 8 bits if such
+   a type exists and the standard includes do not define it. */
+/* #undef int8_t */
+
+/* Define to `long int' if <sys/types.h> does not define. */
+/* #undef off_t */
+
+/* Define to `int' if <sys/types.h> does not define. */
+/* #undef pid_t */
+
+/* Define to `unsigned int' if <sys/types.h> does not define. */
+/* #undef size_t */
+
+/* type to use in place of socklen_t if not defined */
+/* #undef socklen_t */
+
+/* Define to `int' if <sys/types.h> doesn't define. */
+/* #undef uid_t */
+
+/* Define to the type of an unsigned integer type of width exactly 16 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef uint16_t */
+
+/* Define to the type of an unsigned integer type of width exactly 32 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef uint32_t */
+
+/* Define to the type of an unsigned integer type of width exactly 64 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef uint64_t */
+
+/* Define to the type of an unsigned integer type of width exactly 8 bits if
+   such a type exists and the standard includes do not define it. */
+/* #undef uint8_t */
+
+/* Define as `fork' if `vfork' does not work. */
+/* #undef vfork */
+
+/* Define to empty if the keyword `volatile' does not work. Warning: valid
+   code using `volatile' can become incorrect without. Disable with care. */
+/* #undef volatile */
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 0000000..f61255b
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,1424 @@
+dnl  OpenVPN -- An application to securely tunnel IP networks
+dnl             over a single UDP port, with support for SSL/TLS-based
+dnl             session authentication and key exchange,
+dnl             packet encryption, packet authentication, and
+dnl             packet compression.
+dnl
+dnl  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+dnl  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+dnl
+dnl  This program is free software; you can redistribute it and/or modify
+dnl  it under the terms of the GNU General Public License as published by
+dnl  the Free Software Foundation; either version 2 of the License, or
+dnl  (at your option) any later version.
+dnl
+dnl  This program is distributed in the hope that it will be useful,
+dnl  but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl  GNU General Public License for more details.
+dnl
+dnl  You should have received a copy of the GNU General Public License along
+dnl  with this program; if not, write to the Free Software Foundation, Inc.,
+dnl  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+dnl Process this file with autoconf to produce a configure script.
+
+AC_PREREQ(2.59)
+
+m4_include(version.m4)
+AC_INIT([PRODUCT_NAME], [PRODUCT_VERSION], [PRODUCT_BUGREPORT], [PRODUCT_TARNAME])
+m4_include(compat.m4)
+AC_DEFINE([OPENVPN_VERSION_RESOURCE], [PRODUCT_VERSION_RESOURCE], [Version in windows resource format])
+AC_SUBST([OPENVPN_VERSION_MAJOR], [PRODUCT_VERSION_MAJOR], [OpenVPN major version])
+AC_SUBST([OPENVPN_VERSION_MINOR], [PRODUCT_VERSION_MINOR], [OpenVPN minor version])
+AC_SUBST([OPENVPN_VERSION_PATCH], [PRODUCT_VERSION_PATCH], [OpenVPN patch level - may be a string or integer])
+AC_DEFINE([OPENVPN_VERSION_MAJOR], [PRODUCT_VERSION_MAJOR], [OpenVPN major version - integer])
+AC_DEFINE([OPENVPN_VERSION_MINOR], [PRODUCT_VERSION_MINOR], [OpenVPN minor version - integer])
+AC_DEFINE([OPENVPN_VERSION_PATCH], ["PRODUCT_VERSION_PATCH"], [OpenVPN patch level - may be a string or integer])
+
+AC_CONFIG_AUX_DIR([.])
+AC_CONFIG_HEADERS([config.h include/openvpn-plugin.h])
+AC_CONFIG_SRCDIR([src/openvpn/syshead.h])
+AC_CONFIG_MACRO_DIR([m4])
+
+dnl Initialize automake.  automake < 1.12 didn't have serial-tests and
+dnl gives an error if it sees this, but for automake >= 1.13
+dnl serial-tests is required so we have to include it.  Solution is to
+dnl test for the version of automake (by running an external command)
+dnl and provide it if necessary.  Note we have to do this entirely using
+dnl m4 macros since automake queries this macro by running
+dnl 'autoconf --trace ...'.
+m4_define([serial_tests], [
+    m4_esyscmd([automake --version |
+                head -1 |
+                awk '{split ($NF,a,"."); if (a[1] == 1 && a[2] >= 12) { print "serial-tests" }}'
+    ])
+])
+AM_INIT_AUTOMAKE(foreign serial_tests) dnl NB: Do not [quote] this parameter.
+AC_CANONICAL_HOST
+AC_USE_SYSTEM_EXTENSIONS
+
+AC_ARG_ENABLE(
+	[lzo],
+	[AS_HELP_STRING([--disable-lzo], [disable LZO compression support @<:@default=yes@:>@])],
+	,
+	[enable_lzo="yes"]
+)
+
+AC_ARG_ENABLE(lz4,
+	[  --disable-lz4           Disable LZ4 compression support],
+	[enable_lz4="$enableval"],
+	[enable_lz4="yes"]
+)
+
+AC_ARG_ENABLE(comp-stub,
+	[  --enable-comp-stub      Don't compile compression support but still allow limited interoperability with compression-enabled peers],
+	[enable_comp_stub="$enableval"],
+	[enable_comp_stub="no"]
+)
+
+AC_ARG_ENABLE(
+	[crypto],
+	[AS_HELP_STRING([--disable-crypto], [disable crypto support @<:@default=yes@:>@])],
+	,
+	[enable_crypto="yes"]
+)
+
+AC_ARG_ENABLE(
+	[ofb-cfb],
+	[AS_HELP_STRING([--disable-ofb-cfb], [disable support for OFB and CFB cipher modes @<:@default=yes@:>@])],
+	,
+	[enable_crypto_ofb_cfb="yes"]
+)
+
+AC_ARG_ENABLE(
+	[x509-alt-username],
+	[AS_HELP_STRING([--enable-x509-alt-username], [enable the --x509-username-field feature @<:@default=no@:>@])],
+	,
+	[enable_x509_alt_username="no"]
+)
+
+AC_ARG_ENABLE(
+	[server],
+	[AS_HELP_STRING([--disable-server], [disable server support only (but retain client support) @<:@default=yes@:>@])],
+	,
+	[enable_server="yes"]
+)
+
+AC_ARG_ENABLE(
+	[plugins],
+	[AS_HELP_STRING([--disable-plugins], [disable plug-in support @<:@default=yes@:>@])],
+	,
+	[enable_plugins="yes"]
+)
+
+AC_ARG_ENABLE(
+	[management],
+	[AS_HELP_STRING([--disable-management], [disable management server support @<:@default=yes@:>@])],
+	,
+	[enable_management="yes"]
+)
+
+AC_ARG_ENABLE(
+	[pkcs11],
+	[AS_HELP_STRING([--enable-pkcs11], [enable pkcs11 support @<:@default=no@:>@])],
+	,
+	[enable_pkcs11="no"]
+)
+
+AC_ARG_ENABLE(
+	[fragment],
+	[AS_HELP_STRING([--disable-fragment], [disable internal fragmentation support (--fragment) @<:@default=yes@:>@])],
+	,
+	[enable_fragment="yes"]
+)
+
+AC_ARG_ENABLE(
+	[multihome],
+	[AS_HELP_STRING([--disable-multihome], [disable multi-homed UDP server support (--multihome) @<:@default=yes@:>@])],
+	,
+	[enable_multihome="yes"]
+)
+
+AC_ARG_ENABLE(
+	[port-share],
+	[AS_HELP_STRING([--disable-port-share], [disable TCP server port-share support (--port-share) @<:@default=yes@:>@])],
+	,
+	[enable_port_share="yes"]
+)
+
+AC_ARG_ENABLE(
+	[debug],
+	[AS_HELP_STRING([--disable-debug], [disable debugging support (disable gremlin and verb 7+ messages) @<:@default=yes@:>@])],
+	,
+	[enable_debug="yes"]
+)
+
+AC_ARG_ENABLE(
+	[small],
+	[AS_HELP_STRING([--enable-small], [enable smaller executable size (disable OCC, usage message, and verb 4 parm list) @<:@default=no@:>@])],
+	,
+	[enable_small="no"]
+)
+
+AC_ARG_ENABLE(
+	[iproute2],
+	[AS_HELP_STRING([--enable-iproute2], [enable support for iproute2 @<:@default=no@:>@])],
+	,
+	[enable_iproute2="no"]
+)
+
+AC_ARG_ENABLE(
+	[def-auth],
+	[AS_HELP_STRING([--disable-def-auth], [disable deferred authentication @<:@default=yes@:>@])],
+	,
+	[enable_def_auth="yes"]
+)
+
+AC_ARG_ENABLE(
+	[pf],
+	[AS_HELP_STRING([--disable-pf], [disable internal packet filter @<:@default=yes@:>@])],
+	,
+	[enable_pf="yes"]
+)
+
+AC_ARG_ENABLE(
+	[plugin-auth-pam],
+	[AS_HELP_STRING([--disable-plugin-auth-pam], [disable auth-pam plugin @<:@default=platform specific@:>@])],
+	,
+	[
+		case "$host" in
+			*-*-openbsd*) enable_plugin_auth_pam="no";;
+			*-mingw*) enable_plugin_auth_pam="no";;
+			*) enable_plugin_auth_pam="yes";;
+		esac
+	]
+)
+
+AC_ARG_ENABLE(
+	[plugin-down-root],
+	[AS_HELP_STRING([--disable-plugin-down-root], [disable down-root plugin @<:@default=platform specific@:>@])],
+	,
+	[
+		case "$host" in
+			*-mingw*) enable_plugin_down_root="no";;
+			*) enable_plugin_down_root="yes";;
+		esac
+	]
+)
+
+AC_ARG_ENABLE(
+	[pam-dlopen],
+	[AS_HELP_STRING([--enable-pam-dlopen], [dlopen libpam @<:@default=no@:>@])],
+	,
+	[enable_pam_dlopen="no"]
+)
+
+AC_ARG_ENABLE(
+	[strict],
+	[AS_HELP_STRING([--enable-strict], [enable strict compiler warnings (debugging option) @<:@default=no@:>@])],
+	,
+	[enable_strict="no"]
+)
+
+AC_ARG_ENABLE(
+	[pedantic],
+	[AS_HELP_STRING([--enable-pedantic], [enable pedantic compiler warnings, will not generate a working executable (debugging option) @<:@default=no@:>@])],
+	,
+	[enable_pedantic="no"]
+)
+
+AC_ARG_ENABLE(
+	[werror],
+	[AS_HELP_STRING([--enable-werror], [promote compiler warnings to errors, will cause builds to fail if the compiler issues warnings (debugging option) @<:@default=no@:>@])],
+	,
+	[enable_werror="no"]
+)
+
+AC_ARG_ENABLE(
+	[strict-options],
+	[AS_HELP_STRING([--enable-strict-options], [enable strict options check between peers (debugging option) @<:@default=no@:>@])],
+	,
+	[enable_strict_options="no"]
+)
+
+AC_ARG_ENABLE(
+	[selinux],
+	[AS_HELP_STRING([--enable-selinux], [enable SELinux support @<:@default=no@:>@])],
+	,
+	[enable_selinux="no"]
+)
+
+AC_ARG_ENABLE(
+	[systemd],
+	[AS_HELP_STRING([--enable-systemd], [enable systemd suppport @<:@default=no@:>@])],
+	,
+	[enable_systemd="no"]
+)
+
+AC_ARG_ENABLE(
+	[async-push],
+	[AS_HELP_STRING([--enable-async-push], [enable async-push support for plugins providing deferred authentication @<:@default=no@:>@])],
+	,
+	[enable_async_push="no"]
+)
+
+AC_ARG_WITH(
+	[special-build],
+	[AS_HELP_STRING([--with-special-build=STRING], [specify special build string])],
+	[test -n "${withval}" && AC_DEFINE_UNQUOTED([CONFIGURE_SPECIAL_BUILD], ["${withval}"], [special build string])]
+)
+
+AC_ARG_WITH(
+	[mem-check],
+	[AS_HELP_STRING([--with-mem-check=TYPE], [build with debug memory checking, TYPE=no|dmalloc|valgrind|ssl @<:@default=no@:>@])],
+	[
+		case "${withval}" in
+			dmalloc|valgrind|ssl|no) ;;
+			*) AC_MSG_ERROR([bad value ${withval} for --mem-check]) ;;
+		esac
+	],
+	[with_mem_check="no"]
+)
+
+AC_ARG_WITH(
+	[crypto-library],
+	[AS_HELP_STRING([--with-crypto-library=library], [build with the given crypto library, TYPE=openssl|mbedtls @<:@default=openssl@:>@])],
+	[
+		case "${withval}" in
+			openssl|mbedtls) ;;
+			*) AC_MSG_ERROR([bad value ${withval} for --with-crypto-library]) ;;
+		esac
+	],
+	[with_crypto_library="openssl"]
+)
+
+AC_ARG_VAR([PLUGINDIR], [Path of plug-in directory @<:@default=LIBDIR/openvpn/plugins@:>@])
+if test -n "${PLUGINDIR}"; then
+	plugindir="${PLUGINDIR}"
+else
+	plugindir="\${libdir}/openvpn/plugins"
+fi
+
+AC_DEFINE_UNQUOTED([TARGET_ALIAS], ["${host}"], [A string representing our host])
+case "$host" in
+	*-*-linux*)
+		AC_DEFINE([TARGET_LINUX], [1], [Are we running on Linux?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["L"], [Target prefix])
+		;;
+	*-*-solaris*)
+		AC_DEFINE([TARGET_SOLARIS], [1], [Are we running on Solaris?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["S"], [Target prefix])
+		CPPFLAGS="$CPPFLAGS -D_XPG4_2"
+		;;
+	*-*-openbsd*)
+		AC_DEFINE([TARGET_OPENBSD], [1], [Are we running on OpenBSD?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["O"], [Target prefix])
+		;;
+	*-*-freebsd*)
+		AC_DEFINE([TARGET_FREEBSD], [1], [Are we running on FreeBSD?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["F"], [Target prefix])
+		;;
+	*-*-netbsd*)
+		AC_DEFINE([TARGET_NETBSD], [1], [Are we running NetBSD?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["N"], [Target prefix])
+		;;
+	*-*-darwin*)
+		AC_DEFINE([TARGET_DARWIN], [1], [Are we running on Mac OS X?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["M"], [Target prefix])
+		have_tap_header="yes"
+		ac_cv_type_struct_in_pktinfo=no
+		;;
+	*-mingw*)
+		AC_DEFINE([TARGET_WIN32], [1], [Are we running WIN32?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["W"], [Target prefix])
+		CPPFLAGS="${CPPFLAGS} -DWIN32_LEAN_AND_MEAN"
+		CPPFLAGS="${CPPFLAGS} -DNTDDI_VERSION=NTDDI_VISTA -D_WIN32_WINNT=_WIN32_WINNT_VISTA"
+		WIN32=yes
+		;;
+	*-*-dragonfly*)
+		AC_DEFINE([TARGET_DRAGONFLY], [1], [Are we running on DragonFlyBSD?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["D"], [Target prefix])
+		;;
+	*-aix*)
+		AC_DEFINE([TARGET_AIX], [1], [Are we running AIX?])
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["A"], [Target prefix])
+		ROUTE="/usr/sbin/route"
+		have_tap_header="yes"
+		ac_cv_header_net_if_h="no"	# exists, but breaks things
+		;;
+	*)
+		AC_DEFINE_UNQUOTED([TARGET_PREFIX], ["X"], [Target prefix])
+		have_tap_header="yes"
+		;;
+esac
+
+PKG_PROG_PKG_CONFIG
+AC_PROG_CPP
+AC_PROG_INSTALL
+AC_PROG_LN_S
+AC_PROG_SED
+AC_PROG_MAKE_SET
+
+AC_ARG_VAR([IFCONFIG], [full path to ipconfig utility])
+AC_ARG_VAR([ROUTE], [full path to route utility])
+AC_ARG_VAR([IPROUTE], [full path to ip utility])
+AC_ARG_VAR([NETSTAT], [path to netstat utility]) # tests
+AC_ARG_VAR([MAN2HTML], [path to man2html utility])
+AC_ARG_VAR([GIT], [path to git utility])
+AC_ARG_VAR([SYSTEMD_ASK_PASSWORD], [path to systemd-ask-password utility])
+AC_ARG_VAR([SYSTEMD_UNIT_DIR], [Path of systemd unit directory @<:@default=LIBDIR/systemd/system@:>@])
+AC_ARG_VAR([TMPFILES_DIR], [Path of tmpfiles directory @<:@default=LIBDIR/tmpfiles.d@:>@])
+AC_PATH_PROGS([IFCONFIG], [ifconfig],, [$PATH:/usr/local/sbin:/usr/sbin:/sbin])
+AC_PATH_PROGS([ROUTE], [route],, [$PATH:/usr/local/sbin:/usr/sbin:/sbin])
+AC_PATH_PROGS([IPROUTE], [ip],, [$PATH:/usr/local/sbin:/usr/sbin:/sbin])
+AC_PATH_PROGS([SYSTEMD_ASK_PASSWORD], [systemd-ask-password],, [$PATH:/usr/local/bin:/usr/bin:/bin])
+AC_CHECK_PROGS([NETSTAT], [netstat], [netstat], [$PATH:/usr/local/sbin:/usr/sbin:/sbin:/etc]) # tests
+AC_CHECK_PROGS([MAN2HTML], [man2html])
+AC_CHECK_PROGS([GIT], [git]) # optional
+AC_DEFINE_UNQUOTED([IFCONFIG_PATH], ["$IFCONFIG"], [Path to ifconfig tool])
+AC_DEFINE_UNQUOTED([IPROUTE_PATH], ["$IPROUTE"], [Path to iproute tool])
+AC_DEFINE_UNQUOTED([ROUTE_PATH], ["$ROUTE"], [Path to route tool])
+AC_DEFINE_UNQUOTED([SYSTEMD_ASK_PASSWORD_PATH], ["$SYSTEMD_ASK_PASSWORD"], [Path to systemd-ask-password tool])
+
+# Set -std=c99 unless user already specified a -std=
+case "${CFLAGS}" in
+  *-std=*) ;;
+  *)       CFLAGS="${CFLAGS} -std=c99" ;;
+esac
+
+#
+# Libtool
+#
+ifdef(
+	[LT_INIT],
+	[
+		LT_INIT([win32-dll])
+		LT_LANG([Windows Resource])
+	],
+	[
+		AC_LIBTOOL_WIN32_DLL
+		AC_LIBTOOL_RC
+		AC_PROG_LIBTOOL
+	]
+)
+
+AC_C_CONST
+AC_C_INLINE
+AC_C_VOLATILE
+AC_TYPE_OFF_T
+AC_TYPE_PID_T
+AC_TYPE_SIZE_T
+AC_TYPE_UID_T
+AC_TYPE_INT8_T
+AC_TYPE_INT16_T
+AC_TYPE_INT32_T
+AC_TYPE_INT64_T
+AC_TYPE_UINT8_T
+AC_TYPE_UINT16_T
+AC_TYPE_UINT32_T
+AC_TYPE_UINT64_T
+AC_TYPE_SIGNAL
+AX_CPP_VARARG_MACRO_ISO
+AX_CPP_VARARG_MACRO_GCC
+AX_TYPE_SOCKLEN_T
+AX_EMPTY_ARRAY
+AC_CHECK_SIZEOF([unsigned int])
+AC_CHECK_SIZEOF([unsigned long])
+AC_CHECK_HEADERS([ \
+	stdio.h stdarg.h limits.h \
+	time.h errno.h fcntl.h io.h direct.h \
+	ctype.h sys/types.h sys/socket.h \
+	signal.h unistd.h dlfcn.h \
+	netinet/in.h netinet/in_systm.h \
+	netinet/tcp.h arpa/inet.h netdb.h \
+	windows.h winsock2.h ws2tcpip.h \
+	versionhelpers.h \
+])
+AC_CHECK_HEADERS([ \
+	sys/time.h sys/ioctl.h sys/stat.h \
+	sys/mman.h sys/file.h sys/wait.h \
+	unistd.h signal.h libgen.h stropts.h \
+	syslog.h pwd.h grp.h \
+	sys/sockio.h sys/uio.h linux/sockios.h \
+	linux/types.h sys/poll.h sys/epoll.h err.h \
+])
+
+SOCKET_INCLUDES="
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+#ifdef HAVE_WINDOWS_H
+#include <windows.h>
+#endif
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#endif
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+#ifdef HAVE_NETINET_IN_SYSTM_H
+#include <netinet/in_systm.h>
+#endif
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+"
+
+AC_CHECK_HEADERS(
+	[net/if.h netinet/ip.h resolv.h sys/un.h net/if_utun.h sys/kern_control.h],
+	,
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+
+AC_CHECK_TYPES(
+	[in_addr_t],
+	,
+	[AC_DEFINE([in_addr_t], [uint32_t], [Workaround missing in_addr_t])],
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPES(
+	[in_port_t],
+	,
+	[AC_DEFINE([in_port_t], [uint16_t], [Workaround missing in_port_t])],
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct iphdr],
+	[AC_DEFINE([HAVE_IPHDR], [1], [struct iphdr needed for IPv6 support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct sock_extended_err],
+	[AC_DEFINE([HAVE_SOCK_EXTENDED_ERR], [1], [struct sock_extended_err needed for extended socket error support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct msghdr],
+	[AC_DEFINE([HAVE_MSGHDR], [1], [struct msghdr needed for extended socket error support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct cmsghdr],
+	[AC_DEFINE([HAVE_CMSGHDR], [1], [struct cmsghdr needed for extended socket error support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct in_pktinfo],
+	[AC_DEFINE([HAVE_IN_PKTINFO], [1], [struct in_pktinfo needed for IP_PKTINFO support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+        [sa_family_t],
+        [AC_DEFINE([HAVE_SA_FAMILY_T], [1], [sa_family_t, needed to hold AF_* info])],
+        ,
+        [[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_MEMBER(
+	[struct in_pktinfo.ipi_spec_dst],
+	[AC_DEFINE([HAVE_IPI_SPEC_DST], [1], [struct in_pktinfo.ipi_spec_dst needed for IP_PKTINFO support])],
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_TYPE(
+	[struct sockaddr_in6],
+	,
+	[AC_MSG_ERROR([struct sockaddr_in6 not found, needed for ipv6 transport support.])],
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECK_DECLS(
+	[SO_MARK],
+	,
+	,
+	[[${SOCKET_INCLUDES}]]
+)
+AC_CHECKING([anonymous union support])
+AC_COMPILE_IFELSE(
+	[AC_LANG_PROGRAM(
+		[[
+			struct mystruct {
+			  union {
+			    int m1;
+			    char m2;
+			  };
+			};
+		]],
+		[[
+			struct mystruct s;
+			s.m1 = 1; s.m2 = 2;
+		]]
+	)],
+	[
+		AC_MSG_RESULT([yes])
+		AC_DEFINE([HAVE_ANONYMOUS_UNION_SUPPORT], [], [Compiler supports anonymous unions])
+	],
+	[AC_MSG_RESULT([no])]
+)
+
+saved_LDFLAGS="$LDFLAGS"
+LDFLAGS="$LDFLAGS -Wl,--wrap=exit"
+AC_MSG_CHECKING([linker supports --wrap])
+AC_LINK_IFELSE(
+	[AC_LANG_PROGRAM(
+		[[
+			void exit(int);
+			void __real_exit(int);
+			void __wrap_exit(int i) {
+				__real_exit(i);
+			}
+		]],
+		[[
+			exit(0);
+		]]
+	)],
+	[
+		AC_MSG_RESULT([yes])
+		have_ld_wrap_support=yes
+	],
+	[AC_MSG_RESULT([no])],
+)
+LDFLAGS="$saved_LDFLAGS"
+
+dnl We emulate signals in Windows
+AC_CHECK_DECLS(
+	[SIGHUP],
+	,
+	[AC_DEFINE([SIGHUP], [1], [SIGHUP replacement])],
+	[[
+		#ifdef HAVE_SIGNAL_H
+		#include <signal.h>
+		#endif
+	]]
+)
+AC_CHECK_DECLS(
+	[SIGINT],
+	,
+	[AC_DEFINE([SIGINT], [2], [SIGINT replacement])],
+	[[
+		#ifdef HAVE_SIGNAL_H
+		#include <signal.h>
+		#endif
+	]]
+)
+AC_CHECK_DECLS(
+	[SIGUSR1],
+	,
+	[AC_DEFINE([SIGUSR1], [10], [SIGUSR1 replacement])],
+	[[
+		#ifdef HAVE_SIGNAL_H
+		#include <signal.h>
+		#endif
+	]]
+)
+AC_CHECK_DECLS(
+	[SIGUSR2],
+	,
+	[AC_DEFINE([SIGUSR2], [12], [SIGUSR2 replacement])],
+	[[
+		#ifdef HAVE_SIGNAL_H
+		#include <signal.h>
+		#endif
+	]]
+)
+AC_CHECK_DECLS(
+	[SIGTERM],
+	,
+	[AC_DEFINE([SIGTERM], [15], [SIGTERM replacement])],
+	[[
+		#ifdef HAVE_SIGNAL_H
+		#include <signal.h>
+		#endif
+	]]
+)
+
+AC_FUNC_FORK
+
+AC_CHECK_FUNCS([ \
+	daemon chroot getpwnam setuid nice system getpid dup dup2 \
+	getpass syslog openlog mlockall getgrnam setgid \
+	setgroups stat flock readv writev time gettimeofday \
+	ctime memset vsnprintf strdup \
+	setsid chdir putenv getpeername unlink \
+	chsize ftruncate execve getpeereid umask basename dirname access \
+	epoll_create \
+])
+
+AC_CHECK_LIB(
+	[dl],
+	[dlopen],
+	[DL_LIBS="-ldl"]
+)
+AC_SUBST([DL_LIBS])
+
+AC_CHECK_LIB(
+	[nsl],
+	[inet_ntoa],
+	[SOCKETS_LIBS="${SOCKETS_LIBS} -lnsl"]
+)
+AC_CHECK_LIB(
+	[socket],
+	[socket],
+	[SOCKETS_LIBS="${SOCKETS_LIBS} -lsocket"]
+)
+AC_CHECK_LIB(
+	[resolv],
+	[gethostbyname],
+	[SOCKETS_LIBS="${SOCKETS_LIBS} -lresolv"]
+)
+AC_SUBST([SOCKETS_LIBS])
+
+old_LIBS="${LIBS}"
+LIBS="${LIBS} ${SOCKETS_LIBS}"
+AC_CHECK_FUNCS([sendmsg recvmsg])
+# Windows use stdcall for winsock so we cannot auto detect these
+m4_define(
+	[SOCKET_FUNCS],
+[socket recv recvfrom send sendto listen dnl
+accept connect bind select gethostbyname inet_ntoa]dnl
+)
+m4_define(
+	[SOCKET_OPT_FUNCS],
+	[setsockopt getsockopt getsockname poll]dnl
+)
+if test "${WIN32}" = "yes"; then
+# normal autoconf function checking does not find inet_ntop/inet_pton
+# because they need to include the actual header file and link ws2_32.dll
+	LIBS="${LIBS} -lws2_32"
+	AC_MSG_CHECKING([for MinGW inet_ntop()/inet_pton()])
+	AC_LINK_IFELSE(
+		[AC_LANG_PROGRAM(
+			[[
+#include <ws2tcpip.h>
+			]],
+			[[
+int r = (int) inet_ntop (0, NULL, NULL, 0);
+    r += inet_pton(AF_INET, NULL, NULL);
+return r;
+			]]
+		)],
+		[AC_MSG_RESULT([OK])
+		 AC_DEFINE([HAVE_INET_NTOP],[1],[MinGW inet_ntop])
+		 AC_DEFINE([HAVE_INET_PTON],[1],[MinGW inet_pton])
+		],
+		[AC_MSG_RESULT([not found])]
+	)
+	m4_foreach(
+		[F],
+		m4_split(SOCKET_FUNCS SOCKET_OPT_FUNCS),
+			m4_define([UF], [[m4_join([_], [HAVE], m4_toupper(F))]])
+			AC_DEFINE([UF], [1], [Win32 builtin])
+	)
+else
+	AC_CHECK_FUNCS([inet_ntop inet_pton])
+	AC_CHECK_FUNCS(
+		SOCKET_FUNCS,
+		,
+		[AC_MSG_ERROR([Required library function not found])]
+	)
+	AC_CHECK_FUNCS(SOCKET_OPT_FUNCS)
+fi
+LIBS="${old_LIBS}"
+
+# we assume res_init() always exist, but need to find out *where*...
+AC_SEARCH_LIBS(__res_init, resolv bind, ,
+    AC_SEARCH_LIBS(res_9_init, resolv bind, ,
+	AC_SEARCH_LIBS(res_init, resolv bind, , )))
+
+AC_ARG_VAR([TAP_CFLAGS], [C compiler flags for tap])
+old_CFLAGS="${CFLAGS}"
+CFLAGS="${CFLAGS} ${TAP_CFLAGS}"
+AC_CHECK_HEADERS(
+	[ \
+		net/if_tun.h net/tun/if_tun.h \
+		linux/if_tun.h \
+		tap-windows.h \
+	],
+	[have_tap_header="yes"]
+)
+AC_CHECK_DECLS(
+	[TUNSETPERSIST],
+	[AC_DEFINE([ENABLE_FEATURE_TUN_PERSIST], [1], [We have persist tun capability])],
+	,
+	[[
+		#ifdef HAVE_LINUX_IF_TUN_H
+		#include <linux/if_tun.h>
+		#endif
+	]]
+)
+CFLAGS="${old_CFLAGS}"
+test "${have_tap_header}" = "yes" || AC_MSG_ERROR([no tap header could be found])
+
+AC_CHECK_LIB(
+	[selinux],
+	[setcon],
+	[SELINUX_LIBS="-lselinux"]
+)
+AC_SUBST([SELINUX_LIBS])
+
+AC_ARG_VAR([LIBPAM_CFLAGS], [C compiler flags for libpam])
+AC_ARG_VAR([LIBPAM_LIBS], [linker flags for libpam])
+if test -z "${LIBPAM_LIBS}"; then
+	AC_CHECK_LIB(
+		[pam],
+		[pam_start],
+		[LIBPAM_LIBS="-lpam"]
+	)
+fi
+
+case "${with_mem_check}" in
+	valgrind)
+		AC_CHECK_HEADERS(
+			[valgrind/memcheck.h],
+			[
+				CFLAGS="${CFLAGS} -g -fno-inline"
+				AC_DEFINE(
+					[USE_VALGRIND],
+					[1],
+					[Use valgrind memory debugging library]
+				)
+			],
+			[AC_MSG_ERROR([valgrind headers not found.])]
+		)
+		;;
+	dmalloc)
+		AC_CHECK_HEADERS(
+			[dmalloc.h],
+			[AC_CHECK_LIB(
+				[dmalloc],
+				[malloc],
+				[
+					LIBS="${LIBS} -ldmalloc"
+					AC_DEFINE(
+						[DMALLOC],
+						[1],
+						[Use dmalloc memory debugging library]
+					)
+				],
+				[AC_MSG_ERROR([dmalloc library not found.])]
+			)],
+			[AC_MSG_ERROR([dmalloc headers not found.])]
+		)
+		;;
+	ssl)
+		AC_CHECK_LIB(
+			[ssl],
+			[CRYPTO_mem_ctrl],
+			[
+				AC_DEFINE(
+					[CRYPTO_MDEBUG],
+					[1],
+					[Use memory debugging function in OpenSSL]
+				)
+				AC_MSG_NOTICE([NOTE: OpenSSL library must be compiled with CRYPTO_MDEBUG])
+			],
+			[AC_MSG_ERROR([Memory Debugging function in OpenSSL library not found.])]
+		)
+		;;
+esac
+
+PKG_CHECK_MODULES(
+	[PKCS11_HELPER],
+	[libpkcs11-helper-1 >= 1.11],
+	[have_pkcs11_helper="yes"],
+	[]
+)
+
+if test "${enable_crypto}" = "yes" -a "${with_crypto_library}" = "openssl"; then
+	AC_ARG_VAR([OPENSSL_CFLAGS], [C compiler flags for OpenSSL])
+	AC_ARG_VAR([OPENSSL_LIBS], [linker flags for OpenSSL])
+
+	if test -z "${OPENSSL_CFLAGS}" -a -z "${OPENSSL_LIBS}"; then
+		# if the user did not explicitly specify flags, try to autodetect
+		PKG_CHECK_MODULES(
+			[OPENSSL],
+			[libcrypto >= 0.9.8, libssl >= 0.9.8],
+	        [have_openssl="yes"],
+			[have_openssl="no"] # Provide if-not-found to prevent erroring out
+		)
+
+		OPENSSL_LIBS=${OPENSSL_LIBS:--lssl -lcrypto}
+	fi
+
+	saved_CFLAGS="${CFLAGS}"
+	saved_LIBS="${LIBS}"
+	CFLAGS="${CFLAGS} ${OPENSSL_CFLAGS}"
+	LIBS="${LIBS} ${OPENSSL_LIBS}"
+
+	AC_CHECK_FUNCS([SSL_CTX_new EVP_CIPHER_CTX_set_key_length],
+				   ,
+				   [AC_MSG_ERROR([openssl check failed])]
+	)
+
+	have_openssl_engine="yes"
+	AC_CHECK_FUNCS(
+		[ \
+			ENGINE_load_builtin_engines \
+			ENGINE_register_all_complete \
+			ENGINE_cleanup \
+		],
+		,
+		[have_openssl_engine="no"; break]
+	)
+	if test "${have_openssl_engine}" = "no"; then
+		AC_CHECK_DECL( [ENGINE_cleanup], [have_openssl_engine="yes"],,
+			[[
+				#include <openssl/engine.h>
+			]]
+		)
+	fi
+	if test "${have_openssl_engine}" = "yes"; then
+		AC_DEFINE([HAVE_OPENSSL_ENGINE], [1], [OpenSSL engine support available])
+	fi
+
+	have_crypto_aead_modes="yes"
+	AC_CHECK_FUNCS(
+		[EVP_aes_256_gcm],
+		,
+		[have_crypto_aead_modes="no"; break]
+	)
+
+	AC_CHECK_FUNCS(
+		[ \
+			HMAC_CTX_new \
+			HMAC_CTX_free \
+			HMAC_CTX_reset \
+			EVP_MD_CTX_new \
+			EVP_MD_CTX_free \
+			EVP_MD_CTX_reset \
+			EVP_CIPHER_CTX_reset \
+			SSL_CTX_get_default_passwd_cb \
+			SSL_CTX_get_default_passwd_cb_userdata \
+			SSL_CTX_set_security_level \
+			X509_get0_notBefore \
+			X509_get0_notAfter \
+			X509_get0_pubkey \
+			X509_STORE_get0_objects \
+			X509_OBJECT_free \
+			X509_OBJECT_get_type \
+			EVP_PKEY_id \
+			EVP_PKEY_get0_RSA \
+			EVP_PKEY_get0_DSA \
+			EVP_PKEY_get0_EC_KEY \
+			RSA_set_flags \
+			RSA_bits \
+			RSA_get0_key \
+			RSA_set0_key \
+			DSA_get0_pqg \
+			DSA_bits \
+			RSA_meth_new \
+			RSA_meth_free \
+			RSA_meth_set_pub_enc \
+			RSA_meth_set_pub_dec \
+			RSA_meth_set_priv_enc \
+			RSA_meth_set_priv_dec \
+			RSA_meth_set_init \
+			RSA_meth_set_sign \
+			RSA_meth_set_finish \
+			RSA_meth_set0_app_data \
+			RSA_meth_get0_app_data \
+			EC_GROUP_order_bits
+		]
+	)
+
+	CFLAGS="${saved_CFLAGS}"
+	LIBS="${saved_LIBS}"
+
+	have_crypto="yes"
+	AC_DEFINE([ENABLE_CRYPTO_OPENSSL], [1], [Use OpenSSL library])
+	CRYPTO_CFLAGS="${OPENSSL_CFLAGS}"
+	CRYPTO_LIBS="${OPENSSL_LIBS}"
+elif test "${enable_crypto}" = "yes" -a "${with_crypto_library}" = "mbedtls"; then
+	AC_ARG_VAR([MBEDTLS_CFLAGS], [C compiler flags for mbedtls])
+	AC_ARG_VAR([MBEDTLS_LIBS], [linker flags for mbedtls])
+
+	saved_CFLAGS="${CFLAGS}"
+	saved_LIBS="${LIBS}"
+
+	if test -z "${MBEDTLS_CFLAGS}" -a -z "${MBEDTLS_LIBS}"; then
+		# if the user did not explicitly specify flags, try to autodetect
+		LIBS="${LIBS} -lmbedtls -lmbedx509 -lmbedcrypto"
+		AC_CHECK_LIB(
+			[mbedtls],
+			[mbedtls_ssl_init],
+			[MBEDTLS_LIBS="-lmbedtls -lmbedx509 -lmbedcrypto"],
+			[AC_MSG_ERROR([Could not find mbed TLS.])],
+			[${PKCS11_HELPER_LIBS}]
+		)
+	fi
+
+	CFLAGS="${MBEDTLS_CFLAGS} ${PKCS11_HELPER_CFLAGS} ${CFLAGS}"
+	LIBS="${MBEDTLS_LIBS} ${PKCS11_HELPER_LIBS} ${LIBS}"
+
+	AC_MSG_CHECKING([mbedtls version])
+	AC_COMPILE_IFELSE(
+		[AC_LANG_PROGRAM(
+			[[
+#include <mbedtls/version.h>
+			]],
+			[[
+#if MBEDTLS_VERSION_NUMBER < 0x02000000 || MBEDTLS_VERSION_NUMBER >= 0x03000000
+#error invalid version
+#endif
+			]]
+		)],
+		[AC_MSG_RESULT([ok])],
+		[AC_MSG_ERROR([mbed TLS 2.y.z required])]
+	)
+
+	mbedtls_with_pkcs11="no"
+	AC_COMPILE_IFELSE(
+		[AC_LANG_PROGRAM(
+			[[
+#include <mbedtls/config.h>
+			]],
+			[[
+#ifndef MBEDTLS_PKCS11_C
+#error pkcs11 wrapper missing
+#endif
+			]]
+		)],
+		mbedtls_with_pkcs11="yes")
+
+	AC_MSG_CHECKING([mbedtls pkcs11 support])
+	if test "${enable_pkcs11}" = "yes"; then
+		if test "${mbedtls_with_pkcs11}" = "yes"; then
+			AC_MSG_RESULT([ok])
+		else
+			AC_MSG_ERROR([mbedtls has no pkcs11 wrapper compiled in])
+		fi
+	else
+		if test "${mbedtls_with_pkcs11}" != "yes"; then
+			AC_MSG_RESULT([ok])
+		else
+			AC_MSG_ERROR([mbed TLS compiled with PKCS11, while OpenVPN is not])
+		fi
+	fi
+
+	have_crypto_aead_modes="yes"
+	AC_CHECK_FUNCS(
+		[ \
+			mbedtls_cipher_write_tag \
+			mbedtls_cipher_check_tag \
+		],
+		,
+		[have_crypto_aead_modes="no"; break]
+	)
+
+	CFLAGS="${saved_CFLAGS}"
+	LIBS="${saved_LIBS}"
+	have_crypto="yes"
+	AC_DEFINE([ENABLE_CRYPTO_MBEDTLS], [1], [Use mbed TLS library])
+	CRYPTO_CFLAGS="${MBEDTLS_CFLAGS}"
+	CRYPTO_LIBS="${MBEDTLS_LIBS}"
+elif test "${enable_crypto}" = "yes"; then
+	AC_MSG_ERROR([Invalid crypto library: ${with_crypto_library}])
+fi
+
+AC_ARG_VAR([LZO_CFLAGS], [C compiler flags for lzo])
+AC_ARG_VAR([LZO_LIBS], [linker flags for lzo])
+have_lzo="yes"
+if test -z "${LZO_LIBS}"; then
+	AC_CHECK_LIB(
+		[lzo2],
+		[lzo1x_1_15_compress],
+		[LZO_LIBS="-llzo2"],
+		[AC_CHECK_LIB(
+			[lzo],
+			[lzo1x_1_15_compress],
+			[LZO_LIBS="-llzo"],
+			[have_lzo="no"]
+		)]
+	)
+fi
+if test "${have_lzo}" = "yes"; then
+	saved_CFLAGS="${CFLAGS}"
+	CFLAGS="${CFLAGS} ${LZO_CFLAGS}"
+	AC_CHECK_HEADERS(
+		[lzo/lzoutil.h],
+		,
+		[AC_CHECK_HEADERS(
+			[lzoutil.h],
+			,
+			[AC_MSG_ERROR([lzoutil.h is missing])]
+		)]
+	)
+	AC_CHECK_HEADERS(
+		[lzo/lzo1x.h],
+		,
+		[AC_CHECK_HEADERS(
+			[lzo1x.h],
+			,
+			[AC_MSG_ERROR([lzo1x.h is missing])]
+		)]
+	)
+	CFLAGS="${saved_CFLAGS}"
+fi
+
+dnl
+dnl check for LZ4 library
+dnl
+
+AC_ARG_VAR([LZ4_CFLAGS], [C compiler flags for lz4])
+AC_ARG_VAR([LZ4_LIBS], [linker flags for lz4])
+if test "$enable_lz4" = "yes" && test "$enable_comp_stub" = "no"; then
+    if test -z "${LZ4_CFLAGS}" -a -z "${LZ4_LIBS}"; then
+	# if the user did not explicitly specify flags, try to autodetect
+	PKG_CHECK_MODULES([LZ4],
+			  [liblz4 >= 1.7.1 liblz4 < 100],
+			  [have_lz4="yes"],
+			  [LZ4_LIBS="-llz4"] # If this fails, we will do another test next.
+					     # We also add set LZ4_LIBS otherwise the
+					     # linker will not know about the lz4 library
+	)
+    fi
+
+    saved_CFLAGS="${CFLAGS}"
+    saved_LIBS="${LIBS}"
+    CFLAGS="${CFLAGS} ${LZ4_CFLAGS}"
+    LIBS="${LIBS} ${LZ4_LIBS}"
+
+    # If pkgconfig check failed or LZ4_CFLAGS/LZ4_LIBS env vars
+    # are used, check the version directly in the LZ4 include file
+    if test "${have_lz4}" != "yes"; then
+	AC_CHECK_HEADERS([lz4.h],
+			 [have_lz4h="yes"],
+			 [])
+
+	if test "${have_lz4h}" = "yes" ; then
+	    AC_MSG_CHECKING([additionally if system LZ4 version >= 1.7.1])
+	    AC_COMPILE_IFELSE(
+		[AC_LANG_PROGRAM([[
+#include <lz4.h>
+				 ]],
+				 [[
+/* Version encoding: MMNNPP (Major miNor Patch) - see lz4.h for details */
+#if LZ4_VERSION_NUMBER < 10701L
+#error LZ4 is too old
+#endif
+				 ]]
+				)],
+		[
+		    AC_MSG_RESULT([ok])
+		    have_lz4="yes"
+		],
+		[AC_MSG_RESULT([system LZ4 library is too old])]
+	    )
+	fi
+    fi
+
+    # Double check we have a few needed functions
+    if test "${have_lz4}" = "yes" ; then
+	AC_CHECK_LIB([lz4],
+		     [LZ4_compress_default],
+		     [],
+		     [have_lz4="no"])
+	AC_CHECK_LIB([lz4],
+		     [LZ4_decompress_safe],
+		     [],
+		     [have_lz4="no"])
+    fi
+
+    if test "${have_lz4}" != "yes" ; then
+	AC_MSG_RESULT([		usable LZ4 library or header not found, using version in src/compat/compat-lz4.*])
+	AC_DEFINE([NEED_COMPAT_LZ4], [1], [use copy of LZ4 source in compat/])
+	LZ4_LIBS=""
+    fi
+    OPTIONAL_LZ4_CFLAGS="${LZ4_CFLAGS}"
+    OPTIONAL_LZ4_LIBS="${LZ4_LIBS}"
+    AC_DEFINE(ENABLE_LZ4, [1], [Enable LZ4 compression library])
+    CFLAGS="${saved_CFLAGS}"
+    LIBS="${saved_LIBS}"
+fi
+
+
+dnl
+dnl Check for systemd
+dnl
+AM_CONDITIONAL([ENABLE_SYSTEMD], [test "${enable_systemd}" = "yes"])
+if test "$enable_systemd" = "yes" ; then
+    PKG_CHECK_MODULES([libsystemd], [systemd libsystemd],
+                      [],
+                      [PKG_CHECK_MODULES([libsystemd], [libsystemd-daemon])]
+                      )
+
+    PKG_CHECK_EXISTS( [libsystemd > 216],
+                     [AC_DEFINE([SYSTEMD_NEWER_THAN_216], [1],
+                           [systemd is newer than v216])]
+                    )
+
+    AC_CHECK_HEADERS(systemd/sd-daemon.h,
+       ,
+       [
+	   AC_MSG_ERROR([systemd development headers not found.])
+       ])
+
+    saved_LIBS="${LIBS}"
+    LIBS="${LIBS} ${libsystemd_LIBS}"
+    AC_CHECK_FUNCS([sd_booted], [], [AC_MSG_ERROR([systemd library is missing sd_booted()])])
+    OPTIONAL_SYSTEMD_LIBS="${libsystemd_LIBS}"
+    AC_DEFINE(ENABLE_SYSTEMD, 1, [Enable systemd integration])
+    LIBS="${saved_LIBS}"
+
+    if test -n "${SYSTEMD_UNIT_DIR}"; then
+        systemdunitdir="${SYSTEMD_UNIT_DIR}"
+    else
+        systemdunitdir="\${libdir}/systemd/system"
+    fi
+
+    if test -n "${TMPFILES_DIR}"; then
+        tmpfilesdir="${TMPFILES_DIR}"
+    else
+        tmpfilesdir="\${libdir}/tmpfiles.d"
+    fi
+fi
+
+
+AC_MSG_CHECKING([git checkout])
+GIT_CHECKOUT="no"
+if test -n "${GIT}" -a -d "${srcdir}/.git"; then
+	AC_DEFINE([HAVE_CONFIG_VERSION_H], [1], [extra version available in config-version.h])
+	GIT_CHECKOUT="yes"
+fi
+AC_MSG_RESULT([${GIT_CHECKOUT}])
+
+if test -n "${SP_PLATFORM_WINDOWS}"; then
+	AC_DEFINE_UNQUOTED([PATH_SEPARATOR], ['\\\\'], [Path separator]) #"
+	AC_DEFINE_UNQUOTED([PATH_SEPARATOR_STR], ["\\\\"], [Path separator]) #"
+else
+	AC_DEFINE_UNQUOTED([PATH_SEPARATOR], ['/'], [Path separator])
+	AC_DEFINE_UNQUOTED([PATH_SEPARATOR_STR], ["/"], [Path separator])
+fi
+
+dnl enable --x509-username-field feature if requested
+if test "${enable_x509_alt_username}" = "yes"; then
+	if test "${with_crypto_library}" = "mbedtls" ; then
+		AC_MSG_ERROR([mbed TLS does not support the --x509-username-field feature])
+	fi
+
+	AC_DEFINE([ENABLE_X509ALTUSERNAME], [1], [Enable --x509-username-field feature])
+fi
+
+test "${ac_cv_header_sys_uio_h}" = "yes" && AC_DEFINE([HAVE_IOVEC], [1], [struct iovec needed for IPv6 support])
+test "${enable_server}" = "no" && AC_DEFINE([ENABLE_CLIENT_ONLY], [1], [Enable client capability only])
+test "${enable_management}" = "yes" && AC_DEFINE([ENABLE_MANAGEMENT], [1], [Enable management server capability])
+test "${enable_multihome}" = "yes" && AC_DEFINE([ENABLE_MULTIHOME], [1], [Enable multi-homed UDP server capability])
+test "${enable_debug}" = "yes" && AC_DEFINE([ENABLE_DEBUG], [1], [Enable debugging support])
+test "${enable_small}" = "yes" && AC_DEFINE([ENABLE_SMALL], [1], [Enable smaller executable size])
+test "${enable_fragment}" = "yes" && AC_DEFINE([ENABLE_FRAGMENT], [1], [Enable internal fragmentation support])
+test "${enable_port_share}" = "yes" && AC_DEFINE([ENABLE_PORT_SHARE], [1], [Enable TCP Server port sharing])
+test "${enable_def_auth}" = "yes" && AC_DEFINE([ENABLE_DEF_AUTH], [1], [Enable deferred authentication])
+test "${enable_pf}" = "yes" && AC_DEFINE([ENABLE_PF], [1], [Enable internal packet filter])
+test "${enable_strict_options}" = "yes" && AC_DEFINE([ENABLE_STRICT_OPTIONS_CHECK], [1], [Enable strict options check between peers])
+
+if test "${enable_crypto}" = "yes"; then
+	test "${have_crypto}" != "yes" && AC_MSG_ERROR([${with_crypto_library} crypto is required but missing])
+	test "${enable_crypto_ofb_cfb}" = "yes" && AC_DEFINE([ENABLE_OFB_CFB_MODE], [1], [Enable OFB and CFB cipher modes])
+	test "${have_crypto_aead_modes}" = "yes" && AC_DEFINE([HAVE_AEAD_CIPHER_MODES], [1], [Use crypto library])
+	OPTIONAL_CRYPTO_CFLAGS="${OPTIONAL_CRYPTO_CFLAGS} ${CRYPTO_CFLAGS}"
+	OPTIONAL_CRYPTO_LIBS="${OPTIONAL_CRYPTO_LIBS} ${CRYPTO_LIBS}"
+	AC_DEFINE([ENABLE_CRYPTO], [1], [Enable crypto library])
+fi
+
+if test "${enable_plugins}" = "yes"; then
+	OPTIONAL_DL_LIBS="${DL_LIBS}"
+	AC_DEFINE([ENABLE_PLUGIN], [1], [Enable plug-in support])
+else
+	enable_plugin_auth_pam="no"
+	enable_plugin_down_root="no"
+fi
+
+if test "${enable_iproute2}" = "yes"; then
+	test -z "${IPROUTE}" && AC_MSG_ERROR([ip utility is required but missing])
+	AC_DEFINE([ENABLE_IPROUTE], [1], [enable iproute2 support])
+else
+	if test "${WIN32}" != "yes"; then
+		test -z "${ROUTE}" && AC_MSG_ERROR([route utility is required but missing])
+		test -z "${IFCONFIG}" && AC_MSG_ERROR([ifconfig utility is required but missing])
+	fi
+fi
+
+if test "${enable_selinux}" = "yes"; then
+	test -z "${SELINUX_LIBS}" && AC_MSG_ERROR([libselinux required but missing])
+	OPTIONAL_SELINUX_LIBS="${SELINUX_LIBS}"
+	AC_DEFINE([ENABLE_SELINUX], [1], [SELinux support])
+fi
+
+if test "${enable_lzo}" = "yes"; then
+	test "${have_lzo}" != "yes" && AC_MSG_ERROR([lzo enabled but missing])
+	OPTIONAL_LZO_CFLAGS="${LZO_CFLAGS}"
+	OPTIONAL_LZO_LIBS="${LZO_LIBS}"
+	AC_DEFINE([ENABLE_LZO], [1], [Enable LZO compression library])
+fi
+if test "${enable_comp_stub}" = "yes"; then
+	test "${enable_lzo}" = "yes" && AC_MSG_ERROR([Cannot have both comp stub and lzo enabled (use --disable-lzo)])
+	test "${enable_lz4}" = "yes" && AC_MSG_ERROR([Cannot have both comp stub and LZ4 enabled (use --disable-lz4)])
+	AC_DEFINE([ENABLE_COMP_STUB], [1], [Enable compression stub capability])
+fi
+
+if test "${enable_pkcs11}" = "yes"; then
+	test "${have_pkcs11_helper}" != "yes" && AC_MSG_ERROR([PKCS11 enabled but libpkcs11-helper is missing])
+	test "${enable_crypto}" != "yes" && AC_MSG_ERROR([PKCS11 can be enabled only if crypto is enabled])
+	OPTIONAL_PKCS11_HELPER_CFLAGS="${PKCS11_HELPER_CFLAGS}"
+	OPTIONAL_PKCS11_HELPER_LIBS="${PKCS11_HELPER_LIBS}"
+	AC_DEFINE([ENABLE_PKCS11], [1], [Enable PKCS11])
+	PKG_CHECK_MODULES(
+		[P11KIT],
+		[p11-kit-1],
+		[proxy_module="`$PKG_CONFIG --variable=proxy_module p11-kit-1`"
+		 AC_DEFINE_UNQUOTED([DEFAULT_PKCS11_MODULE], "${proxy_module}", [p11-kit proxy])],
+		[]
+	)
+fi
+
+AC_DEFUN([ACL_CHECK_ADD_COMPILE_FLAGS], [
+    old_cflags="$CFLAGS"
+    CFLAGS="$1 $CFLAGS"
+    AC_MSG_CHECKING([whether the compiler acceppts $1])
+    AC_COMPILE_IFELSE([AC_LANG_PROGRAM()], [AC_MSG_RESULT([yes])],
+        [AC_MSG_RESULT([no]); CFLAGS="$old_cflags"])]
+)
+
+ACL_CHECK_ADD_COMPILE_FLAGS([-Wno-unused-function])
+ACL_CHECK_ADD_COMPILE_FLAGS([-Wno-unused-parameter])
+ACL_CHECK_ADD_COMPILE_FLAGS([-Wall])
+
+if test "${enable_pedantic}" = "yes"; then
+	enable_strict="yes"
+	CFLAGS="${CFLAGS} -pedantic"
+	AC_DEFINE([PEDANTIC], [1], [Enable pedantic mode])
+fi
+if test "${enable_strict}" = "yes"; then
+	CFLAGS="${CFLAGS} -Wsign-compare -Wuninitialized"
+fi
+if test "${enable_werror}" = "yes"; then
+	CFLAGS="${CFLAGS} -Werror"
+fi
+
+if test "${enable_plugin_auth_pam}" = "yes"; then
+	PLUGIN_AUTH_PAM_CFLAGS="${LIBPAM_CFLAGS}"
+	if test "${enable_pam_dlopen}" = "yes"; then
+		AC_DEFINE([USE_PAM_DLOPEN], [1], [dlopen libpam])
+		PLUGIN_AUTH_PAM_LIBS="${DL_LIBS}"
+	else
+		test -z "${LIBPAM_LIBS}" && AC_MSG_ERROR([libpam required but missing])
+		PLUGIN_AUTH_PAM_LIBS="${LIBPAM_LIBS}"
+	fi
+fi
+
+if test "${enable_async_push}" = "yes"; then
+	case "$host" in
+		*-*-freebsd*)
+			PKG_CHECK_MODULES(
+				[OPTIONAL_INOTIFY],
+				[libinotify],
+				[
+					AC_DEFINE([HAVE_SYS_INOTIFY_H])
+					AC_DEFINE([ENABLE_ASYNC_PUSH], [1], [Enable async push])
+				]
+			)
+		;;
+		*)
+			AC_CHECK_HEADERS(
+				[sys/inotify.h],
+				AC_DEFINE([ENABLE_ASYNC_PUSH], [1], [Enable async push]),
+				AC_MSG_ERROR([inotify.h not found.])
+			)
+		;;
+	esac
+fi
+
+CONFIGURE_DEFINES="`set | grep '^enable_.*=' ; set | grep '^with_.*='`"
+AC_DEFINE_UNQUOTED([CONFIGURE_DEFINES], ["`echo ${CONFIGURE_DEFINES}`"], [Configuration settings])
+
+TAP_WIN_COMPONENT_ID="PRODUCT_TAP_WIN_COMPONENT_ID"
+TAP_WIN_MIN_MAJOR="PRODUCT_TAP_WIN_MIN_MAJOR"
+TAP_WIN_MIN_MINOR="PRODUCT_TAP_WIN_MIN_MINOR"
+AC_DEFINE_UNQUOTED([TAP_WIN_COMPONENT_ID], ["${TAP_WIN_COMPONENT_ID}"], [The tap-windows id])
+AC_DEFINE_UNQUOTED([TAP_WIN_MIN_MAJOR], [${TAP_WIN_MIN_MAJOR}], [The tap-windows version number is required for OpenVPN])
+AC_DEFINE_UNQUOTED([TAP_WIN_MIN_MINOR], [${TAP_WIN_MIN_MINOR}], [The tap-windows version number is required for OpenVPN])
+AC_SUBST([TAP_WIN_COMPONENT_ID])
+AC_SUBST([TAP_WIN_MIN_MAJOR])
+AC_SUBST([TAP_WIN_MIN_MINOR])
+
+AC_SUBST([OPTIONAL_DL_LIBS])
+AC_SUBST([OPTIONAL_SELINUX_LIBS])
+AC_SUBST([OPTIONAL_CRYPTO_CFLAGS])
+AC_SUBST([OPTIONAL_CRYPTO_LIBS])
+AC_SUBST([OPTIONAL_LZO_CFLAGS])
+AC_SUBST([OPTIONAL_LZO_LIBS])
+AC_SUBST([OPTIONAL_LZ4_CFLAGS])
+AC_SUBST([OPTIONAL_LZ4_LIBS])
+AC_SUBST([OPTIONAL_SYSTEMD_LIBS])
+AC_SUBST([OPTIONAL_PKCS11_HELPER_CFLAGS])
+AC_SUBST([OPTIONAL_PKCS11_HELPER_LIBS])
+AC_SUBST([OPTIONAL_INOTIFY_CFLAGS])
+AC_SUBST([OPTIONAL_INOTIFY_LIBS])
+
+AC_SUBST([PLUGIN_AUTH_PAM_CFLAGS])
+AC_SUBST([PLUGIN_AUTH_PAM_LIBS])
+
+AM_CONDITIONAL([WIN32], [test "${WIN32}" = "yes"])
+AM_CONDITIONAL([GIT_CHECKOUT], [test "${GIT_CHECKOUT}" = "yes"])
+AM_CONDITIONAL([ENABLE_PLUGIN_AUTH_PAM], [test "${enable_plugin_auth_pam}" = "yes"])
+AM_CONDITIONAL([ENABLE_PLUGIN_DOWN_ROOT], [test "${enable_plugin_down_root}" = "yes"])
+AM_CONDITIONAL([ENABLE_CRYPTO], [test "${enable_crypto}" = "yes"])
+AM_CONDITIONAL([HAVE_LD_WRAP_SUPPORT], [test "${have_ld_wrap_support}" = "yes"])
+
+sampledir="\$(docdir)/sample"
+AC_SUBST([plugindir])
+AC_SUBST([sampledir])
+
+AC_SUBST([systemdunitdir])
+AC_SUBST([tmpfilesdir])
+
+TEST_LDFLAGS="${OPTIONAL_CRYPTO_LIBS} ${OPTIONAL_PKCS11_HELPER_LIBS} -lcmocka -L\$(top_builddir)/vendor/dist/lib -Wl,-rpath,\$(top_builddir)/vendor/dist/lib"
+TEST_CFLAGS="${OPTIONAL_CRYPTO_CFLAGS} ${OPTIONAL_PKCS11_HELPER_CFLAGS} -I\$(top_srcdir)/include -I\$(top_builddir)/vendor/dist/include"
+
+AC_SUBST([TEST_LDFLAGS])
+AC_SUBST([TEST_CFLAGS])
+
+# Check if cmake is available and cmocka git submodule is initialized,
+# needed for unit testing
+AC_CHECK_PROGS([CMAKE], [cmake])
+if test -n "${CMAKE}"; then
+   if test -f "${srcdir}/vendor/cmocka/CMakeLists.txt"; then
+      AM_CONDITIONAL([CMOCKA_INITIALIZED], [true])
+   else
+      AM_CONDITIONAL([CMOCKA_INITIALIZED], [false])
+      AC_MSG_RESULT([!! WARNING !! The cmoka git submodule has not been initialized or updated.  Unit testing cannot be performed.])
+   fi
+else
+   AC_MSG_RESULT([!! WARNING !! CMake is NOT available.  Unit testing cannot be performed.])
+   AM_CONDITIONAL([CMOCKA_INITIALIZED], [false])
+fi
+
+
+AC_CONFIG_FILES([
+	version.sh
+	Makefile
+	include/Makefile
+	src/Makefile
+	src/compat/Makefile
+	src/openvpn/Makefile
+	src/plugins/Makefile
+	src/plugins/down-root/Makefile
+])
+AC_OUTPUT
diff --git a/include/Makefile.am b/include/Makefile.am
new file mode 100644
index 0000000..484e4e1
--- /dev/null
+++ b/include/Makefile.am
@@ -0,0 +1,18 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in \
+	$(srcdir)/openvpn-plugin.h.in
+
+include_HEADERS = \
+	openvpn-plugin.h \
+	openvpn-msg.h
diff --git a/include/openvpn-msg.h b/include/openvpn-msg.h
new file mode 100644
index 0000000..66177a2
--- /dev/null
+++ b/include/openvpn-msg.h
@@ -0,0 +1,120 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2013-2018 Heiko Hund <heiko.hund@sophos.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_MSG_H_
+#define OPENVPN_MSG_H_
+
+typedef enum {
+    msg_acknowledgement,
+    msg_add_address,
+    msg_del_address,
+    msg_add_route,
+    msg_del_route,
+    msg_add_dns_cfg,
+    msg_del_dns_cfg,
+    msg_add_nbt_cfg,
+    msg_del_nbt_cfg,
+    msg_flush_neighbors,
+    msg_add_block_dns,
+    msg_del_block_dns,
+    msg_register_dns,
+    msg_enable_dhcp,
+} message_type_t;
+
+typedef struct {
+    message_type_t type;
+    size_t size;
+    int message_id;
+} message_header_t;
+
+typedef union {
+    struct in_addr ipv4;
+    struct in6_addr ipv6;
+} inet_address_t;
+
+typedef struct {
+    int index;
+    char name[256];
+} interface_t;
+
+typedef struct {
+    message_header_t header;
+    short family;
+    inet_address_t address;
+    int prefix_len;
+    interface_t iface;
+} address_message_t;
+
+typedef struct {
+    message_header_t header;
+    short family;
+    inet_address_t prefix;
+    int prefix_len;
+    inet_address_t gateway;
+    interface_t iface;
+    int metric;
+} route_message_t;
+
+typedef struct {
+    message_header_t header;
+    interface_t iface;
+    char domains[512];
+    short family;
+    int addr_len;
+    inet_address_t addr[4]; /* support up to 4 dns addresses */
+} dns_cfg_message_t;
+
+typedef struct {
+    message_header_t header;
+    interface_t iface;
+    int disable_nbt;
+    int nbt_type;
+    char scope_id[256];
+    struct in_addr primary_nbns;
+    struct in_addr secondary_nbns;
+} nbt_cfg_message_t;
+
+/* TODO: NTP */
+
+typedef struct {
+    message_header_t header;
+    short family;
+    interface_t iface;
+} flush_neighbors_message_t;
+
+typedef struct {
+    message_header_t header;
+    int error_number;
+} ack_message_t;
+
+typedef struct {
+    message_header_t header;
+    interface_t iface;
+} block_dns_message_t;
+
+typedef struct {
+    message_header_t header;
+    interface_t iface;
+} enable_dhcp_message_t;
+
+#endif /* ifndef OPENVPN_MSG_H_ */
diff --git a/include/openvpn-plugin.h b/include/openvpn-plugin.h
new file mode 100644
index 0000000..0a9f3fe
--- /dev/null
+++ b/include/openvpn-plugin.h
@@ -0,0 +1,871 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_PLUGIN_H_
+#define OPENVPN_PLUGIN_H_
+
+#define OPENVPN_PLUGIN_VERSION 3
+
+#ifdef ENABLE_CRYPTO
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include <mbedtls/x509_crt.h>
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef mbedtls_x509_crt openvpn_x509_cert_t;
+#endif
+#else  /* ifdef ENABLE_CRYPTO_MBEDTLS */
+#include <openssl/x509.h>
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef X509 openvpn_x509_cert_t;
+#endif
+#endif
+#endif
+
+#include <stdarg.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Plug-in types.  These types correspond to the set of script callbacks
+ * supported by OpenVPN.
+ *
+ * This is the general call sequence to expect when running in server mode:
+ *
+ * Initial Server Startup:
+ *
+ * FUNC: openvpn_plugin_open_v1
+ * FUNC: openvpn_plugin_client_constructor_v1 (this is the top-level "generic"
+ *                                             client template)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_UP
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ROUTE_UP
+ *
+ * New Client Connection:
+ *
+ * FUNC: openvpn_plugin_client_constructor_v1
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert
+ *                                                     in the server chain)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_IPCHANGE
+ *
+ * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,
+ * we don't proceed until authentication is verified via auth_control_file]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_CONNECT_V2
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS
+ *
+ * [Client session ensues]
+ *
+ * For each "TLS soft reset", according to reneg-sec option (or similar):
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert
+ *                                                     in the server chain)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
+ *
+ * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,
+ * we expect that authentication is verified via auth_control_file within
+ * the number of seconds defined by the "hand-window" option.  Data channel traffic
+ * will continue to flow uninterrupted during this period.]
+ *
+ * [Client session continues]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_DISCONNECT
+ * FUNC: openvpn_plugin_client_destructor_v1
+ *
+ * [ some time may pass ]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS (this coincides with a
+ *                                                            lazy free of initial
+ *                                                            learned addr object)
+ * Server Shutdown:
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_DOWN
+ * FUNC: openvpn_plugin_client_destructor_v1 (top-level "generic" client)
+ * FUNC: openvpn_plugin_close_v1
+ */
+#define OPENVPN_PLUGIN_UP                    0
+#define OPENVPN_PLUGIN_DOWN                  1
+#define OPENVPN_PLUGIN_ROUTE_UP              2
+#define OPENVPN_PLUGIN_IPCHANGE              3
+#define OPENVPN_PLUGIN_TLS_VERIFY            4
+#define OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY 5
+#define OPENVPN_PLUGIN_CLIENT_CONNECT        6
+#define OPENVPN_PLUGIN_CLIENT_DISCONNECT     7
+#define OPENVPN_PLUGIN_LEARN_ADDRESS         8
+#define OPENVPN_PLUGIN_CLIENT_CONNECT_V2     9
+#define OPENVPN_PLUGIN_TLS_FINAL             10
+#define OPENVPN_PLUGIN_ENABLE_PF             11
+#define OPENVPN_PLUGIN_ROUTE_PREDOWN         12
+#define OPENVPN_PLUGIN_N                     13
+
+/*
+ * Build a mask out of a set of plug-in types.
+ */
+#define OPENVPN_PLUGIN_MASK(x) (1<<(x))
+
+/*
+ * A pointer to a plugin-defined object which contains
+ * the object state.
+ */
+typedef void *openvpn_plugin_handle_t;
+
+/*
+ * Return value for openvpn_plugin_func_v1 function
+ */
+#define OPENVPN_PLUGIN_FUNC_SUCCESS  0
+#define OPENVPN_PLUGIN_FUNC_ERROR    1
+#define OPENVPN_PLUGIN_FUNC_DEFERRED 2
+
+/*
+ * For Windows (needs to be modified for MSVC)
+ */
+#if defined(_WIN32) && !defined(OPENVPN_PLUGIN_H)
+#define OPENVPN_EXPORT __declspec(dllexport)
+#else
+#define OPENVPN_EXPORT
+#endif
+
+/*
+ * If OPENVPN_PLUGIN_H is defined, we know that we are being
+ * included in an OpenVPN compile, rather than a plugin compile.
+ */
+#ifdef OPENVPN_PLUGIN_H
+
+/*
+ * We are compiling OpenVPN.
+ */
+#define OPENVPN_PLUGIN_DEF        typedef
+#define OPENVPN_PLUGIN_FUNC(name) (*name)
+
+#else  /* ifdef OPENVPN_PLUGIN_H */
+
+/*
+ * We are compiling plugin.
+ */
+#define OPENVPN_PLUGIN_DEF        OPENVPN_EXPORT
+#define OPENVPN_PLUGIN_FUNC(name) name
+
+#endif
+
+/*
+ * Used by openvpn_plugin_func to return structured
+ * data.  The plugin should allocate all structure
+ * instances, name strings, and value strings with
+ * malloc, since OpenVPN will assume that it
+ * can free the list by calling free() over the same.
+ */
+struct openvpn_plugin_string_list
+{
+    struct openvpn_plugin_string_list *next;
+    char *name;
+    char *value;
+};
+
+
+/* openvpn_plugin_{open,func}_v3() related structs */
+
+/**
+ * Defines version of the v3 plugin argument structs
+ *
+ * Whenever one or more of these structs are modified, this constant
+ * must be updated.  A changelog should be appended in this comment
+ * as well, to make it easier to see what information is available
+ * in the different versions.
+ *
+ * Version   Comment
+ *    1      Initial plugin v3 structures providing the same API as
+ *           the v2 plugin interface, X509 certificate information +
+ *           a logging API for plug-ins.
+ *
+ *    2      Added ssl_api member in struct openvpn_plugin_args_open_in
+ *           which identifies the SSL implementation OpenVPN is compiled
+ *           against.
+ *
+ *    3      Added ovpn_version, ovpn_version_major, ovpn_version_minor
+ *           and ovpn_version_patch to provide the runtime version of
+ *           OpenVPN to plug-ins.
+ *
+ *    4      Exported secure_memzero() as plugin_secure_memzero()
+ *
+ *    5      Exported openvpn_base64_encode() as plugin_base64_encode()
+ *           Exported openvpn_base64_decode() as plugin_base64_decode()
+ */
+#define OPENVPN_PLUGINv3_STRUCTVER 5
+
+/**
+ * Definitions needed for the plug-in callback functions.
+ */
+typedef enum
+{
+    PLOG_ERR    = (1 << 0),/* Error condition message */
+    PLOG_WARN   = (1 << 1),/* General warning message */
+    PLOG_NOTE   = (1 << 2),/* Informational message */
+    PLOG_DEBUG  = (1 << 3),/* Debug message, displayed if verb >= 7 */
+
+    PLOG_ERRNO  = (1 << 8),/* Add error description to message */
+    PLOG_NOMUTE = (1 << 9), /* Mute setting does not apply for message */
+
+} openvpn_plugin_log_flags_t;
+
+
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+#define _ovpn_chk_fmt(a, b) __attribute__ ((format(gnu_printf, (a), (b))))
+#else
+#define _ovpn_chk_fmt(a, b) __attribute__ ((format(__printf__, (a), (b))))
+#endif
+#else  /* ifdef __GNUC__ */
+#define _ovpn_chk_fmt(a, b)
+#endif
+
+typedef void (*plugin_log_t)(openvpn_plugin_log_flags_t flags,
+                             const char *plugin_name,
+                             const char *format, ...) _ovpn_chk_fmt (3, 4);
+
+typedef void (*plugin_vlog_t)(openvpn_plugin_log_flags_t flags,
+                              const char *plugin_name,
+                              const char *format,
+                              va_list arglist) _ovpn_chk_fmt (3, 0);
+#undef _ovpn_chk_fmt
+
+/**
+ *  Export of secure_memzero() to be used inside plug-ins
+ *
+ *  @param data   Pointer to data to zeroise
+ *  @param len    Length of data, in bytes
+ *
+ */
+typedef void (*plugin_secure_memzero_t)(void *data, size_t len);
+
+/**
+ *  Export of openvpn_base64_encode() to be used inside plug-ins
+ *
+ *  @param data   Pointer to data to BASE64 encode
+ *  @param size   Length of data, in bytes
+ *  @param *str   Pointer to the return buffer.  This needed memory is
+ *                allocated by openvpn_base64_encode() and needs to be free()d
+ *                after use.
+ *
+ *  @return int   Returns the length of the buffer created, or -1 on error.
+ *
+ */
+typedef int (*plugin_base64_encode_t)(const void *data, int size, char **str);
+
+/**
+ *  Export of openvpn_base64_decode() to be used inside plug-ins
+ *
+ *  @param str    Pointer to the BASE64 encoded data
+ *  @param data   Pointer to the buffer where save the decoded data
+ *  @param size   Size of the destination buffer
+ *
+ *  @return int   Returns the length of the decoded data, or -1 on error or
+ *                if the destination buffer is too small.
+ *
+ */
+typedef int (*plugin_base64_decode_t)(const char *str, void *data, int size);
+
+
+/**
+ * Used by the openvpn_plugin_open_v3() function to pass callback
+ * function pointers to the plug-in.
+ *
+ * plugin_log
+ * plugin_vlog : Use these functions to add information to the OpenVPN log file.
+ *               Messages will only be displayed if the plugin_name parameter
+ *               is set. PLOG_DEBUG messages will only be displayed with plug-in
+ *               debug log verbosity (at the time of writing that's verb >= 7).
+ *
+ * plugin_secure_memzero
+ *             : Use this function to securely wipe sensitive information from
+ *               memory.  This function is declared in a way that the compiler
+ *               will not remove these function calls during the compiler
+ *               optimization phase.
+ */
+struct openvpn_plugin_callbacks
+{
+    plugin_log_t plugin_log;
+    plugin_vlog_t plugin_vlog;
+    plugin_secure_memzero_t plugin_secure_memzero;
+    plugin_base64_encode_t plugin_base64_encode;
+    plugin_base64_decode_t plugin_base64_decode;
+};
+
+/**
+ * Used by the openvpn_plugin_open_v3() function to indicate to the
+ * plug-in what kind of SSL implementation OpenVPN uses.  This is
+ * to avoid SEGV issues when OpenVPN is complied against mbed TLS
+ * and the plug-in against OpenSSL.
+ */
+typedef enum {
+    SSLAPI_NONE,
+    SSLAPI_OPENSSL,
+    SSLAPI_MBEDTLS
+} ovpnSSLAPI;
+
+/**
+ * Arguments used to transport variables to the plug-in.
+ * The struct openvpn_plugin_args_open_in is only used
+ * by the openvpn_plugin_open_v3() function.
+ *
+ * STRUCT MEMBERS
+ *
+ * type_mask : Set by OpenVPN to the logical OR of all script
+ *             types which this version of OpenVPN supports.
+ *
+ * argv : a NULL-terminated array of options provided to the OpenVPN
+ *        "plug-in" directive.  argv[0] is the dynamic library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * callbacks : a pointer to the plug-in callback function struct.
+ *
+ */
+struct openvpn_plugin_args_open_in
+{
+    const int type_mask;
+    const char **const argv;
+    const char **const envp;
+    struct openvpn_plugin_callbacks *callbacks;
+    const ovpnSSLAPI ssl_api;
+    const char *ovpn_version;
+    const unsigned int ovpn_version_major;
+    const unsigned int ovpn_version_minor;
+    const char *const ovpn_version_patch;
+};
+
+
+/**
+ * Arguments used to transport variables from the plug-in back
+ * to the OpenVPN process.  The struct openvpn_plugin_args_open_return
+ * is only used by the openvpn_plugin_open_v3() function.
+ *
+ * STRUCT MEMBERS
+ *
+ * type_mask  : The plug-in should set this value to the logical OR of all script
+ *              types which the plug-in wants to intercept.  For example, if the
+ *              script wants to intercept the client-connect and client-disconnect
+ *              script types:
+ *
+ *              type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT)
+ *                         | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT)
+ *
+ * handle :     Pointer to a global plug-in context, created by the plug-in.  This pointer
+ *              is passed on to the other plug-in calls.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ */
+struct openvpn_plugin_args_open_return
+{
+    int type_mask;
+    openvpn_plugin_handle_t handle;
+    struct openvpn_plugin_string_list **return_list;
+};
+
+/**
+ * Arguments used to transport variables to and from the
+ * plug-in.  The struct openvpn_plugin_args_func is only used
+ * by the openvpn_plugin_func_v3() function.
+ *
+ * STRUCT MEMBERS:
+ *
+ * type : one of the PLUGIN_x types.
+ *
+ * argv : a NULL-terminated array of "command line" options which
+ *        would normally be passed to the script.  argv[0] is the dynamic
+ *        library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * handle : Pointer to a global plug-in context, created by the plug-in's openvpn_plugin_open_v3().
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ *
+ * current_cert_depth : Certificate depth of the certificate being passed over (only if compiled with ENABLE_CRYPTO defined)
+ *
+ * *current_cert : X509 Certificate object received from the client (only if compiled with ENABLE_CRYPTO defined)
+ *
+ */
+struct openvpn_plugin_args_func_in
+{
+    const int type;
+    const char **const argv;
+    const char **const envp;
+    openvpn_plugin_handle_t handle;
+    void *per_client_context;
+#ifdef ENABLE_CRYPTO
+    int current_cert_depth;
+    openvpn_x509_cert_t *current_cert;
+#else
+    int __current_cert_depth_disabled; /* Unused, for compatibility purposes only */
+    void *__current_cert_disabled; /* Unused, for compatibility purposes only */
+#endif
+};
+
+
+/**
+ * Arguments used to transport variables to and from the
+ * plug-in.  The struct openvpn_plugin_args_func is only used
+ * by the openvpn_plugin_func_v3() function.
+ *
+ * STRUCT MEMBERS:
+ *
+ * return_list : used to return data back to OpenVPN for further processing/usage by
+ *               the OpenVPN executable.
+ *
+ */
+struct openvpn_plugin_args_func_return
+{
+    struct openvpn_plugin_string_list **return_list;
+};
+
+/*
+ * Multiple plugin modules can be cascaded, and modules can be
+ * used in tandem with scripts.  The order of operation is that
+ * the module func() functions are called in the order that
+ * the modules were specified in the config file.  If a script
+ * was specified as well, it will be called last.  If the
+ * return code of the module/script controls an authentication
+ * function (such as tls-verify or auth-user-pass-verify), then
+ * every module and script must return success (0) in order for
+ * the connection to be authenticated.
+ *
+ * Notes:
+ *
+ * Plugins which use a privilege-separation model (by forking in
+ * their initialization function before the main OpenVPN process
+ * downgrades root privileges and/or executes a chroot) must
+ * daemonize after a fork if the "daemon" environmental variable is
+ * set.  In addition, if the "daemon_log_redirect" variable is set,
+ * the plugin should preserve stdout/stderr across the daemon()
+ * syscall.  See the daemonize() function in plugin/auth-pam/auth-pam.c
+ * for an example.
+ */
+
+/*
+ * Prototypes for functions which OpenVPN plug-ins must define.
+ */
+
+/*
+ * FUNCTION: openvpn_plugin_open_v2
+ *
+ * REQUIRED: YES
+ *
+ * Called on initial plug-in load.  OpenVPN will preserve plug-in state
+ * across SIGUSR1 restarts but not across SIGHUP restarts.  A SIGHUP reset
+ * will cause the plugin to be closed and reopened.
+ *
+ * ARGUMENTS
+ *
+ * *type_mask : Set by OpenVPN to the logical OR of all script
+ *              types which this version of OpenVPN supports.  The plug-in
+ *              should set this value to the logical OR of all script types
+ *              which the plug-in wants to intercept.  For example, if the
+ *              script wants to intercept the client-connect and
+ *              client-disconnect script types:
+ *
+ *              *type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT)
+ *                         | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT)
+ *
+ * argv : a NULL-terminated array of options provided to the OpenVPN
+ *        "plug-in" directive.  argv[0] is the dynamic library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * An openvpn_plugin_handle_t value on success, NULL on failure
+ */
+OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v2)
+    (unsigned int *type_mask,
+    const char *argv[],
+    const char *envp[],
+    struct openvpn_plugin_string_list **return_list);
+
+/*
+ * FUNCTION: openvpn_plugin_func_v2
+ *
+ * Called to perform the work of a given script type.
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * type : one of the PLUGIN_x types
+ *
+ * argv : a NULL-terminated array of "command line" options which
+ *        would normally be passed to the script.  argv[0] is the dynamic
+ *        library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ *
+ * In addition, OPENVPN_PLUGIN_FUNC_DEFERRED may be returned by
+ * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY.  This enables asynchronous
+ * authentication where the plugin (or one of its agents) may indicate
+ * authentication success/failure some number of seconds after the return
+ * of the OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY handler by writing a single
+ * char to the file named by auth_control_file in the environmental variable
+ * list (envp).
+ *
+ * first char of auth_control_file:
+ * '0' -- indicates auth failure
+ * '1' -- indicates auth success
+ *
+ * OpenVPN will delete the auth_control_file after it goes out of scope.
+ *
+ * If an OPENVPN_PLUGIN_ENABLE_PF handler is defined and returns success
+ * for a particular client instance, packet filtering will be enabled for that
+ * instance.  OpenVPN will then attempt to read the packet filter configuration
+ * from the temporary file named by the environmental variable pf_file.  This
+ * file may be generated asynchronously and may be dynamically updated during the
+ * client session, however the client will be blocked from sending or receiving
+ * VPN tunnel packets until the packet filter file has been generated.  OpenVPN
+ * will periodically test the packet filter file over the life of the client
+ * instance and reload when modified.  OpenVPN will delete the packet filter file
+ * when the client instance goes out of scope.
+ *
+ * Packet filter file grammar:
+ *
+ * [CLIENTS DROP|ACCEPT]
+ * {+|-}common_name1
+ * {+|-}common_name2
+ * . . .
+ * [SUBNETS DROP|ACCEPT]
+ * {+|-}subnet1
+ * {+|-}subnet2
+ * . . .
+ * [END]
+ *
+ * Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS
+ *
+ * CLIENTS refers to the set of clients (by their common-name) which
+ * this instance is allowed ('+') to connect to, or is excluded ('-')
+ * from connecting to.  Note that in the case of client-to-client
+ * connections, such communication must be allowed by the packet filter
+ * configuration files of both clients.
+ *
+ * SUBNETS refers to IP addresses or IP address subnets which this
+ * instance may connect to ('+') or is excluded ('-') from connecting
+ * to.
+ *
+ * DROP or ACCEPT defines default policy when there is no explicit match
+ * for a common-name or subnet.  The [END] tag must exist.  A special
+ * purpose tag called [KILL] will immediately kill the client instance.
+ * A given client or subnet rule applies to both incoming and outgoing
+ * packets.
+ *
+ * See plugin/defer/simple.c for an example on using asynchronous
+ * authentication and client-specific packet filtering.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v2)
+    (openvpn_plugin_handle_t handle,
+    const int type,
+    const char *argv[],
+    const char *envp[],
+    void *per_client_context,
+    struct openvpn_plugin_string_list **return_list);
+
+
+/*
+ * FUNCTION: openvpn_plugin_open_v3
+ *
+ * REQUIRED: YES
+ *
+ * Called on initial plug-in load.  OpenVPN will preserve plug-in state
+ * across SIGUSR1 restarts but not across SIGHUP restarts.  A SIGHUP reset
+ * will cause the plugin to be closed and reopened.
+ *
+ * ARGUMENTS
+ *
+ * version : fixed value, defines the API version of the OpenVPN plug-in API.  The plug-in
+ *           should validate that this value is matching the OPENVPN_PLUGINv3_STRUCTVER
+ *           value.
+ *
+ * arguments : Structure with all arguments available to the plug-in.
+ *
+ * retptr :    used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v3)
+    (const int version,
+    struct openvpn_plugin_args_open_in const *arguments,
+    struct openvpn_plugin_args_open_return *retptr);
+
+/*
+ * FUNCTION: openvpn_plugin_func_v3
+ *
+ * Called to perform the work of a given script type.
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * version : fixed value, defines the API version of the OpenVPN plug-in API.  The plug-in
+ *           should validate that this value is matching the OPENVPN_PLUGIN_VERSION value.
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ *
+ * In addition, OPENVPN_PLUGIN_FUNC_DEFERRED may be returned by
+ * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY.  This enables asynchronous
+ * authentication where the plugin (or one of its agents) may indicate
+ * authentication success/failure some number of seconds after the return
+ * of the OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY handler by writing a single
+ * char to the file named by auth_control_file in the environmental variable
+ * list (envp).
+ *
+ * first char of auth_control_file:
+ * '0' -- indicates auth failure
+ * '1' -- indicates auth success
+ *
+ * OpenVPN will delete the auth_control_file after it goes out of scope.
+ *
+ * If an OPENVPN_PLUGIN_ENABLE_PF handler is defined and returns success
+ * for a particular client instance, packet filtering will be enabled for that
+ * instance.  OpenVPN will then attempt to read the packet filter configuration
+ * from the temporary file named by the environmental variable pf_file.  This
+ * file may be generated asynchronously and may be dynamically updated during the
+ * client session, however the client will be blocked from sending or receiving
+ * VPN tunnel packets until the packet filter file has been generated.  OpenVPN
+ * will periodically test the packet filter file over the life of the client
+ * instance and reload when modified.  OpenVPN will delete the packet filter file
+ * when the client instance goes out of scope.
+ *
+ * Packet filter file grammar:
+ *
+ * [CLIENTS DROP|ACCEPT]
+ * {+|-}common_name1
+ * {+|-}common_name2
+ * . . .
+ * [SUBNETS DROP|ACCEPT]
+ * {+|-}subnet1
+ * {+|-}subnet2
+ * . . .
+ * [END]
+ *
+ * Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS
+ *
+ * CLIENTS refers to the set of clients (by their common-name) which
+ * this instance is allowed ('+') to connect to, or is excluded ('-')
+ * from connecting to.  Note that in the case of client-to-client
+ * connections, such communication must be allowed by the packet filter
+ * configuration files of both clients.
+ *
+ * SUBNETS refers to IP addresses or IP address subnets which this
+ * instance may connect to ('+') or is excluded ('-') from connecting
+ * to.
+ *
+ * DROP or ACCEPT defines default policy when there is no explicit match
+ * for a common-name or subnet.  The [END] tag must exist.  A special
+ * purpose tag called [KILL] will immediately kill the client instance.
+ * A given client or subnet rule applies to both incoming and outgoing
+ * packets.
+ *
+ * See plugin/defer/simple.c for an example on using asynchronous
+ * authentication and client-specific packet filtering.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v3)
+    (const int version,
+    struct openvpn_plugin_args_func_in const *arguments,
+    struct openvpn_plugin_args_func_return *retptr);
+
+/*
+ * FUNCTION: openvpn_plugin_close_v1
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * Called immediately prior to plug-in unload.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_close_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_abort_v1
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * Called when OpenVPN is in the process of aborting due to a fatal error.
+ * Will only be called on an open context returned by a prior successful
+ * openvpn_plugin_open callback.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_abort_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_client_constructor_v1
+ *
+ * Called to allocate a per-client memory region, which
+ * is then passed to the openvpn_plugin_func_v2 function.
+ * This function is called every time the OpenVPN server
+ * constructs a client instance object, which normally
+ * occurs when a session-initiating packet is received
+ * by a new client, even before the client has authenticated.
+ *
+ * This function should allocate the private memory needed
+ * by the plugin to track individual OpenVPN clients, and
+ * return a void * to this memory region.
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * RETURN VALUE
+ *
+ * void * pointer to plugin's private per-client memory region, or NULL
+ * if no memory region is required.
+ */
+OPENVPN_PLUGIN_DEF void *OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_constructor_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_client_destructor_v1
+ *
+ * This function is called on client instance object destruction.
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_destructor_v1)
+    (openvpn_plugin_handle_t handle, void *per_client_context);
+
+/*
+ * FUNCTION: openvpn_plugin_select_initialization_point_v1
+ *
+ * Several different points exist in OpenVPN's initialization sequence where
+ * the openvpn_plugin_open function can be called.  While the default is
+ * OPENVPN_PLUGIN_INIT_PRE_DAEMON, this function can be used to select a
+ * different initialization point.  For example, if your plugin needs to
+ * return configuration parameters to OpenVPN, use
+ * OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE.
+ *
+ * REQUIRED: NO
+ *
+ * RETURN VALUE:
+ *
+ * An OPENVPN_PLUGIN_INIT_x value.
+ */
+#define OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE 1
+#define OPENVPN_PLUGIN_INIT_PRE_DAEMON       2 /* default */
+#define OPENVPN_PLUGIN_INIT_POST_DAEMON      3
+#define OPENVPN_PLUGIN_INIT_POST_UID_CHANGE  4
+
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_select_initialization_point_v1)
+    (void);
+
+/*
+ * FUNCTION: openvpn_plugin_min_version_required_v1
+ *
+ * This function is called by OpenVPN to query the minimum
+ * plugin interface version number required by the plugin.
+ *
+ * REQUIRED: NO
+ *
+ * RETURN VALUE
+ *
+ * The minimum OpenVPN plugin interface version number necessary to support
+ * this plugin.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_min_version_required_v1)
+    (void);
+
+/*
+ * Deprecated functions which are still supported for backward compatibility.
+ */
+
+OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v1)
+    (unsigned int *type_mask,
+    const char *argv[],
+    const char *envp[]);
+
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v1)
+    (openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[]);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OPENVPN_PLUGIN_H_ */
diff --git a/include/openvpn-plugin.h.in b/include/openvpn-plugin.h.in
new file mode 100644
index 0000000..a604f1c
--- /dev/null
+++ b/include/openvpn-plugin.h.in
@@ -0,0 +1,878 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_PLUGIN_H_
+#define OPENVPN_PLUGIN_H_
+
+#define OPENVPN_PLUGIN_VERSION 3
+
+#ifdef ENABLE_CRYPTO
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include <mbedtls/x509_crt.h>
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef mbedtls_x509_crt openvpn_x509_cert_t;
+#endif
+#else  /* ifdef ENABLE_CRYPTO_MBEDTLS */
+#include <openssl/x509.h>
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef X509 openvpn_x509_cert_t;
+#endif
+#endif
+#endif
+
+#include <stdarg.h>
+#include <stddef.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Provide some basic version information to plug-ins at OpenVPN compile time
+ * This is will not be the complete version
+ */
+#define OPENVPN_VERSION_MAJOR @OPENVPN_VERSION_MAJOR@
+#define OPENVPN_VERSION_MINOR @OPENVPN_VERSION_MINOR@
+#define OPENVPN_VERSION_PATCH "@OPENVPN_VERSION_PATCH@"
+
+/*
+ * Plug-in types.  These types correspond to the set of script callbacks
+ * supported by OpenVPN.
+ *
+ * This is the general call sequence to expect when running in server mode:
+ *
+ * Initial Server Startup:
+ *
+ * FUNC: openvpn_plugin_open_v1
+ * FUNC: openvpn_plugin_client_constructor_v1 (this is the top-level "generic"
+ *                                             client template)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_UP
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ROUTE_UP
+ *
+ * New Client Connection:
+ *
+ * FUNC: openvpn_plugin_client_constructor_v1
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert
+ *                                                     in the server chain)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_IPCHANGE
+ *
+ * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,
+ * we don't proceed until authentication is verified via auth_control_file]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_CONNECT_V2
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS
+ *
+ * [Client session ensues]
+ *
+ * For each "TLS soft reset", according to reneg-sec option (or similar):
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_ENABLE_PF
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_VERIFY (called once for every cert
+ *                                                     in the server chain)
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_TLS_FINAL
+ *
+ * [If OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY returned OPENVPN_PLUGIN_FUNC_DEFERRED,
+ * we expect that authentication is verified via auth_control_file within
+ * the number of seconds defined by the "hand-window" option.  Data channel traffic
+ * will continue to flow uninterrupted during this period.]
+ *
+ * [Client session continues]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_CLIENT_DISCONNECT
+ * FUNC: openvpn_plugin_client_destructor_v1
+ *
+ * [ some time may pass ]
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_LEARN_ADDRESS (this coincides with a
+ *                                                            lazy free of initial
+ *                                                            learned addr object)
+ * Server Shutdown:
+ *
+ * FUNC: openvpn_plugin_func_v1 OPENVPN_PLUGIN_DOWN
+ * FUNC: openvpn_plugin_client_destructor_v1 (top-level "generic" client)
+ * FUNC: openvpn_plugin_close_v1
+ */
+#define OPENVPN_PLUGIN_UP                    0
+#define OPENVPN_PLUGIN_DOWN                  1
+#define OPENVPN_PLUGIN_ROUTE_UP              2
+#define OPENVPN_PLUGIN_IPCHANGE              3
+#define OPENVPN_PLUGIN_TLS_VERIFY            4
+#define OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY 5
+#define OPENVPN_PLUGIN_CLIENT_CONNECT        6
+#define OPENVPN_PLUGIN_CLIENT_DISCONNECT     7
+#define OPENVPN_PLUGIN_LEARN_ADDRESS         8
+#define OPENVPN_PLUGIN_CLIENT_CONNECT_V2     9
+#define OPENVPN_PLUGIN_TLS_FINAL             10
+#define OPENVPN_PLUGIN_ENABLE_PF             11
+#define OPENVPN_PLUGIN_ROUTE_PREDOWN         12
+#define OPENVPN_PLUGIN_N                     13
+
+/*
+ * Build a mask out of a set of plug-in types.
+ */
+#define OPENVPN_PLUGIN_MASK(x) (1<<(x))
+
+/*
+ * A pointer to a plugin-defined object which contains
+ * the object state.
+ */
+typedef void *openvpn_plugin_handle_t;
+
+/*
+ * Return value for openvpn_plugin_func_v1 function
+ */
+#define OPENVPN_PLUGIN_FUNC_SUCCESS  0
+#define OPENVPN_PLUGIN_FUNC_ERROR    1
+#define OPENVPN_PLUGIN_FUNC_DEFERRED 2
+
+/*
+ * For Windows (needs to be modified for MSVC)
+ */
+#if defined(_WIN32) && !defined(OPENVPN_PLUGIN_H)
+#define OPENVPN_EXPORT __declspec(dllexport)
+#else
+#define OPENVPN_EXPORT
+#endif
+
+/*
+ * If OPENVPN_PLUGIN_H is defined, we know that we are being
+ * included in an OpenVPN compile, rather than a plugin compile.
+ */
+#ifdef OPENVPN_PLUGIN_H
+
+/*
+ * We are compiling OpenVPN.
+ */
+#define OPENVPN_PLUGIN_DEF        typedef
+#define OPENVPN_PLUGIN_FUNC(name) (*name)
+
+#else  /* ifdef OPENVPN_PLUGIN_H */
+
+/*
+ * We are compiling plugin.
+ */
+#define OPENVPN_PLUGIN_DEF        OPENVPN_EXPORT
+#define OPENVPN_PLUGIN_FUNC(name) name
+
+#endif
+
+/*
+ * Used by openvpn_plugin_func to return structured
+ * data.  The plugin should allocate all structure
+ * instances, name strings, and value strings with
+ * malloc, since OpenVPN will assume that it
+ * can free the list by calling free() over the same.
+ */
+struct openvpn_plugin_string_list
+{
+    struct openvpn_plugin_string_list *next;
+    char *name;
+    char *value;
+};
+
+
+/* openvpn_plugin_{open,func}_v3() related structs */
+
+/**
+ * Defines version of the v3 plugin argument structs
+ *
+ * Whenever one or more of these structs are modified, this constant
+ * must be updated.  A changelog should be appended in this comment
+ * as well, to make it easier to see what information is available
+ * in the different versions.
+ *
+ * Version   Comment
+ *    1      Initial plugin v3 structures providing the same API as
+ *           the v2 plugin interface, X509 certificate information +
+ *           a logging API for plug-ins.
+ *
+ *    2      Added ssl_api member in struct openvpn_plugin_args_open_in
+ *           which identifies the SSL implementation OpenVPN is compiled
+ *           against.
+ *
+ *    3      Added ovpn_version, ovpn_version_major, ovpn_version_minor
+ *           and ovpn_version_patch to provide the runtime version of
+ *           OpenVPN to plug-ins.
+ *
+ *    4      Exported secure_memzero() as plugin_secure_memzero()
+ *
+ *    5      Exported openvpn_base64_encode() as plugin_base64_encode()
+ *           Exported openvpn_base64_decode() as plugin_base64_decode()
+ */
+#define OPENVPN_PLUGINv3_STRUCTVER 5
+
+/**
+ * Definitions needed for the plug-in callback functions.
+ */
+typedef enum
+{
+    PLOG_ERR    = (1 << 0),/* Error condition message */
+    PLOG_WARN   = (1 << 1),/* General warning message */
+    PLOG_NOTE   = (1 << 2),/* Informational message */
+    PLOG_DEBUG  = (1 << 3),/* Debug message, displayed if verb >= 7 */
+
+    PLOG_ERRNO  = (1 << 8),/* Add error description to message */
+    PLOG_NOMUTE = (1 << 9), /* Mute setting does not apply for message */
+
+} openvpn_plugin_log_flags_t;
+
+
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+#define _ovpn_chk_fmt(a, b) __attribute__ ((format(gnu_printf, (a), (b))))
+#else
+#define _ovpn_chk_fmt(a, b) __attribute__ ((format(__printf__, (a), (b))))
+#endif
+#else  /* ifdef __GNUC__ */
+#define _ovpn_chk_fmt(a, b)
+#endif
+
+typedef void (*plugin_log_t)(openvpn_plugin_log_flags_t flags,
+                             const char *plugin_name,
+                             const char *format, ...) _ovpn_chk_fmt (3, 4);
+
+typedef void (*plugin_vlog_t)(openvpn_plugin_log_flags_t flags,
+                              const char *plugin_name,
+                              const char *format,
+                              va_list arglist) _ovpn_chk_fmt (3, 0);
+#undef _ovpn_chk_fmt
+
+/**
+ *  Export of secure_memzero() to be used inside plug-ins
+ *
+ *  @param data   Pointer to data to zeroise
+ *  @param len    Length of data, in bytes
+ *
+ */
+typedef void (*plugin_secure_memzero_t)(void *data, size_t len);
+
+/**
+ *  Export of openvpn_base64_encode() to be used inside plug-ins
+ *
+ *  @param data   Pointer to data to BASE64 encode
+ *  @param size   Length of data, in bytes
+ *  @param *str   Pointer to the return buffer.  This needed memory is
+ *                allocated by openvpn_base64_encode() and needs to be free()d
+ *                after use.
+ *
+ *  @return int   Returns the length of the buffer created, or -1 on error.
+ *
+ */
+typedef int (*plugin_base64_encode_t)(const void *data, int size, char **str);
+
+/**
+ *  Export of openvpn_base64_decode() to be used inside plug-ins
+ *
+ *  @param str    Pointer to the BASE64 encoded data
+ *  @param data   Pointer to the buffer where save the decoded data
+ *  @param size   Size of the destination buffer
+ *
+ *  @return int   Returns the length of the decoded data, or -1 on error or
+ *                if the destination buffer is too small.
+ *
+ */
+typedef int (*plugin_base64_decode_t)(const char *str, void *data, int size);
+
+
+/**
+ * Used by the openvpn_plugin_open_v3() function to pass callback
+ * function pointers to the plug-in.
+ *
+ * plugin_log
+ * plugin_vlog : Use these functions to add information to the OpenVPN log file.
+ *               Messages will only be displayed if the plugin_name parameter
+ *               is set. PLOG_DEBUG messages will only be displayed with plug-in
+ *               debug log verbosity (at the time of writing that's verb >= 7).
+ *
+ * plugin_secure_memzero
+ *             : Use this function to securely wipe sensitive information from
+ *               memory.  This function is declared in a way that the compiler
+ *               will not remove these function calls during the compiler
+ *               optimization phase.
+ */
+struct openvpn_plugin_callbacks
+{
+    plugin_log_t plugin_log;
+    plugin_vlog_t plugin_vlog;
+    plugin_secure_memzero_t plugin_secure_memzero;
+    plugin_base64_encode_t plugin_base64_encode;
+    plugin_base64_decode_t plugin_base64_decode;
+};
+
+/**
+ * Used by the openvpn_plugin_open_v3() function to indicate to the
+ * plug-in what kind of SSL implementation OpenVPN uses.  This is
+ * to avoid SEGV issues when OpenVPN is complied against mbed TLS
+ * and the plug-in against OpenSSL.
+ */
+typedef enum {
+    SSLAPI_NONE,
+    SSLAPI_OPENSSL,
+    SSLAPI_MBEDTLS
+} ovpnSSLAPI;
+
+/**
+ * Arguments used to transport variables to the plug-in.
+ * The struct openvpn_plugin_args_open_in is only used
+ * by the openvpn_plugin_open_v3() function.
+ *
+ * STRUCT MEMBERS
+ *
+ * type_mask : Set by OpenVPN to the logical OR of all script
+ *             types which this version of OpenVPN supports.
+ *
+ * argv : a NULL-terminated array of options provided to the OpenVPN
+ *        "plug-in" directive.  argv[0] is the dynamic library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * callbacks : a pointer to the plug-in callback function struct.
+ *
+ */
+struct openvpn_plugin_args_open_in
+{
+    const int type_mask;
+    const char **const argv;
+    const char **const envp;
+    struct openvpn_plugin_callbacks *callbacks;
+    const ovpnSSLAPI ssl_api;
+    const char *ovpn_version;
+    const unsigned int ovpn_version_major;
+    const unsigned int ovpn_version_minor;
+    const char *const ovpn_version_patch;
+};
+
+
+/**
+ * Arguments used to transport variables from the plug-in back
+ * to the OpenVPN process.  The struct openvpn_plugin_args_open_return
+ * is only used by the openvpn_plugin_open_v3() function.
+ *
+ * STRUCT MEMBERS
+ *
+ * type_mask  : The plug-in should set this value to the logical OR of all script
+ *              types which the plug-in wants to intercept.  For example, if the
+ *              script wants to intercept the client-connect and client-disconnect
+ *              script types:
+ *
+ *              type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT)
+ *                         | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT)
+ *
+ * handle :     Pointer to a global plug-in context, created by the plug-in.  This pointer
+ *              is passed on to the other plug-in calls.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ */
+struct openvpn_plugin_args_open_return
+{
+    int type_mask;
+    openvpn_plugin_handle_t handle;
+    struct openvpn_plugin_string_list **return_list;
+};
+
+/**
+ * Arguments used to transport variables to and from the
+ * plug-in.  The struct openvpn_plugin_args_func is only used
+ * by the openvpn_plugin_func_v3() function.
+ *
+ * STRUCT MEMBERS:
+ *
+ * type : one of the PLUGIN_x types.
+ *
+ * argv : a NULL-terminated array of "command line" options which
+ *        would normally be passed to the script.  argv[0] is the dynamic
+ *        library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * handle : Pointer to a global plug-in context, created by the plug-in's openvpn_plugin_open_v3().
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ *
+ * current_cert_depth : Certificate depth of the certificate being passed over (only if compiled with ENABLE_CRYPTO defined)
+ *
+ * *current_cert : X509 Certificate object received from the client (only if compiled with ENABLE_CRYPTO defined)
+ *
+ */
+struct openvpn_plugin_args_func_in
+{
+    const int type;
+    const char **const argv;
+    const char **const envp;
+    openvpn_plugin_handle_t handle;
+    void *per_client_context;
+#ifdef ENABLE_CRYPTO
+    int current_cert_depth;
+    openvpn_x509_cert_t *current_cert;
+#else
+    int __current_cert_depth_disabled; /* Unused, for compatibility purposes only */
+    void *__current_cert_disabled; /* Unused, for compatibility purposes only */
+#endif
+};
+
+
+/**
+ * Arguments used to transport variables to and from the
+ * plug-in.  The struct openvpn_plugin_args_func is only used
+ * by the openvpn_plugin_func_v3() function.
+ *
+ * STRUCT MEMBERS:
+ *
+ * return_list : used to return data back to OpenVPN for further processing/usage by
+ *               the OpenVPN executable.
+ *
+ */
+struct openvpn_plugin_args_func_return
+{
+    struct openvpn_plugin_string_list **return_list;
+};
+
+/*
+ * Multiple plugin modules can be cascaded, and modules can be
+ * used in tandem with scripts.  The order of operation is that
+ * the module func() functions are called in the order that
+ * the modules were specified in the config file.  If a script
+ * was specified as well, it will be called last.  If the
+ * return code of the module/script controls an authentication
+ * function (such as tls-verify or auth-user-pass-verify), then
+ * every module and script must return success (0) in order for
+ * the connection to be authenticated.
+ *
+ * Notes:
+ *
+ * Plugins which use a privilege-separation model (by forking in
+ * their initialization function before the main OpenVPN process
+ * downgrades root privileges and/or executes a chroot) must
+ * daemonize after a fork if the "daemon" environmental variable is
+ * set.  In addition, if the "daemon_log_redirect" variable is set,
+ * the plugin should preserve stdout/stderr across the daemon()
+ * syscall.  See the daemonize() function in plugin/auth-pam/auth-pam.c
+ * for an example.
+ */
+
+/*
+ * Prototypes for functions which OpenVPN plug-ins must define.
+ */
+
+/*
+ * FUNCTION: openvpn_plugin_open_v2
+ *
+ * REQUIRED: YES
+ *
+ * Called on initial plug-in load.  OpenVPN will preserve plug-in state
+ * across SIGUSR1 restarts but not across SIGHUP restarts.  A SIGHUP reset
+ * will cause the plugin to be closed and reopened.
+ *
+ * ARGUMENTS
+ *
+ * *type_mask : Set by OpenVPN to the logical OR of all script
+ *              types which this version of OpenVPN supports.  The plug-in
+ *              should set this value to the logical OR of all script types
+ *              which the plug-in wants to intercept.  For example, if the
+ *              script wants to intercept the client-connect and
+ *              client-disconnect script types:
+ *
+ *              *type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT)
+ *                         | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT)
+ *
+ * argv : a NULL-terminated array of options provided to the OpenVPN
+ *        "plug-in" directive.  argv[0] is the dynamic library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * An openvpn_plugin_handle_t value on success, NULL on failure
+ */
+OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v2)
+    (unsigned int *type_mask,
+    const char *argv[],
+    const char *envp[],
+    struct openvpn_plugin_string_list **return_list);
+
+/*
+ * FUNCTION: openvpn_plugin_func_v2
+ *
+ * Called to perform the work of a given script type.
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * type : one of the PLUGIN_x types
+ *
+ * argv : a NULL-terminated array of "command line" options which
+ *        would normally be passed to the script.  argv[0] is the dynamic
+ *        library pathname.
+ *
+ * envp : a NULL-terminated array of OpenVPN-set environmental
+ *        variables in "name=value" format.  Note that for security reasons,
+ *        these variables are not actually written to the "official"
+ *        environmental variable store of the process.
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ *
+ * In addition, OPENVPN_PLUGIN_FUNC_DEFERRED may be returned by
+ * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY.  This enables asynchronous
+ * authentication where the plugin (or one of its agents) may indicate
+ * authentication success/failure some number of seconds after the return
+ * of the OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY handler by writing a single
+ * char to the file named by auth_control_file in the environmental variable
+ * list (envp).
+ *
+ * first char of auth_control_file:
+ * '0' -- indicates auth failure
+ * '1' -- indicates auth success
+ *
+ * OpenVPN will delete the auth_control_file after it goes out of scope.
+ *
+ * If an OPENVPN_PLUGIN_ENABLE_PF handler is defined and returns success
+ * for a particular client instance, packet filtering will be enabled for that
+ * instance.  OpenVPN will then attempt to read the packet filter configuration
+ * from the temporary file named by the environmental variable pf_file.  This
+ * file may be generated asynchronously and may be dynamically updated during the
+ * client session, however the client will be blocked from sending or receiving
+ * VPN tunnel packets until the packet filter file has been generated.  OpenVPN
+ * will periodically test the packet filter file over the life of the client
+ * instance and reload when modified.  OpenVPN will delete the packet filter file
+ * when the client instance goes out of scope.
+ *
+ * Packet filter file grammar:
+ *
+ * [CLIENTS DROP|ACCEPT]
+ * {+|-}common_name1
+ * {+|-}common_name2
+ * . . .
+ * [SUBNETS DROP|ACCEPT]
+ * {+|-}subnet1
+ * {+|-}subnet2
+ * . . .
+ * [END]
+ *
+ * Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS
+ *
+ * CLIENTS refers to the set of clients (by their common-name) which
+ * this instance is allowed ('+') to connect to, or is excluded ('-')
+ * from connecting to.  Note that in the case of client-to-client
+ * connections, such communication must be allowed by the packet filter
+ * configuration files of both clients.
+ *
+ * SUBNETS refers to IP addresses or IP address subnets which this
+ * instance may connect to ('+') or is excluded ('-') from connecting
+ * to.
+ *
+ * DROP or ACCEPT defines default policy when there is no explicit match
+ * for a common-name or subnet.  The [END] tag must exist.  A special
+ * purpose tag called [KILL] will immediately kill the client instance.
+ * A given client or subnet rule applies to both incoming and outgoing
+ * packets.
+ *
+ * See plugin/defer/simple.c for an example on using asynchronous
+ * authentication and client-specific packet filtering.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v2)
+    (openvpn_plugin_handle_t handle,
+    const int type,
+    const char *argv[],
+    const char *envp[],
+    void *per_client_context,
+    struct openvpn_plugin_string_list **return_list);
+
+
+/*
+ * FUNCTION: openvpn_plugin_open_v3
+ *
+ * REQUIRED: YES
+ *
+ * Called on initial plug-in load.  OpenVPN will preserve plug-in state
+ * across SIGUSR1 restarts but not across SIGHUP restarts.  A SIGHUP reset
+ * will cause the plugin to be closed and reopened.
+ *
+ * ARGUMENTS
+ *
+ * version : fixed value, defines the API version of the OpenVPN plug-in API.  The plug-in
+ *           should validate that this value is matching the OPENVPN_PLUGINv3_STRUCTVER
+ *           value.
+ *
+ * arguments : Structure with all arguments available to the plug-in.
+ *
+ * retptr :    used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v3)
+    (const int version,
+    struct openvpn_plugin_args_open_in const *arguments,
+    struct openvpn_plugin_args_open_return *retptr);
+
+/*
+ * FUNCTION: openvpn_plugin_func_v3
+ *
+ * Called to perform the work of a given script type.
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * version : fixed value, defines the API version of the OpenVPN plug-in API.  The plug-in
+ *           should validate that this value is matching the OPENVPN_PLUGIN_VERSION value.
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * return_list : used to return data back to OpenVPN.
+ *
+ * RETURN VALUE
+ *
+ * OPENVPN_PLUGIN_FUNC_SUCCESS on success, OPENVPN_PLUGIN_FUNC_ERROR on failure
+ *
+ * In addition, OPENVPN_PLUGIN_FUNC_DEFERRED may be returned by
+ * OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY.  This enables asynchronous
+ * authentication where the plugin (or one of its agents) may indicate
+ * authentication success/failure some number of seconds after the return
+ * of the OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY handler by writing a single
+ * char to the file named by auth_control_file in the environmental variable
+ * list (envp).
+ *
+ * first char of auth_control_file:
+ * '0' -- indicates auth failure
+ * '1' -- indicates auth success
+ *
+ * OpenVPN will delete the auth_control_file after it goes out of scope.
+ *
+ * If an OPENVPN_PLUGIN_ENABLE_PF handler is defined and returns success
+ * for a particular client instance, packet filtering will be enabled for that
+ * instance.  OpenVPN will then attempt to read the packet filter configuration
+ * from the temporary file named by the environmental variable pf_file.  This
+ * file may be generated asynchronously and may be dynamically updated during the
+ * client session, however the client will be blocked from sending or receiving
+ * VPN tunnel packets until the packet filter file has been generated.  OpenVPN
+ * will periodically test the packet filter file over the life of the client
+ * instance and reload when modified.  OpenVPN will delete the packet filter file
+ * when the client instance goes out of scope.
+ *
+ * Packet filter file grammar:
+ *
+ * [CLIENTS DROP|ACCEPT]
+ * {+|-}common_name1
+ * {+|-}common_name2
+ * . . .
+ * [SUBNETS DROP|ACCEPT]
+ * {+|-}subnet1
+ * {+|-}subnet2
+ * . . .
+ * [END]
+ *
+ * Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS
+ *
+ * CLIENTS refers to the set of clients (by their common-name) which
+ * this instance is allowed ('+') to connect to, or is excluded ('-')
+ * from connecting to.  Note that in the case of client-to-client
+ * connections, such communication must be allowed by the packet filter
+ * configuration files of both clients.
+ *
+ * SUBNETS refers to IP addresses or IP address subnets which this
+ * instance may connect to ('+') or is excluded ('-') from connecting
+ * to.
+ *
+ * DROP or ACCEPT defines default policy when there is no explicit match
+ * for a common-name or subnet.  The [END] tag must exist.  A special
+ * purpose tag called [KILL] will immediately kill the client instance.
+ * A given client or subnet rule applies to both incoming and outgoing
+ * packets.
+ *
+ * See plugin/defer/simple.c for an example on using asynchronous
+ * authentication and client-specific packet filtering.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v3)
+    (const int version,
+    struct openvpn_plugin_args_func_in const *arguments,
+    struct openvpn_plugin_args_func_return *retptr);
+
+/*
+ * FUNCTION: openvpn_plugin_close_v1
+ *
+ * REQUIRED: YES
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * Called immediately prior to plug-in unload.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_close_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_abort_v1
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * Called when OpenVPN is in the process of aborting due to a fatal error.
+ * Will only be called on an open context returned by a prior successful
+ * openvpn_plugin_open callback.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_abort_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_client_constructor_v1
+ *
+ * Called to allocate a per-client memory region, which
+ * is then passed to the openvpn_plugin_func_v2 function.
+ * This function is called every time the OpenVPN server
+ * constructs a client instance object, which normally
+ * occurs when a session-initiating packet is received
+ * by a new client, even before the client has authenticated.
+ *
+ * This function should allocate the private memory needed
+ * by the plugin to track individual OpenVPN clients, and
+ * return a void * to this memory region.
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * RETURN VALUE
+ *
+ * void * pointer to plugin's private per-client memory region, or NULL
+ * if no memory region is required.
+ */
+OPENVPN_PLUGIN_DEF void *OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_constructor_v1)
+    (openvpn_plugin_handle_t handle);
+
+/*
+ * FUNCTION: openvpn_plugin_client_destructor_v1
+ *
+ * This function is called on client instance object destruction.
+ *
+ * REQUIRED: NO
+ *
+ * ARGUMENTS
+ *
+ * handle : the openvpn_plugin_handle_t value which was returned by
+ *          openvpn_plugin_open.
+ *
+ * per_client_context : the per-client context pointer which was returned by
+ *        openvpn_plugin_client_constructor_v1, if defined.
+ */
+OPENVPN_PLUGIN_DEF void OPENVPN_PLUGIN_FUNC(openvpn_plugin_client_destructor_v1)
+    (openvpn_plugin_handle_t handle, void *per_client_context);
+
+/*
+ * FUNCTION: openvpn_plugin_select_initialization_point_v1
+ *
+ * Several different points exist in OpenVPN's initialization sequence where
+ * the openvpn_plugin_open function can be called.  While the default is
+ * OPENVPN_PLUGIN_INIT_PRE_DAEMON, this function can be used to select a
+ * different initialization point.  For example, if your plugin needs to
+ * return configuration parameters to OpenVPN, use
+ * OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE.
+ *
+ * REQUIRED: NO
+ *
+ * RETURN VALUE:
+ *
+ * An OPENVPN_PLUGIN_INIT_x value.
+ */
+#define OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE 1
+#define OPENVPN_PLUGIN_INIT_PRE_DAEMON       2 /* default */
+#define OPENVPN_PLUGIN_INIT_POST_DAEMON      3
+#define OPENVPN_PLUGIN_INIT_POST_UID_CHANGE  4
+
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_select_initialization_point_v1)
+    (void);
+
+/*
+ * FUNCTION: openvpn_plugin_min_version_required_v1
+ *
+ * This function is called by OpenVPN to query the minimum
+ * plugin interface version number required by the plugin.
+ *
+ * REQUIRED: NO
+ *
+ * RETURN VALUE
+ *
+ * The minimum OpenVPN plugin interface version number necessary to support
+ * this plugin.
+ */
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_min_version_required_v1)
+    (void);
+
+/*
+ * Deprecated functions which are still supported for backward compatibility.
+ */
+
+OPENVPN_PLUGIN_DEF openvpn_plugin_handle_t OPENVPN_PLUGIN_FUNC(openvpn_plugin_open_v1)
+    (unsigned int *type_mask,
+    const char *argv[],
+    const char *envp[]);
+
+OPENVPN_PLUGIN_DEF int OPENVPN_PLUGIN_FUNC(openvpn_plugin_func_v1)
+    (openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[]);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OPENVPN_PLUGIN_H_ */
diff --git a/ltrc.inc b/ltrc.inc
new file mode 100644
index 0000000..701f200
--- /dev/null
+++ b/ltrc.inc
@@ -0,0 +1,23 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2008-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+# Required to build Windows resource file
+
+RCCOMPILE = $(RC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) \
+	$(AM_CPPFLAGS) $(CPPFLAGS)
+LTRCCOMPILE = $(LIBTOOL) --mode=compile --tag=RC $(RCCOMPILE)
+
+.rc.lo:
+	$(LTRCCOMPILE) -i "$<" -o "$@"
+
+.rc.o:
+	$(RCCOMPILE) -i "$<" -o "$@"
+
+.mc.rc:
+	$(WINDMC) "$<"
diff --git a/m4/ax_emptyarray.m4 b/m4/ax_emptyarray.m4
new file mode 100644
index 0000000..c6781c1
--- /dev/null
+++ b/m4/ax_emptyarray.m4
@@ -0,0 +1,40 @@
+dnl @synopsis AX_EMPTY_ARRAY
+dnl
+dnl Define EMPTY_ARRAY_SIZE to be either "0"
+dnl or "" depending on which syntax the compiler
+dnl prefers for empty arrays in structs.
+dnl
+dnl @version
+dnl @author James Yonan <jim@yonan.net>
+AC_DEFUN([AX_EMPTY_ARRAY], [
+	AS_VAR_PUSHDEF([VAR],[ax_cv_c_empty_array])dnl
+	AC_CACHE_CHECK(
+		[for C compiler empty array size],
+		[VAR],
+		[AC_COMPILE_IFELSE(
+			[AC_LANG_PROGRAM(
+				,
+				[[
+struct { int foo; int bar[0]; } mystruct;
+				]]
+			)],
+			[VAR=0],
+			[AC_COMPILE_IFELSE(
+				[AC_LANG_PROGRAM(
+					,
+					[[
+struct { int foo; int bar[]; } mystruct;
+					]]
+				)],
+				[VAR=],
+				[AC_MSG_ERROR([C compiler is unable to creaty empty arrays])]
+			)]
+		)]
+	)dnl
+	AC_DEFINE_UNQUOTED(
+		[EMPTY_ARRAY_SIZE],
+		[$VAR],
+		[Dimension to use for empty array declaration]
+	)dnl
+	AS_VAR_POPDEF([VAR])dnl
+])
diff --git a/m4/ax_socklen_t.m4 b/m4/ax_socklen_t.m4
new file mode 100644
index 0000000..b420a17
--- /dev/null
+++ b/m4/ax_socklen_t.m4
@@ -0,0 +1,65 @@
+dnl -- The following is base of curl's acinclude.m4 --
+dnl Check for socklen_t: historically on BSD it is an int, and in
+dnl POSIX 1g it is a type of its own, but some platforms use different
+dnl types for the argument to getsockopt, getpeername, etc.  So we
+dnl have to test to find something that will work.
+AC_DEFUN([AX_TYPE_SOCKLEN_T], [
+	AC_CHECK_TYPE(
+		[socklen_t],
+		,
+		[
+			AS_VAR_PUSHDEF([VAR],[ax_cv_socklen_t_equiv])dnl
+			AC_CACHE_CHECK(
+				[for socklen_t equivalent],
+				[VAR],
+				[
+					#AS_CASE is not supported on <autoconf-2.60
+					case "${host}" in
+					*-mingw*) VAR=int ;;
+					*)
+						# Systems have either "struct sockaddr *" or
+						# "void *" as the second argument to getpeername
+						for arg2 in "struct sockaddr" void; do
+							for t in int size_t unsigned long "unsigned long"; do
+								AC_COMPILE_IFELSE(
+									[AC_LANG_PROGRAM(
+										[[
+#include <sys/types.h>
+#include <sys/socket.h>
+int getpeername (int, $arg2 *, $t *);
+										]],
+										[[
+$t len;
+getpeername(0,0,&len);
+										]]
+									)],
+									[VAR="$t"; break]
+								)
+							done
+							test -n "$VAR" && break
+						done
+						;;
+					esac
+				]
+				AS_VAR_IF(
+					[VAR],
+					[],
+					[AC_MSG_ERROR([Cannot find a type to use in place of socklen_t])],
+					[AC_DEFINE_UNQUOTED(
+						[socklen_t],
+						[$VAR],
+						[type to use in place of socklen_t if not defined]
+					)]
+				)
+			)
+		],
+		[[
+#include <sys/types.h>
+#ifdef _WIN32
+#include <ws2tcpip.h>
+#else
+#include <sys/socket.h>
+#endif
+		]]
+	)
+])
diff --git a/m4/ax_varargs.m4 b/m4/ax_varargs.m4
new file mode 100644
index 0000000..c295d21
--- /dev/null
+++ b/m4/ax_varargs.m4
@@ -0,0 +1,77 @@
+dnl @synopsis AX_CPP_VARARG_MACRO_GCC
+dnl
+dnl Test if the preprocessor understands GNU GCC-style vararg macros.
+dnl If it does, defines HAVE_CPP_VARARG_MACRO_GCC to 1.
+dnl
+dnl @version
+dnl @author James Yonan <jim@yonan.net>, Matthias Andree <matthias.andree@web.de>
+AC_DEFUN([AX_CPP_VARARG_MACRO_GCC], [dnl
+	AS_VAR_PUSHDEF([VAR], [ax_cv_cpp_vararg_macro_gcc])dnl
+	AC_CACHE_CHECK(
+		[for GNU GCC vararg macro support],
+		[VAR],
+		[AC_COMPILE_IFELSE(
+			[AC_LANG_PROGRAM(
+				[[
+#define macro(a, b...) func(a, b)
+int func(int a, int b, int c);
+				]],
+				[[
+int i = macro(1, 2, 3);
+				]]
+			)],
+			[VAR=yes],
+			[VAR=no]
+		)]
+	)dnl
+
+	AS_VAR_IF(
+		[VAR],
+		[yes],
+		[AC_DEFINE(
+			[HAVE_CPP_VARARG_MACRO_GCC],
+			[1], 
+			[Define to 1 if your compiler supports GNU GCC-style variadic macros]
+		)]
+	)dnl
+	AS_VAR_POPDEF([VAR])dnl
+])
+
+dnl @synopsis AX_CPP_VARARG_MACRO_ISO
+dnl
+dnl Test if the preprocessor understands ISO C 1999 vararg macros.
+dnl If it does, defines HAVE_CPP_VARARG_MACRO_ISO to 1.
+dnl
+dnl @version
+dnl @author James Yonan <jim@yonan.net>, Matthias Andree <matthias.andree@web.de>
+AC_DEFUN([AX_CPP_VARARG_MACRO_ISO], [dnl
+	AS_VAR_PUSHDEF([VAR],[ax_cv_cpp_vararg_macro_iso])dnl
+	AC_CACHE_CHECK(
+		[for ISO C 1999 vararg macro support],
+		[VAR],
+		[AC_COMPILE_IFELSE(
+			[AC_LANG_PROGRAM(
+				[[
+#define macro(a, ...) func(a, __VA_ARGS__)
+int func(int a, int b, int c);
+				]],
+				[[
+int i = macro(1, 2, 3);
+				]]
+			)],
+			[VAR=yes],
+			[VAR=no]
+		)]
+	)dnl
+
+	AS_VAR_IF(
+		[VAR],
+		[yes],
+		[AC_DEFINE(
+			[HAVE_CPP_VARARG_MACRO_ISO],
+			[1], 
+			[Define to 1 if your compiler supports ISO C99 variadic macros]
+		)]
+	)dnl
+	AS_VAR_POPDEF([VAR])dnl
+])
diff --git a/m4/pkg.m4 b/m4/pkg.m4
new file mode 100644
index 0000000..12d2a58
--- /dev/null
+++ b/m4/pkg.m4
@@ -0,0 +1,159 @@
+# pkg.m4 - Macros to locate and utilise pkg-config.            -*- Autoconf -*-
+# serial 1 (pkg-config-0.24)
+# 
+# Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# As a special exception to the GNU General Public License, if you
+# distribute this file as part of a program that contains a
+# configuration script generated by Autoconf, you may include it under
+# the same distribution terms that you use for the rest of that program.
+
+# PKG_PROG_PKG_CONFIG([MIN-VERSION])
+# ----------------------------------
+AC_DEFUN([PKG_PROG_PKG_CONFIG],
+[m4_pattern_forbid([^_?PKG_[A-Z_]+$])
+m4_pattern_allow([^PKG_CONFIG(_(PATH|LIBDIR|SYSROOT_DIR|ALLOW_SYSTEM_(CFLAGS|LIBS)))?$])
+m4_pattern_allow([^PKG_CONFIG_(DISABLE_UNINSTALLED|TOP_BUILD_DIR|DEBUG_SPEW)$])
+AC_ARG_VAR([PKG_CONFIG], [path to pkg-config utility])
+AC_ARG_VAR([PKG_CONFIG_PATH], [directories to add to pkg-config's search path])
+AC_ARG_VAR([PKG_CONFIG_LIBDIR], [path overriding pkg-config's built-in search path])
+
+if test "x$ac_cv_env_PKG_CONFIG_set" != "xset"; then
+	AC_PATH_TOOL([PKG_CONFIG], [pkg-config])
+fi
+if test -n "$PKG_CONFIG"; then
+	_pkg_min_version=m4_default([$1], [0.9.0])
+	AC_MSG_CHECKING([pkg-config is at least version $_pkg_min_version])
+	if $PKG_CONFIG --atleast-pkgconfig-version $_pkg_min_version; then
+		AC_MSG_RESULT([yes])
+	else
+		AC_MSG_RESULT([no])
+		PKG_CONFIG=""
+	fi
+fi[]dnl
+])# PKG_PROG_PKG_CONFIG
+
+# PKG_CHECK_EXISTS(MODULES, [ACTION-IF-FOUND], [ACTION-IF-NOT-FOUND])
+#
+# Check to see whether a particular set of modules exists.  Similar
+# to PKG_CHECK_MODULES(), but does not set variables or print errors.
+#
+# Please remember that m4 expands AC_REQUIRE([PKG_PROG_PKG_CONFIG])
+# only at the first occurence in configure.ac, so if the first place
+# it's called might be skipped (such as if it is within an "if", you
+# have to call PKG_CHECK_EXISTS manually
+# --------------------------------------------------------------
+AC_DEFUN([PKG_CHECK_EXISTS],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])dnl
+if test -n "$PKG_CONFIG" && \
+    AC_RUN_LOG([$PKG_CONFIG --exists --print-errors "$1"]); then
+  m4_default([$2], [:])
+m4_ifvaln([$3], [else
+  $3])dnl
+fi])
+
+# _PKG_CONFIG([VARIABLE], [COMMAND], [MODULES])
+# ---------------------------------------------
+m4_define([_PKG_CONFIG],
+[if test -n "$$1"; then
+    pkg_cv_[]$1="$$1"
+ elif test -n "$PKG_CONFIG"; then
+    PKG_CHECK_EXISTS([$3],
+                     [pkg_cv_[]$1=`$PKG_CONFIG --[]$2 "$3" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes ],
+		     [pkg_failed=yes])
+ else
+    pkg_failed=untried
+fi[]dnl
+])# _PKG_CONFIG
+
+# _PKG_SHORT_ERRORS_SUPPORTED
+# -----------------------------
+AC_DEFUN([_PKG_SHORT_ERRORS_SUPPORTED],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi[]dnl
+])# _PKG_SHORT_ERRORS_SUPPORTED
+
+
+# PKG_CHECK_MODULES(VARIABLE-PREFIX, MODULES, [ACTION-IF-FOUND],
+# [ACTION-IF-NOT-FOUND])
+#
+#
+# Note that if there is a possibility the first call to
+# PKG_CHECK_MODULES might not happen, you should be sure to include an
+# explicit call to PKG_PROG_PKG_CONFIG in your configure.ac
+#
+#
+# --------------------------------------------------------------
+AC_DEFUN([PKG_CHECK_MODULES],
+[AC_REQUIRE([PKG_PROG_PKG_CONFIG])dnl
+AC_ARG_VAR([$1][_CFLAGS], [C compiler flags for $1, overriding pkg-config])dnl
+AC_ARG_VAR([$1][_LIBS], [linker flags for $1, overriding pkg-config])dnl
+
+pkg_failed=no
+AC_MSG_CHECKING([for $1])
+
+_PKG_CONFIG([$1][_CFLAGS], [cflags], [$2])
+_PKG_CONFIG([$1][_LIBS], [libs], [$2])
+
+m4_define([_PKG_TEXT], [Alternatively, you may set the environment variables $1[]_CFLAGS
+and $1[]_LIBS to avoid the need to call pkg-config.
+See the pkg-config man page for more details.])
+
+if test $pkg_failed = yes; then
+   	AC_MSG_RESULT([no])
+        _PKG_SHORT_ERRORS_SUPPORTED
+        if test $_pkg_short_errors_supported = yes; then
+	        $1[]_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "$2" 2>&1`
+        else 
+	        $1[]_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "$2" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$$1[]_PKG_ERRORS" >&AS_MESSAGE_LOG_FD
+
+	m4_default([$4], [AC_MSG_ERROR(
+[Package requirements ($2) were not met:
+
+$$1_PKG_ERRORS
+
+Consider adjusting the PKG_CONFIG_PATH environment variable if you
+installed software in a non-standard prefix.
+
+_PKG_TEXT])[]dnl
+        ])
+elif test $pkg_failed = untried; then
+     	AC_MSG_RESULT([no])
+	m4_default([$4], [AC_MSG_FAILURE(
+[The pkg-config script could not be found or is too old.  Make sure it
+is in your PATH or set the PKG_CONFIG environment variable to the full
+path to pkg-config.
+
+_PKG_TEXT
+
+To get pkg-config, see <http://pkg-config.freedesktop.org/>.])[]dnl
+        ])
+else
+	$1[]_CFLAGS=$pkg_cv_[]$1[]_CFLAGS
+	$1[]_LIBS=$pkg_cv_[]$1[]_LIBS
+        AC_MSG_RESULT([yes])
+	$3
+fi[]dnl
+])# PKG_CHECK_MODULES
diff --git a/patches/add_missing_licenses.patch b/patches/add_missing_licenses.patch
new file mode 100644
index 0000000..390ac29
--- /dev/null
+++ b/patches/add_missing_licenses.patch
@@ -0,0 +1,467 @@
+Index: openvpn/LICENSE
+===================================================================
+--- openvpn.orig/LICENSE
++++ openvpn/LICENSE
+@@ -566,3 +566,462 @@ Public License instead of this License.
+ 
+ 
+ END COPYRIGHT.GPL
++
++------------------
++
++BSD 3-Clause License:
++-----------------
++
++/*
++ * Redistribution and use in source and binary forms, with or without modifi-
++ * cation, are permitted provided that the following conditions are met:
++ *
++ *   o  Redistributions of source code must retain the above copyright notice,
++ *      this list of conditions and the following disclaimer.
++ *
++ *   o  Redistributions in binary form must reproduce the above copyright no-
++ *      tice, this list of conditions and the following disclaimer in the do-
++ *      cumentation and/or other materials provided with the distribution.
++ *
++ *   o  The names of the contributors may not be used to endorse or promote
++ *      products derived from this software without specific prior written
++ *      permission.
++ *
++ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
++ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
++ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
++ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LI-
++ * ABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUEN-
++ * TIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
++ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEV-
++ * ER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABI-
++ * LITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
++ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
++ */
++
++------------------
++src/compat/compat-lz4.c
++
++/*
++   LZ4 - Fast LZ compression algorithm
++   Copyright (C) 2011-present, Yann Collet.
++
++   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
++
++   Redistribution and use in source and binary forms, with or without
++   modification, are permitted provided that the following conditions are
++   met:
++
++       * Redistributions of source code must retain the above copyright
++   notice, this list of conditions and the following disclaimer.
++       * Redistributions in binary form must reproduce the above
++   copyright notice, this list of conditions and the following disclaimer
++   in the documentation and/or other materials provided with the
++   distribution.
++
++   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
++   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
++   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
++   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
++   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
++   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
++   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
++   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
++   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
++   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
++   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
++
++   You can contact the author at :
++    - LZ4 homepage : http://www.lz4.org
++    - LZ4 source repository : https://github.com/lz4/lz4
++*/
++
++------------------
++m4/pkg.m4
++
++# Copyright © 2004 Scott James Remnant <scott@netsplit.com>.
++#
++# This program is free software; you can redistribute it and/or modify
++# it under the terms of the GNU General Public License as published by
++# the Free Software Foundation; either version 2 of the License, or
++# (at your option) any later version.
++#
++# This program is distributed in the hope that it will be useful, but
++# WITHOUT ANY WARRANTY; without even the implied warranty of
++# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
++# General Public License for more details.
++#
++# You should have received a copy of the GNU General Public License along
++# with this program; if not, write to the Free Software Foundation, Inc.,
++# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
++#
++# As a special exception to the GNU General Public License, if you
++# distribute this file as part of a program that contains a
++# configuration script generated by Autoconf, you may include it under
++# the same distribution terms that you use for the rest of that program.
++
++       GNU General Public License v2.0 w/Autoconf exception
++                    GNU GENERAL PUBLIC LICENSE
++                       Version 2, June 1991
++
++ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
++ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
++ Everyone is permitted to copy and distribute verbatim copies
++ of this license document, but changing it is not allowed.
++
++                            Preamble
++
++  The licenses for most software are designed to take away your
++freedom to share and change it.  By contrast, the GNU General Public
++License is intended to guarantee your freedom to share and change free
++software--to make sure the software is free for all its users.  This
++General Public License applies to most of the Free Software
++Foundation's software and to any other program whose authors commit to
++using it.  (Some other Free Software Foundation software is covered by
++the GNU Lesser General Public License instead.)  You can apply it to
++your programs, too.
++
++  When we speak of free software, we are referring to freedom, not
++price.  Our General Public Licenses are designed to make sure that you
++have the freedom to distribute copies of free software (and charge for
++this service if you wish), that you receive source code or can get it
++if you want it, that you can change the software or use pieces of it
++in new free programs; and that you know you can do these things.
++
++  To protect your rights, we need to make restrictions that forbid
++anyone to deny you these rights or to ask you to surrender the rights.
++These restrictions translate to certain responsibilities for you if you
++distribute copies of the software, or if you modify it.
++
++  For example, if you distribute copies of such a program, whether
++gratis or for a fee, you must give the recipients all the rights that
++you have.  You must make sure that they, too, receive or can get the
++source code.  And you must show them these terms so they know their
++rights.
++
++  We protect your rights with two steps: (1) copyright the software, and
++(2) offer you this license which gives you legal permission to copy,
++distribute and/or modify the software.
++
++  Also, for each author's protection and ours, we want to make certain
++that everyone understands that there is no warranty for this free
++software.  If the software is modified by someone else and passed on, we
++want its recipients to know that what they have is not the original, so
++that any problems introduced by others will not reflect on the original
++authors' reputations.
++
++  Finally, any free program is threatened constantly by software
++patents.  We wish to avoid the danger that redistributors of a free
++program will individually obtain patent licenses, in effect making the
++program proprietary.  To prevent this, we have made it clear that any
++patent must be licensed for everyone's free use or not licensed at all.
++
++  The precise terms and conditions for copying, distribution and
++modification follow.
++
++                    GNU GENERAL PUBLIC LICENSE
++   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
++
++  0. This License applies to any program or other work which contains
++a notice placed by the copyright holder saying it may be distributed
++under the terms of this General Public License.  The "Program", below,
++refers to any such program or work, and a "work based on the Program"
++means either the Program or any derivative work under copyright law:
++that is to say, a work containing the Program or a portion of it,
++either verbatim or with modifications and/or translated into another
++language.  (Hereinafter, translation is included without limitation in
++the term "modification".)  Each licensee is addressed as "you".
++
++Activities other than copying, distribution and modification are not
++covered by this License; they are outside its scope.  The act of
++running the Program is not restricted, and the output from the Program
++is covered only if its contents constitute a work based on the
++Program (independent of having been made by running the Program).
++Whether that is true depends on what the Program does.
++
++  1. You may copy and distribute verbatim copies of the Program's
++source code as you receive it, in any medium, provided that you
++conspicuously and appropriately publish on each copy an appropriate
++copyright notice and disclaimer of warranty; keep intact all the
++notices that refer to this License and to the absence of any warranty;
++and give any other recipients of the Program a copy of this License
++along with the Program.
++
++You may charge a fee for the physical act of transferring a copy, and
++you may at your option offer warranty protection in exchange for a fee.
++
++  2. You may modify your copy or copies of the Program or any portion
++of it, thus forming a work based on the Program, and copy and
++distribute such modifications or work under the terms of Section 1
++above, provided that you also meet all of these conditions:
++
++    a) You must cause the modified files to carry prominent notices
++    stating that you changed the files and the date of any change.
++
++    b) You must cause any work that you distribute or publish, that in
++    whole or in part contains or is derived from the Program or any
++    part thereof, to be licensed as a whole at no charge to all third
++    parties under the terms of this License.
++
++    c) If the modified program normally reads commands interactively
++    when run, you must cause it, when started running for such
++    interactive use in the most ordinary way, to print or display an
++    announcement including an appropriate copyright notice and a
++    notice that there is no warranty (or else, saying that you provide
++    a warranty) and that users may redistribute the program under
++    these conditions, and telling the user how to view a copy of this
++    License.  (Exception: if the Program itself is interactive but
++    does not normally print such an announcement, your work based on
++    the Program is not required to print an announcement.)
++
++These requirements apply to the modified work as a whole.  If
++identifiable sections of that work are not derived from the Program,
++and can be reasonably considered independent and separate works in
++themselves, then this License, and its terms, do not apply to those
++sections when you distribute them as separate works.  But when you
++distribute the same sections as part of a whole which is a work based
++on the Program, the distribution of the whole must be on the terms of
++this License, whose permissions for other licensees extend to the
++entire whole, and thus to each and every part regardless of who wrote it.
++
++Thus, it is not the intent of this section to claim rights or contest
++your rights to work written entirely by you; rather, the intent is to
++exercise the right to control the distribution of derivative or
++collective works based on the Program.
++
++In addition, mere aggregation of another work not based on the Program
++with the Program (or with a work based on the Program) on a volume of
++a storage or distribution medium does not bring the other work under
++the scope of this License.
++
++  3. You may copy and distribute the Program (or a work based on it,
++under Section 2) in object code or executable form under the terms of
++Sections 1 and 2 above provided that you also do one of the following:
++
++    a) Accompany it with the complete corresponding machine-readable
++    source code, which must be distributed under the terms of Sections
++    1 and 2 above on a medium customarily used for software interchange; or,
++
++    b) Accompany it with a written offer, valid for at least three
++    years, to give any third party, for a charge no more than your
++    cost of physically performing source distribution, a complete
++    machine-readable copy of the corresponding source code, to be
++    distributed under the terms of Sections 1 and 2 above on a medium
++    customarily used for software interchange; or,
++
++    c) Accompany it with the information you received as to the offer
++    to distribute corresponding source code.  (This alternative is
++    allowed only for noncommercial distribution and only if you
++    received the program in object code or executable form with such
++    an offer, in accord with Subsection b above.)
++
++The source code for a work means the preferred form of the work for
++making modifications to it.  For an executable work, complete source
++code means all the source code for all modules it contains, plus any
++associated interface definition files, plus the scripts used to
++control compilation and installation of the executable.  However, as a
++special exception, the source code distributed need not include
++anything that is normally distributed (in either source or binary
++form) with the major components (compiler, kernel, and so on) of the
++operating system on which the executable runs, unless that component
++itself accompanies the executable.
++
++If distribution of executable or object code is made by offering
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++access to copy the source code from the same place counts as
++distribution of the source code, even though third parties are not
++compelled to copy the source along with the object code.
++
++  4. You may not copy, modify, sublicense, or distribute the Program
++except as expressly provided under this License.  Any attempt
++otherwise to copy, modify, sublicense or distribute the Program is
++void, and will automatically terminate your rights under this License.
++However, parties who have received copies, or rights, from you under
++this License will not have their licenses terminated so long as such
++parties remain in full compliance.
++
++  5. You are not required to accept this License, since you have not
++signed it.  However, nothing else grants you permission to modify or
++distribute the Program or its derivative works.  These actions are
++prohibited by law if you do not accept this License.  Therefore, by
++modifying or distributing the Program (or any work based on the
++Program), you indicate your acceptance of this License to do so, and
++all its terms and conditions for copying, distributing or modifying
++the Program or works based on it.
++
++  6. Each time you redistribute the Program (or any work based on the
++Program), the recipient automatically receives a license from the
++original licensor to copy, distribute or modify the Program subject to
++these terms and conditions.  You may not impose any further
++restrictions on the recipients' exercise of the rights granted herein.
++You are not responsible for enforcing compliance by third parties to
++this License.
++
++  7. If, as a consequence of a court judgment or allegation of patent
++infringement or for any other reason (not limited to patent issues),
++conditions are imposed on you (whether by court order, agreement or
++otherwise) that contradict the conditions of this License, they do not
++excuse you from the conditions of this License.  If you cannot
++distribute so as to satisfy simultaneously your obligations under this
++License and any other pertinent obligations, then as a consequence you
++may not distribute the Program at all.  For example, if a patent
++license would not permit royalty-free redistribution of the Program by
++all those who receive copies directly or indirectly through you, then
++the only way you could satisfy both it and this License would be to
++refrain entirely from distribution of the Program.
++
++If any portion of this section is held invalid or unenforceable under
++any particular circumstance, the balance of the section is intended to
++apply and the section as a whole is intended to apply in other
++circumstances.
++
++It is not the purpose of this section to induce you to infringe any
++patents or other property right claims or to contest validity of any
++such claims; this section has the sole purpose of protecting the
++integrity of the free software distribution system, which is
++implemented by public license practices.  Many people have made
++generous contributions to the wide range of software distributed
++through that system in reliance on consistent application of that
++system; it is up to the author/donor to decide if he or she is willing
++to distribute software through any other system and a licensee cannot
++impose that choice.
++
++This section is intended to make thoroughly clear what is believed to
++be a consequence of the rest of this License.
++
++  8. If the distribution and/or use of the Program is restricted in
++certain countries either by patents or by copyrighted interfaces, the
++original copyright holder who places the Program under this License
++may add an explicit geographical distribution limitation excluding
++those countries, so that distribution is permitted only in or among
++countries not thus excluded.  In such case, this License incorporates
++the limitation as if written in the body of this License.
++
++  9. The Free Software Foundation may publish revised and/or new versions
++of the General Public License from time to time.  Such new versions will
++be similar in spirit to the present version, but may differ in detail to
++address new problems or concerns.
++
++Each version is given a distinguishing version number.  If the Program
++specifies a version number of this License which applies to it and "any
++later version", you have the option of following the terms and conditions
++either of that version or of any later version published by the Free
++Software Foundation.  If the Program does not specify a version number of
++this License, you may choose any version ever published by the Free Software
++Foundation.
++
++  10. If you wish to incorporate parts of the Program into other free
++programs whose distribution conditions are different, write to the author
++to ask for permission.  For software which is copyrighted by the Free
++Software Foundation, write to the Free Software Foundation; we sometimes
++make exceptions for this.  Our decision will be guided by the two goals
++of preserving the free status of all derivatives of our free software and
++of promoting the sharing and reuse of software generally.
++
++                            NO WARRANTY
++
++  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
++FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
++OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
++PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
++OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
++MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
++TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
++PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
++REPAIR OR CORRECTION.
++
++  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
++WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
++REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
++INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
++OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
++TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
++YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
++PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
++POSSIBILITY OF SUCH DAMAGES.
++
++                     END OF TERMS AND CONDITIONS
++
++            How to Apply These Terms to Your New Programs
++
++  If you develop a new program, and you want it to be of the greatest
++possible use to the public, the best way to achieve this is to make it
++free software which everyone can redistribute and change under these terms.
++
++  To do so, attach the following notices to the program.  It is safest
++to attach them to the start of each source file to most effectively
++convey the exclusion of warranty; and each file should have at least
++the "copyright" line and a pointer to where the full notice is found.
++
++    <one line to give the program's name and a brief idea of what it does.>
++    Copyright (C) <year>  <name of author>
++
++    This program is free software; you can redistribute it and/or modify
++    it under the terms of the GNU General Public License version 2
++    as published by the Free Software Foundation.
++
++    This program is distributed in the hope that it will be useful,
++    but WITHOUT ANY WARRANTY; without even the implied warranty of
++    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
++    GNU General Public License for more details.
++
++    You should have received a copy of the GNU General Public License along
++    with this program; if not, write to the Free Software Foundation, Inc.,
++    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
++
++Also add information on how to contact you by electronic and paper mail.
++
++If the program is interactive, make it output a short notice like this
++when it starts in an interactive mode:
++
++    Gnomovision version 69, Copyright (C) year name of author
++    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
++    This is free software, and you are welcome to redistribute it
++    under certain conditions; type `show c' for details.
++
++The hypothetical commands `show w' and `show c' should show the appropriate
++parts of the General Public License.  Of course, the commands you use may
++be called something other than `show w' and `show c'; they could even be
++mouse-clicks or menu items--whatever suits your program.
++
++You should also get your employer (if you work as a programmer) or your
++school, if any, to sign a "copyright disclaimer" for the program, if
++necessary.  Here is a sample; alter the names:
++
++  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
++  `Gnomovision' (which makes passes at compilers) written by James Hacker.
++
++  <signature of Ty Coon>, 1 April 1989
++  Ty Coon, President of Vice
++
++This General Public License does not permit incorporating your program into
++proprietary programs.  If your program is a subroutine library, you may
++consider it more useful to permit linking proprietary applications with the
++library.  If this is what you want to do, use the GNU Lesser General
++Public License instead of this License.
++
++Autoconf Exception
++
++As a special exception, the Free Software Foundation gives unlimited permission
++to copy, distribute and modify the configure scripts that are the output of
++Autoconf. You need not follow the terms of the GNU General Public License
++when using or distributing such scripts, even though portions of the text
++of Autoconf appear in them. The GNU General Public License (GPL) does govern
++all other use of the material that constitutes the Autoconf program.
++
++Certain portions of the Autoconf source text are designed to be copied (in
++certain cases, depending on the input) into the output of Autoconf. We call
++these the "data" portions. The rest of the Autoconf source text consists of
++comments plus executable code that decides which of the data portions to output
++in any given case. We call these comments and executable code the "non-data"
++portions. Autoconf never copies any of the non-data portions into its output.
++
++This special exception to the GPL applies to versions of Autoconf released
++by the Free Software Foundation. When you make and distribute a modified version
++of Autoconf, you may extend this special exception to the GPL to apply to
++your modified version as well, *unless* your modified version has the potential
++to copy into its output some of the text that was the non-data portion of
++the version that you started with. (In other words, unless your change moves
++or copies text from the non-data portions to the data portions.) If your modification
++has such potential, you must delete any notice of this special exception to
++the GPL from your modified version.
diff --git a/patches/cleanup_makefiles.patch b/patches/cleanup_makefiles.patch
new file mode 100644
index 0000000..33c3a3b
--- /dev/null
+++ b/patches/cleanup_makefiles.patch
@@ -0,0 +1,112 @@
+Index: openvpn/configure.ac
+===================================================================
+--- openvpn.orig/configure.ac
++++ openvpn/configure.ac
+@@ -1312,10 +1312,6 @@ if test "${enable_werror}" = "yes"; then
+ 	CFLAGS="${CFLAGS} -Werror"
+ fi
+ 
+-if test "${WIN32}" = "yes"; then
+-	test -z "${MAN2HTML}" && AC_MSG_ERROR([man2html is required for win32])
+-fi
+-
+ if test "${enable_plugin_auth_pam}" = "yes"; then
+ 	PLUGIN_AUTH_PAM_CFLAGS="${LIBPAM_CFLAGS}"
+ 	if test "${enable_pam_dlopen}" = "yes"; then
+@@ -1418,28 +1414,11 @@ fi
+ AC_CONFIG_FILES([
+ 	version.sh
+ 	Makefile
+-	build/Makefile
+-	build/msvc/Makefile
+-	build/msvc/msvc-generate/Makefile
+-	distro/Makefile
+-	distro/systemd/Makefile
+ 	include/Makefile
+ 	src/Makefile
+ 	src/compat/Makefile
+ 	src/openvpn/Makefile
+-	src/openvpnserv/Makefile
+ 	src/plugins/Makefile
+-	src/plugins/auth-pam/Makefile
+ 	src/plugins/down-root/Makefile
+-	tests/Makefile
+-        tests/unit_tests/Makefile
+-        tests/unit_tests/example_test/Makefile
+-        tests/unit_tests/openvpn/Makefile
+-        tests/unit_tests/plugins/Makefile
+-        tests/unit_tests/plugins/auth-pam/Makefile
+-        vendor/Makefile
+-	sample/Makefile
+-	doc/Makefile
+ ])
+-AC_CONFIG_FILES([tests/t_client.sh], [chmod +x tests/t_client.sh])
+ AC_OUTPUT
+Index: openvpn/src/Makefile.am
+===================================================================
+--- openvpn.orig/src/Makefile.am
++++ openvpn/src/Makefile.am
+@@ -12,4 +12,4 @@
+ MAINTAINERCLEANFILES = \
+ 	$(srcdir)/Makefile.in
+ 
+-SUBDIRS = compat openvpn openvpnserv plugins
++SUBDIRS = compat openvpn plugins
+Index: openvpn/src/openvpn/Makefile.am
+===================================================================
+--- openvpn.orig/src/openvpn/Makefile.am
++++ openvpn/src/openvpn/Makefile.am
+@@ -9,7 +9,7 @@
+ #  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+ #
+ 
+-include $(top_srcdir)/build/ltrc.inc
++include $(top_srcdir)/ltrc.inc
+ 
+ MAINTAINERCLEANFILES = \
+ 	$(srcdir)/Makefile.in
+Index: openvpn/src/plugins/Makefile.am
+===================================================================
+--- openvpn.orig/src/plugins/Makefile.am
++++ openvpn/src/plugins/Makefile.am
+@@ -12,4 +12,4 @@
+ MAINTAINERCLEANFILES = \
+ 	$(srcdir)/Makefile.in
+ 
+-SUBDIRS = auth-pam down-root
++SUBDIRS = down-root
+Index: openvpn/Makefile.am
+===================================================================
+--- openvpn.orig/Makefile.am
++++ openvpn/Makefile.am
+@@ -53,26 +53,14 @@ BUILT_SOURCES = \
+ 	config-version.h
+ endif
+ 
+-SUBDIRS = build distro include src sample doc vendor tests
++SUBDIRS = include src
+ 
+ dist_doc_DATA = \
+-	README \
+-	README.IPv6 \
+-	README.mbedtls \
+-	Changes.rst \
+-	COPYRIGHT.GPL \
+-	COPYING
++	README.IPv6
++	LICENSE
+ 
+ dist_noinst_DATA = \
+-	.gitignore \
+-	.gitattributes \
+-	PORTS \
+-	README.IPv6 TODO.IPv6 \
+-	README.mbedtls \
+-	openvpn.sln \
+-	msvc-env.bat \
+-	msvc-dev.bat \
+-	msvc-build.bat
++	README.IPv6
+ 
+ dist_noinst_HEADERS = \
+ 	config-msvc.h \
diff --git a/patches/fix_long_password.patch b/patches/fix_long_password.patch
new file mode 100644
index 0000000..b731dac
--- /dev/null
+++ b/patches/fix_long_password.patch
@@ -0,0 +1,18 @@
+Index: openvpn/src/openvpn/options.c
+===================================================================
+--- openvpn.orig/src/openvpn/options.c
++++ openvpn/src/openvpn/options.c
+@@ -4243,7 +4243,12 @@ parse_line(const char *line,
+     bool backslash = false;
+     char in, out;
+ 
+-    char parm[OPTION_PARM_SIZE];
++#ifdef ENABLE_PKCS11
++#   define PARM_SIZE USER_PASS_LEN
++#else
++#   define PARM_SIZE OPTION_PARM_SIZE
++#endif
++    char parm[PARM_SIZE];
+     unsigned int parm_len = 0;
+ 
+     msglevel &= ~M_OPTERR;
diff --git a/patches/remove_autoconf_vars.patch b/patches/remove_autoconf_vars.patch
new file mode 100644
index 0000000..50e9ea6
--- /dev/null
+++ b/patches/remove_autoconf_vars.patch
@@ -0,0 +1,18 @@
+Index: openvpn/include/openvpn-plugin.h
+===================================================================
+--- openvpn.orig/include/openvpn-plugin.h
++++ openvpn/include/openvpn-plugin.h
+@@ -49,13 +49,6 @@ typedef X509 openvpn_x509_cert_t;
+ extern "C" {
+ #endif
+ 
+-/* Provide some basic version information to plug-ins at OpenVPN compile time
+- * This is will not be the complete version
+- */
+-#define OPENVPN_VERSION_MAJOR @OPENVPN_VERSION_MAJOR@
+-#define OPENVPN_VERSION_MINOR @OPENVPN_VERSION_MINOR@
+-#define OPENVPN_VERSION_PATCH "@OPENVPN_VERSION_PATCH@"
+-
+ /*
+  * Plug-in types.  These types correspond to the set of script callbacks
+  * supported by OpenVPN.
diff --git a/patches/series b/patches/series
new file mode 100644
index 0000000..73fef3e
--- /dev/null
+++ b/patches/series
@@ -0,0 +1,4 @@
+remove_autoconf_vars.patch
+add_missing_licenses.patch
+cleanup_makefiles.patch
+fix_long_password.patch
diff --git a/src/Makefile.am b/src/Makefile.am
new file mode 100644
index 0000000..14bca42
--- /dev/null
+++ b/src/Makefile.am
@@ -0,0 +1,15 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in
+
+SUBDIRS = compat openvpn plugins
diff --git a/src/compat/Makefile.am b/src/compat/Makefile.am
new file mode 100644
index 0000000..b4c3a4a
--- /dev/null
+++ b/src/compat/Makefile.am
@@ -0,0 +1,30 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in
+
+EXTRA_DIST = \
+	compat.vcxproj \
+	compat.vcxproj.filters
+
+noinst_LTLIBRARIES = libcompat.la
+
+libcompat_la_SOURCES = \
+	compat.h \
+	compat-dirname.c \
+	compat-basename.c \
+	compat-gettimeofday.c \
+	compat-daemon.c \
+	compat-inet_ntop.c \
+	compat-inet_pton.c \
+	compat-lz4.c compat-lz4.h \
+	compat-versionhelpers.h
diff --git a/src/compat/compat-basename.c b/src/compat/compat-basename.c
new file mode 100644
index 0000000..e66e225
--- /dev/null
+++ b/src/compat/compat-basename.c
@@ -0,0 +1,50 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifndef HAVE_BASENAME
+
+#include "compat.h"
+#include <string.h>
+
+/* Modified version based on glibc-2.14.1 by Roland McGrath <roland@gnu.org>
+ * This version is extended to handle both / and \ in path names
+ */
+char *
+basename(char *filename)
+{
+    char *p = strrchr(filename, '/');
+    if (!p)
+    {
+        /* If NULL, check for \ instead ... might be Windows a path */
+        p = strrchr(filename, '\\');
+    }
+    return p ? p + 1 : (char *) filename;
+}
+
+#endif /* HAVE_BASENAME */
diff --git a/src/compat/compat-daemon.c b/src/compat/compat-daemon.c
new file mode 100644
index 0000000..4ef28fa
--- /dev/null
+++ b/src/compat/compat-daemon.c
@@ -0,0 +1,109 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifndef HAVE_DAEMON
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+
+int
+daemon(int nochdir, int noclose)
+{
+#if defined(HAVE_FORK) && defined(HAVE_SETSID)
+    switch (fork())
+    {
+        case -1:
+            return (-1);
+
+        case 0:
+            break;
+
+        default:
+            exit(0);
+    }
+
+    if (setsid() == -1)
+    {
+        return (-1);
+    }
+
+    if (!nochdir)
+    {
+        chdir("/");
+    }
+
+    if (!noclose)
+    {
+#if defined(HAVE_DUP) && defined(HAVE_DUP2)
+        int fd;
+        if ((fd = open("/dev/null", O_RDWR, 0)) != -1)
+        {
+            dup2(fd, 0);
+            dup2(fd, 1);
+            dup2(fd, 2);
+            if (fd > 2)
+            {
+                close(fd);
+            }
+        }
+#endif
+    }
+
+    return 0;
+#else  /* if defined(HAVE_FORK) && defined(HAVE_SETSID) */
+    (void)nochdir;
+    (void)noclose;
+    errno = EFAULT;
+    return -1;
+#endif /* if defined(HAVE_FORK) && defined(HAVE_SETSID) */
+}
+
+#endif /* ifndef HAVE_DAEMON */
+
diff --git a/src/compat/compat-dirname.c b/src/compat/compat-dirname.c
new file mode 100644
index 0000000..c1523d9
--- /dev/null
+++ b/src/compat/compat-dirname.c
@@ -0,0 +1,146 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+
+#ifndef HAVE_DIRNAME
+
+#include "compat.h"
+#include <string.h>
+
+/* Unoptimised version of glibc memrchr().
+ * This is considered fast enough, as only this compat
+ * version of dirname() depends on it.
+ */
+static const char *
+__memrchr(const char *str, int c, size_t n)
+{
+    const char *end = str;
+
+    end += n - 1; /* Go to the end of the string */
+    while (end >= str)
+    {
+        if (c == *end)
+        {
+            return end;
+        }
+        else
+        {
+            end--;
+        }
+    }
+    return NULL;
+}
+
+/* Modified version based on glibc-2.14.1 by Ulrich Drepper <drepper@akkadia.org>
+ * This version is extended to handle both / and \ in path names.
+ */
+char *
+dirname(char *path)
+{
+    static const char dot[] = ".";
+    char *last_slash;
+    char separator = '/';
+
+    /* Find last '/'.  */
+    last_slash = path != NULL ? strrchr(path, '/') : NULL;
+    /* If NULL, check for \ instead ... might be Windows a path */
+    if (!last_slash)
+    {
+        last_slash = path != NULL ? strrchr(path, '\\') : NULL;
+        separator = last_slash ? '\\' : '/'; /* Change the separator if \ was found */
+    }
+
+    if (last_slash != NULL && last_slash != path && last_slash[1] == '\0')
+    {
+        /* Determine whether all remaining characters are slashes.  */
+        char *runp;
+
+        for (runp = last_slash; runp != path; --runp)
+        {
+            if (runp[-1] != separator)
+            {
+                break;
+            }
+        }
+
+        /* The '/' is the last character, we have to look further.  */
+        if (runp != path)
+        {
+            last_slash = (char *) __memrchr(path, separator, runp - path);
+        }
+    }
+
+    if (last_slash != NULL)
+    {
+        /* Determine whether all remaining characters are slashes.  */
+        char *runp;
+
+        for (runp = last_slash; runp != path; --runp)
+        {
+            if (runp[-1] != separator)
+            {
+                break;
+            }
+        }
+
+        /* Terminate the path.  */
+        if (runp == path)
+        {
+            /* The last slash is the first character in the string.  We have to
+             * return "/".  As a special case we have to return "//" if there
+             * are exactly two slashes at the beginning of the string.  See
+             * XBD 4.10 Path Name Resolution for more information.  */
+            if (last_slash == path + 1)
+            {
+                ++last_slash;
+            }
+            else
+            {
+                last_slash = path + 1;
+            }
+        }
+        else
+        {
+            last_slash = runp;
+        }
+
+        last_slash[0] = '\0';
+    }
+    else
+    {
+        /* This assignment is ill-designed but the XPG specs require to
+         * return a string containing "." in any case no directory part is
+         * found and so a static and constant string is required.  */
+        path = (char *) dot;
+    }
+
+    return path;
+}
+
+#endif /* HAVE_DIRNAME */
diff --git a/src/compat/compat-gettimeofday.c b/src/compat/compat-gettimeofday.c
new file mode 100644
index 0000000..7cae641
--- /dev/null
+++ b/src/compat/compat-gettimeofday.c
@@ -0,0 +1,134 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifndef HAVE_GETTIMEOFDAY
+
+#include "compat.h"
+
+#ifdef _WIN32
+/*
+ * NOTICE: mingw has much faster gettimeofday!
+ * autoconf will set HAVE_GETTIMEOFDAY
+ */
+
+#include <windows.h>
+#include <time.h>
+
+static time_t gtc_base = 0;
+static DWORD gtc_last = 0;
+static time_t last_sec = 0;
+static unsigned int last_msec = 0;
+static int bt_last = 0;
+
+static void
+gettimeofday_calibrate(void)
+{
+    const time_t t = time(NULL);
+    const DWORD gtc = GetTickCount();
+    gtc_base = t - gtc/1000;
+    gtc_last = gtc;
+}
+
+/*
+ * Rewritten by JY for OpenVPN 2.1, after I realized that
+ * QueryPerformanceCounter takes nearly 2 orders of magnitude
+ * more processor cycles than GetTickCount.
+ */
+int
+gettimeofday(struct timeval *tv, void *tz)
+{
+    const DWORD gtc = GetTickCount();
+    int bt = 0;
+    time_t sec;
+    unsigned int msec;
+    const int backtrack_hold_seconds = 10;
+
+    (void)tz;
+
+    /* recalibrate at the dreaded 49.7 day mark */
+    if (!gtc_base || gtc < gtc_last)
+    {
+        gettimeofday_calibrate();
+    }
+    gtc_last = gtc;
+
+    sec = gtc_base + gtc / 1000;
+    msec = gtc % 1000;
+
+    if (sec == last_sec)
+    {
+        if (msec < last_msec)
+        {
+            msec = last_msec;
+            bt = 1;
+        }
+    }
+    else if (sec < last_sec)
+    {
+        /* We try to dampen out backtracks of less than backtrack_hold_seconds.
+         * Larger backtracks will be passed through and dealt with by the
+         * TIME_BACKTRACK_PROTECTION code (if enabled) */
+        if (sec > last_sec - backtrack_hold_seconds)
+        {
+            sec = last_sec;
+            msec = last_msec;
+        }
+        bt = 1;
+    }
+
+    tv->tv_sec = (long)last_sec = (long)sec;
+    tv->tv_usec = (last_msec = msec) * 1000;
+
+    if (bt && !bt_last)
+    {
+        gettimeofday_calibrate();
+    }
+    bt_last = bt;
+
+    return 0;
+}
+
+#else  /* ifdef _WIN32 */
+
+#ifdef HAVE_TIME_H
+#include <time.h>
+#endif
+
+int
+gettimeofday(struct timeval *tv, void *tz)
+{
+    (void)tz;
+    tv->tv_sec = time(NULL);
+    tv->tv_usec = 0;
+    return 0;
+}
+
+#endif /* _WIN32 */
+
+#endif /* HAVE_GETTIMEOFDAY */
diff --git a/src/compat/compat-inet_ntop.c b/src/compat/compat-inet_ntop.c
new file mode 100644
index 0000000..f2a181e
--- /dev/null
+++ b/src/compat/compat-inet_ntop.c
@@ -0,0 +1,78 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifndef HAVE_INET_NTOP
+
+#include "compat.h"
+
+#ifdef _WIN32
+
+#include <windows.h>
+
+/*
+ * inet_ntop() and inet_pton() wrap-implementations using
+ * WSAAddressToString() and WSAStringToAddress() functions
+ *
+ * this is needed as long as we support running OpenVPN on WinXP
+ */
+
+const char *
+inet_ntop(int af, const void *src, char *dst, socklen_t size)
+{
+    struct sockaddr_storage ss;
+    unsigned long s = size;
+
+    ZeroMemory(&ss, sizeof(ss));
+    ss.ss_family = af;
+
+    switch (af)
+    {
+        case AF_INET:
+            ((struct sockaddr_in *)&ss)->sin_addr = *(struct in_addr *)src;
+            break;
+
+        case AF_INET6:
+            ((struct sockaddr_in6 *)&ss)->sin6_addr = *(struct in6_addr *)src;
+            break;
+
+        default:
+            return NULL;
+    }
+    /* cannot direclty use &size because of strict aliasing rules */
+    return (WSAAddressToString((struct sockaddr *)&ss, sizeof(ss), NULL, dst, &s) == 0) ?
+           dst : NULL;
+}
+
+#else  /* ifdef _WIN32 */
+
+#error no emulation for inet_ntop
+
+#endif /* ifdef _WIN32 */
+
+#endif /* ifndef HAVE_INET_NTOP */
diff --git a/src/compat/compat-inet_pton.c b/src/compat/compat-inet_pton.c
new file mode 100644
index 0000000..9d451cc
--- /dev/null
+++ b/src/compat/compat-inet_pton.c
@@ -0,0 +1,81 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifndef HAVE_INET_PTON
+
+#include "compat.h"
+
+#ifdef _WIN32
+
+#include <windows.h>
+#include <string.h>
+
+/*
+ * inet_ntop() and inet_pton() wrap-implementations using
+ * WSAAddressToString() and WSAStringToAddress() functions
+ *
+ * this is needed as long as we support running OpenVPN on WinXP
+ */
+
+
+int
+inet_pton(int af, const char *src, void *dst)
+{
+    struct sockaddr_storage ss;
+    int size = sizeof(ss);
+    char src_copy[INET6_ADDRSTRLEN+1];
+
+    ZeroMemory(&ss, sizeof(ss));
+    /* stupid non-const API */
+    strncpy(src_copy, src, INET6_ADDRSTRLEN+1);
+    src_copy[INET6_ADDRSTRLEN] = 0;
+
+    if (WSAStringToAddress(src_copy, af, NULL, (struct sockaddr *)&ss, &size) == 0)
+    {
+        switch (af)
+        {
+            case AF_INET:
+                *(struct in_addr *)dst = ((struct sockaddr_in *)&ss)->sin_addr;
+                return 1;
+
+            case AF_INET6:
+                *(struct in6_addr *)dst = ((struct sockaddr_in6 *)&ss)->sin6_addr;
+                return 1;
+        }
+    }
+    return 0;
+}
+
+#else  /* ifdef _WIN32 */
+
+#error no emulation for inet_ntop
+
+#endif /* ifdef _WIN32 */
+
+#endif /* ifndef HAVE_INET_PTON */
diff --git a/src/compat/compat-lz4.c b/src/compat/compat-lz4.c
new file mode 100644
index 0000000..723157d
--- /dev/null
+++ b/src/compat/compat-lz4.c
@@ -0,0 +1,1474 @@
+/* This file has been backported by dev-tools/lz4-rebaser.sh
+ * from upstream lz4 commit 7bb64ff2b69a9f8367de (v1.7.5)
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifdef NEED_COMPAT_LZ4
+/*
+   LZ4 - Fast LZ compression algorithm
+   Copyright (C) 2011-2016, Yann Collet.
+
+   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+   You can contact the author at :
+    - LZ4 homepage : http://www.lz4.org
+    - LZ4 source repository : https://github.com/lz4/lz4
+*/
+
+
+/*-************************************
+*  Tuning parameters
+**************************************/
+/*
+ * HEAPMODE :
+ * Select how default compression functions will allocate memory for their hash table,
+ * in memory stack (0:default, fastest), or in memory heap (1:requires malloc()).
+ */
+#ifndef HEAPMODE
+#  define HEAPMODE 0
+#endif
+
+/*
+ * ACCELERATION_DEFAULT :
+ * Select "acceleration" for LZ4_compress_fast() when parameter value <= 0
+ */
+#define ACCELERATION_DEFAULT 1
+
+
+/*-************************************
+*  CPU Feature Detection
+**************************************/
+/* LZ4_FORCE_MEMORY_ACCESS
+ * By default, access to unaligned memory is controlled by `memcpy()`, which is safe and portable.
+ * Unfortunately, on some target/compiler combinations, the generated assembly is sub-optimal.
+ * The below switch allow to select different access method for improved performance.
+ * Method 0 (default) : use `memcpy()`. Safe and portable.
+ * Method 1 : `__packed` statement. It depends on compiler extension (ie, not portable).
+ *            This method is safe if your compiler supports it, and *generally* as fast or faster than `memcpy`.
+ * Method 2 : direct access. This method is portable but violate C standard.
+ *            It can generate buggy code on targets which generate assembly depending on alignment.
+ *            But in some circumstances, it's the only known way to get the most performance (ie GCC + ARMv6)
+ * See https://fastcompression.blogspot.fr/2015/08/accessing-unaligned-memory.html for details.
+ * Prefer these methods in priority order (0 > 1 > 2)
+ */
+#ifndef LZ4_FORCE_MEMORY_ACCESS   /* can be defined externally, on command line for example */
+#  if defined(__GNUC__) && ( defined(__ARM_ARCH_6__) || defined(__ARM_ARCH_6J__) || defined(__ARM_ARCH_6K__) || defined(__ARM_ARCH_6Z__) || defined(__ARM_ARCH_6ZK__) || defined(__ARM_ARCH_6T2__) )
+#    define LZ4_FORCE_MEMORY_ACCESS 2
+#  elif defined(__INTEL_COMPILER) || \
+  (defined(__GNUC__) && ( defined(__ARM_ARCH_7__) || defined(__ARM_ARCH_7A__) || defined(__ARM_ARCH_7R__) || defined(__ARM_ARCH_7M__) || defined(__ARM_ARCH_7S__) ))
+#    define LZ4_FORCE_MEMORY_ACCESS 1
+#  endif
+#endif
+
+/*
+ * LZ4_FORCE_SW_BITCOUNT
+ * Define this parameter if your target system or compiler does not support hardware bit count
+ */
+#if defined(_MSC_VER) && defined(_WIN32_WCE)   /* Visual Studio for Windows CE does not support Hardware bit count */
+#  define LZ4_FORCE_SW_BITCOUNT
+#endif
+
+
+/*-************************************
+*  Dependency
+**************************************/
+#include "compat-lz4.h"
+/* see also "memory routines" below */
+
+
+/*-************************************
+*  Compiler Options
+**************************************/
+#ifdef _MSC_VER    /* Visual Studio */
+#  define FORCE_INLINE static __forceinline
+#  include <intrin.h>
+#  pragma warning(disable : 4127)        /* disable: C4127: conditional expression is constant */
+#  pragma warning(disable : 4293)        /* disable: C4293: too large shift (32-bits) */
+#else
+#  if defined(__GNUC__) || defined(__clang__)
+#    define FORCE_INLINE static inline __attribute__((always_inline))
+#  elif defined(__cplusplus) || (defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
+#    define FORCE_INLINE static inline
+#  else
+#    define FORCE_INLINE static
+#  endif
+#endif  /* _MSC_VER */
+
+#if (defined(__GNUC__) && (__GNUC__ >= 3)) || (defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 800)) || defined(__clang__)
+#  define expect(expr,value)    (__builtin_expect ((expr),(value)) )
+#else
+#  define expect(expr,value)    (expr)
+#endif
+
+#define likely(expr)     expect((expr) != 0, 1)
+#define unlikely(expr)   expect((expr) != 0, 0)
+
+
+/*-************************************
+*  Memory routines
+**************************************/
+#include <stdlib.h>   /* malloc, calloc, free */
+#define ALLOCATOR(n,s) calloc(n,s)
+#define FREEMEM        free
+#include <string.h>   /* memset, memcpy */
+#define MEM_INIT       memset
+
+
+/*-************************************
+*  Basic Types
+**************************************/
+#if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
+# include <stdint.h>
+  typedef  uint8_t BYTE;
+  typedef uint16_t U16;
+  typedef uint32_t U32;
+  typedef  int32_t S32;
+  typedef uint64_t U64;
+  typedef uintptr_t uptrval;
+#else
+  typedef unsigned char       BYTE;
+  typedef unsigned short      U16;
+  typedef unsigned int        U32;
+  typedef   signed int        S32;
+  typedef unsigned long long  U64;
+  typedef size_t              uptrval;   /* generally true, except OpenVMS-64 */
+#endif
+
+#if defined(__x86_64__)
+  typedef U64    reg_t;   /* 64-bits in x32 mode */
+#else
+  typedef size_t reg_t;   /* 32-bits in x32 mode */
+#endif
+
+/*-************************************
+*  Reading and writing into memory
+**************************************/
+static unsigned LZ4_isLittleEndian(void)
+{
+    const union { U32 u; BYTE c[4]; } one = { 1 };   /* don't use static : performance detrimental */
+    return one.c[0];
+}
+
+
+#if defined(LZ4_FORCE_MEMORY_ACCESS) && (LZ4_FORCE_MEMORY_ACCESS==2)
+/* lie to the compiler about data alignment; use with caution */
+
+static U16 LZ4_read16(const void* memPtr) { return *(const U16*) memPtr; }
+static U32 LZ4_read32(const void* memPtr) { return *(const U32*) memPtr; }
+static reg_t LZ4_read_ARCH(const void* memPtr) { return *(const reg_t*) memPtr; }
+
+static void LZ4_write16(void* memPtr, U16 value) { *(U16*)memPtr = value; }
+static void LZ4_write32(void* memPtr, U32 value) { *(U32*)memPtr = value; }
+
+#elif defined(LZ4_FORCE_MEMORY_ACCESS) && (LZ4_FORCE_MEMORY_ACCESS==1)
+
+/* __pack instructions are safer, but compiler specific, hence potentially problematic for some compilers */
+/* currently only defined for gcc and icc */
+typedef union { U16 u16; U32 u32; reg_t uArch; } __attribute__((packed)) unalign;
+
+static U16 LZ4_read16(const void* ptr) { return ((const unalign*)ptr)->u16; }
+static U32 LZ4_read32(const void* ptr) { return ((const unalign*)ptr)->u32; }
+static reg_t LZ4_read_ARCH(const void* ptr) { return ((const unalign*)ptr)->uArch; }
+
+static void LZ4_write16(void* memPtr, U16 value) { ((unalign*)memPtr)->u16 = value; }
+static void LZ4_write32(void* memPtr, U32 value) { ((unalign*)memPtr)->u32 = value; }
+
+#else  /* safe and portable access through memcpy() */
+
+static U16 LZ4_read16(const void* memPtr)
+{
+    U16 val; memcpy(&val, memPtr, sizeof(val)); return val;
+}
+
+static U32 LZ4_read32(const void* memPtr)
+{
+    U32 val; memcpy(&val, memPtr, sizeof(val)); return val;
+}
+
+static reg_t LZ4_read_ARCH(const void* memPtr)
+{
+    reg_t val; memcpy(&val, memPtr, sizeof(val)); return val;
+}
+
+static void LZ4_write16(void* memPtr, U16 value)
+{
+    memcpy(memPtr, &value, sizeof(value));
+}
+
+static void LZ4_write32(void* memPtr, U32 value)
+{
+    memcpy(memPtr, &value, sizeof(value));
+}
+
+#endif /* LZ4_FORCE_MEMORY_ACCESS */
+
+
+static U16 LZ4_readLE16(const void* memPtr)
+{
+    if (LZ4_isLittleEndian()) {
+        return LZ4_read16(memPtr);
+    } else {
+        const BYTE* p = (const BYTE*)memPtr;
+        return (U16)((U16)p[0] + (p[1]<<8));
+    }
+}
+
+static void LZ4_writeLE16(void* memPtr, U16 value)
+{
+    if (LZ4_isLittleEndian()) {
+        LZ4_write16(memPtr, value);
+    } else {
+        BYTE* p = (BYTE*)memPtr;
+        p[0] = (BYTE) value;
+        p[1] = (BYTE)(value>>8);
+    }
+}
+
+static void LZ4_copy8(void* dst, const void* src)
+{
+    memcpy(dst,src,8);
+}
+
+/* customized variant of memcpy, which can overwrite up to 8 bytes beyond dstEnd */
+static void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd)
+{
+    BYTE* d = (BYTE*)dstPtr;
+    const BYTE* s = (const BYTE*)srcPtr;
+    BYTE* const e = (BYTE*)dstEnd;
+
+    do { LZ4_copy8(d,s); d+=8; s+=8; } while (d<e);
+}
+
+
+/*-************************************
+*  Common Constants
+**************************************/
+#define MINMATCH 4
+
+#define WILDCOPYLENGTH 8
+#define LASTLITERALS 5
+#define MFLIMIT (WILDCOPYLENGTH+MINMATCH)
+static const int LZ4_minLength = (MFLIMIT+1);
+
+#define KB *(1 <<10)
+#define MB *(1 <<20)
+#define GB *(1U<<30)
+
+#define MAXD_LOG 16
+#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)
+
+#define ML_BITS  4
+#define ML_MASK  ((1U<<ML_BITS)-1)
+#define RUN_BITS (8-ML_BITS)
+#define RUN_MASK ((1U<<RUN_BITS)-1)
+
+
+/*-************************************
+*  Common Utils
+**************************************/
+#define LZ4_STATIC_ASSERT(c)    { enum { LZ4_static_assert = 1/(int)(!!(c)) }; }   /* use only *after* variable declarations */
+
+
+/*-************************************
+*  Common functions
+**************************************/
+static unsigned LZ4_NbCommonBytes (register reg_t val)
+{
+    if (LZ4_isLittleEndian()) {
+        if (sizeof(val)==8) {
+#       if defined(_MSC_VER) && defined(_WIN64) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            unsigned long r = 0;
+            _BitScanForward64( &r, (U64)val );
+            return (int)(r>>3);
+#       elif (defined(__clang__) || (defined(__GNUC__) && (__GNUC__>=3))) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            return (__builtin_ctzll((U64)val) >> 3);
+#       else
+            static const int DeBruijnBytePos[64] = { 0, 0, 0, 0, 0, 1, 1, 2, 0, 3, 1, 3, 1, 4, 2, 7, 0, 2, 3, 6, 1, 5, 3, 5, 1, 3, 4, 4, 2, 5, 6, 7, 7, 0, 1, 2, 3, 3, 4, 6, 2, 6, 5, 5, 3, 4, 5, 6, 7, 1, 2, 4, 6, 4, 4, 5, 7, 2, 6, 5, 7, 6, 7, 7 };
+            return DeBruijnBytePos[((U64)((val & -(long long)val) * 0x0218A392CDABBD3FULL)) >> 58];
+#       endif
+        } else /* 32 bits */ {
+#       if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            unsigned long r;
+            _BitScanForward( &r, (U32)val );
+            return (int)(r>>3);
+#       elif (defined(__clang__) || (defined(__GNUC__) && (__GNUC__>=3))) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            return (__builtin_ctz((U32)val) >> 3);
+#       else
+            static const int DeBruijnBytePos[32] = { 0, 0, 3, 0, 3, 1, 3, 0, 3, 2, 2, 1, 3, 2, 0, 1, 3, 3, 1, 2, 2, 2, 2, 0, 3, 1, 2, 0, 1, 0, 1, 1 };
+            return DeBruijnBytePos[((U32)((val & -(S32)val) * 0x077CB531U)) >> 27];
+#       endif
+        }
+    } else   /* Big Endian CPU */ {
+        if (sizeof(val)==8) {
+#       if defined(_MSC_VER) && defined(_WIN64) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            unsigned long r = 0;
+            _BitScanReverse64( &r, val );
+            return (unsigned)(r>>3);
+#       elif (defined(__clang__) || (defined(__GNUC__) && (__GNUC__>=3))) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            return (__builtin_clzll((U64)val) >> 3);
+#       else
+            unsigned r;
+            if (!(val>>32)) { r=4; } else { r=0; val>>=32; }
+            if (!(val>>16)) { r+=2; val>>=8; } else { val>>=24; }
+            r += (!val);
+            return r;
+#       endif
+        } else /* 32 bits */ {
+#       if defined(_MSC_VER) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            unsigned long r = 0;
+            _BitScanReverse( &r, (unsigned long)val );
+            return (unsigned)(r>>3);
+#       elif (defined(__clang__) || (defined(__GNUC__) && (__GNUC__>=3))) && !defined(LZ4_FORCE_SW_BITCOUNT)
+            return (__builtin_clz((U32)val) >> 3);
+#       else
+            unsigned r;
+            if (!(val>>16)) { r=2; val>>=8; } else { r=0; val>>=24; }
+            r += (!val);
+            return r;
+#       endif
+        }
+    }
+}
+
+#define STEPSIZE sizeof(reg_t)
+static unsigned LZ4_count(const BYTE* pIn, const BYTE* pMatch, const BYTE* pInLimit)
+{
+    const BYTE* const pStart = pIn;
+
+    while (likely(pIn<pInLimit-(STEPSIZE-1))) {
+        reg_t const diff = LZ4_read_ARCH(pMatch) ^ LZ4_read_ARCH(pIn);
+        if (!diff) { pIn+=STEPSIZE; pMatch+=STEPSIZE; continue; }
+        pIn += LZ4_NbCommonBytes(diff);
+        return (unsigned)(pIn - pStart);
+    }
+
+    if ((STEPSIZE==8) && (pIn<(pInLimit-3)) && (LZ4_read32(pMatch) == LZ4_read32(pIn))) { pIn+=4; pMatch+=4; }
+    if ((pIn<(pInLimit-1)) && (LZ4_read16(pMatch) == LZ4_read16(pIn))) { pIn+=2; pMatch+=2; }
+    if ((pIn<pInLimit) && (*pMatch == *pIn)) pIn++;
+    return (unsigned)(pIn - pStart);
+}
+
+
+#ifndef LZ4_COMMONDEFS_ONLY
+/*-************************************
+*  Local Constants
+**************************************/
+static const int LZ4_64Klimit = ((64 KB) + (MFLIMIT-1));
+static const U32 LZ4_skipTrigger = 6;  /* Increase this value ==> compression run slower on incompressible data */
+
+
+/*-************************************
+*  Local Structures and types
+**************************************/
+typedef enum { notLimited = 0, limitedOutput = 1 } limitedOutput_directive;
+typedef enum { byPtr, byU32, byU16 } tableType_t;
+
+typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
+typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;
+
+typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
+typedef enum { full = 0, partial = 1 } earlyEnd_directive;
+
+
+/*-************************************
+*  Local Utils
+**************************************/
+int LZ4_versionNumber (void) { return LZ4_VERSION_NUMBER; }
+const char* LZ4_versionString(void) { return LZ4_VERSION_STRING; }
+int LZ4_compressBound(int isize)  { return LZ4_COMPRESSBOUND(isize); }
+int LZ4_sizeofState() { return LZ4_STREAMSIZE; }
+
+
+/*-******************************
+*  Compression functions
+********************************/
+static U32 LZ4_hash4(U32 sequence, tableType_t const tableType)
+{
+    if (tableType == byU16)
+        return ((sequence * 2654435761U) >> ((MINMATCH*8)-(LZ4_HASHLOG+1)));
+    else
+        return ((sequence * 2654435761U) >> ((MINMATCH*8)-LZ4_HASHLOG));
+}
+
+static U32 LZ4_hash5(U64 sequence, tableType_t const tableType)
+{
+    static const U64 prime5bytes = 889523592379ULL;
+    static const U64 prime8bytes = 11400714785074694791ULL;
+    const U32 hashLog = (tableType == byU16) ? LZ4_HASHLOG+1 : LZ4_HASHLOG;
+    if (LZ4_isLittleEndian())
+        return (U32)(((sequence << 24) * prime5bytes) >> (64 - hashLog));
+    else
+        return (U32)(((sequence >> 24) * prime8bytes) >> (64 - hashLog));
+}
+
+FORCE_INLINE U32 LZ4_hashPosition(const void* const p, tableType_t const tableType)
+{
+    if ((sizeof(reg_t)==8) && (tableType != byU16)) return LZ4_hash5(LZ4_read_ARCH(p), tableType);
+    return LZ4_hash4(LZ4_read32(p), tableType);
+}
+
+static void LZ4_putPositionOnHash(const BYTE* p, U32 h, void* tableBase, tableType_t const tableType, const BYTE* srcBase)
+{
+    switch (tableType)
+    {
+    case byPtr: { const BYTE** hashTable = (const BYTE**)tableBase; hashTable[h] = p; return; }
+    case byU32: { U32* hashTable = (U32*) tableBase; hashTable[h] = (U32)(p-srcBase); return; }
+    case byU16: { U16* hashTable = (U16*) tableBase; hashTable[h] = (U16)(p-srcBase); return; }
+    }
+}
+
+FORCE_INLINE void LZ4_putPosition(const BYTE* p, void* tableBase, tableType_t tableType, const BYTE* srcBase)
+{
+    U32 const h = LZ4_hashPosition(p, tableType);
+    LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
+}
+
+static const BYTE* LZ4_getPositionOnHash(U32 h, void* tableBase, tableType_t tableType, const BYTE* srcBase)
+{
+    if (tableType == byPtr) { const BYTE** hashTable = (const BYTE**) tableBase; return hashTable[h]; }
+    if (tableType == byU32) { const U32* const hashTable = (U32*) tableBase; return hashTable[h] + srcBase; }
+    { const U16* const hashTable = (U16*) tableBase; return hashTable[h] + srcBase; }   /* default, to ensure a return */
+}
+
+FORCE_INLINE const BYTE* LZ4_getPosition(const BYTE* p, void* tableBase, tableType_t tableType, const BYTE* srcBase)
+{
+    U32 const h = LZ4_hashPosition(p, tableType);
+    return LZ4_getPositionOnHash(h, tableBase, tableType, srcBase);
+}
+
+
+/** LZ4_compress_generic() :
+    inlined, to ensure branches are decided at compilation time */
+FORCE_INLINE int LZ4_compress_generic(
+                 LZ4_stream_t_internal* const cctx,
+                 const char* const source,
+                 char* const dest,
+                 const int inputSize,
+                 const int maxOutputSize,
+                 const limitedOutput_directive outputLimited,
+                 const tableType_t tableType,
+                 const dict_directive dict,
+                 const dictIssue_directive dictIssue,
+                 const U32 acceleration)
+{
+    const BYTE* ip = (const BYTE*) source;
+    const BYTE* base;
+    const BYTE* lowLimit;
+    const BYTE* const lowRefLimit = ip - cctx->dictSize;
+    const BYTE* const dictionary = cctx->dictionary;
+    const BYTE* const dictEnd = dictionary + cctx->dictSize;
+    const ptrdiff_t dictDelta = dictEnd - (const BYTE*)source;
+    const BYTE* anchor = (const BYTE*) source;
+    const BYTE* const iend = ip + inputSize;
+    const BYTE* const mflimit = iend - MFLIMIT;
+    const BYTE* const matchlimit = iend - LASTLITERALS;
+
+    BYTE* op = (BYTE*) dest;
+    BYTE* const olimit = op + maxOutputSize;
+
+    U32 forwardH;
+
+    /* Init conditions */
+    if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) return 0;   /* Unsupported inputSize, too large (or negative) */
+    switch(dict)
+    {
+    case noDict:
+    default:
+        base = (const BYTE*)source;
+        lowLimit = (const BYTE*)source;
+        break;
+    case withPrefix64k:
+        base = (const BYTE*)source - cctx->currentOffset;
+        lowLimit = (const BYTE*)source - cctx->dictSize;
+        break;
+    case usingExtDict:
+        base = (const BYTE*)source - cctx->currentOffset;
+        lowLimit = (const BYTE*)source;
+        break;
+    }
+    if ((tableType == byU16) && (inputSize>=LZ4_64Klimit)) return 0;   /* Size too large (not within 64K limit) */
+    if (inputSize<LZ4_minLength) goto _last_literals;                  /* Input too small, no compression (all literals) */
+
+    /* First Byte */
+    LZ4_putPosition(ip, cctx->hashTable, tableType, base);
+    ip++; forwardH = LZ4_hashPosition(ip, tableType);
+
+    /* Main Loop */
+    for ( ; ; ) {
+        ptrdiff_t refDelta = 0;
+        const BYTE* match;
+        BYTE* token;
+
+        /* Find a match */
+        {   const BYTE* forwardIp = ip;
+            unsigned step = 1;
+            unsigned searchMatchNb = acceleration << LZ4_skipTrigger;
+            do {
+                U32 const h = forwardH;
+                ip = forwardIp;
+                forwardIp += step;
+                step = (searchMatchNb++ >> LZ4_skipTrigger);
+
+                if (unlikely(forwardIp > mflimit)) goto _last_literals;
+
+                match = LZ4_getPositionOnHash(h, cctx->hashTable, tableType, base);
+                if (dict==usingExtDict) {
+                    if (match < (const BYTE*)source) {
+                        refDelta = dictDelta;
+                        lowLimit = dictionary;
+                    } else {
+                        refDelta = 0;
+                        lowLimit = (const BYTE*)source;
+                }   }
+                forwardH = LZ4_hashPosition(forwardIp, tableType);
+                LZ4_putPositionOnHash(ip, h, cctx->hashTable, tableType, base);
+
+            } while ( ((dictIssue==dictSmall) ? (match < lowRefLimit) : 0)
+                || ((tableType==byU16) ? 0 : (match + MAX_DISTANCE < ip))
+                || (LZ4_read32(match+refDelta) != LZ4_read32(ip)) );
+        }
+
+        /* Catch up */
+        while (((ip>anchor) & (match+refDelta > lowLimit)) && (unlikely(ip[-1]==match[refDelta-1]))) { ip--; match--; }
+
+        /* Encode Literals */
+        {   unsigned const litLength = (unsigned)(ip - anchor);
+            token = op++;
+            if ((outputLimited) &&  /* Check output buffer overflow */
+                (unlikely(op + litLength + (2 + 1 + LASTLITERALS) + (litLength/255) > olimit)))
+                return 0;
+            if (litLength >= RUN_MASK) {
+                int len = (int)litLength-RUN_MASK;
+                *token = (RUN_MASK<<ML_BITS);
+                for(; len >= 255 ; len-=255) *op++ = 255;
+                *op++ = (BYTE)len;
+            }
+            else *token = (BYTE)(litLength<<ML_BITS);
+
+            /* Copy Literals */
+            LZ4_wildCopy(op, anchor, op+litLength);
+            op+=litLength;
+        }
+
+_next_match:
+        /* Encode Offset */
+        LZ4_writeLE16(op, (U16)(ip-match)); op+=2;
+
+        /* Encode MatchLength */
+        {   unsigned matchCode;
+
+            if ((dict==usingExtDict) && (lowLimit==dictionary)) {
+                const BYTE* limit;
+                match += refDelta;
+                limit = ip + (dictEnd-match);
+                if (limit > matchlimit) limit = matchlimit;
+                matchCode = LZ4_count(ip+MINMATCH, match+MINMATCH, limit);
+                ip += MINMATCH + matchCode;
+                if (ip==limit) {
+                    unsigned const more = LZ4_count(ip, (const BYTE*)source, matchlimit);
+                    matchCode += more;
+                    ip += more;
+                }
+            } else {
+                matchCode = LZ4_count(ip+MINMATCH, match+MINMATCH, matchlimit);
+                ip += MINMATCH + matchCode;
+            }
+
+            if ( outputLimited &&    /* Check output buffer overflow */
+                (unlikely(op + (1 + LASTLITERALS) + (matchCode>>8) > olimit)) )
+                return 0;
+            if (matchCode >= ML_MASK) {
+                *token += ML_MASK;
+                matchCode -= ML_MASK;
+                LZ4_write32(op, 0xFFFFFFFF);
+                while (matchCode >= 4*255) op+=4, LZ4_write32(op, 0xFFFFFFFF), matchCode -= 4*255;
+                op += matchCode / 255;
+                *op++ = (BYTE)(matchCode % 255);
+            } else
+                *token += (BYTE)(matchCode);
+        }
+
+        anchor = ip;
+
+        /* Test end of chunk */
+        if (ip > mflimit) break;
+
+        /* Fill table */
+        LZ4_putPosition(ip-2, cctx->hashTable, tableType, base);
+
+        /* Test next position */
+        match = LZ4_getPosition(ip, cctx->hashTable, tableType, base);
+        if (dict==usingExtDict) {
+            if (match < (const BYTE*)source) {
+                refDelta = dictDelta;
+                lowLimit = dictionary;
+            } else {
+                refDelta = 0;
+                lowLimit = (const BYTE*)source;
+        }   }
+        LZ4_putPosition(ip, cctx->hashTable, tableType, base);
+        if ( ((dictIssue==dictSmall) ? (match>=lowRefLimit) : 1)
+            && (match+MAX_DISTANCE>=ip)
+            && (LZ4_read32(match+refDelta)==LZ4_read32(ip)) )
+        { token=op++; *token=0; goto _next_match; }
+
+        /* Prepare next loop */
+        forwardH = LZ4_hashPosition(++ip, tableType);
+    }
+
+_last_literals:
+    /* Encode Last Literals */
+    {   size_t const lastRun = (size_t)(iend - anchor);
+        if ( (outputLimited) &&  /* Check output buffer overflow */
+            ((op - (BYTE*)dest) + lastRun + 1 + ((lastRun+255-RUN_MASK)/255) > (U32)maxOutputSize) )
+            return 0;
+        if (lastRun >= RUN_MASK) {
+            size_t accumulator = lastRun - RUN_MASK;
+            *op++ = RUN_MASK << ML_BITS;
+            for(; accumulator >= 255 ; accumulator-=255) *op++ = 255;
+            *op++ = (BYTE) accumulator;
+        } else {
+            *op++ = (BYTE)(lastRun<<ML_BITS);
+        }
+        memcpy(op, anchor, lastRun);
+        op += lastRun;
+    }
+
+    /* End */
+    return (int) (((char*)op)-dest);
+}
+
+
+int LZ4_compress_fast_extState(void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int acceleration)
+{
+    LZ4_stream_t_internal* ctx = &((LZ4_stream_t*)state)->internal_donotuse;
+    LZ4_resetStream((LZ4_stream_t*)state);
+    if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
+
+    if (maxOutputSize >= LZ4_compressBound(inputSize)) {
+        if (inputSize < LZ4_64Klimit)
+            return LZ4_compress_generic(ctx, source, dest, inputSize,             0,    notLimited,                        byU16, noDict, noDictIssue, acceleration);
+        else
+            return LZ4_compress_generic(ctx, source, dest, inputSize,             0,    notLimited, (sizeof(void*)==8) ? byU32 : byPtr, noDict, noDictIssue, acceleration);
+    } else {
+        if (inputSize < LZ4_64Klimit)
+            return LZ4_compress_generic(ctx, source, dest, inputSize, maxOutputSize, limitedOutput,                        byU16, noDict, noDictIssue, acceleration);
+        else
+            return LZ4_compress_generic(ctx, source, dest, inputSize, maxOutputSize, limitedOutput, (sizeof(void*)==8) ? byU32 : byPtr, noDict, noDictIssue, acceleration);
+    }
+}
+
+
+int LZ4_compress_fast(const char* source, char* dest, int inputSize, int maxOutputSize, int acceleration)
+{
+#if (HEAPMODE)
+    void* ctxPtr = ALLOCATOR(1, sizeof(LZ4_stream_t));   /* malloc-calloc always properly aligned */
+#else
+    LZ4_stream_t ctx;
+    void* const ctxPtr = &ctx;
+#endif
+
+    int const result = LZ4_compress_fast_extState(ctxPtr, source, dest, inputSize, maxOutputSize, acceleration);
+
+#if (HEAPMODE)
+    FREEMEM(ctxPtr);
+#endif
+    return result;
+}
+
+
+int LZ4_compress_default(const char* source, char* dest, int inputSize, int maxOutputSize)
+{
+    return LZ4_compress_fast(source, dest, inputSize, maxOutputSize, 1);
+}
+
+
+/* hidden debug function */
+/* strangely enough, gcc generates faster code when this function is uncommented, even if unused */
+int LZ4_compress_fast_force(const char* source, char* dest, int inputSize, int maxOutputSize, int acceleration)
+{
+    LZ4_stream_t ctx;
+    LZ4_resetStream(&ctx);
+
+    if (inputSize < LZ4_64Klimit)
+        return LZ4_compress_generic(&ctx.internal_donotuse, source, dest, inputSize, maxOutputSize, limitedOutput, byU16,                        noDict, noDictIssue, acceleration);
+    else
+        return LZ4_compress_generic(&ctx.internal_donotuse, source, dest, inputSize, maxOutputSize, limitedOutput, sizeof(void*)==8 ? byU32 : byPtr, noDict, noDictIssue, acceleration);
+}
+
+
+/*-******************************
+*  *_destSize() variant
+********************************/
+
+static int LZ4_compress_destSize_generic(
+                       LZ4_stream_t_internal* const ctx,
+                 const char* const src,
+                       char* const dst,
+                       int*  const srcSizePtr,
+                 const int targetDstSize,
+                 const tableType_t tableType)
+{
+    const BYTE* ip = (const BYTE*) src;
+    const BYTE* base = (const BYTE*) src;
+    const BYTE* lowLimit = (const BYTE*) src;
+    const BYTE* anchor = ip;
+    const BYTE* const iend = ip + *srcSizePtr;
+    const BYTE* const mflimit = iend - MFLIMIT;
+    const BYTE* const matchlimit = iend - LASTLITERALS;
+
+    BYTE* op = (BYTE*) dst;
+    BYTE* const oend = op + targetDstSize;
+    BYTE* const oMaxLit = op + targetDstSize - 2 /* offset */ - 8 /* because 8+MINMATCH==MFLIMIT */ - 1 /* token */;
+    BYTE* const oMaxMatch = op + targetDstSize - (LASTLITERALS + 1 /* token */);
+    BYTE* const oMaxSeq = oMaxLit - 1 /* token */;
+
+    U32 forwardH;
+
+
+    /* Init conditions */
+    if (targetDstSize < 1) return 0;                                     /* Impossible to store anything */
+    if ((U32)*srcSizePtr > (U32)LZ4_MAX_INPUT_SIZE) return 0;            /* Unsupported input size, too large (or negative) */
+    if ((tableType == byU16) && (*srcSizePtr>=LZ4_64Klimit)) return 0;   /* Size too large (not within 64K limit) */
+    if (*srcSizePtr<LZ4_minLength) goto _last_literals;                  /* Input too small, no compression (all literals) */
+
+    /* First Byte */
+    *srcSizePtr = 0;
+    LZ4_putPosition(ip, ctx->hashTable, tableType, base);
+    ip++; forwardH = LZ4_hashPosition(ip, tableType);
+
+    /* Main Loop */
+    for ( ; ; ) {
+        const BYTE* match;
+        BYTE* token;
+
+        /* Find a match */
+        {   const BYTE* forwardIp = ip;
+            unsigned step = 1;
+            unsigned searchMatchNb = 1 << LZ4_skipTrigger;
+
+            do {
+                U32 h = forwardH;
+                ip = forwardIp;
+                forwardIp += step;
+                step = (searchMatchNb++ >> LZ4_skipTrigger);
+
+                if (unlikely(forwardIp > mflimit)) goto _last_literals;
+
+                match = LZ4_getPositionOnHash(h, ctx->hashTable, tableType, base);
+                forwardH = LZ4_hashPosition(forwardIp, tableType);
+                LZ4_putPositionOnHash(ip, h, ctx->hashTable, tableType, base);
+
+            } while ( ((tableType==byU16) ? 0 : (match + MAX_DISTANCE < ip))
+                || (LZ4_read32(match) != LZ4_read32(ip)) );
+        }
+
+        /* Catch up */
+        while ((ip>anchor) && (match > lowLimit) && (unlikely(ip[-1]==match[-1]))) { ip--; match--; }
+
+        /* Encode Literal length */
+        {   unsigned litLength = (unsigned)(ip - anchor);
+            token = op++;
+            if (op + ((litLength+240)/255) + litLength > oMaxLit) {
+                /* Not enough space for a last match */
+                op--;
+                goto _last_literals;
+            }
+            if (litLength>=RUN_MASK) {
+                unsigned len = litLength - RUN_MASK;
+                *token=(RUN_MASK<<ML_BITS);
+                for(; len >= 255 ; len-=255) *op++ = 255;
+                *op++ = (BYTE)len;
+            }
+            else *token = (BYTE)(litLength<<ML_BITS);
+
+            /* Copy Literals */
+            LZ4_wildCopy(op, anchor, op+litLength);
+            op += litLength;
+        }
+
+_next_match:
+        /* Encode Offset */
+        LZ4_writeLE16(op, (U16)(ip-match)); op+=2;
+
+        /* Encode MatchLength */
+        {   size_t matchLength = LZ4_count(ip+MINMATCH, match+MINMATCH, matchlimit);
+
+            if (op + ((matchLength+240)/255) > oMaxMatch) {
+                /* Match description too long : reduce it */
+                matchLength = (15-1) + (oMaxMatch-op) * 255;
+            }
+            ip += MINMATCH + matchLength;
+
+            if (matchLength>=ML_MASK) {
+                *token += ML_MASK;
+                matchLength -= ML_MASK;
+                while (matchLength >= 255) { matchLength-=255; *op++ = 255; }
+                *op++ = (BYTE)matchLength;
+            }
+            else *token += (BYTE)(matchLength);
+        }
+
+        anchor = ip;
+
+        /* Test end of block */
+        if (ip > mflimit) break;
+        if (op > oMaxSeq) break;
+
+        /* Fill table */
+        LZ4_putPosition(ip-2, ctx->hashTable, tableType, base);
+
+        /* Test next position */
+        match = LZ4_getPosition(ip, ctx->hashTable, tableType, base);
+        LZ4_putPosition(ip, ctx->hashTable, tableType, base);
+        if ( (match+MAX_DISTANCE>=ip)
+            && (LZ4_read32(match)==LZ4_read32(ip)) )
+        { token=op++; *token=0; goto _next_match; }
+
+        /* Prepare next loop */
+        forwardH = LZ4_hashPosition(++ip, tableType);
+    }
+
+_last_literals:
+    /* Encode Last Literals */
+    {   size_t lastRunSize = (size_t)(iend - anchor);
+        if (op + 1 /* token */ + ((lastRunSize+240)/255) /* litLength */ + lastRunSize /* literals */ > oend) {
+            /* adapt lastRunSize to fill 'dst' */
+            lastRunSize  = (oend-op) - 1;
+            lastRunSize -= (lastRunSize+240)/255;
+        }
+        ip = anchor + lastRunSize;
+
+        if (lastRunSize >= RUN_MASK) {
+            size_t accumulator = lastRunSize - RUN_MASK;
+            *op++ = RUN_MASK << ML_BITS;
+            for(; accumulator >= 255 ; accumulator-=255) *op++ = 255;
+            *op++ = (BYTE) accumulator;
+        } else {
+            *op++ = (BYTE)(lastRunSize<<ML_BITS);
+        }
+        memcpy(op, anchor, lastRunSize);
+        op += lastRunSize;
+    }
+
+    /* End */
+    *srcSizePtr = (int) (((const char*)ip)-src);
+    return (int) (((char*)op)-dst);
+}
+
+
+static int LZ4_compress_destSize_extState (LZ4_stream_t* state, const char* src, char* dst, int* srcSizePtr, int targetDstSize)
+{
+    LZ4_resetStream(state);
+
+    if (targetDstSize >= LZ4_compressBound(*srcSizePtr)) {  /* compression success is guaranteed */
+        return LZ4_compress_fast_extState(state, src, dst, *srcSizePtr, targetDstSize, 1);
+    } else {
+        if (*srcSizePtr < LZ4_64Klimit)
+            return LZ4_compress_destSize_generic(&state->internal_donotuse, src, dst, srcSizePtr, targetDstSize, byU16);
+        else
+            return LZ4_compress_destSize_generic(&state->internal_donotuse, src, dst, srcSizePtr, targetDstSize, sizeof(void*)==8 ? byU32 : byPtr);
+    }
+}
+
+
+int LZ4_compress_destSize(const char* src, char* dst, int* srcSizePtr, int targetDstSize)
+{
+#if (HEAPMODE)
+    LZ4_stream_t* ctx = (LZ4_stream_t*)ALLOCATOR(1, sizeof(LZ4_stream_t));   /* malloc-calloc always properly aligned */
+#else
+    LZ4_stream_t ctxBody;
+    LZ4_stream_t* ctx = &ctxBody;
+#endif
+
+    int result = LZ4_compress_destSize_extState(ctx, src, dst, srcSizePtr, targetDstSize);
+
+#if (HEAPMODE)
+    FREEMEM(ctx);
+#endif
+    return result;
+}
+
+
+
+/*-******************************
+*  Streaming functions
+********************************/
+
+LZ4_stream_t* LZ4_createStream(void)
+{
+    LZ4_stream_t* lz4s = (LZ4_stream_t*)ALLOCATOR(8, LZ4_STREAMSIZE_U64);
+    LZ4_STATIC_ASSERT(LZ4_STREAMSIZE >= sizeof(LZ4_stream_t_internal));    /* A compilation error here means LZ4_STREAMSIZE is not large enough */
+    LZ4_resetStream(lz4s);
+    return lz4s;
+}
+
+void LZ4_resetStream (LZ4_stream_t* LZ4_stream)
+{
+    MEM_INIT(LZ4_stream, 0, sizeof(LZ4_stream_t));
+}
+
+int LZ4_freeStream (LZ4_stream_t* LZ4_stream)
+{
+    FREEMEM(LZ4_stream);
+    return (0);
+}
+
+
+#define HASH_UNIT sizeof(reg_t)
+int LZ4_loadDict (LZ4_stream_t* LZ4_dict, const char* dictionary, int dictSize)
+{
+    LZ4_stream_t_internal* dict = &LZ4_dict->internal_donotuse;
+    const BYTE* p = (const BYTE*)dictionary;
+    const BYTE* const dictEnd = p + dictSize;
+    const BYTE* base;
+
+    if ((dict->initCheck) || (dict->currentOffset > 1 GB))  /* Uninitialized structure, or reuse overflow */
+        LZ4_resetStream(LZ4_dict);
+
+    if (dictSize < (int)HASH_UNIT) {
+        dict->dictionary = NULL;
+        dict->dictSize = 0;
+        return 0;
+    }
+
+    if ((dictEnd - p) > 64 KB) p = dictEnd - 64 KB;
+    dict->currentOffset += 64 KB;
+    base = p - dict->currentOffset;
+    dict->dictionary = p;
+    dict->dictSize = (U32)(dictEnd - p);
+    dict->currentOffset += dict->dictSize;
+
+    while (p <= dictEnd-HASH_UNIT) {
+        LZ4_putPosition(p, dict->hashTable, byU32, base);
+        p+=3;
+    }
+
+    return dict->dictSize;
+}
+
+
+static void LZ4_renormDictT(LZ4_stream_t_internal* LZ4_dict, const BYTE* src)
+{
+    if ((LZ4_dict->currentOffset > 0x80000000) ||
+        ((uptrval)LZ4_dict->currentOffset > (uptrval)src)) {   /* address space overflow */
+        /* rescale hash table */
+        U32 const delta = LZ4_dict->currentOffset - 64 KB;
+        const BYTE* dictEnd = LZ4_dict->dictionary + LZ4_dict->dictSize;
+        int i;
+        for (i=0; i<LZ4_HASH_SIZE_U32; i++) {
+            if (LZ4_dict->hashTable[i] < delta) LZ4_dict->hashTable[i]=0;
+            else LZ4_dict->hashTable[i] -= delta;
+        }
+        LZ4_dict->currentOffset = 64 KB;
+        if (LZ4_dict->dictSize > 64 KB) LZ4_dict->dictSize = 64 KB;
+        LZ4_dict->dictionary = dictEnd - LZ4_dict->dictSize;
+    }
+}
+
+
+int LZ4_compress_fast_continue (LZ4_stream_t* LZ4_stream, const char* source, char* dest, int inputSize, int maxOutputSize, int acceleration)
+{
+    LZ4_stream_t_internal* streamPtr = &LZ4_stream->internal_donotuse;
+    const BYTE* const dictEnd = streamPtr->dictionary + streamPtr->dictSize;
+
+    const BYTE* smallest = (const BYTE*) source;
+    if (streamPtr->initCheck) return 0;   /* Uninitialized structure detected */
+    if ((streamPtr->dictSize>0) && (smallest>dictEnd)) smallest = dictEnd;
+    LZ4_renormDictT(streamPtr, smallest);
+    if (acceleration < 1) acceleration = ACCELERATION_DEFAULT;
+
+    /* Check overlapping input/dictionary space */
+    {   const BYTE* sourceEnd = (const BYTE*) source + inputSize;
+        if ((sourceEnd > streamPtr->dictionary) && (sourceEnd < dictEnd)) {
+            streamPtr->dictSize = (U32)(dictEnd - sourceEnd);
+            if (streamPtr->dictSize > 64 KB) streamPtr->dictSize = 64 KB;
+            if (streamPtr->dictSize < 4) streamPtr->dictSize = 0;
+            streamPtr->dictionary = dictEnd - streamPtr->dictSize;
+        }
+    }
+
+    /* prefix mode : source data follows dictionary */
+    if (dictEnd == (const BYTE*)source) {
+        int result;
+        if ((streamPtr->dictSize < 64 KB) && (streamPtr->dictSize < streamPtr->currentOffset))
+            result = LZ4_compress_generic(streamPtr, source, dest, inputSize, maxOutputSize, limitedOutput, byU32, withPrefix64k, dictSmall, acceleration);
+        else
+            result = LZ4_compress_generic(streamPtr, source, dest, inputSize, maxOutputSize, limitedOutput, byU32, withPrefix64k, noDictIssue, acceleration);
+        streamPtr->dictSize += (U32)inputSize;
+        streamPtr->currentOffset += (U32)inputSize;
+        return result;
+    }
+
+    /* external dictionary mode */
+    {   int result;
+        if ((streamPtr->dictSize < 64 KB) && (streamPtr->dictSize < streamPtr->currentOffset))
+            result = LZ4_compress_generic(streamPtr, source, dest, inputSize, maxOutputSize, limitedOutput, byU32, usingExtDict, dictSmall, acceleration);
+        else
+            result = LZ4_compress_generic(streamPtr, source, dest, inputSize, maxOutputSize, limitedOutput, byU32, usingExtDict, noDictIssue, acceleration);
+        streamPtr->dictionary = (const BYTE*)source;
+        streamPtr->dictSize = (U32)inputSize;
+        streamPtr->currentOffset += (U32)inputSize;
+        return result;
+    }
+}
+
+
+/* Hidden debug function, to force external dictionary mode */
+int LZ4_compress_forceExtDict (LZ4_stream_t* LZ4_dict, const char* source, char* dest, int inputSize)
+{
+    LZ4_stream_t_internal* streamPtr = &LZ4_dict->internal_donotuse;
+    int result;
+    const BYTE* const dictEnd = streamPtr->dictionary + streamPtr->dictSize;
+
+    const BYTE* smallest = dictEnd;
+    if (smallest > (const BYTE*) source) smallest = (const BYTE*) source;
+    LZ4_renormDictT(streamPtr, smallest);
+
+    result = LZ4_compress_generic(streamPtr, source, dest, inputSize, 0, notLimited, byU32, usingExtDict, noDictIssue, 1);
+
+    streamPtr->dictionary = (const BYTE*)source;
+    streamPtr->dictSize = (U32)inputSize;
+    streamPtr->currentOffset += (U32)inputSize;
+
+    return result;
+}
+
+
+/*! LZ4_saveDict() :
+ *  If previously compressed data block is not guaranteed to remain available at its memory location,
+ *  save it into a safer place (char* safeBuffer).
+ *  Note : you don't need to call LZ4_loadDict() afterwards,
+ *         dictionary is immediately usable, you can therefore call LZ4_compress_fast_continue().
+ *  Return : saved dictionary size in bytes (necessarily <= dictSize), or 0 if error.
+ */
+int LZ4_saveDict (LZ4_stream_t* LZ4_dict, char* safeBuffer, int dictSize)
+{
+    LZ4_stream_t_internal* const dict = &LZ4_dict->internal_donotuse;
+    const BYTE* const previousDictEnd = dict->dictionary + dict->dictSize;
+
+    if ((U32)dictSize > 64 KB) dictSize = 64 KB;   /* useless to define a dictionary > 64 KB */
+    if ((U32)dictSize > dict->dictSize) dictSize = dict->dictSize;
+
+    memmove(safeBuffer, previousDictEnd - dictSize, dictSize);
+
+    dict->dictionary = (const BYTE*)safeBuffer;
+    dict->dictSize = (U32)dictSize;
+
+    return dictSize;
+}
+
+
+
+/*-*****************************
+*  Decompression functions
+*******************************/
+/*! LZ4_decompress_generic() :
+ *  This generic decompression function cover all use cases.
+ *  It shall be instantiated several times, using different sets of directives
+ *  Note that it is important this generic function is really inlined,
+ *  in order to remove useless branches during compilation optimization.
+ */
+FORCE_INLINE int LZ4_decompress_generic(
+                 const char* const source,
+                 char* const dest,
+                 int inputSize,
+                 int outputSize,         /* If endOnInput==endOnInputSize, this value is the max size of Output Buffer. */
+
+                 int endOnInput,         /* endOnOutputSize, endOnInputSize */
+                 int partialDecoding,    /* full, partial */
+                 int targetOutputSize,   /* only used if partialDecoding==partial */
+                 int dict,               /* noDict, withPrefix64k, usingExtDict */
+                 const BYTE* const lowPrefix,  /* == dest when no prefix */
+                 const BYTE* const dictStart,  /* only if dict==usingExtDict */
+                 const size_t dictSize         /* note : = 0 if noDict */
+                 )
+{
+    /* Local Variables */
+    const BYTE* ip = (const BYTE*) source;
+    const BYTE* const iend = ip + inputSize;
+
+    BYTE* op = (BYTE*) dest;
+    BYTE* const oend = op + outputSize;
+    BYTE* cpy;
+    BYTE* oexit = op + targetOutputSize;
+    const BYTE* const lowLimit = lowPrefix - dictSize;
+
+    const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize;
+    const unsigned dec32table[] = {0, 1, 2, 1, 4, 4, 4, 4};
+    const int dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};
+
+    const int safeDecode = (endOnInput==endOnInputSize);
+    const int checkOffset = ((safeDecode) && (dictSize < (int)(64 KB)));
+
+
+    /* Special cases */
+    if ((partialDecoding) && (oexit > oend-MFLIMIT)) oexit = oend-MFLIMIT;                        /* targetOutputSize too high => decode everything */
+    if ((endOnInput) && (unlikely(outputSize==0))) return ((inputSize==1) && (*ip==0)) ? 0 : -1;  /* Empty output buffer */
+    if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1);
+
+    /* Main Loop : decode sequences */
+    while (1) {
+        size_t length;
+        const BYTE* match;
+        size_t offset;
+
+        /* get literal length */
+        unsigned const token = *ip++;
+        if ((length=(token>>ML_BITS)) == RUN_MASK) {
+            unsigned s;
+            do {
+                s = *ip++;
+                length += s;
+            } while ( likely(endOnInput ? ip<iend-RUN_MASK : 1) & (s==255) );
+            if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)(op))) goto _output_error;   /* overflow detection */
+            if ((safeDecode) && unlikely((uptrval)(ip)+length<(uptrval)(ip))) goto _output_error;   /* overflow detection */
+        }
+
+        /* copy literals */
+        cpy = op+length;
+        if ( ((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) )
+            || ((!endOnInput) && (cpy>oend-WILDCOPYLENGTH)) )
+        {
+            if (partialDecoding) {
+                if (cpy > oend) goto _output_error;                           /* Error : write attempt beyond end of output buffer */
+                if ((endOnInput) && (ip+length > iend)) goto _output_error;   /* Error : read attempt beyond end of input buffer */
+            } else {
+                if ((!endOnInput) && (cpy != oend)) goto _output_error;       /* Error : block decoding must stop exactly there */
+                if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error;   /* Error : input must be consumed */
+            }
+            memcpy(op, ip, length);
+            ip += length;
+            op += length;
+            break;     /* Necessarily EOF, due to parsing restrictions */
+        }
+        LZ4_wildCopy(op, ip, cpy);
+        ip += length; op = cpy;
+
+        /* get offset */
+        offset = LZ4_readLE16(ip); ip+=2;
+        match = op - offset;
+        if ((checkOffset) && (unlikely(match < lowLimit))) goto _output_error;   /* Error : offset outside buffers */
+        LZ4_write32(op, (U32)offset);   /* costs ~1%; silence an msan warning when offset==0 */
+
+        /* get matchlength */
+        length = token & ML_MASK;
+        if (length == ML_MASK) {
+            unsigned s;
+            do {
+                s = *ip++;
+                if ((endOnInput) && (ip > iend-LASTLITERALS)) goto _output_error;
+                length += s;
+            } while (s==255);
+            if ((safeDecode) && unlikely((uptrval)(op)+length<(uptrval)op)) goto _output_error;   /* overflow detection */
+        }
+        length += MINMATCH;
+
+        /* check external dictionary */
+        if ((dict==usingExtDict) && (match < lowPrefix)) {
+            if (unlikely(op+length > oend-LASTLITERALS)) goto _output_error;   /* doesn't respect parsing restriction */
+
+            if (length <= (size_t)(lowPrefix-match)) {
+                /* match can be copied as a single segment from external dictionary */
+                memmove(op, dictEnd - (lowPrefix-match), length);
+                op += length;
+            } else {
+                /* match encompass external dictionary and current block */
+                size_t const copySize = (size_t)(lowPrefix-match);
+                size_t const restSize = length - copySize;
+                memcpy(op, dictEnd - copySize, copySize);
+                op += copySize;
+                if (restSize > (size_t)(op-lowPrefix)) {  /* overlap copy */
+                    BYTE* const endOfMatch = op + restSize;
+                    const BYTE* copyFrom = lowPrefix;
+                    while (op < endOfMatch) *op++ = *copyFrom++;
+                } else {
+                    memcpy(op, lowPrefix, restSize);
+                    op += restSize;
+            }   }
+            continue;
+        }
+
+        /* copy match within block */
+        cpy = op + length;
+        if (unlikely(offset<8)) {
+            const int dec64 = dec64table[offset];
+            op[0] = match[0];
+            op[1] = match[1];
+            op[2] = match[2];
+            op[3] = match[3];
+            match += dec32table[offset];
+            memcpy(op+4, match, 4);
+            match -= dec64;
+        } else { LZ4_copy8(op, match); match+=8; }
+        op += 8;
+
+        if (unlikely(cpy>oend-12)) {
+            BYTE* const oCopyLimit = oend-(WILDCOPYLENGTH-1);
+            if (cpy > oend-LASTLITERALS) goto _output_error;    /* Error : last LASTLITERALS bytes must be literals (uncompressed) */
+            if (op < oCopyLimit) {
+                LZ4_wildCopy(op, match, oCopyLimit);
+                match += oCopyLimit - op;
+                op = oCopyLimit;
+            }
+            while (op<cpy) *op++ = *match++;
+        } else {
+            LZ4_copy8(op, match);
+            if (length>16) LZ4_wildCopy(op+8, match+8, cpy);
+        }
+        op=cpy;   /* correction */
+    }
+
+    /* end of decoding */
+    if (endOnInput)
+       return (int) (((char*)op)-dest);     /* Nb of output bytes decoded */
+    else
+       return (int) (((const char*)ip)-source);   /* Nb of input bytes read */
+
+    /* Overflow error detected */
+_output_error:
+    return (int) (-(((const char*)ip)-source))-1;
+}
+
+
+int LZ4_decompress_safe(const char* source, char* dest, int compressedSize, int maxDecompressedSize)
+{
+    return LZ4_decompress_generic(source, dest, compressedSize, maxDecompressedSize, endOnInputSize, full, 0, noDict, (BYTE*)dest, NULL, 0);
+}
+
+int LZ4_decompress_safe_partial(const char* source, char* dest, int compressedSize, int targetOutputSize, int maxDecompressedSize)
+{
+    return LZ4_decompress_generic(source, dest, compressedSize, maxDecompressedSize, endOnInputSize, partial, targetOutputSize, noDict, (BYTE*)dest, NULL, 0);
+}
+
+int LZ4_decompress_fast(const char* source, char* dest, int originalSize)
+{
+    return LZ4_decompress_generic(source, dest, 0, originalSize, endOnOutputSize, full, 0, withPrefix64k, (BYTE*)(dest - 64 KB), NULL, 64 KB);
+}
+
+
+/*===== streaming decompression functions =====*/
+
+/*
+ * If you prefer dynamic allocation methods,
+ * LZ4_createStreamDecode()
+ * provides a pointer (void*) towards an initialized LZ4_streamDecode_t structure.
+ */
+LZ4_streamDecode_t* LZ4_createStreamDecode(void)
+{
+    LZ4_streamDecode_t* lz4s = (LZ4_streamDecode_t*) ALLOCATOR(1, sizeof(LZ4_streamDecode_t));
+    return lz4s;
+}
+
+int LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream)
+{
+    FREEMEM(LZ4_stream);
+    return 0;
+}
+
+/*!
+ * LZ4_setStreamDecode() :
+ * Use this function to instruct where to find the dictionary.
+ * This function is not necessary if previous data is still available where it was decoded.
+ * Loading a size of 0 is allowed (same effect as no dictionary).
+ * Return : 1 if OK, 0 if error
+ */
+int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const char* dictionary, int dictSize)
+{
+    LZ4_streamDecode_t_internal* lz4sd = &LZ4_streamDecode->internal_donotuse;
+    lz4sd->prefixSize = (size_t) dictSize;
+    lz4sd->prefixEnd = (const BYTE*) dictionary + dictSize;
+    lz4sd->externalDict = NULL;
+    lz4sd->extDictSize  = 0;
+    return 1;
+}
+
+/*
+*_continue() :
+    These decoding functions allow decompression of multiple blocks in "streaming" mode.
+    Previously decoded blocks must still be available at the memory position where they were decoded.
+    If it's not possible, save the relevant part of decoded data into a safe buffer,
+    and indicate where it stands using LZ4_setStreamDecode()
+*/
+int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxOutputSize)
+{
+    LZ4_streamDecode_t_internal* lz4sd = &LZ4_streamDecode->internal_donotuse;
+    int result;
+
+    if (lz4sd->prefixEnd == (BYTE*)dest) {
+        result = LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
+                                        endOnInputSize, full, 0,
+                                        usingExtDict, lz4sd->prefixEnd - lz4sd->prefixSize, lz4sd->externalDict, lz4sd->extDictSize);
+        if (result <= 0) return result;
+        lz4sd->prefixSize += result;
+        lz4sd->prefixEnd  += result;
+    } else {
+        lz4sd->extDictSize = lz4sd->prefixSize;
+        lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
+        result = LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize,
+                                        endOnInputSize, full, 0,
+                                        usingExtDict, (BYTE*)dest, lz4sd->externalDict, lz4sd->extDictSize);
+        if (result <= 0) return result;
+        lz4sd->prefixSize = result;
+        lz4sd->prefixEnd  = (BYTE*)dest + result;
+    }
+
+    return result;
+}
+
+int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int originalSize)
+{
+    LZ4_streamDecode_t_internal* lz4sd = &LZ4_streamDecode->internal_donotuse;
+    int result;
+
+    if (lz4sd->prefixEnd == (BYTE*)dest) {
+        result = LZ4_decompress_generic(source, dest, 0, originalSize,
+                                        endOnOutputSize, full, 0,
+                                        usingExtDict, lz4sd->prefixEnd - lz4sd->prefixSize, lz4sd->externalDict, lz4sd->extDictSize);
+        if (result <= 0) return result;
+        lz4sd->prefixSize += originalSize;
+        lz4sd->prefixEnd  += originalSize;
+    } else {
+        lz4sd->extDictSize = lz4sd->prefixSize;
+        lz4sd->externalDict = lz4sd->prefixEnd - lz4sd->extDictSize;
+        result = LZ4_decompress_generic(source, dest, 0, originalSize,
+                                        endOnOutputSize, full, 0,
+                                        usingExtDict, (BYTE*)dest, lz4sd->externalDict, lz4sd->extDictSize);
+        if (result <= 0) return result;
+        lz4sd->prefixSize = originalSize;
+        lz4sd->prefixEnd  = (BYTE*)dest + originalSize;
+    }
+
+    return result;
+}
+
+
+/*
+Advanced decoding functions :
+*_usingDict() :
+    These decoding functions work the same as "_continue" ones,
+    the dictionary must be explicitly provided within parameters
+*/
+
+FORCE_INLINE int LZ4_decompress_usingDict_generic(const char* source, char* dest, int compressedSize, int maxOutputSize, int safe, const char* dictStart, int dictSize)
+{
+    if (dictSize==0)
+        return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, safe, full, 0, noDict, (BYTE*)dest, NULL, 0);
+    if (dictStart+dictSize == dest) {
+        if (dictSize >= (int)(64 KB - 1))
+            return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, safe, full, 0, withPrefix64k, (BYTE*)dest-64 KB, NULL, 0);
+        return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, safe, full, 0, noDict, (BYTE*)dest-dictSize, NULL, 0);
+    }
+    return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, safe, full, 0, usingExtDict, (BYTE*)dest, (const BYTE*)dictStart, dictSize);
+}
+
+int LZ4_decompress_safe_usingDict(const char* source, char* dest, int compressedSize, int maxOutputSize, const char* dictStart, int dictSize)
+{
+    return LZ4_decompress_usingDict_generic(source, dest, compressedSize, maxOutputSize, 1, dictStart, dictSize);
+}
+
+int LZ4_decompress_fast_usingDict(const char* source, char* dest, int originalSize, const char* dictStart, int dictSize)
+{
+    return LZ4_decompress_usingDict_generic(source, dest, 0, originalSize, 0, dictStart, dictSize);
+}
+
+/* debug function */
+int LZ4_decompress_safe_forceExtDict(const char* source, char* dest, int compressedSize, int maxOutputSize, const char* dictStart, int dictSize)
+{
+    return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, endOnInputSize, full, 0, usingExtDict, (BYTE*)dest, (const BYTE*)dictStart, dictSize);
+}
+
+
+/*=*************************************************
+*  Obsolete Functions
+***************************************************/
+/* obsolete compression functions */
+int LZ4_compress_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize) { return LZ4_compress_default(source, dest, inputSize, maxOutputSize); }
+int LZ4_compress(const char* source, char* dest, int inputSize) { return LZ4_compress_default(source, dest, inputSize, LZ4_compressBound(inputSize)); }
+int LZ4_compress_limitedOutput_withState (void* state, const char* src, char* dst, int srcSize, int dstSize) { return LZ4_compress_fast_extState(state, src, dst, srcSize, dstSize, 1); }
+int LZ4_compress_withState (void* state, const char* src, char* dst, int srcSize) { return LZ4_compress_fast_extState(state, src, dst, srcSize, LZ4_compressBound(srcSize), 1); }
+int LZ4_compress_limitedOutput_continue (LZ4_stream_t* LZ4_stream, const char* src, char* dst, int srcSize, int maxDstSize) { return LZ4_compress_fast_continue(LZ4_stream, src, dst, srcSize, maxDstSize, 1); }
+int LZ4_compress_continue (LZ4_stream_t* LZ4_stream, const char* source, char* dest, int inputSize) { return LZ4_compress_fast_continue(LZ4_stream, source, dest, inputSize, LZ4_compressBound(inputSize), 1); }
+
+/*
+These function names are deprecated and should no longer be used.
+They are only provided here for compatibility with older user programs.
+- LZ4_uncompress is totally equivalent to LZ4_decompress_fast
+- LZ4_uncompress_unknownOutputSize is totally equivalent to LZ4_decompress_safe
+*/
+int LZ4_uncompress (const char* source, char* dest, int outputSize) { return LZ4_decompress_fast(source, dest, outputSize); }
+int LZ4_uncompress_unknownOutputSize (const char* source, char* dest, int isize, int maxOutputSize) { return LZ4_decompress_safe(source, dest, isize, maxOutputSize); }
+
+
+/* Obsolete Streaming functions */
+
+int LZ4_sizeofStreamState() { return LZ4_STREAMSIZE; }
+
+static void LZ4_init(LZ4_stream_t* lz4ds, BYTE* base)
+{
+    MEM_INIT(lz4ds, 0, sizeof(LZ4_stream_t));
+    lz4ds->internal_donotuse.bufferStart = base;
+}
+
+int LZ4_resetStreamState(void* state, char* inputBuffer)
+{
+    if ((((uptrval)state) & 3) != 0) return 1;   /* Error : pointer is not aligned on 4-bytes boundary */
+    LZ4_init((LZ4_stream_t*)state, (BYTE*)inputBuffer);
+    return 0;
+}
+
+void* LZ4_create (char* inputBuffer)
+{
+    LZ4_stream_t* lz4ds = (LZ4_stream_t*)ALLOCATOR(8, sizeof(LZ4_stream_t));
+    LZ4_init (lz4ds, (BYTE*)inputBuffer);
+    return lz4ds;
+}
+
+char* LZ4_slideInputBuffer (void* LZ4_Data)
+{
+    LZ4_stream_t_internal* ctx = &((LZ4_stream_t*)LZ4_Data)->internal_donotuse;
+    int dictSize = LZ4_saveDict((LZ4_stream_t*)LZ4_Data, (char*)ctx->bufferStart, 64 KB);
+    return (char*)(ctx->bufferStart + dictSize);
+}
+
+/* Obsolete streaming decompression functions */
+
+int LZ4_decompress_safe_withPrefix64k(const char* source, char* dest, int compressedSize, int maxOutputSize)
+{
+    return LZ4_decompress_generic(source, dest, compressedSize, maxOutputSize, endOnInputSize, full, 0, withPrefix64k, (BYTE*)dest - 64 KB, NULL, 64 KB);
+}
+
+int LZ4_decompress_fast_withPrefix64k(const char* source, char* dest, int originalSize)
+{
+    return LZ4_decompress_generic(source, dest, 0, originalSize, endOnOutputSize, full, 0, withPrefix64k, (BYTE*)dest - 64 KB, NULL, 64 KB);
+}
+
+#endif   /* LZ4_COMMONDEFS_ONLY */
+#endif /* NEED_COMPAT_LZ4 */
diff --git a/src/compat/compat-lz4.h b/src/compat/compat-lz4.h
new file mode 100644
index 0000000..0aae19c
--- /dev/null
+++ b/src/compat/compat-lz4.h
@@ -0,0 +1,463 @@
+/*
+ *  LZ4 - Fast LZ compression algorithm
+ *  Header File
+ *  Copyright (C) 2011-2016, Yann Collet.
+
+   BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
+
+   Redistribution and use in source and binary forms, with or without
+   modification, are permitted provided that the following conditions are
+   met:
+
+       * Redistributions of source code must retain the above copyright
+   notice, this list of conditions and the following disclaimer.
+       * Redistributions in binary form must reproduce the above
+   copyright notice, this list of conditions and the following disclaimer
+   in the documentation and/or other materials provided with the
+   distribution.
+
+   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+   You can contact the author at :
+    - LZ4 homepage : http://www.lz4.org
+    - LZ4 source repository : https://github.com/lz4/lz4
+*/
+#ifndef LZ4_H_2983827168210
+#define LZ4_H_2983827168210
+
+#if defined (__cplusplus)
+extern "C" {
+#endif
+
+/* --- Dependency --- */
+#include <stddef.h>   /* size_t */
+
+
+/**
+  Introduction
+
+  LZ4 is lossless compression algorithm, providing compression speed at 400 MB/s per core,
+  scalable with multi-cores CPU. It features an extremely fast decoder, with speed in
+  multiple GB/s per core, typically reaching RAM speed limits on multi-core systems.
+
+  The LZ4 compression library provides in-memory compression and decompression functions.
+  Compression can be done in:
+    - a single step (described as Simple Functions)
+    - a single step, reusing a context (described in Advanced Functions)
+    - unbounded multiple steps (described as Streaming compression)
+
+  lz4.h provides block compression functions. It gives full buffer control to user.
+  Decompressing an lz4-compressed block also requires metadata (such as compressed size).
+  Each application is free to encode such metadata in whichever way it wants.
+
+  An additional format, called LZ4 frame specification (doc/lz4_Frame_format.md),
+  take care of encoding standard metadata alongside LZ4-compressed blocks.
+  If your application requires interoperability, it's recommended to use it.
+  A library is provided to take care of it, see lz4frame.h.
+*/
+
+/*^***************************************************************
+*  Export parameters
+*****************************************************************/
+/*
+*  LZ4_DLL_EXPORT :
+*  Enable exporting of functions when building a Windows DLL
+*/
+#if defined(LZ4_DLL_EXPORT) && (LZ4_DLL_EXPORT==1)
+#  define LZ4LIB_API __declspec(dllexport)
+#elif defined(LZ4_DLL_IMPORT) && (LZ4_DLL_IMPORT==1)
+#  define LZ4LIB_API __declspec(dllimport) /* It isn't required but allows to generate better code, saving a function pointer load from the IAT and an indirect jump.*/
+#else
+#  define LZ4LIB_API
+#endif
+
+
+/*========== Version =========== */
+#define LZ4_VERSION_MAJOR    1    /* for breaking interface changes  */
+#define LZ4_VERSION_MINOR    7    /* for new (non-breaking) interface capabilities */
+#define LZ4_VERSION_RELEASE  5    /* for tweaks, bug-fixes, or development */
+
+#define LZ4_VERSION_NUMBER (LZ4_VERSION_MAJOR *100*100 + LZ4_VERSION_MINOR *100 + LZ4_VERSION_RELEASE)
+
+#define LZ4_LIB_VERSION LZ4_VERSION_MAJOR.LZ4_VERSION_MINOR.LZ4_VERSION_RELEASE
+#define LZ4_QUOTE(str) #str
+#define LZ4_EXPAND_AND_QUOTE(str) LZ4_QUOTE(str)
+#define LZ4_VERSION_STRING LZ4_EXPAND_AND_QUOTE(LZ4_LIB_VERSION)
+
+LZ4LIB_API int LZ4_versionNumber (void);
+LZ4LIB_API const char* LZ4_versionString (void);
+
+
+/*-************************************
+*  Tuning parameter
+**************************************/
+/*!
+ * LZ4_MEMORY_USAGE :
+ * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
+ * Increasing memory usage improves compression ratio
+ * Reduced memory usage can improve speed, due to cache effect
+ * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
+ */
+#define LZ4_MEMORY_USAGE 14
+
+
+/*-************************************
+*  Simple Functions
+**************************************/
+/*! LZ4_compress_default() :
+    Compresses 'sourceSize' bytes from buffer 'source'
+    into already allocated 'dest' buffer of size 'maxDestSize'.
+    Compression is guaranteed to succeed if 'maxDestSize' >= LZ4_compressBound(sourceSize).
+    It also runs faster, so it's a recommended setting.
+    If the function cannot compress 'source' into a more limited 'dest' budget,
+    compression stops *immediately*, and the function result is zero.
+    As a consequence, 'dest' content is not valid.
+    This function never writes outside 'dest' buffer, nor read outside 'source' buffer.
+        sourceSize  : Max supported value is LZ4_MAX_INPUT_VALUE
+        maxDestSize : full or partial size of buffer 'dest' (which must be already allocated)
+        return : the number of bytes written into buffer 'dest' (necessarily <= maxOutputSize)
+              or 0 if compression fails */
+LZ4LIB_API int LZ4_compress_default(const char* source, char* dest, int sourceSize, int maxDestSize);
+
+/*! LZ4_decompress_safe() :
+    compressedSize : is the precise full size of the compressed block.
+    maxDecompressedSize : is the size of destination buffer, which must be already allocated.
+    return : the number of bytes decompressed into destination buffer (necessarily <= maxDecompressedSize)
+             If destination buffer is not large enough, decoding will stop and output an error code (<0).
+             If the source stream is detected malformed, the function will stop decoding and return a negative result.
+             This function is protected against buffer overflow exploits, including malicious data packets.
+             It never writes outside output buffer, nor reads outside input buffer.
+*/
+LZ4LIB_API int LZ4_decompress_safe (const char* source, char* dest, int compressedSize, int maxDecompressedSize);
+
+
+/*-************************************
+*  Advanced Functions
+**************************************/
+#define LZ4_MAX_INPUT_SIZE        0x7E000000   /* 2 113 929 216 bytes */
+#define LZ4_COMPRESSBOUND(isize)  ((unsigned)(isize) > (unsigned)LZ4_MAX_INPUT_SIZE ? 0 : (isize) + ((isize)/255) + 16)
+
+/*!
+LZ4_compressBound() :
+    Provides the maximum size that LZ4 compression may output in a "worst case" scenario (input data not compressible)
+    This function is primarily useful for memory allocation purposes (destination buffer size).
+    Macro LZ4_COMPRESSBOUND() is also provided for compilation-time evaluation (stack memory allocation for example).
+    Note that LZ4_compress_default() compress faster when dest buffer size is >= LZ4_compressBound(srcSize)
+        inputSize  : max supported value is LZ4_MAX_INPUT_SIZE
+        return : maximum output size in a "worst case" scenario
+              or 0, if input size is too large ( > LZ4_MAX_INPUT_SIZE)
+*/
+LZ4LIB_API int LZ4_compressBound(int inputSize);
+
+/*!
+LZ4_compress_fast() :
+    Same as LZ4_compress_default(), but allows to select an "acceleration" factor.
+    The larger the acceleration value, the faster the algorithm, but also the lesser the compression.
+    It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed.
+    An acceleration value of "1" is the same as regular LZ4_compress_default()
+    Values <= 0 will be replaced by ACCELERATION_DEFAULT (see lz4.c), which is 1.
+*/
+LZ4LIB_API int LZ4_compress_fast (const char* source, char* dest, int sourceSize, int maxDestSize, int acceleration);
+
+
+/*!
+LZ4_compress_fast_extState() :
+    Same compression function, just using an externally allocated memory space to store compression state.
+    Use LZ4_sizeofState() to know how much memory must be allocated,
+    and allocate it on 8-bytes boundaries (using malloc() typically).
+    Then, provide it as 'void* state' to compression function.
+*/
+LZ4LIB_API int LZ4_sizeofState(void);
+LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* source, char* dest, int inputSize, int maxDestSize, int acceleration);
+
+
+/*!
+LZ4_compress_destSize() :
+    Reverse the logic, by compressing as much data as possible from 'source' buffer
+    into already allocated buffer 'dest' of size 'targetDestSize'.
+    This function either compresses the entire 'source' content into 'dest' if it's large enough,
+    or fill 'dest' buffer completely with as much data as possible from 'source'.
+        *sourceSizePtr : will be modified to indicate how many bytes where read from 'source' to fill 'dest'.
+                         New value is necessarily <= old value.
+        return : Nb bytes written into 'dest' (necessarily <= targetDestSize)
+              or 0 if compression fails
+*/
+LZ4LIB_API int LZ4_compress_destSize (const char* source, char* dest, int* sourceSizePtr, int targetDestSize);
+
+
+/*!
+LZ4_decompress_fast() :
+    originalSize : is the original and therefore uncompressed size
+    return : the number of bytes read from the source buffer (in other words, the compressed size)
+             If the source stream is detected malformed, the function will stop decoding and return a negative result.
+             Destination buffer must be already allocated. Its size must be a minimum of 'originalSize' bytes.
+    note : This function fully respect memory boundaries for properly formed compressed data.
+           It is a bit faster than LZ4_decompress_safe().
+           However, it does not provide any protection against intentionally modified data stream (malicious input).
+           Use this function in trusted environment only (data to decode comes from a trusted source).
+*/
+LZ4LIB_API int LZ4_decompress_fast (const char* source, char* dest, int originalSize);
+
+/*!
+LZ4_decompress_safe_partial() :
+    This function decompress a compressed block of size 'compressedSize' at position 'source'
+    into destination buffer 'dest' of size 'maxDecompressedSize'.
+    The function tries to stop decompressing operation as soon as 'targetOutputSize' has been reached,
+    reducing decompression time.
+    return : the number of bytes decoded in the destination buffer (necessarily <= maxDecompressedSize)
+       Note : this number can be < 'targetOutputSize' should the compressed block to decode be smaller.
+             Always control how many bytes were decoded.
+             If the source stream is detected malformed, the function will stop decoding and return a negative result.
+             This function never writes outside of output buffer, and never reads outside of input buffer. It is therefore protected against malicious data packets
+*/
+LZ4LIB_API int LZ4_decompress_safe_partial (const char* source, char* dest, int compressedSize, int targetOutputSize, int maxDecompressedSize);
+
+
+/*-*********************************************
+*  Streaming Compression Functions
+***********************************************/
+typedef union LZ4_stream_u LZ4_stream_t;   /* incomplete type (defined later) */
+
+/*! LZ4_createStream() and LZ4_freeStream() :
+ *  LZ4_createStream() will allocate and initialize an `LZ4_stream_t` structure.
+ *  LZ4_freeStream() releases its memory.
+ */
+LZ4LIB_API LZ4_stream_t* LZ4_createStream(void);
+LZ4LIB_API int           LZ4_freeStream (LZ4_stream_t* streamPtr);
+
+/*! LZ4_resetStream() :
+ *  An LZ4_stream_t structure can be allocated once and re-used multiple times.
+ *  Use this function to init an allocated `LZ4_stream_t` structure and start a new compression.
+ */
+LZ4LIB_API void LZ4_resetStream (LZ4_stream_t* streamPtr);
+
+/*! LZ4_loadDict() :
+ *  Use this function to load a static dictionary into LZ4_stream.
+ *  Any previous data will be forgotten, only 'dictionary' will remain in memory.
+ *  Loading a size of 0 is allowed.
+ *  Return : dictionary size, in bytes (necessarily <= 64 KB)
+ */
+LZ4LIB_API int LZ4_loadDict (LZ4_stream_t* streamPtr, const char* dictionary, int dictSize);
+
+/*! LZ4_compress_fast_continue() :
+ *  Compress buffer content 'src', using data from previously compressed blocks as dictionary to improve compression ratio.
+ *  Important : Previous data blocks are assumed to still be present and unmodified !
+ *  'dst' buffer must be already allocated.
+ *  If maxDstSize >= LZ4_compressBound(srcSize), compression is guaranteed to succeed, and runs faster.
+ *  If not, and if compressed data cannot fit into 'dst' buffer size, compression stops, and function returns a zero.
+ */
+LZ4LIB_API int LZ4_compress_fast_continue (LZ4_stream_t* streamPtr, const char* src, char* dst, int srcSize, int maxDstSize, int acceleration);
+
+/*! LZ4_saveDict() :
+ *  If previously compressed data block is not guaranteed to remain available at its memory location,
+ *  save it into a safer place (char* safeBuffer).
+ *  Note : you don't need to call LZ4_loadDict() afterwards,
+ *         dictionary is immediately usable, you can therefore call LZ4_compress_fast_continue().
+ *  Return : saved dictionary size in bytes (necessarily <= dictSize), or 0 if error.
+ */
+LZ4LIB_API int LZ4_saveDict (LZ4_stream_t* streamPtr, char* safeBuffer, int dictSize);
+
+
+/*-**********************************************
+*  Streaming Decompression Functions
+*  Bufferless synchronous API
+************************************************/
+typedef union LZ4_streamDecode_u LZ4_streamDecode_t;   /* incomplete type (defined later) */
+
+/* creation / destruction of streaming decompression tracking structure */
+LZ4LIB_API LZ4_streamDecode_t* LZ4_createStreamDecode(void);
+LZ4LIB_API int                 LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream);
+
+/*! LZ4_setStreamDecode() :
+ *  Use this function to instruct where to find the dictionary.
+ *  Setting a size of 0 is allowed (same effect as reset).
+ *  @return : 1 if OK, 0 if error
+ */
+LZ4LIB_API int LZ4_setStreamDecode (LZ4_streamDecode_t* LZ4_streamDecode, const char* dictionary, int dictSize);
+
+/*!
+LZ4_decompress_*_continue() :
+    These decoding functions allow decompression of multiple blocks in "streaming" mode.
+    Previously decoded blocks *must* remain available at the memory position where they were decoded (up to 64 KB)
+    In the case of a ring buffers, decoding buffer must be either :
+    - Exactly same size as encoding buffer, with same update rule (block boundaries at same positions)
+      In which case, the decoding & encoding ring buffer can have any size, including very small ones ( < 64 KB).
+    - Larger than encoding buffer, by a minimum of maxBlockSize more bytes.
+      maxBlockSize is implementation dependent. It's the maximum size you intend to compress into a single block.
+      In which case, encoding and decoding buffers do not need to be synchronized,
+      and encoding ring buffer can have any size, including small ones ( < 64 KB).
+    - _At least_ 64 KB + 8 bytes + maxBlockSize.
+      In which case, encoding and decoding buffers do not need to be synchronized,
+      and encoding ring buffer can have any size, including larger than decoding buffer.
+    Whenever these conditions are not possible, save the last 64KB of decoded data into a safe buffer,
+    and indicate where it is saved using LZ4_setStreamDecode()
+*/
+LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int compressedSize, int maxDecompressedSize);
+LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* source, char* dest, int originalSize);
+
+
+/*! LZ4_decompress_*_usingDict() :
+ *  These decoding functions work the same as
+ *  a combination of LZ4_setStreamDecode() followed by LZ4_decompress_*_continue()
+ *  They are stand-alone, and don't need an LZ4_streamDecode_t structure.
+ */
+LZ4LIB_API int LZ4_decompress_safe_usingDict (const char* source, char* dest, int compressedSize, int maxDecompressedSize, const char* dictStart, int dictSize);
+LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* source, char* dest, int originalSize, const char* dictStart, int dictSize);
+
+
+/*^**********************************************
+ * !!!!!!   STATIC LINKING ONLY   !!!!!!
+ ***********************************************/
+/*-************************************
+ *  Private definitions
+ **************************************
+ * Do not use these definitions.
+ * They are exposed to allow static allocation of `LZ4_stream_t` and `LZ4_streamDecode_t`.
+ * Using these definitions will expose code to API and/or ABI break in future versions of the library.
+ **************************************/
+#define LZ4_HASHLOG   (LZ4_MEMORY_USAGE-2)
+#define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
+#define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)       /* required as macro for static allocation */
+
+#if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
+#include <stdint.h>
+
+typedef struct {
+    uint32_t hashTable[LZ4_HASH_SIZE_U32];
+    uint32_t currentOffset;
+    uint32_t initCheck;
+    const uint8_t* dictionary;
+    uint8_t* bufferStart;   /* obsolete, used for slideInputBuffer */
+    uint32_t dictSize;
+} LZ4_stream_t_internal;
+
+typedef struct {
+    const uint8_t* externalDict;
+    size_t extDictSize;
+    const uint8_t* prefixEnd;
+    size_t prefixSize;
+} LZ4_streamDecode_t_internal;
+
+#else
+
+typedef struct {
+    unsigned int hashTable[LZ4_HASH_SIZE_U32];
+    unsigned int currentOffset;
+    unsigned int initCheck;
+    const unsigned char* dictionary;
+    unsigned char* bufferStart;   /* obsolete, used for slideInputBuffer */
+    unsigned int dictSize;
+} LZ4_stream_t_internal;
+
+typedef struct {
+    const unsigned char* externalDict;
+    size_t extDictSize;
+    const unsigned char* prefixEnd;
+    size_t prefixSize;
+} LZ4_streamDecode_t_internal;
+
+#endif
+
+/*!
+ * LZ4_stream_t :
+ * information structure to track an LZ4 stream.
+ * init this structure before first use.
+ * note : only use in association with static linking !
+ *        this definition is not API/ABI safe,
+ *        and may change in a future version !
+ */
+#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4)
+#define LZ4_STREAMSIZE     (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
+union LZ4_stream_u {
+    unsigned long long table[LZ4_STREAMSIZE_U64];
+    LZ4_stream_t_internal internal_donotuse;
+} ;  /* previously typedef'd to LZ4_stream_t */
+
+
+/*!
+ * LZ4_streamDecode_t :
+ * information structure to track an LZ4 stream during decompression.
+ * init this structure  using LZ4_setStreamDecode (or memset()) before first use
+ * note : only use in association with static linking !
+ *        this definition is not API/ABI safe,
+ *        and may change in a future version !
+ */
+#define LZ4_STREAMDECODESIZE_U64  4
+#define LZ4_STREAMDECODESIZE     (LZ4_STREAMDECODESIZE_U64 * sizeof(unsigned long long))
+union LZ4_streamDecode_u {
+    unsigned long long table[LZ4_STREAMDECODESIZE_U64];
+    LZ4_streamDecode_t_internal internal_donotuse;
+} ;   /* previously typedef'd to LZ4_streamDecode_t */
+
+
+/*=************************************
+*  Obsolete Functions
+**************************************/
+/* Deprecation warnings */
+/* Should these warnings be a problem,
+   it is generally possible to disable them,
+   typically with -Wno-deprecated-declarations for gcc
+   or _CRT_SECURE_NO_WARNINGS in Visual.
+   Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS */
+#ifdef LZ4_DISABLE_DEPRECATE_WARNINGS
+#  define LZ4_DEPRECATED(message)   /* disable deprecation warnings */
+#else
+#  define LZ4_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
+#  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
+#    define LZ4_DEPRECATED(message) [[deprecated(message)]]
+#  elif (LZ4_GCC_VERSION >= 405) || defined(__clang__)
+#    define LZ4_DEPRECATED(message) __attribute__((deprecated(message)))
+#  elif (LZ4_GCC_VERSION >= 301)
+#    define LZ4_DEPRECATED(message) __attribute__((deprecated))
+#  elif defined(_MSC_VER)
+#    define LZ4_DEPRECATED(message) __declspec(deprecated(message))
+#  else
+#    pragma message("WARNING: You need to implement LZ4_DEPRECATED for this compiler")
+#    define LZ4_DEPRECATED(message)
+#  endif
+#endif /* LZ4_DISABLE_DEPRECATE_WARNINGS */
+
+/* Obsolete compression functions */
+LZ4_DEPRECATED("use LZ4_compress_default() instead") int LZ4_compress               (const char* source, char* dest, int sourceSize);
+LZ4_DEPRECATED("use LZ4_compress_default() instead") int LZ4_compress_limitedOutput (const char* source, char* dest, int sourceSize, int maxOutputSize);
+LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") int LZ4_compress_withState               (void* state, const char* source, char* dest, int inputSize);
+LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") int LZ4_compress_limitedOutput_withState (void* state, const char* source, char* dest, int inputSize, int maxOutputSize);
+LZ4_DEPRECATED("use LZ4_compress_fast_continue() instead") int LZ4_compress_continue                (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize);
+LZ4_DEPRECATED("use LZ4_compress_fast_continue() instead") int LZ4_compress_limitedOutput_continue  (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
+
+/* Obsolete decompression functions */
+/* These function names are completely deprecated and must no longer be used.
+   They are only provided in lz4.c for compatibility with older programs.
+    - LZ4_uncompress is the same as LZ4_decompress_fast
+    - LZ4_uncompress_unknownOutputSize is the same as LZ4_decompress_safe
+   These function prototypes are now disabled; uncomment them only if you really need them.
+   It is highly recommended to stop using these prototypes and migrate to maintained ones */
+/* int LZ4_uncompress (const char* source, char* dest, int outputSize); */
+/* int LZ4_uncompress_unknownOutputSize (const char* source, char* dest, int isize, int maxOutputSize); */
+
+/* Obsolete streaming functions; use new streaming interface whenever possible */
+LZ4_DEPRECATED("use LZ4_createStream() instead") void* LZ4_create (char* inputBuffer);
+LZ4_DEPRECATED("use LZ4_createStream() instead") int   LZ4_sizeofStreamState(void);
+LZ4_DEPRECATED("use LZ4_resetStream() instead")  int   LZ4_resetStreamState(void* state, char* inputBuffer);
+LZ4_DEPRECATED("use LZ4_saveDict() instead")     char* LZ4_slideInputBuffer (void* state);
+
+/* Obsolete streaming decoding functions */
+LZ4_DEPRECATED("use LZ4_decompress_safe_usingDict() instead") int LZ4_decompress_safe_withPrefix64k (const char* src, char* dst, int compressedSize, int maxDstSize);
+LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") int LZ4_decompress_fast_withPrefix64k (const char* src, char* dst, int originalSize);
+
+
+#if defined (__cplusplus)
+}
+#endif
+
+#endif /* LZ4_H_2983827168210 */
diff --git a/src/compat/compat-versionhelpers.h b/src/compat/compat-versionhelpers.h
new file mode 100644
index 0000000..251fb04
--- /dev/null
+++ b/src/compat/compat-versionhelpers.h
@@ -0,0 +1,106 @@
+/**
+ * This file is part of the mingw-w64 runtime package.
+ * No warranty is given; refer to the file DISCLAIMER within this package.
+ */
+
+#ifndef _INC_VERSIONHELPERS
+#define _INC_VERSIONHELPERS
+
+#include <winapifamily.h>
+
+#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) && !defined(__WIDL__)
+
+#ifdef __cplusplus
+#define VERSIONHELPERAPI inline bool
+#else
+#define VERSIONHELPERAPI FORCEINLINE BOOL
+#endif
+
+#define _WIN32_WINNT_WINBLUE    0x0603
+
+VERSIONHELPERAPI
+IsWindowsVersionOrGreater(WORD major, WORD minor, WORD servpack)
+{
+    OSVERSIONINFOEXW vi = {sizeof(vi),major,minor,0,0,{0},servpack};
+    return VerifyVersionInfoW(&vi, VER_MAJORVERSION|VER_MINORVERSION|VER_SERVICEPACKMAJOR,
+                              VerSetConditionMask(VerSetConditionMask(VerSetConditionMask(0,
+                                                                                          VER_MAJORVERSION,VER_GREATER_EQUAL),
+                                                                      VER_MINORVERSION,VER_GREATER_EQUAL),
+                                                  VER_SERVICEPACKMAJOR, VER_GREATER_EQUAL));
+}
+
+VERSIONHELPERAPI
+IsWindowsXPOrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WINXP), LOBYTE(_WIN32_WINNT_WINXP), 0);
+}
+
+VERSIONHELPERAPI
+IsWindowsXPSP1OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WINXP), LOBYTE(_WIN32_WINNT_WINXP), 1);
+}
+
+VERSIONHELPERAPI
+IsWindowsXPSP2OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WINXP), LOBYTE(_WIN32_WINNT_WINXP), 2);
+}
+
+VERSIONHELPERAPI
+IsWindowsXPSP3OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WINXP), LOBYTE(_WIN32_WINNT_WINXP), 3);
+}
+
+VERSIONHELPERAPI
+IsWindowsVistaOrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_VISTA), LOBYTE(_WIN32_WINNT_VISTA), 0);
+}
+
+VERSIONHELPERAPI
+IsWindowsVistaSP1OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_VISTA), LOBYTE(_WIN32_WINNT_VISTA), 1);
+}
+
+VERSIONHELPERAPI
+IsWindowsVistaSP2OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_VISTA), LOBYTE(_WIN32_WINNT_VISTA), 2);
+}
+
+VERSIONHELPERAPI
+IsWindows7OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WIN7), LOBYTE(_WIN32_WINNT_WIN7), 0);
+}
+
+VERSIONHELPERAPI
+IsWindows7SP1OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WIN7), LOBYTE(_WIN32_WINNT_WIN7), 1);
+}
+
+VERSIONHELPERAPI
+IsWindows8OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WIN8), LOBYTE(_WIN32_WINNT_WIN8), 0);
+}
+
+VERSIONHELPERAPI
+IsWindows8Point1OrGreater(void)
+{
+    return IsWindowsVersionOrGreater(HIBYTE(_WIN32_WINNT_WINBLUE), LOBYTE(_WIN32_WINNT_WINBLUE), 0);
+}
+
+VERSIONHELPERAPI
+IsWindowsServer(void)
+{
+    OSVERSIONINFOEXW vi = {sizeof(vi),0,0,0,0,{0},0,0,0,VER_NT_WORKSTATION};
+    return !VerifyVersionInfoW(&vi, VER_PRODUCT_TYPE, VerSetConditionMask(0, VER_PRODUCT_TYPE, VER_EQUAL));
+}
+
+#endif /* if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_DESKTOP) && !defined(__WIDL__) */
+#endif /* ifndef _INC_VERSIONHELPERS */
diff --git a/src/compat/compat.h b/src/compat/compat.h
new file mode 100644
index 0000000..d522898
--- /dev/null
+++ b/src/compat/compat.h
@@ -0,0 +1,73 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011 - David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef COMPAT_H
+#define COMPAT_H
+
+#ifdef HAVE_WINSOCK2_H
+#include <winsock2.h>
+#endif
+
+#ifdef HAVE_WS2TCPIP_H
+#include <ws2tcpip.h>
+#endif
+
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+
+#ifndef HAVE_DIRNAME
+char *dirname(char *str);
+
+#endif /* HAVE_DIRNAME */
+
+#ifndef HAVE_BASENAME
+char *basename(char *str);
+
+#endif /* HAVE_BASENAME */
+
+#ifndef HAVE_GETTIMEOFDAY
+int gettimeofday(struct timeval *tv, void *tz);
+
+#endif
+
+#ifndef HAVE_DAEMON
+int daemon(int nochdir, int noclose);
+
+#endif
+
+#ifndef HAVE_INET_NTOP
+const char *inet_ntop(int af, const void *src, char *dst, socklen_t size);
+
+#endif
+
+#ifndef HAVE_INET_PTON
+int inet_pton(int af, const char *src, void *dst);
+
+#endif
+
+#endif /* COMPAT_H */
diff --git a/src/openvpn/Makefile.am b/src/openvpn/Makefile.am
new file mode 100644
index 0000000..1f91e59
--- /dev/null
+++ b/src/openvpn/Makefile.am
@@ -0,0 +1,138 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+include $(top_srcdir)/ltrc.inc
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in
+
+EXTRA_DIST = \
+	openvpn.vcxproj \
+	openvpn.vcxproj.filters
+
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/include \
+	-I$(top_srcdir)/src/compat
+
+AM_CFLAGS = \
+	$(TAP_CFLAGS) \
+	$(OPTIONAL_CRYPTO_CFLAGS) \
+	$(OPTIONAL_LZO_CFLAGS) \
+	$(OPTIONAL_LZ4_CFLAGS) \
+	$(OPTIONAL_PKCS11_HELPER_CFLAGS) \
+	$(OPTIONAL_INOTIFY_CFLAGS) \
+	-DPLUGIN_LIBDIR=\"${plugindir}\"
+
+if WIN32
+# we want unicode entry point but not the macro
+AM_CFLAGS += -municode -UUNICODE
+endif
+
+sbin_PROGRAMS = openvpn
+
+openvpn_SOURCES = \
+	argv.c argv.h \
+	base64.c base64.h \
+	basic.h \
+	buffer.c buffer.h \
+	circ_list.h \
+	clinat.c clinat.h \
+	common.h \
+	comp.c comp.h compstub.c \
+	comp-lz4.c comp-lz4.h \
+	crypto.c crypto.h crypto_backend.h \
+	crypto_openssl.c crypto_openssl.h \
+	crypto_mbedtls.c crypto_mbedtls.h \
+	dhcp.c dhcp.h \
+	errlevel.h \
+	error.c error.h \
+	event.c event.h \
+	fdmisc.c fdmisc.h \
+	forward.c forward.h forward-inline.h \
+	fragment.c fragment.h \
+	gremlin.c gremlin.h \
+	helper.c helper.h \
+	httpdigest.c httpdigest.h \
+	lladdr.c lladdr.h \
+	init.c init.h \
+	integer.h \
+	interval.c interval.h \
+	list.c list.h \
+	lzo.c lzo.h \
+	manage.c manage.h \
+	mbuf.c mbuf.h \
+	memdbg.h \
+	misc.c misc.h \
+	platform.c platform.h \
+	console.c console.h console_builtin.c console_systemd.c \
+	mroute.c mroute.h \
+	mss.c mss.h \
+	mstats.c mstats.h \
+	mtcp.c mtcp.h \
+	mtu.c mtu.h \
+	mudp.c mudp.h \
+	multi.c multi.h \
+	ntlm.c ntlm.h \
+	occ.c occ.h occ-inline.h \
+	openssl_compat.h \
+	pkcs11.c pkcs11.h pkcs11_backend.h \
+	pkcs11_openssl.c \
+	pkcs11_mbedtls.c \
+	openvpn.c openvpn.h \
+	options.c options.h \
+	otime.c otime.h \
+	packet_id.c packet_id.h \
+	perf.c perf.h \
+	pf.c pf.h pf-inline.h \
+	ping.c ping.h ping-inline.h \
+	plugin.c plugin.h \
+	pool.c pool.h \
+	proto.c proto.h \
+	proxy.c proxy.h \
+	ps.c ps.h \
+	push.c push.h \
+	pushlist.h \
+	reliable.c reliable.h \
+	route.c route.h \
+	schedule.c schedule.h \
+	session_id.c session_id.h \
+	shaper.c shaper.h \
+	sig.c sig.h \
+	socket.c socket.h \
+	socks.c socks.h \
+	ssl.c ssl.h  ssl_backend.h \
+	ssl_openssl.c ssl_openssl.h \
+	ssl_mbedtls.c ssl_mbedtls.h \
+	ssl_common.h \
+	ssl_verify.c ssl_verify.h ssl_verify_backend.h \
+	ssl_verify_openssl.c ssl_verify_openssl.h \
+	ssl_verify_mbedtls.c ssl_verify_mbedtls.h \
+	status.c status.h \
+	syshead.h \
+	tls_crypt.c tls_crypt.h \
+	tun.c tun.h \
+	win32.h win32.c \
+	cryptoapi.h cryptoapi.c
+openvpn_LDADD = \
+	$(top_builddir)/src/compat/libcompat.la \
+	$(SOCKETS_LIBS) \
+	$(OPTIONAL_LZO_LIBS) \
+	$(OPTIONAL_LZ4_LIBS) \
+	$(OPTIONAL_PKCS11_HELPER_LIBS) \
+	$(OPTIONAL_CRYPTO_LIBS) \
+	$(OPTIONAL_SELINUX_LIBS) \
+	$(OPTIONAL_SYSTEMD_LIBS) \
+	$(OPTIONAL_DL_LIBS) \
+	$(OPTIONAL_INOTIFY_LIBS)
+if WIN32
+openvpn_SOURCES += openvpn_win32_resources.rc block_dns.c block_dns.h
+openvpn_LDADD += -lgdi32 -lws2_32 -lwininet -lcrypt32 -liphlpapi -lwinmm -lfwpuclnt -lrpcrt4 -lncrypt
+endif
diff --git a/src/openvpn/argv.c b/src/openvpn/argv.c
new file mode 100644
index 0000000..7d06951
--- /dev/null
+++ b/src/openvpn/argv.c
@@ -0,0 +1,360 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ *
+ *  A printf-like function (that only recognizes a subset of standard printf
+ *  format operators) that prints arguments to an argv list instead
+ *  of a standard string.  This is used to build up argv arrays for passing
+ *  to execve.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "argv.h"
+#include "integer.h"
+#include "options.h"
+
+static void
+argv_init(struct argv *a)
+{
+    a->capacity = 0;
+    a->argc = 0;
+    a->argv = NULL;
+}
+
+struct argv
+argv_new(void)
+{
+    struct argv ret;
+    argv_init(&ret);
+    return ret;
+}
+
+void
+argv_reset(struct argv *a)
+{
+    size_t i;
+    for (i = 0; i < a->argc; ++i)
+    {
+        free(a->argv[i]);
+    }
+    free(a->argv);
+    argv_init(a);
+}
+
+static void
+argv_extend(struct argv *a, const size_t newcap)
+{
+    if (newcap > a->capacity)
+    {
+        char **newargv;
+        size_t i;
+        ALLOC_ARRAY_CLEAR(newargv, char *, newcap);
+        for (i = 0; i < a->argc; ++i)
+        {
+            newargv[i] = a->argv[i];
+        }
+        free(a->argv);
+        a->argv = newargv;
+        a->capacity = newcap;
+    }
+}
+
+static void
+argv_grow(struct argv *a, const size_t add)
+{
+    const size_t newargc = a->argc + add + 1;
+    ASSERT(newargc > a->argc);
+    argv_extend(a, adjust_power_of_2(newargc));
+}
+
+static void
+argv_append(struct argv *a, char *str)  /* str must have been malloced or be NULL */
+{
+    argv_grow(a, 1);
+    a->argv[a->argc++] = str;
+}
+
+static struct argv
+argv_clone(const struct argv *a, const size_t headroom)
+{
+    struct argv r;
+    size_t i;
+
+    argv_init(&r);
+    for (i = 0; i < headroom; ++i)
+    {
+        argv_append(&r, NULL);
+    }
+    if (a)
+    {
+        for (i = 0; i < a->argc; ++i)
+        {
+            argv_append(&r, string_alloc(a->argv[i], NULL));
+        }
+    }
+    return r;
+}
+
+struct argv
+argv_insert_head(const struct argv *a, const char *head)
+{
+    struct argv r;
+    r = argv_clone(a, 1);
+    r.argv[0] = string_alloc(head, NULL);
+    return r;
+}
+
+static char *
+argv_term(const char **f)
+{
+    const char *p = *f;
+    const char *term = NULL;
+    size_t termlen = 0;
+
+    if (*p == '\0')
+    {
+        return NULL;
+    }
+
+    while (true)
+    {
+        const int c = *p;
+        if (c == '\0')
+        {
+            break;
+        }
+        if (term)
+        {
+            if (!isspace(c))
+            {
+                ++termlen;
+            }
+            else
+            {
+                break;
+            }
+        }
+        else
+        {
+            if (!isspace(c))
+            {
+                term = p;
+                termlen = 1;
+            }
+        }
+        ++p;
+    }
+    *f = p;
+
+    if (term)
+    {
+        char *ret;
+        ASSERT(termlen > 0);
+        ret = malloc(termlen + 1);
+        check_malloc_return(ret);
+        memcpy(ret, term, termlen);
+        ret[termlen] = '\0';
+        return ret;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+const char *
+argv_str(const struct argv *a, struct gc_arena *gc, const unsigned int flags)
+{
+    if (a->argv)
+    {
+        return print_argv((const char **)a->argv, gc, flags);
+    }
+    else
+    {
+        return "";
+    }
+}
+
+void
+argv_msg(const int msglev, const struct argv *a)
+{
+    struct gc_arena gc = gc_new();
+    msg(msglev, "%s", argv_str(a, &gc, 0));
+    gc_free(&gc);
+}
+
+void
+argv_msg_prefix(const int msglev, const struct argv *a, const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+    msg(msglev, "%s: %s", prefix, argv_str(a, &gc, 0));
+    gc_free(&gc);
+}
+
+static void
+argv_printf_arglist(struct argv *a, const char *format, va_list arglist)
+{
+    char *term;
+    const char *f = format;
+
+    argv_extend(a, 1); /* ensure trailing NULL */
+
+    while ((term = argv_term(&f)) != NULL)
+    {
+        if (term[0] == '%')
+        {
+            if (!strcmp(term, "%s"))
+            {
+                char *s = va_arg(arglist, char *);
+                if (!s)
+                {
+                    s = "";
+                }
+                argv_append(a, string_alloc(s, NULL));
+            }
+            else if (!strcmp(term, "%d"))
+            {
+                char numstr[64];
+                openvpn_snprintf(numstr, sizeof(numstr), "%d", va_arg(arglist, int));
+                argv_append(a, string_alloc(numstr, NULL));
+            }
+            else if (!strcmp(term, "%u"))
+            {
+                char numstr[64];
+                openvpn_snprintf(numstr, sizeof(numstr), "%u", va_arg(arglist, unsigned int));
+                argv_append(a, string_alloc(numstr, NULL));
+            }
+            else if (!strcmp(term, "%lu"))
+            {
+                char numstr[64];
+                openvpn_snprintf(numstr, sizeof(numstr), "%lu",
+                                 va_arg(arglist, unsigned long));
+                argv_append(a, string_alloc(numstr, NULL));
+            }
+            else if (!strcmp(term, "%s/%d"))
+            {
+                char numstr[64];
+                char *s = va_arg(arglist, char *);
+
+                if (!s)
+                {
+                    s = "";
+                }
+
+                openvpn_snprintf(numstr, sizeof(numstr), "%d", va_arg(arglist, int));
+
+                {
+                    const size_t len = strlen(s) + strlen(numstr) + 2;
+                    char *combined = (char *) malloc(len);
+                    check_malloc_return(combined);
+
+                    strcpy(combined, s);
+                    strcat(combined, "/");
+                    strcat(combined, numstr);
+                    argv_append(a, combined);
+                }
+            }
+            else if (!strcmp(term, "%s%sc"))
+            {
+                char *s1 = va_arg(arglist, char *);
+                char *s2 = va_arg(arglist, char *);
+                char *combined;
+
+                if (!s1)
+                {
+                    s1 = "";
+                }
+                if (!s2)
+                {
+                    s2 = "";
+                }
+                combined = (char *) malloc(strlen(s1) + strlen(s2) + 1);
+                check_malloc_return(combined);
+                strcpy(combined, s1);
+                strcat(combined, s2);
+                argv_append(a, combined);
+            }
+            else
+            {
+                ASSERT(0);
+            }
+            free(term);
+        }
+        else
+        {
+            argv_append(a, term);
+        }
+    }
+}
+
+void
+argv_printf(struct argv *a, const char *format, ...)
+{
+    va_list arglist;
+    argv_reset(a);
+    va_start(arglist, format);
+    argv_printf_arglist(a, format, arglist);
+    va_end(arglist);
+}
+
+void
+argv_printf_cat(struct argv *a, const char *format, ...)
+{
+    va_list arglist;
+    va_start(arglist, format);
+    argv_printf_arglist(a, format, arglist);
+    va_end(arglist);
+}
+
+void
+argv_parse_cmd(struct argv *a, const char *s)
+{
+    int nparms;
+    char *parms[MAX_PARMS + 1];
+    struct gc_arena gc = gc_new();
+
+    argv_reset(a);
+    argv_extend(a, 1); /* ensure trailing NULL */
+
+    nparms = parse_line(s, parms, MAX_PARMS, "SCRIPT-ARGV", 0, D_ARGV_PARSE_CMD, &gc);
+    if (nparms)
+    {
+        int i;
+        for (i = 0; i < nparms; ++i)
+        {
+            argv_append(a, string_alloc(parms[i], NULL));
+        }
+    }
+    else
+    {
+        argv_append(a, string_alloc(s, NULL));
+    }
+
+    gc_free(&gc);
+}
diff --git a/src/openvpn/argv.h b/src/openvpn/argv.h
new file mode 100644
index 0000000..9d9f387
--- /dev/null
+++ b/src/openvpn/argv.h
@@ -0,0 +1,75 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ *
+ *  A printf-like function (that only recognizes a subset of standard printf
+ *  format operators) that prints arguments to an argv list instead
+ *  of a standard string.  This is used to build up argv arrays for passing
+ *  to execve.
+ */
+
+#ifndef ARGV_H
+#define ARGV_H
+
+#include "buffer.h"
+
+struct argv {
+    size_t capacity;
+    size_t argc;
+    char **argv;
+};
+
+struct argv argv_new(void);
+
+void argv_reset(struct argv *a);
+
+const char *argv_str(const struct argv *a, struct gc_arena *gc, const unsigned int flags);
+
+struct argv argv_insert_head(const struct argv *a, const char *head);
+
+void argv_msg(const int msglev, const struct argv *a);
+
+void argv_msg_prefix(const int msglev, const struct argv *a, const char *prefix);
+
+void argv_parse_cmd(struct argv *a, const char *s);
+
+void argv_printf(struct argv *a, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 2, 3)))
+#else
+__attribute__ ((format(__printf__, 2, 3)))
+#endif
+#endif
+;
+
+void argv_printf_cat(struct argv *a, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 2, 3)))
+#else
+__attribute__ ((format(__printf__, 2, 3)))
+#endif
+#endif
+;
+
+#endif /* ifndef ARGV_H */
diff --git a/src/openvpn/base64.c b/src/openvpn/base64.c
new file mode 100644
index 0000000..0ac65e9
--- /dev/null
+++ b/src/openvpn/base64.c
@@ -0,0 +1,202 @@
+/*
+ * Copyright (c) 1995-2001 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "base64.h"
+
+#include "memdbg.h"
+
+static char base64_chars[] =
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+/*
+ * base64 encode input data of length size to malloced
+ * buffer which is returned as *str.  Returns string
+ * length of *str.
+ */
+int
+openvpn_base64_encode(const void *data, int size, char **str)
+{
+    char *s, *p;
+    int i;
+    int c;
+    const unsigned char *q;
+
+    if (size < 0)
+    {
+        return -1;
+    }
+    p = s = (char *) malloc(size * 4 / 3 + 4);
+    if (p == NULL)
+    {
+        return -1;
+    }
+    q = (const unsigned char *) data;
+    i = 0;
+    for (i = 0; i < size; )
+    {
+        c = q[i++];
+        c *= 256;
+        if (i < size)
+        {
+            c += q[i];
+        }
+        i++;
+        c *= 256;
+        if (i < size)
+        {
+            c += q[i];
+        }
+        i++;
+        p[0] = base64_chars[(c & 0x00fc0000) >> 18];
+        p[1] = base64_chars[(c & 0x0003f000) >> 12];
+        p[2] = base64_chars[(c & 0x00000fc0) >> 6];
+        p[3] = base64_chars[(c & 0x0000003f) >> 0];
+        if (i > size)
+        {
+            p[3] = '=';
+        }
+        if (i > size + 1)
+        {
+            p[2] = '=';
+        }
+        p += 4;
+    }
+    *p = 0;
+    *str = s;
+    return strlen(s);
+}
+
+static int
+pos(char c)
+{
+    char *p;
+    for (p = base64_chars; *p; p++)
+    {
+        if (*p == c)
+        {
+            return p - base64_chars;
+        }
+    }
+    return -1;
+}
+
+#define DECODE_ERROR 0xffffffff
+
+static unsigned int
+token_decode(const char *token)
+{
+    int i;
+    unsigned int val = 0;
+    int marker = 0;
+    if (!token[0] || !token[1] || !token[2] || !token[3])
+    {
+        return DECODE_ERROR;
+    }
+    for (i = 0; i < 4; i++)
+    {
+        val *= 64;
+        if (token[i] == '=')
+        {
+            marker++;
+        }
+        else if (marker > 0)
+        {
+            return DECODE_ERROR;
+        }
+        else
+        {
+            val += pos(token[i]);
+        }
+    }
+    if (marker > 2)
+    {
+        return DECODE_ERROR;
+    }
+    return (marker << 24) | val;
+}
+/*
+ * Decode base64 str, outputting data to buffer
+ * at data of length size.  Return length of
+ * decoded data written or -1 on error or overflow.
+ */
+int
+openvpn_base64_decode(const char *str, void *data, int size)
+{
+    const char *p;
+    unsigned char *q;
+    unsigned char *e = NULL;
+
+    q = data;
+    if (size >= 0)
+    {
+        e = q + size;
+    }
+    for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4)
+    {
+        unsigned int val = token_decode(p);
+        unsigned int marker = (val >> 24) & 0xff;
+        if (val == DECODE_ERROR)
+        {
+            return -1;
+        }
+        if (e && q >= e)
+        {
+            return -1;
+        }
+        *q++ = (val >> 16) & 0xff;
+        if (marker < 2)
+        {
+            if (e && q >= e)
+            {
+                return -1;
+            }
+            *q++ = (val >> 8) & 0xff;
+        }
+        if (marker < 1)
+        {
+            if (e && q >= e)
+            {
+                return -1;
+            }
+            *q++ = val & 0xff;
+        }
+    }
+    return q - (unsigned char *) data;
+}
diff --git a/src/openvpn/base64.h b/src/openvpn/base64.h
new file mode 100644
index 0000000..5679bc9
--- /dev/null
+++ b/src/openvpn/base64.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright (c) 1995, 1996, 1997 Kungliga Tekniska Högskolan
+ * (Royal Institute of Technology, Stockholm, Sweden).
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * 3. Neither the name of the Institute nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _BASE64_H_
+#define _BASE64_H_
+
+int openvpn_base64_encode(const void *data, int size, char **str);
+
+int openvpn_base64_decode(const char *str, void *data, int size);
+
+#endif
diff --git a/src/openvpn/basic.h b/src/openvpn/basic.h
new file mode 100644
index 0000000..eb9f211
--- /dev/null
+++ b/src/openvpn/basic.h
@@ -0,0 +1,37 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef BASIC_H
+#define BASIC_H
+
+#define BOOL_CAST(x) ((x) ? (true) : (false))
+
+/* size of an array */
+#define SIZE(x) (sizeof(x)/sizeof(x[0]))
+
+/* clear an object (may be optimized away, use secure_memzero() to erase secrets) */
+#define CLEAR(x) memset(&(x), 0, sizeof(x))
+
+#define IPV4_NETMASK_HOST 0xffffffffU
+
+#endif
diff --git a/src/openvpn/block_dns.c b/src/openvpn/block_dns.c
new file mode 100644
index 0000000..889d6bb
--- /dev/null
+++ b/src/openvpn/block_dns.c
@@ -0,0 +1,431 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *                2015-2016  <iam@valdikss.org.ru>
+ *                2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+#ifdef HAVE_CONFIG_VERSION_H
+#include "config-version.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef _WIN32
+
+#include <fwpmu.h>
+#include <initguid.h>
+#include <fwpmtypes.h>
+#include <winsock2.h>
+#include <ws2ipdef.h>
+#include <iphlpapi.h>
+#include "block_dns.h"
+
+/*
+ * WFP-related defines and GUIDs not in mingw32
+ */
+
+#ifndef FWPM_SESSION_FLAG_DYNAMIC
+#define FWPM_SESSION_FLAG_DYNAMIC 0x00000001
+#endif
+
+/* c38d57d1-05a7-4c33-904f-7fbceee60e82 */
+DEFINE_GUID(
+    FWPM_LAYER_ALE_AUTH_CONNECT_V4,
+    0xc38d57d1,
+    0x05a7,
+    0x4c33,
+    0x90, 0x4f, 0x7f, 0xbc, 0xee, 0xe6, 0x0e, 0x82
+    );
+
+/* 4a72393b-319f-44bc-84c3-ba54dcb3b6b4 */
+DEFINE_GUID(
+    FWPM_LAYER_ALE_AUTH_CONNECT_V6,
+    0x4a72393b,
+    0x319f,
+    0x44bc,
+    0x84, 0xc3, 0xba, 0x54, 0xdc, 0xb3, 0xb6, 0xb4
+    );
+
+/* d78e1e87-8644-4ea5-9437-d809ecefc971 */
+DEFINE_GUID(
+    FWPM_CONDITION_ALE_APP_ID,
+    0xd78e1e87,
+    0x8644,
+    0x4ea5,
+    0x94, 0x37, 0xd8, 0x09, 0xec, 0xef, 0xc9, 0x71
+    );
+
+/* c35a604d-d22b-4e1a-91b4-68f674ee674b */
+DEFINE_GUID(
+    FWPM_CONDITION_IP_REMOTE_PORT,
+    0xc35a604d,
+    0xd22b,
+    0x4e1a,
+    0x91, 0xb4, 0x68, 0xf6, 0x74, 0xee, 0x67, 0x4b
+    );
+
+/* 4cd62a49-59c3-4969-b7f3-bda5d32890a4 */
+DEFINE_GUID(
+    FWPM_CONDITION_IP_LOCAL_INTERFACE,
+    0x4cd62a49,
+    0x59c3,
+    0x4969,
+    0xb7, 0xf3, 0xbd, 0xa5, 0xd3, 0x28, 0x90, 0xa4
+    );
+
+/* UUID of WFP sublayer used by all instances of openvpn
+ * 2f660d7e-6a37-11e6-a181-001e8c6e04a2 */
+DEFINE_GUID(
+    OPENVPN_BLOCK_OUTSIDE_DNS_SUBLAYER,
+    0x2f660d7e,
+    0x6a37,
+    0x11e6,
+    0xa1, 0x81, 0x00, 0x1e, 0x8c, 0x6e, 0x04, 0xa2
+    );
+
+static WCHAR *FIREWALL_NAME = L"OpenVPN";
+
+VOID NETIOAPI_API_
+InitializeIpInterfaceEntry(PMIB_IPINTERFACE_ROW Row);
+
+/*
+ * Default msg handler does nothing
+ */
+static inline void
+default_msg_handler(DWORD err, const char *msg)
+{
+    return;
+}
+
+#define CHECK_ERROR(err, msg) \
+    if (err) { msg_handler(err, msg); goto out; }
+
+/*
+ * Add a persistent sublayer with specified uuid.
+ */
+static DWORD
+add_sublayer(GUID uuid)
+{
+    FWPM_SESSION0 session;
+    HANDLE engine = NULL;
+    DWORD err = 0;
+    FWPM_SUBLAYER0 sublayer;
+
+    memset(&session, 0, sizeof(session));
+    memset(&sublayer, 0, sizeof(sublayer));
+
+    err = FwpmEngineOpen0(NULL, RPC_C_AUTHN_WINNT, NULL, &session, &engine);
+    if (err != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    sublayer.subLayerKey = uuid;
+    sublayer.displayData.name = FIREWALL_NAME;
+    sublayer.displayData.description = FIREWALL_NAME;
+    sublayer.flags = 0;
+    sublayer.weight = 0x100;
+
+    /* Add sublayer to the session */
+    err = FwpmSubLayerAdd0(engine, &sublayer, NULL);
+
+out:
+    if (engine)
+    {
+        FwpmEngineClose0(engine);
+    }
+    return err;
+}
+
+/*
+ * Block outgoing port 53 traffic except for
+ * (i) adapter with the specified index
+ * OR
+ * (ii) processes with the specified executable path
+ * The firewall filters added here are automatically removed when the process exits or
+ * on calling delete_block_dns_filters().
+ * Arguments:
+ *   engine_handle : On successful return contains the handle for a newly opened fwp session
+ *                   in which the filters are added.
+ *                   May be closed by passing to delete_block_dns_filters to remove the filters.
+ *   index         : The index of adapter for which traffic is permitted.
+ *   exe_path      : Path of executable for which traffic is permitted.
+ *   msg_handler   : An optional callback function for error reporting.
+ * Returns 0 on success, a non-zero status code of the last failed action on failure.
+ */
+
+DWORD
+add_block_dns_filters(HANDLE *engine_handle,
+                      int index,
+                      const WCHAR *exe_path,
+                      block_dns_msg_handler_t msg_handler
+                      )
+{
+    FWPM_SESSION0 session = {0};
+    FWPM_SUBLAYER0 *sublayer_ptr = NULL;
+    NET_LUID tapluid;
+    UINT64 filterid;
+    FWP_BYTE_BLOB *openvpnblob = NULL;
+    FWPM_FILTER0 Filter = {0};
+    FWPM_FILTER_CONDITION0 Condition[2] = {0};
+    DWORD err = 0;
+
+    if (!msg_handler)
+    {
+        msg_handler = default_msg_handler;
+    }
+
+    /* Add temporary filters which don't survive reboots or crashes. */
+    session.flags = FWPM_SESSION_FLAG_DYNAMIC;
+
+    *engine_handle = NULL;
+
+    err = FwpmEngineOpen0(NULL, RPC_C_AUTHN_WINNT, NULL, &session, engine_handle);
+    CHECK_ERROR(err, "FwpEngineOpen: open fwp session failed");
+    msg_handler(0, "Block_DNS: WFP engine opened");
+
+    /* Check sublayer exists and add one if it does not. */
+    if (FwpmSubLayerGetByKey0(*engine_handle, &OPENVPN_BLOCK_OUTSIDE_DNS_SUBLAYER, &sublayer_ptr)
+        == ERROR_SUCCESS)
+    {
+        msg_handler(0, "Block_DNS: Using existing sublayer");
+        FwpmFreeMemory0((void **)&sublayer_ptr);
+    }
+    else
+    {  /* Add a new sublayer -- as another process may add it in the meantime,
+        * do not treat "already exists" as an error */
+        err = add_sublayer(OPENVPN_BLOCK_OUTSIDE_DNS_SUBLAYER);
+
+        if (err == FWP_E_ALREADY_EXISTS || err == ERROR_SUCCESS)
+        {
+            msg_handler(0, "Block_DNS: Added a persistent sublayer with pre-defined UUID");
+        }
+        else
+        {
+            CHECK_ERROR(err, "add_sublayer: failed to add persistent sublayer");
+        }
+    }
+
+    err = ConvertInterfaceIndexToLuid(index, &tapluid);
+    CHECK_ERROR(err, "Convert interface index to luid failed");
+
+    err = FwpmGetAppIdFromFileName0(exe_path, &openvpnblob);
+    CHECK_ERROR(err, "Get byte blob for openvpn executable name failed");
+
+    /* Prepare filter. */
+    Filter.subLayerKey = OPENVPN_BLOCK_OUTSIDE_DNS_SUBLAYER;
+    Filter.displayData.name = FIREWALL_NAME;
+    Filter.weight.type = FWP_UINT8;
+    Filter.weight.uint8 = 0xF;
+    Filter.filterCondition = Condition;
+    Filter.numFilterConditions = 2;
+
+    /* First filter. Permit IPv4 DNS queries from OpenVPN itself. */
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V4;
+    Filter.action.type = FWP_ACTION_PERMIT;
+
+    Condition[0].fieldKey = FWPM_CONDITION_IP_REMOTE_PORT;
+    Condition[0].matchType = FWP_MATCH_EQUAL;
+    Condition[0].conditionValue.type = FWP_UINT16;
+    Condition[0].conditionValue.uint16 = 53;
+
+    Condition[1].fieldKey = FWPM_CONDITION_ALE_APP_ID;
+    Condition[1].matchType = FWP_MATCH_EQUAL;
+    Condition[1].conditionValue.type = FWP_BYTE_BLOB_TYPE;
+    Condition[1].conditionValue.byteBlob = openvpnblob;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to permit IPv4 port 53 traffic from OpenVPN failed");
+
+    /* Second filter. Permit IPv6 DNS queries from OpenVPN itself. */
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V6;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to permit IPv6 port 53 traffic from OpenVPN failed");
+
+    msg_handler(0, "Block_DNS: Added permit filters for exe_path");
+
+    /* Third filter. Block all IPv4 DNS queries. */
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V4;
+    Filter.action.type = FWP_ACTION_BLOCK;
+    Filter.weight.type = FWP_EMPTY;
+    Filter.numFilterConditions = 1;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to block IPv4 DNS traffic failed");
+
+    /* Forth filter. Block all IPv6 DNS queries. */
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V6;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to block IPv6 DNS traffic failed");
+
+    msg_handler(0, "Block_DNS: Added block filters for all interfaces");
+
+    /* Fifth filter. Permit IPv4 DNS queries from TAP.
+     * Use a non-zero weight so that the permit filters get higher priority
+     * over the block filter added with automatic weighting */
+
+    Filter.weight.type = FWP_UINT8;
+    Filter.weight.uint8 = 0xE;
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V4;
+    Filter.action.type = FWP_ACTION_PERMIT;
+    Filter.numFilterConditions = 2;
+
+    Condition[1].fieldKey = FWPM_CONDITION_IP_LOCAL_INTERFACE;
+    Condition[1].matchType = FWP_MATCH_EQUAL;
+    Condition[1].conditionValue.type = FWP_UINT64;
+    Condition[1].conditionValue.uint64 = &tapluid.Value;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to permit IPv4 DNS traffic through TAP failed");
+
+    /* Sixth filter. Permit IPv6 DNS queries from TAP.
+     * Use same weight as IPv4 filter */
+    Filter.layerKey = FWPM_LAYER_ALE_AUTH_CONNECT_V6;
+
+    err = FwpmFilterAdd0(*engine_handle, &Filter, NULL, &filterid);
+    CHECK_ERROR(err, "Add filter to permit IPv6 DNS traffic through TAP failed");
+
+    msg_handler(0, "Block_DNS: Added permit filters for TAP interface");
+
+out:
+
+    if (openvpnblob)
+    {
+        FwpmFreeMemory0((void **)&openvpnblob);
+    }
+
+    if (err && *engine_handle)
+    {
+        FwpmEngineClose0(*engine_handle);
+        *engine_handle = NULL;
+    }
+
+    return err;
+}
+
+DWORD
+delete_block_dns_filters(HANDLE engine_handle)
+{
+    DWORD err = 0;
+    /*
+     * For dynamic sessions closing the engine removes all filters added in the session
+     */
+    if (engine_handle)
+    {
+        err = FwpmEngineClose0(engine_handle);
+    }
+    return err;
+}
+
+/*
+ * Return interface metric value for the specified interface index.
+ *
+ * Arguments:
+ *   index         : The index of TAP adapter.
+ *   family        : Address family (AF_INET for IPv4 and AF_INET6 for IPv6).
+ *   is_auto       : On return set to true if automatic metric is in use.
+ *                   Unused if NULL.
+ *
+ * Returns positive metric value or -1 on error.
+ */
+int
+get_interface_metric(const NET_IFINDEX index, const ADDRESS_FAMILY family, int *is_auto)
+{
+    DWORD err = 0;
+    MIB_IPINTERFACE_ROW ipiface;
+    InitializeIpInterfaceEntry(&ipiface);
+    ipiface.Family = family;
+    ipiface.InterfaceIndex = index;
+
+    if (is_auto)
+    {
+        *is_auto = 0;
+    }
+    err = GetIpInterfaceEntry(&ipiface);
+
+    /* On Windows metric is never > INT_MAX so return value of int is ok.
+     * But we check for overflow nevertheless.
+     */
+    if (err == NO_ERROR && ipiface.Metric <= INT_MAX)
+    {
+        if (is_auto)
+        {
+            *is_auto = ipiface.UseAutomaticMetric;
+        }
+        return (int)ipiface.Metric;
+    }
+    return -1;
+}
+
+/*
+ * Sets interface metric value for specified interface index.
+ *
+ * Arguments:
+ *   index         : The index of TAP adapter.
+ *   family        : Address family (AF_INET for IPv4 and AF_INET6 for IPv6).
+ *   metric        : Metric value. 0 for automatic metric.
+ * Returns 0 on success, a non-zero status code of the last failed action on failure.
+ */
+
+DWORD
+set_interface_metric(const NET_IFINDEX index, const ADDRESS_FAMILY family,
+                     const ULONG metric)
+{
+    DWORD err = 0;
+    MIB_IPINTERFACE_ROW ipiface;
+    InitializeIpInterfaceEntry(&ipiface);
+    ipiface.Family = family;
+    ipiface.InterfaceIndex = index;
+    err = GetIpInterfaceEntry(&ipiface);
+    if (err == NO_ERROR)
+    {
+        if (family == AF_INET)
+        {
+            /* required for IPv4 as per MSDN */
+            ipiface.SitePrefixLength = 0;
+        }
+        ipiface.Metric = metric;
+        if (metric == 0)
+        {
+            ipiface.UseAutomaticMetric = TRUE;
+        }
+        else
+        {
+            ipiface.UseAutomaticMetric = FALSE;
+        }
+        err = SetIpInterfaceEntry(&ipiface);
+        if (err == NO_ERROR)
+        {
+            return 0;
+        }
+    }
+    return err;
+}
+
+#endif /* ifdef _WIN32 */
diff --git a/src/openvpn/block_dns.h b/src/openvpn/block_dns.h
new file mode 100644
index 0000000..50b383f
--- /dev/null
+++ b/src/openvpn/block_dns.h
@@ -0,0 +1,69 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef _WIN32
+
+#ifndef OPENVPN_BLOCK_DNS_H
+#define OPENVPN_BLOCK_DNS_H
+
+/* Any value less than 5 should work fine. 3 is chosen without any real reason. */
+#define BLOCK_DNS_IFACE_METRIC 3
+
+typedef void (*block_dns_msg_handler_t) (DWORD err, const char *msg);
+
+DWORD
+delete_block_dns_filters(HANDLE engine);
+
+DWORD
+add_block_dns_filters(HANDLE *engine, int iface_index, const WCHAR *exe_path,
+                      block_dns_msg_handler_t msg_handler_callback);
+
+/**
+ * Return interface metric value for the specified interface index.
+ *
+ * @param index         The index of TAP adapter.
+ * @param family        Address family (AF_INET for IPv4 and AF_INET6 for IPv6).
+ * @param is_auto       On return set to true if automatic metric is in use.
+ *                      Unused if NULL.
+ *
+ * @return positive interface metric on success or -1 on error
+ */
+int
+get_interface_metric(const NET_IFINDEX index, const ADDRESS_FAMILY family, int *is_auto);
+
+/**
+ * Sets interface metric value for specified interface index.
+ *
+ * @param index The index of TAP adapter
+ * @param family Address family (AF_INET for IPv4 and AF_INET6 for IPv6)
+ * @param metric Metric value. 0 for automatic metric
+ *
+ * @return 0 on success, a non-zero status code of the last failed action on failure.
+ */
+
+DWORD
+set_interface_metric(const NET_IFINDEX index, const ADDRESS_FAMILY family,
+                     const ULONG metric);
+
+#endif
+#endif
diff --git a/src/openvpn/buffer.c b/src/openvpn/buffer.c
new file mode 100644
index 0000000..f9c76b1
--- /dev/null
+++ b/src/openvpn/buffer.c
@@ -0,0 +1,1337 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "buffer.h"
+#include "error.h"
+#include "mtu.h"
+#include "misc.h"
+
+#include "memdbg.h"
+
+size_t
+array_mult_safe(const size_t m1, const size_t m2, const size_t extra)
+{
+    const size_t limit = 0xFFFFFFFF;
+    unsigned long long res = (unsigned long long)m1 * (unsigned long long)m2 + (unsigned long long)extra;
+    if (unlikely(m1 > limit) || unlikely(m2 > limit) || unlikely(extra > limit) || unlikely(res > (unsigned long long)limit))
+    {
+        msg(M_FATAL, "attemped allocation of excessively large array");
+    }
+    return (size_t) res;
+}
+
+void
+buf_size_error(const size_t size)
+{
+    msg(M_FATAL, "fatal buffer size error, size=%lu", (unsigned long)size);
+}
+
+struct buffer
+#ifdef DMALLOC
+alloc_buf_debug(size_t size, const char *file, int line)
+#else
+alloc_buf(size_t size)
+#endif
+{
+    struct buffer buf;
+
+    if (!buf_size_valid(size))
+    {
+        buf_size_error(size);
+    }
+    buf.capacity = (int)size;
+    buf.offset = 0;
+    buf.len = 0;
+#ifdef DMALLOC
+    buf.data = openvpn_dmalloc(file, line, size);
+#else
+    buf.data = calloc(1, size);
+#endif
+    check_malloc_return(buf.data);
+
+    return buf;
+}
+
+struct buffer
+#ifdef DMALLOC
+alloc_buf_gc_debug(size_t size, struct gc_arena *gc, const char *file, int line)
+#else
+alloc_buf_gc(size_t size, struct gc_arena *gc)
+#endif
+{
+    struct buffer buf;
+    if (!buf_size_valid(size))
+    {
+        buf_size_error(size);
+    }
+    buf.capacity = (int)size;
+    buf.offset = 0;
+    buf.len = 0;
+#ifdef DMALLOC
+    buf.data = (uint8_t *) gc_malloc_debug(size, false, gc, file, line);
+#else
+    buf.data = (uint8_t *) gc_malloc(size, false, gc);
+#endif
+    if (size)
+    {
+        *buf.data = 0;
+    }
+    return buf;
+}
+
+struct buffer
+#ifdef DMALLOC
+clone_buf_debug(const struct buffer *buf, const char *file, int line)
+#else
+clone_buf(const struct buffer *buf)
+#endif
+{
+    struct buffer ret;
+    ret.capacity = buf->capacity;
+    ret.offset = buf->offset;
+    ret.len = buf->len;
+#ifdef DMALLOC
+    ret.data = (uint8_t *) openvpn_dmalloc(file, line, buf->capacity);
+#else
+    ret.data = (uint8_t *) malloc(buf->capacity);
+#endif
+    check_malloc_return(ret.data);
+    memcpy(BPTR(&ret), BPTR(buf), BLEN(buf));
+    return ret;
+}
+
+#ifdef BUF_INIT_TRACKING
+
+bool
+buf_init_debug(struct buffer *buf, int offset, const char *file, int line)
+{
+    buf->debug_file = file;
+    buf->debug_line = line;
+    return buf_init_dowork(buf, offset);
+}
+
+static inline int
+buf_debug_line(const struct buffer *buf)
+{
+    return buf->debug_line;
+}
+
+static const char *
+buf_debug_file(const struct buffer *buf)
+{
+    return buf->debug_file;
+}
+
+#else  /* ifdef BUF_INIT_TRACKING */
+
+#define buf_debug_line(buf) 0
+#define buf_debug_file(buf) "[UNDEF]"
+
+#endif /* ifdef BUF_INIT_TRACKING */
+
+void
+buf_clear(struct buffer *buf)
+{
+    if (buf->capacity > 0)
+    {
+        secure_memzero(buf->data, buf->capacity);
+    }
+    buf->len = 0;
+    buf->offset = 0;
+}
+
+bool
+buf_assign(struct buffer *dest, const struct buffer *src)
+{
+    if (!buf_init(dest, src->offset))
+    {
+        return false;
+    }
+    return buf_write(dest, BPTR(src), BLEN(src));
+}
+
+struct buffer
+clear_buf(void)
+{
+    struct buffer buf;
+    CLEAR(buf);
+    return buf;
+}
+
+void
+free_buf(struct buffer *buf)
+{
+    if (buf->data)
+    {
+        free(buf->data);
+    }
+    CLEAR(*buf);
+}
+
+/*
+ * Return a buffer for write that is a subset of another buffer
+ */
+struct buffer
+buf_sub(struct buffer *buf, int size, bool prepend)
+{
+    struct buffer ret;
+    uint8_t *data;
+
+    CLEAR(ret);
+    data = prepend ? buf_prepend(buf, size) : buf_write_alloc(buf, size);
+    if (data)
+    {
+        ret.capacity = size;
+        ret.data = data;
+    }
+    return ret;
+}
+
+/*
+ * printf append to a buffer with overflow check
+ */
+bool
+buf_printf(struct buffer *buf, const char *format, ...)
+{
+    int ret = false;
+    if (buf_defined(buf))
+    {
+        va_list arglist;
+        uint8_t *ptr = BEND(buf);
+        int cap = buf_forward_capacity(buf);
+
+        if (cap > 0)
+        {
+            int stat;
+            va_start(arglist, format);
+            stat = vsnprintf((char *)ptr, cap, format, arglist);
+            va_end(arglist);
+            *(buf->data + buf->capacity - 1) = 0; /* windows vsnprintf needs this */
+            buf->len += (int) strlen((char *)ptr);
+            if (stat >= 0 && stat < cap)
+            {
+                ret = true;
+            }
+        }
+    }
+    return ret;
+}
+
+bool
+buf_puts(struct buffer *buf, const char *str)
+{
+    int ret = false;
+    uint8_t *ptr = BEND(buf);
+    int cap = buf_forward_capacity(buf);
+    if (cap > 0)
+    {
+        strncpynt((char *)ptr,str, cap);
+        *(buf->data + buf->capacity - 1) = 0; /* windows vsnprintf needs this */
+        buf->len += (int) strlen((char *)ptr);
+        ret = true;
+    }
+    return ret;
+}
+
+
+/*
+ * This is necessary due to certain buggy implementations of snprintf,
+ * that don't guarantee null termination for size > 0.
+ *
+ * Return false on overflow.
+ *
+ * This functionality is duplicated in src/openvpnserv/common.c
+ * Any modifications here should be done to the other place as well.
+ */
+
+bool
+openvpn_snprintf(char *str, size_t size, const char *format, ...)
+{
+    va_list arglist;
+    int len = -1;
+    if (size > 0)
+    {
+        va_start(arglist, format);
+        len = vsnprintf(str, size, format, arglist);
+        va_end(arglist);
+        str[size - 1] = 0;
+    }
+    return (len >= 0 && len < size);
+}
+
+/*
+ * write a string to the end of a buffer that was
+ * truncated by buf_printf
+ */
+void
+buf_catrunc(struct buffer *buf, const char *str)
+{
+    if (buf_forward_capacity(buf) <= 1)
+    {
+        int len = (int) strlen(str) + 1;
+        if (len < buf_forward_capacity_total(buf))
+        {
+            strncpynt((char *)(buf->data + buf->capacity - len), str, len);
+        }
+    }
+}
+
+/*
+ * convert a multi-line output to one line
+ */
+void
+convert_to_one_line(struct buffer *buf)
+{
+    uint8_t *cp = BPTR(buf);
+    int len = BLEN(buf);
+    while (len--)
+    {
+        if (*cp == '\n')
+        {
+            *cp = '|';
+        }
+        ++cp;
+    }
+}
+
+/* NOTE: requires that string be null terminated */
+void
+buf_write_string_file(const struct buffer *buf, const char *filename, int fd)
+{
+    const int len = strlen((char *) BPTR(buf));
+    const int size = write(fd, BPTR(buf), len);
+    if (size != len)
+    {
+        msg(M_ERR, "Write error on file '%s'", filename);
+    }
+}
+
+/*
+ * Garbage collection
+ */
+
+void *
+#ifdef DMALLOC
+gc_malloc_debug(size_t size, bool clear, struct gc_arena *a, const char *file, int line)
+#else
+gc_malloc(size_t size, bool clear, struct gc_arena *a)
+#endif
+{
+    void *ret;
+    if (a)
+    {
+        struct gc_entry *e;
+#ifdef DMALLOC
+        e = (struct gc_entry *) openvpn_dmalloc(file, line, size + sizeof(struct gc_entry));
+#else
+        e = (struct gc_entry *) malloc(size + sizeof(struct gc_entry));
+#endif
+        check_malloc_return(e);
+        ret = (char *) e + sizeof(struct gc_entry);
+        e->next = a->list;
+        a->list = e;
+    }
+    else
+    {
+#ifdef DMALLOC
+        ret = openvpn_dmalloc(file, line, size);
+#else
+        ret = malloc(size);
+#endif
+        check_malloc_return(ret);
+    }
+#ifndef ZERO_BUFFER_ON_ALLOC
+    if (clear)
+#endif
+    memset(ret, 0, size);
+    return ret;
+}
+
+void
+x_gc_free(struct gc_arena *a)
+{
+    struct gc_entry *e;
+    e = a->list;
+    a->list = NULL;
+
+    while (e != NULL)
+    {
+        struct gc_entry *next = e->next;
+        free(e);
+        e = next;
+    }
+}
+
+/*
+ * Functions to handle special objects in gc_entries
+ */
+
+void
+x_gc_freespecial(struct gc_arena *a)
+{
+    struct gc_entry_special *e;
+    e = a->list_special;
+    a->list_special = NULL;
+
+    while (e != NULL)
+    {
+        struct gc_entry_special *next = e->next;
+        e->free_fnc(e->addr);
+        free(e);
+        e = next;
+    }
+}
+
+void
+gc_addspecial(void *addr, void(free_function)(void *), struct gc_arena *a)
+{
+    ASSERT(a);
+    struct gc_entry_special *e;
+#ifdef DMALLOC
+    e = (struct gc_entry_special *) openvpn_dmalloc(file, line, sizeof(struct gc_entry_special));
+#else
+    e = (struct gc_entry_special *) malloc(sizeof(struct gc_entry_special));
+#endif
+    check_malloc_return(e);
+    e->free_fnc = free_function;
+    e->addr = addr;
+
+    e->next = a->list_special;
+    a->list_special = e;
+}
+
+
+/*
+ * Transfer src arena to dest, resetting src to an empty arena.
+ */
+void
+gc_transfer(struct gc_arena *dest, struct gc_arena *src)
+{
+    if (dest && src)
+    {
+        struct gc_entry *e = src->list;
+        if (e)
+        {
+            while (e->next != NULL)
+            {
+                e = e->next;
+            }
+            e->next = dest->list;
+            dest->list = src->list;
+            src->list = NULL;
+        }
+    }
+}
+
+/*
+ * Hex dump -- Output a binary buffer to a hex string and return it.
+ */
+
+char *
+format_hex_ex(const uint8_t *data, int size, int maxoutput,
+              unsigned int space_break_flags, const char *separator,
+              struct gc_arena *gc)
+{
+    const size_t bytes_per_hexblock = space_break_flags & FHE_SPACE_BREAK_MASK;
+    const size_t separator_len = separator ? strlen(separator) : 0;
+    static_assert(INT_MAX <= SIZE_MAX, "Code assumes INT_MAX <= SIZE_MAX");
+    const size_t out_len = maxoutput > 0 ? maxoutput :
+                           ((size * 2) + ((size / bytes_per_hexblock) * separator_len) + 2);
+
+    struct buffer out = alloc_buf_gc(out_len, gc);
+    for (int i = 0; i < size; ++i)
+    {
+        if (separator && i && !(i % bytes_per_hexblock))
+        {
+            buf_printf(&out, "%s", separator);
+        }
+        if (space_break_flags & FHE_CAPS)
+        {
+            buf_printf(&out, "%02X", data[i]);
+        }
+        else
+        {
+            buf_printf(&out, "%02x", data[i]);
+        }
+    }
+    buf_catrunc(&out, "[more...]");
+    return (char *)out.data;
+}
+
+/*
+ * remove specific trailing character
+ */
+
+void
+buf_rmtail(struct buffer *buf, uint8_t remove)
+{
+    uint8_t *cp = BLAST(buf);
+    if (cp && *cp == remove)
+    {
+        *cp = '\0';
+        --buf->len;
+    }
+}
+
+/*
+ * force a null termination even it requires
+ * truncation of the last char.
+ */
+void
+buf_null_terminate(struct buffer *buf)
+{
+    char *last = (char *) BLAST(buf);
+    if (last && *last == '\0') /* already terminated? */
+    {
+        return;
+    }
+
+    if (!buf_safe(buf, 1))   /* make space for trailing null */
+    {
+        buf_inc_len(buf, -1);
+    }
+
+    buf_write_u8(buf, 0);
+}
+
+/*
+ * Remove trailing \r and \n chars and ensure
+ * null termination.
+ */
+void
+buf_chomp(struct buffer *buf)
+{
+    while (true)
+    {
+        char *last = (char *) BLAST(buf);
+        if (!last)
+        {
+            break;
+        }
+        if (char_class(*last, CC_CRLF|CC_NULL))
+        {
+            if (!buf_inc_len(buf, -1))
+            {
+                break;
+            }
+        }
+        else
+        {
+            break;
+        }
+    }
+    buf_null_terminate(buf);
+}
+
+const char *
+skip_leading_whitespace(const char *str)
+{
+    while (*str)
+    {
+        const char c = *str;
+        if (!(c == ' ' || c == '\t'))
+        {
+            break;
+        }
+        ++str;
+    }
+    return str;
+}
+
+/*
+ * like buf_null_terminate, but operate on strings
+ */
+void
+string_null_terminate(char *str, int len, int capacity)
+{
+    ASSERT(len >= 0 && len <= capacity && capacity > 0);
+    if (len < capacity)
+    {
+        *(str + len) = '\0';
+    }
+    else if (len == capacity)
+    {
+        *(str + len - 1) = '\0';
+    }
+}
+
+/*
+ * Remove trailing \r and \n chars.
+ */
+void
+chomp(char *str)
+{
+    rm_trailing_chars(str, "\r\n");
+}
+
+/*
+ * Remove trailing chars
+ */
+void
+rm_trailing_chars(char *str, const char *what_to_delete)
+{
+    bool modified;
+    do
+    {
+        const int len = strlen(str);
+        modified = false;
+        if (len > 0)
+        {
+            char *cp = str + (len - 1);
+            if (strchr(what_to_delete, *cp) != NULL)
+            {
+                *cp = '\0';
+                modified = true;
+            }
+        }
+    } while (modified);
+}
+
+/*
+ * Allocate a string
+ */
+char *
+#ifdef DMALLOC
+string_alloc_debug(const char *str, struct gc_arena *gc, const char *file, int line)
+#else
+string_alloc(const char *str, struct gc_arena *gc)
+#endif
+{
+    if (str)
+    {
+        const int n = strlen(str) + 1;
+        char *ret;
+
+        if (gc)
+        {
+#ifdef DMALLOC
+            ret = (char *) gc_malloc_debug(n, false, gc, file, line);
+#else
+            ret = (char *) gc_malloc(n, false, gc);
+#endif
+        }
+        else
+        {
+            /* If there are no garbage collector available, it's expected
+             * that the caller cleans up afterwards.  This is coherent with the
+             * earlier behaviour when gc_malloc() would be called with gc == NULL
+             */
+#ifdef DMALLOC
+            ret = openvpn_dmalloc(file, line, n);
+            memset(ret, 0, n);
+#else
+            ret = calloc(1, n);
+#endif
+            check_malloc_return(ret);
+        }
+        memcpy(ret, str, n);
+        return ret;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+/*
+ * Erase all characters in a string
+ */
+void
+string_clear(char *str)
+{
+    if (str)
+    {
+        secure_memzero(str, strlen(str));
+    }
+}
+
+/*
+ * Return the length of a string array
+ */
+int
+string_array_len(const char **array)
+{
+    int i = 0;
+    if (array)
+    {
+        while (array[i])
+        {
+            ++i;
+        }
+    }
+    return i;
+}
+
+char *
+print_argv(const char **p, struct gc_arena *gc, const unsigned int flags)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    int i = 0;
+    for (;; )
+    {
+        const char *cp = *p++;
+        if (!cp)
+        {
+            break;
+        }
+        if (i)
+        {
+            buf_printf(&out, " ");
+        }
+        if (flags & PA_BRACKET)
+        {
+            buf_printf(&out, "[%s]", cp);
+        }
+        else
+        {
+            buf_printf(&out, "%s", cp);
+        }
+        ++i;
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Allocate a string inside a buffer
+ */
+struct buffer
+#ifdef DMALLOC
+string_alloc_buf_debug(const char *str, struct gc_arena *gc, const char *file, int line)
+#else
+string_alloc_buf(const char *str, struct gc_arena *gc)
+#endif
+{
+    struct buffer buf;
+
+    ASSERT(str);
+
+#ifdef DMALLOC
+    buf_set_read(&buf, (uint8_t *) string_alloc_debug(str, gc, file, line), strlen(str) + 1);
+#else
+    buf_set_read(&buf, (uint8_t *) string_alloc(str, gc), strlen(str) + 1);
+#endif
+
+    if (buf.len > 0) /* Don't count trailing '\0' as part of length */
+    {
+        --buf.len;
+    }
+
+    return buf;
+}
+
+/*
+ * String comparison
+ */
+
+bool
+buf_string_match_head_str(const struct buffer *src, const char *match)
+{
+    const int size = strlen(match);
+    if (size < 0 || size > src->len)
+    {
+        return false;
+    }
+    return memcmp(BPTR(src), match, size) == 0;
+}
+
+bool
+buf_string_compare_advance(struct buffer *src, const char *match)
+{
+    if (buf_string_match_head_str(src, match))
+    {
+        buf_advance(src, strlen(match));
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+int
+buf_substring_len(const struct buffer *buf, int delim)
+{
+    int i = 0;
+    struct buffer tmp = *buf;
+    int c;
+
+    while ((c = buf_read_u8(&tmp)) >= 0)
+    {
+        ++i;
+        if (c == delim)
+        {
+            return i;
+        }
+    }
+    return -1;
+}
+
+/*
+ * String parsing
+ */
+
+bool
+buf_parse(struct buffer *buf, const int delim, char *line, const int size)
+{
+    bool eol = false;
+    int n = 0;
+    int c;
+
+    ASSERT(size > 0);
+
+    do
+    {
+        c = buf_read_u8(buf);
+        if (c < 0)
+        {
+            eol = true;
+        }
+        if (c <= 0 || c == delim)
+        {
+            c = 0;
+        }
+        if (n >= size)
+        {
+            break;
+        }
+        line[n++] = c;
+    }
+    while (c);
+
+    line[size-1] = '\0';
+    return !(eol && !strlen(line));
+}
+
+/*
+ * Print a string which might be NULL
+ */
+const char *
+np(const char *str)
+{
+    if (str)
+    {
+        return str;
+    }
+    else
+    {
+        return "[NULL]";
+    }
+}
+
+/*
+ * Classify and mutate strings based on character types.
+ */
+
+bool
+char_class(const unsigned char c, const unsigned int flags)
+{
+    if (!flags)
+    {
+        return false;
+    }
+    if (flags & CC_ANY)
+    {
+        return true;
+    }
+
+    if ((flags & CC_NULL) && c == '\0')
+    {
+        return true;
+    }
+
+    if ((flags & CC_ALNUM) && isalnum(c))
+    {
+        return true;
+    }
+    if ((flags & CC_ALPHA) && isalpha(c))
+    {
+        return true;
+    }
+    if ((flags & CC_ASCII) && isascii(c))
+    {
+        return true;
+    }
+    if ((flags & CC_CNTRL) && iscntrl(c))
+    {
+        return true;
+    }
+    if ((flags & CC_DIGIT) && isdigit(c))
+    {
+        return true;
+    }
+    if ((flags & CC_PRINT) && (c >= 32 && c != 127)) /* allow ascii non-control and UTF-8, consider DEL to be a control */
+    {
+        return true;
+    }
+    if ((flags & CC_PUNCT) && ispunct(c))
+    {
+        return true;
+    }
+    if ((flags & CC_SPACE) && isspace(c))
+    {
+        return true;
+    }
+    if ((flags & CC_XDIGIT) && isxdigit(c))
+    {
+        return true;
+    }
+
+    if ((flags & CC_BLANK) && (c == ' ' || c == '\t'))
+    {
+        return true;
+    }
+    if ((flags & CC_NEWLINE) && c == '\n')
+    {
+        return true;
+    }
+    if ((flags & CC_CR) && c == '\r')
+    {
+        return true;
+    }
+
+    if ((flags & CC_BACKSLASH) && c == '\\')
+    {
+        return true;
+    }
+    if ((flags & CC_UNDERBAR) && c == '_')
+    {
+        return true;
+    }
+    if ((flags & CC_DASH) && c == '-')
+    {
+        return true;
+    }
+    if ((flags & CC_DOT) && c == '.')
+    {
+        return true;
+    }
+    if ((flags & CC_COMMA) && c == ',')
+    {
+        return true;
+    }
+    if ((flags & CC_COLON) && c == ':')
+    {
+        return true;
+    }
+    if ((flags & CC_SLASH) && c == '/')
+    {
+        return true;
+    }
+    if ((flags & CC_SINGLE_QUOTE) && c == '\'')
+    {
+        return true;
+    }
+    if ((flags & CC_DOUBLE_QUOTE) && c == '\"')
+    {
+        return true;
+    }
+    if ((flags & CC_REVERSE_QUOTE) && c == '`')
+    {
+        return true;
+    }
+    if ((flags & CC_AT) && c == '@')
+    {
+        return true;
+    }
+    if ((flags & CC_EQUAL) && c == '=')
+    {
+        return true;
+    }
+    if ((flags & CC_LESS_THAN) && c == '<')
+    {
+        return true;
+    }
+    if ((flags & CC_GREATER_THAN) && c == '>')
+    {
+        return true;
+    }
+    if ((flags & CC_PIPE) && c == '|')
+    {
+        return true;
+    }
+    if ((flags & CC_QUESTION_MARK) && c == '?')
+    {
+        return true;
+    }
+    if ((flags & CC_ASTERISK) && c == '*')
+    {
+        return true;
+    }
+
+    return false;
+}
+
+static inline bool
+char_inc_exc(const char c, const unsigned int inclusive, const unsigned int exclusive)
+{
+    return char_class(c, inclusive) && !char_class(c, exclusive);
+}
+
+bool
+string_class(const char *str, const unsigned int inclusive, const unsigned int exclusive)
+{
+    char c;
+    ASSERT(str);
+    while ((c = *str++))
+    {
+        if (!char_inc_exc(c, inclusive, exclusive))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+/*
+ * Modify string in place.
+ * Guaranteed to not increase string length.
+ */
+bool
+string_mod(char *str, const unsigned int inclusive, const unsigned int exclusive, const char replace)
+{
+    const char *in = str;
+    bool ret = true;
+
+    ASSERT(str);
+
+    while (true)
+    {
+        char c = *in++;
+        if (c)
+        {
+            if (!char_inc_exc(c, inclusive, exclusive))
+            {
+                c = replace;
+                ret = false;
+            }
+            if (c)
+            {
+                *str++ = c;
+            }
+        }
+        else
+        {
+            *str = '\0';
+            break;
+        }
+    }
+    return ret;
+}
+
+const char *
+string_mod_const(const char *str,
+                 const unsigned int inclusive,
+                 const unsigned int exclusive,
+                 const char replace,
+                 struct gc_arena *gc)
+{
+    if (str)
+    {
+        char *buf = string_alloc(str, gc);
+        string_mod(buf, inclusive, exclusive, replace);
+        return buf;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+void
+string_replace_leading(char *str, const char match, const char replace)
+{
+    ASSERT(match != '\0');
+    while (*str)
+    {
+        if (*str == match)
+        {
+            *str = replace;
+        }
+        else
+        {
+            break;
+        }
+        ++str;
+    }
+}
+
+#ifdef CHARACTER_CLASS_DEBUG
+
+#define CC_INCLUDE    (CC_PRINT)
+#define CC_EXCLUDE    (0)
+#define CC_REPLACE    ('.')
+
+void
+character_class_debug(void)
+{
+    char buf[256];
+
+    while (fgets(buf, sizeof(buf), stdin) != NULL)
+    {
+        string_mod(buf, CC_INCLUDE, CC_EXCLUDE, CC_REPLACE);
+        printf("%s", buf);
+    }
+}
+
+#endif
+
+#ifdef VERIFY_ALIGNMENT
+void
+valign4(const struct buffer *buf, const char *file, const int line)
+{
+    if (buf && buf->len)
+    {
+        int msglevel = D_ALIGN_DEBUG;
+        const unsigned int u = (unsigned int) BPTR(buf);
+
+        if (u & (PAYLOAD_ALIGN-1))
+        {
+            msglevel = D_ALIGN_ERRORS;
+        }
+
+        msg(msglevel, "%sAlignment at %s/%d ptr=" ptr_format " OLC=%d/%d/%d I=%s/%d",
+            (msglevel == D_ALIGN_ERRORS) ? "ERROR: " : "",
+            file,
+            line,
+            (ptr_type)buf->data,
+            buf->offset,
+            buf->len,
+            buf->capacity,
+            buf_debug_file(buf),
+            buf_debug_line(buf));
+    }
+}
+#endif /* ifdef VERIFY_ALIGNMENT */
+
+/*
+ * struct buffer_list
+ */
+struct buffer_list *
+buffer_list_new(const int max_size)
+{
+    struct buffer_list *ret;
+    ALLOC_OBJ_CLEAR(ret, struct buffer_list);
+    ret->max_size = max_size;
+    ret->size = 0;
+    return ret;
+}
+
+void
+buffer_list_free(struct buffer_list *ol)
+{
+    if (ol)
+    {
+        buffer_list_reset(ol);
+        free(ol);
+    }
+}
+
+bool
+buffer_list_defined(const struct buffer_list *ol)
+{
+    return ol && ol->head != NULL;
+}
+
+void
+buffer_list_reset(struct buffer_list *ol)
+{
+    struct buffer_entry *e = ol->head;
+    while (e)
+    {
+        struct buffer_entry *next = e->next;
+        free_buf(&e->buf);
+        free(e);
+        e = next;
+    }
+    ol->head = ol->tail = NULL;
+    ol->size = 0;
+}
+
+void
+buffer_list_push(struct buffer_list *ol, const char *str)
+{
+    if (str)
+    {
+        const size_t len = strlen((const char *)str);
+        struct buffer_entry *e = buffer_list_push_data(ol, str, len+1);
+        if (e)
+        {
+            e->buf.len = len; /* Don't count trailing '\0' as part of length */
+        }
+    }
+}
+
+struct buffer_entry *
+buffer_list_push_data(struct buffer_list *ol, const void *data, size_t size)
+{
+    struct buffer_entry *e = NULL;
+    if (data && (!ol->max_size || ol->size < ol->max_size))
+    {
+        ALLOC_OBJ_CLEAR(e, struct buffer_entry);
+
+        ++ol->size;
+        if (ol->tail)
+        {
+            ASSERT(ol->head);
+            ol->tail->next = e;
+        }
+        else
+        {
+            ASSERT(!ol->head);
+            ol->head = e;
+        }
+        e->buf = alloc_buf(size);
+        memcpy(e->buf.data, data, size);
+        e->buf.len = (int)size;
+        ol->tail = e;
+    }
+    return e;
+}
+
+struct buffer *
+buffer_list_peek(struct buffer_list *ol)
+{
+    if (ol && ol->head)
+    {
+        return &ol->head->buf;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+void
+buffer_list_aggregate_separator(struct buffer_list *bl, const size_t max_len,
+                                const char *sep)
+{
+    const int sep_len = strlen(sep);
+    struct buffer_entry *more = bl->head;
+    size_t size = 0;
+    int count = 0;
+    for (count = 0; more; ++count)
+    {
+        size_t extra_len = BLEN(&more->buf) + sep_len;
+        if (size + extra_len > max_len)
+        {
+            break;
+        }
+
+        size += extra_len;
+        more = more->next;
+    }
+
+    if (count >= 2)
+    {
+        struct buffer_entry *f;
+        ALLOC_OBJ_CLEAR(f, struct buffer_entry);
+        f->buf = alloc_buf(size + 1); /* prevent 0-byte malloc */
+
+        struct buffer_entry *e = bl->head;
+        for (size_t i = 0; e && i < count; ++i)
+        {
+            struct buffer_entry *next = e->next;
+            buf_copy(&f->buf, &e->buf);
+            buf_write(&f->buf, sep, sep_len);
+            free_buf(&e->buf);
+            free(e);
+            e = next;
+        }
+        bl->head = f;
+        bl->size -= count - 1;
+        f->next = more;
+        if (!more)
+        {
+            bl->tail = f;
+        }
+    }
+}
+
+void
+buffer_list_aggregate(struct buffer_list *bl, const size_t max)
+{
+    buffer_list_aggregate_separator(bl, max, "");
+}
+
+void
+buffer_list_pop(struct buffer_list *ol)
+{
+    if (ol && ol->head)
+    {
+        struct buffer_entry *e = ol->head->next;
+        free_buf(&ol->head->buf);
+        free(ol->head);
+        ol->head = e;
+        --ol->size;
+        if (!e)
+        {
+            ol->tail = NULL;
+        }
+    }
+}
+
+void
+buffer_list_advance(struct buffer_list *ol, int n)
+{
+    if (ol->head)
+    {
+        struct buffer *buf = &ol->head->buf;
+        ASSERT(buf_advance(buf, n));
+        if (!BLEN(buf))
+        {
+            buffer_list_pop(ol);
+        }
+    }
+}
+
+struct buffer_list *
+buffer_list_file(const char *fn, int max_line_len)
+{
+    FILE *fp = platform_fopen(fn, "r");
+    struct buffer_list *bl = NULL;
+
+    if (fp)
+    {
+        char *line = (char *) malloc(max_line_len);
+        if (line)
+        {
+            bl = buffer_list_new(0);
+            while (fgets(line, max_line_len, fp) != NULL)
+            {
+                buffer_list_push(bl, line);
+            }
+            free(line);
+        }
+        fclose(fp);
+    }
+    return bl;
+}
diff --git a/src/openvpn/buffer.h b/src/openvpn/buffer.h
new file mode 100644
index 0000000..c510c00
--- /dev/null
+++ b/src/openvpn/buffer.h
@@ -0,0 +1,1177 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef BUFFER_H
+#define BUFFER_H
+
+#include "basic.h"
+#include "error.h"
+
+#define BUF_SIZE_MAX 1000000
+
+/*
+ * Define verify_align function, otherwise
+ * it will be a noop.
+ */
+/* #define VERIFY_ALIGNMENT */
+
+/*
+ * Keep track of source file/line of buf_init calls
+ */
+#ifdef VERIFY_ALIGNMENT
+#define BUF_INIT_TRACKING
+#endif
+
+/**************************************************************************/
+/**
+ * Wrapper structure for dynamically allocated memory.
+ *
+ * The actual content stored in a \c buffer structure starts at the memory
+ * location \c buffer.data \c + \c buffer.offset, and has a length of \c
+ * buffer.len bytes.  This, together with the space available before and
+ * after the content, is represented in the pseudocode below:
+ * @code
+ * uint8_t *content_start    = buffer.data + buffer.offset;
+ * uint8_t *content_end      = buffer.data + buffer.offset + buffer.len;
+ * int      prepend_capacity = buffer.offset;
+ * int      append_capacity  = buffer.capacity - (buffer.offset + buffer.len);
+ * @endcode
+ */
+struct buffer
+{
+    int capacity;               /**< Size in bytes of memory allocated by
+                                 *   \c malloc(). */
+    int offset;                 /**< Offset in bytes of the actual content
+                                 *   within the allocated memory. */
+    int len;                    /**< Length in bytes of the actual content
+                                 *   within the allocated memory. */
+    uint8_t *data;              /**< Pointer to the allocated memory. */
+
+#ifdef BUF_INIT_TRACKING
+    const char *debug_file;
+    int debug_line;
+#endif
+};
+
+
+/**************************************************************************/
+/**
+ * Garbage collection entry for one dynamically allocated block of memory.
+ *
+ * This structure represents one link in the linked list contained in a \c
+ * gc_arena structure.  Each time the \c gc_malloc() function is called,
+ * it allocates \c sizeof(gc_entry) + the requested number of bytes.  The
+ * \c gc_entry is then stored as a header in front of the memory address
+ * returned to the caller.
+ */
+struct gc_entry
+{
+    struct gc_entry *next;      /**< Pointer to the next item in the
+                                 *   linked list. */
+};
+
+/**
+ * Garbage collection entry for a specially allocated structure that needs
+ * a custom free function to be freed like struct addrinfo
+ *
+ */
+struct gc_entry_special
+{
+    struct gc_entry_special *next;
+    void (*free_fnc)(void *);
+    void *addr;
+};
+
+
+/**
+ * Garbage collection arena used to keep track of dynamically allocated
+ * memory.
+ *
+ * This structure contains a linked list of \c gc_entry structures.  When
+ * a block of memory is allocated using the \c gc_malloc() function, the
+ * allocation is registered in the function's \c gc_arena argument.  All
+ * the dynamically allocated memory registered in a \c gc_arena can be
+ * freed using the \c gc_free() function.
+ */
+struct gc_arena
+{
+    struct gc_entry *list;      /**< First element of the linked list of
+                                 *   \c gc_entry structures. */
+    struct gc_entry_special *list_special;
+};
+
+
+#define BPTR(buf)  (buf_bptr(buf))
+#define BEND(buf)  (buf_bend(buf))
+#define BLAST(buf) (buf_blast(buf))
+#define BLEN(buf)  (buf_len(buf))
+#define BDEF(buf)  (buf_defined(buf))
+#define BSTR(buf)  (buf_str(buf))
+#define BCAP(buf)  (buf_forward_capacity(buf))
+
+void buf_clear(struct buffer *buf);
+
+struct buffer clear_buf(void);
+
+void free_buf(struct buffer *buf);
+
+bool buf_assign(struct buffer *dest, const struct buffer *src);
+
+void string_clear(char *str);
+
+int string_array_len(const char **array);
+
+size_t array_mult_safe(const size_t m1, const size_t m2, const size_t extra);
+
+#define PA_BRACKET (1<<0)
+char *print_argv(const char **p, struct gc_arena *gc, const unsigned int flags);
+
+void buf_size_error(const size_t size);
+
+/* for dmalloc debugging */
+
+#ifdef DMALLOC
+
+#define alloc_buf(size)               alloc_buf_debug(size, __FILE__, __LINE__)
+#define alloc_buf_gc(size, gc)        alloc_buf_gc_debug(size, gc, __FILE__, __LINE__);
+#define clone_buf(buf)                clone_buf_debug(buf, __FILE__, __LINE__);
+#define gc_malloc(size, clear, arena) gc_malloc_debug(size, clear, arena, __FILE__, __LINE__)
+#define string_alloc(str, gc)         string_alloc_debug(str, gc, __FILE__, __LINE__)
+#define string_alloc_buf(str, gc)     string_alloc_buf_debug(str, gc, __FILE__, __LINE__)
+
+struct buffer alloc_buf_debug(size_t size, const char *file, int line);
+
+struct buffer alloc_buf_gc_debug(size_t size, struct gc_arena *gc, const char *file, int line);
+
+struct buffer clone_buf_debug(const struct buffer *buf, const char *file, int line);
+
+void *gc_malloc_debug(size_t size, bool clear, struct gc_arena *a, const char *file, int line);
+
+char *string_alloc_debug(const char *str, struct gc_arena *gc, const char *file, int line);
+
+struct buffer string_alloc_buf_debug(const char *str, struct gc_arena *gc, const char *file, int line);
+
+#else  /* ifdef DMALLOC */
+
+struct buffer alloc_buf(size_t size);
+
+struct buffer alloc_buf_gc(size_t size, struct gc_arena *gc);  /* allocate buffer with garbage collection */
+
+struct buffer clone_buf(const struct buffer *buf);
+
+void *gc_malloc(size_t size, bool clear, struct gc_arena *a);
+
+char *string_alloc(const char *str, struct gc_arena *gc);
+
+struct buffer string_alloc_buf(const char *str, struct gc_arena *gc);
+
+#endif /* ifdef DMALLOC */
+
+void gc_addspecial(void *addr, void (*free_function)(void *), struct gc_arena *a);
+
+
+#ifdef BUF_INIT_TRACKING
+#define buf_init(buf, offset) buf_init_debug(buf, offset, __FILE__, __LINE__)
+bool buf_init_debug(struct buffer *buf, int offset, const char *file, int line);
+
+#else
+#define buf_init(buf, offset) buf_init_dowork(buf, offset)
+#endif
+
+
+/* inline functions */
+inline static void
+gc_freeaddrinfo_callback(void *addr)
+{
+    freeaddrinfo((struct addrinfo *) addr);
+}
+
+static inline bool
+buf_defined(const struct buffer *buf)
+{
+    return buf->data != NULL;
+}
+
+static inline bool
+buf_valid(const struct buffer *buf)
+{
+    return likely(buf->data != NULL) && likely(buf->len >= 0);
+}
+
+static inline uint8_t *
+buf_bptr(const struct buffer *buf)
+{
+    if (buf_valid(buf))
+    {
+        return buf->data + buf->offset;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+static int
+buf_len(const struct buffer *buf)
+{
+    if (buf_valid(buf))
+    {
+        return buf->len;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline uint8_t *
+buf_bend(const struct buffer *buf)
+{
+    return buf_bptr(buf) + buf_len(buf);
+}
+
+static inline uint8_t *
+buf_blast(const struct buffer *buf)
+{
+    if (buf_len(buf) > 0)
+    {
+        return buf_bptr(buf) + buf_len(buf) - 1;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+static inline bool
+buf_size_valid(const size_t size)
+{
+    return likely(size < BUF_SIZE_MAX);
+}
+
+static inline bool
+buf_size_valid_signed(const int size)
+{
+    return likely(size >= -BUF_SIZE_MAX) && likely(size < BUF_SIZE_MAX);
+}
+
+static inline char *
+buf_str(const struct buffer *buf)
+{
+    return (char *)buf_bptr(buf);
+}
+
+static inline void
+buf_reset(struct buffer *buf)
+{
+    buf->capacity = 0;
+    buf->offset = 0;
+    buf->len = 0;
+    buf->data = NULL;
+}
+
+static inline void
+buf_reset_len(struct buffer *buf)
+{
+    buf->len = 0;
+    buf->offset = 0;
+}
+
+static inline bool
+buf_init_dowork(struct buffer *buf, int offset)
+{
+    if (offset < 0 || offset > buf->capacity || buf->data == NULL)
+    {
+        return false;
+    }
+    buf->len = 0;
+    buf->offset = offset;
+    return true;
+}
+
+static inline void
+buf_set_write(struct buffer *buf, uint8_t *data, int size)
+{
+    if (!buf_size_valid(size))
+    {
+        buf_size_error(size);
+    }
+    buf->len = 0;
+    buf->offset = 0;
+    buf->capacity = size;
+    buf->data = data;
+    if (size > 0 && data)
+    {
+        *data = 0;
+    }
+}
+
+static inline void
+buf_set_read(struct buffer *buf, const uint8_t *data, int size)
+{
+    if (!buf_size_valid(size))
+    {
+        buf_size_error(size);
+    }
+    buf->len = buf->capacity = size;
+    buf->offset = 0;
+    buf->data = (uint8_t *)data;
+}
+
+/* Like strncpy but makes sure dest is always null terminated */
+static inline void
+strncpynt(char *dest, const char *src, size_t maxlen)
+{
+    strncpy(dest, src, maxlen);
+    if (maxlen > 0)
+    {
+        dest[maxlen - 1] = 0;
+    }
+}
+
+/* return true if string contains at least one numerical digit */
+static inline bool
+has_digit(const unsigned char *src)
+{
+    unsigned char c;
+    while ((c = *src++))
+    {
+        if (isdigit(c))
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+/**
+ * Securely zeroise memory.
+ *
+ * This code and description are based on code supplied by Zhaomo Yang, of the
+ * University of California, San Diego (which was released into the public
+ * domain).
+ *
+ * The secure_memzero function attempts to ensure that an optimizing compiler
+ * does not remove the intended operation if cleared memory is not accessed
+ * again by the program. This code has been tested under Clang 3.9.0 and GCC
+ * 6.2 with optimization flags -O, -Os, -O0, -O1, -O2, and -O3 on
+ * Ubuntu 16.04.1 LTS; under Clang 3.9.0 with optimization flags -O, -Os,
+ * -O0, -O1, -O2, and -O3 on FreeBSD 10.2-RELEASE; under Microsoft Visual Studio
+ * 2015 with optimization flags /O1, /O2 and /Ox on Windows 10.
+ *
+ * Theory of operation:
+ *
+ * 1. On Windows, use the SecureZeroMemory which ensures that data is
+ *    overwritten.
+ * 2. Under GCC or Clang, use a memory barrier, which forces the preceding
+ *    memset to be carried out. The overhead of a memory barrier is usually
+ *    negligible.
+ * 3. If none of the above are available, use the volatile pointer
+ *    technique to zero memory one byte at a time.
+ *
+ * @param data  Pointer to data to zeroise.
+ * @param len   Length of data, in bytes.
+ */
+static inline void
+secure_memzero(void *data, size_t len)
+{
+#if defined(_WIN32)
+    SecureZeroMemory(data, len);
+#elif defined(__GNUC__) || defined(__clang__)
+    memset(data, 0, len);
+    __asm__ __volatile__ ("" : : "r" (data) : "memory");
+#else
+    volatile char *p = (volatile char *) data;
+    while (len--)
+    {
+        *p++ = 0;
+    }
+#endif
+}
+
+/*
+ * printf append to a buffer with overflow check,
+ * due to usage of vsnprintf, it will leave space for
+ * a final null character and thus use only
+ * capacity - 1
+ */
+bool buf_printf(struct buffer *buf, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 2, 3)))
+#else
+__attribute__ ((format(__printf__, 2, 3)))
+#endif
+#endif
+;
+
+/*
+ * puts append to a buffer with overflow check
+ */
+bool buf_puts(struct buffer *buf, const char *str);
+
+/*
+ * Like snprintf but guarantees null termination for size > 0
+ */
+bool openvpn_snprintf(char *str, size_t size, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 3, 4)))
+#else
+__attribute__ ((format(__printf__, 3, 4)))
+#endif
+#endif
+;
+
+/*
+ * remove/add trailing characters
+ */
+
+void buf_null_terminate(struct buffer *buf);
+
+void buf_chomp(struct buffer *buf);
+
+void buf_rmtail(struct buffer *buf, uint8_t remove);
+
+/*
+ * non-buffer string functions
+ */
+void chomp(char *str);
+
+void rm_trailing_chars(char *str, const char *what_to_delete);
+
+const char *skip_leading_whitespace(const char *str);
+
+void string_null_terminate(char *str, int len, int capacity);
+
+/*
+ * Write string in buf to file descriptor fd.
+ * NOTE: requires that string be null terminated.
+ */
+void buf_write_string_file(const struct buffer *buf, const char *filename, int fd);
+
+/*
+ * write a string to the end of a buffer that was
+ * truncated by buf_printf
+ */
+void buf_catrunc(struct buffer *buf, const char *str);
+
+/*
+ * convert a multi-line output to one line
+ */
+void convert_to_one_line(struct buffer *buf);
+
+/*
+ * Parse a string based on a given delimiter char
+ */
+bool buf_parse(struct buffer *buf, const int delim, char *line, const int size);
+
+/*
+ * Hex dump -- Output a binary buffer to a hex string and return it.
+ */
+#define FHE_SPACE_BREAK_MASK 0xFF /* space_break parameter in lower 8 bits */
+#define FHE_CAPS 0x100            /* output hex in caps */
+char *
+format_hex_ex(const uint8_t *data, int size, int maxoutput,
+              unsigned int space_break_flags, const char *separator,
+              struct gc_arena *gc);
+
+static inline char *
+format_hex(const uint8_t *data, int size, int maxoutput, struct gc_arena *gc)
+{
+    return format_hex_ex(data, size, maxoutput, 4, " ", gc);
+}
+
+/*
+ * Return a buffer that is a subset of another buffer.
+ */
+struct buffer buf_sub(struct buffer *buf, int size, bool prepend);
+
+/*
+ * Check if sufficient space to append to buffer.
+ */
+
+static inline bool
+buf_safe(const struct buffer *buf, int len)
+{
+    return buf_valid(buf) && buf_size_valid(len)
+           && buf->offset + buf->len + len <= buf->capacity;
+}
+
+static inline bool
+buf_safe_bidir(const struct buffer *buf, int len)
+{
+    if (buf_valid(buf) && buf_size_valid_signed(len))
+    {
+        const int newlen = buf->len + len;
+        return newlen >= 0 && buf->offset + newlen <= buf->capacity;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static inline int
+buf_forward_capacity(const struct buffer *buf)
+{
+    if (buf_valid(buf))
+    {
+        int ret = buf->capacity - (buf->offset + buf->len);
+        if (ret < 0)
+        {
+            ret = 0;
+        }
+        return ret;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline int
+buf_forward_capacity_total(const struct buffer *buf)
+{
+    if (buf_valid(buf))
+    {
+        int ret = buf->capacity - buf->offset;
+        if (ret < 0)
+        {
+            ret = 0;
+        }
+        return ret;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline int
+buf_reverse_capacity(const struct buffer *buf)
+{
+    if (buf_valid(buf))
+    {
+        return buf->offset;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline bool
+buf_inc_len(struct buffer *buf, int inc)
+{
+    if (!buf_safe_bidir(buf, inc))
+    {
+        return false;
+    }
+    buf->len += inc;
+    return true;
+}
+
+/*
+ * Make space to prepend to a buffer.
+ * Return NULL if no space.
+ */
+
+static inline uint8_t *
+buf_prepend(struct buffer *buf, int size)
+{
+    if (!buf_valid(buf) || size < 0 || size > buf->offset)
+    {
+        return NULL;
+    }
+    buf->offset -= size;
+    buf->len += size;
+    return BPTR(buf);
+}
+
+static inline bool
+buf_advance(struct buffer *buf, int size)
+{
+    if (!buf_valid(buf) || size < 0 || buf->len < size)
+    {
+        return false;
+    }
+    buf->offset += size;
+    buf->len -= size;
+    return true;
+}
+
+/*
+ * Return a pointer to allocated space inside a buffer.
+ * Return NULL if no space.
+ */
+
+static inline uint8_t *
+buf_write_alloc(struct buffer *buf, int size)
+{
+    uint8_t *ret;
+    if (!buf_safe(buf, size))
+    {
+        return NULL;
+    }
+    ret = BPTR(buf) + buf->len;
+    buf->len += size;
+    return ret;
+}
+
+static inline uint8_t *
+buf_write_alloc_prepend(struct buffer *buf, int size, bool prepend)
+{
+    return prepend ? buf_prepend(buf, size) : buf_write_alloc(buf, size);
+}
+
+static inline uint8_t *
+buf_read_alloc(struct buffer *buf, int size)
+{
+    uint8_t *ret;
+    if (size < 0 || buf->len < size)
+    {
+        return NULL;
+    }
+    ret = BPTR(buf);
+    buf->offset += size;
+    buf->len -= size;
+    return ret;
+}
+
+static inline bool
+buf_write(struct buffer *dest, const void *src, int size)
+{
+    uint8_t *cp = buf_write_alloc(dest, size);
+    if (!cp)
+    {
+        return false;
+    }
+    memcpy(cp, src, size);
+    return true;
+}
+
+static inline bool
+buf_write_prepend(struct buffer *dest, const void *src, int size)
+{
+    uint8_t *cp = buf_prepend(dest, size);
+    if (!cp)
+    {
+        return false;
+    }
+    memcpy(cp, src, size);
+    return true;
+}
+
+static inline bool
+buf_write_u8(struct buffer *dest, int data)
+{
+    uint8_t u8 = (uint8_t) data;
+    return buf_write(dest, &u8, sizeof(uint8_t));
+}
+
+static inline bool
+buf_write_u16(struct buffer *dest, int data)
+{
+    uint16_t u16 = htons((uint16_t) data);
+    return buf_write(dest, &u16, sizeof(uint16_t));
+}
+
+static inline bool
+buf_write_u32(struct buffer *dest, int data)
+{
+    uint32_t u32 = htonl((uint32_t) data);
+    return buf_write(dest, &u32, sizeof(uint32_t));
+}
+
+static inline bool
+buf_copy(struct buffer *dest, const struct buffer *src)
+{
+    return buf_write(dest, BPTR(src), BLEN(src));
+}
+
+static inline bool
+buf_copy_n(struct buffer *dest, struct buffer *src, int n)
+{
+    uint8_t *cp = buf_read_alloc(src, n);
+    if (!cp)
+    {
+        return false;
+    }
+    return buf_write(dest, cp, n);
+}
+
+static inline bool
+buf_copy_range(struct buffer *dest,
+               int dest_index,
+               const struct buffer *src,
+               int src_index,
+               int src_len)
+{
+    if (src_index < 0
+        || src_len < 0
+        || src_index + src_len > src->len
+        || dest_index < 0
+        || dest->offset + dest_index + src_len > dest->capacity)
+    {
+        return false;
+    }
+    memcpy(dest->data + dest->offset + dest_index, src->data + src->offset + src_index, src_len);
+    if (dest_index + src_len > dest->len)
+    {
+        dest->len = dest_index + src_len;
+    }
+    return true;
+}
+
+/* truncate src to len, copy excess data beyond len to dest */
+static inline bool
+buf_copy_excess(struct buffer *dest,
+                struct buffer *src,
+                int len)
+{
+    if (len < 0)
+    {
+        return false;
+    }
+    if (src->len > len)
+    {
+        struct buffer b = *src;
+        src->len = len;
+        if (!buf_advance(&b, len))
+        {
+            return false;
+        }
+        return buf_copy(dest, &b);
+    }
+    else
+    {
+        return true;
+    }
+}
+
+static inline bool
+buf_read(struct buffer *src, void *dest, int size)
+{
+    uint8_t *cp = buf_read_alloc(src, size);
+    if (!cp)
+    {
+        return false;
+    }
+    memcpy(dest, cp, size);
+    return true;
+}
+
+static inline int
+buf_read_u8(struct buffer *buf)
+{
+    int ret;
+    if (BLEN(buf) < 1)
+    {
+        return -1;
+    }
+    ret = *BPTR(buf);
+    buf_advance(buf, 1);
+    return ret;
+}
+
+static inline int
+buf_read_u16(struct buffer *buf)
+{
+    uint16_t ret;
+    if (!buf_read(buf, &ret, sizeof(uint16_t)))
+    {
+        return -1;
+    }
+    return ntohs(ret);
+}
+
+static inline uint32_t
+buf_read_u32(struct buffer *buf, bool *good)
+{
+    uint32_t ret;
+    if (!buf_read(buf, &ret, sizeof(uint32_t)))
+    {
+        if (good)
+        {
+            *good = false;
+        }
+        return 0;
+    }
+    else
+    {
+        if (good)
+        {
+            *good = true;
+        }
+        return ntohl(ret);
+    }
+}
+
+/**
+ * Compare src buffer contents with match.
+ * *NOT* constant time. Do not use when comparing HMACs.
+ */
+static inline bool
+buf_string_match(const struct buffer *src, const void *match, int size)
+{
+    if (size != src->len)
+    {
+        return false;
+    }
+    return memcmp(BPTR(src), match, size) == 0;
+}
+
+/**
+ * Compare first size bytes of src buffer contents with match.
+ * *NOT* constant time. Do not use when comparing HMACs.
+ */
+static inline bool
+buf_string_match_head(const struct buffer *src, const void *match, int size)
+{
+    if (size < 0 || size > src->len)
+    {
+        return false;
+    }
+    return memcmp(BPTR(src), match, size) == 0;
+}
+
+bool buf_string_match_head_str(const struct buffer *src, const char *match);
+
+bool buf_string_compare_advance(struct buffer *src, const char *match);
+
+int buf_substring_len(const struct buffer *buf, int delim);
+
+/*
+ * Print a string which might be NULL
+ */
+const char *np(const char *str);
+
+/*#define CHARACTER_CLASS_DEBUG*/
+
+/* character classes */
+
+#define CC_ANY                (1<<0)
+#define CC_NULL               (1<<1)
+
+#define CC_ALNUM              (1<<2)
+#define CC_ALPHA              (1<<3)
+#define CC_ASCII              (1<<4)
+#define CC_CNTRL              (1<<5)
+#define CC_DIGIT              (1<<6)
+#define CC_PRINT              (1<<7)
+#define CC_PUNCT              (1<<8)
+#define CC_SPACE              (1<<9)
+#define CC_XDIGIT             (1<<10)
+
+#define CC_BLANK              (1<<11)
+#define CC_NEWLINE            (1<<12)
+#define CC_CR                 (1<<13)
+
+#define CC_BACKSLASH          (1<<14)
+#define CC_UNDERBAR           (1<<15)
+#define CC_DASH               (1<<16)
+#define CC_DOT                (1<<17)
+#define CC_COMMA              (1<<18)
+#define CC_COLON              (1<<19)
+#define CC_SLASH              (1<<20)
+#define CC_SINGLE_QUOTE       (1<<21)
+#define CC_DOUBLE_QUOTE       (1<<22)
+#define CC_REVERSE_QUOTE      (1<<23)
+#define CC_AT                 (1<<24)
+#define CC_EQUAL              (1<<25)
+#define CC_LESS_THAN          (1<<26)
+#define CC_GREATER_THAN       (1<<27)
+#define CC_PIPE               (1<<28)
+#define CC_QUESTION_MARK      (1<<29)
+#define CC_ASTERISK           (1<<30)
+
+/* macro classes */
+#define CC_NAME               (CC_ALNUM|CC_UNDERBAR)
+#define CC_CRLF               (CC_CR|CC_NEWLINE)
+
+bool char_class(const unsigned char c, const unsigned int flags);
+
+bool string_class(const char *str, const unsigned int inclusive, const unsigned int exclusive);
+
+bool string_mod(char *str, const unsigned int inclusive, const unsigned int exclusive, const char replace);
+
+const char *string_mod_const(const char *str,
+                             const unsigned int inclusive,
+                             const unsigned int exclusive,
+                             const char replace,
+                             struct gc_arena *gc);
+
+void string_replace_leading(char *str, const char match, const char replace);
+
+/** Return true iff str starts with prefix */
+static inline bool
+strprefix(const char *str, const char *prefix)
+{
+    return 0 == strncmp(str, prefix, strlen(prefix));
+}
+
+
+#ifdef CHARACTER_CLASS_DEBUG
+void character_class_debug(void);
+
+#endif
+
+/*
+ * Verify that a pointer is correctly aligned
+ */
+#ifdef VERIFY_ALIGNMENT
+void valign4(const struct buffer *buf, const char *file, const int line);
+
+#define verify_align_4(ptr) valign4(buf, __FILE__, __LINE__)
+#else
+#define verify_align_4(ptr)
+#endif
+
+/*
+ * Very basic garbage collection, mostly for routines that return
+ * char ptrs to malloced strings.
+ */
+
+void gc_transfer(struct gc_arena *dest, struct gc_arena *src);
+
+void x_gc_free(struct gc_arena *a);
+
+void x_gc_freespecial(struct gc_arena *a);
+
+static inline bool
+gc_defined(struct gc_arena *a)
+{
+    return a->list != NULL;
+}
+
+static inline void
+gc_init(struct gc_arena *a)
+{
+    a->list = NULL;
+    a->list_special = NULL;
+}
+
+static inline void
+gc_detach(struct gc_arena *a)
+{
+    gc_init(a);
+}
+
+static inline struct gc_arena
+gc_new(void)
+{
+    struct gc_arena ret;
+    gc_init(&ret);
+    return ret;
+}
+
+static inline void
+gc_free(struct gc_arena *a)
+{
+    if (a->list)
+    {
+        x_gc_free(a);
+    }
+    if (a->list_special)
+    {
+        x_gc_freespecial(a);
+    }
+}
+
+static inline void
+gc_reset(struct gc_arena *a)
+{
+    gc_free(a);
+}
+
+/*
+ * Allocate memory to hold a structure
+ */
+
+#define ALLOC_OBJ(dptr, type) \
+    { \
+        check_malloc_return((dptr) = (type *) malloc(sizeof(type))); \
+    }
+
+#define ALLOC_OBJ_CLEAR(dptr, type) \
+    { \
+        ALLOC_OBJ(dptr, type); \
+        memset((dptr), 0, sizeof(type)); \
+    }
+
+#define ALLOC_ARRAY(dptr, type, n) \
+    { \
+        check_malloc_return((dptr) = (type *) malloc(array_mult_safe(sizeof(type), (n), 0))); \
+    }
+
+#define ALLOC_ARRAY_GC(dptr, type, n, gc) \
+    { \
+        (dptr) = (type *) gc_malloc(array_mult_safe(sizeof(type), (n), 0), false, (gc)); \
+    }
+
+#define ALLOC_ARRAY_CLEAR(dptr, type, n) \
+    { \
+        ALLOC_ARRAY(dptr, type, n); \
+        memset((dptr), 0, (array_mult_safe(sizeof(type), (n), 0))); \
+    }
+
+#define ALLOC_ARRAY_CLEAR_GC(dptr, type, n, gc) \
+    { \
+        (dptr) = (type *) gc_malloc(array_mult_safe(sizeof(type), (n), 0), true, (gc)); \
+    }
+
+#define ALLOC_VAR_ARRAY_CLEAR_GC(dptr, type, atype, n, gc)      \
+    { \
+        (dptr) = (type *) gc_malloc(array_mult_safe(sizeof(atype), (n), sizeof(type)), true, (gc)); \
+    }
+
+#define ALLOC_OBJ_GC(dptr, type, gc) \
+    { \
+        (dptr) = (type *) gc_malloc(sizeof(type), false, (gc)); \
+    }
+
+#define ALLOC_OBJ_CLEAR_GC(dptr, type, gc) \
+    { \
+        (dptr) = (type *) gc_malloc(sizeof(type), true, (gc)); \
+    }
+
+static inline void
+check_malloc_return(const void *p)
+{
+    if (!p)
+    {
+        out_of_memory();
+    }
+}
+
+/*
+ * Manage lists of buffers
+ */
+struct buffer_entry
+{
+    struct buffer buf;
+    struct buffer_entry *next;
+};
+
+struct buffer_list
+{
+    struct buffer_entry *head; /* next item to pop/peek */
+    struct buffer_entry *tail; /* last item pushed */
+    int size;                /* current number of entries */
+    int max_size;            /* maximum size list should grow to */
+};
+
+/**
+ * Allocate an empty buffer list of capacity \c max_size.
+ *
+ * @param max_size  the capacity of the list to allocate
+ *
+ * @return the new list
+ */
+struct buffer_list *buffer_list_new(const int max_size);
+
+/**
+ * Frees a buffer list and all the buffers in it.
+ *
+ * @param ol    the list to free
+ */
+void buffer_list_free(struct buffer_list *ol);
+
+/**
+ * Checks if the list is valid and non-empty
+ *
+ * @param ol    the list to check
+ *
+ * @return true iff \c ol is not NULL and contains at least one buffer
+ */
+bool buffer_list_defined(const struct buffer_list *ol);
+
+/**
+ * Empty the list \c ol and frees all the contained buffers
+ *
+ * @param ol    the list to reset
+ */
+void buffer_list_reset(struct buffer_list *ol);
+
+/**
+ * Allocates and appends a new buffer containing \c str as data to \c ol
+ *
+ * @param ol    the list to append the new buffer to
+ * @param str   the string to copy into the new buffer
+ */
+void buffer_list_push(struct buffer_list *ol, const char *str);
+
+/**
+ * Allocates and appends a new buffer containing \c data of length \c size.
+ *
+ * @param ol    the list to append the new buffer to
+ * @param data  the data to copy into the new buffer
+ * @param size  the length of \c data to copy into the buffer
+ *
+ * @return the new buffer
+ */
+struct buffer_entry *buffer_list_push_data(struct buffer_list *ol, const void *data, size_t size);
+
+/**
+ * Retrieve the head buffer
+ *
+ * @param ol    the list to retrieve the buffer from
+ *
+ * @return a pointer to the head buffer or NULL if the list is empty
+ */
+struct buffer *buffer_list_peek(struct buffer_list *ol);
+
+void buffer_list_advance(struct buffer_list *ol, int n);
+
+void buffer_list_pop(struct buffer_list *ol);
+
+/**
+ * Aggregates as many buffers as possible from \c bl in a new buffer of maximum
+ * length \c max_len .
+ * All the aggregated buffers are removed from the list and replaced by the new
+ * one, followed by any additional (non-aggregated) data.
+ *
+ * @param bl    the list of buffer to aggregate
+ * @param max   the maximum length of the aggregated buffer
+ */
+void buffer_list_aggregate(struct buffer_list *bl, const size_t max);
+
+/**
+ * Aggregates as many buffers as possible from \c bl in a new buffer
+ * of maximum length \c max_len . \c sep is written after
+ * each copied buffer (also after the last one). All the aggregated buffers are
+ * removed from the list and replaced by the new one, followed by any additional
+ * (non-aggregated) data.
+ * Nothing happens if \c max_len is not enough to aggregate at least 2 buffers.
+ *
+ * @param bl        the list of buffer to aggregate
+ * @param max_len   the maximum length of the aggregated buffer
+ * @param sep       the separator to put between buffers during aggregation
+ */
+void buffer_list_aggregate_separator(struct buffer_list *bl,
+                                     const size_t max_len, const char *sep);
+
+struct buffer_list *buffer_list_file(const char *fn, int max_line_len);
+
+#endif /* BUFFER_H */
diff --git a/src/openvpn/circ_list.h b/src/openvpn/circ_list.h
new file mode 100644
index 0000000..23b42d2
--- /dev/null
+++ b/src/openvpn/circ_list.h
@@ -0,0 +1,77 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef CIRC_LIST_H
+#define CIRC_LIST_H
+
+#include "basic.h"
+#include "integer.h"
+#include "error.h"
+
+#define CIRC_LIST(name, type) \
+    struct name { \
+        int x_head; \
+        int x_size; \
+        int x_cap; \
+        int x_sizeof; \
+        type x_list[EMPTY_ARRAY_SIZE]; \
+    }
+
+#define CIRC_LIST_PUSH(obj, item) \
+    { \
+        (obj)->x_head = modulo_add((obj)->x_head, -1, (obj)->x_cap); \
+        (obj)->x_list[(obj)->x_head] = (item); \
+        (obj)->x_size = min_int((obj)->x_size + 1, (obj)->x_cap); \
+    }
+
+#define CIRC_LIST_SIZE(obj) \
+    ((obj)->x_size)
+
+#define CIRC_LIST_INDEX(obj, index) \
+    modulo_add((obj)->x_head, \
+               index_verify((index), (obj)->x_size, __FILE__, __LINE__), \
+               (obj)->x_cap)
+
+#define CIRC_LIST_ITEM(obj, index) \
+    ((obj)->x_list[CIRC_LIST_INDEX((obj), (index))])
+
+#define CIRC_LIST_RESET(obj) \
+    { \
+        (obj)->x_head = 0; \
+        (obj)->x_size = 0; \
+    }
+
+#define CIRC_LIST_ALLOC(dest, list_type, size) \
+    { \
+        const int so = sizeof(list_type) + sizeof((dest)->x_list[0]) * (size); \
+        (dest) = (list_type *) malloc(so); \
+        check_malloc_return(dest); \
+        memset((dest), 0, so); \
+        (dest)->x_cap = size; \
+        (dest)->x_sizeof = so; \
+    }
+
+#define CIRC_LIST_FREE(dest) \
+    free(dest)
+
+#endif /* ifndef CIRC_LIST_H */
diff --git a/src/openvpn/clinat.c b/src/openvpn/clinat.c
new file mode 100644
index 0000000..b08fd54
--- /dev/null
+++ b/src/openvpn/clinat.c
@@ -0,0 +1,278 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "clinat.h"
+#include "proto.h"
+#include "socket.h"
+#include "memdbg.h"
+
+static bool
+add_entry(struct client_nat_option_list *dest,
+          const struct client_nat_entry *e)
+{
+    if (dest->n >= MAX_CLIENT_NAT)
+    {
+        msg(M_WARN, "WARNING: client-nat table overflow (max %d entries)", MAX_CLIENT_NAT);
+        return false;
+    }
+    else
+    {
+        dest->entries[dest->n++] = *e;
+        return true;
+    }
+}
+
+void
+print_client_nat_list(const struct client_nat_option_list *list, int msglevel)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+
+    msg(msglevel, "*** CNAT list");
+    if (list)
+    {
+        for (i = 0; i < list->n; ++i)
+        {
+            const struct client_nat_entry *e = &list->entries[i];
+            msg(msglevel, "  CNAT[%d] t=%d %s/%s/%s",
+                i,
+                e->type,
+                print_in_addr_t(e->network, IA_NET_ORDER, &gc),
+                print_in_addr_t(e->netmask, IA_NET_ORDER, &gc),
+                print_in_addr_t(e->foreign_network, IA_NET_ORDER, &gc));
+        }
+    }
+    gc_free(&gc);
+}
+
+struct client_nat_option_list *
+new_client_nat_list(struct gc_arena *gc)
+{
+    struct client_nat_option_list *ret;
+    ALLOC_OBJ_CLEAR_GC(ret, struct client_nat_option_list, gc);
+    return ret;
+}
+
+struct client_nat_option_list *
+clone_client_nat_option_list(const struct client_nat_option_list *src, struct gc_arena *gc)
+{
+    struct client_nat_option_list *ret;
+    ALLOC_OBJ_GC(ret, struct client_nat_option_list, gc);
+    *ret = *src;
+    return ret;
+}
+
+void
+copy_client_nat_option_list(struct client_nat_option_list *dest,
+                            const struct client_nat_option_list *src)
+{
+    int i;
+    for (i = 0; i < src->n; ++i)
+    {
+        if (!add_entry(dest, &src->entries[i]))
+        {
+            break;
+        }
+    }
+}
+
+void
+add_client_nat_to_option_list(struct client_nat_option_list *dest,
+                              const char *type,
+                              const char *network,
+                              const char *netmask,
+                              const char *foreign_network,
+                              int msglevel)
+{
+    struct client_nat_entry e;
+    bool ok;
+
+    if (!strcmp(type, "snat"))
+    {
+        e.type = CN_SNAT;
+    }
+    else if (!strcmp(type, "dnat"))
+    {
+        e.type = CN_DNAT;
+    }
+    else
+    {
+        msg(msglevel, "client-nat: type must be 'snat' or 'dnat'");
+        return;
+    }
+
+    e.network = getaddr(0, network, 0, &ok, NULL);
+    if (!ok)
+    {
+        msg(msglevel, "client-nat: bad network: %s", network);
+        return;
+    }
+    e.netmask = getaddr(0, netmask, 0, &ok, NULL);
+    if (!ok)
+    {
+        msg(msglevel, "client-nat: bad netmask: %s", netmask);
+        return;
+    }
+    e.foreign_network = getaddr(0, foreign_network, 0, &ok, NULL);
+    if (!ok)
+    {
+        msg(msglevel, "client-nat: bad foreign network: %s", foreign_network);
+        return;
+    }
+
+    add_entry(dest, &e);
+}
+
+#if 0
+static void
+print_checksum(struct openvpn_iphdr *iph, const char *prefix)
+{
+    uint16_t *sptr;
+    unsigned int sum = 0;
+    int i = 0;
+    for (sptr = (uint16_t *)iph; (uint8_t *)sptr < (uint8_t *)iph + sizeof(struct openvpn_iphdr); sptr++)
+    {
+        i += 1;
+        sum += *sptr;
+    }
+    msg(M_INFO, "** CKSUM[%d] %s %08x", i, prefix, sum);
+}
+#endif
+
+static void
+print_pkt(struct openvpn_iphdr *iph, const char *prefix, const int direction, const int msglevel)
+{
+    struct gc_arena gc = gc_new();
+
+    char *dirstr = "???";
+    if (direction == CN_OUTGOING)
+    {
+        dirstr = "OUT";
+    }
+    else if (direction == CN_INCOMING)
+    {
+        dirstr = "IN";
+    }
+
+    msg(msglevel, "** CNAT %s %s %s -> %s",
+        dirstr,
+        prefix,
+        print_in_addr_t(iph->saddr, IA_NET_ORDER, &gc),
+        print_in_addr_t(iph->daddr, IA_NET_ORDER, &gc));
+
+    gc_free(&gc);
+}
+
+void
+client_nat_transform(const struct client_nat_option_list *list,
+                     struct buffer *ipbuf,
+                     const int direction)
+{
+    struct ip_tcp_udp_hdr *h = (struct ip_tcp_udp_hdr *) BPTR(ipbuf);
+    int i;
+    uint32_t addr, *addr_ptr;
+    const uint32_t *from, *to;
+    int accumulate = 0;
+    unsigned int amask;
+    unsigned int alog = 0;
+
+    if (check_debug_level(D_CLIENT_NAT))
+    {
+        print_pkt(&h->ip, "BEFORE", direction, D_CLIENT_NAT);
+    }
+
+    for (i = 0; i < list->n; ++i)
+    {
+        const struct client_nat_entry *e = &list->entries[i]; /* current NAT rule */
+        if (e->type ^ direction)
+        {
+            addr = *(addr_ptr = &h->ip.daddr);
+            amask = 2;
+        }
+        else
+        {
+            addr = *(addr_ptr = &h->ip.saddr);
+            amask = 1;
+        }
+        if (direction)
+        {
+            from = &e->foreign_network;
+            to = &e->network;
+        }
+        else
+        {
+            from = &e->network;
+            to = &e->foreign_network;
+        }
+
+        if (((addr & e->netmask) == *from) && !(amask & alog))
+        {
+            /* pre-adjust IP checksum */
+            ADD_CHECKSUM_32(accumulate, addr);
+
+            /* do NAT transform */
+            addr = (addr & ~e->netmask) | *to;
+
+            /* post-adjust IP checksum */
+            SUB_CHECKSUM_32(accumulate, addr);
+
+            /* write the modified address to packet */
+            *addr_ptr = addr;
+
+            /* mark as modified */
+            alog |= amask;
+        }
+    }
+    if (alog)
+    {
+        if (check_debug_level(D_CLIENT_NAT))
+        {
+            print_pkt(&h->ip, "AFTER", direction, D_CLIENT_NAT);
+        }
+
+        ADJUST_CHECKSUM(accumulate, h->ip.check);
+
+        if (h->ip.protocol == OPENVPN_IPPROTO_TCP)
+        {
+            if (BLEN(ipbuf) >= sizeof(struct openvpn_iphdr) + sizeof(struct openvpn_tcphdr))
+            {
+                ADJUST_CHECKSUM(accumulate, h->u.tcp.check);
+            }
+        }
+        else if (h->ip.protocol == OPENVPN_IPPROTO_UDP)
+        {
+            if (BLEN(ipbuf) >= sizeof(struct openvpn_iphdr) + sizeof(struct openvpn_udphdr))
+            {
+                ADJUST_CHECKSUM(accumulate, h->u.udp.check);
+            }
+        }
+    }
+}
diff --git a/src/openvpn/clinat.h b/src/openvpn/clinat.h
new file mode 100644
index 0000000..eec7a03
--- /dev/null
+++ b/src/openvpn/clinat.h
@@ -0,0 +1,67 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#if !defined(CLINAT_H)
+#define CLINAT_H
+
+#include "buffer.h"
+
+#define MAX_CLIENT_NAT 64
+
+#define CN_OUTGOING 0
+#define CN_INCOMING 1
+
+struct client_nat_entry {
+#define CN_SNAT 0
+#define CN_DNAT 1
+    int type;
+    in_addr_t network;
+    in_addr_t netmask;
+    in_addr_t foreign_network;
+};
+
+struct client_nat_option_list {
+    int n;
+    struct client_nat_entry entries[MAX_CLIENT_NAT];
+};
+
+struct client_nat_option_list *new_client_nat_list(struct gc_arena *gc);
+
+struct client_nat_option_list *clone_client_nat_option_list(const struct client_nat_option_list *src, struct gc_arena *gc);
+
+void copy_client_nat_option_list(struct client_nat_option_list *dest, const struct client_nat_option_list *src);
+
+void print_client_nat_list(const struct client_nat_option_list *list, int msglevel);
+
+void add_client_nat_to_option_list(struct client_nat_option_list *dest,
+                                   const char *type,
+                                   const char *network,
+                                   const char *netmask,
+                                   const char *foreign_network,
+                                   int msglevel);
+
+void client_nat_transform(const struct client_nat_option_list *list,
+                          struct buffer *ipbuf,
+                          const int direction);
+
+#endif /* if !defined(CLINAT_H) */
diff --git a/src/openvpn/common.h b/src/openvpn/common.h
new file mode 100644
index 0000000..0f73200
--- /dev/null
+++ b/src/openvpn/common.h
@@ -0,0 +1,104 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef COMMON_H
+#define COMMON_H
+
+/*
+ * Statistics counters and associated printf formats.
+ */
+#ifdef USE_64_BIT_COUNTERS
+typedef unsigned long long int counter_type;
+#ifdef _WIN32
+#define counter_format  "%I64u"
+#else
+#define counter_format  "%llu"
+#endif
+#else  /* ifdef USE_64_BIT_COUNTERS */
+typedef unsigned int counter_type;
+#define counter_format   "%u"
+#endif
+
+/*
+ * Time intervals
+ */
+typedef int interval_t;
+
+/*
+ * Used as an upper bound for timeouts.
+ */
+#define BIG_TIMEOUT  (60*60*24*7)  /* one week (in seconds) */
+
+/*
+ * Printf formats for special types
+ */
+#ifdef _WIN64
+#define ptr_format              "0x%I64x"
+#else
+#define ptr_format              "0x%08lx"
+#endif
+#define time_format             "%lu"
+#define fragment_header_format  "0x%08x"
+
+/* these are used to cast the arguments
+ * and MUST match the formats above */
+typedef unsigned long time_type;
+#ifdef _WIN64
+typedef unsigned long long ptr_type;
+#else
+typedef unsigned long ptr_type;
+#endif
+
+/* the --client-config-dir default file */
+#define CCD_DEFAULT "DEFAULT"
+
+/*
+ * This parameter controls the TLS channel buffer size and the
+ * maximum size of a single TLS message (cleartext).
+ * This parameter must be >= PUSH_BUNDLE_SIZE
+ */
+#define TLS_CHANNEL_BUF_SIZE 2048
+
+/*
+ * This parameter controls the maximum size of a bundle
+ * of pushed options.
+ */
+#define PUSH_BUNDLE_SIZE 1024
+
+/*
+ * In how many seconds does client re-send PUSH_REQUEST if we haven't yet received a reply
+ */
+#define PUSH_REQUEST_INTERVAL 5
+
+/*
+ * A sort of pseudo-filename for data provided inline within
+ * the configuration file.
+ */
+#define INLINE_FILE_TAG "[[INLINE]]"
+
+/*
+ * Script security warning
+ */
+#define SCRIPT_SECURITY_WARNING "WARNING: External program may not be called unless '--script-security 2' or higher is enabled. See --help text or man page for detailed info."
+
+#endif /* ifndef COMMON_H */
diff --git a/src/openvpn/comp-lz4.c b/src/openvpn/comp-lz4.c
new file mode 100644
index 0000000..f2916bd
--- /dev/null
+++ b/src/openvpn/comp-lz4.c
@@ -0,0 +1,322 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2013-2018 Gert Doering <gert@greenie.muc.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_LZ4)
+
+#if defined(NEED_COMPAT_LZ4)
+#include "compat-lz4.h"
+#else
+#include "lz4.h"
+#endif
+
+#include "comp.h"
+#include "error.h"
+
+#include "memdbg.h"
+
+
+static void
+lz4_compress_init(struct compress_context *compctx)
+{
+    msg(D_INIT_MEDIUM, "LZ4 compression initializing");
+    ASSERT(compctx->flags & COMP_F_SWAP);
+}
+
+static void
+lz4v2_compress_init(struct compress_context *compctx)
+{
+    msg(D_INIT_MEDIUM, "LZ4v2 compression initializing");
+}
+
+static void
+lz4_compress_uninit(struct compress_context *compctx)
+{
+}
+
+static bool
+do_lz4_compress(struct buffer *buf,
+                struct buffer *work,
+                struct compress_context *compctx,
+                const struct frame *frame)
+{
+    /*
+     * In order to attempt compression, length must be at least COMPRESS_THRESHOLD.
+     */
+    if (buf->len >= COMPRESS_THRESHOLD)
+    {
+        const size_t ps = PAYLOAD_SIZE(frame);
+        int zlen_max = ps + COMP_EXTRA_BUFFER(ps);
+        int zlen;
+
+        ASSERT(buf_init(work, FRAME_HEADROOM(frame)));
+        ASSERT(buf_safe(work, zlen_max));
+
+        if (buf->len > ps)
+        {
+            dmsg(D_COMP_ERRORS, "LZ4 compression buffer overflow");
+            buf->len = 0;
+            return false;
+        }
+
+        zlen = LZ4_compress_default((const char *)BPTR(buf), (char *)BPTR(work), BLEN(buf), zlen_max);
+
+        if (zlen <= 0)
+        {
+            dmsg(D_COMP_ERRORS, "LZ4 compression error");
+            buf->len = 0;
+            return false;
+        }
+
+        ASSERT(buf_safe(work, zlen));
+        work->len = zlen;
+
+
+        dmsg(D_COMP, "LZ4 compress %d -> %d", buf->len, work->len);
+        compctx->pre_compress += buf->len;
+        compctx->post_compress += work->len;
+        return true;
+    }
+    return false;
+}
+
+
+static void
+lz4_compress(struct buffer *buf, struct buffer work,
+             struct compress_context *compctx,
+             const struct frame *frame)
+{
+    bool compressed;
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    compressed = do_lz4_compress(buf, &work, compctx, frame);
+
+    /* On error do_lz4_compress sets buf len to zero, just return */
+    if (buf->len == 0)
+    {
+        return;
+    }
+
+    /* did compression save us anything? */
+    {
+        uint8_t comp_head_byte = NO_COMPRESS_BYTE_SWAP;
+        if (compressed && work.len < buf->len)
+        {
+            *buf = work;
+            comp_head_byte = LZ4_COMPRESS_BYTE;
+        }
+
+        {
+            uint8_t *head = BPTR(buf);
+            uint8_t *tail  = BEND(buf);
+            ASSERT(buf_safe(buf, 1));
+            ++buf->len;
+
+            /* move head byte of payload to tail */
+            *tail = *head;
+            *head = comp_head_byte;
+        }
+    }
+}
+
+
+static void
+lz4v2_compress(struct buffer *buf, struct buffer work,
+               struct compress_context *compctx,
+               const struct frame *frame)
+{
+    bool compressed;
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    compressed = do_lz4_compress(buf, &work, compctx, frame);
+
+    /* On Error just return */
+    if (buf->len == 0)
+    {
+        return;
+    }
+
+    /* did compression save us anything?  Include 2 byte compression header
+     * in calculation */
+    if (compressed && work.len + 2 < buf->len)
+    {
+        ASSERT(buf_prepend(&work, 2));
+        uint8_t *head = BPTR(&work);
+        head[0] = COMP_ALGV2_INDICATOR_BYTE;
+        head[1] = COMP_ALGV2_LZ4_BYTE;
+        *buf = work;
+    }
+    else
+    {
+        compv2_escape_data_ifneeded(buf);
+    }
+}
+
+static void
+do_lz4_decompress(size_t zlen_max,
+                  struct buffer *work,
+                  struct buffer *buf,
+                  struct compress_context *compctx)
+{
+    int uncomp_len;
+    ASSERT(buf_safe(work, zlen_max));
+    uncomp_len = LZ4_decompress_safe((const char *)BPTR(buf), (char *)BPTR(work), (size_t)BLEN(buf), zlen_max);
+    if (uncomp_len <= 0)
+    {
+        dmsg(D_COMP_ERRORS, "LZ4 decompression error: %d", uncomp_len);
+        buf->len = 0;
+        return;
+    }
+
+    ASSERT(buf_safe(work, uncomp_len));
+    work->len = uncomp_len;
+
+    dmsg(D_COMP, "LZ4 decompress %d -> %d", buf->len, work->len);
+    compctx->pre_decompress += buf->len;
+    compctx->post_decompress += work->len;
+
+    *buf = *work;
+}
+
+static void
+lz4_decompress(struct buffer *buf, struct buffer work,
+               struct compress_context *compctx,
+               const struct frame *frame)
+{
+    size_t zlen_max = EXPANDED_SIZE(frame);
+    uint8_t c;          /* flag indicating whether or not our peer compressed */
+
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
+
+    /* do unframing/swap (assumes buf->len > 0) */
+    {
+        uint8_t *head = BPTR(buf);
+        c = *head;
+        --buf->len;
+        *head = *BEND(buf);
+    }
+
+    if (c == LZ4_COMPRESS_BYTE) /* packet was compressed */
+    {
+        do_lz4_decompress(zlen_max, &work, buf, compctx);
+    }
+    else if (c == NO_COMPRESS_BYTE_SWAP) /* packet was not compressed */
+    {
+    }
+    else
+    {
+        dmsg(D_COMP_ERRORS, "Bad LZ4 decompression header byte: %d", c);
+        buf->len = 0;
+    }
+}
+
+static void
+lz4v2_decompress(struct buffer *buf, struct buffer work,
+                 struct compress_context *compctx,
+                 const struct frame *frame)
+{
+    size_t zlen_max = EXPANDED_SIZE(frame);
+    uint8_t c;          /* flag indicating whether or not our peer compressed */
+
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
+
+    /* do unframing/swap (assumes buf->len > 0) */
+    uint8_t *head = BPTR(buf);
+    c = *head;
+
+    /* Not compressed */
+    if (c != COMP_ALGV2_INDICATOR_BYTE)
+    {
+        return;
+    }
+
+    /* Packet to short to make sense */
+    if (buf->len <= 1)
+    {
+        buf->len = 0;
+        return;
+    }
+
+    c = head[1];
+    if (c == COMP_ALGV2_LZ4_BYTE) /* packet was compressed */
+    {
+        buf_advance(buf,2);
+        do_lz4_decompress(zlen_max, &work, buf, compctx);
+    }
+    else if (c == COMP_ALGV2_UNCOMPRESSED_BYTE)
+    {
+        buf_advance(buf,2);
+    }
+    else
+    {
+        dmsg(D_COMP_ERRORS, "Bad LZ4v2 decompression header byte: %d", c);
+        buf->len = 0;
+    }
+}
+
+const struct compress_alg lz4_alg = {
+    "lz4",
+    lz4_compress_init,
+    lz4_compress_uninit,
+    lz4_compress,
+    lz4_decompress
+};
+
+const struct compress_alg lz4v2_alg = {
+    "lz4v2",
+    lz4v2_compress_init,
+    lz4_compress_uninit,
+    lz4v2_compress,
+    lz4v2_decompress
+};
+
+#else  /* if defined(ENABLE_LZ4) */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_LZ4 */
diff --git a/src/openvpn/comp-lz4.h b/src/openvpn/comp-lz4.h
new file mode 100644
index 0000000..8c1ca3a
--- /dev/null
+++ b/src/openvpn/comp-lz4.h
@@ -0,0 +1,41 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2013-2018 Gert Doering <gert@greenie.muc.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_COMP_LZ4_H
+#define OPENVPN_COMP_LZ4_H
+
+#if defined(ENABLE_LZ4)
+
+#include "buffer.h"
+
+extern const struct compress_alg lz4_alg;
+extern const struct compress_alg lz4v2_alg;
+
+struct lz4_workspace
+{
+    int dummy;
+};
+
+#endif /* ENABLE_LZ4 */
+#endif
diff --git a/src/openvpn/comp.c b/src/openvpn/comp.c
new file mode 100644
index 0000000..a945913
--- /dev/null
+++ b/src/openvpn/comp.c
@@ -0,0 +1,176 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef USE_COMP
+
+#include "comp.h"
+#include "error.h"
+#include "otime.h"
+
+#include "memdbg.h"
+
+struct compress_context *
+comp_init(const struct compress_options *opt)
+{
+    struct compress_context *compctx = NULL;
+    switch (opt->alg)
+    {
+        case COMP_ALG_STUB:
+            ALLOC_OBJ_CLEAR(compctx, struct compress_context);
+            compctx->flags = opt->flags;
+            compctx->alg = comp_stub_alg;
+            break;
+
+        case COMP_ALGV2_UNCOMPRESSED:
+            ALLOC_OBJ_CLEAR(compctx, struct compress_context);
+            compctx->flags = opt->flags;
+            compctx->alg = compv2_stub_alg;
+            break;
+
+#ifdef ENABLE_LZO
+        case COMP_ALG_LZO:
+            ALLOC_OBJ_CLEAR(compctx, struct compress_context);
+            compctx->flags = opt->flags;
+            compctx->alg = lzo_alg;
+            break;
+
+#endif
+#ifdef ENABLE_LZ4
+        case COMP_ALG_LZ4:
+            ALLOC_OBJ_CLEAR(compctx, struct compress_context);
+            compctx->flags = opt->flags;
+            compctx->alg = lz4_alg;
+            break;
+
+        case COMP_ALGV2_LZ4:
+            ALLOC_OBJ_CLEAR(compctx, struct compress_context);
+            compctx->flags = opt->flags;
+            compctx->alg = lz4v2_alg;
+            break;
+#endif
+    }
+    if (compctx)
+    {
+        (*compctx->alg.compress_init)(compctx);
+    }
+
+    return compctx;
+}
+
+/* In the v2 compression schemes, an uncompressed packet has
+ * has no opcode in front, unless the first byte is 0x50. In this
+ * case the packet needs to be escaped */
+void
+compv2_escape_data_ifneeded(struct buffer *buf)
+{
+    uint8_t *head = BPTR(buf);
+    if (head[0] != COMP_ALGV2_INDICATOR_BYTE)
+    {
+        return;
+    }
+
+    /* Header is 0x50 */
+    ASSERT(buf_prepend(buf, 2));
+
+    head = BPTR(buf);
+    head[0] = COMP_ALGV2_INDICATOR_BYTE;
+    head[1] = COMP_ALGV2_UNCOMPRESSED;
+}
+
+
+void
+comp_uninit(struct compress_context *compctx)
+{
+    if (compctx)
+    {
+        (*compctx->alg.compress_uninit)(compctx);
+        free(compctx);
+    }
+}
+
+void
+comp_add_to_extra_frame(struct frame *frame)
+{
+    /* Leave room for our one-byte compressed/didn't-compress prefix byte. */
+    frame_add_to_extra_frame(frame, COMP_PREFIX_LEN);
+}
+
+void
+comp_add_to_extra_buffer(struct frame *frame)
+{
+    /* Leave room for compression buffer to expand in worst case scenario
+     * where data is totally uncompressible */
+    frame_add_to_extra_buffer(frame, COMP_EXTRA_BUFFER(EXPANDED_SIZE(frame)));
+}
+
+void
+comp_print_stats(const struct compress_context *compctx, struct status_output *so)
+{
+    if (compctx)
+    {
+        status_printf(so, "pre-compress bytes," counter_format, compctx->pre_compress);
+        status_printf(so, "post-compress bytes," counter_format, compctx->post_compress);
+        status_printf(so, "pre-decompress bytes," counter_format, compctx->pre_decompress);
+        status_printf(so, "post-decompress bytes," counter_format, compctx->post_decompress);
+    }
+}
+
+/*
+ * Tell our peer which compression algorithms we support.
+ */
+void
+comp_generate_peer_info_string(const struct compress_options *opt, struct buffer *out)
+{
+    if (opt)
+    {
+        bool lzo_avail = false;
+        if (!(opt->flags & COMP_F_ADVERTISE_STUBS_ONLY))
+        {
+#if defined(ENABLE_LZ4)
+            buf_printf(out, "IV_LZ4=1\n");
+            buf_printf(out, "IV_LZ4v2=1\n");
+#endif
+#if defined(ENABLE_LZO)
+            buf_printf(out, "IV_LZO=1\n");
+            lzo_avail = true;
+#endif
+        }
+        if (!lzo_avail)
+        {
+            buf_printf(out, "IV_LZO_STUB=1\n");
+        }
+        buf_printf(out, "IV_COMP_STUB=1\n");
+        buf_printf(out, "IV_COMP_STUBv2=1\n");
+        buf_printf(out, "IV_TCPNL=1\n");
+    }
+}
+
+#endif /* USE_COMP */
diff --git a/src/openvpn/comp.h b/src/openvpn/comp.h
new file mode 100644
index 0000000..0dadd1e
--- /dev/null
+++ b/src/openvpn/comp.h
@@ -0,0 +1,198 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Generic compression support.  Currently we support
+ * LZO 2 and LZ4.
+ */
+#ifndef OPENVPN_COMP_H
+#define OPENVPN_COMP_H
+
+#ifdef USE_COMP
+
+#include "buffer.h"
+#include "mtu.h"
+#include "common.h"
+#include "status.h"
+
+/* algorithms */
+#define COMP_ALG_UNDEF  0
+#define COMP_ALG_STUB   1 /* support compression command byte and framing without actual compression */
+#define COMP_ALG_LZO    2 /* LZO algorithm */
+#define COMP_ALG_SNAPPY 3 /* Snappy algorithm (no longer supported) */
+#define COMP_ALG_LZ4    4 /* LZ4 algorithm */
+
+
+/* algorithm v2 */
+#define COMP_ALGV2_UNCOMPRESSED 10
+#define COMP_ALGV2_LZ4      11
+/*
+ #define COMP_ALGV2_LZO     12
+ #define COMP_ALGV2_SNAPPY   13
+ */
+
+/* Compression flags */
+#define COMP_F_ADAPTIVE   (1<<0) /* COMP_ALG_LZO only */
+#define COMP_F_ASYM       (1<<1) /* only downlink is compressed, not uplink */
+#define COMP_F_SWAP       (1<<2) /* initial command byte is swapped with last byte in buffer to preserve payload alignment */
+#define COMP_F_ADVERTISE_STUBS_ONLY (1<<3) /* tell server that we only support compression stubs */
+
+
+/*
+ * Length of prepended prefix on compressed packets
+ */
+#define COMP_PREFIX_LEN 1
+
+/*
+ * Prefix bytes
+ */
+
+/* V1 on wire codes */
+/* Initial command byte to tell our peer if we compressed */
+#define LZO_COMPRESS_BYTE 0x66
+#define LZ4_COMPRESS_BYTE 0x69
+#define NO_COMPRESS_BYTE      0xFA
+#define NO_COMPRESS_BYTE_SWAP 0xFB /* to maintain payload alignment, replace this byte with last byte of packet */
+
+/* V2 on wire code */
+#define COMP_ALGV2_INDICATOR_BYTE       0x50
+#define COMP_ALGV2_UNCOMPRESSED_BYTE    0
+#define COMP_ALGV2_LZ4_BYTE             1
+#define COMP_ALGV2_LZO_BYTE             2
+#define COMP_ALGV2_SNAPPY_BYTE          3
+
+/*
+ * Compress worst case size expansion (for any algorithm)
+ *
+ * LZO:    len + len/8 + 128 + 3
+ * Snappy: len + len/6 + 32
+ * LZ4:    len + len/255 + 16  (LZ4_COMPRESSBOUND(len))
+ */
+#define COMP_EXTRA_BUFFER(len) ((len)/6 + 128 + 3 + COMP_PREFIX_LEN)
+
+/*
+ * Don't try to compress any packet smaller than this.
+ */
+#define COMPRESS_THRESHOLD 100
+
+/* Forward declaration of compression context */
+struct compress_context;
+
+/*
+ * Virtual methods and other static info for each compression algorithm
+ */
+struct compress_alg
+{
+    const char *name;
+    void (*compress_init)(struct compress_context *compctx);
+    void (*compress_uninit)(struct compress_context *compctx);
+    void (*compress)(struct buffer *buf, struct buffer work,
+                     struct compress_context *compctx,
+                     const struct frame *frame);
+
+    void (*decompress)(struct buffer *buf, struct buffer work,
+                       struct compress_context *compctx,
+                       const struct frame *frame);
+};
+
+/*
+ * Headers for each compression implementation
+ */
+#ifdef ENABLE_LZO
+#include "lzo.h"
+#endif
+
+#ifdef ENABLE_LZ4
+#include "comp-lz4.h"
+#endif
+
+/*
+ * Information that basically identifies a compression
+ * algorithm and related flags.
+ */
+struct compress_options
+{
+    int alg;
+    unsigned int flags;
+};
+
+/*
+ * Workspace union of all supported compression algorithms
+ */
+union compress_workspace_union
+{
+#ifdef ENABLE_LZO
+    struct lzo_compress_workspace lzo;
+#endif
+#ifdef ENABLE_LZ4
+    struct lz4_workspace lz4;
+#endif
+};
+
+/*
+ * Context for active compression session
+ */
+struct compress_context
+{
+    unsigned int flags;
+    struct compress_alg alg;
+    union compress_workspace_union wu;
+
+    /* statistics */
+    counter_type pre_decompress;
+    counter_type post_decompress;
+    counter_type pre_compress;
+    counter_type post_compress;
+};
+
+extern const struct compress_alg comp_stub_alg;
+extern const struct compress_alg compv2_stub_alg;
+
+struct compress_context *comp_init(const struct compress_options *opt);
+
+void comp_uninit(struct compress_context *compctx);
+
+void comp_add_to_extra_frame(struct frame *frame);
+
+void comp_add_to_extra_buffer(struct frame *frame);
+
+void comp_print_stats(const struct compress_context *compctx, struct status_output *so);
+
+void comp_generate_peer_info_string(const struct compress_options *opt, struct buffer *out);
+
+void compv2_escape_data_ifneeded(struct buffer *buf);
+
+static inline bool
+comp_enabled(const struct compress_options *info)
+{
+    return info->alg != COMP_ALG_UNDEF;
+}
+
+static inline bool
+comp_unswapped_prefix(const struct compress_options *info)
+{
+    return !(info->flags & COMP_F_SWAP);
+}
+
+#endif /* USE_COMP */
+#endif /* ifndef OPENVPN_COMP_H */
diff --git a/src/openvpn/compstub.c b/src/openvpn/compstub.c
new file mode 100644
index 0000000..9123541
--- /dev/null
+++ b/src/openvpn/compstub.c
@@ -0,0 +1,184 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(USE_COMP)
+
+#include "comp.h"
+#include "error.h"
+#include "otime.h"
+
+#include "memdbg.h"
+
+static void
+stub_compress_init(struct compress_context *compctx)
+{
+}
+
+static void
+stub_compress_uninit(struct compress_context *compctx)
+{
+}
+
+static void
+stub_compress(struct buffer *buf, struct buffer work,
+              struct compress_context *compctx,
+              const struct frame *frame)
+{
+    if (buf->len <= 0)
+    {
+        return;
+    }
+    if (compctx->flags & COMP_F_SWAP)
+    {
+        uint8_t *head = BPTR(buf);
+        uint8_t *tail  = BEND(buf);
+        ASSERT(buf_safe(buf, 1));
+        ++buf->len;
+
+        /* move head byte of payload to tail */
+        *tail = *head;
+        *head = NO_COMPRESS_BYTE_SWAP;
+    }
+    else
+    {
+        uint8_t *header = buf_prepend(buf, 1);
+        *header = NO_COMPRESS_BYTE;
+    }
+}
+
+static void
+stub_decompress(struct buffer *buf, struct buffer work,
+                struct compress_context *compctx,
+                const struct frame *frame)
+{
+    uint8_t c;
+    if (buf->len <= 0)
+    {
+        return;
+    }
+    if (compctx->flags & COMP_F_SWAP)
+    {
+        uint8_t *head = BPTR(buf);
+        c = *head;
+        --buf->len;
+        *head = *BEND(buf);
+        if (c != NO_COMPRESS_BYTE_SWAP)
+        {
+            dmsg(D_COMP_ERRORS, "Bad compression stub (swap) decompression header byte: %d", c);
+            buf->len = 0;
+        }
+    }
+    else
+    {
+        c = *BPTR(buf);
+        ASSERT(buf_advance(buf, 1));
+        if (c != NO_COMPRESS_BYTE)
+        {
+            dmsg(D_COMP_ERRORS, "Bad compression stub decompression header byte: %d", c);
+            buf->len = 0;
+        }
+    }
+}
+
+
+static void
+stubv2_compress(struct buffer *buf, struct buffer work,
+                struct compress_context *compctx,
+                const struct frame *frame)
+{
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    compv2_escape_data_ifneeded(buf);
+}
+
+static void
+stubv2_decompress(struct buffer *buf, struct buffer work,
+                  struct compress_context *compctx,
+                  const struct frame *frame)
+{
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    uint8_t *head = BPTR(buf);
+
+    /* no compression or packet to short*/
+    if (head[0] != COMP_ALGV2_INDICATOR_BYTE)
+    {
+        return;
+    }
+
+    /* compression header (0x50) is present */
+    buf_advance(buf, 1);
+
+    /* Packet buffer too short (only 1 byte) */
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    head = BPTR(buf);
+    buf_advance(buf, 1);
+
+    if (head[0] != COMP_ALGV2_UNCOMPRESSED_BYTE)
+    {
+        dmsg(D_COMP_ERRORS, "Bad compression stubv2 decompression header byte: %d", *head);
+        buf->len = 0;
+        return;
+    }
+}
+
+const struct compress_alg compv2_stub_alg = {
+    "stubv2",
+    stub_compress_init,
+    stub_compress_uninit,
+    stubv2_compress,
+    stubv2_decompress
+};
+
+const struct compress_alg comp_stub_alg = {
+    "stub",
+    stub_compress_init,
+    stub_compress_uninit,
+    stub_compress,
+    stub_decompress
+};
+
+#else  /* if defined(USE_COMP) */
+static void
+dummy(void)
+{
+}
+#endif /* USE_STUB */
diff --git a/src/openvpn/console.c b/src/openvpn/console.c
new file mode 100644
index 0000000..4d49722
--- /dev/null
+++ b/src/openvpn/console.c
@@ -0,0 +1,86 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2014-2015 David Sommerseth <davids@redhat.com>
+ *  Copyright (C) 2016-2018 David Sommerseth <davids@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "console.h"
+#include "error.h"
+#include "buffer.h"
+#include "misc.h"
+
+#ifdef ENABLE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
+
+struct _query_user query_user[QUERY_USER_NUMSLOTS];  /* GLOBAL */
+
+
+void
+query_user_clear(void)
+{
+    int i;
+
+    for (i = 0; i < QUERY_USER_NUMSLOTS; i++)
+    {
+        CLEAR(query_user[i]);
+    }
+}
+
+
+void
+query_user_add(char *prompt, size_t prompt_len,
+               char *resp, size_t resp_len,
+               bool echo)
+{
+    int i;
+
+    /* Ensure input is sane.  All these must be present otherwise it is
+     * a programming error.
+     */
+    ASSERT( prompt_len > 0 && prompt != NULL && resp_len > 0 && resp != NULL );
+
+    /* Seek to the last unused slot */
+    for (i = 0; i < QUERY_USER_NUMSLOTS; i++)
+    {
+        if (query_user[i].prompt == NULL)
+        {
+            break;
+        }
+    }
+    ASSERT( i < QUERY_USER_NUMSLOTS );  /* Unlikely, but we want to panic if it happens */
+
+    /* Save the information needed for the user interaction */
+    query_user[i].prompt = prompt;
+    query_user[i].prompt_len = prompt_len;
+    query_user[i].response = resp;
+    query_user[i].response_len = resp_len;
+    query_user[i].echo = echo;
+}
diff --git a/src/openvpn/console.h b/src/openvpn/console.h
new file mode 100644
index 0000000..5a70e5f
--- /dev/null
+++ b/src/openvpn/console.h
@@ -0,0 +1,119 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2014-2015 David Sommerseth <davids@redhat.com>
+ *  Copyright (C) 2016-2018 David Sommerseth <davids@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#ifndef CONSOLE_H
+#define CONSOLE_H
+
+#include "basic.h"
+
+/**
+ *  Configuration setup for declaring what kind of information to ask a user for
+ */
+struct _query_user {
+    char *prompt;             /**< Prompt to present to the user */
+    size_t prompt_len;        /**< Lenght of the prompt string */
+    char *response;           /**< The user's response */
+    size_t response_len;      /**< Lenght the of the user reposone */
+    bool echo;                /**< True: The user should see what is being typed, otherwise mask it */
+};
+
+#define QUERY_USER_NUMSLOTS 10
+extern struct _query_user query_user[];  /**< Global variable, declared in console.c */
+
+/**
+ * Wipes all data put into all of the query_user structs
+ *
+ */
+void query_user_clear(void);
+
+
+/**
+ * Adds an item to ask the user for
+ *
+ * @param prompt     Prompt to display to the user
+ * @param prompt_len Length of the prompt string
+ * @param resp       String containing the user response
+ * @param resp_len   Lenght of the response string
+ * @param echo       Should the user input be echoed to the user?  If False, input will be masked
+ *
+ */
+void query_user_add(char *prompt, size_t prompt_len,
+                    char *resp, size_t resp_len,
+                    bool echo);
+
+
+/**
+ * Executes a configured setup, using the built-in method for querying the user.
+ * This method uses the console/TTY directly.
+ *
+ * @param setup    Pointer to the setup defining what to ask the user
+ *
+ * @return True if executing all the defined steps completed successfully
+ */
+bool query_user_exec_builtin(void);
+
+
+#if defined(ENABLE_SYSTEMD)
+/**
+ * Executes a configured setup, using the compiled method for querying the user
+ *
+ * @param setup    Pointer to the setup defining what to ask the user
+ *
+ * @return True if executing all the defined steps completed successfully
+ */
+bool query_user_exec(void);
+
+#else  /* ENABLE_SYSTEMD not defined*/
+/**
+ * Wrapper function enabling query_user_exec() if no alternative methods have
+ * been enabled
+ *
+ */
+static bool
+query_user_exec(void)
+{
+    return query_user_exec_builtin();
+}
+#endif  /* defined(ENABLE_SYSTEMD) */
+
+
+/**
+ * A plain "make Gert happy" wrapper.  Same arguments as @query_user_add
+ *
+ * FIXME/TODO: Remove this when refactoring the complete user query process
+ *             to be called at start-up initialization of OpenVPN.
+ *
+ */
+static inline bool
+query_user_SINGLE(char *prompt, size_t prompt_len,
+                  char *resp, size_t resp_len,
+                  bool echo)
+{
+    query_user_clear();
+    query_user_add(prompt, prompt_len, resp, resp_len, echo);
+    return query_user_exec();
+}
+
+#endif /* ifndef CONSOLE_H */
diff --git a/src/openvpn/console_builtin.c b/src/openvpn/console_builtin.c
new file mode 100644
index 0000000..445928b
--- /dev/null
+++ b/src/openvpn/console_builtin.c
@@ -0,0 +1,287 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2014-2015  David Sommerseth <davids@redhat.com>
+ *  Copyright (C) 2016-2018 David Sommerseth <davids@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ *  These functions covers handing user input/output using the default consoles
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "console.h"
+#include "error.h"
+#include "buffer.h"
+#include "misc.h"
+
+#ifdef _WIN32
+
+#include "win32.h"
+
+/**
+ * Get input from a Windows console.
+ *
+ * @param prompt    Prompt to display to the user
+ * @param echo      Should the user input be displayed in the console
+ * @param input     Pointer to the buffer the user input will be saved
+ * @param capacity  Size of the buffer for the user input
+ *
+ * @return Return false on input error, or if service
+ *         exit event is signaled.
+ */
+static bool
+get_console_input_win32(const char *prompt, const bool echo, char *input, const int capacity)
+{
+    HANDLE in = INVALID_HANDLE_VALUE;
+    HANDLE err = INVALID_HANDLE_VALUE;
+    DWORD len = 0;
+
+    ASSERT(prompt);
+    ASSERT(input);
+    ASSERT(capacity > 0);
+
+    input[0] = '\0';
+
+    in = GetStdHandle(STD_INPUT_HANDLE);
+    err = get_orig_stderr();
+
+    if (in != INVALID_HANDLE_VALUE
+        && err != INVALID_HANDLE_VALUE
+        && !win32_service_interrupt(&win32_signal)
+        && WriteFile(err, prompt, strlen(prompt), &len, NULL))
+    {
+        bool is_console = (GetFileType(in) == FILE_TYPE_CHAR);
+        DWORD flags_save = 0;
+        int status = 0;
+        WCHAR *winput;
+
+        if (is_console)
+        {
+            if (GetConsoleMode(in, &flags_save))
+            {
+                DWORD flags = ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT;
+                if (echo)
+                {
+                    flags |= ENABLE_ECHO_INPUT;
+                }
+                SetConsoleMode(in, flags);
+            }
+            else
+            {
+                is_console = 0;
+            }
+        }
+
+        if (is_console)
+        {
+            winput = malloc(capacity * sizeof(WCHAR));
+            if (winput == NULL)
+            {
+                return false;
+            }
+
+            status = ReadConsoleW(in, winput, capacity, &len, NULL);
+            WideCharToMultiByte(CP_UTF8, 0, winput, len, input, capacity, NULL, NULL);
+            free(winput);
+        }
+        else
+        {
+            status = ReadFile(in, input, capacity, &len, NULL);
+        }
+
+        string_null_terminate(input, (int)len, capacity);
+        chomp(input);
+
+        if (!echo)
+        {
+            WriteFile(err, "\r\n", 2, &len, NULL);
+        }
+        if (is_console)
+        {
+            SetConsoleMode(in, flags_save);
+        }
+        if (status && !win32_service_interrupt(&win32_signal))
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+#endif   /* _WIN32 */
+
+
+#ifdef HAVE_GETPASS
+
+/**
+ * Open the current console TTY for read/write operations
+ *
+ * @params write   If true, the user wants to write to the console
+ *                 otherwise read from the console
+ *
+ * @returns Returns a FILE pointer to either the TTY in read or write mode
+ *          or stdin/stderr, depending on the write flag
+ *
+ */
+static FILE *
+open_tty(const bool write)
+{
+    FILE *ret;
+    ret = fopen("/dev/tty", write ? "w" : "r");
+    if (!ret)
+    {
+        ret = write ? stderr : stdin;
+    }
+    return ret;
+}
+
+/**
+ * Closes the TTY FILE pointer, but only if it is not a stdin/stderr FILE object.
+ *
+ * @params fp     FILE pointer to close
+ *
+ */
+static void
+close_tty(FILE *fp)
+{
+    if (fp != stderr && fp != stdin)
+    {
+        fclose(fp);
+    }
+}
+
+#endif   /* HAVE_GETPASS */
+
+
+/**
+ *  Core function for getting input from console
+ *
+ *  @params prompt    The prompt to present to the user
+ *  @params echo      Should the user see what is being typed
+ *  @params input     Pointer to the buffer used to save the user input
+ *  @params capacity  Size of the input buffer
+ *
+ *  @returns Returns True if user input was gathered
+ */
+static bool
+get_console_input(const char *prompt, const bool echo, char *input, const int capacity)
+{
+    bool ret = false;
+    ASSERT(prompt);
+    ASSERT(input);
+    ASSERT(capacity > 0);
+    input[0] = '\0';
+
+#if defined(_WIN32)
+    return get_console_input_win32(prompt, echo, input, capacity);
+#elif defined(HAVE_GETPASS)
+
+    /* did we --daemon'ize before asking for passwords?
+     * (in which case neither stdin or stderr are connected to a tty and
+     * /dev/tty can not be open()ed anymore)
+     */
+    if (!isatty(0) && !isatty(2) )
+    {
+        int fd = open( "/dev/tty", O_RDWR );
+        if (fd < 0)
+        {
+            msg(M_FATAL, "neither stdin nor stderr are a tty device and you have neither a "
+                "controlling tty nor systemd - can't ask for '%s'.  If you used --daemon, "
+                "you need to use --askpass to make passphrase-protected keys work, and you "
+                "can not use --auth-nocache.", prompt );
+        }
+        close(fd);
+    }
+
+    if (echo)
+    {
+        FILE *fp;
+
+        fp = open_tty(true);
+        fprintf(fp, "%s", prompt);
+        fflush(fp);
+        close_tty(fp);
+
+        fp = open_tty(false);
+        if (fgets(input, capacity, fp) != NULL)
+        {
+            chomp(input);
+            ret = true;
+        }
+        close_tty(fp);
+    }
+    else
+    {
+        char *gp = getpass(prompt);
+        if (gp)
+        {
+            strncpynt(input, gp, capacity);
+            secure_memzero(gp, strlen(gp));
+            ret = true;
+        }
+    }
+#else  /* if defined(_WIN32) */
+    msg(M_FATAL, "Sorry, but I can't get console input on this OS (%s)", prompt);
+#endif /* if defined(_WIN32) */
+    return ret;
+}
+
+
+/**
+ * @copydoc query_user_exec()
+ *
+ * Default method for querying user using default stdin/stdout on a console.
+ * This needs to be available as a backup interface for the alternative
+ * implementations in case they cannot query through their implementation
+ * specific methods.
+ *
+ * If no alternative implementation is declared, a wrapper in console.h will ensure
+ * query_user_exec() will call this function instead.
+ *
+ */
+bool
+query_user_exec_builtin(void)
+{
+    bool ret = true; /* Presume everything goes okay */
+    int i;
+
+    /* Loop through configured query_user slots */
+    for (i = 0; i < QUERY_USER_NUMSLOTS && query_user[i].response != NULL; i++)
+    {
+        if (!get_console_input(query_user[i].prompt, query_user[i].echo,
+                               query_user[i].response, query_user[i].response_len) )
+        {
+            /* Force the final result state to failed on failure */
+            ret = false;
+        }
+    }
+
+    return ret;
+}
diff --git a/src/openvpn/console_systemd.c b/src/openvpn/console_systemd.c
new file mode 100644
index 0000000..e7a72ae
--- /dev/null
+++ b/src/openvpn/console_systemd.c
@@ -0,0 +1,123 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2014-2015 David Sommerseth <davids@redhat.com>
+ *  Copyright (C) 2016      David Sommerseth <dazo@privateinternetaccess.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Alternative method to query for user input, using systemd
+ *
+ */
+
+#include "config.h"
+
+#ifdef ENABLE_SYSTEMD
+#include "syshead.h"
+#include "console.h"
+#include "misc.h"
+
+#include <systemd/sd-daemon.h>
+
+/*
+ * is systemd running
+ */
+
+static bool
+check_systemd_running(void)
+{
+    struct stat c;
+
+    /* We simply test whether the systemd cgroup hierarchy is
+     * mounted, as well as the systemd-ask-password executable
+     * being available */
+
+    return (sd_booted() > 0)
+           && (stat(SYSTEMD_ASK_PASSWORD_PATH, &c) == 0);
+
+}
+
+static bool
+get_console_input_systemd(const char *prompt, const bool echo, char *input, const int capacity)
+{
+    int std_out;
+    bool ret = false;
+    struct argv argv = argv_new();
+
+    argv_printf(&argv, SYSTEMD_ASK_PASSWORD_PATH);
+#ifdef SYSTEMD_NEWER_THAN_216
+    /* the --echo support arrived in upstream systemd 217 */
+    if (echo)
+    {
+        argv_printf_cat(&argv, "--echo");
+    }
+#endif
+    argv_printf_cat(&argv, "--icon network-vpn");
+    argv_printf_cat(&argv, "%s", prompt);
+
+    if ((std_out = openvpn_popen(&argv, NULL)) < 0)
+    {
+        return false;
+    }
+    memset(input, 0, capacity);
+    if (read(std_out, input, capacity-1) != 0)
+    {
+        chomp(input);
+        ret = true;
+    }
+    close(std_out);
+
+    argv_reset(&argv);
+
+    return ret;
+}
+
+/**
+ *  Systemd aware implementation of query_user_exec().  If systemd is not running
+ *  it will fall back to use query_user_exec_builtin() instead.
+ *
+ */
+bool
+query_user_exec(void)
+{
+    bool ret = true;  /* Presume everything goes okay */
+    int i;
+
+    /* If systemd is not available, use the default built-in mechanism */
+    if (!check_systemd_running())
+    {
+        return query_user_exec_builtin();
+    }
+
+    /* Loop through the complete query setup and when needed, collect the information */
+    for (i = 0; i < QUERY_USER_NUMSLOTS && query_user[i].response != NULL; i++)
+    {
+        if (!get_console_input_systemd(query_user[i].prompt, query_user[i].echo,
+                                       query_user[i].response, query_user[i].response_len) )
+        {
+            /* Force the final result state to failed on failure */
+            ret = false;
+        }
+    }
+
+    return ret;
+}
+
+#endif /* ENABLE_SYSTEMD */
diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
new file mode 100644
index 0000000..7e7dead
--- /dev/null
+++ b/src/openvpn/crypto.c
@@ -0,0 +1,1875 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "crypto.h"
+#include "error.h"
+#include "integer.h"
+#include "platform.h"
+
+#include "memdbg.h"
+
+/*
+ * Encryption and Compression Routines.
+ *
+ * On entry, buf contains the input data and length.
+ * On exit, it should be set to the output data and length.
+ *
+ * If buf->len is <= 0 we should return
+ * If buf->len is set to 0 on exit it tells the caller to ignore the packet.
+ *
+ * work is a workspace buffer we are given of size BUF_SIZE.
+ * work may be used to return output data, or the input buffer
+ * may be modified and returned as output.  If output data is
+ * returned in work, the data should start after FRAME_HEADROOM bytes
+ * of padding to leave room for downstream routines to prepend.
+ *
+ * Up to a total of FRAME_HEADROOM bytes may be prepended to the input buf
+ * by all routines (encryption, decryption, compression, and decompression).
+ *
+ * Note that the buf_prepend return will assert if we try to
+ * make a header bigger than FRAME_HEADROOM.  This should not
+ * happen unless the frame parameters are wrong.
+ */
+
+static void
+openvpn_encrypt_aead(struct buffer *buf, struct buffer work,
+                     struct crypto_options *opt)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    struct gc_arena gc;
+    int outlen = 0;
+    const struct key_ctx *ctx = &opt->key_ctx_bi.encrypt;
+    uint8_t *mac_out = NULL;
+    const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt(ctx->cipher);
+    const int mac_len = cipher_kt_tag_size(cipher_kt);
+
+    /* IV, packet-ID and implicit IV required for this mode. */
+    ASSERT(ctx->cipher);
+    ASSERT(cipher_kt_mode_aead(cipher_kt));
+    ASSERT(opt->flags & CO_USE_IV);
+    ASSERT(packet_id_initialized(&opt->packet_id));
+
+    gc_init(&gc);
+
+    /* Prepare IV */
+    {
+        struct buffer iv_buffer;
+        uint8_t iv[OPENVPN_MAX_IV_LENGTH] = {0};
+        const int iv_len = cipher_ctx_iv_length(ctx->cipher);
+
+        ASSERT(iv_len >= OPENVPN_AEAD_MIN_IV_LEN && iv_len <= OPENVPN_MAX_IV_LENGTH);
+
+        buf_set_write(&iv_buffer, iv, iv_len);
+
+        /* IV starts with packet id to make the IV unique for packet */
+        if (!packet_id_write(&opt->packet_id.send, &iv_buffer, false, false))
+        {
+            msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
+            goto err;
+        }
+
+        /* Remainder of IV consists of implicit part (unique per session) */
+        ASSERT(buf_write(&iv_buffer, ctx->implicit_iv, ctx->implicit_iv_len));
+        ASSERT(iv_buffer.len == iv_len);
+
+        /* Write explicit part of IV to work buffer */
+        ASSERT(buf_write(&work, iv, iv_len - ctx->implicit_iv_len));
+        dmsg(D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex(iv, iv_len, 0, &gc));
+
+        /* Init cipher_ctx with IV.  key & keylen are already initialized */
+        ASSERT(cipher_ctx_reset(ctx->cipher, iv));
+    }
+
+    /* Reserve space for authentication tag */
+    mac_out = buf_write_alloc(&work, mac_len);
+    ASSERT(mac_out);
+
+    dmsg(D_PACKET_CONTENT, "ENCRYPT FROM: %s", format_hex(BPTR(buf), BLEN(buf), 80, &gc));
+
+    /* Buffer overflow check */
+    if (!buf_safe(&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+    {
+        msg(D_CRYPT_ERRORS,
+            "ENCRYPT: buffer size error, bc=%d bo=%d bl=%d wc=%d wo=%d wl=%d",
+            buf->capacity, buf->offset, buf->len, work.capacity, work.offset,
+            work.len);
+        goto err;
+    }
+
+    /* For AEAD ciphers, authenticate Additional Data, including opcode */
+    ASSERT(cipher_ctx_update_ad(ctx->cipher, BPTR(&work), BLEN(&work) - mac_len));
+    dmsg(D_PACKET_CONTENT, "ENCRYPT AD: %s",
+         format_hex(BPTR(&work), BLEN(&work) - mac_len, 0, &gc));
+
+    /* Encrypt packet ID, payload */
+    ASSERT(cipher_ctx_update(ctx->cipher, BEND(&work), &outlen, BPTR(buf), BLEN(buf)));
+    ASSERT(buf_inc_len(&work, outlen));
+
+    /* Flush the encryption buffer */
+    ASSERT(cipher_ctx_final(ctx->cipher, BEND(&work), &outlen));
+    ASSERT(buf_inc_len(&work, outlen));
+
+    /* Write authentication tag */
+    ASSERT(cipher_ctx_get_tag(ctx->cipher, mac_out, mac_len));
+
+    *buf = work;
+
+    dmsg(D_PACKET_CONTENT, "ENCRYPT TO: %s", format_hex(BPTR(buf), BLEN(buf), 80, &gc));
+
+    gc_free(&gc);
+    return;
+
+err:
+    crypto_clear_error();
+    buf->len = 0;
+    gc_free(&gc);
+    return;
+#else /* HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif /* ifdef HAVE_AEAD_CIPHER_MODES */
+}
+
+static void
+openvpn_encrypt_v1(struct buffer *buf, struct buffer work,
+                   struct crypto_options *opt)
+{
+    struct gc_arena gc;
+    gc_init(&gc);
+
+    if (buf->len > 0 && opt)
+    {
+        const struct key_ctx *ctx = &opt->key_ctx_bi.encrypt;
+        uint8_t *mac_out = NULL;
+        const uint8_t *hmac_start = NULL;
+
+        /* Do Encrypt from buf -> work */
+        if (ctx->cipher)
+        {
+            uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH] = {0};
+            const int iv_size = cipher_ctx_iv_length(ctx->cipher);
+            const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt(ctx->cipher);
+            int outlen;
+
+            /* Reserve space for HMAC */
+            if (ctx->hmac)
+            {
+                mac_out = buf_write_alloc(&work, hmac_ctx_size(ctx->hmac));
+                ASSERT(mac_out);
+                hmac_start = BEND(&work);
+            }
+
+            if (cipher_kt_mode_cbc(cipher_kt))
+            {
+                /* generate pseudo-random IV */
+                if (opt->flags & CO_USE_IV)
+                {
+                    prng_bytes(iv_buf, iv_size);
+                }
+
+                /* Put packet ID in plaintext buffer */
+                if (packet_id_initialized(&opt->packet_id)
+                    && !packet_id_write(&opt->packet_id.send, buf,
+                                        opt->flags & CO_PACKET_ID_LONG_FORM,
+                                        true))
+                {
+                    msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
+                    goto err;
+                }
+            }
+            else if (cipher_kt_mode_ofb_cfb(cipher_kt))
+            {
+                struct buffer b;
+
+                /* IV and packet-ID required for this mode. */
+                ASSERT(opt->flags & CO_USE_IV);
+                ASSERT(packet_id_initialized(&opt->packet_id));
+
+                buf_set_write(&b, iv_buf, iv_size);
+                ASSERT(packet_id_write(&opt->packet_id.send, &b, true, false));
+            }
+            else /* We only support CBC, CFB, or OFB modes right now */
+            {
+                ASSERT(0);
+            }
+
+            /* set the IV pseudo-randomly */
+            if (opt->flags & CO_USE_IV)
+            {
+                ASSERT(buf_write(&work, iv_buf, iv_size));
+                dmsg(D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex(iv_buf, iv_size, 0, &gc));
+            }
+
+            dmsg(D_PACKET_CONTENT, "ENCRYPT FROM: %s",
+                 format_hex(BPTR(buf), BLEN(buf), 80, &gc));
+
+            /* cipher_ctx was already initialized with key & keylen */
+            ASSERT(cipher_ctx_reset(ctx->cipher, iv_buf));
+
+            /* Buffer overflow check */
+            if (!buf_safe(&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+            {
+                msg(D_CRYPT_ERRORS, "ENCRYPT: buffer size error, bc=%d bo=%d bl=%d wc=%d wo=%d wl=%d cbs=%d",
+                    buf->capacity,
+                    buf->offset,
+                    buf->len,
+                    work.capacity,
+                    work.offset,
+                    work.len,
+                    cipher_ctx_block_size(ctx->cipher));
+                goto err;
+            }
+
+            /* Encrypt packet ID, payload */
+            ASSERT(cipher_ctx_update(ctx->cipher, BEND(&work), &outlen, BPTR(buf), BLEN(buf)));
+            ASSERT(buf_inc_len(&work, outlen));
+
+            /* Flush the encryption buffer */
+            ASSERT(cipher_ctx_final(ctx->cipher, BEND(&work), &outlen));
+            ASSERT(buf_inc_len(&work, outlen));
+
+            /* For all CBC mode ciphers, check the last block is complete */
+            ASSERT(cipher_kt_mode(cipher_kt) != OPENVPN_MODE_CBC
+                   || outlen == iv_size);
+        }
+        else                            /* No Encryption */
+        {
+            if (packet_id_initialized(&opt->packet_id)
+                && !packet_id_write(&opt->packet_id.send, buf,
+                                    opt->flags & CO_PACKET_ID_LONG_FORM, true))
+            {
+                msg(D_CRYPT_ERRORS, "ENCRYPT ERROR: packet ID roll over");
+                goto err;
+            }
+            if (ctx->hmac)
+            {
+                hmac_start = BPTR(buf);
+                ASSERT(mac_out = buf_prepend(buf, hmac_ctx_size(ctx->hmac)));
+            }
+            if (BLEN(&work))
+            {
+                buf_write_prepend(buf, BPTR(&work), BLEN(&work));
+            }
+            work = *buf;
+        }
+
+        /* HMAC the ciphertext (or plaintext if !cipher) */
+        if (ctx->hmac)
+        {
+            hmac_ctx_reset(ctx->hmac);
+            hmac_ctx_update(ctx->hmac, hmac_start, BEND(&work) - hmac_start);
+            hmac_ctx_final(ctx->hmac, mac_out);
+            dmsg(D_PACKET_CONTENT, "ENCRYPT HMAC: %s",
+                 format_hex(mac_out, hmac_ctx_size(ctx->hmac), 80, &gc));
+        }
+
+        *buf = work;
+
+        dmsg(D_PACKET_CONTENT, "ENCRYPT TO: %s",
+             format_hex(BPTR(&work), BLEN(&work), 80, &gc));
+    }
+
+    gc_free(&gc);
+    return;
+
+err:
+    crypto_clear_error();
+    buf->len = 0;
+    gc_free(&gc);
+    return;
+}
+
+void
+openvpn_encrypt(struct buffer *buf, struct buffer work,
+                struct crypto_options *opt)
+{
+    if (buf->len > 0 && opt)
+    {
+        const cipher_kt_t *cipher_kt =
+            cipher_ctx_get_cipher_kt(opt->key_ctx_bi.encrypt.cipher);
+
+        if (cipher_kt_mode_aead(cipher_kt))
+        {
+            openvpn_encrypt_aead(buf, work, opt);
+        }
+        else
+        {
+            openvpn_encrypt_v1(buf, work, opt);
+        }
+    }
+}
+
+bool
+crypto_check_replay(struct crypto_options *opt,
+                    const struct packet_id_net *pin, const char *error_prefix,
+                    struct gc_arena *gc)
+{
+    bool ret = false;
+    packet_id_reap_test(&opt->packet_id.rec);
+    if (packet_id_test(&opt->packet_id.rec, pin))
+    {
+        packet_id_add(&opt->packet_id.rec, pin);
+        if (opt->pid_persist && (opt->flags & CO_PACKET_ID_LONG_FORM))
+        {
+            packet_id_persist_save_obj(opt->pid_persist, &opt->packet_id);
+        }
+        ret = true;
+    }
+    else
+    {
+        if (!(opt->flags & CO_MUTE_REPLAY_WARNINGS))
+        {
+            msg(D_REPLAY_ERRORS, "%s: bad packet ID (may be a replay): %s -- "
+                "see the man page entry for --no-replay and --replay-window for "
+                "more info or silence this warning with --mute-replay-warnings",
+                error_prefix, packet_id_net_print(pin, true, gc));
+        }
+    }
+    return ret;
+}
+
+/*
+ * If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet.
+ *
+ * Set buf->len to 0 and return false on decrypt error.
+ *
+ * On success, buf is set to point to plaintext, true
+ * is returned.
+ */
+static bool
+openvpn_decrypt_aead(struct buffer *buf, struct buffer work,
+                     struct crypto_options *opt, const struct frame *frame,
+                     const uint8_t *ad_start)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    static const char error_prefix[] = "AEAD Decrypt error";
+    struct packet_id_net pin = { 0 };
+    const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+    const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt(ctx->cipher);
+    uint8_t *tag_ptr = NULL;
+    int tag_size = 0;
+    int outlen;
+    struct gc_arena gc;
+
+    gc_init(&gc);
+
+    ASSERT(opt);
+    ASSERT(frame);
+    ASSERT(buf->len > 0);
+    ASSERT(ctx->cipher);
+    ASSERT(cipher_kt_mode_aead(cipher_kt));
+
+    dmsg(D_PACKET_CONTENT, "DECRYPT FROM: %s",
+         format_hex(BPTR(buf), BLEN(buf), 80, &gc));
+
+    ASSERT(ad_start >= buf->data && ad_start <= BPTR(buf));
+
+    ASSERT(buf_init(&work, FRAME_HEADROOM_ADJ(frame, FRAME_HEADROOM_MARKER_DECRYPT)));
+
+    /* IV and Packet ID required for this mode */
+    ASSERT(packet_id_initialized(&opt->packet_id));
+    ASSERT(opt->flags & CO_USE_IV);
+
+    /* Combine IV from explicit part from packet and implicit part from context */
+    {
+        uint8_t iv[OPENVPN_MAX_IV_LENGTH] = { 0 };
+        const int iv_len = cipher_ctx_iv_length(ctx->cipher);
+        const size_t packet_iv_len = iv_len - ctx->implicit_iv_len;
+
+        ASSERT(ctx->implicit_iv_len <= iv_len);
+        if (buf->len + ctx->implicit_iv_len < iv_len)
+        {
+            CRYPT_ERROR("missing IV info");
+        }
+
+        memcpy(iv, BPTR(buf), packet_iv_len);
+        memcpy(iv + packet_iv_len, ctx->implicit_iv, ctx->implicit_iv_len);
+
+        dmsg(D_PACKET_CONTENT, "DECRYPT IV: %s", format_hex(iv, iv_len, 0, &gc));
+
+        /* Load IV, ctx->cipher was already initialized with key & keylen */
+        if (!cipher_ctx_reset(ctx->cipher, iv))
+        {
+            CRYPT_ERROR("cipher init failed");
+        }
+    }
+
+    /* Read packet ID from packet */
+    if (!packet_id_read(&pin, buf, false))
+    {
+        CRYPT_ERROR("error reading packet-id");
+    }
+
+    /* keep the tag value to feed in later */
+    tag_size = cipher_kt_tag_size(cipher_kt);
+    if (buf->len < tag_size)
+    {
+        CRYPT_ERROR("missing tag");
+    }
+    tag_ptr = BPTR(buf);
+    ASSERT(buf_advance(buf, tag_size));
+    dmsg(D_PACKET_CONTENT, "DECRYPT MAC: %s", format_hex(tag_ptr, tag_size, 0, &gc));
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER < 0x10001040L
+    /* OpenSSL <= 1.0.1c bug requires set tag before processing ciphertext */
+    if (!EVP_CIPHER_CTX_ctrl(ctx->cipher, EVP_CTRL_GCM_SET_TAG, tag_size, tag_ptr))
+    {
+        CRYPT_ERROR("setting tag failed");
+    }
+#endif
+
+    if (buf->len < 1)
+    {
+        CRYPT_ERROR("missing payload");
+    }
+
+    dmsg(D_PACKET_CONTENT, "DECRYPT FROM: %s", format_hex(BPTR(buf), BLEN(buf), 0, &gc));
+
+    /* Buffer overflow check (should never fail) */
+    if (!buf_safe(&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+    {
+        CRYPT_ERROR("potential buffer overflow");
+    }
+
+    {
+        /* feed in tag and the authenticated data */
+        const int ad_size = BPTR(buf) - ad_start - tag_size;
+        ASSERT(cipher_ctx_update_ad(ctx->cipher, ad_start, ad_size));
+        dmsg(D_PACKET_CONTENT, "DECRYPT AD: %s",
+             format_hex(BPTR(buf) - ad_size - tag_size, ad_size, 0, &gc));
+    }
+
+    /* Decrypt and authenticate packet */
+    if (!cipher_ctx_update(ctx->cipher, BPTR(&work), &outlen, BPTR(buf),
+                           BLEN(buf)))
+    {
+        CRYPT_ERROR("cipher update failed");
+    }
+    ASSERT(buf_inc_len(&work, outlen));
+    if (!cipher_ctx_final_check_tag(ctx->cipher, BPTR(&work) + outlen,
+                                    &outlen, tag_ptr, tag_size))
+    {
+        CRYPT_ERROR("cipher final failed");
+    }
+    ASSERT(buf_inc_len(&work, outlen));
+
+    dmsg(D_PACKET_CONTENT, "DECRYPT TO: %s",
+         format_hex(BPTR(&work), BLEN(&work), 80, &gc));
+
+    if (!crypto_check_replay(opt, &pin, error_prefix, &gc))
+    {
+        goto error_exit;
+    }
+
+    *buf = work;
+
+    gc_free(&gc);
+    return true;
+
+error_exit:
+    crypto_clear_error();
+    buf->len = 0;
+    gc_free(&gc);
+    return false;
+#else /* HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+    return false;
+#endif /* ifdef HAVE_AEAD_CIPHER_MODES */
+}
+
+/*
+ * If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet.
+ *
+ * Set buf->len to 0 and return false on decrypt error.
+ *
+ * On success, buf is set to point to plaintext, true
+ * is returned.
+ */
+static bool
+openvpn_decrypt_v1(struct buffer *buf, struct buffer work,
+                   struct crypto_options *opt, const struct frame *frame)
+{
+    static const char error_prefix[] = "Authenticate/Decrypt packet error";
+    struct gc_arena gc;
+    gc_init(&gc);
+
+    if (buf->len > 0 && opt)
+    {
+        const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+        struct packet_id_net pin;
+        bool have_pin = false;
+
+        dmsg(D_PACKET_CONTENT, "DECRYPT FROM: %s",
+             format_hex(BPTR(buf), BLEN(buf), 80, &gc));
+
+        /* Verify the HMAC */
+        if (ctx->hmac)
+        {
+            int hmac_len;
+            uint8_t local_hmac[MAX_HMAC_KEY_LENGTH]; /* HMAC of ciphertext computed locally */
+
+            hmac_ctx_reset(ctx->hmac);
+
+            /* Assume the length of the input HMAC */
+            hmac_len = hmac_ctx_size(ctx->hmac);
+
+            /* Authentication fails if insufficient data in packet for HMAC */
+            if (buf->len < hmac_len)
+            {
+                CRYPT_ERROR("missing authentication info");
+            }
+
+            hmac_ctx_update(ctx->hmac, BPTR(buf) + hmac_len, BLEN(buf) - hmac_len);
+            hmac_ctx_final(ctx->hmac, local_hmac);
+
+            /* Compare locally computed HMAC with packet HMAC */
+            if (memcmp_constant_time(local_hmac, BPTR(buf), hmac_len))
+            {
+                CRYPT_ERROR("packet HMAC authentication failed");
+            }
+
+            ASSERT(buf_advance(buf, hmac_len));
+        }
+
+        /* Decrypt packet ID + payload */
+
+        if (ctx->cipher)
+        {
+            const int iv_size = cipher_ctx_iv_length(ctx->cipher);
+            const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt(ctx->cipher);
+            uint8_t iv_buf[OPENVPN_MAX_IV_LENGTH] = { 0 };
+            int outlen;
+
+            /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+            ASSERT(buf_init(&work, FRAME_HEADROOM_ADJ(frame, FRAME_HEADROOM_MARKER_DECRYPT)));
+
+            /* use IV if user requested it */
+            if (opt->flags & CO_USE_IV)
+            {
+                if (buf->len < iv_size)
+                {
+                    CRYPT_ERROR("missing IV info");
+                }
+                memcpy(iv_buf, BPTR(buf), iv_size);
+                ASSERT(buf_advance(buf, iv_size));
+            }
+
+            /* show the IV's initial state */
+            if (opt->flags & CO_USE_IV)
+            {
+                dmsg(D_PACKET_CONTENT, "DECRYPT IV: %s", format_hex(iv_buf, iv_size, 0, &gc));
+            }
+
+            if (buf->len < 1)
+            {
+                CRYPT_ERROR("missing payload");
+            }
+
+            /* ctx->cipher was already initialized with key & keylen */
+            if (!cipher_ctx_reset(ctx->cipher, iv_buf))
+            {
+                CRYPT_ERROR("cipher init failed");
+            }
+
+            /* Buffer overflow check (should never happen) */
+            if (!buf_safe(&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+            {
+                CRYPT_ERROR("potential buffer overflow");
+            }
+
+            /* Decrypt packet ID, payload */
+            if (!cipher_ctx_update(ctx->cipher, BPTR(&work), &outlen, BPTR(buf), BLEN(buf)))
+            {
+                CRYPT_ERROR("cipher update failed");
+            }
+            ASSERT(buf_inc_len(&work, outlen));
+
+            /* Flush the decryption buffer */
+            if (!cipher_ctx_final(ctx->cipher, BPTR(&work) + outlen, &outlen))
+            {
+                CRYPT_ERROR("cipher final failed");
+            }
+            ASSERT(buf_inc_len(&work, outlen));
+
+            dmsg(D_PACKET_CONTENT, "DECRYPT TO: %s",
+                 format_hex(BPTR(&work), BLEN(&work), 80, &gc));
+
+            /* Get packet ID from plaintext buffer or IV, depending on cipher mode */
+            {
+                if (cipher_kt_mode_cbc(cipher_kt))
+                {
+                    if (packet_id_initialized(&opt->packet_id))
+                    {
+                        if (!packet_id_read(&pin, &work, BOOL_CAST(opt->flags & CO_PACKET_ID_LONG_FORM)))
+                        {
+                            CRYPT_ERROR("error reading CBC packet-id");
+                        }
+                        have_pin = true;
+                    }
+                }
+                else if (cipher_kt_mode_ofb_cfb(cipher_kt))
+                {
+                    struct buffer b;
+
+                    /* IV and packet-ID required for this mode. */
+                    ASSERT(opt->flags & CO_USE_IV);
+                    ASSERT(packet_id_initialized(&opt->packet_id));
+
+                    buf_set_read(&b, iv_buf, iv_size);
+                    if (!packet_id_read(&pin, &b, true))
+                    {
+                        CRYPT_ERROR("error reading CFB/OFB packet-id");
+                    }
+                    have_pin = true;
+                }
+                else /* We only support CBC, CFB, or OFB modes right now */
+                {
+                    ASSERT(0);
+                }
+            }
+        }
+        else
+        {
+            work = *buf;
+            if (packet_id_initialized(&opt->packet_id))
+            {
+                if (!packet_id_read(&pin, &work, BOOL_CAST(opt->flags & CO_PACKET_ID_LONG_FORM)))
+                {
+                    CRYPT_ERROR("error reading packet-id");
+                }
+                have_pin = !BOOL_CAST(opt->flags & CO_IGNORE_PACKET_ID);
+            }
+        }
+
+        if (have_pin && !crypto_check_replay(opt, &pin, error_prefix, &gc))
+        {
+            goto error_exit;
+        }
+        *buf = work;
+    }
+
+    gc_free(&gc);
+    return true;
+
+error_exit:
+    crypto_clear_error();
+    buf->len = 0;
+    gc_free(&gc);
+    return false;
+}
+
+
+bool
+openvpn_decrypt(struct buffer *buf, struct buffer work,
+                struct crypto_options *opt, const struct frame *frame,
+                const uint8_t *ad_start)
+{
+    bool ret = false;
+
+    if (buf->len > 0 && opt)
+    {
+        const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+        if (cipher_kt_mode_aead(cipher_ctx_get_cipher_kt(ctx->cipher)))
+        {
+            ret = openvpn_decrypt_aead(buf, work, opt, frame, ad_start);
+        }
+        else
+        {
+            ret = openvpn_decrypt_v1(buf, work, opt, frame);
+        }
+    }
+    else
+    {
+        ret = true;
+    }
+    return ret;
+}
+
+void
+crypto_adjust_frame_parameters(struct frame *frame,
+                               const struct key_type *kt,
+                               bool use_iv,
+                               bool packet_id,
+                               bool packet_id_long_form)
+{
+    unsigned int crypto_overhead = 0;
+
+    if (packet_id)
+    {
+        crypto_overhead += packet_id_size(packet_id_long_form);
+    }
+
+    if (kt->cipher)
+    {
+        if (use_iv)
+        {
+            crypto_overhead += cipher_kt_iv_size(kt->cipher);
+        }
+
+        if (cipher_kt_mode_aead(kt->cipher))
+        {
+            crypto_overhead += cipher_kt_tag_size(kt->cipher);
+        }
+
+        /* extra block required by cipher_ctx_update() */
+        crypto_overhead += cipher_kt_block_size(kt->cipher);
+    }
+
+    crypto_overhead += kt->hmac_length;
+
+    frame_add_to_extra_frame(frame, crypto_overhead);
+
+    msg(D_MTU_DEBUG, "%s: Adjusting frame parameters for crypto by %u bytes",
+        __func__, crypto_overhead);
+}
+
+unsigned int
+crypto_max_overhead(void)
+{
+    return packet_id_size(true) + OPENVPN_MAX_IV_LENGTH
+           +OPENVPN_MAX_CIPHER_BLOCK_SIZE
+           +max_int(OPENVPN_MAX_HMAC_SIZE, OPENVPN_AEAD_TAG_LENGTH);
+}
+
+/*
+ * Build a struct key_type.
+ */
+void
+init_key_type(struct key_type *kt, const char *ciphername,
+              const char *authname, int keysize, bool tls_mode, bool warn)
+{
+    bool aead_cipher = false;
+
+    ASSERT(ciphername);
+    ASSERT(authname);
+
+    CLEAR(*kt);
+    if (strcmp(ciphername, "none") != 0)
+    {
+        kt->cipher = cipher_kt_get(translate_cipher_name_from_openvpn(ciphername));
+        if (!kt->cipher)
+        {
+            msg(M_FATAL, "Cipher %s not supported", ciphername);
+        }
+
+        kt->cipher_length = cipher_kt_key_size(kt->cipher);
+        if (keysize > 0 && keysize <= MAX_CIPHER_KEY_LENGTH)
+        {
+            kt->cipher_length = keysize;
+        }
+
+        /* check legal cipher mode */
+        aead_cipher = cipher_kt_mode_aead(kt->cipher);
+        if (!(cipher_kt_mode_cbc(kt->cipher)
+              || (tls_mode && aead_cipher)
+#ifdef ENABLE_OFB_CFB_MODE
+              || (tls_mode && cipher_kt_mode_ofb_cfb(kt->cipher))
+#endif
+              ))
+        {
+            msg(M_FATAL, "Cipher '%s' mode not supported", ciphername);
+        }
+
+        if (OPENVPN_MAX_CIPHER_BLOCK_SIZE < cipher_kt_block_size(kt->cipher))
+        {
+            msg(M_FATAL, "Cipher '%s' not allowed: block size too big.", ciphername);
+        }
+    }
+    else
+    {
+        if (warn)
+        {
+            msg(M_WARN, "******* WARNING *******: '--cipher none' was specified. "
+                "This means NO encryption will be performed and tunnelled "
+                "data WILL be transmitted in clear text over the network! "
+                "PLEASE DO RECONSIDER THIS SETTING!");
+        }
+    }
+    if (strcmp(authname, "none") != 0)
+    {
+        if (!aead_cipher) /* Ignore auth for AEAD ciphers */
+        {
+            kt->digest = md_kt_get(authname);
+            kt->hmac_length = md_kt_size(kt->digest);
+
+            if (OPENVPN_MAX_HMAC_SIZE < kt->hmac_length)
+            {
+                msg(M_FATAL, "HMAC '%s' not allowed: digest size too big.", authname);
+            }
+        }
+    }
+    else if (!aead_cipher)
+    {
+        if (warn)
+        {
+            msg(M_WARN, "******* WARNING *******: '--auth none' was specified. "
+                "This means no authentication will be performed on received "
+                "packets, meaning you CANNOT trust that the data received by "
+                "the remote side have NOT been manipulated. "
+                "PLEASE DO RECONSIDER THIS SETTING!");
+        }
+    }
+}
+
+/* given a key and key_type, build a key_ctx */
+void
+init_key_ctx(struct key_ctx *ctx, const struct key *key,
+             const struct key_type *kt, int enc,
+             const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+    CLEAR(*ctx);
+    if (kt->cipher && kt->cipher_length > 0)
+    {
+
+        ctx->cipher = cipher_ctx_new();
+        cipher_ctx_init(ctx->cipher, key->cipher, kt->cipher_length,
+                        kt->cipher, enc);
+
+        msg(D_HANDSHAKE, "%s: Cipher '%s' initialized with %d bit key",
+            prefix,
+            translate_cipher_name_to_openvpn(cipher_kt_name(kt->cipher)),
+            kt->cipher_length *8);
+
+        dmsg(D_SHOW_KEYS, "%s: CIPHER KEY: %s", prefix,
+             format_hex(key->cipher, kt->cipher_length, 0, &gc));
+        dmsg(D_CRYPTO_DEBUG, "%s: CIPHER block_size=%d iv_size=%d",
+             prefix, cipher_kt_block_size(kt->cipher),
+             cipher_kt_iv_size(kt->cipher));
+        if (cipher_kt_block_size(kt->cipher) < 128/8)
+        {
+            msg(M_WARN, "WARNING: INSECURE cipher with block size less than 128"
+                " bit (%d bit).  This allows attacks like SWEET32.  Mitigate by "
+                "using a --cipher with a larger block size (e.g. AES-256-CBC).",
+                cipher_kt_block_size(kt->cipher)*8);
+        }
+    }
+    if (kt->digest && kt->hmac_length > 0)
+    {
+        ctx->hmac = hmac_ctx_new();
+        hmac_ctx_init(ctx->hmac, key->hmac, kt->hmac_length, kt->digest);
+
+        msg(D_HANDSHAKE,
+            "%s: Using %d bit message hash '%s' for HMAC authentication",
+            prefix, md_kt_size(kt->digest) * 8, md_kt_name(kt->digest));
+
+        dmsg(D_SHOW_KEYS, "%s: HMAC KEY: %s", prefix,
+             format_hex(key->hmac, kt->hmac_length, 0, &gc));
+
+        dmsg(D_CRYPTO_DEBUG, "%s: HMAC size=%d block_size=%d",
+             prefix,
+             md_kt_size(kt->digest),
+             hmac_ctx_size(ctx->hmac));
+
+    }
+    gc_free(&gc);
+}
+
+void
+init_key_ctx_bi(struct key_ctx_bi *ctx, const struct key2 *key2,
+                int key_direction, const struct key_type *kt, const char *name)
+{
+    char log_prefix[128] = { 0 };
+    struct key_direction_state kds;
+
+    key_direction_state_init(&kds, key_direction);
+
+    openvpn_snprintf(log_prefix, sizeof(log_prefix), "Outgoing %s", name);
+    init_key_ctx(&ctx->encrypt, &key2->keys[kds.out_key], kt,
+                 OPENVPN_OP_ENCRYPT, log_prefix);
+
+    openvpn_snprintf(log_prefix, sizeof(log_prefix), "Incoming %s", name);
+    init_key_ctx(&ctx->decrypt, &key2->keys[kds.in_key], kt,
+                 OPENVPN_OP_DECRYPT, log_prefix);
+
+    ctx->initialized = true;
+}
+
+void
+free_key_ctx(struct key_ctx *ctx)
+{
+    if (ctx->cipher)
+    {
+        cipher_ctx_free(ctx->cipher);
+        ctx->cipher = NULL;
+    }
+    if (ctx->hmac)
+    {
+        hmac_ctx_cleanup(ctx->hmac);
+        hmac_ctx_free(ctx->hmac);
+        ctx->hmac = NULL;
+    }
+    ctx->implicit_iv_len = 0;
+}
+
+void
+free_key_ctx_bi(struct key_ctx_bi *ctx)
+{
+    free_key_ctx(&ctx->encrypt);
+    free_key_ctx(&ctx->decrypt);
+}
+
+static bool
+key_is_zero(struct key *key, const struct key_type *kt)
+{
+    int i;
+    for (i = 0; i < kt->cipher_length; ++i)
+        if (key->cipher[i])
+        {
+            return false;
+        }
+    msg(D_CRYPT_ERRORS, "CRYPTO INFO: WARNING: zero key detected");
+    return true;
+}
+
+/*
+ * Make sure that cipher key is a valid key for current key_type.
+ */
+bool
+check_key(struct key *key, const struct key_type *kt)
+{
+    if (kt->cipher)
+    {
+        /*
+         * Check for zero key
+         */
+        if (key_is_zero(key, kt))
+        {
+            return false;
+        }
+
+        /*
+         * Check for weak or semi-weak DES keys.
+         */
+        {
+            const int ndc = key_des_num_cblocks(kt->cipher);
+            if (ndc)
+            {
+                return key_des_check(key->cipher, kt->cipher_length, ndc);
+            }
+            else
+            {
+                return true;
+            }
+        }
+    }
+    return true;
+}
+
+/*
+ * Make safe mutations to key to ensure it is valid,
+ * such as ensuring correct parity on DES keys.
+ *
+ * This routine cannot guarantee it will generate a good
+ * key.  You must always call check_key after this routine
+ * to make sure.
+ */
+void
+fixup_key(struct key *key, const struct key_type *kt)
+{
+    struct gc_arena gc = gc_new();
+    if (kt->cipher)
+    {
+#ifdef ENABLE_DEBUG
+        const struct key orig = *key;
+#endif
+        const int ndc = key_des_num_cblocks(kt->cipher);
+
+        if (ndc)
+        {
+            key_des_fixup(key->cipher, kt->cipher_length, ndc);
+        }
+
+#ifdef ENABLE_DEBUG
+        if (check_debug_level(D_CRYPTO_DEBUG))
+        {
+            if (memcmp(orig.cipher, key->cipher, kt->cipher_length))
+            {
+                dmsg(D_CRYPTO_DEBUG, "CRYPTO INFO: fixup_key: before=%s after=%s",
+                     format_hex(orig.cipher, kt->cipher_length, 0, &gc),
+                     format_hex(key->cipher, kt->cipher_length, 0, &gc));
+            }
+        }
+#endif
+    }
+    gc_free(&gc);
+}
+
+void
+check_replay_iv_consistency(const struct key_type *kt, bool packet_id, bool use_iv)
+{
+    ASSERT(kt);
+
+    if (!(packet_id && use_iv) && (cipher_kt_mode_ofb_cfb(kt->cipher)
+                                   || cipher_kt_mode_aead(kt->cipher)))
+    {
+        msg(M_FATAL, "--no-replay or --no-iv cannot be used with a CFB, OFB or "
+            "AEAD mode cipher");
+    }
+}
+
+/*
+ * Generate a random key.  If key_type is provided, make
+ * sure generated key is valid for key_type.
+ */
+void
+generate_key_random(struct key *key, const struct key_type *kt)
+{
+    int cipher_len = MAX_CIPHER_KEY_LENGTH;
+    int hmac_len = MAX_HMAC_KEY_LENGTH;
+
+    struct gc_arena gc = gc_new();
+
+    do
+    {
+        CLEAR(*key);
+        if (kt)
+        {
+            if (kt->cipher && kt->cipher_length > 0 && kt->cipher_length <= cipher_len)
+            {
+                cipher_len = kt->cipher_length;
+            }
+
+            if (kt->digest && kt->hmac_length > 0 && kt->hmac_length <= hmac_len)
+            {
+                hmac_len = kt->hmac_length;
+            }
+        }
+        if (!rand_bytes(key->cipher, cipher_len)
+            || !rand_bytes(key->hmac, hmac_len))
+        {
+            msg(M_FATAL, "ERROR: Random number generator cannot obtain entropy for key generation");
+        }
+
+        dmsg(D_SHOW_KEY_SOURCE, "Cipher source entropy: %s", format_hex(key->cipher, cipher_len, 0, &gc));
+        dmsg(D_SHOW_KEY_SOURCE, "HMAC source entropy: %s", format_hex(key->hmac, hmac_len, 0, &gc));
+
+        if (kt)
+        {
+            fixup_key(key, kt);
+        }
+    } while (kt && !check_key(key, kt));
+
+    gc_free(&gc);
+}
+
+/*
+ * Print key material
+ */
+void
+key2_print(const struct key2 *k,
+           const struct key_type *kt,
+           const char *prefix0,
+           const char *prefix1)
+{
+    struct gc_arena gc = gc_new();
+    ASSERT(k->n == 2);
+    dmsg(D_SHOW_KEY_SOURCE, "%s (cipher): %s",
+         prefix0,
+         format_hex(k->keys[0].cipher, kt->cipher_length, 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE, "%s (hmac): %s",
+         prefix0,
+         format_hex(k->keys[0].hmac, kt->hmac_length, 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE, "%s (cipher): %s",
+         prefix1,
+         format_hex(k->keys[1].cipher, kt->cipher_length, 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE, "%s (hmac): %s",
+         prefix1,
+         format_hex(k->keys[1].hmac, kt->hmac_length, 0, &gc));
+    gc_free(&gc);
+}
+
+void
+test_crypto(struct crypto_options *co, struct frame *frame)
+{
+    int i, j;
+    struct gc_arena gc = gc_new();
+    struct buffer src = alloc_buf_gc(TUN_MTU_SIZE(frame), &gc);
+    struct buffer work = alloc_buf_gc(BUF_SIZE(frame), &gc);
+    struct buffer encrypt_workspace = alloc_buf_gc(BUF_SIZE(frame), &gc);
+    struct buffer decrypt_workspace = alloc_buf_gc(BUF_SIZE(frame), &gc);
+    struct buffer buf = clear_buf();
+    void *buf_p;
+
+    /* init work */
+    ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
+
+#ifdef HAVE_AEAD_CIPHER_MODES
+    /* init implicit IV */
+    {
+        const cipher_kt_t *cipher =
+            cipher_ctx_get_cipher_kt(co->key_ctx_bi.encrypt.cipher);
+
+        if (cipher_kt_mode_aead(cipher))
+        {
+            size_t impl_iv_len = cipher_kt_iv_size(cipher) - sizeof(packet_id_type);
+            ASSERT(cipher_kt_iv_size(cipher) <= OPENVPN_MAX_IV_LENGTH);
+            ASSERT(cipher_kt_iv_size(cipher) >= OPENVPN_AEAD_MIN_IV_LEN);
+
+            /* Generate dummy implicit IV */
+            ASSERT(rand_bytes(co->key_ctx_bi.encrypt.implicit_iv,
+                              OPENVPN_MAX_IV_LENGTH));
+            co->key_ctx_bi.encrypt.implicit_iv_len = impl_iv_len;
+
+            memcpy(co->key_ctx_bi.decrypt.implicit_iv,
+                   co->key_ctx_bi.encrypt.implicit_iv, OPENVPN_MAX_IV_LENGTH);
+            co->key_ctx_bi.decrypt.implicit_iv_len = impl_iv_len;
+        }
+    }
+#endif /* ifdef HAVE_AEAD_CIPHER_MODES */
+
+    msg(M_INFO, "Entering " PACKAGE_NAME " crypto self-test mode.");
+    for (i = 1; i <= TUN_MTU_SIZE(frame); ++i)
+    {
+        update_time();
+
+        msg(M_INFO, "TESTING ENCRYPT/DECRYPT of packet length=%d", i);
+
+        /*
+         * Load src with random data.
+         */
+        ASSERT(buf_init(&src, 0));
+        ASSERT(i <= src.capacity);
+        src.len = i;
+        ASSERT(rand_bytes(BPTR(&src), BLEN(&src)));
+
+        /* copy source to input buf */
+        buf = work;
+        buf_p = buf_write_alloc(&buf, BLEN(&src));
+        ASSERT(buf_p);
+        memcpy(buf_p, BPTR(&src), BLEN(&src));
+
+        /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+        ASSERT(buf_init(&encrypt_workspace, FRAME_HEADROOM(frame)));
+
+        /* encrypt */
+        openvpn_encrypt(&buf, encrypt_workspace, co);
+
+        /* decrypt */
+        openvpn_decrypt(&buf, decrypt_workspace, co, frame, BPTR(&buf));
+
+        /* compare */
+        if (buf.len != src.len)
+        {
+            msg(M_FATAL, "SELF TEST FAILED, src.len=%d buf.len=%d", src.len, buf.len);
+        }
+        for (j = 0; j < i; ++j)
+        {
+            const uint8_t in = *(BPTR(&src) + j);
+            const uint8_t out = *(BPTR(&buf) + j);
+            if (in != out)
+            {
+                msg(M_FATAL, "SELF TEST FAILED, pos=%d in=%d out=%d", j, in, out);
+            }
+        }
+    }
+    msg(M_INFO, PACKAGE_NAME " crypto self-test mode SUCCEEDED.");
+    gc_free(&gc);
+}
+
+void
+crypto_read_openvpn_key(const struct key_type *key_type,
+                        struct key_ctx_bi *ctx, const char *key_file, const char *key_inline,
+                        const int key_direction, const char *key_name, const char *opt_name)
+{
+    struct key2 key2;
+    struct key_direction_state kds;
+
+    if (key_inline)
+    {
+        read_key_file(&key2, key_inline, RKF_MUST_SUCCEED|RKF_INLINE);
+    }
+    else
+    {
+        read_key_file(&key2, key_file, RKF_MUST_SUCCEED);
+    }
+
+    if (key2.n != 2)
+    {
+        msg(M_ERR, "File '%s' does not have OpenVPN Static Key format.  Using "
+            "free-form passphrase file is not supported anymore.", key_file);
+    }
+
+    /* check for and fix highly unlikely key problems */
+    verify_fix_key2(&key2, key_type, key_file);
+
+    /* handle key direction */
+    key_direction_state_init(&kds, key_direction);
+    must_have_n_keys(key_file, opt_name, &key2, kds.need_keys);
+
+    /* initialize key in both directions */
+    init_key_ctx_bi(ctx, &key2, key_direction, key_type, key_name);
+    secure_memzero(&key2, sizeof(key2));
+}
+
+/* header and footer for static key file */
+static const char static_key_head[] = "-----BEGIN OpenVPN Static key V1-----";
+static const char static_key_foot[] = "-----END OpenVPN Static key V1-----";
+
+static const char printable_char_fmt[] =
+    "Non-Hex character ('%c') found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)";
+
+static const char unprintable_char_fmt[] =
+    "Non-Hex, unprintable character (0x%02x) found at line %d in key file '%s' (%d/%d/%d bytes found/min/max)";
+
+/* read key from file */
+
+void
+read_key_file(struct key2 *key2, const char *file, const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer in;
+    int fd, size;
+    uint8_t hex_byte[3] = {0, 0, 0};
+    const char *error_filename = file;
+
+    /* parse info */
+    const unsigned char *cp;
+    int hb_index = 0;
+    int line_num = 1;
+    int line_index = 0;
+    int match = 0;
+
+    /* output */
+    uint8_t *out = (uint8_t *) &key2->keys;
+    const int keylen = sizeof(key2->keys);
+    int count = 0;
+
+    /* parse states */
+#define PARSE_INITIAL        0
+#define PARSE_HEAD           1
+#define PARSE_DATA           2
+#define PARSE_DATA_COMPLETE  3
+#define PARSE_FOOT           4
+#define PARSE_FINISHED       5
+    int state = PARSE_INITIAL;
+
+    /* constants */
+    const int hlen = strlen(static_key_head);
+    const int flen = strlen(static_key_foot);
+    const int onekeylen = sizeof(key2->keys[0]);
+
+    CLEAR(*key2);
+
+    /*
+     * Key can be provided as a filename in 'file' or if RKF_INLINE
+     * is set, the actual key data itself in ascii form.
+     */
+    if (flags & RKF_INLINE) /* 'file' is a string containing ascii representation of key */
+    {
+        size = strlen(file) + 1;
+        buf_set_read(&in, (const uint8_t *)file, size);
+        error_filename = INLINE_FILE_TAG;
+    }
+    else /* 'file' is a filename which refers to a file containing the ascii key */
+    {
+        in = alloc_buf_gc(2048, &gc);
+        fd = platform_open(file, O_RDONLY, 0);
+        if (fd == -1)
+        {
+            msg(M_ERR, "Cannot open key file '%s'", file);
+        }
+        size = read(fd, in.data, in.capacity);
+        if (size < 0)
+        {
+            msg(M_FATAL, "Read error on key file ('%s')", file);
+        }
+        if (size == in.capacity)
+        {
+            msg(M_FATAL, "Key file ('%s') can be a maximum of %d bytes", file, (int)in.capacity);
+        }
+        close(fd);
+    }
+
+    cp = (unsigned char *)in.data;
+    while (size > 0)
+    {
+        const unsigned char c = *cp;
+
+#if 0
+        msg(M_INFO, "char='%c'[%d] s=%d ln=%d li=%d m=%d c=%d",
+            c, (int)c, state, line_num, line_index, match, count);
+#endif
+
+        if (c == '\n')
+        {
+            line_index = match = 0;
+            ++line_num;
+        }
+        else
+        {
+            /* first char of new line */
+            if (!line_index)
+            {
+                /* first char of line after header line? */
+                if (state == PARSE_HEAD)
+                {
+                    state = PARSE_DATA;
+                }
+
+                /* first char of footer */
+                if ((state == PARSE_DATA || state == PARSE_DATA_COMPLETE) && c == '-')
+                {
+                    state = PARSE_FOOT;
+                }
+            }
+
+            /* compare read chars with header line */
+            if (state == PARSE_INITIAL)
+            {
+                if (line_index < hlen && c == static_key_head[line_index])
+                {
+                    if (++match == hlen)
+                    {
+                        state = PARSE_HEAD;
+                    }
+                }
+            }
+
+            /* compare read chars with footer line */
+            if (state == PARSE_FOOT)
+            {
+                if (line_index < flen && c == static_key_foot[line_index])
+                {
+                    if (++match == flen)
+                    {
+                        state = PARSE_FINISHED;
+                    }
+                }
+            }
+
+            /* reading key */
+            if (state == PARSE_DATA)
+            {
+                if (isxdigit(c))
+                {
+                    ASSERT(hb_index >= 0 && hb_index < 2);
+                    hex_byte[hb_index++] = c;
+                    if (hb_index == 2)
+                    {
+                        unsigned int u;
+                        ASSERT(sscanf((const char *)hex_byte, "%x", &u) == 1);
+                        *out++ = u;
+                        hb_index = 0;
+                        if (++count == keylen)
+                        {
+                            state = PARSE_DATA_COMPLETE;
+                        }
+                    }
+                }
+                else if (isspace(c))
+                {
+                }
+                else
+                {
+                    msg(M_FATAL,
+                        (isprint(c) ? printable_char_fmt : unprintable_char_fmt),
+                        c, line_num, error_filename, count, onekeylen, keylen);
+                }
+            }
+            ++line_index;
+        }
+        ++cp;
+        --size;
+    }
+
+    /*
+     * Normally we will read either 1 or 2 keys from file.
+     */
+    key2->n = count / onekeylen;
+
+    ASSERT(key2->n >= 0 && key2->n <= (int) SIZE(key2->keys));
+
+    if (flags & RKF_MUST_SUCCEED)
+    {
+        if (!key2->n)
+        {
+            msg(M_FATAL, "Insufficient key material or header text not found in file '%s' (%d/%d/%d bytes found/min/max)",
+                error_filename, count, onekeylen, keylen);
+        }
+
+        if (state != PARSE_FINISHED)
+        {
+            msg(M_FATAL, "Footer text not found in file '%s' (%d/%d/%d bytes found/min/max)",
+                error_filename, count, onekeylen, keylen);
+        }
+    }
+
+    /* zero file read buffer if not an inline file */
+    if (!(flags & RKF_INLINE))
+    {
+        buf_clear(&in);
+    }
+
+#if 0
+    /* DEBUGGING */
+    {
+        int i;
+        printf("KEY READ, n=%d\n", key2->n);
+        for (i = 0; i < (int) SIZE(key2->keys); ++i)
+        {
+            /* format key as ascii */
+            const char *fmt = format_hex_ex((const uint8_t *)&key2->keys[i],
+                                            sizeof(key2->keys[i]),
+                                            0,
+                                            16,
+                                            "\n",
+                                            &gc);
+            printf("[%d]\n%s\n\n", i, fmt);
+        }
+    }
+#endif
+
+    /* pop our garbage collection level */
+    gc_free(&gc);
+}
+
+/*
+ * Write key to file, return number of random bits
+ * written.
+ */
+int
+write_key_file(const int nkeys, const char *filename)
+{
+    struct gc_arena gc = gc_new();
+
+    int fd, i;
+    int nbits = 0;
+
+    /* must be large enough to hold full key file */
+    struct buffer out = alloc_buf_gc(2048, &gc);
+    struct buffer nbits_head_text = alloc_buf_gc(128, &gc);
+
+    /* how to format the ascii file representation of key */
+    const int bytes_per_line = 16;
+
+    /* open key file */
+    fd = platform_open(filename, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR);
+
+    if (fd == -1)
+    {
+        msg(M_ERR, "Cannot open shared secret file '%s' for write", filename);
+    }
+
+    buf_printf(&out, "%s\n", static_key_head);
+
+    for (i = 0; i < nkeys; ++i)
+    {
+        struct key key;
+        char *fmt;
+
+        /* generate random bits */
+        generate_key_random(&key, NULL);
+
+        /* format key as ascii */
+        fmt = format_hex_ex((const uint8_t *)&key,
+                            sizeof(key),
+                            0,
+                            bytes_per_line,
+                            "\n",
+                            &gc);
+
+        /* increment random bits counter */
+        nbits += sizeof(key) * 8;
+
+        /* write to holding buffer */
+        buf_printf(&out, "%s\n", fmt);
+
+        /* zero memory which held key component (will be freed by GC) */
+        secure_memzero(fmt, strlen(fmt));
+        secure_memzero(&key, sizeof(key));
+    }
+
+    buf_printf(&out, "%s\n", static_key_foot);
+
+    /* write number of bits */
+    buf_printf(&nbits_head_text, "#\n# %d bit OpenVPN static key\n#\n", nbits);
+    buf_write_string_file(&nbits_head_text, filename, fd);
+
+    /* write key file, now formatted in out, to file */
+    buf_write_string_file(&out, filename, fd);
+
+    if (close(fd))
+    {
+        msg(M_ERR, "Close error on shared secret file %s", filename);
+    }
+
+    /* zero memory which held file content (memory will be freed by GC) */
+    buf_clear(&out);
+
+    /* pop our garbage collection level */
+    gc_free(&gc);
+
+    return nbits;
+}
+
+void
+must_have_n_keys(const char *filename, const char *option, const struct key2 *key2, int n)
+{
+    if (key2->n < n)
+    {
+#ifdef ENABLE_SMALL
+        msg(M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d]", filename, option, key2->n, n);
+#else
+        msg(M_FATAL, "Key file '%s' used in --%s contains insufficient key material [keys found=%d required=%d] -- try generating a new key file with '" PACKAGE " --genkey --secret [file]', or use the existing key file in bidirectional mode by specifying --%s without a key direction parameter", filename, option, key2->n, n, option);
+#endif
+    }
+}
+
+int
+ascii2keydirection(int msglevel, const char *str)
+{
+    if (!str)
+    {
+        return KEY_DIRECTION_BIDIRECTIONAL;
+    }
+    else if (!strcmp(str, "0"))
+    {
+        return KEY_DIRECTION_NORMAL;
+    }
+    else if (!strcmp(str, "1"))
+    {
+        return KEY_DIRECTION_INVERSE;
+    }
+    else
+    {
+        msg(msglevel, "Unknown key direction '%s' -- must be '0' or '1'", str);
+        return -1;
+    }
+    return KEY_DIRECTION_BIDIRECTIONAL; /* NOTREACHED */
+}
+
+const char *
+keydirection2ascii(int kd, bool remote, bool humanreadable)
+{
+    if (kd == KEY_DIRECTION_BIDIRECTIONAL)
+    {
+        if (humanreadable)
+        {
+            return "not set";
+        }
+        else
+        {
+            return NULL;
+        }
+    }
+    else if (kd == KEY_DIRECTION_NORMAL)
+    {
+        return remote ? "1" : "0";
+    }
+    else if (kd == KEY_DIRECTION_INVERSE)
+    {
+        return remote ? "0" : "1";
+    }
+    else
+    {
+        ASSERT(0);
+    }
+    return NULL; /* NOTREACHED */
+}
+
+void
+key_direction_state_init(struct key_direction_state *kds, int key_direction)
+{
+    CLEAR(*kds);
+    switch (key_direction)
+    {
+        case KEY_DIRECTION_NORMAL:
+            kds->out_key = 0;
+            kds->in_key = 1;
+            kds->need_keys = 2;
+            break;
+
+        case KEY_DIRECTION_INVERSE:
+            kds->out_key = 1;
+            kds->in_key = 0;
+            kds->need_keys = 2;
+            break;
+
+        case KEY_DIRECTION_BIDIRECTIONAL:
+            kds->out_key = 0;
+            kds->in_key = 0;
+            kds->need_keys = 1;
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+void
+verify_fix_key2(struct key2 *key2, const struct key_type *kt, const char *shared_secret_file)
+{
+    int i;
+
+    for (i = 0; i < key2->n; ++i)
+    {
+        /* Fix parity for DES keys and make sure not a weak key */
+        fixup_key(&key2->keys[i], kt);
+
+        /* This should be a very improbable failure */
+        if (!check_key(&key2->keys[i], kt))
+        {
+            msg(M_FATAL, "Key #%d in '%s' is bad.  Try making a new key with --genkey.",
+                i+1, shared_secret_file);
+        }
+    }
+}
+
+/* given a key and key_type, write key to buffer */
+bool
+write_key(const struct key *key, const struct key_type *kt,
+          struct buffer *buf)
+{
+    ASSERT(kt->cipher_length <= MAX_CIPHER_KEY_LENGTH
+           && kt->hmac_length <= MAX_HMAC_KEY_LENGTH);
+
+    if (!buf_write(buf, &kt->cipher_length, 1))
+    {
+        return false;
+    }
+    if (!buf_write(buf, &kt->hmac_length, 1))
+    {
+        return false;
+    }
+    if (!buf_write(buf, key->cipher, kt->cipher_length))
+    {
+        return false;
+    }
+    if (!buf_write(buf, key->hmac, kt->hmac_length))
+    {
+        return false;
+    }
+
+    return true;
+}
+
+/*
+ * Given a key_type and buffer, read key from buffer.
+ * Return: 1 on success
+ *        -1 read failure
+ *         0 on key length mismatch
+ */
+int
+read_key(struct key *key, const struct key_type *kt, struct buffer *buf)
+{
+    uint8_t cipher_length;
+    uint8_t hmac_length;
+
+    CLEAR(*key);
+    if (!buf_read(buf, &cipher_length, 1))
+    {
+        goto read_err;
+    }
+    if (!buf_read(buf, &hmac_length, 1))
+    {
+        goto read_err;
+    }
+
+    if (cipher_length != kt->cipher_length || hmac_length != kt->hmac_length)
+    {
+        goto key_len_err;
+    }
+
+    if (!buf_read(buf, key->cipher, cipher_length))
+    {
+        goto read_err;
+    }
+    if (!buf_read(buf, key->hmac, hmac_length))
+    {
+        goto read_err;
+    }
+
+    return 1;
+
+read_err:
+    msg(D_TLS_ERRORS, "TLS Error: error reading key from remote");
+    return -1;
+
+key_len_err:
+    msg(D_TLS_ERRORS,
+        "TLS Error: key length mismatch, local cipher/hmac %d/%d, remote cipher/hmac %d/%d",
+        kt->cipher_length, kt->hmac_length, cipher_length, hmac_length);
+    return 0;
+}
+
+/*
+ * Random number functions, used in cases where we want
+ * reasonably strong cryptographic random number generation
+ * without depleting our entropy pool.  Used for random
+ * IV values and a number of other miscellaneous tasks.
+ */
+
+static uint8_t *nonce_data = NULL; /* GLOBAL */
+static const md_kt_t *nonce_md = NULL; /* GLOBAL */
+static int nonce_secret_len = 0; /* GLOBAL */
+
+/* Reset the nonce value, also done periodically to refresh entropy */
+static void
+prng_reset_nonce(void)
+{
+    const int size = md_kt_size(nonce_md) + nonce_secret_len;
+#if 1 /* Must be 1 for real usage */
+    if (!rand_bytes(nonce_data, size))
+    {
+        msg(M_FATAL, "ERROR: Random number generator cannot obtain entropy for PRNG");
+    }
+#else
+    /* Only for testing -- will cause a predictable PRNG sequence */
+    {
+        int i;
+        for (i = 0; i < size; ++i)
+            nonce_data[i] = (uint8_t) i;
+    }
+#endif
+}
+
+void
+prng_init(const char *md_name, const int nonce_secret_len_parm)
+{
+    prng_uninit();
+    nonce_md = md_name ? md_kt_get(md_name) : NULL;
+    if (nonce_md)
+    {
+        ASSERT(nonce_secret_len_parm >= NONCE_SECRET_LEN_MIN && nonce_secret_len_parm <= NONCE_SECRET_LEN_MAX);
+        nonce_secret_len = nonce_secret_len_parm;
+        {
+            const int size = md_kt_size(nonce_md) + nonce_secret_len;
+            dmsg(D_CRYPTO_DEBUG, "PRNG init md=%s size=%d", md_kt_name(nonce_md), size);
+            nonce_data = (uint8_t *) malloc(size);
+            check_malloc_return(nonce_data);
+            prng_reset_nonce();
+        }
+    }
+}
+
+void
+prng_uninit(void)
+{
+    free(nonce_data);
+    nonce_data = NULL;
+    nonce_md = NULL;
+    nonce_secret_len = 0;
+}
+
+void
+prng_bytes(uint8_t *output, int len)
+{
+    static size_t processed = 0;
+
+    if (nonce_md)
+    {
+        const int md_size = md_kt_size(nonce_md);
+        while (len > 0)
+        {
+            const int blen = min_int(len, md_size);
+            md_full(nonce_md, nonce_data, md_size + nonce_secret_len, nonce_data);
+            memcpy(output, nonce_data, blen);
+            output += blen;
+            len -= blen;
+
+            /* Ensure that random data is reset regularly */
+            processed += blen;
+            if (processed > PRNG_NONCE_RESET_BYTES)
+            {
+                prng_reset_nonce();
+                processed = 0;
+            }
+        }
+    }
+    else
+    {
+        ASSERT(rand_bytes(output, len));
+    }
+}
+
+/* an analogue to the random() function, but use prng_bytes */
+long int
+get_random(void)
+{
+    long int l;
+    prng_bytes((unsigned char *)&l, sizeof(l));
+    if (l < 0)
+    {
+        l = -l;
+    }
+    return l;
+}
+
+static const cipher_name_pair *
+get_cipher_name_pair(const char *cipher_name)
+{
+    const cipher_name_pair *pair;
+    size_t i = 0;
+
+    /* Search for a cipher name translation */
+    for (; i < cipher_name_translation_table_count; i++)
+    {
+        pair = &cipher_name_translation_table[i];
+        if (0 == strcmp(cipher_name, pair->openvpn_name)
+            || 0 == strcmp(cipher_name, pair->lib_name))
+        {
+            return pair;
+        }
+    }
+
+    /* Nothing found, return null */
+    return NULL;
+}
+
+const char *
+translate_cipher_name_from_openvpn(const char *cipher_name)
+{
+    const cipher_name_pair *pair = get_cipher_name_pair(cipher_name);
+
+    if (NULL == pair)
+    {
+        return cipher_name;
+    }
+
+    return pair->lib_name;
+}
+
+const char *
+translate_cipher_name_to_openvpn(const char *cipher_name)
+{
+    const cipher_name_pair *pair = get_cipher_name_pair(cipher_name);
+
+    if (NULL == pair)
+    {
+        return cipher_name;
+    }
+
+    return pair->openvpn_name;
+}
+
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/crypto.h b/src/openvpn/crypto.h
new file mode 100644
index 0000000..185bfd3
--- /dev/null
+++ b/src/openvpn/crypto.h
@@ -0,0 +1,524 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography Module
+ *
+ * @addtogroup data_crypto Data Channel Crypto module
+ *
+ * @par Crypto packet formats
+ * The Data Channel Crypto module supports a number of crypto modes and
+ * configurable options. The actual packet format depends on these options. A
+ * Data Channel packet can consist of:
+ *  - \b Opcode, one byte specifying the packet type (see @ref network_protocol
+ *    "Network protocol").
+ *  - \b Peer-id, if using the v2 data channel packet format (see @ref
+ *    network_protocol "Network protocol").
+ *  - \b HMAC, covering the ciphertext IV + ciphertext. The HMAC size depends
+ *    on the \c \-\-auth option. If \c \-\-auth \c none is specified, there is no
+ *    HMAC at all.
+ *  - \b Ciphertext \b IV, if not disabled by \c \-\-no-iv. The IV size depends on
+ *    the \c \-\-cipher option.
+ *  - \b Packet \b ID, a 32-bit incrementing packet counter that provides replay
+ *    protection (if not disabled by \c \-\-no-replay).
+ *  - \b Timestamp, a 32-bit timestamp of the current time.
+ *  - \b Payload, the plain text network packet to be encrypted (unless
+ *    encryption is disabled by using \c \-\-cipher \c none). The payload might
+ *    already be compressed (see @ref compression "Compression module").
+ *
+ * @par
+ * This section does not discuss the opcode and peer-id, since those do not
+ * depend on the data channel crypto. See @ref network_protocol
+ * "Network protocol" for more information on those.
+ *
+ * @par
+ * \e Legenda \n
+ * <tt>[ xxx ]</tt> = unprotected \n
+ * <tt>[ - xxx - ]</tt> = authenticated \n
+ * <tt>[ * xxx * ]</tt> = encrypted and authenticated
+ *
+ * @par
+ * <b>CBC data channel cypto format</b> \n
+ * In CBC mode, both TLS-mode and static key mode are supported. The IV
+ * consists of random bits to provide unpredictable IVs. \n
+ * <i>CBC IV format:</i> \n
+ * <tt> [ - random - ] </tt> \n
+ * <i>CBC data channel crypto format in TLS-mode:</i> \n
+ * <tt> [ HMAC ] [ - IV - ] [ * packet ID * ] [ * packet payload * ] </tt> \n
+ * <i>CBC data channel crypto format in static key mode:</i> \n
+ * <tt> [ HMAC ] [ - IV - ] [ * packet ID * ] [ * timestamp * ]
+ * [ * packet payload * ] </tt>
+ *
+ * @par
+ * <b>CFB/OFB data channel crypto format</b> \n
+ * CFB and OFB modes are only supported in TLS mode. In these modes, the IV
+ * consists of the packet counter and a timestamp. If the IV is more than 8
+ * bytes long, the remaining space is filled with zeroes. The packet counter may
+ * not roll over within a single TLS sessions. This results in a unique IV for
+ * each packet, as required by the CFB and OFB cipher modes.
+ *
+ * @par
+ * <i>CFB/OFB IV format:</i> \n
+ * <tt>   [ - packet ID - ] [ - timestamp - ] [ - opt: zero-padding - ] </tt>\n
+ * <i>CFB/OFB data channel crypto format:</i> \n
+ * <tt>   [ HMAC ] [ - IV - ] [ * packet payload * ] </tt>
+ *
+ * @par
+ * <b>GCM data channel crypto format</b> \n
+ * GCM modes are only supported in TLS mode.  In these modes, the IV consists of
+ * the 32-bit packet counter followed by data from the HMAC key.  The HMAC key
+ * can be used as IV, since in GCM and CCM modes the HMAC key is not used for
+ * the HMAC.  The packet counter may not roll over within a single TLS sessions.
+ * This results in a unique IV for each packet, as required by GCM.
+ *
+ * @par
+ * The HMAC key data is pre-shared during the connection setup, and thus can be
+ * omitted in on-the-wire packets, saving 8 bytes per packet (for GCM and CCM).
+ *
+ * @par
+ * In GCM mode, P_DATA_V2 headers (the opcode and peer-id) are also
+ * authenticated as Additional Data.
+ *
+ * @par
+ * <i>GCM IV format:</i> \n
+ * <tt>   [ - packet ID - ] [ - HMAC key data - ] </tt>\n
+ * <i>P_DATA_V1 GCM data channel crypto format:</i> \n
+ * <tt>   [ opcode ] [ - packet ID - ] [ TAG ] [ * packet payload * ] </tt>
+ * <i>P_DATA_V2 GCM data channel crypto format:</i> \n
+ * <tt>   [ - opcode/peer-id - ] [ - packet ID - ] [ TAG ] [ * packet payload * ] </tt>
+ *
+ * @par
+ * <b>No-crypto data channel format</b> \n
+ * In no-crypto mode (\c \-\-cipher \c none is specified), both TLS-mode and
+ * static key mode are supported. No encryption will be performed on the packet,
+ * but packets can still be authenticated. This mode does not require an IV.\n
+ * <i>No-crypto data channel crypto format in TLS-mode:</i> \n
+ * <tt> [ HMAC ] [ - packet ID - ] [ - packet payload - ] </tt> \n
+ * <i>No-crypto data channel crypto format in static key mode:</i> \n
+ * <tt> [ HMAC ] [ - packet ID - ] [ - timestamp - ] [ - packet payload - ] </tt>
+ *
+ */
+
+#ifndef CRYPTO_H
+#define CRYPTO_H
+
+#ifdef ENABLE_CRYPTO
+
+#include "crypto_backend.h"
+#include "basic.h"
+#include "buffer.h"
+#include "packet_id.h"
+#include "mtu.h"
+
+/** Wrapper struct to pass around SHA256 digests */
+struct sha256_digest {
+    uint8_t digest[SHA256_DIGEST_LENGTH];
+};
+
+/*
+ * Defines a key type and key length for both cipher and HMAC.
+ */
+struct key_type
+{
+    uint8_t cipher_length;      /**< Cipher length, in bytes */
+    uint8_t hmac_length;        /**< HMAC length, in bytes */
+    const cipher_kt_t *cipher;  /**< Cipher static parameters */
+    const md_kt_t *digest;      /**< Message digest static parameters */
+};
+
+/**
+ * Container for unidirectional cipher and HMAC %key material.
+ * @ingroup control_processor
+ */
+struct key
+{
+    uint8_t cipher[MAX_CIPHER_KEY_LENGTH];
+    /**< %Key material for cipher operations. */
+    uint8_t hmac[MAX_HMAC_KEY_LENGTH];
+    /**< %Key material for HMAC operations. */
+};
+
+
+/**
+ * Container for one set of cipher and/or HMAC contexts.
+ * @ingroup control_processor
+ */
+struct key_ctx
+{
+    cipher_ctx_t *cipher;       /**< Generic cipher %context. */
+    hmac_ctx_t *hmac;           /**< Generic HMAC %context. */
+    uint8_t implicit_iv[OPENVPN_MAX_IV_LENGTH];
+    /**< The implicit part of the IV */
+    size_t implicit_iv_len;     /**< The length of implicit_iv */
+};
+
+#define KEY_DIRECTION_BIDIRECTIONAL 0 /* same keys for both directions */
+#define KEY_DIRECTION_NORMAL        1 /* encrypt with keys[0], decrypt with keys[1] */
+#define KEY_DIRECTION_INVERSE       2 /* encrypt with keys[1], decrypt with keys[0] */
+
+/**
+ * Container for bidirectional cipher and HMAC %key material.
+ * @ingroup control_processor
+ */
+struct key2
+{
+    int n;                      /**< The number of \c key objects stored
+                                 *   in the \c key2.keys array. */
+    struct key keys[2];         /**< Two unidirectional sets of %key
+                                 *   material. */
+};
+
+/**
+ * %Key ordering of the \c key2.keys array.
+ * @ingroup control_processor
+ *
+ * This structure takes care of correct ordering when using unidirectional
+ * or bidirectional %key material, and allows the same shared secret %key
+ * file to be loaded in the same way by client and server by having one of
+ * the hosts use an reversed ordering.
+ */
+struct key_direction_state
+{
+    int out_key;                /**< Index into the \c key2.keys array for
+                                 *   the sending direction. */
+    int in_key;                 /**< Index into the \c key2.keys array for
+                                 *   the receiving direction. */
+    int need_keys;              /**< The number of key objects necessary
+                                 *   to support both sending and
+                                 *   receiving.
+                                 *
+                                 *   This will be 1 if the same keys are
+                                 *   used in both directions, or 2 if
+                                 *   there are two sets of unidirectional
+                                 *   keys. */
+};
+
+/**
+ * Container for two sets of OpenSSL cipher and/or HMAC contexts for both
+ * sending and receiving directions.
+ * @ingroup control_processor
+ */
+struct key_ctx_bi
+{
+    struct key_ctx encrypt;     /**< Cipher and/or HMAC contexts for sending
+                                 *   direction. */
+    struct key_ctx decrypt;     /**< cipher and/or HMAC contexts for
+                                 *   receiving direction. */
+    bool initialized;
+};
+
+/**
+ * Security parameter state for processing data channel packets.
+ * @ingroup data_crypto
+ */
+struct crypto_options
+{
+    struct key_ctx_bi key_ctx_bi;
+    /**< OpenSSL cipher and HMAC contexts for
+     *   both sending and receiving
+     *   directions. */
+    struct packet_id packet_id; /**< Current packet ID state for both
+                                 *   sending and receiving directions. */
+    struct packet_id_persist *pid_persist;
+    /**< Persistent packet ID state for
+     *   keeping state between successive
+     *   OpenVPN process startups. */
+
+#define CO_PACKET_ID_LONG_FORM  (1<<0)
+    /**< Bit-flag indicating whether to use
+    *   OpenVPN's long packet ID format. */
+#define CO_USE_IV               (1<<1)
+    /**< Bit-flag indicating whether to
+     *   generate a pseudo-random IV for each
+     *   packet being encrypted. */
+#define CO_IGNORE_PACKET_ID     (1<<2)
+    /**< Bit-flag indicating whether to ignore
+     *   the packet ID of a received packet.
+     *   This flag is used during processing
+     *   of the first packet received from a
+     *   client. */
+#define CO_MUTE_REPLAY_WARNINGS (1<<3)
+    /**< Bit-flag indicating not to display
+     *   replay warnings. */
+    unsigned int flags;         /**< Bit-flags determining behavior of
+                                 *   security operation functions. */
+};
+
+#define CRYPT_ERROR(format) \
+    do { msg(D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false)
+
+/**
+ * Minimal IV length for AEAD mode ciphers (in bytes):
+ * 4-byte packet id + 8 bytes implicit IV.
+ */
+#define OPENVPN_AEAD_MIN_IV_LEN (sizeof(packet_id_type) + 8)
+
+#define RKF_MUST_SUCCEED (1<<0)
+#define RKF_INLINE       (1<<1)
+void read_key_file(struct key2 *key2, const char *file, const unsigned int flags);
+
+int write_key_file(const int nkeys, const char *filename);
+
+int read_passphrase_hash(const char *passphrase_file,
+                         const md_kt_t *digest,
+                         uint8_t *output,
+                         int len);
+
+void generate_key_random(struct key *key, const struct key_type *kt);
+
+void check_replay_iv_consistency(const struct key_type *kt, bool packet_id, bool use_iv);
+
+bool check_key(struct key *key, const struct key_type *kt);
+
+void fixup_key(struct key *key, const struct key_type *kt);
+
+bool write_key(const struct key *key, const struct key_type *kt,
+               struct buffer *buf);
+
+int read_key(struct key *key, const struct key_type *kt, struct buffer *buf);
+
+/**
+ * Initialize a key_type structure with.
+ *
+ * @param kt          The struct key_type to initialize
+ * @param ciphername  The name of the cipher to use
+ * @param authname    The name of the HMAC digest to use
+ * @param keysize     The length of the cipher key to use, in bytes.  Only valid
+ *                    for ciphers that support variable length keys.
+ * @param tls_mode    Specifies wether we are running in TLS mode, which allows
+ *                    more ciphers than static key mode.
+ * @param warn        Print warnings when null cipher / auth is used.
+ */
+void init_key_type(struct key_type *kt, const char *ciphername,
+                   const char *authname, int keysize, bool tls_mode, bool warn);
+
+/*
+ * Key context functions
+ */
+
+void init_key_ctx(struct key_ctx *ctx, const struct key *key,
+                  const struct key_type *kt, int enc,
+                  const char *prefix);
+
+void free_key_ctx(struct key_ctx *ctx);
+
+void init_key_ctx_bi(struct key_ctx_bi *ctx, const struct key2 *key2,
+                     int key_direction, const struct key_type *kt,
+		     const char *name);
+
+void free_key_ctx_bi(struct key_ctx_bi *ctx);
+
+
+/**************************************************************************/
+/** @name Functions for performing security operations on data channel packets
+ *  @{ */
+
+/**
+ * Encrypt and HMAC sign a packet so that it can be sent as a data channel
+ * VPN tunnel packet to a remote OpenVPN peer.
+ * @ingroup data_crypto
+ *
+ * This function handles encryption and HMAC signing of a data channel
+ * packet before it is sent to its remote OpenVPN peer.  It receives the
+ * necessary security parameters in the \a opt argument, which should have
+ * been set to the correct values by the \c tls_pre_encrypt() function.
+ *
+ * This function calls the \c EVP_Cipher* and \c HMAC_* functions of the
+ * OpenSSL library to perform the actual security operations.
+ *
+ * If an error occurs during processing, then the \a buf %buffer is set to
+ * empty.
+ *
+ * @param buf          - The %buffer containing the packet on which to
+ *                       perform security operations.
+ * @param work         - An initialized working %buffer.
+ * @param opt          - The security parameter state for this VPN tunnel.
+ *
+ * @return This function returns void.\n On return, the \a buf argument
+ *     will point to the resulting %buffer.  This %buffer will either
+ *     contain the processed packet ready for sending, or be empty if an
+ *     error occurred.
+ */
+void openvpn_encrypt(struct buffer *buf, struct buffer work,
+                     struct crypto_options *opt);
+
+
+/**
+ * HMAC verify and decrypt a data channel packet received from a remote
+ * OpenVPN peer.
+ * @ingroup data_crypto
+ *
+ * This function handles authenticating and decrypting a data channel
+ * packet received from a remote OpenVPN peer.  It receives the necessary
+ * security parameters in the \a opt argument, which should have been set
+ * to the correct values by the \c tls_pre_decrypt() function.
+ *
+ * This function calls the \c EVP_Cipher* and \c HMAC_* functions of the
+ * OpenSSL library to perform the actual security operations.
+ *
+ * If an error occurs during processing, then the \a buf %buffer is set to
+ * empty.
+ *
+ * @param buf          - The %buffer containing the packet received from a
+ *                       remote OpenVPN peer on which to perform security
+ *                       operations.
+ * @param work         - A working %buffer.
+ * @param opt          - The security parameter state for this VPN tunnel.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel.
+ * @param ad_start     - A pointer into buf, indicating from where to start
+ *                       authenticating additional data (AEAD mode only).
+ *
+ * @return
+ * @li True, if the packet was authenticated and decrypted successfully.
+ * @li False, if an error occurred. \n On return, the \a buf argument will
+ *     point to the resulting %buffer.  This %buffer will either contain
+ *     the plaintext packet ready for further processing, or be empty if
+ *     an error occurred.
+ */
+bool openvpn_decrypt(struct buffer *buf, struct buffer work,
+                     struct crypto_options *opt, const struct frame *frame,
+                     const uint8_t *ad_start);
+
+/** @} name Functions for performing security operations on data channel packets */
+
+/**
+ * Check packet ID for replay, and perform replay administration.
+ *
+ * @param opt   Crypto options for this packet, contains replay state.
+ * @param pin   Packet ID read from packet.
+ * @param error_prefix  Prefix to use when printing error messages.
+ * @param gc    Garbage collector to use.
+ *
+ * @return true if packet ID is validated to be not a replay, false otherwise.
+ */
+bool crypto_check_replay(struct crypto_options *opt,
+                         const struct packet_id_net *pin, const char *error_prefix,
+                         struct gc_arena *gc);
+
+
+/** Calculate crypto overhead and adjust frame to account for that */
+void crypto_adjust_frame_parameters(struct frame *frame,
+                                    const struct key_type *kt,
+                                    bool use_iv,
+                                    bool packet_id,
+                                    bool packet_id_long_form);
+
+/** Return the worst-case OpenVPN crypto overhead (in bytes) */
+unsigned int crypto_max_overhead(void);
+
+/* Minimum length of the nonce used by the PRNG */
+#define NONCE_SECRET_LEN_MIN 16
+
+/* Maximum length of the nonce used by the PRNG */
+#define NONCE_SECRET_LEN_MAX 64
+
+/** Number of bytes of random to allow before resetting the nonce */
+#define PRNG_NONCE_RESET_BYTES 1024
+
+/**
+ * Pseudo-random number generator initialisation.
+ * (see \c prng_rand_bytes())
+ *
+ * @param md_name                       Name of the message digest to use
+ * @param nonce_secret_len_param        Length of the nonce to use
+ */
+void prng_init(const char *md_name, const int nonce_secret_len_parm);
+
+/*
+ * Message digest-based pseudo random number generator.
+ *
+ * If the PRNG was initialised with a certain message digest, uses the digest
+ * to calculate the next random number, and prevent depletion of the entropy
+ * pool.
+ *
+ * This PRNG is aimed at IV generation and similar miscellaneous tasks. Use
+ * \c rand_bytes() for higher-assurance functionality.
+ *
+ * Retrieves len bytes of pseudo random data, and places it in output.
+ *
+ * @param output        Output buffer
+ * @param len           Length of the output buffer
+ */
+void prng_bytes(uint8_t *output, int len);
+
+void prng_uninit(void);
+
+void test_crypto(struct crypto_options *co, struct frame *f);
+
+
+/* key direction functions */
+
+void key_direction_state_init(struct key_direction_state *kds, int key_direction);
+
+void verify_fix_key2(struct key2 *key2, const struct key_type *kt, const char *shared_secret_file);
+
+void must_have_n_keys(const char *filename, const char *option, const struct key2 *key2, int n);
+
+int ascii2keydirection(int msglevel, const char *str);
+
+const char *keydirection2ascii(int kd, bool remote, bool humanreadable);
+
+/* print keys */
+void key2_print(const struct key2 *k,
+                const struct key_type *kt,
+                const char *prefix0,
+                const char *prefix1);
+
+void crypto_read_openvpn_key(const struct key_type *key_type,
+                             struct key_ctx_bi *ctx, const char *key_file, const char *key_inline,
+                             const int key_direction, const char *key_name, const char *opt_name);
+
+/*
+ * Inline functions
+ */
+
+/**
+ * As memcmp(), but constant-time.
+ * Returns 0 when data is equal, non-zero otherwise.
+ */
+static inline int
+memcmp_constant_time(const void *a, const void *b, size_t size)
+{
+    const uint8_t *a1 = a;
+    const uint8_t *b1 = b;
+    int ret = 0;
+    size_t i;
+
+    for (i = 0; i < size; i++) {
+        ret |= *a1++ ^ *b1++;
+    }
+
+    return ret;
+}
+
+static inline bool
+key_ctx_bi_defined(const struct key_ctx_bi *key)
+{
+    return key->encrypt.cipher || key->encrypt.hmac || key->decrypt.cipher || key->decrypt.hmac;
+}
+
+
+#endif /* ENABLE_CRYPTO */
+#endif /* CRYPTO_H */
diff --git a/src/openvpn/crypto_backend.h b/src/openvpn/crypto_backend.h
new file mode 100644
index 0000000..b3db925
--- /dev/null
+++ b/src/openvpn/crypto_backend.h
@@ -0,0 +1,665 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography SSL library-specific backend interface
+ */
+
+#ifndef CRYPTO_BACKEND_H_
+#define CRYPTO_BACKEND_H_
+
+#ifdef ENABLE_CRYPTO_OPENSSL
+#include "crypto_openssl.h"
+#endif
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include "crypto_mbedtls.h"
+#endif
+#include "basic.h"
+
+/* TLS uses a tag of 128 bytes, let's do the same for OpenVPN */
+#define OPENVPN_AEAD_TAG_LENGTH 16
+
+/* Maximum cipher block size (bytes) */
+#define OPENVPN_MAX_CIPHER_BLOCK_SIZE 32
+
+/* Maximum HMAC digest size (bytes) */
+#define OPENVPN_MAX_HMAC_SIZE   64
+
+/** Types referencing specific message digest hashing algorithms */
+typedef enum {
+    MD_SHA1,
+    MD_SHA256
+} hash_algo_type ;
+
+/** Struct used in cipher name translation table */
+typedef struct {
+    const char *openvpn_name;   /**< Cipher name used by OpenVPN */
+    const char *lib_name;       /**< Cipher name used by crypto library */
+} cipher_name_pair;
+
+/** Cipher name translation table */
+extern const cipher_name_pair cipher_name_translation_table[];
+extern const size_t cipher_name_translation_table_count;
+
+/*
+ * This routine should have additional OpenSSL crypto library initialisations
+ * used by both crypto and ssl components of OpenVPN.
+ */
+void crypto_init_lib(void);
+
+void crypto_uninit_lib(void);
+
+void crypto_clear_error(void);
+
+/*
+ * Initialise the given named crypto engine.
+ */
+void crypto_init_lib_engine(const char *engine_name);
+
+#ifdef DMALLOC
+/*
+ * OpenSSL memory debugging.  If dmalloc debugging is enabled, tell
+ * OpenSSL to use our private malloc/realloc/free functions so that
+ * we can dispatch them to dmalloc.
+ */
+void crypto_init_dmalloc(void);
+
+#endif /* DMALLOC */
+
+/**
+ * Translate a data channel cipher name from the OpenVPN config file
+ * 'language' to the crypto library specific name.
+ */
+const char *translate_cipher_name_from_openvpn(const char *cipher_name);
+
+/**
+ * Translate a data channel cipher name from the crypto library specific name
+ * to the OpenVPN config file 'language'.
+ */
+const char *translate_cipher_name_from_openvpn(const char *cipher_name);
+
+void show_available_ciphers(void);
+
+void show_available_digests(void);
+
+void show_available_engines(void);
+
+/*
+ *
+ * Random number functions, used in cases where we want
+ * reasonably strong cryptographic random number generation
+ * without depleting our entropy pool.  Used for random
+ * IV values and a number of other miscellaneous tasks.
+ *
+ */
+
+/**
+ * Wrapper for secure random number generator. Retrieves len bytes of random
+ * data, and places it in output.
+ *
+ * @param output        Output buffer
+ * @param len           Length of the output buffer, in bytes
+ *
+ * @return              \c 1 on success, \c 0 on failure
+ */
+int rand_bytes(uint8_t *output, int len);
+
+/*
+ *
+ * Key functions, allow manipulation of keys.
+ *
+ */
+
+
+/**
+ * Return number of DES cblocks (1 cblock = length of a single-DES key) for the
+ * current key type or 0 if not a DES cipher.
+ *
+ * @param kt            Type of key
+ *
+ * @return              Number of DES cblocks that the key consists of, or 0.
+ */
+int key_des_num_cblocks(const cipher_kt_t *kt);
+
+/*
+ * Check the given DES key. Checks the given key's length, weakness and parity.
+ *
+ * @param key           Key to check
+ * @param key_len       Length of the key, in bytes
+ * @param ndc           Number of DES cblocks that the key is made up of.
+ *
+ * @return              \c true if the key is valid, \c false otherwise.
+ */
+bool key_des_check(uint8_t *key, int key_len, int ndc);
+
+/*
+ * Fix the given DES key, setting its parity to odd.
+ *
+ * @param key           Key to check
+ * @param key_len       Length of the key, in bytes
+ * @param ndc           Number of DES cblocks that the key is made up of.
+ */
+void key_des_fixup(uint8_t *key, int key_len, int ndc);
+
+/**
+ * Encrypt the given block, using DES ECB mode
+ *
+ * @param key           DES key to use.
+ * @param src           Buffer containing the 8-byte source.
+ * @param dst           Buffer containing the 8-byte destination
+ */
+void cipher_des_encrypt_ecb(const unsigned char key[DES_KEY_LENGTH],
+                            unsigned char src[DES_KEY_LENGTH],
+                            unsigned char dst[DES_KEY_LENGTH]);
+
+/*
+ *
+ * Generic cipher key type functions
+ *
+ */
+/*
+ * Max size in bytes of any cipher key that might conceivably be used.
+ *
+ * This value is checked at compile time in crypto.c to make sure
+ * it is always at least EVP_MAX_KEY_LENGTH.
+ *
+ * We define our own value, since this parameter
+ * is used to control the size of static key files.
+ * If the OpenSSL library increases EVP_MAX_KEY_LENGTH,
+ * we don't want our key files to be suddenly rendered
+ * unusable.
+ */
+#define MAX_CIPHER_KEY_LENGTH 64
+
+/**
+ * Return cipher parameters, based on the given cipher name. The
+ * contents of these parameters are library-specific, and can be used to
+ * initialise encryption/decryption.
+ *
+ * @param ciphername    Name of the cipher to retrieve parameters for (e.g.
+ *                      \c AES-128-CBC).
+ *
+ * @return              A statically allocated structure containing parameters
+ *                      for the given cipher, or NULL if no matching parameters
+ *                      were found.
+ */
+const cipher_kt_t *cipher_kt_get(const char *ciphername);
+
+/**
+ * Retrieve a string describing the cipher (e.g. \c AES-128-CBC).
+ *
+ * @param cipher_kt     Static cipher parameters
+ *
+ * @return a statically allocated string describing the cipher.
+ */
+const char *cipher_kt_name(const cipher_kt_t *cipher_kt);
+
+/**
+ * Returns the size of keys used by the cipher, in bytes. If the cipher has a
+ * variable key size, return the default key size.
+ *
+ * @param cipher_kt     Static cipher parameters
+ *
+ * @return              (Default) size of keys used by the cipher, in bytes.
+ */
+int cipher_kt_key_size(const cipher_kt_t *cipher_kt);
+
+/**
+ * Returns the size of the IV used by the cipher, in bytes, or 0 if no IV is
+ * used.
+ *
+ * @param cipher_kt     Static cipher parameters
+ *
+ * @return              Size of the IV, in bytes, or 0 if the cipher does not
+ *                      use an IV.
+ */
+int cipher_kt_iv_size(const cipher_kt_t *cipher_kt);
+
+/**
+ * Returns the block size of the cipher, in bytes.
+ *
+ * @param cipher_kt     Static cipher parameters
+ *
+ * @return              Block size, in bytes.
+ */
+int cipher_kt_block_size(const cipher_kt_t *cipher_kt);
+
+/**
+ * Returns the MAC tag size of the cipher, in bytes.
+ *
+ * @param ctx           Static cipher parameters.
+ *
+ * @return              Tag size in bytes, or 0 if the tag size could not be
+ *                      determined.
+ */
+int cipher_kt_tag_size(const cipher_kt_t *cipher_kt);
+
+/**
+ * Returns the mode that the cipher runs in.
+ *
+ * @param cipher_kt     Static cipher parameters. May not be NULL.
+ *
+ * @return              Cipher mode, either \c OPENVPN_MODE_CBC, \c
+ *                      OPENVPN_MODE_OFB or \c OPENVPN_MODE_CFB
+ */
+int cipher_kt_mode(const cipher_kt_t *cipher_kt);
+
+/**
+ * Check if the supplied cipher is a supported CBC mode cipher.
+ *
+ * @param cipher        Static cipher parameters.
+ *
+ * @return              true iff the cipher is a CBC mode cipher.
+ */
+bool cipher_kt_mode_cbc(const cipher_kt_t *cipher);
+
+/**
+ * Check if the supplied cipher is a supported OFB or CFB mode cipher.
+ *
+ * @param cipher        Static cipher parameters.
+ *
+ * @return              true iff the cipher is a OFB or CFB mode cipher.
+ */
+bool cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher);
+
+/**
+ * Check if the supplied cipher is a supported AEAD mode cipher.
+ *
+ * @param cipher        Static cipher parameters.
+ *
+ * @return              true iff the cipher is a AEAD mode cipher.
+ */
+bool cipher_kt_mode_aead(const cipher_kt_t *cipher);
+
+
+/**
+ *
+ * Generic cipher functions
+ *
+ */
+
+/**
+ * Allocate a new cipher context
+ *
+ * @return              a new cipher context
+ */
+cipher_ctx_t *cipher_ctx_new(void);
+
+/**
+ * Cleanup and free a cipher context
+ *
+ * @param ctx           Cipher context.
+ */
+void cipher_ctx_free(cipher_ctx_t *ctx);
+
+/**
+ * Initialise a cipher context, based on the given key and key type.
+ *
+ * @param ctx           Cipher context. May not be NULL
+ * @param key           Buffer containing the key to use
+ * @param key_len       Length of the key, in bytes
+ * @param kt            Static cipher parameters to use
+ * @param enc           Whether to encrypt or decrypt (either
+ *                      \c MBEDTLS_OP_ENCRYPT or \c MBEDTLS_OP_DECRYPT).
+ */
+void cipher_ctx_init(cipher_ctx_t *ctx, const uint8_t *key, int key_len,
+                     const cipher_kt_t *kt, int enc);
+
+/**
+ * Returns the size of the IV used by the cipher, in bytes, or 0 if no IV is
+ * used.
+ *
+ * @param ctx           The cipher's context
+ *
+ * @return              Size of the IV, in bytes, or \c 0 if the cipher does not
+ *                      use an IV or ctx was NULL.
+ */
+int cipher_ctx_iv_length(const cipher_ctx_t *ctx);
+
+/**
+ * Gets the computed message authenticated code (MAC) tag for this cipher.
+ *
+ * @param ctx           The cipher's context
+ * @param tag           The buffer to write computed tag in.
+ * @param tag_size      The tag buffer size, in bytes.
+ */
+int cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len);
+
+/**
+ * Returns the block size of the cipher, in bytes.
+ *
+ * @param ctx           The cipher's context
+ *
+ * @return              Block size, in bytes, or 0 if ctx was NULL.
+ */
+int cipher_ctx_block_size(const cipher_ctx_t *ctx);
+
+/**
+ * Returns the mode that the cipher runs in.
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ *
+ * @return              Cipher mode, either \c OPENVPN_MODE_CBC, \c
+ *                      OPENVPN_MODE_OFB or \c OPENVPN_MODE_CFB
+ */
+int cipher_ctx_mode(const cipher_ctx_t *ctx);
+
+/**
+ * Returns the static cipher parameters for this context.
+ *
+ * @param ctx           Cipher's context.
+ *
+ * @return              Static cipher parameters for the supplied context, or
+ *                      NULL if unable to determine cipher parameters.
+ */
+const cipher_kt_t *cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx);
+
+/**
+ * Resets the given cipher context, setting the IV to the specified value.
+ * Preserves the associated key information.
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ * @param iv_buf        The IV to use.
+ *
+ * @return              \c 0 on failure, \c 1 on success.
+ */
+int cipher_ctx_reset(cipher_ctx_t *ctx, uint8_t *iv_buf);
+
+/**
+ * Updates the given cipher context, providing additional data (AD) for
+ * authenticated encryption with additional data (AEAD) cipher modes.
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ * @param src           Source buffer
+ * @param src_len       Length of the source buffer, in bytes
+ *
+ * @return              \c 0 on failure, \c 1 on success.
+ */
+int cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len);
+
+/**
+ * Updates the given cipher context, encrypting data in the source buffer, and
+ * placing any complete blocks in the destination buffer.
+ *
+ * Note that if a complete block cannot be written, data is cached in the
+ * context, and emitted at a later call to \c cipher_ctx_update, or by a call
+ * to \c cipher_ctx_final(). This implies that dst should have enough room for
+ * src_len + \c cipher_ctx_block_size().
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ * @param dst           Destination buffer
+ * @param dst_len       Length of the destination buffer, in bytes
+ * @param src           Source buffer
+ * @param src_len       Length of the source buffer, in bytes
+ *
+ * @return              \c 0 on failure, \c 1 on success.
+ */
+int cipher_ctx_update(cipher_ctx_t *ctx, uint8_t *dst, int *dst_len,
+                      uint8_t *src, int src_len);
+
+/**
+ * Pads the final cipher block using PKCS padding, and output to the destination
+ * buffer.
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ * @param dst           Destination buffer
+ * @param dst_len       Length of the destination buffer, in bytes
+ *
+ * @return              \c 0 on failure, \c 1 on success.
+ */
+int cipher_ctx_final(cipher_ctx_t *ctx, uint8_t *dst, int *dst_len);
+
+/**
+ * Like \c cipher_ctx_final, but check the computed authentication tag against
+ * the supplied (expected) tag. This function reports failure when the tags
+ * don't match.
+ *
+ * @param ctx           Cipher's context. May not be NULL.
+ * @param dst           Destination buffer.
+ * @param dst_len       Length of the destination buffer, in bytes.
+ * @param tag           The expected authentication tag.
+ * @param tag_len       The length of tag, in bytes.
+ *
+ * @return              \c 0 on failure, \c 1 on success.
+ */
+int cipher_ctx_final_check_tag(cipher_ctx_t *ctx, uint8_t *dst, int *dst_len,
+                               uint8_t *tag, size_t tag_len);
+
+
+/*
+ *
+ * Generic message digest information functions
+ *
+ */
+
+/*
+ * Max size in bytes of any HMAC key that might conceivably be used.
+ *
+ * This value is checked at compile time in crypto.c to make sure
+ * it is always at least EVP_MAX_MD_SIZE.  We define our own value
+ * for the same reason as above.
+ */
+#define MAX_HMAC_KEY_LENGTH 64
+
+/**
+ * Return message digest parameters, based on the given digest name. The
+ * contents of these parameters are library-specific, and can be used to
+ * initialise HMAC or message digest operations.
+ *
+ * @param digest        Name of the digest to retrieve parameters for (e.g.
+ *                      \c MD5).
+ *
+ * @return              A statically allocated structure containing parameters
+ *                      for the given message digest.
+ */
+const md_kt_t *md_kt_get(const char *digest);
+
+/**
+ * Retrieve a string describing the digest digest (e.g. \c SHA1).
+ *
+ * @param kt            Static message digest parameters
+ *
+ * @return              Statically allocated string describing the message
+ *                      digest.
+ */
+const char *md_kt_name(const md_kt_t *kt);
+
+/**
+ * Returns the size of the message digest, in bytes.
+ *
+ * @param kt            Static message digest parameters
+ *
+ * @return              Message digest size, in bytes, or 0 if ctx was NULL.
+ */
+int md_kt_size(const md_kt_t *kt);
+
+
+/*
+ *
+ * Generic message digest functions
+ *
+ */
+
+/*
+ * Calculates the message digest for the given buffer.
+ *
+ * @param kt            Static message digest parameters
+ * @param src           Buffer to digest. May not be NULL.
+ * @param src_len       The length of the incoming buffer.
+ * @param dst           Buffer to write the message digest to. May not be NULL.
+ *
+ * @return              \c 1 on success, \c 0 on failure
+ */
+int md_full(const md_kt_t *kt, const uint8_t *src, int src_len, uint8_t *dst);
+
+/*
+ * Allocate a new message digest context
+ *
+ * @return              a new zeroed MD context
+ */
+md_ctx_t *md_ctx_new(void);
+
+/*
+ * Free an existing, non-null message digest context
+ *
+ * @param ctx           Message digest context
+ */
+void md_ctx_free(md_ctx_t *ctx);
+
+/*
+ * Initialises the given message digest context.
+ *
+ * @param ctx           Message digest context
+ * @param kt            Static message digest parameters
+ */
+void md_ctx_init(md_ctx_t *ctx, const md_kt_t *kt);
+
+/*
+ * Free the given message digest context.
+ *
+ * @param ctx           Message digest context
+ */
+void md_ctx_cleanup(md_ctx_t *ctx);
+
+/*
+ * Returns the size of the message digest output by the given context
+ *
+ * @param ctx           Message digest context.
+ *
+ * @return              Size of the message digest, or \0 if ctx is NULL.
+ */
+int md_ctx_size(const md_ctx_t *ctx);
+
+/*
+ * Process the given data for use in the message digest.
+ *
+ * @param ctx           Message digest context. May not be NULL.
+ * @param src           Buffer to digest. May not be NULL.
+ * @param src_len       The length of the incoming buffer.
+ */
+void md_ctx_update(md_ctx_t *ctx, const uint8_t *src, int src_len);
+
+/*
+ * Output the message digest to the given buffer.
+ *
+ * @param ctx           Message digest context. May not be NULL.
+ * @param dst           Buffer to write the message digest to. May not be NULL.
+ */
+void md_ctx_final(md_ctx_t *ctx, uint8_t *dst);
+
+
+/*
+ *
+ * Generic HMAC functions
+ *
+ */
+
+/*
+ * Create a new HMAC context
+ *
+ * @return              A new HMAC context
+ */
+hmac_ctx_t *hmac_ctx_new(void);
+
+/*
+ * Free an existing HMAC context
+ *
+ * @param  ctx           HMAC context to free
+ */
+void hmac_ctx_free(hmac_ctx_t *ctx);
+
+/*
+ * Initialises the given HMAC context, using the given digest
+ * and key.
+ *
+ * @param ctx           HMAC context to intialise
+ * @param key           The key to use for the HMAC
+ * @param key_len       The key length to use
+ * @param kt            Static message digest parameters
+ *
+ */
+void hmac_ctx_init(hmac_ctx_t *ctx, const uint8_t *key, int key_length,
+                   const md_kt_t *kt);
+
+/*
+ * Free the given HMAC context.
+ *
+ * @param ctx           HMAC context
+ */
+void hmac_ctx_cleanup(hmac_ctx_t *ctx);
+
+/*
+ * Returns the size of the HMAC output by the given HMAC Context
+ *
+ * @param ctx           HMAC context.
+ *
+ * @return              Size of the HMAC, or \0 if ctx is NULL.
+ */
+int hmac_ctx_size(const hmac_ctx_t *ctx);
+
+/*
+ * Resets the given HMAC context, preserving the associated key information
+ *
+ * @param ctx           HMAC context. May not be NULL.
+ */
+void hmac_ctx_reset(hmac_ctx_t *ctx);
+
+/*
+ * Process the given data for use in the HMAC.
+ *
+ * @param ctx           HMAC context. May not be NULL.
+ * @param src           The buffer to HMAC. May not be NULL.
+ * @param src_len       The length of the incoming buffer.
+ */
+void hmac_ctx_update(hmac_ctx_t *ctx, const uint8_t *src, int src_len);
+
+/*
+ * Output the HMAC to the given buffer.
+ *
+ * @param ctx           HMAC context. May not be NULL.
+ * @param dst           buffer to write the HMAC to. May not be NULL.
+ */
+void hmac_ctx_final(hmac_ctx_t *ctx, uint8_t *dst);
+
+/**
+ * Translate an OpenVPN cipher name to a crypto library cipher name.
+ *
+ * @param cipher_name   An OpenVPN cipher name
+ *
+ * @return              The corresponding crypto library cipher name, or NULL
+ *                      if no matching cipher name was found.
+ */
+const char *translate_cipher_name_from_openvpn(const char *cipher_name);
+
+/**
+ * Translate a crypto library cipher name to an OpenVPN cipher name.
+ *
+ * @param cipher_name   A crypto library cipher name
+ *
+ * @return              The corresponding OpenVPN cipher name, or NULL if no
+ *                      matching cipher name was found.
+ */
+const char *translate_cipher_name_to_openvpn(const char *cipher_name);
+
+#endif /* CRYPTO_BACKEND_H_ */
diff --git a/src/openvpn/crypto_mbedtls.c b/src/openvpn/crypto_mbedtls.c
new file mode 100644
index 0000000..748043e
--- /dev/null
+++ b/src/openvpn/crypto_mbedtls.c
@@ -0,0 +1,902 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography mbed TLS-specific backend interface
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "errlevel.h"
+#include "basic.h"
+#include "buffer.h"
+#include "integer.h"
+#include "crypto_backend.h"
+#include "otime.h"
+#include "misc.h"
+
+#include <mbedtls/des.h>
+#include <mbedtls/error.h>
+#include <mbedtls/md5.h>
+#include <mbedtls/cipher.h>
+#include <mbedtls/havege.h>
+
+#include <mbedtls/entropy.h>
+
+
+/*
+ *
+ * Hardware engine support. Allows loading/unloading of engines.
+ *
+ */
+
+void
+crypto_init_lib_engine(const char *engine_name)
+{
+    msg(M_WARN, "Note: mbed TLS hardware crypto engine functionality is not "
+        "available");
+}
+
+/*
+ *
+ * Functions related to the core crypto library
+ *
+ */
+
+void
+crypto_init_lib(void)
+{
+}
+
+void
+crypto_uninit_lib(void)
+{
+}
+
+void
+crypto_clear_error(void)
+{
+}
+
+bool
+mbed_log_err(unsigned int flags, int errval, const char *prefix)
+{
+    if (0 != errval)
+    {
+        char errstr[256];
+        mbedtls_strerror(errval, errstr, sizeof(errstr));
+
+        if (NULL == prefix)
+        {
+            prefix = "mbed TLS error";
+        }
+        msg(flags, "%s: %s", prefix, errstr);
+    }
+
+    return 0 == errval;
+}
+
+bool
+mbed_log_func_line(unsigned int flags, int errval, const char *func,
+                   int line)
+{
+    char prefix[256];
+
+    if (!openvpn_snprintf(prefix, sizeof(prefix), "%s:%d", func, line))
+    {
+        return mbed_log_err(flags, errval, func);
+    }
+
+    return mbed_log_err(flags, errval, prefix);
+}
+
+
+#ifdef DMALLOC
+void
+crypto_init_dmalloc(void)
+{
+    msg(M_ERR, "Error: dmalloc support is not available for mbed TLS.");
+}
+#endif /* DMALLOC */
+
+const cipher_name_pair cipher_name_translation_table[] = {
+    { "BF-CBC", "BLOWFISH-CBC" },
+    { "BF-CFB", "BLOWFISH-CFB64" },
+    { "CAMELLIA-128-CFB", "CAMELLIA-128-CFB128" },
+    { "CAMELLIA-192-CFB", "CAMELLIA-192-CFB128" },
+    { "CAMELLIA-256-CFB", "CAMELLIA-256-CFB128" }
+};
+const size_t cipher_name_translation_table_count =
+    sizeof(cipher_name_translation_table) / sizeof(*cipher_name_translation_table);
+
+static void
+print_cipher(const cipher_kt_t *info)
+{
+    if (info && (cipher_kt_mode_cbc(info)
+#ifdef HAVE_AEAD_CIPHER_MODES
+                 || cipher_kt_mode_aead(info)
+#endif
+                 ))
+    {
+        const char *ssl_only = cipher_kt_mode_cbc(info) ?
+                               "" : ", TLS client/server mode only";
+        const char *var_key_size = info->flags & MBEDTLS_CIPHER_VARIABLE_KEY_LEN ?
+                                   " by default" : "";
+
+        printf("%s  (%d bit key%s, %d bit block%s)\n",
+               cipher_kt_name(info), cipher_kt_key_size(info) * 8, var_key_size,
+               cipher_kt_block_size(info) * 8, ssl_only);
+    }
+}
+
+void
+show_available_ciphers(void)
+{
+    const int *ciphers = mbedtls_cipher_list();
+
+#ifndef ENABLE_SMALL
+    printf("The following ciphers and cipher modes are available for use\n"
+           "with " PACKAGE_NAME ".  Each cipher shown below may be used as a\n"
+           "parameter to the --cipher option.  Using a CBC or GCM mode is\n"
+           "recommended.  In static key mode only CBC mode is allowed.\n\n");
+#endif
+
+    while (*ciphers != 0)
+    {
+        const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers);
+        if (info && cipher_kt_block_size(info) >= 128/8)
+        {
+            print_cipher(info);
+        }
+        ciphers++;
+    }
+
+    printf("\nThe following ciphers have a block size of less than 128 bits, \n"
+           "and are therefore deprecated.  Do not use unless you have to.\n\n");
+    ciphers = mbedtls_cipher_list();
+    while (*ciphers != 0)
+    {
+        const cipher_kt_t *info = mbedtls_cipher_info_from_type(*ciphers);
+        if (info && cipher_kt_block_size(info) < 128/8)
+        {
+            print_cipher(info);
+        }
+        ciphers++;
+    }
+    printf("\n");
+}
+
+void
+show_available_digests(void)
+{
+    const int *digests = mbedtls_md_list();
+
+#ifndef ENABLE_SMALL
+    printf("The following message digests are available for use with\n"
+           PACKAGE_NAME ".  A message digest is used in conjunction with\n"
+           "the HMAC function, to authenticate received packets.\n"
+           "You can specify a message digest as parameter to\n"
+           "the --auth option.\n\n");
+#endif
+
+    while (*digests != 0)
+    {
+        const mbedtls_md_info_t *info = mbedtls_md_info_from_type(*digests);
+
+        if (info)
+        {
+            printf("%s %d bit default key\n", mbedtls_md_get_name(info),
+                   mbedtls_md_get_size(info) * 8);
+        }
+        digests++;
+    }
+    printf("\n");
+}
+
+void
+show_available_engines(void)
+{
+    printf("Sorry, mbed TLS hardware crypto engine functionality is not "
+           "available\n");
+}
+
+/*
+ *
+ * Random number functions, used in cases where we want
+ * reasonably strong cryptographic random number generation
+ * without depleting our entropy pool.  Used for random
+ * IV values and a number of other miscellaneous tasks.
+ *
+ */
+
+/*
+ * Initialise the given ctr_drbg context, using a personalisation string and an
+ * entropy gathering function.
+ */
+mbedtls_ctr_drbg_context *
+rand_ctx_get(void)
+{
+    static mbedtls_entropy_context ec = {0};
+    static mbedtls_ctr_drbg_context cd_ctx = {0};
+    static bool rand_initialised = false;
+
+    if (!rand_initialised)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer pers_string = alloc_buf_gc(100, &gc);
+
+        /*
+         * Personalisation string, should be as unique as possible (see NIST
+         * 800-90 section 8.7.1). We have very little information at this stage.
+         * Include Program Name, memory address of the context and PID.
+         */
+        buf_printf(&pers_string, "OpenVPN %0u %p %s", platform_getpid(), &cd_ctx, time_string(0, 0, 0, &gc));
+
+        /* Initialise mbed TLS RNG, and built-in entropy sources */
+        mbedtls_entropy_init(&ec);
+
+        mbedtls_ctr_drbg_init(&cd_ctx);
+        if (!mbed_ok(mbedtls_ctr_drbg_seed(&cd_ctx, mbedtls_entropy_func, &ec,
+                                           BPTR(&pers_string), BLEN(&pers_string))))
+        {
+            msg(M_FATAL, "Failed to initialize random generator");
+        }
+
+        gc_free(&gc);
+        rand_initialised = true;
+    }
+
+    return &cd_ctx;
+}
+
+#ifdef ENABLE_PREDICTION_RESISTANCE
+void
+rand_ctx_enable_prediction_resistance(void)
+{
+    mbedtls_ctr_drbg_context *cd_ctx = rand_ctx_get();
+
+    mbedtls_ctr_drbg_set_prediction_resistance(cd_ctx, 1);
+}
+#endif /* ENABLE_PREDICTION_RESISTANCE */
+
+int
+rand_bytes(uint8_t *output, int len)
+{
+    mbedtls_ctr_drbg_context *rng_ctx = rand_ctx_get();
+
+    while (len > 0)
+    {
+        const size_t blen = min_int(len, MBEDTLS_CTR_DRBG_MAX_REQUEST);
+        if (0 != mbedtls_ctr_drbg_random(rng_ctx, output, blen))
+        {
+            return 0;
+        }
+
+        output += blen;
+        len -= blen;
+    }
+
+    return 1;
+}
+
+/*
+ *
+ * Key functions, allow manipulation of keys.
+ *
+ */
+
+
+int
+key_des_num_cblocks(const mbedtls_cipher_info_t *kt)
+{
+    int ret = 0;
+    if (kt->type == MBEDTLS_CIPHER_DES_CBC)
+    {
+        ret = 1;
+    }
+    if (kt->type == MBEDTLS_CIPHER_DES_EDE_CBC)
+    {
+        ret = 2;
+    }
+    if (kt->type == MBEDTLS_CIPHER_DES_EDE3_CBC)
+    {
+        ret = 3;
+    }
+
+    dmsg(D_CRYPTO_DEBUG, "CRYPTO INFO: n_DES_cblocks=%d", ret);
+    return ret;
+}
+
+bool
+key_des_check(uint8_t *key, int key_len, int ndc)
+{
+    int i;
+    struct buffer b;
+
+    buf_set_read(&b, key, key_len);
+
+    for (i = 0; i < ndc; ++i)
+    {
+        unsigned char *key = buf_read_alloc(&b, MBEDTLS_DES_KEY_SIZE);
+        if (!key)
+        {
+            msg(D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: insufficient key material");
+            goto err;
+        }
+        if (0 != mbedtls_des_key_check_weak(key))
+        {
+            msg(D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: weak key detected");
+            goto err;
+        }
+        if (0 != mbedtls_des_key_check_key_parity(key))
+        {
+            msg(D_CRYPT_ERRORS, "CRYPTO INFO: check_key_DES: bad parity detected");
+            goto err;
+        }
+    }
+    return true;
+
+err:
+    return false;
+}
+
+void
+key_des_fixup(uint8_t *key, int key_len, int ndc)
+{
+    int i;
+    struct buffer b;
+
+    buf_set_read(&b, key, key_len);
+    for (i = 0; i < ndc; ++i)
+    {
+        unsigned char *key = buf_read_alloc(&b, MBEDTLS_DES_KEY_SIZE);
+        if (!key)
+        {
+            msg(D_CRYPT_ERRORS, "CRYPTO INFO: fixup_key_DES: insufficient key material");
+            return;
+        }
+        mbedtls_des_key_set_parity(key);
+    }
+}
+
+/*
+ *
+ * Generic cipher key type functions
+ *
+ */
+
+
+const mbedtls_cipher_info_t *
+cipher_kt_get(const char *ciphername)
+{
+    const mbedtls_cipher_info_t *cipher = NULL;
+
+    ASSERT(ciphername);
+
+    cipher = mbedtls_cipher_info_from_string(ciphername);
+
+    if (NULL == cipher)
+    {
+        msg(D_LOW, "Cipher algorithm '%s' not found", ciphername);
+        return NULL;
+    }
+
+    if (cipher->key_bitlen/8 > MAX_CIPHER_KEY_LENGTH)
+    {
+        msg(D_LOW, "Cipher algorithm '%s' uses a default key size (%d bytes) "
+            "which is larger than " PACKAGE_NAME "'s current maximum key size "
+            "(%d bytes)", ciphername, cipher->key_bitlen/8, MAX_CIPHER_KEY_LENGTH);
+        return NULL;
+    }
+
+    return cipher;
+}
+
+const char *
+cipher_kt_name(const mbedtls_cipher_info_t *cipher_kt)
+{
+    if (NULL == cipher_kt)
+    {
+        return "[null-cipher]";
+    }
+
+    return translate_cipher_name_to_openvpn(cipher_kt->name);
+}
+
+int
+cipher_kt_key_size(const mbedtls_cipher_info_t *cipher_kt)
+{
+    if (NULL == cipher_kt)
+    {
+        return 0;
+    }
+
+    return cipher_kt->key_bitlen/8;
+}
+
+int
+cipher_kt_iv_size(const mbedtls_cipher_info_t *cipher_kt)
+{
+    if (NULL == cipher_kt)
+    {
+        return 0;
+    }
+    return cipher_kt->iv_size;
+}
+
+int
+cipher_kt_block_size(const mbedtls_cipher_info_t *cipher_kt)
+{
+    if (NULL == cipher_kt)
+    {
+        return 0;
+    }
+    return cipher_kt->block_size;
+}
+
+int
+cipher_kt_tag_size(const mbedtls_cipher_info_t *cipher_kt)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    if (cipher_kt && cipher_kt_mode_aead(cipher_kt))
+    {
+        return OPENVPN_AEAD_TAG_LENGTH;
+    }
+#endif
+    return 0;
+}
+
+int
+cipher_kt_mode(const mbedtls_cipher_info_t *cipher_kt)
+{
+    ASSERT(NULL != cipher_kt);
+    return cipher_kt->mode;
+}
+
+bool
+cipher_kt_mode_cbc(const cipher_kt_t *cipher)
+{
+    return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_CBC;
+}
+
+bool
+cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher)
+{
+    return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_OFB
+                      || cipher_kt_mode(cipher) == OPENVPN_MODE_CFB);
+}
+
+bool
+cipher_kt_mode_aead(const cipher_kt_t *cipher)
+{
+    return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_GCM;
+}
+
+
+/*
+ *
+ * Generic cipher context functions
+ *
+ */
+
+mbedtls_cipher_context_t *
+cipher_ctx_new(void)
+{
+    mbedtls_cipher_context_t *ctx;
+    ALLOC_OBJ(ctx, mbedtls_cipher_context_t);
+    return ctx;
+}
+
+void
+cipher_ctx_free(mbedtls_cipher_context_t *ctx)
+{
+    mbedtls_cipher_free(ctx);
+    free(ctx);
+}
+
+void
+cipher_ctx_init(mbedtls_cipher_context_t *ctx, const uint8_t *key, int key_len,
+                const mbedtls_cipher_info_t *kt, const mbedtls_operation_t operation)
+{
+    ASSERT(NULL != kt && NULL != ctx);
+
+    CLEAR(*ctx);
+
+    if (!mbed_ok(mbedtls_cipher_setup(ctx, kt)))
+    {
+        msg(M_FATAL, "mbed TLS cipher context init #1");
+    }
+
+    if (!mbed_ok(mbedtls_cipher_setkey(ctx, key, key_len*8, operation)))
+    {
+        msg(M_FATAL, "mbed TLS cipher set key");
+    }
+
+    /* make sure we used a big enough key */
+    ASSERT(ctx->key_bitlen <= key_len*8);
+}
+
+int
+cipher_ctx_iv_length(const mbedtls_cipher_context_t *ctx)
+{
+    return mbedtls_cipher_get_iv_size(ctx);
+}
+
+int
+cipher_ctx_get_tag(cipher_ctx_t *ctx, uint8_t *tag, int tag_len)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    if (tag_len > SIZE_MAX)
+    {
+        return 0;
+    }
+
+    if (!mbed_ok(mbedtls_cipher_write_tag(ctx, (unsigned char *) tag, tag_len)))
+    {
+        return 0;
+    }
+
+    return 1;
+#else  /* ifdef HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif /* HAVE_AEAD_CIPHER_MODES */
+}
+
+int
+cipher_ctx_block_size(const mbedtls_cipher_context_t *ctx)
+{
+    return mbedtls_cipher_get_block_size(ctx);
+}
+
+int
+cipher_ctx_mode(const mbedtls_cipher_context_t *ctx)
+{
+    ASSERT(NULL != ctx);
+
+    return cipher_kt_mode(ctx->cipher_info);
+}
+
+const cipher_kt_t *
+cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx)
+{
+    return ctx ? ctx->cipher_info : NULL;
+}
+
+int
+cipher_ctx_reset(mbedtls_cipher_context_t *ctx, uint8_t *iv_buf)
+{
+    if (!mbed_ok(mbedtls_cipher_reset(ctx)))
+    {
+        return 0;
+    }
+
+    if (!mbed_ok(mbedtls_cipher_set_iv(ctx, iv_buf, ctx->cipher_info->iv_size)))
+    {
+        return 0;
+    }
+
+    return 1;
+}
+
+int
+cipher_ctx_update_ad(cipher_ctx_t *ctx, const uint8_t *src, int src_len)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    if (src_len > SIZE_MAX)
+    {
+        return 0;
+    }
+
+    if (!mbed_ok(mbedtls_cipher_update_ad(ctx, src, src_len)))
+    {
+        return 0;
+    }
+
+    return 1;
+#else  /* ifdef HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif /* HAVE_AEAD_CIPHER_MODES */
+}
+
+int
+cipher_ctx_update(mbedtls_cipher_context_t *ctx, uint8_t *dst,
+                  int *dst_len, uint8_t *src, int src_len)
+{
+    size_t s_dst_len = *dst_len;
+
+    if (!mbed_ok(mbedtls_cipher_update(ctx, src, (size_t) src_len, dst,
+                                       &s_dst_len)))
+    {
+        return 0;
+    }
+
+    *dst_len = s_dst_len;
+
+    return 1;
+}
+
+int
+cipher_ctx_final(mbedtls_cipher_context_t *ctx, uint8_t *dst, int *dst_len)
+{
+    size_t s_dst_len = *dst_len;
+
+    if (!mbed_ok(mbedtls_cipher_finish(ctx, dst, &s_dst_len)))
+    {
+        return 0;
+    }
+
+    *dst_len = s_dst_len;
+
+    return 1;
+}
+
+int
+cipher_ctx_final_check_tag(mbedtls_cipher_context_t *ctx, uint8_t *dst,
+                           int *dst_len, uint8_t *tag, size_t tag_len)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    size_t olen = 0;
+
+    if (MBEDTLS_DECRYPT != ctx->operation)
+    {
+        return 0;
+    }
+
+    if (tag_len > SIZE_MAX)
+    {
+        return 0;
+    }
+
+    if (!mbed_ok(mbedtls_cipher_finish(ctx, dst, &olen)))
+    {
+        msg(D_CRYPT_ERRORS, "%s: cipher_ctx_final() failed", __func__);
+        return 0;
+    }
+
+    if (olen > INT_MAX)
+    {
+        return 0;
+    }
+    *dst_len = olen;
+
+    if (!mbed_ok(mbedtls_cipher_check_tag(ctx, (const unsigned char *) tag,
+                                          tag_len)))
+    {
+        return 0;
+    }
+
+    return 1;
+#else  /* ifdef HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif /* HAVE_AEAD_CIPHER_MODES */
+}
+
+void
+cipher_des_encrypt_ecb(const unsigned char key[DES_KEY_LENGTH],
+                       unsigned char *src,
+                       unsigned char *dst)
+{
+    mbedtls_des_context ctx;
+
+    ASSERT(mbed_ok(mbedtls_des_setkey_enc(&ctx, key)));
+    ASSERT(mbed_ok(mbedtls_des_crypt_ecb(&ctx, src, dst)));
+}
+
+
+
+/*
+ *
+ * Generic message digest information functions
+ *
+ */
+
+
+const mbedtls_md_info_t *
+md_kt_get(const char *digest)
+{
+    const mbedtls_md_info_t *md = NULL;
+    ASSERT(digest);
+
+    md = mbedtls_md_info_from_string(digest);
+    if (!md)
+    {
+        msg(M_FATAL, "Message hash algorithm '%s' not found", digest);
+    }
+    if (mbedtls_md_get_size(md) > MAX_HMAC_KEY_LENGTH)
+    {
+        msg(M_FATAL, "Message hash algorithm '%s' uses a default hash size (%d bytes) which is larger than " PACKAGE_NAME "'s current maximum hash size (%d bytes)",
+            digest,
+            mbedtls_md_get_size(md),
+            MAX_HMAC_KEY_LENGTH);
+    }
+    return md;
+}
+
+const char *
+md_kt_name(const mbedtls_md_info_t *kt)
+{
+    if (NULL == kt)
+    {
+        return "[null-digest]";
+    }
+    return mbedtls_md_get_name(kt);
+}
+
+int
+md_kt_size(const mbedtls_md_info_t *kt)
+{
+    if (NULL == kt)
+    {
+        return 0;
+    }
+    return mbedtls_md_get_size(kt);
+}
+
+/*
+ *
+ * Generic message digest functions
+ *
+ */
+
+int
+md_full(const md_kt_t *kt, const uint8_t *src, int src_len, uint8_t *dst)
+{
+    return 0 == mbedtls_md(kt, src, src_len, dst);
+}
+
+mbedtls_md_context_t *
+md_ctx_new(void)
+{
+    mbedtls_md_context_t *ctx;
+    ALLOC_OBJ_CLEAR(ctx, mbedtls_md_context_t);
+    return ctx;
+}
+
+void md_ctx_free(mbedtls_md_context_t *ctx)
+{
+    free(ctx);
+}
+
+void
+md_ctx_init(mbedtls_md_context_t *ctx, const mbedtls_md_info_t *kt)
+{
+    ASSERT(NULL != ctx && NULL != kt);
+
+    mbedtls_md_init(ctx);
+    ASSERT(0 == mbedtls_md_setup(ctx, kt, 0));
+    ASSERT(0 == mbedtls_md_starts(ctx));
+}
+
+void
+md_ctx_cleanup(mbedtls_md_context_t *ctx)
+{
+    mbedtls_md_free(ctx);
+}
+
+int
+md_ctx_size(const mbedtls_md_context_t *ctx)
+{
+    if (NULL == ctx)
+    {
+        return 0;
+    }
+    return mbedtls_md_get_size(ctx->md_info);
+}
+
+void
+md_ctx_update(mbedtls_md_context_t *ctx, const uint8_t *src, int src_len)
+{
+    ASSERT(0 == mbedtls_md_update(ctx, src, src_len));
+}
+
+void
+md_ctx_final(mbedtls_md_context_t *ctx, uint8_t *dst)
+{
+    ASSERT(0 == mbedtls_md_finish(ctx, dst));
+    mbedtls_md_free(ctx);
+}
+
+
+/*
+ *
+ * Generic HMAC functions
+ *
+ */
+
+
+/*
+ * TODO: re-enable dmsg for crypto debug
+ */
+
+mbedtls_md_context_t *
+hmac_ctx_new(void)
+{
+    mbedtls_md_context_t *ctx;
+    ALLOC_OBJ(ctx, mbedtls_md_context_t);
+    return ctx;
+}
+
+void
+hmac_ctx_free(mbedtls_md_context_t *ctx)
+{
+    free(ctx);
+}
+
+void
+hmac_ctx_init(mbedtls_md_context_t *ctx, const uint8_t *key, int key_len,
+              const mbedtls_md_info_t *kt)
+{
+    ASSERT(NULL != kt && NULL != ctx);
+
+    mbedtls_md_init(ctx);
+    ASSERT(0 == mbedtls_md_setup(ctx, kt, 1));
+    ASSERT(0 == mbedtls_md_hmac_starts(ctx, key, key_len));
+
+    /* make sure we used a big enough key */
+    ASSERT(mbedtls_md_get_size(kt) <= key_len);
+}
+
+void
+hmac_ctx_cleanup(mbedtls_md_context_t *ctx)
+{
+    mbedtls_md_free(ctx);
+}
+
+int
+hmac_ctx_size(const mbedtls_md_context_t *ctx)
+{
+    if (NULL == ctx)
+    {
+        return 0;
+    }
+    return mbedtls_md_get_size(ctx->md_info);
+}
+
+void
+hmac_ctx_reset(mbedtls_md_context_t *ctx)
+{
+    ASSERT(0 == mbedtls_md_hmac_reset(ctx));
+}
+
+void
+hmac_ctx_update(mbedtls_md_context_t *ctx, const uint8_t *src, int src_len)
+{
+    ASSERT(0 == mbedtls_md_hmac_update(ctx, src, src_len));
+}
+
+void
+hmac_ctx_final(mbedtls_md_context_t *ctx, uint8_t *dst)
+{
+    ASSERT(0 == mbedtls_md_hmac_finish(ctx, dst));
+}
+
+#endif /* ENABLE_CRYPTO && ENABLE_CRYPTO_MBEDTLS */
diff --git a/src/openvpn/crypto_mbedtls.h b/src/openvpn/crypto_mbedtls.h
new file mode 100644
index 0000000..452b06e
--- /dev/null
+++ b/src/openvpn/crypto_mbedtls.h
@@ -0,0 +1,150 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography mbed TLS-specific backend interface
+ */
+
+#ifndef CRYPTO_MBEDTLS_H_
+#define CRYPTO_MBEDTLS_H_
+
+#include <mbedtls/cipher.h>
+#include <mbedtls/md.h>
+#include <mbedtls/ctr_drbg.h>
+
+/** Generic cipher key type %context. */
+typedef mbedtls_cipher_info_t cipher_kt_t;
+
+/** Generic message digest key type %context. */
+typedef mbedtls_md_info_t md_kt_t;
+
+/** Generic cipher %context. */
+typedef mbedtls_cipher_context_t cipher_ctx_t;
+
+/** Generic message digest %context. */
+typedef mbedtls_md_context_t md_ctx_t;
+
+/** Generic HMAC %context. */
+typedef mbedtls_md_context_t hmac_ctx_t;
+
+/** Maximum length of an IV */
+#define OPENVPN_MAX_IV_LENGTH   MBEDTLS_MAX_IV_LENGTH
+
+/** Cipher is in CBC mode */
+#define OPENVPN_MODE_CBC        MBEDTLS_MODE_CBC
+
+/** Cipher is in OFB mode */
+#define OPENVPN_MODE_OFB        MBEDTLS_MODE_OFB
+
+/** Cipher is in CFB mode */
+#define OPENVPN_MODE_CFB        MBEDTLS_MODE_CFB
+
+/** Cipher is in GCM mode */
+#define OPENVPN_MODE_GCM        MBEDTLS_MODE_GCM
+
+/** Cipher should encrypt */
+#define OPENVPN_OP_ENCRYPT      MBEDTLS_ENCRYPT
+
+/** Cipher should decrypt */
+#define OPENVPN_OP_DECRYPT      MBEDTLS_DECRYPT
+
+#define MD4_DIGEST_LENGTH       16
+#define MD5_DIGEST_LENGTH       16
+#define SHA_DIGEST_LENGTH       20
+#define SHA256_DIGEST_LENGTH    32
+#define DES_KEY_LENGTH 8
+
+/**
+ * Returns a singleton instance of the mbed TLS random number generator.
+ *
+ * For PolarSSL/mbed TLS 1.1+, this is the CTR_DRBG random number generator. If it
+ * hasn't been initialised yet, the RNG will be initialised using the default
+ * entropy sources. Aside from the default platform entropy sources, an
+ * additional entropy source, the HAVEGE random number generator will also be
+ * added. During initialisation, a personalisation string will be added based
+ * on the time, the PID, and a pointer to the random context.
+ */
+mbedtls_ctr_drbg_context *rand_ctx_get(void);
+
+#ifdef ENABLE_PREDICTION_RESISTANCE
+/**
+ * Enable prediction resistance on the random number generator.
+ */
+void rand_ctx_enable_prediction_resistance(void);
+
+#endif
+
+/**
+ * Log the supplied mbed TLS error, prefixed by supplied prefix.
+ *
+ * @param flags         Flags to indicate error type and priority.
+ * @param errval        mbed TLS error code to convert to error message.
+ * @param prefix        Prefix to mbed TLS error message.
+ *
+ * @returns true if no errors are detected, false otherwise.
+ */
+bool mbed_log_err(unsigned int flags, int errval, const char *prefix);
+
+/**
+ * Log the supplied mbed TLS error, prefixed by function name and line number.
+ *
+ * @param flags         Flags to indicate error type and priority.
+ * @param errval        mbed TLS error code to convert to error message.
+ * @param func          Function name where error was reported.
+ * @param line          Line number where error was reported.
+ *
+ * @returns true if no errors are detected, false otherwise.
+ */
+bool mbed_log_func_line(unsigned int flags, int errval, const char *func,
+                        int line);
+
+/** Wraps mbed_log_func_line() to prevent function calls for non-errors */
+static inline bool
+mbed_log_func_line_lite(unsigned int flags, int errval,
+                        const char *func, int line)
+{
+    if (errval)
+    {
+        return mbed_log_func_line(flags, errval, func, line);
+    }
+    return true;
+}
+
+/**
+ * Check errval and log on error.
+ *
+ * Convenience wrapper to put around mbed TLS library calls, e.g.
+ *   if (!mbed_ok (mbedtls_ssl_func())) return 0;
+ * or
+ *   ASSERT (mbed_ok (mbedtls_ssl_func()));
+ *
+ * @param errval        mbed TLS error code to convert to error message.
+ *
+ * @returns true if no errors are detected, false otherwise.
+ */
+#define mbed_ok(errval) \
+    mbed_log_func_line_lite(D_CRYPT_ERRORS, errval, __func__, __LINE__)
+
+
+#endif /* CRYPTO_MBEDTLS_H_ */
diff --git a/src/openvpn/crypto_openssl.c b/src/openvpn/crypto_openssl.c
new file mode 100644
index 0000000..3abcc99
--- /dev/null
+++ b/src/openvpn/crypto_openssl.c
@@ -0,0 +1,975 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography OpenSSL-specific backend interface
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL)
+
+#include "basic.h"
+#include "buffer.h"
+#include "integer.h"
+#include "crypto.h"
+#include "crypto_backend.h"
+#include "openssl_compat.h"
+
+#include <openssl/des.h>
+#include <openssl/err.h>
+#include <openssl/evp.h>
+#include <openssl/objects.h>
+#include <openssl/rand.h>
+#include <openssl/ssl.h>
+
+/*
+ * Check for key size creepage.
+ */
+
+#if MAX_CIPHER_KEY_LENGTH < EVP_MAX_KEY_LENGTH
+#warning Some OpenSSL EVP ciphers now support key lengths greater than MAX_CIPHER_KEY_LENGTH -- consider increasing MAX_CIPHER_KEY_LENGTH
+#endif
+
+#if MAX_HMAC_KEY_LENGTH < EVP_MAX_MD_SIZE
+#warning Some OpenSSL HMAC message digests now support key lengths greater than MAX_HMAC_KEY_LENGTH -- consider increasing MAX_HMAC_KEY_LENGTH
+#endif
+
+#if HAVE_OPENSSL_ENGINE
+#include <openssl/engine.h>
+
+static bool engine_initialized = false; /* GLOBAL */
+
+static ENGINE *engine_persist = NULL;   /* GLOBAL */
+
+/* Try to load an engine in a shareable library */
+static ENGINE *
+try_load_engine(const char *engine)
+{
+    ENGINE *e = ENGINE_by_id("dynamic");
+    if (e)
+    {
+        if (!ENGINE_ctrl_cmd_string(e, "SO_PATH", engine, 0)
+            || !ENGINE_ctrl_cmd_string(e, "LOAD", NULL, 0))
+        {
+            ENGINE_free(e);
+            e = NULL;
+        }
+    }
+    return e;
+}
+
+static ENGINE *
+setup_engine(const char *engine)
+{
+    ENGINE *e = NULL;
+
+    ENGINE_load_builtin_engines();
+
+    if (engine)
+    {
+        if (strcmp(engine, "auto") == 0)
+        {
+            msg(M_INFO, "Initializing OpenSSL auto engine support");
+            ENGINE_register_all_complete();
+            return NULL;
+        }
+        if ((e = ENGINE_by_id(engine)) == NULL
+            && (e = try_load_engine(engine)) == NULL)
+        {
+            crypto_msg(M_FATAL, "OpenSSL error: cannot load engine '%s'",
+                       engine);
+        }
+
+        if (!ENGINE_set_default(e, ENGINE_METHOD_ALL))
+        {
+            crypto_msg(M_FATAL,
+                       "OpenSSL error: ENGINE_set_default failed on engine '%s'",
+                       engine);
+        }
+
+        msg(M_INFO, "Initializing OpenSSL support for engine '%s'",
+            ENGINE_get_id(e));
+    }
+    return e;
+}
+
+#endif /* HAVE_OPENSSL_ENGINE */
+
+void
+crypto_init_lib_engine(const char *engine_name)
+{
+#if HAVE_OPENSSL_ENGINE
+    if (!engine_initialized)
+    {
+        ASSERT(engine_name);
+        ASSERT(!engine_persist);
+        engine_persist = setup_engine(engine_name);
+        engine_initialized = true;
+    }
+#else  /* if HAVE_OPENSSL_ENGINE */
+    msg(M_WARN, "Note: OpenSSL hardware crypto engine functionality is not available");
+#endif
+}
+
+/*
+ *
+ * Functions related to the core crypto library
+ *
+ */
+
+void
+crypto_init_lib(void)
+{
+    /*
+     * If you build the OpenSSL library and OpenVPN with
+     * CRYPTO_MDEBUG, you will get a listing of OpenSSL
+     * memory leaks on program termination.
+     */
+
+#ifdef CRYPTO_MDEBUG
+    CRYPTO_mem_ctrl(CRYPTO_MEM_CHECK_ON);
+#endif
+}
+
+void
+crypto_uninit_lib(void)
+{
+#ifdef CRYPTO_MDEBUG
+    FILE *fp = fopen("sdlog", "w");
+    ASSERT(fp);
+    CRYPTO_mem_leaks_fp(fp);
+    fclose(fp);
+#endif
+
+#if HAVE_OPENSSL_ENGINE
+    if (engine_initialized)
+    {
+        ENGINE_cleanup();
+        engine_persist = NULL;
+        engine_initialized = false;
+    }
+#endif
+}
+
+void
+crypto_clear_error(void)
+{
+    ERR_clear_error();
+}
+
+void
+crypto_print_openssl_errors(const unsigned int flags)
+{
+    size_t err = 0;
+
+    while ((err = ERR_get_error()))
+    {
+        /* Be more clear about frequently occurring "no shared cipher" error */
+        if (ERR_GET_REASON(err) == SSL_R_NO_SHARED_CIPHER)
+        {
+            msg(D_CRYPT_ERRORS, "TLS error: The server has no TLS ciphersuites "
+                "in common with the client. Your --tls-cipher setting might be "
+                "too restrictive.");
+        }
+        else if (ERR_GET_REASON(err) == SSL_R_UNSUPPORTED_PROTOCOL)
+        {
+            msg(D_CRYPT_ERRORS, "TLS error: Unsupported protocol. This typically "
+                 "indicates that client and server have no common TLS version enabled. "
+                 "This can be caused by mismatched tls-version-min and tls-version-max "
+                 "options on client and server. "
+                 "If your OpenVPN client is between v2.3.6 and v2.3.2 try adding "
+                 "tls-version-min 1.0 to the client configuration to use TLS 1.0+ "
+                 "instead of TLS 1.0 only");
+        }
+        msg(flags, "OpenSSL: %s", ERR_error_string(err, NULL));
+    }
+}
+
+
+/*
+ *
+ * OpenSSL memory debugging.  If dmalloc debugging is enabled, tell
+ * OpenSSL to use our private malloc/realloc/free functions so that
+ * we can dispatch them to dmalloc.
+ *
+ */
+
+#ifdef DMALLOC
+static void *
+crypto_malloc(size_t size, const char *file, int line)
+{
+    return dmalloc_malloc(file, line, size, DMALLOC_FUNC_MALLOC, 0, 0);
+}
+
+static void *
+crypto_realloc(void *ptr, size_t size, const char *file, int line)
+{
+    return dmalloc_realloc(file, line, ptr, size, DMALLOC_FUNC_REALLOC, 0);
+}
+
+static void
+crypto_free(void *ptr)
+{
+    dmalloc_free(__FILE__, __LINE__, ptr, DMALLOC_FUNC_FREE);
+}
+
+void
+crypto_init_dmalloc(void)
+{
+    CRYPTO_set_mem_ex_functions(crypto_malloc,
+                                crypto_realloc,
+                                crypto_free);
+}
+#endif /* DMALLOC */
+
+const cipher_name_pair cipher_name_translation_table[] = {
+    { "AES-128-GCM", "id-aes128-GCM" },
+    { "AES-192-GCM", "id-aes192-GCM" },
+    { "AES-256-GCM", "id-aes256-GCM" },
+};
+const size_t cipher_name_translation_table_count =
+    sizeof(cipher_name_translation_table) / sizeof(*cipher_name_translation_table);
+
+
+static int
+cipher_name_cmp(const void *a, const void *b)
+{
+    const EVP_CIPHER *const *cipher_a = a;
+    const EVP_CIPHER *const *cipher_b = b;
+
+    const char *cipher_name_a =
+        translate_cipher_name_to_openvpn(EVP_CIPHER_name(*cipher_a));
+    const char *cipher_name_b =
+        translate_cipher_name_to_openvpn(EVP_CIPHER_name(*cipher_b));
+
+    return strcmp(cipher_name_a, cipher_name_b);
+}
+
+static void
+print_cipher(const EVP_CIPHER *cipher)
+{
+    const char *var_key_size =
+        (EVP_CIPHER_flags(cipher) & EVP_CIPH_VARIABLE_LENGTH) ?
+        " by default" : "";
+    const char *ssl_only = cipher_kt_mode_cbc(cipher) ?
+                           "" : ", TLS client/server mode only";
+
+    printf("%s  (%d bit key%s, %d bit block%s)\n",
+           translate_cipher_name_to_openvpn(EVP_CIPHER_name(cipher)),
+           EVP_CIPHER_key_length(cipher) * 8, var_key_size,
+           cipher_kt_block_size(cipher) * 8, ssl_only);
+}
+
+void
+show_available_ciphers(void)
+{
+    int nid;
+    size_t i;
+
+    /* If we ever exceed this, we must be more selective */
+    const EVP_CIPHER *cipher_list[1000];
+    size_t num_ciphers = 0;
+#ifndef ENABLE_SMALL
+    printf("The following ciphers and cipher modes are available for use\n"
+           "with " PACKAGE_NAME ".  Each cipher shown below may be use as a\n"
+           "parameter to the --cipher option.  The default key size is\n"
+           "shown as well as whether or not it can be changed with the\n"
+           "--keysize directive.  Using a CBC or GCM mode is recommended.\n"
+           "In static key mode only CBC mode is allowed.\n\n");
+#endif
+
+    for (nid = 0; nid < 10000; ++nid)
+    {
+        const EVP_CIPHER *cipher = EVP_get_cipherbynid(nid);
+        if (cipher && (cipher_kt_mode_cbc(cipher)
+#ifdef ENABLE_OFB_CFB_MODE
+                       || cipher_kt_mode_ofb_cfb(cipher)
+#endif
+#ifdef HAVE_AEAD_CIPHER_MODES
+                       || cipher_kt_mode_aead(cipher)
+#endif
+                       ))
+        {
+            cipher_list[num_ciphers++] = cipher;
+        }
+        if (num_ciphers == (sizeof(cipher_list)/sizeof(*cipher_list)))
+        {
+            msg(M_WARN, "WARNING: Too many ciphers, not showing all");
+            break;
+        }
+    }
+
+    qsort(cipher_list, num_ciphers, sizeof(*cipher_list), cipher_name_cmp);
+
+    for (i = 0; i < num_ciphers; i++) {
+        if (cipher_kt_block_size(cipher_list[i]) >= 128/8)
+        {
+            print_cipher(cipher_list[i]);
+        }
+    }
+
+    printf("\nThe following ciphers have a block size of less than 128 bits, \n"
+           "and are therefore deprecated.  Do not use unless you have to.\n\n");
+    for (i = 0; i < num_ciphers; i++) {
+        if (cipher_kt_block_size(cipher_list[i]) < 128/8)
+        {
+            print_cipher(cipher_list[i]);
+        }
+    }
+    printf("\n");
+}
+
+void
+show_available_digests(void)
+{
+    int nid;
+
+#ifndef ENABLE_SMALL
+    printf("The following message digests are available for use with\n"
+           PACKAGE_NAME ".  A message digest is used in conjunction with\n"
+           "the HMAC function, to authenticate received packets.\n"
+           "You can specify a message digest as parameter to\n"
+           "the --auth option.\n\n");
+#endif
+
+    for (nid = 0; nid < 10000; ++nid)
+    {
+        const EVP_MD *digest = EVP_get_digestbynid(nid);
+        if (digest)
+        {
+            printf("%s %d bit digest size\n",
+                   OBJ_nid2sn(nid), EVP_MD_size(digest) * 8);
+        }
+    }
+    printf("\n");
+}
+
+void
+show_available_engines(void)
+{
+#if HAVE_OPENSSL_ENGINE /* Only defined for OpenSSL */
+    ENGINE *e;
+
+    printf("OpenSSL Crypto Engines\n\n");
+
+    ENGINE_load_builtin_engines();
+
+    e = ENGINE_get_first();
+    while (e)
+    {
+        printf("%s [%s]\n",
+               ENGINE_get_name(e),
+               ENGINE_get_id(e));
+        e = ENGINE_get_next(e);
+    }
+    ENGINE_cleanup();
+#else  /* if HAVE_OPENSSL_ENGINE */
+    printf("Sorry, OpenSSL hardware crypto engine functionality is not available.\n");
+#endif
+}
+
+/*
+ *
+ * Random number functions, used in cases where we want
+ * reasonably strong cryptographic random number generation
+ * without depleting our entropy pool.  Used for random
+ * IV values and a number of other miscellaneous tasks.
+ *
+ */
+
+int
+rand_bytes(uint8_t *output, int len)
+{
+    if (unlikely(1 != RAND_bytes(output, len)))
+    {
+        crypto_msg(D_CRYPT_ERRORS, "RAND_bytes() failed");
+        return 0;
+    }
+    return 1;
+}
+
+/*
+ *
+ * Key functions, allow manipulation of keys.
+ *
+ */
+
+
+int
+key_des_num_cblocks(const EVP_CIPHER *kt)
+{
+    int ret = 0;
+    const char *name = OBJ_nid2sn(EVP_CIPHER_nid(kt));
+    if (name)
+    {
+        if (!strncmp(name, "DES-", 4))
+        {
+            ret = EVP_CIPHER_key_length(kt) / sizeof(DES_cblock);
+        }
+        else if (!strncmp(name, "DESX-", 5))
+        {
+            ret = 1;
+        }
+    }
+    dmsg(D_CRYPTO_DEBUG, "CRYPTO INFO: n_DES_cblocks=%d", ret);
+    return ret;
+}
+
+bool
+key_des_check(uint8_t *key, int key_len, int ndc)
+{
+    int i;
+    struct buffer b;
+
+    buf_set_read(&b, key, key_len);
+
+    for (i = 0; i < ndc; ++i)
+    {
+        DES_cblock *dc = (DES_cblock *) buf_read_alloc(&b, sizeof(DES_cblock));
+        if (!dc)
+        {
+            crypto_msg(D_CRYPT_ERRORS,
+                       "CRYPTO INFO: check_key_DES: insufficient key material");
+            goto err;
+        }
+        if (DES_is_weak_key(dc))
+        {
+            crypto_msg(D_CRYPT_ERRORS,
+                       "CRYPTO INFO: check_key_DES: weak key detected");
+            goto err;
+        }
+        if (!DES_check_key_parity(dc))
+        {
+            crypto_msg(D_CRYPT_ERRORS,
+                       "CRYPTO INFO: check_key_DES: bad parity detected");
+            goto err;
+        }
+    }
+    return true;
+
+err:
+    ERR_clear_error();
+    return false;
+}
+
+void
+key_des_fixup(uint8_t *key, int key_len, int ndc)
+{
+    int i;
+    struct buffer b;
+
+    buf_set_read(&b, key, key_len);
+    for (i = 0; i < ndc; ++i)
+    {
+        DES_cblock *dc = (DES_cblock *) buf_read_alloc(&b, sizeof(DES_cblock));
+        if (!dc)
+        {
+            msg(D_CRYPT_ERRORS, "CRYPTO INFO: fixup_key_DES: insufficient key material");
+            ERR_clear_error();
+            return;
+        }
+        DES_set_odd_parity(dc);
+    }
+}
+
+
+/*
+ *
+ * Generic cipher key type functions
+ *
+ */
+
+
+const EVP_CIPHER *
+cipher_kt_get(const char *ciphername)
+{
+    const EVP_CIPHER *cipher = NULL;
+
+    ASSERT(ciphername);
+
+    cipher = EVP_get_cipherbyname(ciphername);
+
+    if (NULL == cipher)
+    {
+        crypto_msg(D_LOW, "Cipher algorithm '%s' not found", ciphername);
+        return NULL;
+    }
+
+
+    if (EVP_CIPHER_key_length(cipher) > MAX_CIPHER_KEY_LENGTH)
+    {
+        msg(D_LOW, "Cipher algorithm '%s' uses a default key size (%d bytes) "
+            "which is larger than " PACKAGE_NAME "'s current maximum key size "
+            "(%d bytes)", ciphername, EVP_CIPHER_key_length(cipher),
+            MAX_CIPHER_KEY_LENGTH);
+        return NULL;
+    }
+
+    return cipher;
+}
+
+const char *
+cipher_kt_name(const EVP_CIPHER *cipher_kt)
+{
+    if (NULL == cipher_kt)
+    {
+        return "[null-cipher]";
+    }
+    return EVP_CIPHER_name(cipher_kt);
+}
+
+int
+cipher_kt_key_size(const EVP_CIPHER *cipher_kt)
+{
+    return EVP_CIPHER_key_length(cipher_kt);
+}
+
+int
+cipher_kt_iv_size(const EVP_CIPHER *cipher_kt)
+{
+    return EVP_CIPHER_iv_length(cipher_kt);
+}
+
+int
+cipher_kt_block_size(const EVP_CIPHER *cipher)
+{
+    /*
+     * OpenSSL reports OFB/CFB/GCM cipher block sizes as '1 byte'.  To work
+     * around that, try to replace the mode with 'CBC' and return the block size
+     * reported for that cipher, if possible.  If that doesn't work, just return
+     * the value reported by OpenSSL.
+     */
+    char *name = NULL;
+    char *mode_str = NULL;
+    const char *orig_name = NULL;
+    const EVP_CIPHER *cbc_cipher = NULL;
+
+    int block_size = EVP_CIPHER_block_size(cipher);
+
+    orig_name = cipher_kt_name(cipher);
+    if (!orig_name)
+    {
+        goto cleanup;
+    }
+
+    name = string_alloc(translate_cipher_name_to_openvpn(orig_name), NULL);
+    mode_str = strrchr(name, '-');
+    if (!mode_str || strlen(mode_str) < 4)
+    {
+        goto cleanup;
+    }
+
+    strcpy(mode_str, "-CBC");
+
+    cbc_cipher = EVP_get_cipherbyname(translate_cipher_name_from_openvpn(name));
+    if (cbc_cipher)
+    {
+        block_size = EVP_CIPHER_block_size(cbc_cipher);
+    }
+
+cleanup:
+    free(name);
+    return block_size;
+}
+
+int
+cipher_kt_tag_size(const EVP_CIPHER *cipher_kt)
+{
+    if (cipher_kt_mode_aead(cipher_kt))
+    {
+        return OPENVPN_AEAD_TAG_LENGTH;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+int
+cipher_kt_mode(const EVP_CIPHER *cipher_kt)
+{
+    ASSERT(NULL != cipher_kt);
+    return EVP_CIPHER_mode(cipher_kt);
+}
+
+bool
+cipher_kt_mode_cbc(const cipher_kt_t *cipher)
+{
+    return cipher && cipher_kt_mode(cipher) == OPENVPN_MODE_CBC
+#ifdef EVP_CIPH_FLAG_AEAD_CIPHER
+           /* Exclude AEAD cipher modes, they require a different API */
+           && !(EVP_CIPHER_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER)
+#endif
+    ;
+}
+
+bool
+cipher_kt_mode_ofb_cfb(const cipher_kt_t *cipher)
+{
+    return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_OFB
+                      || cipher_kt_mode(cipher) == OPENVPN_MODE_CFB)
+#ifdef EVP_CIPH_FLAG_AEAD_CIPHER
+           /* Exclude AEAD cipher modes, they require a different API */
+           && !(EVP_CIPHER_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER)
+#endif
+    ;
+}
+
+bool
+cipher_kt_mode_aead(const cipher_kt_t *cipher)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    return cipher && (cipher_kt_mode(cipher) == OPENVPN_MODE_GCM);
+#else
+    return false;
+#endif
+}
+
+/*
+ *
+ * Generic cipher context functions
+ *
+ */
+
+cipher_ctx_t *
+cipher_ctx_new(void)
+{
+    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
+    check_malloc_return(ctx);
+    return ctx;
+}
+
+void
+cipher_ctx_free(EVP_CIPHER_CTX *ctx)
+{
+    EVP_CIPHER_CTX_free(ctx);
+}
+
+void
+cipher_ctx_init(EVP_CIPHER_CTX *ctx, const uint8_t *key, int key_len,
+                const EVP_CIPHER *kt, int enc)
+{
+    ASSERT(NULL != kt && NULL != ctx);
+
+    EVP_CIPHER_CTX_reset(ctx);
+    if (!EVP_CipherInit(ctx, kt, NULL, NULL, enc))
+    {
+        crypto_msg(M_FATAL, "EVP cipher init #1");
+    }
+#ifdef HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH
+    if (!EVP_CIPHER_CTX_set_key_length(ctx, key_len))
+    {
+        crypto_msg(M_FATAL, "EVP set key size");
+    }
+#endif
+    if (!EVP_CipherInit_ex(ctx, NULL, NULL, key, NULL, enc))
+    {
+        crypto_msg(M_FATAL, "EVP cipher init #2");
+    }
+
+    /* make sure we used a big enough key */
+    ASSERT(EVP_CIPHER_CTX_key_length(ctx) <= key_len);
+}
+
+int
+cipher_ctx_iv_length(const EVP_CIPHER_CTX *ctx)
+{
+    return EVP_CIPHER_CTX_iv_length(ctx);
+}
+
+int
+cipher_ctx_get_tag(EVP_CIPHER_CTX *ctx, uint8_t *tag_buf, int tag_size)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    return EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, tag_size, tag_buf);
+#else
+    ASSERT(0);
+#endif
+}
+
+int
+cipher_ctx_block_size(const EVP_CIPHER_CTX *ctx)
+{
+    return EVP_CIPHER_CTX_block_size(ctx);
+}
+
+int
+cipher_ctx_mode(const EVP_CIPHER_CTX *ctx)
+{
+    return EVP_CIPHER_CTX_mode(ctx);
+}
+
+const cipher_kt_t *
+cipher_ctx_get_cipher_kt(const cipher_ctx_t *ctx)
+{
+    return ctx ? EVP_CIPHER_CTX_cipher(ctx) : NULL;
+}
+
+
+int
+cipher_ctx_reset(EVP_CIPHER_CTX *ctx, uint8_t *iv_buf)
+{
+    return EVP_CipherInit_ex(ctx, NULL, NULL, NULL, iv_buf, -1);
+}
+
+int
+cipher_ctx_update_ad(EVP_CIPHER_CTX *ctx, const uint8_t *src, int src_len)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    int len;
+    if (!EVP_CipherUpdate(ctx, NULL, &len, src, src_len))
+    {
+        crypto_msg(M_FATAL, "%s: EVP_CipherUpdate() failed", __func__);
+    }
+    return 1;
+#else  /* ifdef HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif
+}
+
+int
+cipher_ctx_update(EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len,
+                  uint8_t *src, int src_len)
+{
+    if (!EVP_CipherUpdate(ctx, dst, dst_len, src, src_len))
+    {
+        crypto_msg(M_FATAL, "%s: EVP_CipherUpdate() failed", __func__);
+    }
+    return 1;
+}
+
+int
+cipher_ctx_final(EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len)
+{
+    return EVP_CipherFinal(ctx, dst, dst_len);
+}
+
+int
+cipher_ctx_final_check_tag(EVP_CIPHER_CTX *ctx, uint8_t *dst, int *dst_len,
+                           uint8_t *tag, size_t tag_len)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+    ASSERT(tag_len < SIZE_MAX);
+    if (!EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, tag_len, tag))
+    {
+        return 0;
+    }
+
+    return cipher_ctx_final(ctx, dst, dst_len);
+#else  /* ifdef HAVE_AEAD_CIPHER_MODES */
+    ASSERT(0);
+#endif
+}
+
+void
+cipher_des_encrypt_ecb(const unsigned char key[DES_KEY_LENGTH],
+                       unsigned char *src,
+                       unsigned char *dst)
+{
+    DES_key_schedule sched;
+
+    DES_set_key_unchecked((DES_cblock *)key, &sched);
+    DES_ecb_encrypt((DES_cblock *)src, (DES_cblock *)dst, &sched, DES_ENCRYPT);
+}
+
+/*
+ *
+ * Generic message digest information functions
+ *
+ */
+
+
+const EVP_MD *
+md_kt_get(const char *digest)
+{
+    const EVP_MD *md = NULL;
+    ASSERT(digest);
+    md = EVP_get_digestbyname(digest);
+    if (!md)
+    {
+        crypto_msg(M_FATAL, "Message hash algorithm '%s' not found", digest);
+    }
+    if (EVP_MD_size(md) > MAX_HMAC_KEY_LENGTH)
+    {
+        crypto_msg(M_FATAL, "Message hash algorithm '%s' uses a default hash "
+                   "size (%d bytes) which is larger than " PACKAGE_NAME "'s current "
+                   "maximum hash size (%d bytes)",
+                   digest, EVP_MD_size(md), MAX_HMAC_KEY_LENGTH);
+    }
+    return md;
+}
+
+const char *
+md_kt_name(const EVP_MD *kt)
+{
+    if (NULL == kt)
+    {
+        return "[null-digest]";
+    }
+    return EVP_MD_name(kt);
+}
+
+int
+md_kt_size(const EVP_MD *kt)
+{
+    return EVP_MD_size(kt);
+}
+
+
+/*
+ *
+ * Generic message digest functions
+ *
+ */
+
+int
+md_full(const EVP_MD *kt, const uint8_t *src, int src_len, uint8_t *dst)
+{
+    unsigned int in_md_len = 0;
+
+    return EVP_Digest(src, src_len, dst, &in_md_len, kt, NULL);
+}
+
+EVP_MD_CTX *
+md_ctx_new(void)
+{
+    EVP_MD_CTX *ctx = EVP_MD_CTX_new();
+    check_malloc_return(ctx);
+    return ctx;
+}
+
+void md_ctx_free(EVP_MD_CTX *ctx)
+{
+    EVP_MD_CTX_free(ctx);
+}
+
+void
+md_ctx_init(EVP_MD_CTX *ctx, const EVP_MD *kt)
+{
+    ASSERT(NULL != ctx && NULL != kt);
+
+    EVP_MD_CTX_init(ctx);
+    EVP_DigestInit(ctx, kt);
+}
+
+void
+md_ctx_cleanup(EVP_MD_CTX *ctx)
+{
+    EVP_MD_CTX_reset(ctx);
+}
+
+int
+md_ctx_size(const EVP_MD_CTX *ctx)
+{
+    return EVP_MD_CTX_size(ctx);
+}
+
+void
+md_ctx_update(EVP_MD_CTX *ctx, const uint8_t *src, int src_len)
+{
+    EVP_DigestUpdate(ctx, src, src_len);
+}
+
+void
+md_ctx_final(EVP_MD_CTX *ctx, uint8_t *dst)
+{
+    unsigned int in_md_len = 0;
+
+    EVP_DigestFinal(ctx, dst, &in_md_len);
+}
+
+
+/*
+ *
+ * Generic HMAC functions
+ *
+ */
+
+HMAC_CTX *
+hmac_ctx_new(void)
+{
+    HMAC_CTX *ctx = HMAC_CTX_new();
+    check_malloc_return(ctx);
+    return ctx;
+}
+
+void
+hmac_ctx_free(HMAC_CTX *ctx)
+{
+    HMAC_CTX_free(ctx);
+}
+
+void
+hmac_ctx_init(HMAC_CTX *ctx, const uint8_t *key, int key_len,
+              const EVP_MD *kt)
+{
+    ASSERT(NULL != kt && NULL != ctx);
+
+    HMAC_CTX_reset(ctx);
+    HMAC_Init_ex(ctx, key, key_len, kt, NULL);
+
+    /* make sure we used a big enough key */
+    ASSERT(HMAC_size(ctx) <= key_len);
+}
+
+void
+hmac_ctx_cleanup(HMAC_CTX *ctx)
+{
+    HMAC_CTX_reset(ctx);
+}
+
+int
+hmac_ctx_size(const HMAC_CTX *ctx)
+{
+    return HMAC_size(ctx);
+}
+
+void
+hmac_ctx_reset(HMAC_CTX *ctx)
+{
+    HMAC_Init_ex(ctx, NULL, 0, NULL, NULL);
+}
+
+void
+hmac_ctx_update(HMAC_CTX *ctx, const uint8_t *src, int src_len)
+{
+    HMAC_Update(ctx, src, src_len);
+}
+
+void
+hmac_ctx_final(HMAC_CTX *ctx, uint8_t *dst)
+{
+    unsigned int in_hmac_len = 0;
+
+    HMAC_Final(ctx, dst, &in_hmac_len);
+}
+
+#endif /* ENABLE_CRYPTO && ENABLE_CRYPTO_OPENSSL */
diff --git a/src/openvpn/crypto_openssl.h b/src/openvpn/crypto_openssl.h
new file mode 100644
index 0000000..0a41370
--- /dev/null
+++ b/src/openvpn/crypto_openssl.h
@@ -0,0 +1,105 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Cryptography OpenSSL-specific backend interface
+ */
+
+#ifndef CRYPTO_OPENSSL_H_
+#define CRYPTO_OPENSSL_H_
+
+#include <openssl/evp.h>
+#include <openssl/hmac.h>
+#include <openssl/md5.h>
+#include <openssl/sha.h>
+
+/** Generic cipher key type %context. */
+typedef EVP_CIPHER cipher_kt_t;
+
+/** Generic message digest key type %context. */
+typedef EVP_MD md_kt_t;
+
+/** Generic cipher %context. */
+typedef EVP_CIPHER_CTX cipher_ctx_t;
+
+/** Generic message digest %context. */
+typedef EVP_MD_CTX md_ctx_t;
+
+/** Generic HMAC %context. */
+typedef HMAC_CTX hmac_ctx_t;
+
+/** Maximum length of an IV */
+#define OPENVPN_MAX_IV_LENGTH   EVP_MAX_IV_LENGTH
+
+/** Cipher is in CBC mode */
+#define OPENVPN_MODE_CBC        EVP_CIPH_CBC_MODE
+
+/** Cipher is in OFB mode */
+#define OPENVPN_MODE_OFB        EVP_CIPH_OFB_MODE
+
+/** Cipher is in CFB mode */
+#define OPENVPN_MODE_CFB        EVP_CIPH_CFB_MODE
+
+#ifdef HAVE_AEAD_CIPHER_MODES
+
+/** Cipher is in GCM mode */
+#define OPENVPN_MODE_GCM        EVP_CIPH_GCM_MODE
+
+#endif /* HAVE_AEAD_CIPHER_MODES */
+
+/** Cipher should encrypt */
+#define OPENVPN_OP_ENCRYPT      1
+
+/** Cipher should decrypt */
+#define OPENVPN_OP_DECRYPT      0
+
+#define DES_KEY_LENGTH 8
+#define MD4_DIGEST_LENGTH       16
+
+/**
+ * Retrieve any occurred OpenSSL errors and print those errors.
+ *
+ * Note that this function uses the not thread-safe OpenSSL error API.
+ *
+ * @param flags         Flags to indicate error type and priority.
+ */
+void crypto_print_openssl_errors(const unsigned int flags);
+
+/**
+ * Retrieve any OpenSSL errors, then print the supplied error message.
+ *
+ * This is just a convenience wrapper for often occurring situations.
+ *
+ * @param flags         Flags to indicate error type and priority.
+ * @param format        Format string to print.
+ * @param format args   (optional) arguments for the format string.
+ */
+#define crypto_msg(flags, ...) \
+    do { \
+        crypto_print_openssl_errors(nonfatal(flags)); \
+        msg((flags), __VA_ARGS__); \
+    } while (false)
+
+
+#endif /* CRYPTO_OPENSSL_H_ */
diff --git a/src/openvpn/cryptoapi.c b/src/openvpn/cryptoapi.c
new file mode 100644
index 0000000..0f95d00
--- /dev/null
+++ b/src/openvpn/cryptoapi.c
@@ -0,0 +1,1033 @@
+/*
+ * Copyright (c) 2004 Peter 'Luna' Runestig <peter@runestig.com>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without modifi-
+ * cation, are permitted provided that the following conditions are met:
+ *
+ *   o  Redistributions of source code must retain the above copyright notice,
+ *      this list of conditions and the following disclaimer.
+ *
+ *   o  Redistributions in binary form must reproduce the above copyright no-
+ *      tice, this list of conditions and the following disclaimer in the do-
+ *      cumentation and/or other materials provided with the distribution.
+ *
+ *   o  The names of the contributors may not be used to endorse or promote
+ *      products derived from this software without specific prior written
+ *      permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LI-
+ * ABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUEN-
+ * TIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEV-
+ * ER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABI-
+ * LITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+ * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTOAPI
+
+#include <openssl/ssl.h>
+#include <openssl/evp.h>
+#include <openssl/err.h>
+#include <windows.h>
+#include <wincrypt.h>
+#include <ncrypt.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <assert.h>
+
+#include "buffer.h"
+#include "openssl_compat.h"
+#include "win32.h"
+
+/* MinGW w32api 3.17 is still incomplete when it comes to CryptoAPI while
+ * MinGW32-w64 defines all macros used. This is a hack around that problem.
+ */
+#ifndef CERT_SYSTEM_STORE_LOCATION_SHIFT
+#define CERT_SYSTEM_STORE_LOCATION_SHIFT 16
+#endif
+#ifndef CERT_SYSTEM_STORE_CURRENT_USER_ID
+#define CERT_SYSTEM_STORE_CURRENT_USER_ID 1
+#endif
+#ifndef CERT_SYSTEM_STORE_CURRENT_USER
+#define CERT_SYSTEM_STORE_CURRENT_USER (CERT_SYSTEM_STORE_CURRENT_USER_ID << CERT_SYSTEM_STORE_LOCATION_SHIFT)
+#endif
+#ifndef CERT_STORE_READONLY_FLAG
+#define CERT_STORE_READONLY_FLAG 0x00008000
+#endif
+#ifndef CERT_STORE_OPEN_EXISTING_FLAG
+#define CERT_STORE_OPEN_EXISTING_FLAG 0x00004000
+#endif
+
+/* Size of an SSL signature: MD5+SHA1 */
+#define SSL_SIG_LENGTH  36
+
+/* try to funnel any Windows/CryptoAPI error messages to OpenSSL ERR_... */
+#define ERR_LIB_CRYPTOAPI (ERR_LIB_USER + 69)   /* 69 is just a number... */
+#define CRYPTOAPIerr(f)   err_put_ms_error(GetLastError(), (f), __FILE__, __LINE__)
+#define CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE                  100
+#define CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE          101
+#define CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY   102
+#define CRYPTOAPI_F_CRYPT_CREATE_HASH                       103
+#define CRYPTOAPI_F_CRYPT_GET_HASH_PARAM                    104
+#define CRYPTOAPI_F_CRYPT_SET_HASH_PARAM                    105
+#define CRYPTOAPI_F_CRYPT_SIGN_HASH                         106
+#define CRYPTOAPI_F_LOAD_LIBRARY                            107
+#define CRYPTOAPI_F_GET_PROC_ADDRESS                        108
+#define CRYPTOAPI_F_NCRYPT_SIGN_HASH                        109
+
+static ERR_STRING_DATA CRYPTOAPI_str_functs[] = {
+    { ERR_PACK(ERR_LIB_CRYPTOAPI, 0, 0),                                    "microsoft cryptoapi"},
+    { ERR_PACK(0, CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE, 0),                   "CertOpenSystemStore" },
+    { ERR_PACK(0, CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE, 0),           "CertFindCertificateInStore" },
+    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY, 0),    "CryptAcquireCertificatePrivateKey" },
+    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_CREATE_HASH, 0),                        "CryptCreateHash" },
+    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_GET_HASH_PARAM, 0),                     "CryptGetHashParam" },
+    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_SET_HASH_PARAM, 0),                     "CryptSetHashParam" },
+    { ERR_PACK(0, CRYPTOAPI_F_CRYPT_SIGN_HASH, 0),                          "CryptSignHash" },
+    { ERR_PACK(0, CRYPTOAPI_F_LOAD_LIBRARY, 0),                             "LoadLibrary" },
+    { ERR_PACK(0, CRYPTOAPI_F_GET_PROC_ADDRESS, 0),                         "GetProcAddress" },
+    { ERR_PACK(0, CRYPTOAPI_F_NCRYPT_SIGN_HASH, 0),                         "NCryptSignHash" },
+    { 0, NULL }
+};
+
+/* Global EVP_PKEY_METHOD used to override the sign operation */
+static EVP_PKEY_METHOD *pmethod;
+static int (*default_pkey_sign_init) (EVP_PKEY_CTX *ctx);
+static int (*default_pkey_sign) (EVP_PKEY_CTX *ctx, unsigned char *sig,
+                                 size_t *siglen, const unsigned char *tbs, size_t tbslen);
+
+typedef struct _CAPI_DATA {
+    const CERT_CONTEXT *cert_context;
+    HCRYPTPROV_OR_NCRYPT_KEY_HANDLE crypt_prov;
+    DWORD key_spec;
+    BOOL free_crypt_prov;
+} CAPI_DATA;
+
+/**
+ * Translate OpenSSL padding type to CNG padding type
+ * Returns 0 for unknown/unsupported padding.
+ */
+static DWORD
+cng_padding_type(int padding)
+{
+    DWORD pad = 0;
+
+    switch (padding)
+    {
+        case RSA_NO_PADDING:
+            pad = BCRYPT_PAD_NONE;
+            break;
+
+        case RSA_PKCS1_PADDING:
+            pad = BCRYPT_PAD_PKCS1;
+            break;
+
+        case RSA_PKCS1_PSS_PADDING:
+            pad = BCRYPT_PAD_PSS;
+            break;
+
+        default:
+            msg(M_WARN|M_INFO, "cryptoapicert: unknown OpenSSL padding type %d.",
+                padding);
+    }
+
+    return pad;
+}
+
+/**
+ * Translate OpenSSL hash OID to CNG algorithm name. Returns
+ * "UNKNOWN" for unsupported algorithms and NULL for MD5+SHA1
+ * mixed hash used in TLS 1.1 and earlier.
+ */
+static const wchar_t *
+cng_hash_algo(int md_type)
+{
+    const wchar_t *alg = L"UNKNOWN";
+    switch (md_type)
+    {
+        case NID_md5:
+            alg = BCRYPT_MD5_ALGORITHM;
+            break;
+
+        case NID_sha1:
+            alg = BCRYPT_SHA1_ALGORITHM;
+            break;
+
+        case NID_sha256:
+            alg = BCRYPT_SHA256_ALGORITHM;
+            break;
+
+        case NID_sha384:
+            alg = BCRYPT_SHA384_ALGORITHM;
+            break;
+
+        case NID_sha512:
+            alg = BCRYPT_SHA512_ALGORITHM;
+            break;
+
+        case NID_md5_sha1:
+        case 0:
+            alg = NULL;
+            break;
+
+        default:
+            msg(M_WARN|M_INFO, "cryptoapicert: Unknown hash type NID=0x%x", md_type);
+            break;
+    }
+    return alg;
+}
+
+static char *
+ms_error_text(DWORD ms_err)
+{
+    LPVOID lpMsgBuf = NULL;
+    char *rv = NULL;
+
+    FormatMessage(
+        FORMAT_MESSAGE_ALLOCATE_BUFFER
+        |FORMAT_MESSAGE_FROM_SYSTEM
+        |FORMAT_MESSAGE_IGNORE_INSERTS,
+        NULL, ms_err,
+        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), /* Default language */
+        (LPTSTR) &lpMsgBuf, 0, NULL);
+    if (lpMsgBuf)
+    {
+        char *p;
+        rv = string_alloc(lpMsgBuf, NULL);
+        LocalFree(lpMsgBuf);
+        /* trim to the left */
+        if (rv)
+        {
+            for (p = rv + strlen(rv) - 1; p >= rv; p--) {
+                if (isspace(*p))
+                {
+                    *p = '\0';
+                }
+                else
+                {
+                    break;
+                }
+            }
+        }
+    }
+    return rv;
+}
+
+static void
+err_put_ms_error(DWORD ms_err, int func, const char *file, int line)
+{
+    static int init = 0;
+#define ERR_MAP_SZ 16
+    static struct {
+        int err;
+        DWORD ms_err;       /* I don't think we get more than 16 *different* errors */
+    } err_map[ERR_MAP_SZ];  /* in here, before we give up the whole thing...        */
+    int i;
+
+    if (ms_err == 0)
+    {
+        /* 0 is not an error */
+        return;
+    }
+    if (!init)
+    {
+        ERR_load_strings(ERR_LIB_CRYPTOAPI, CRYPTOAPI_str_functs);
+        memset(&err_map, 0, sizeof(err_map));
+        init++;
+    }
+    /* since MS error codes are 32 bit, and the ones in the ERR_... system is
+     * only 12, we must have a mapping table between them.  */
+    for (i = 0; i < ERR_MAP_SZ; i++) {
+        if (err_map[i].ms_err == ms_err)
+        {
+            ERR_PUT_error(ERR_LIB_CRYPTOAPI, func, err_map[i].err, file, line);
+            break;
+        }
+        else if (err_map[i].ms_err == 0)
+        {
+            /* end of table, add new entry */
+            ERR_STRING_DATA *esd = calloc(2, sizeof(*esd));
+            if (esd == NULL)
+            {
+                break;
+            }
+            err_map[i].ms_err = ms_err;
+            err_map[i].err = esd->error = i + 100;
+            esd->string = ms_error_text(ms_err);
+            check_malloc_return(esd->string);
+            ERR_load_strings(ERR_LIB_CRYPTOAPI, esd);
+            ERR_PUT_error(ERR_LIB_CRYPTOAPI, func, err_map[i].err, file, line);
+            break;
+        }
+    }
+}
+
+/* encrypt */
+static int
+rsa_pub_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    /* I haven't been able to trigger this one, but I want to know if it happens... */
+    assert(0);
+
+    return 0;
+}
+
+/* verify arbitrary data */
+static int
+rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    /* I haven't been able to trigger this one, but I want to know if it happens... */
+    assert(0);
+
+    return 0;
+}
+
+/**
+ * Sign the hash in 'from' using NCryptSignHash(). This requires an NCRYPT
+ * key handle in cd->crypt_prov. On return the signature is in 'to'. Returns
+ * the length of the signature or 0 on error.
+ * Only RSA is supported and padding should be BCRYPT_PAD_PKCS1 or
+ * BCRYPT_PAD_PSS.
+ * If the hash_algo is not NULL, PKCS #1 DigestInfo header gets added
+ * to |from|, else it is signed as is. Use NULL for MD5 + SHA1 hash used
+ * in TLS 1.1 and earlier.
+ * In case of PSS padding, |saltlen| should specify the size of salt to use.
+ * If |to| is NULL returns the required buffer size.
+ */
+static int
+priv_enc_CNG(const CAPI_DATA *cd, const wchar_t *hash_algo, const unsigned char *from,
+             int flen, unsigned char *to, int tlen, DWORD padding, DWORD saltlen)
+{
+    NCRYPT_KEY_HANDLE hkey = cd->crypt_prov;
+    DWORD len = 0;
+    ASSERT(cd->key_spec == CERT_NCRYPT_KEY_SPEC);
+
+    DWORD status;
+
+    msg(D_LOW, "Signing hash using CNG: data size = %d padding = %lu", flen, padding);
+
+    if (padding == BCRYPT_PAD_PKCS1)
+    {
+        BCRYPT_PKCS1_PADDING_INFO padinfo = {hash_algo};
+        status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen,
+                                to, tlen, &len, padding);
+    }
+    else if (padding == BCRYPT_PAD_PSS)
+    {
+        BCRYPT_PSS_PADDING_INFO padinfo = {hash_algo, saltlen};
+        status = NCryptSignHash(hkey, &padinfo, (BYTE *)from, flen,
+                                to, tlen, &len, padding);
+    }
+    else
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
+        return 0;
+    }
+
+    if (status != ERROR_SUCCESS)
+    {
+        SetLastError(status);
+        CRYPTOAPIerr(CRYPTOAPI_F_NCRYPT_SIGN_HASH);
+        len = 0;
+    }
+
+    /* Unlike CAPI, CNG signature is in big endian order. No reversing needed. */
+    return len;
+}
+
+/* sign arbitrary data */
+static int
+rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(RSA_get_method(rsa));
+    HCRYPTHASH hash;
+    DWORD hash_size, len, i;
+    unsigned char *buf;
+
+    if (cd == NULL)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
+    {
+        return priv_enc_CNG(cd, NULL, from, flen, to, RSA_size(rsa),
+                            cng_padding_type(padding), 0);
+    }
+
+    if (padding != RSA_PKCS1_PADDING)
+    {
+        /* AFAICS, CryptSignHash() *always* uses PKCS1 padding. */
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
+        return 0;
+    }
+
+    /* Unfortunately, there is no "CryptSign()" function in CryptoAPI, that would
+     * be way to straightforward for M$, I guess... So we have to do it this
+     * tricky way instead, by creating a "Hash", and load the already-made hash
+     * from 'from' into it.  */
+    /* For now, we only support NID_md5_sha1 */
+    if (flen != SSL_SIG_LENGTH)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_INVALID_MESSAGE_LENGTH);
+        return 0;
+    }
+    if (!CryptCreateHash(cd->crypt_prov, CALG_SSL3_SHAMD5, 0, 0, &hash))
+    {
+        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_CREATE_HASH);
+        return 0;
+    }
+    len = sizeof(hash_size);
+    if (!CryptGetHashParam(hash, HP_HASHSIZE, (BYTE *) &hash_size, &len, 0))
+    {
+        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_GET_HASH_PARAM);
+        CryptDestroyHash(hash);
+        return 0;
+    }
+    if ((int) hash_size != flen)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_INVALID_MESSAGE_LENGTH);
+        CryptDestroyHash(hash);
+        return 0;
+    }
+    if (!CryptSetHashParam(hash, HP_HASHVAL, (BYTE * ) from, 0))
+    {
+        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_SET_HASH_PARAM);
+        CryptDestroyHash(hash);
+        return 0;
+    }
+
+    len = RSA_size(rsa);
+    buf = malloc(len);
+    if (buf == NULL)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_MALLOC_FAILURE);
+        CryptDestroyHash(hash);
+        return 0;
+    }
+    if (!CryptSignHash(hash, cd->key_spec, NULL, 0, buf, &len))
+    {
+        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_SIGN_HASH);
+        CryptDestroyHash(hash);
+        free(buf);
+        return 0;
+    }
+    /* and now, we have to reverse the byte-order in the result from CryptSignHash()... */
+    for (i = 0; i < len; i++)
+    {
+        to[i] = buf[len - i - 1];
+    }
+    free(buf);
+
+    CryptDestroyHash(hash);
+    return len;
+}
+
+/**
+ * Sign the hash in |m| and return the signature in |sig|.
+ * Returns 1 on success, 0 on error.
+ * NCryptSignHash() is used to sign and it is instructed to add the
+ * the PKCS #1 DigestInfo header to |m| unless the hash algorithm is
+ * the MD5/SHA1 combination used in TLS 1.1 and earlier versions.
+ * OpenSSL exercises this callback only when padding is PKCS1 v1.5.
+ */
+static int
+rsa_sign_CNG(int type, const unsigned char *m, unsigned int m_len,
+              unsigned char *sig, unsigned int *siglen, const RSA *rsa)
+{
+    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(RSA_get_method(rsa));
+    const wchar_t *alg = NULL;
+    int padding = RSA_PKCS1_PADDING;
+
+    *siglen = 0;
+    if (cd == NULL)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, ERR_R_PASSED_NULL_PARAMETER);
+        return 0;
+    }
+
+    alg = cng_hash_algo(type);
+    if (alg && wcscmp(alg, L"UNKNOWN") == 0)
+    {
+        RSAerr(RSA_F_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
+        return 0;
+    }
+
+    *siglen = priv_enc_CNG(cd, alg, m, (int)m_len, sig, RSA_size(rsa),
+                           cng_padding_type(padding), 0);
+
+    return (*siglen == 0) ? 0 : 1;
+}
+
+/* decrypt */
+static int
+rsa_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    /* I haven't been able to trigger this one, but I want to know if it happens... */
+    assert(0);
+
+    return 0;
+}
+
+/* called at RSA_new */
+static int
+init(RSA *rsa)
+{
+
+    return 0;
+}
+
+/* called at RSA_free */
+static int
+finish(RSA *rsa)
+{
+    const RSA_METHOD *rsa_meth = RSA_get_method(rsa);
+    CAPI_DATA *cd = (CAPI_DATA *) RSA_meth_get0_app_data(rsa_meth);
+
+    if (cd == NULL)
+    {
+        return 0;
+    }
+    if (cd->crypt_prov && cd->free_crypt_prov)
+    {
+        if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
+        {
+            NCryptFreeObject(cd->crypt_prov);
+        }
+        else
+        {
+            CryptReleaseContext(cd->crypt_prov, 0);
+        }
+    }
+    if (cd->cert_context)
+    {
+        CertFreeCertificateContext(cd->cert_context);
+    }
+    free(cd);
+    RSA_meth_free((RSA_METHOD*) rsa_meth);
+    return 1;
+}
+
+static const CERT_CONTEXT *
+find_certificate_in_store(const char *cert_prop, HCERTSTORE cert_store)
+{
+    /* Find, and use, the desired certificate from the store. The
+     * 'cert_prop' certificate search string can look like this:
+     * SUBJ:<certificate substring to match>
+     * THUMB:<certificate thumbprint hex value>, e.g.
+     *     THUMB:f6 49 24 41 01 b4 fb 44 0c ce f4 36 ae d0 c4 c9 df 7a b6 28
+     * The first matching certificate that has not expired is returned.
+     */
+    const CERT_CONTEXT *rv = NULL;
+    DWORD find_type;
+    const void *find_param;
+    unsigned char hash[255];
+    CRYPT_HASH_BLOB blob = {.cbData = 0, .pbData = hash};
+    struct gc_arena gc = gc_new();
+
+    if (!strncmp(cert_prop, "SUBJ:", 5))
+    {
+        /* skip the tag */
+        find_param = wide_string(cert_prop + 5, &gc);
+        find_type = CERT_FIND_SUBJECT_STR_W;
+    }
+    else if (!strncmp(cert_prop, "THUMB:", 6))
+    {
+        const char *p;
+        int i, x = 0;
+        find_type = CERT_FIND_HASH;
+        find_param = &blob;
+
+        /* skip the tag */
+        cert_prop += 6;
+        for (p = cert_prop, i = 0; *p && i < sizeof(hash); i++)
+        {
+            if (*p >= '0' && *p <= '9')
+            {
+                x = (*p - '0') << 4;
+            }
+            else if (*p >= 'A' && *p <= 'F')
+            {
+                x = (*p - 'A' + 10) << 4;
+            }
+            else if (*p >= 'a' && *p <= 'f')
+            {
+                x = (*p - 'a' + 10) << 4;
+            }
+            if (!*++p)  /* unexpected end of string */
+            {
+                msg(M_WARN, "WARNING: cryptoapicert: error parsing <THUMB:%s>.", cert_prop);
+                goto out;
+            }
+            if (*p >= '0' && *p <= '9')
+            {
+                x += *p - '0';
+            }
+            else if (*p >= 'A' && *p <= 'F')
+            {
+                x += *p - 'A' + 10;
+            }
+            else if (*p >= 'a' && *p <= 'f')
+            {
+                x += *p - 'a' + 10;
+            }
+            hash[i] = x;
+            /* skip any space(s) between hex numbers */
+            for (p++; *p && *p == ' '; p++)
+            {
+            }
+        }
+        blob.cbData = i;
+    }
+    else
+    {
+        msg(M_WARN, "WARNING: cryptoapicert: unsupported certificate specification <%s>", cert_prop);
+        goto out;
+    }
+
+    while(true)
+    {
+        int validity = 1;
+        /* this frees previous rv, if not NULL */
+        rv = CertFindCertificateInStore(cert_store, X509_ASN_ENCODING | PKCS_7_ASN_ENCODING,
+                                        0, find_type, find_param, rv);
+        if (rv)
+        {
+            validity = CertVerifyTimeValidity(NULL, rv->pCertInfo);
+        }
+        if (!rv || validity == 0)
+        {
+            break;
+        }
+        msg(M_WARN, "WARNING: cryptoapicert: ignoring certificate in store %s.",
+            validity < 0 ? "not yet valid" : "that has expired");
+    }
+
+out:
+    gc_free(&gc);
+    return rv;
+}
+
+#if (OPENSSL_VERSION_NUMBER >= 0x10100000L)
+
+static const CAPI_DATA *
+retrieve_capi_data(EVP_PKEY *pkey)
+{
+    const CAPI_DATA *cd = NULL;
+
+    if (pkey && EVP_PKEY_id(pkey) == EVP_PKEY_RSA)
+    {
+        RSA *rsa = EVP_PKEY_get0_RSA(pkey);
+        if (rsa)
+        {
+            cd = (CAPI_DATA *)RSA_meth_get0_app_data(RSA_get_method(rsa));
+        }
+    }
+    return cd;
+}
+
+static int
+pkey_rsa_sign_init(EVP_PKEY_CTX *ctx)
+{
+    EVP_PKEY *pkey = EVP_PKEY_CTX_get0_pkey(ctx);
+
+    if (pkey && retrieve_capi_data(pkey))
+    {
+        return 1; /* Return success */
+    }
+    else if (default_pkey_sign_init)  /* Not our key. Call the default method */
+    {
+        return default_pkey_sign_init(ctx);
+    }
+    return 1;
+}
+
+/**
+ * Implementation of EVP_PKEY_sign() using CNG: sign the digest in |tbs|
+ * and save the the signature in |sig| and its size in |*siglen|.
+ * If |sig| is NULL the required buffer size is returned in |*siglen|.
+ * Returns 1 on success, 0 or a negative integer on error.
+ */
+static int
+pkey_rsa_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
+              const unsigned char *tbs, size_t tbslen)
+{
+    EVP_PKEY *pkey = NULL;
+    const CAPI_DATA *cd = NULL;
+    EVP_MD *md = NULL;
+    const wchar_t *alg = NULL;
+
+    int padding;
+    int hashlen;
+    int saltlen;
+
+    pkey = EVP_PKEY_CTX_get0_pkey(ctx);
+    if (pkey)
+    {
+        cd = retrieve_capi_data(pkey);
+    }
+
+    /*
+     * We intercept all sign requests, not just the one's for our key.
+     * Check the key and call the saved OpenSSL method for unknown keys.
+     */
+    if (!pkey || !cd)
+    {
+        if (default_pkey_sign)
+        {
+            return default_pkey_sign(ctx, sig, siglen, tbs, tbslen);
+        }
+        else  /* This should not happen */
+        {
+            msg(M_FATAL, "cryptopaicert: Unknown key and no default sign operation to fallback on");
+            return -1;
+        }
+    }
+
+    if (!EVP_PKEY_CTX_get_rsa_padding(ctx, &padding))
+    {
+        padding = RSA_PKCS1_PADDING; /* Default padding for RSA */
+    }
+
+    if (EVP_PKEY_CTX_get_signature_md(ctx, &md))
+    {
+        hashlen = EVP_MD_size(md);
+        alg = cng_hash_algo(EVP_MD_type(md));
+
+        /*
+         * alg == NULL indicates legacy MD5+SHA1 hash, else alg should be a valid
+         * digest algorithm.
+         */
+        if (alg && wcscmp(alg, L"UNKNOWN") == 0)
+        {
+            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
+            return -1;
+        }
+    }
+    else
+    {
+        msg(M_NONFATAL, "cryptoapicert: could not determine the signature digest algorithm");
+        RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNKNOWN_ALGORITHM_TYPE);
+        return -1;
+    }
+
+    if (tbslen != (size_t)hashlen)
+    {
+        RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_INVALID_DIGEST_LENGTH);
+        return -1;
+    }
+
+    /* If padding is PSS, determine parameters to pass to CNG */
+    if (padding == RSA_PKCS1_PSS_PADDING)
+    {
+        /*
+         * Ensure the digest type for signature and mask generation match.
+         * In CNG there is no option to specify separate hash functions for
+         * the two, but OpenSSL supports it. However, I have not seen the
+         * two being different in practice. Also the recommended practice is
+         * to use the same for both (rfc 8017 sec 8.1).
+         */
+        EVP_MD *mgf1md;
+        if (!EVP_PKEY_CTX_get_rsa_mgf1_md(ctx, &mgf1md)
+            || EVP_MD_type(mgf1md) != EVP_MD_type(md))
+        {
+            msg(M_NONFATAL, "cryptoapicert: Unknown MGF1 digest type or does"
+                " not match the signature digest type.");
+            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_UNSUPPORTED_MASK_PARAMETER);
+        }
+
+        if (!EVP_PKEY_CTX_get_rsa_pss_saltlen(ctx, &saltlen))
+        {
+            msg(M_WARN|M_INFO, "cryptoapicert: unable to get the salt length from context."
+                " Using the default value.");
+            saltlen = -1;
+        }
+
+        /*
+         * In OpenSSL saltlen = -1 indicates to use the size of the digest as
+         * size of the salt. A value of -2 or -3 indicates maximum salt length
+         * that will fit. See RSA_padding_add_PKCS1_PSS_mgf1() of OpenSSL.
+         */
+        if (saltlen == -1)
+        {
+            saltlen = hashlen;
+        }
+        else if (saltlen < 0)
+        {
+            const RSA *rsa = EVP_PKEY_get0_RSA(pkey);
+            saltlen = RSA_size(rsa) - hashlen - 2; /* max salt length for RSASSA-PSS */
+            if (RSA_bits(rsa) &0x7) /* number of bits in the key not a multiple of 8 */
+            {
+                saltlen--;
+            }
+        }
+
+        if (saltlen < 0)
+        {
+            RSAerr(RSA_F_PKEY_RSA_SIGN, RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
+            return -1;
+        }
+        msg(D_LOW, "cryptoapicert: PSS padding using saltlen = %d", saltlen);
+    }
+
+    *siglen = priv_enc_CNG(cd, alg, tbs, (int)tbslen, sig, *siglen,
+                           cng_padding_type(padding), (DWORD)saltlen);
+
+    return (*siglen == 0) ? 0 : 1;
+}
+
+#endif /* OPENSSL_VERSION >= 1.1.0 */
+
+int
+SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop)
+{
+    HCERTSTORE cs;
+    X509 *cert = NULL;
+    RSA *rsa = NULL, *pub_rsa;
+    CAPI_DATA *cd = calloc(1, sizeof(*cd));
+    RSA_METHOD *my_rsa_method = NULL;
+
+    if (cd == NULL)
+    {
+        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+    /* search CURRENT_USER first, then LOCAL_MACHINE */
+    cs = CertOpenStore((LPCSTR) CERT_STORE_PROV_SYSTEM, 0, 0, CERT_SYSTEM_STORE_CURRENT_USER
+                       |CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG, L"MY");
+    if (cs == NULL)
+    {
+        CRYPTOAPIerr(CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE);
+        goto err;
+    }
+    cd->cert_context = find_certificate_in_store(cert_prop, cs);
+    CertCloseStore(cs, 0);
+    if (!cd->cert_context)
+    {
+        cs = CertOpenStore((LPCSTR) CERT_STORE_PROV_SYSTEM, 0, 0, CERT_SYSTEM_STORE_LOCAL_MACHINE
+                           |CERT_STORE_OPEN_EXISTING_FLAG | CERT_STORE_READONLY_FLAG, L"MY");
+        if (cs == NULL)
+        {
+            CRYPTOAPIerr(CRYPTOAPI_F_CERT_OPEN_SYSTEM_STORE);
+            goto err;
+        }
+        cd->cert_context = find_certificate_in_store(cert_prop, cs);
+        CertCloseStore(cs, 0);
+        if (cd->cert_context == NULL)
+        {
+            CRYPTOAPIerr(CRYPTOAPI_F_CERT_FIND_CERTIFICATE_IN_STORE);
+            goto err;
+        }
+    }
+
+    /* cert_context->pbCertEncoded is the cert X509 DER encoded. */
+    cert = d2i_X509(NULL, (const unsigned char **) &cd->cert_context->pbCertEncoded,
+                    cd->cert_context->cbCertEncoded);
+    if (cert == NULL)
+    {
+        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_ASN1_LIB);
+        goto err;
+    }
+
+    /* set up stuff to use the private key */
+    /* We prefer to get an NCRYPT key handle so that TLS1.2 can be supported */
+    DWORD flags = CRYPT_ACQUIRE_COMPARE_KEY_FLAG
+                  | CRYPT_ACQUIRE_PREFER_NCRYPT_KEY_FLAG;
+    if (!CryptAcquireCertificatePrivateKey(cd->cert_context, flags, NULL,
+                    &cd->crypt_prov, &cd->key_spec, &cd->free_crypt_prov))
+    {
+        /* if we don't have a smart card reader here, and we try to access a
+         * smart card certificate, we get:
+         * "Error 1223: The operation was canceled by the user." */
+        CRYPTOAPIerr(CRYPTOAPI_F_CRYPT_ACQUIRE_CERTIFICATE_PRIVATE_KEY);
+        goto err;
+    }
+    /* here we don't need to do CryptGetUserKey() or anything; all necessary key
+     * info is in cd->cert_context, and then, in cd->crypt_prov.  */
+
+    /* if we do not have an NCRYPT key handle restrict TLS to v1.1 or lower */
+    int max_version = SSL_CTX_get_max_proto_version(ssl_ctx);
+    if ((!max_version || max_version > TLS1_1_VERSION)
+        && cd->key_spec != CERT_NCRYPT_KEY_SPEC)
+    {
+        msg(M_WARN, "WARNING: cryptoapicert: private key is in a legacy store."
+            " Restricting TLS version to 1.1");
+        if (SSL_CTX_get_min_proto_version(ssl_ctx) > TLS1_1_VERSION)
+        {
+            msg(M_NONFATAL,
+                "ERROR: cryptoapicert: min TLS version larger than 1.1."
+                " Try config option --tls-version-min 1.1");
+            goto err;
+        }
+        if (!SSL_CTX_set_max_proto_version(ssl_ctx, TLS1_1_VERSION))
+        {
+            msg(M_NONFATAL, "ERROR: cryptoapicert: set max TLS version failed");
+            goto err;
+        }
+    }
+
+    my_rsa_method = RSA_meth_new("Microsoft Cryptography API RSA Method",
+                                  RSA_METHOD_FLAG_NO_CHECK);
+    check_malloc_return(my_rsa_method);
+    RSA_meth_set_pub_enc(my_rsa_method, rsa_pub_enc);
+    RSA_meth_set_pub_dec(my_rsa_method, rsa_pub_dec);
+    RSA_meth_set_priv_enc(my_rsa_method, rsa_priv_enc);
+    RSA_meth_set_priv_dec(my_rsa_method, rsa_priv_dec);
+    RSA_meth_set_init(my_rsa_method, NULL);
+    RSA_meth_set_finish(my_rsa_method, finish);
+    RSA_meth_set0_app_data(my_rsa_method, cd);
+
+    /* For CNG, set the RSA_sign method which gets priority over priv_enc().
+     * This method is called with the raw hash without the digestinfo
+     * header and works better when using NCryptSignHash() with some tokens.
+     * However, if PSS padding is in use, openssl does not call this
+     * function but adds the padding and then calls rsa_priv_enc()
+     * with padding set to NONE which is not supported by CNG.
+     * So, when posisble (OpenSSL 1.1.0 and up), we hook on to the sign
+     * operation in EVP_PKEY_METHOD struct.
+     */
+    if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
+    {
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L)
+        RSA_meth_set_sign(my_rsa_method, rsa_sign_CNG);
+#else
+        /* pmethod is global -- initialize only if NULL */
+        if (!pmethod)
+        {
+            pmethod = EVP_PKEY_meth_new(EVP_PKEY_RSA, 0);
+            if (!pmethod)
+            {
+                SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
+                goto err;
+            }
+            const EVP_PKEY_METHOD *default_pmethod = EVP_PKEY_meth_find(EVP_PKEY_RSA);
+            EVP_PKEY_meth_copy(pmethod, default_pmethod);
+
+            /* We want to override only sign_init() and sign() */
+            EVP_PKEY_meth_set_sign(pmethod, pkey_rsa_sign_init, pkey_rsa_sign);
+            EVP_PKEY_meth_add0(pmethod);
+
+            /* Keep a copy of the default sign and sign_init methods */
+
+#if (OPENSSL_VERSION_NUMBER < 0x1010009fL)   /* < version 1.1.0i */
+            /* The function signature is not const-correct in these versions */
+            EVP_PKEY_meth_get_sign((EVP_PKEY_METHOD *)default_pmethod, &default_pkey_sign_init,
+                                   &default_pkey_sign);
+#else
+            EVP_PKEY_meth_get_sign(default_pmethod, &default_pkey_sign_init,
+                                   &default_pkey_sign);
+#endif
+        }
+#endif /* (OPENSSL_VERSION_NUMBER < 0x10100000L) */
+    }
+
+    rsa = RSA_new();
+    if (rsa == NULL)
+    {
+        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    /* Public key in cert is NULL until we call SSL_CTX_use_certificate(),
+     * so we do it here then...  */
+    if (!SSL_CTX_use_certificate(ssl_ctx, cert))
+    {
+        goto err;
+    }
+    /* the public key */
+    EVP_PKEY *pkey = X509_get0_pubkey(cert);
+
+    /* SSL_CTX_use_certificate() increased the reference count in 'cert', so
+     * we decrease it here with X509_free(), or it will never be cleaned up. */
+    X509_free(cert);
+    cert = NULL;
+
+    if (!(pub_rsa = EVP_PKEY_get0_RSA(pkey)))
+    {
+        msg(M_WARN, "cryptoapicert requires an RSA certificate");
+        goto err;
+    }
+
+    /* Our private key is external, so we fill in only n and e from the public key */
+    const BIGNUM *n = NULL;
+    const BIGNUM *e = NULL;
+    RSA_get0_key(pub_rsa, &n, &e, NULL);
+    if (!RSA_set0_key(rsa, BN_dup(n), BN_dup(e), NULL))
+    {
+        goto err;
+    }
+    RSA_set_flags(rsa, RSA_flags(rsa) | RSA_FLAG_EXT_PKEY);
+    if (!RSA_set_method(rsa, my_rsa_method))
+    {
+        goto err;
+    }
+
+    if (!SSL_CTX_use_RSAPrivateKey(ssl_ctx, rsa))
+    {
+        goto err;
+    }
+    /* SSL_CTX_use_RSAPrivateKey() increased the reference count in 'rsa', so
+    * we decrease it here with RSA_free(), or it will never be cleaned up. */
+    RSA_free(rsa);
+    return 1;
+
+err:
+    if (cert)
+    {
+        X509_free(cert);
+    }
+    if (rsa)
+    {
+        RSA_free(rsa);
+    }
+    else
+    {
+        if (my_rsa_method)
+        {
+            free(my_rsa_method);
+        }
+        if (cd)
+        {
+            if (cd->free_crypt_prov && cd->crypt_prov)
+            {
+                if (cd->key_spec == CERT_NCRYPT_KEY_SPEC)
+                {
+                    NCryptFreeObject(cd->crypt_prov);
+                }
+                else
+                {
+                    CryptReleaseContext(cd->crypt_prov, 0);
+                }
+            }
+            if (cd->cert_context)
+            {
+                CertFreeCertificateContext(cd->cert_context);
+            }
+            free(cd);
+        }
+    }
+    return 0;
+}
+
+#else  /* ifdef ENABLE_CRYPTOAPI */
+#ifdef _MSC_VER  /* Dummy function needed to avoid empty file compiler warning in Microsoft VC */
+static void
+dummy(void)
+{
+}
+#endif
+#endif                          /* _WIN32 */
diff --git a/src/openvpn/cryptoapi.h b/src/openvpn/cryptoapi.h
new file mode 100644
index 0000000..8ac6db3
--- /dev/null
+++ b/src/openvpn/cryptoapi.h
@@ -0,0 +1,7 @@
+#ifndef _CRYPTOAPI_H_
+#define _CRYPTOAPI_H_
+
+int SSL_CTX_use_CryptoAPI_certificate(SSL_CTX *ssl_ctx, const char *cert_prop);
+
+
+#endif /* !_CRYPTOAPI_H_ */
diff --git a/src/openvpn/dhcp.c b/src/openvpn/dhcp.c
new file mode 100644
index 0000000..fb28b27
--- /dev/null
+++ b/src/openvpn/dhcp.c
@@ -0,0 +1,233 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "dhcp.h"
+#include "socket.h"
+#include "error.h"
+
+#include "memdbg.h"
+
+static int
+get_dhcp_message_type(const struct dhcp *dhcp, const int optlen)
+{
+    const uint8_t *p = (uint8_t *) (dhcp + 1);
+    int i;
+
+    for (i = 0; i < optlen; ++i)
+    {
+        const uint8_t type = p[i];
+        const int room = optlen - i;
+        if (type == DHCP_END)         /* didn't find what we were looking for */
+        {
+            return -1;
+        }
+        else if (type == DHCP_PAD)    /* no-operation */
+        {
+        }
+        else if (type == DHCP_MSG_TYPE) /* what we are looking for */
+        {
+            if (room >= 3)
+            {
+                if (p[i+1] == 1)      /* option length should be 1 */
+                {
+                    return p[i+2];    /* return message type */
+                }
+            }
+            return -1;
+        }
+        else                          /* some other option */
+        {
+            if (room >= 2)
+            {
+                const int len = p[i+1]; /* get option length */
+                i += (len + 1);       /* advance to next option */
+            }
+        }
+    }
+    return -1;
+}
+
+static in_addr_t
+do_extract(struct dhcp *dhcp, int optlen)
+{
+    uint8_t *p = (uint8_t *) (dhcp + 1);
+    int i;
+    in_addr_t ret = 0;
+
+    for (i = 0; i < optlen; )
+    {
+        const uint8_t type = p[i];
+        const int room = optlen - i;
+        if (type == DHCP_END)
+        {
+            break;
+        }
+        else if (type == DHCP_PAD)
+        {
+            ++i;
+        }
+        else if (type == DHCP_ROUTER)
+        {
+            if (room >= 2)
+            {
+                const int len = p[i+1]; /* get option length */
+                if (len <= (room-2))
+                {
+                    /* get router IP address */
+                    if (!ret && len >= 4 && (len & 3) == 0)
+                    {
+                        memcpy(&ret, p+i+2, 4);
+                        ret = ntohl(ret);
+                    }
+                    {
+                        /* delete the router option */
+                        uint8_t *dest = p + i;
+                        const int owlen = len + 2;        /* len of data to overwrite */
+                        uint8_t *src = dest + owlen;
+                        uint8_t *end = p + optlen;
+                        const int movlen = end - src;
+                        if (movlen > 0)
+                        {
+                            memmove(dest, src, movlen);   /* overwrite router option */
+                        }
+                        memset(end - owlen, DHCP_PAD, owlen); /* pad tail */
+                    }
+                }
+                else
+                {
+                    break;
+                }
+            }
+            else
+            {
+                break;
+            }
+        }
+        else                            /* some other option */
+        {
+            if (room >= 2)
+            {
+                const int len = p[i+1]; /* get option length */
+                i += (len + 2);         /* advance to next option */
+            }
+            else
+            {
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+static uint16_t
+udp_checksum(const uint8_t *buf,
+             const int len_udp,
+             const uint8_t *src_addr,
+             const uint8_t *dest_addr)
+{
+    uint16_t word16;
+    uint32_t sum = 0;
+    int i;
+
+    /* make 16 bit words out of every two adjacent 8 bit words and  */
+    /* calculate the sum of all 16 bit words */
+    for (i = 0; i < len_udp; i += 2)
+    {
+        word16 = ((buf[i] << 8) & 0xFF00) + ((i + 1 < len_udp) ? (buf[i+1] & 0xFF) : 0);
+        sum += word16;
+    }
+
+    /* add the UDP pseudo header which contains the IP source and destination addresses */
+    for (i = 0; i < 4; i += 2)
+    {
+        word16 = ((src_addr[i] << 8) & 0xFF00) + (src_addr[i+1] & 0xFF);
+        sum += word16;
+    }
+    for (i = 0; i < 4; i += 2)
+    {
+        word16 = ((dest_addr[i] << 8) & 0xFF00) + (dest_addr[i+1] & 0xFF);
+        sum += word16;
+    }
+
+    /* the protocol number and the length of the UDP packet */
+    sum += (uint16_t) OPENVPN_IPPROTO_UDP + (uint16_t) len_udp;
+
+    /* keep only the last 16 bits of the 32 bit calculated sum and add the carries */
+    while (sum >> 16)
+    {
+        sum = (sum & 0xFFFF) + (sum >> 16);
+    }
+
+    /* Take the one's complement of sum */
+    return ((uint16_t) ~sum);
+}
+
+in_addr_t
+dhcp_extract_router_msg(struct buffer *ipbuf)
+{
+    struct dhcp_full *df = (struct dhcp_full *) BPTR(ipbuf);
+    const int optlen = BLEN(ipbuf) - (sizeof(struct openvpn_iphdr) + sizeof(struct openvpn_udphdr) + sizeof(struct dhcp));
+
+    if (optlen >= 0
+        && df->ip.protocol == OPENVPN_IPPROTO_UDP
+        && df->udp.source == htons(BOOTPS_PORT)
+        && df->udp.dest == htons(BOOTPC_PORT)
+        && df->dhcp.op == BOOTREPLY)
+    {
+        const int message_type = get_dhcp_message_type(&df->dhcp, optlen);
+        if (message_type == DHCPACK || message_type == DHCPOFFER)
+        {
+            /* get the router IP address while padding out all DHCP router options */
+            const in_addr_t ret = do_extract(&df->dhcp, optlen);
+
+            /* recompute the UDP checksum */
+            df->udp.check = 0;
+            df->udp.check = htons(udp_checksum((uint8_t *) &df->udp,
+                                               sizeof(struct openvpn_udphdr) + sizeof(struct dhcp) + optlen,
+                                               (uint8_t *)&df->ip.saddr,
+                                               (uint8_t *)&df->ip.daddr));
+
+            /* only return the extracted Router address if DHCPACK */
+            if (message_type == DHCPACK)
+            {
+                if (ret)
+                {
+                    struct gc_arena gc = gc_new();
+                    msg(D_ROUTE, "Extracted DHCP router address: %s", print_in_addr_t(ret, 0, &gc));
+                    gc_free(&gc);
+                }
+
+                return ret;
+            }
+        }
+    }
+    return 0;
+}
diff --git a/src/openvpn/dhcp.h b/src/openvpn/dhcp.h
new file mode 100644
index 0000000..32aa15e
--- /dev/null
+++ b/src/openvpn/dhcp.h
@@ -0,0 +1,86 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef DHCP_H
+#define DHCP_H
+
+#include "common.h"
+#include "buffer.h"
+#include "proto.h"
+
+#pragma pack(1)
+
+/* DHCP Option types */
+#define DHCP_PAD          0
+#define DHCP_ROUTER       3
+#define DHCP_MSG_TYPE    53  /* message type (u8) */
+#define DHCP_END        255
+
+/* DHCP Messages types */
+#define DHCPDISCOVER 1
+#define DHCPOFFER    2
+#define DHCPREQUEST  3
+#define DHCPDECLINE  4
+#define DHCPACK      5
+#define DHCPNAK      6
+#define DHCPRELEASE  7
+#define DHCPINFORM   8
+
+/* DHCP UDP port numbers */
+#define BOOTPS_PORT 67
+#define BOOTPC_PORT 68
+
+struct dhcp {
+#define BOOTREQUEST 1
+#define BOOTREPLY   2
+    uint8_t op;        /* message op */
+
+    uint8_t htype;     /* hardware address type (e.g. '1' = 10Mb Ethernet) */
+    uint8_t hlen;      /* hardware address length (e.g. '6' for 10Mb Ethernet) */
+    uint8_t hops;      /* client sets to 0, may be used by relay agents */
+    uint32_t xid;      /* transaction ID, chosen by client */
+    uint16_t secs;     /* seconds since request process began, set by client */
+    uint16_t flags;
+    uint32_t ciaddr;   /* client IP address, client sets if known */
+    uint32_t yiaddr;   /* 'your' IP address -- server's response to client */
+    uint32_t siaddr;   /* server IP address */
+    uint32_t giaddr;   /* relay agent IP address */
+    uint8_t chaddr[16]; /* client hardware address */
+    uint8_t sname[64]; /* optional server host name */
+    uint8_t file[128]; /* boot file name */
+    uint32_t magic;    /* must be 0x63825363 (network order) */
+};
+
+struct dhcp_full {
+    struct openvpn_iphdr ip;
+    struct openvpn_udphdr udp;
+    struct dhcp dhcp;
+#define DHCP_OPTIONS_BUFFER_SIZE 256
+    uint8_t options[DHCP_OPTIONS_BUFFER_SIZE];
+};
+
+#pragma pack()
+
+in_addr_t dhcp_extract_router_msg(struct buffer *ipbuf);
+
+#endif /* ifndef DHCP_H */
diff --git a/src/openvpn/errlevel.h b/src/openvpn/errlevel.h
new file mode 100644
index 0000000..5ca4fa8
--- /dev/null
+++ b/src/openvpn/errlevel.h
@@ -0,0 +1,178 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef ERRLEVEL_H
+#define ERRLEVEL_H
+
+#include "error.h"
+
+/*
+ * Debug level at and above where we
+ * display time to microsecond resolution.
+ */
+#define DEBUG_LEVEL_USEC_TIME 4
+
+/*
+ * In non-server modes, delay n milliseconds after certain kinds
+ * of non-fatal network errors to avoid a barrage of errors.
+ *
+ * To disable all delays, set to 0.
+ */
+#define P2P_ERROR_DELAY_MS 0
+
+/*
+ * Enable D_LOG_RW
+ */
+#define LOG_RW
+
+/*
+ * Debugging levels for various kinds
+ * of output.
+ */
+
+#define M_VERB0              LOGLEV(0, 0, 0)         /* Messages displayed even at --verb 0 (fatal errors only) */
+
+#define M_INFO               LOGLEV(1, 0, 0)         /* default informational messages */
+
+#define D_LINK_ERRORS        LOGLEV(1, 1, M_NONFATAL)   /* show link errors from main event loop */
+#define D_CRYPT_ERRORS       LOGLEV(1, 2, M_NONFATAL)   /* show errors from encrypt/decrypt */
+#define D_TLS_ERRORS         LOGLEV(1, 3, M_NONFATAL)   /* show TLS control channel errors */
+#define D_RESOLVE_ERRORS     LOGLEV(1, 4, M_NONFATAL)   /* show hostname resolve errors */
+#define D_COMP_ERRORS        LOGLEV(1, 5, M_NONFATAL)   /* show compression errors */
+#define D_REPLAY_ERRORS      LOGLEV(1, 6, M_NONFATAL)   /* show packet replay errors */
+#define D_STREAM_ERRORS      LOGLEV(1, 7, M_NONFATAL)    /* TCP stream error requiring restart */
+#define D_IMPORT_ERRORS      LOGLEV(1, 8, M_NONFATAL)    /* show server import option errors */
+#define D_MULTI_ERRORS       LOGLEV(1, 9, M_NONFATAL)    /* show multi-client server errors */
+#define D_EVENT_ERRORS       LOGLEV(1, 10, M_NONFATAL)   /* show event.[ch] errors */
+#define D_PUSH_ERRORS        LOGLEV(1, 11, M_NONFATAL)   /* show push/pull errors */
+#define D_PID_PERSIST        LOGLEV(1, 12, M_NONFATAL)   /* show packet_id persist errors */
+#define D_FRAG_ERRORS        LOGLEV(1, 13, M_NONFATAL)   /* show fragmentation errors */
+#define D_ALIGN_ERRORS       LOGLEV(1, 14, M_NONFATAL)   /* show bad struct alignments */
+
+#define D_HANDSHAKE          LOGLEV(2, 20, 0)        /* show data & control channel handshakes */
+#define D_CLOSE              LOGLEV(2, 22, 0)        /* show socket and TUN/TAP close */
+#define D_PROXY              LOGLEV(2, 24, 0)        /* show http proxy control packets */
+#define D_ARGV               LOGLEV(2, 25, 0)        /* show struct argv errors */
+
+#define D_TLS_DEBUG_LOW      LOGLEV(3, 20, 0)        /* low frequency info from tls_session routines */
+#define D_GREMLIN            LOGLEV(3, 30, 0)        /* show simulated outage info from gremlin module */
+#define D_GENKEY             LOGLEV(3, 31, 0)        /* print message after key generation */
+#define D_ROUTE              LOGLEV(3, 0,  0)        /* show routes added and deleted (don't mute) */
+#define D_TUNTAP_INFO        LOGLEV(3, 32, 0)        /* show debugging info from TUN/TAP driver */
+#define D_RESTART            LOGLEV(3, 33, 0)        /* show certain restart messages */
+#define D_PUSH               LOGLEV(3, 34, 0)        /* show push/pull info */
+#define D_IFCONFIG_POOL      LOGLEV(3, 35, 0)        /* show ifconfig pool info */
+#define D_AUTH               LOGLEV(3, 37, 0)        /* show user/pass auth info */
+#define D_MULTI_LOW          LOGLEV(3, 38, 0)        /* show point-to-multipoint low-freq debug info */
+#define D_PLUGIN             LOGLEV(3, 39, 0)        /* show plugin calls */
+#define D_MANAGEMENT         LOGLEV(3, 40, 0)        /* show --management info */
+#define D_SCHED_EXIT         LOGLEV(3, 41, 0)        /* show arming of scheduled exit */
+#define D_ROUTE_QUOTA        LOGLEV(3, 42, 0)        /* show route quota exceeded messages */
+#define D_OSBUF              LOGLEV(3, 43, 0)        /* show socket/tun/tap buffer sizes */
+#define D_PS_PROXY           LOGLEV(3, 44, 0)        /* messages related to --port-share option */
+#define D_PF_INFO            LOGLEV(3, 45, 0)        /* packet filter informational messages */
+
+#define D_SHOW_PARMS         LOGLEV(4, 50, 0)        /* show all parameters on program initiation */
+#define D_SHOW_OCC           LOGLEV(4, 51, 0)        /* show options compatibility string */
+#define D_LOW                LOGLEV(4, 52, 0)        /* miscellaneous low-frequency debug info */
+#define D_DHCP_OPT           LOGLEV(4, 53, 0)        /* show DHCP options binary string */
+#define D_MBUF               LOGLEV(4, 54, 0)        /* mbuf.[ch] routines */
+#define D_PACKET_TRUNC_ERR   LOGLEV(4, 55, 0)        /* PACKET_TRUNCATION_CHECK */
+#define D_PF_DROPPED         LOGLEV(4, 56, 0)        /* packet filter dropped a packet */
+#define D_MULTI_DROPPED      LOGLEV(4, 57, 0)        /* show point-to-multipoint packet drops */
+#define D_MULTI_MEDIUM       LOGLEV(4, 58, 0)        /* show medium frequency multi messages */
+#define D_X509_ATTR          LOGLEV(4, 59, 0)        /* show x509-track attributes on connection */
+#define D_INIT_MEDIUM        LOGLEV(4, 60, 0)        /* show medium frequency init messages */
+#define D_MTU_INFO           LOGLEV(4, 61, 0)        /* show terse MTU info */
+#define D_PID_DEBUG_LOW      LOGLEV(4, 63, 0)        /* show low-freq packet-id debugging info */
+#define D_PID_DEBUG_MEDIUM   LOGLEV(4, 64, 0)        /* show medium-freq packet-id debugging info */
+
+#define D_LOG_RW             LOGLEV(5, 0,  0)        /* Print 'R' or 'W' to stdout for read/write */
+
+#define D_LINK_RW            LOGLEV(6, 69, M_DEBUG)  /* show TCP/UDP reads/writes (terse) */
+#define D_TUN_RW             LOGLEV(6, 69, M_DEBUG)  /* show TUN/TAP reads/writes */
+#define D_TAP_WIN_DEBUG      LOGLEV(6, 69, M_DEBUG)  /* show TAP-Windows driver debug info */
+#define D_CLIENT_NAT         LOGLEV(6, 69, M_DEBUG)  /* show client NAT debug info */
+
+#define D_SHOW_KEYS          LOGLEV(7, 70, M_DEBUG)  /* show data channel encryption keys */
+#define D_SHOW_KEY_SOURCE    LOGLEV(7, 70, M_DEBUG)  /* show data channel key source entropy */
+#define D_REL_LOW            LOGLEV(7, 70, M_DEBUG)  /* show low frequency info from reliable layer */
+#define D_FRAG_DEBUG         LOGLEV(7, 70, M_DEBUG)  /* show fragment debugging info */
+#define D_WIN32_IO_LOW       LOGLEV(7, 70, M_DEBUG)  /* low freq win32 I/O debugging info */
+#define D_MTU_DEBUG          LOGLEV(7, 70, M_DEBUG)  /* show MTU debugging info */
+#define D_MULTI_DEBUG        LOGLEV(7, 70, M_DEBUG)  /* show medium-freq multi debugging info */
+#define D_MSS                LOGLEV(7, 70, M_DEBUG)  /* show MSS adjustments */
+#define D_COMP_LOW           LOGLEV(7, 70, M_DEBUG)  /* show adaptive compression state changes */
+#define D_CONNECTION_LIST    LOGLEV(7, 70, M_DEBUG)  /* show <connection> list info */
+#define D_SCRIPT             LOGLEV(7, 70, M_DEBUG)  /* show parms & env vars passed to scripts */
+#define D_SHOW_NET           LOGLEV(7, 70, M_DEBUG)  /* show routing table and adapter list */
+#define D_ROUTE_DEBUG        LOGLEV(7, 70, M_DEBUG)  /* show verbose route.[ch] output */
+#define D_TLS_STATE_ERRORS   LOGLEV(7, 70, M_DEBUG)  /* no TLS state for client */
+#define D_SEMAPHORE_LOW      LOGLEV(7, 70, M_DEBUG)  /* show Win32 semaphore waits (low freq) */
+#define D_SEMAPHORE          LOGLEV(7, 70, M_DEBUG)  /* show Win32 semaphore waits */
+#define D_TEST_FILE          LOGLEV(7, 70, M_DEBUG)  /* show test_file() calls */
+#define D_MANAGEMENT_DEBUG   LOGLEV(3, 70, M_DEBUG)  /* show --management debug info */
+#define D_PLUGIN_DEBUG       LOGLEV(7, 70, M_DEBUG)  /* show verbose plugin calls */
+#define D_SOCKET_DEBUG       LOGLEV(7, 70, M_DEBUG)  /* show socket.[ch] debugging info */
+#define D_SHOW_PKCS11        LOGLEV(7, 70, M_DEBUG)  /* show PKCS#11 actions */
+#define D_ALIGN_DEBUG        LOGLEV(7, 70, M_DEBUG)  /* show verbose struct alignment info */
+#define D_PACKET_TRUNC_DEBUG LOGLEV(7, 70, M_DEBUG)  /* PACKET_TRUNCATION_CHECK verbose */
+#define D_PING               LOGLEV(7, 70, M_DEBUG)  /* PING send/receive messages */
+#define D_PS_PROXY_DEBUG     LOGLEV(7, 70, M_DEBUG)  /* port share proxy debug */
+#define D_AUTO_USERID        LOGLEV(7, 70, M_DEBUG)  /* AUTO_USERID debugging */
+#define D_TLS_KEYSELECT      LOGLEV(7, 70, M_DEBUG)  /* show information on key selection for data channel */
+#define D_ARGV_PARSE_CMD     LOGLEV(7, 70, M_DEBUG)  /* show parse_line() errors in argv_parse_cmd */
+#define D_CRYPTO_DEBUG       LOGLEV(7, 70, M_DEBUG)  /* show detailed info from crypto.c routines */
+#define D_PID_DEBUG          LOGLEV(7, 70, M_DEBUG)  /* show packet-id debugging info */
+#define D_PF_DROPPED_BCAST   LOGLEV(7, 71, M_DEBUG)  /* packet filter dropped a broadcast packet */
+#define D_PF_DEBUG           LOGLEV(7, 72, M_DEBUG)  /* packet filter debugging, must also define PF_DEBUG in pf.h */
+#define D_PUSH_DEBUG         LOGLEV(7, 73, M_DEBUG)  /* show push/pull debugging info */
+
+#define D_HANDSHAKE_VERBOSE  LOGLEV(8, 70, M_DEBUG)  /* show detailed description of each handshake */
+#define D_TLS_DEBUG_MED      LOGLEV(8, 70, M_DEBUG)  /* limited info from tls_session routines */
+#define D_INTERVAL           LOGLEV(8, 70, M_DEBUG)  /* show interval.h debugging info */
+#define D_SCHEDULER          LOGLEV(8, 70, M_DEBUG)  /* show scheduler debugging info */
+#define D_GREMLIN_VERBOSE    LOGLEV(8, 70, M_DEBUG)  /* show verbose info from gremlin module */
+#define D_REL_DEBUG          LOGLEV(8, 70, M_DEBUG)  /* show detailed info from reliable routines */
+#define D_EVENT_WAIT         LOGLEV(8, 70, M_DEBUG)  /* show detailed info from event waits */
+#define D_MULTI_TCP          LOGLEV(8, 70, M_DEBUG)  /* show debug info from mtcp.c */
+
+#define D_TLS_DEBUG          LOGLEV(9, 70, M_DEBUG)  /* show detailed info from TLS routines */
+#define D_COMP               LOGLEV(9, 70, M_DEBUG)  /* show compression info */
+#define D_READ_WRITE         LOGLEV(9, 70, M_DEBUG)  /* show all tun/tcp/udp reads/writes/opens */
+#define D_PACKET_CONTENT     LOGLEV(9, 70, M_DEBUG)  /* show before/after encryption packet content */
+#define D_TLS_NO_SEND_KEY    LOGLEV(9, 70, M_DEBUG)  /* show when no data channel send-key exists */
+#define D_PID_PERSIST_DEBUG  LOGLEV(9, 70, M_DEBUG)  /* show packet-id persist debugging info */
+#define D_LINK_RW_VERBOSE    LOGLEV(9, 70, M_DEBUG)  /* show link reads/writes with greater verbosity */
+#define D_STREAM_DEBUG       LOGLEV(9, 70, M_DEBUG)  /* show TCP stream debug info */
+#define D_WIN32_IO           LOGLEV(9, 70, M_DEBUG)  /* win32 I/O debugging info */
+#define D_PKCS11_DEBUG       LOGLEV(9, 70, M_DEBUG)  /* show PKCS#11 debugging */
+
+#define D_SHAPER_DEBUG       LOGLEV(10, 70, M_DEBUG) /* show traffic shaper info */
+
+#define D_REGISTRY           LOGLEV(11, 70, M_DEBUG) /* win32 registry debugging info */
+#define D_OPENSSL_LOCK       LOGLEV(11, 70, M_DEBUG) /* show OpenSSL locks */
+
+/*#define D_THREAD_DEBUG       LOGLEV(4, 70, M_DEBUG)*/  /* show pthread debug information */
+
+#endif /* ifndef ERRLEVEL_H */
diff --git a/src/openvpn/error.c b/src/openvpn/error.c
new file mode 100644
index 0000000..bc14e8c
--- /dev/null
+++ b/src/openvpn/error.c
@@ -0,0 +1,1018 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "error.h"
+#include "buffer.h"
+#include "misc.h"
+#include "win32.h"
+#include "socket.h"
+#include "tun.h"
+#include "otime.h"
+#include "perf.h"
+#include "status.h"
+#include "integer.h"
+#include "ps.h"
+#include "mstats.h"
+
+
+#if SYSLOG_CAPABILITY
+#ifndef LOG_OPENVPN
+#define LOG_OPENVPN LOG_DAEMON
+#endif
+#endif
+
+/* Globals */
+unsigned int x_debug_level; /* GLOBAL */
+
+/* Mute state */
+static int mute_cutoff;     /* GLOBAL */
+static int mute_count;      /* GLOBAL */
+static int mute_category;   /* GLOBAL */
+
+/*
+ * Output mode priorities are as follows:
+ *
+ *  (1) --log-x overrides everything
+ *  (2) syslog is used if --daemon or --inetd is defined and not --log-x
+ *  (3) if OPENVPN_DEBUG_COMMAND_LINE is defined, output
+ *      to constant logfile name.
+ *  (4) Output to stdout.
+ */
+
+/* If true, indicates that stdin/stdout/stderr
+ * have been redirected due to --log */
+static bool std_redir;      /* GLOBAL */
+
+/* Should messages be written to the syslog? */
+static bool use_syslog;     /* GLOBAL */
+
+/* Should stdout/stderr be be parsable and always be prefixed with time
+ * and message flags */
+static bool machine_readable_output;   /* GLOBAL */
+
+/* Should timestamps be included on messages to stdout/stderr? */
+static bool suppress_timestamps; /* GLOBAL */
+
+/* The program name passed to syslog */
+#if SYSLOG_CAPABILITY
+static char *pgmname_syslog;  /* GLOBAL */
+#endif
+
+/* If non-null, messages should be written here (used for debugging only) */
+static FILE *msgfp;         /* GLOBAL */
+
+/* If true, we forked from main OpenVPN process */
+static bool forked;         /* GLOBAL */
+
+/* our default output targets */
+static FILE *default_out; /* GLOBAL */
+static FILE *default_err; /* GLOBAL */
+
+void
+msg_forked(void)
+{
+    forked = true;
+}
+
+bool
+set_debug_level(const int level, const unsigned int flags)
+{
+    const int ceiling = 15;
+
+    if (level >= 0 && level <= ceiling)
+    {
+        x_debug_level = level;
+        return true;
+    }
+    else if (flags & SDL_CONSTRAIN)
+    {
+        x_debug_level = constrain_int(level, 0, ceiling);
+        return true;
+    }
+    return false;
+}
+
+bool
+set_mute_cutoff(const int cutoff)
+{
+    if (cutoff >= 0)
+    {
+        mute_cutoff = cutoff;
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+int
+get_debug_level(void)
+{
+    return x_debug_level;
+}
+
+int
+get_mute_cutoff(void)
+{
+    return mute_cutoff;
+}
+
+void
+set_suppress_timestamps(bool suppressed)
+{
+    suppress_timestamps = suppressed;
+}
+
+void
+set_machine_readable_output(bool parsable)
+{
+    machine_readable_output = parsable;
+}
+
+void
+error_reset(void)
+{
+    use_syslog = std_redir = false;
+    suppress_timestamps = false;
+    machine_readable_output = false;
+    x_debug_level = 1;
+    mute_cutoff = 0;
+    mute_count = 0;
+    mute_category = 0;
+    default_out = OPENVPN_MSG_FP;
+    default_err = OPENVPN_MSG_FP;
+
+#ifdef OPENVPN_DEBUG_COMMAND_LINE
+    msgfp = fopen(OPENVPN_DEBUG_FILE, "w");
+    if (!msgfp)
+    {
+        openvpn_exit(OPENVPN_EXIT_STATUS_CANNOT_OPEN_DEBUG_FILE); /* exit point */
+    }
+#else  /* ifdef OPENVPN_DEBUG_COMMAND_LINE */
+    msgfp = NULL;
+#endif
+}
+
+void
+errors_to_stderr(void)
+{
+    default_err = OPENVPN_ERROR_FP;
+}
+
+/*
+ * Return a file to print messages to before syslog is opened.
+ */
+FILE *
+msg_fp(const unsigned int flags)
+{
+    FILE *fp = msgfp;
+    if (!fp)
+    {
+        fp = (flags & (M_FATAL|M_USAGE_SMALL)) ? default_err : default_out;
+    }
+    if (!fp)
+    {
+        openvpn_exit(OPENVPN_EXIT_STATUS_CANNOT_OPEN_DEBUG_FILE); /* exit point */
+    }
+    return fp;
+}
+
+#define SWAP { tmp = m1; m1 = m2; m2 = tmp; }
+
+int x_msg_line_num; /* GLOBAL */
+
+void
+x_msg(const unsigned int flags, const char *format, ...)
+{
+    va_list arglist;
+    va_start(arglist, format);
+    x_msg_va(flags, format, arglist);
+    va_end(arglist);
+}
+
+void
+x_msg_va(const unsigned int flags, const char *format, va_list arglist)
+{
+    struct gc_arena gc;
+#if SYSLOG_CAPABILITY
+    int level;
+#endif
+    char *m1;
+    char *m2;
+    char *tmp;
+    int e;
+    const char *prefix;
+    const char *prefix_sep;
+
+    void usage_small(void);
+
+#ifndef HAVE_VARARG_MACROS
+    /* the macro has checked this otherwise */
+    if (!msg_test(flags))
+    {
+        return;
+    }
+#endif
+
+    e = openvpn_errno();
+
+    /*
+     * Apply muting filter.
+     */
+#ifndef HAVE_VARARG_MACROS
+    /* the macro has checked this otherwise */
+    if (!dont_mute(flags))
+    {
+        return;
+    }
+#endif
+
+    gc_init(&gc);
+
+    m1 = (char *) gc_malloc(ERR_BUF_SIZE, false, &gc);
+    m2 = (char *) gc_malloc(ERR_BUF_SIZE, false, &gc);
+
+    vsnprintf(m1, ERR_BUF_SIZE, format, arglist);
+    m1[ERR_BUF_SIZE - 1] = 0; /* windows vsnprintf needs this */
+
+    if ((flags & M_ERRNO) && e)
+    {
+        openvpn_snprintf(m2, ERR_BUF_SIZE, "%s: %s (errno=%d)",
+                         m1, strerror(e), e);
+        SWAP;
+    }
+
+    if (flags & M_OPTERR)
+    {
+        openvpn_snprintf(m2, ERR_BUF_SIZE, "Options error: %s", m1);
+        SWAP;
+    }
+
+#if SYSLOG_CAPABILITY
+    if (flags & (M_FATAL|M_NONFATAL|M_USAGE_SMALL))
+    {
+        level = LOG_ERR;
+    }
+    else if (flags & M_WARN)
+    {
+        level = LOG_WARNING;
+    }
+    else
+    {
+        level = LOG_NOTICE;
+    }
+#endif
+
+    /* set up client prefix */
+    if (flags & M_NOIPREFIX)
+    {
+        prefix = NULL;
+    }
+    else
+    {
+        prefix = msg_get_prefix();
+    }
+    prefix_sep = " ";
+    if (!prefix)
+    {
+        prefix_sep = prefix = "";
+    }
+
+    /* virtual output capability used to copy output to management subsystem */
+    if (!forked)
+    {
+        const struct virtual_output *vo = msg_get_virtual_output();
+        if (vo)
+        {
+            openvpn_snprintf(m2, ERR_BUF_SIZE, "%s%s%s",
+                             prefix,
+                             prefix_sep,
+                             m1);
+            virtual_output_print(vo, flags, m2);
+        }
+    }
+
+    if (!(flags & M_MSG_VIRT_OUT))
+    {
+        if (use_syslog && !std_redir && !forked)
+        {
+#if SYSLOG_CAPABILITY
+            syslog(level, "%s%s%s",
+                   prefix,
+                   prefix_sep,
+                   m1);
+#endif
+        }
+        else
+        {
+            FILE *fp = msg_fp(flags);
+            const bool show_usec = check_debug_level(DEBUG_LEVEL_USEC_TIME);
+
+            if (machine_readable_output)
+            {
+                struct timeval tv;
+                gettimeofday(&tv, NULL);
+
+                fprintf(fp, "%"PRIi64".%06lu %x %s%s%s%s",
+                        (int64_t)tv.tv_sec,
+                        (unsigned long)tv.tv_usec,
+                        flags,
+                        prefix,
+                        prefix_sep,
+                        m1,
+                        "\n");
+
+            }
+            else if ((flags & M_NOPREFIX) || suppress_timestamps)
+            {
+                fprintf(fp, "%s%s%s%s",
+                        prefix,
+                        prefix_sep,
+                        m1,
+                        (flags&M_NOLF) ? "" : "\n");
+            }
+            else
+            {
+                fprintf(fp, "%s %s%s%s%s",
+                        time_string(0, 0, show_usec, &gc),
+                        prefix,
+                        prefix_sep,
+                        m1,
+                        (flags&M_NOLF) ? "" : "\n");
+            }
+            fflush(fp);
+            ++x_msg_line_num;
+        }
+    }
+
+    if (flags & M_FATAL)
+    {
+        msg(M_INFO, "Exiting due to fatal error");
+    }
+
+    if (flags & M_FATAL)
+    {
+        openvpn_exit(OPENVPN_EXIT_STATUS_ERROR); /* exit point */
+
+    }
+    if (flags & M_USAGE_SMALL)
+    {
+        usage_small();
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Apply muting filter.
+ */
+bool
+dont_mute(unsigned int flags)
+{
+    bool ret = true;
+    if (mute_cutoff > 0 && !(flags & M_NOMUTE))
+    {
+        const int mute_level = DECODE_MUTE_LEVEL(flags);
+        if (mute_level > 0 && mute_level == mute_category)
+        {
+            if (mute_count == mute_cutoff)
+            {
+                msg(M_INFO | M_NOMUTE, "NOTE: --mute triggered...");
+            }
+            if (++mute_count > mute_cutoff)
+            {
+                ret = false;
+            }
+        }
+        else
+        {
+            const int suppressed = mute_count - mute_cutoff;
+            if (suppressed > 0)
+            {
+                msg(M_INFO | M_NOMUTE,
+                    "%d variation(s) on previous %d message(s) suppressed by --mute",
+                    suppressed,
+                    mute_cutoff);
+            }
+            mute_count = 1;
+            mute_category = mute_level;
+        }
+    }
+    return ret;
+}
+
+void
+assert_failed(const char *filename, int line, const char *condition)
+{
+    if (condition)
+    {
+        msg(M_FATAL, "Assertion failed at %s:%d (%s)", filename, line, condition);
+    }
+    else
+    {
+        msg(M_FATAL, "Assertion failed at %s:%d", filename, line);
+    }
+    _exit(1);
+}
+
+/*
+ * Fail memory allocation.  Don't use msg() because it tries
+ * to allocate memory as part of its operation.
+ */
+void
+out_of_memory(void)
+{
+    fprintf(stderr, PACKAGE_NAME ": Out of Memory\n");
+    exit(1);
+}
+
+void
+open_syslog(const char *pgmname, bool stdio_to_null)
+{
+#if SYSLOG_CAPABILITY
+    if (!msgfp && !std_redir)
+    {
+        if (!use_syslog)
+        {
+            pgmname_syslog = string_alloc(pgmname ? pgmname : PACKAGE, NULL);
+            openlog(pgmname_syslog, LOG_PID, LOG_OPENVPN);
+            use_syslog = true;
+
+            /* Better idea: somehow pipe stdout/stderr output to msg() */
+            if (stdio_to_null)
+            {
+                set_std_files_to_null(false);
+            }
+        }
+    }
+#else  /* if SYSLOG_CAPABILITY */
+    msg(M_WARN, "Warning on use of --daemon/--inetd: this operating system lacks daemon logging features, therefore when I become a daemon, I won't be able to log status or error messages");
+#endif
+}
+
+void
+close_syslog(void)
+{
+#if SYSLOG_CAPABILITY
+    if (use_syslog)
+    {
+        closelog();
+        use_syslog = false;
+        if (pgmname_syslog)
+        {
+            free(pgmname_syslog);
+            pgmname_syslog = NULL;
+        }
+    }
+#endif
+}
+
+#ifdef _WIN32
+
+static HANDLE orig_stderr;
+
+HANDLE
+get_orig_stderr(void)
+{
+    if (orig_stderr)
+    {
+        return orig_stderr;
+    }
+    else
+    {
+        return GetStdHandle(STD_ERROR_HANDLE);
+    }
+}
+
+#endif
+
+void
+redirect_stdout_stderr(const char *file, bool append)
+{
+#if defined(_WIN32)
+    if (!std_redir)
+    {
+        struct gc_arena gc = gc_new();
+        HANDLE log_handle;
+        int log_fd;
+
+        SECURITY_ATTRIBUTES saAttr;
+        saAttr.nLength = sizeof(SECURITY_ATTRIBUTES);
+        saAttr.bInheritHandle = TRUE;
+        saAttr.lpSecurityDescriptor = NULL;
+
+        log_handle = CreateFileW(wide_string(file, &gc),
+                                 GENERIC_WRITE,
+                                 FILE_SHARE_READ,
+                                 &saAttr,
+                                 append ? OPEN_ALWAYS : CREATE_ALWAYS,
+                                 FILE_ATTRIBUTE_NORMAL,
+                                 NULL);
+
+        gc_free(&gc);
+
+        if (log_handle == INVALID_HANDLE_VALUE)
+        {
+            msg(M_WARN|M_ERRNO, "Warning: cannot open --log file: %s", file);
+            return;
+        }
+
+        /* append to logfile? */
+        if (append)
+        {
+            if (SetFilePointer(log_handle, 0, NULL, FILE_END) == INVALID_SET_FILE_POINTER)
+            {
+                msg(M_ERR, "Error: cannot seek to end of --log file: %s", file);
+            }
+        }
+
+        /* save original stderr for password prompts */
+        orig_stderr = GetStdHandle(STD_ERROR_HANDLE);
+
+#if 0 /* seems not be necessary with stdout/stderr redirection below*/
+        /* set up for redirection */
+        if (!SetStdHandle(STD_OUTPUT_HANDLE, log_handle)
+            || !SetStdHandle(STD_ERROR_HANDLE, log_handle))
+        {
+            msg(M_ERR, "Error: cannot redirect stdout/stderr to --log file: %s", file);
+        }
+#endif
+
+        /* direct stdout/stderr to point to log_handle */
+        log_fd = _open_osfhandle((intptr_t)log_handle, _O_TEXT);
+        if (log_fd == -1)
+        {
+            msg(M_ERR, "Error: --log redirect failed due to _open_osfhandle failure");
+        }
+
+        /* open log_handle as FILE stream */
+        ASSERT(msgfp == NULL);
+        msgfp = _fdopen(log_fd, "wt");
+        if (msgfp == NULL)
+        {
+            msg(M_ERR, "Error: --log redirect failed due to _fdopen");
+        }
+
+        /* redirect C-library stdout/stderr to log file */
+        if (_dup2(log_fd, 1) == -1 || _dup2(log_fd, 2) == -1)
+        {
+            msg(M_WARN, "Error: --log redirect of stdout/stderr failed");
+        }
+
+        std_redir = true;
+    }
+#elif defined(HAVE_DUP2)
+    if (!std_redir)
+    {
+        int out = open(file,
+                       O_CREAT | O_WRONLY | (append ? O_APPEND : O_TRUNC),
+                       S_IRUSR | S_IWUSR);
+
+        if (out < 0)
+        {
+            msg(M_WARN|M_ERRNO, "Warning: Error redirecting stdout/stderr to --log file: %s", file);
+            return;
+        }
+
+        if (dup2(out, 1) == -1)
+        {
+            msg(M_ERR, "--log file redirection error on stdout");
+        }
+        if (dup2(out, 2) == -1)
+        {
+            msg(M_ERR, "--log file redirection error on stderr");
+        }
+
+        if (out > 2)
+        {
+            close(out);
+        }
+
+        std_redir = true;
+    }
+
+#else  /* if defined(_WIN32) */
+    msg(M_WARN, "WARNING: The --log option is not supported on this OS because it lacks the dup2 function");
+#endif /* if defined(_WIN32) */
+}
+
+/*
+ * Functions used to check return status
+ * of I/O operations.
+ */
+
+unsigned int x_cs_info_level;    /* GLOBAL */
+unsigned int x_cs_verbose_level; /* GLOBAL */
+unsigned int x_cs_err_delay_ms;  /* GLOBAL */
+
+void
+reset_check_status(void)
+{
+    x_cs_info_level = 0;
+    x_cs_verbose_level = 0;
+}
+
+void
+set_check_status(unsigned int info_level, unsigned int verbose_level)
+{
+    x_cs_info_level = info_level;
+    x_cs_verbose_level = verbose_level;
+}
+
+/*
+ * Called after most socket or tun/tap operations, via the inline
+ * function check_status().
+ *
+ * Decide if we should print an error message, and see if we can
+ * extract any useful info from the error, such as a Path MTU hint
+ * from the OS.
+ */
+void
+x_check_status(int status,
+               const char *description,
+               struct link_socket *sock,
+               struct tuntap *tt)
+{
+    const int my_errno = openvpn_errno();
+    const char *extended_msg = NULL;
+
+    msg(x_cs_verbose_level, "%s %s returned %d",
+        sock ? proto2ascii(sock->info.proto, sock->info.af, true) : "",
+        description,
+        status);
+
+    if (status < 0)
+    {
+        struct gc_arena gc = gc_new();
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+        /* get extended socket error message and possible PMTU hint from OS */
+        if (sock)
+        {
+            int mtu;
+            extended_msg = format_extended_socket_error(sock->sd, &mtu, &gc);
+            if (mtu > 0 && sock->mtu != mtu)
+            {
+                sock->mtu = mtu;
+                sock->info.mtu_changed = true;
+            }
+        }
+#elif defined(_WIN32)
+        /* get possible driver error from TAP-Windows driver */
+        extended_msg = tap_win_getinfo(tt, &gc);
+#endif
+        if (!ignore_sys_error(my_errno))
+        {
+            if (extended_msg)
+            {
+                msg(x_cs_info_level, "%s %s [%s]: %s (code=%d)", description,
+                    sock ? proto2ascii(sock->info.proto, sock->info.af, true) : "",
+                    extended_msg, strerror(my_errno), my_errno);
+            }
+            else
+            {
+                msg(x_cs_info_level, "%s %s: %s (code=%d)", description,
+                    sock ? proto2ascii(sock->info.proto, sock->info.af, true) : "",
+                    strerror(my_errno), my_errno);
+            }
+
+            if (x_cs_err_delay_ms)
+            {
+                platform_sleep_milliseconds(x_cs_err_delay_ms);
+            }
+        }
+        gc_free(&gc);
+    }
+}
+
+/*
+ * In multiclient mode, put a client-specific prefix
+ * before each message.
+ */
+const char *x_msg_prefix; /* GLOBAL */
+
+/*
+ * Allow MSG to be redirected through a virtual_output object
+ */
+
+const struct virtual_output *x_msg_virtual_output; /* GLOBAL */
+
+/*
+ * Exiting.
+ */
+
+void
+openvpn_exit(const int status)
+{
+    if (!forked)
+    {
+        void tun_abort();
+
+#ifdef ENABLE_PLUGIN
+        void plugin_abort(void);
+
+#endif
+
+        tun_abort();
+
+#ifdef _WIN32
+        uninit_win32();
+#endif
+
+        close_syslog();
+
+#ifdef ENABLE_PLUGIN
+        plugin_abort();
+#endif
+
+#if PORT_SHARE
+        if (port_share)
+        {
+            port_share_abort(port_share);
+        }
+#endif
+
+#ifdef ENABLE_MEMSTATS
+        mstats_close();
+#endif
+
+#ifdef ABORT_ON_ERROR
+        if (status == OPENVPN_EXIT_STATUS_ERROR)
+        {
+            abort();
+        }
+#endif
+
+        if (status == OPENVPN_EXIT_STATUS_GOOD)
+        {
+            perf_output_results();
+        }
+    }
+
+    exit(status);
+}
+
+/*
+ * Translate msg flags into a string
+ */
+const char *
+msg_flags_string(const unsigned int flags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(16, gc);
+    if (flags == M_INFO)
+    {
+        buf_printf(&out, "I");
+    }
+    if (flags & M_FATAL)
+    {
+        buf_printf(&out, "F");
+    }
+    if (flags & M_NONFATAL)
+    {
+        buf_printf(&out, "N");
+    }
+    if (flags & M_WARN)
+    {
+        buf_printf(&out, "W");
+    }
+    if (flags & M_DEBUG)
+    {
+        buf_printf(&out, "D");
+    }
+    return BSTR(&out);
+}
+
+#ifdef ENABLE_DEBUG
+void
+crash(void)
+{
+    char *null = NULL;
+    *null = 0;
+}
+#endif
+
+#ifdef _WIN32
+
+const char *
+strerror_win32(DWORD errnum, struct gc_arena *gc)
+{
+    /*
+     * This code can be omitted, though often the Windows
+     * WSA error messages are less informative than the
+     * Posix equivalents.
+     */
+#if 1
+    switch (errnum)
+    {
+        /*
+         * When the TAP-Windows driver returns STATUS_UNSUCCESSFUL, this code
+         * gets returned to user space.
+         */
+        case ERROR_GEN_FAILURE:
+            return "General failure (ERROR_GEN_FAILURE)";
+
+        case ERROR_IO_PENDING:
+            return "I/O Operation in progress (ERROR_IO_PENDING)";
+
+        case WSA_IO_INCOMPLETE:
+            return "I/O Operation in progress (WSA_IO_INCOMPLETE)";
+
+        case WSAEINTR:
+            return "Interrupted system call (WSAEINTR)";
+
+        case WSAEBADF:
+            return "Bad file number (WSAEBADF)";
+
+        case WSAEACCES:
+            return "Permission denied (WSAEACCES)";
+
+        case WSAEFAULT:
+            return "Bad address (WSAEFAULT)";
+
+        case WSAEINVAL:
+            return "Invalid argument (WSAEINVAL)";
+
+        case WSAEMFILE:
+            return "Too many open files (WSAEMFILE)";
+
+        case WSAEWOULDBLOCK:
+            return "Operation would block (WSAEWOULDBLOCK)";
+
+        case WSAEINPROGRESS:
+            return "Operation now in progress (WSAEINPROGRESS)";
+
+        case WSAEALREADY:
+            return "Operation already in progress (WSAEALREADY)";
+
+        case WSAEDESTADDRREQ:
+            return "Destination address required (WSAEDESTADDRREQ)";
+
+        case WSAEMSGSIZE:
+            return "Message too long (WSAEMSGSIZE)";
+
+        case WSAEPROTOTYPE:
+            return "Protocol wrong type for socket (WSAEPROTOTYPE)";
+
+        case WSAENOPROTOOPT:
+            return "Bad protocol option (WSAENOPROTOOPT)";
+
+        case WSAEPROTONOSUPPORT:
+            return "Protocol not supported (WSAEPROTONOSUPPORT)";
+
+        case WSAESOCKTNOSUPPORT:
+            return "Socket type not supported (WSAESOCKTNOSUPPORT)";
+
+        case WSAEOPNOTSUPP:
+            return "Operation not supported on socket (WSAEOPNOTSUPP)";
+
+        case WSAEPFNOSUPPORT:
+            return "Protocol family not supported (WSAEPFNOSUPPORT)";
+
+        case WSAEAFNOSUPPORT:
+            return "Address family not supported by protocol family (WSAEAFNOSUPPORT)";
+
+        case WSAEADDRINUSE:
+            return "Address already in use (WSAEADDRINUSE)";
+
+        case WSAENETDOWN:
+            return "Network is down (WSAENETDOWN)";
+
+        case WSAENETUNREACH:
+            return "Network is unreachable (WSAENETUNREACH)";
+
+        case WSAENETRESET:
+            return "Net dropped connection or reset (WSAENETRESET)";
+
+        case WSAECONNABORTED:
+            return "Software caused connection abort (WSAECONNABORTED)";
+
+        case WSAECONNRESET:
+            return "Connection reset by peer (WSAECONNRESET)";
+
+        case WSAENOBUFS:
+            return "No buffer space available (WSAENOBUFS)";
+
+        case WSAEISCONN:
+            return "Socket is already connected (WSAEISCONN)";
+
+        case WSAENOTCONN:
+            return "Socket is not connected (WSAENOTCONN)";
+
+        case WSAETIMEDOUT:
+            return "Connection timed out (WSAETIMEDOUT)";
+
+        case WSAECONNREFUSED:
+            return "Connection refused (WSAECONNREFUSED)";
+
+        case WSAELOOP:
+            return "Too many levels of symbolic links (WSAELOOP)";
+
+        case WSAENAMETOOLONG:
+            return "File name too long (WSAENAMETOOLONG)";
+
+        case WSAEHOSTDOWN:
+            return "Host is down (WSAEHOSTDOWN)";
+
+        case WSAEHOSTUNREACH:
+            return "No Route to Host (WSAEHOSTUNREACH)";
+
+        case WSAENOTEMPTY:
+            return "Directory not empty (WSAENOTEMPTY)";
+
+        case WSAEPROCLIM:
+            return "Too many processes (WSAEPROCLIM)";
+
+        case WSAEUSERS:
+            return "Too many users (WSAEUSERS)";
+
+        case WSAEDQUOT:
+            return "Disc Quota Exceeded (WSAEDQUOT)";
+
+        case WSAESTALE:
+            return "Stale NFS file handle (WSAESTALE)";
+
+        case WSASYSNOTREADY:
+            return "Network SubSystem is unavailable (WSASYSNOTREADY)";
+
+        case WSAVERNOTSUPPORTED:
+            return "WINSOCK DLL Version out of range (WSAVERNOTSUPPORTED)";
+
+        case WSANOTINITIALISED:
+            return "Successful WSASTARTUP not yet performed (WSANOTINITIALISED)";
+
+        case WSAEREMOTE:
+            return "Too many levels of remote in path (WSAEREMOTE)";
+
+        case WSAHOST_NOT_FOUND:
+            return "Host not found (WSAHOST_NOT_FOUND)";
+
+        default:
+            break;
+    }
+#endif /* if 1 */
+
+    /* format a windows error message */
+    {
+        char message[256];
+        struct buffer out = alloc_buf_gc(256, gc);
+        const int status =  FormatMessage(
+            FORMAT_MESSAGE_IGNORE_INSERTS
+            | FORMAT_MESSAGE_FROM_SYSTEM
+            | FORMAT_MESSAGE_ARGUMENT_ARRAY,
+            NULL,
+            errnum,
+            0,
+            message,
+            sizeof(message),
+            NULL);
+        if (!status)
+        {
+            buf_printf(&out, "[Unknown Win32 Error]");
+        }
+        else
+        {
+            char *cp;
+            for (cp = message; *cp != '\0'; ++cp)
+            {
+                if (*cp == '\n' || *cp == '\r')
+                {
+                    *cp = ' ';
+                }
+            }
+
+            buf_printf(&out, "%s", message);
+        }
+
+        return BSTR(&out);
+    }
+}
+
+#endif /* ifdef _WIN32 */
diff --git a/src/openvpn/error.h b/src/openvpn/error.h
new file mode 100644
index 0000000..eaedf17
--- /dev/null
+++ b/src/openvpn/error.h
@@ -0,0 +1,403 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef ERROR_H
+#define ERROR_H
+
+#include "basic.h"
+
+#include <errno.h>
+#include <stdbool.h>
+
+#include <assert.h>
+
+/* #define ABORT_ON_ERROR */
+
+#ifdef ENABLE_PKCS11
+#define ERR_BUF_SIZE 8192
+#else
+#define ERR_BUF_SIZE 1280
+#endif
+
+struct gc_arena;
+
+/*
+ * Where should messages be printed before syslog is opened?
+ * Not used if OPENVPN_DEBUG_COMMAND_LINE is defined.
+ */
+#define OPENVPN_MSG_FP   stdout
+#define OPENVPN_ERROR_FP stderr
+
+/*
+ * Exit status codes
+ */
+
+#define OPENVPN_EXIT_STATUS_GOOD                    0
+#define OPENVPN_EXIT_STATUS_ERROR                   1
+#define OPENVPN_EXIT_STATUS_USAGE                   1
+#define OPENVPN_EXIT_STATUS_CANNOT_OPEN_DEBUG_FILE  1
+
+/*
+ * Special command line debugging mode.
+ * If OPENVPN_DEBUG_COMMAND_LINE
+ * is defined, contents of argc/argv will
+ * be dumped to OPENVPN_DEBUG_FILE as well
+ * as all other OpenVPN messages.
+ */
+
+/* #define OPENVPN_DEBUG_COMMAND_LINE */
+#define OPENVPN_DEBUG_FILE PACKAGE ".log"
+
+/* String and Error functions */
+
+#ifdef _WIN32
+#define openvpn_errno()             GetLastError()
+#define openvpn_strerror(e, gc)     strerror_win32(e, gc)
+const char *strerror_win32(DWORD errnum, struct gc_arena *gc);
+
+#else
+#define openvpn_errno()             errno
+#define openvpn_strerror(x, gc)     strerror(x)
+#endif
+
+/*
+ * These globals should not be accessed directly,
+ * but rather through macros or inline functions defined below.
+ */
+extern unsigned int x_debug_level;
+extern int x_msg_line_num;
+
+/* msg() flags */
+
+#define M_DEBUG_LEVEL     (0x0F)         /* debug level mask */
+
+#define M_FATAL           (1<<4)         /* exit program */
+#define M_NONFATAL        (1<<5)         /* non-fatal error */
+#define M_WARN            (1<<6)         /* call syslog with LOG_WARNING */
+#define M_DEBUG           (1<<7)
+
+#define M_ERRNO           (1<<8)         /* show errno description */
+
+#define M_NOMUTE          (1<<11)        /* don't do mute processing */
+#define M_NOPREFIX        (1<<12)        /* don't show date/time prefix */
+#define M_USAGE_SMALL     (1<<13)        /* fatal options error, call usage_small */
+#define M_MSG_VIRT_OUT    (1<<14)        /* output message through msg_status_output callback */
+#define M_OPTERR          (1<<15)        /* print "Options error:" prefix */
+#define M_NOLF            (1<<16)        /* don't print new line */
+#define M_NOIPREFIX       (1<<17)        /* don't print instance prefix */
+
+/* flag combinations which are frequently used */
+#define M_ERR     (M_FATAL | M_ERRNO)
+#define M_USAGE   (M_USAGE_SMALL | M_NOPREFIX | M_OPTERR)
+#define M_CLIENT  (M_MSG_VIRT_OUT | M_NOMUTE | M_NOIPREFIX)
+
+/*
+ * Mute levels are designed to avoid large numbers of
+ * mostly similar messages clogging the log file.
+ *
+ * A mute level of 0 is always printed.
+ */
+#define MUTE_LEVEL_SHIFT 24
+#define MUTE_LEVEL_MASK 0xFF
+
+#define ENCODE_MUTE_LEVEL(mute_level) (((mute_level) & MUTE_LEVEL_MASK) << MUTE_LEVEL_SHIFT)
+#define DECODE_MUTE_LEVEL(flags) (((flags) >> MUTE_LEVEL_SHIFT) & MUTE_LEVEL_MASK)
+
+/*
+ * log_level:  verbosity level n (--verb n) must be >= log_level to print.
+ * mute_level: don't print more than n (--mute n) consecutive messages at
+ *             a given mute level, or if 0 disable muting and print everything.
+ *
+ * Mask map:
+ * Bits 0-3:   log level
+ * Bits 4-23:  M_x flags
+ * Bits 24-31: mute level
+ */
+#define LOGLEV(log_level, mute_level, other) ((log_level) | ENCODE_MUTE_LEVEL(mute_level) | other)
+
+/*
+ * If compiler supports variable arguments in macros, define
+ * msg() as a macro for optimization win.
+ */
+
+/** Check muting filter */
+bool dont_mute(unsigned int flags);
+
+/* Macro to ensure (and teach static analysis tools) we exit on fatal errors */
+#define EXIT_FATAL(flags) do { if ((flags) & M_FATAL) {_exit(1);}} while (false)
+
+#if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__)
+#define HAVE_VARARG_MACROS
+#define msg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)
+#ifdef ENABLE_DEBUG
+#define dmsg(flags, ...) do { if (msg_test(flags)) {x_msg((flags), __VA_ARGS__);} EXIT_FATAL(flags); } while (false)
+#else
+#define dmsg(flags, ...)
+#endif
+#elif defined(HAVE_CPP_VARARG_MACRO_GCC) && !defined(__LCLINT__)
+#define HAVE_VARARG_MACROS
+#define msg(flags, args ...) do { if (msg_test(flags)) {x_msg((flags), args);} EXIT_FATAL(flags); } while (false)
+#ifdef ENABLE_DEBUG
+#define dmsg(flags, args ...) do { if (msg_test(flags)) {x_msg((flags), args);} EXIT_FATAL(flags); } while (false)
+#else
+#define dmsg(flags, args ...)
+#endif
+#else  /* if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__) */
+#if !PEDANTIC
+#ifdef _MSC_VER
+#pragma message("this compiler appears to lack vararg macros which will cause a significant degradation in efficiency")
+#else
+#warning this compiler appears to lack vararg macros which will cause a significant degradation in efficiency (you can ignore this warning if you are using LCLINT)
+#endif
+#endif
+#define msg x_msg
+#define dmsg x_msg
+#endif /* if defined(HAVE_CPP_VARARG_MACRO_ISO) && !defined(__LCLINT__) */
+
+void x_msg(const unsigned int flags, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 2, 3)))
+#else
+__attribute__ ((format(__printf__, 2, 3)))
+#endif
+#endif
+;     /* should be called via msg above */
+
+void x_msg_va(const unsigned int flags, const char *format, va_list arglist);
+
+/*
+ * Function prototypes
+ */
+
+void error_reset(void);
+
+/* route errors to stderr that would normally go to stdout */
+void errors_to_stderr(void);
+
+void set_suppress_timestamps(bool suppressed);
+
+void set_machine_readable_output(bool parsable);
+
+
+#define SDL_CONSTRAIN (1<<0)
+bool set_debug_level(const int level, const unsigned int flags);
+
+bool set_mute_cutoff(const int cutoff);
+
+int get_debug_level(void);
+
+int get_mute_cutoff(void);
+
+const char *msg_flags_string(const unsigned int flags, struct gc_arena *gc);
+
+/*
+ * File to print messages to before syslog is opened.
+ */
+FILE *msg_fp(const unsigned int flags);
+
+/* Fatal logic errors */
+#ifndef ENABLE_SMALL
+#define ASSERT(x) do { if (!(x)) {assert_failed(__FILE__, __LINE__, #x);}} while (false)
+#else
+#define ASSERT(x) do { if (!(x)) {assert_failed(__FILE__, __LINE__, NULL);}} while (false)
+#endif
+
+void assert_failed(const char *filename, int line, const char *condition)
+__attribute__((__noreturn__));
+
+/* Poor-man's static_assert() for when not supplied by assert.h, taken from
+ * Linux's sys/cdefs.h under GPLv2 */
+#ifndef static_assert
+#define static_assert(expr, diagnostic) \
+    extern int (*__OpenVPN_static_assert_function(void)) \
+    [!!sizeof(struct { int __error_if_negative : (expr) ? 2 : -1; })]
+#endif
+
+#ifdef ENABLE_DEBUG
+void crash(void);  /* force a segfault (debugging only) */
+
+#endif
+
+/* Inline functions */
+
+static inline bool
+check_debug_level(unsigned int level)
+{
+    return (level & M_DEBUG_LEVEL) <= x_debug_level;
+}
+
+/** Return true if flags represent an enabled, not muted log level */
+static inline bool
+msg_test(unsigned int flags)
+{
+    return check_debug_level(flags) && dont_mute(flags);
+}
+
+/* Call if we forked */
+void msg_forked(void);
+
+/* syslog output */
+
+void open_syslog(const char *pgmname, bool stdio_to_null);
+
+void close_syslog(void);
+
+/* log file output */
+void redirect_stdout_stderr(const char *file, bool append);
+
+#ifdef _WIN32
+/* get original stderr handle, even if redirected by --log/--log-append */
+HANDLE get_orig_stderr(void);
+
+#endif
+
+/* exit program */
+void openvpn_exit(const int status);
+
+/* exit program on out of memory error */
+void out_of_memory(void);
+
+/*
+ * Check the return status of read/write routines.
+ */
+
+struct link_socket;
+struct tuntap;
+
+extern unsigned int x_cs_info_level;
+extern unsigned int x_cs_verbose_level;
+extern unsigned int x_cs_err_delay_ms;
+
+void reset_check_status(void);
+
+void set_check_status(unsigned int info_level, unsigned int verbose_level);
+
+void x_check_status(int status,
+                    const char *description,
+                    struct link_socket *sock,
+                    struct tuntap *tt);
+
+static inline void
+check_status(int status, const char *description, struct link_socket *sock, struct tuntap *tt)
+{
+    if (status < 0 || check_debug_level(x_cs_verbose_level))
+    {
+        x_check_status(status, description, sock, tt);
+    }
+}
+
+static inline void
+set_check_status_error_delay(unsigned int milliseconds)
+{
+    x_cs_err_delay_ms = milliseconds;
+}
+
+/*
+ * In multiclient mode, put a client-specific prefix
+ * before each message.
+ *
+ * TODO: x_msg_prefix should be thread-local
+ */
+
+extern const char *x_msg_prefix;
+
+void msg_thread_init(void);
+
+void msg_thread_uninit(void);
+
+static inline void
+msg_set_prefix(const char *prefix)
+{
+    x_msg_prefix = prefix;
+}
+
+static inline const char *
+msg_get_prefix(void)
+{
+    return x_msg_prefix;
+}
+
+/*
+ * Allow MSG to be redirected through a virtual_output object
+ */
+
+struct virtual_output;
+
+extern const struct virtual_output *x_msg_virtual_output;
+
+static inline void
+msg_set_virtual_output(const struct virtual_output *vo)
+{
+    x_msg_virtual_output = vo;
+}
+
+static inline const struct virtual_output *
+msg_get_virtual_output(void)
+{
+    return x_msg_virtual_output;
+}
+
+/*
+ * Return true if this is a system error
+ * which can be safely ignored.
+ */
+static inline bool
+ignore_sys_error(const int err)
+{
+    /* I/O operation pending */
+#ifdef _WIN32
+    if (err == WSAEWOULDBLOCK || err == WSAEINVAL)
+    {
+        return true;
+    }
+#else
+    if (err == EAGAIN)
+    {
+        return true;
+    }
+#endif
+
+#if 0 /* if enabled, suppress ENOBUFS errors */
+#ifdef ENOBUFS
+    /* No buffer space available */
+    if (err == ENOBUFS)
+    {
+        return true;
+    }
+#endif
+#endif
+
+    return false;
+}
+
+/** Convert fatal errors to nonfatal, don't touch other errors */
+static inline unsigned int
+nonfatal(const unsigned int err)
+{
+    return err & M_FATAL ? (err ^ M_FATAL) | M_NONFATAL : err;
+}
+
+#include "errlevel.h"
+
+#endif /* ifndef ERROR_H */
diff --git a/src/openvpn/event.c b/src/openvpn/event.c
new file mode 100644
index 0000000..b22741f
--- /dev/null
+++ b/src/openvpn/event.c
@@ -0,0 +1,1190 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "integer.h"
+#include "event.h"
+#include "fdmisc.h"
+
+#include "memdbg.h"
+
+/*
+ * Some OSes will prefer select() over poll()
+ * when both are available.
+ */
+#if defined(TARGET_DARWIN)
+#define SELECT_PREFERRED_OVER_POLL
+#endif
+
+/*
+ * All non-windows OSes are assumed to have select()
+ */
+#ifdef _WIN32
+#define SELECT 0
+#else
+#define SELECT 1
+#endif
+
+/*
+ * This should be set to the highest file descriptor
+ * which can be used in one of the FD_ macros.
+ */
+#ifdef FD_SETSIZE
+#define SELECT_MAX_FDS FD_SETSIZE
+#else
+#define SELECT_MAX_FDS 256
+#endif
+
+static inline int
+tv_to_ms_timeout(const struct timeval *tv)
+{
+    if (tv->tv_sec == 0 && tv->tv_usec == 0)
+    {
+        return 0;
+    }
+    else
+    {
+        return max_int(tv->tv_sec * 1000 + (tv->tv_usec + 500) / 1000, 1);
+    }
+}
+
+#ifdef _WIN32
+
+struct we_set
+{
+    struct event_set_functions func;
+    bool fast;
+    HANDLE *events;
+    struct event_set_return *esr;
+    int n_events;
+    int capacity;
+};
+
+static inline void
+we_set_event(struct we_set *wes, int i, event_t event, unsigned int rwflags, void *arg)
+{
+    ASSERT(i >= 0 && i < wes->capacity);
+
+    if (rwflags == EVENT_READ)
+    {
+        ASSERT(event->read != NULL);
+        wes->events[i] = event->read;
+    }
+    else if (rwflags == EVENT_WRITE)
+    {
+        ASSERT(event->write != NULL);
+        wes->events[i] = event->write;
+    }
+    else
+    {
+        msg(M_FATAL, "fatal error in we_set_events: rwflags=%d", rwflags);
+    }
+
+    wes->esr[i].rwflags = rwflags;
+    wes->esr[i].arg = arg;
+}
+
+static inline bool
+we_append_event(struct we_set *wes, event_t event, unsigned int rwflags, void *arg)
+{
+    if (rwflags & EVENT_WRITE)
+    {
+        if (wes->n_events < wes->capacity)
+        {
+            we_set_event(wes, wes->n_events, event, EVENT_WRITE, arg);
+            ++wes->n_events;
+        }
+        else
+        {
+            return false;
+        }
+    }
+    if (rwflags & EVENT_READ)
+    {
+        if (wes->n_events < wes->capacity)
+        {
+            we_set_event(wes, wes->n_events, event, EVENT_READ, arg);
+            ++wes->n_events;
+        }
+        else
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+static void
+we_del_event(struct we_set *wes, event_t event)
+{
+    int i, j = 0;
+    const int len = wes->n_events;
+
+    for (i = 0; i < len; ++i)
+    {
+        const HANDLE h = wes->events[i];
+        if (h == event->read || h == event->write)
+        {
+            --wes->n_events;
+        }
+        else
+        {
+            if (i != j)
+            {
+                wes->events[j] = wes->events[i];
+                wes->esr[j] = wes->esr[i];
+            }
+            ++j;
+        }
+    }
+}
+
+static void
+we_del_index(struct we_set *wes, int index)
+{
+    int i;
+    ASSERT(index >= 0 && index < wes->n_events);
+    for (i = index; i < wes->n_events - 1; ++i)
+    {
+        wes->events[i] = wes->events[i+1];
+        wes->esr[i] = wes->esr[i+1];
+    }
+    --wes->n_events;
+}
+
+static void
+we_get_rw_indices(struct we_set *wes, event_t event, int *ri, int *wi)
+{
+    int i;
+    *ri = *wi = -1;
+    for (i = 0; i < wes->n_events; ++i)
+    {
+        const HANDLE h = wes->events[i];
+        if (h == event->read)
+        {
+            ASSERT(*ri == -1);
+            *ri = i;
+        }
+        else if (h == event->write)
+        {
+            ASSERT(*wi == -1);
+            *wi = i;
+        }
+    }
+}
+
+static void
+we_free(struct event_set *es)
+{
+    struct we_set *wes = (struct we_set *) es;
+    free(wes->events);
+    free(wes->esr);
+    free(wes);
+}
+
+static void
+we_reset(struct event_set *es)
+{
+    struct we_set *wes = (struct we_set *) es;
+    ASSERT(wes->fast);
+    wes->n_events = 0;
+}
+
+static void
+we_del(struct event_set *es, event_t event)
+{
+    struct we_set *wes = (struct we_set *) es;
+    ASSERT(!wes->fast);
+    we_del_event(wes, event);
+}
+
+static void
+we_ctl(struct event_set *es, event_t event, unsigned int rwflags, void *arg)
+{
+    struct we_set *wes = (struct we_set *) es;
+
+    dmsg(D_EVENT_WAIT, "WE_CTL n=%d ev=%p rwflags=0x%04x arg=" ptr_format,
+         wes->n_events,
+         event,
+         rwflags,
+         (ptr_type)arg);
+
+    if (wes->fast)
+    {
+        if (!we_append_event(wes, event, rwflags, arg))
+        {
+            goto err;
+        }
+    }
+    else
+    {
+        int ri, wi;
+        int one = -1;
+        int n = 0;
+
+        we_get_rw_indices(wes, event, &ri, &wi);
+        if (wi >= 0)
+        {
+            one = wi;
+            ++n;
+        }
+        if (ri >= 0)
+        {
+            one = ri;
+            ++n;
+        }
+        switch (rwflags)
+        {
+            case 0:
+                switch (n)
+                {
+                    case 0:
+                        break;
+
+                    case 1:
+                        we_del_index(wes, one);
+                        break;
+
+                    case 2:
+                        we_del_event(wes, event);
+                        break;
+
+                    default:
+                        ASSERT(0);
+                }
+                break;
+
+            case EVENT_READ:
+                switch (n)
+                {
+                    case 0:
+                        if (!we_append_event(wes, event, EVENT_READ, arg))
+                        {
+                            goto err;
+                        }
+                        break;
+
+                    case 1:
+                        we_set_event(wes, one, event, EVENT_READ, arg);
+                        break;
+
+                    case 2:
+                        we_del_index(wes, wi);
+                        break;
+
+                    default:
+                        ASSERT(0);
+                }
+                break;
+
+            case EVENT_WRITE:
+                switch (n)
+                {
+                    case 0:
+                        if (!we_append_event(wes, event, EVENT_WRITE, arg))
+                        {
+                            goto err;
+                        }
+                        break;
+
+                    case 1:
+                        we_set_event(wes, one, event, EVENT_WRITE, arg);
+                        break;
+
+                    case 2:
+                        we_del_index(wes, ri);
+                        break;
+
+                    default:
+                        ASSERT(0);
+                }
+                break;
+
+            case EVENT_READ|EVENT_WRITE:
+                switch (n)
+                {
+                    case 0:
+                        if (!we_append_event(wes, event, EVENT_READ|EVENT_WRITE, arg))
+                        {
+                            goto err;
+                        }
+                        break;
+
+                    case 1:
+                        if (ri == -1)
+                        {
+                            ASSERT(wi != -1);
+                            if (!we_append_event(wes, event, EVENT_READ, arg))
+                            {
+                                goto err;
+                            }
+                        }
+                        else if (wi == -1)
+                        {
+                            if (!we_append_event(wes, event, EVENT_WRITE, arg))
+                            {
+                                goto err;
+                            }
+                        }
+                        else
+                        {
+                            ASSERT(0);
+                        }
+                        break;
+
+                    case 2:
+                        break;
+
+                    default:
+                        ASSERT(0);
+                }
+                break;
+
+            default:
+                msg(M_FATAL, "fatal error in we_ctl: rwflags=%d", rwflags);
+        }
+    }
+    return;
+
+err:
+    msg(D_EVENT_ERRORS, "Error: Windows resource limit WSA_MAXIMUM_WAIT_EVENTS (%d) has been exceeded", WSA_MAXIMUM_WAIT_EVENTS);
+}
+
+static int
+we_wait(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    struct we_set *wes = (struct we_set *) es;
+    const int timeout = tv_to_ms_timeout(tv);
+    DWORD status;
+
+    dmsg(D_EVENT_WAIT, "WE_WAIT enter n=%d to=%d", wes->n_events, timeout);
+
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_EVENT_WAIT))
+    {
+        int i;
+        for (i = 0; i < wes->n_events; ++i)
+        {
+            dmsg(D_EVENT_WAIT, "[%d] ev=%p rwflags=0x%04x arg=" ptr_format,
+                 i,
+                 wes->events[i],
+                 wes->esr[i].rwflags,
+                 (ptr_type)wes->esr[i].arg);
+        }
+    }
+#endif
+
+    /*
+     * First poll our event list with 0 timeout
+     */
+    status = WSAWaitForMultipleEvents(
+        (DWORD) wes->n_events,
+        wes->events,
+        FALSE,
+        (DWORD) 0,
+        FALSE);
+
+    /*
+     * If at least one event is already set, we must
+     * individually poll the whole list.
+     */
+    if (status >= WSA_WAIT_EVENT_0 && status < WSA_WAIT_EVENT_0 + (DWORD) wes->n_events)
+    {
+        int i;
+        int j = 0;
+        for (i = 0; i < wes->n_events; ++i)
+        {
+            if (j >= outlen)
+            {
+                break;
+            }
+            if (WaitForSingleObject(wes->events[i], 0) == WAIT_OBJECT_0)
+            {
+                *out = wes->esr[i];
+                dmsg(D_EVENT_WAIT, "WE_WAIT leave [%d,%d] rwflags=0x%04x arg=" ptr_format,
+                     i, j, out->rwflags, (ptr_type)out->arg);
+                ++j;
+                ++out;
+            }
+        }
+        return j;
+    }
+    else
+    {
+        /*
+         * If caller specified timeout > 0, we know at this point
+         * that no events are set, so wait only for the first event
+         * (or timeout) and return at most one event_set_return object.
+         *
+         * If caller specified timeout == 0, the second call to
+         * WSAWaitForMultipleEvents would be redundant -- just
+         * return 0 indicating timeout.
+         */
+        if (timeout > 0)
+        {
+            status = WSAWaitForMultipleEvents(
+                (DWORD) wes->n_events,
+                wes->events,
+                FALSE,
+                (DWORD) timeout,
+                FALSE);
+        }
+
+        if (outlen >= 1 && status >= WSA_WAIT_EVENT_0 && status < WSA_WAIT_EVENT_0 + (DWORD) wes->n_events)
+        {
+            *out = wes->esr[status - WSA_WAIT_EVENT_0];
+            dmsg(D_EVENT_WAIT, "WE_WAIT leave rwflags=0x%04x arg=" ptr_format,
+                 out->rwflags, (ptr_type)out->arg);
+            return 1;
+        }
+        else if (status == WSA_WAIT_TIMEOUT)
+        {
+            return 0;
+        }
+        else
+        {
+            return -1;
+        }
+    }
+}
+
+static struct event_set *
+we_init(int *maxevents, unsigned int flags)
+{
+    struct we_set *wes;
+
+    dmsg(D_EVENT_WAIT, "WE_INIT maxevents=%d flags=0x%08x", *maxevents, flags);
+
+    ALLOC_OBJ_CLEAR(wes, struct we_set);
+
+    /* set dispatch functions */
+    wes->func.free = we_free;
+    wes->func.reset = we_reset;
+    wes->func.del = we_del;
+    wes->func.ctl = we_ctl;
+    wes->func.wait = we_wait;
+
+    if (flags & EVENT_METHOD_FAST)
+    {
+        wes->fast = true;
+    }
+    wes->n_events = 0;
+
+    /* Figure our event capacity */
+    ASSERT(*maxevents > 0);
+    wes->capacity = min_int(*maxevents * 2, WSA_MAXIMUM_WAIT_EVENTS);
+    *maxevents = min_int(*maxevents, WSA_MAXIMUM_WAIT_EVENTS);
+
+    /* Allocate space for Win32 event handles */
+    ALLOC_ARRAY_CLEAR(wes->events, HANDLE, wes->capacity);
+
+    /* Allocate space for event_set_return objects */
+    ALLOC_ARRAY_CLEAR(wes->esr, struct event_set_return, wes->capacity);
+
+    dmsg(D_EVENT_WAIT, "WE_INIT maxevents=%d capacity=%d",
+         *maxevents, wes->capacity);
+
+    return (struct event_set *) wes;
+}
+
+#endif /* _WIN32 */
+
+#if EPOLL
+
+struct ep_set
+{
+    struct event_set_functions func;
+    bool fast;
+    int epfd;
+    int maxevents;
+    struct epoll_event *events;
+};
+
+static void
+ep_free(struct event_set *es)
+{
+    struct ep_set *eps = (struct ep_set *) es;
+    close(eps->epfd);
+    free(eps->events);
+    free(eps);
+}
+
+static void
+ep_reset(struct event_set *es)
+{
+    const struct ep_set *eps = (struct ep_set *) es;
+    ASSERT(eps->fast);
+}
+
+static void
+ep_del(struct event_set *es, event_t event)
+{
+    struct epoll_event ev;
+    struct ep_set *eps = (struct ep_set *) es;
+
+    dmsg(D_EVENT_WAIT, "EP_DEL ev=%d", (int)event);
+
+    ASSERT(!eps->fast);
+    CLEAR(ev);
+    epoll_ctl(eps->epfd, EPOLL_CTL_DEL, event, &ev);
+}
+
+static void
+ep_ctl(struct event_set *es, event_t event, unsigned int rwflags, void *arg)
+{
+    struct ep_set *eps = (struct ep_set *) es;
+    struct epoll_event ev;
+
+    CLEAR(ev);
+
+    ev.data.ptr = arg;
+    if (rwflags & EVENT_READ)
+    {
+        ev.events |= EPOLLIN;
+    }
+    if (rwflags & EVENT_WRITE)
+    {
+        ev.events |= EPOLLOUT;
+    }
+
+    dmsg(D_EVENT_WAIT, "EP_CTL fd=%d rwflags=0x%04x ev=0x%08x arg=" ptr_format,
+         (int)event,
+         rwflags,
+         (unsigned int)ev.events,
+         (ptr_type)ev.data.ptr);
+
+    if (epoll_ctl(eps->epfd, EPOLL_CTL_MOD, event, &ev) < 0)
+    {
+        if (errno == ENOENT)
+        {
+            if (epoll_ctl(eps->epfd, EPOLL_CTL_ADD, event, &ev) < 0)
+            {
+                msg(M_ERR, "EVENT: epoll_ctl EPOLL_CTL_ADD failed, sd=%d", (int)event);
+            }
+        }
+        else
+        {
+            msg(M_ERR, "EVENT: epoll_ctl EPOLL_CTL_MOD failed, sd=%d", (int)event);
+        }
+    }
+}
+
+static int
+ep_wait(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    struct ep_set *eps = (struct ep_set *) es;
+    int stat;
+
+    if (outlen > eps->maxevents)
+    {
+        outlen = eps->maxevents;
+    }
+
+    stat = epoll_wait(eps->epfd, eps->events, outlen, tv_to_ms_timeout(tv));
+    ASSERT(stat <= outlen);
+
+    if (stat > 0)
+    {
+        int i;
+        const struct epoll_event *ev = eps->events;
+        struct event_set_return *esr = out;
+        for (i = 0; i < stat; ++i)
+        {
+            esr->rwflags = 0;
+            if (ev->events & (EPOLLIN|EPOLLPRI|EPOLLERR|EPOLLHUP))
+            {
+                esr->rwflags |= EVENT_READ;
+            }
+            if (ev->events & EPOLLOUT)
+            {
+                esr->rwflags |= EVENT_WRITE;
+            }
+            esr->arg = ev->data.ptr;
+            dmsg(D_EVENT_WAIT, "EP_WAIT[%d] rwflags=0x%04x ev=0x%08x arg=" ptr_format,
+                 i, esr->rwflags, ev->events, (ptr_type)ev->data.ptr);
+            ++ev;
+            ++esr;
+        }
+    }
+    return stat;
+}
+
+static struct event_set *
+ep_init(int *maxevents, unsigned int flags)
+{
+    struct ep_set *eps;
+    int fd;
+
+    dmsg(D_EVENT_WAIT, "EP_INIT maxevents=%d flags=0x%08x", *maxevents, flags);
+
+    /* open epoll file descriptor */
+    fd = epoll_create(*maxevents);
+    if (fd < 0)
+    {
+        return NULL;
+    }
+
+    set_cloexec(fd);
+
+    ALLOC_OBJ_CLEAR(eps, struct ep_set);
+
+    /* set dispatch functions */
+    eps->func.free = ep_free;
+    eps->func.reset = ep_reset;
+    eps->func.del = ep_del;
+    eps->func.ctl = ep_ctl;
+    eps->func.wait = ep_wait;
+
+    /* fast method ("sort of") corresponds to epoll one-shot */
+    if (flags & EVENT_METHOD_FAST)
+    {
+        eps->fast = true;
+    }
+
+    /* allocate space for epoll_wait return */
+    ASSERT(*maxevents > 0);
+    eps->maxevents = *maxevents;
+    ALLOC_ARRAY_CLEAR(eps->events, struct epoll_event, eps->maxevents);
+
+    /* set epoll control fd */
+    eps->epfd = fd;
+
+    return (struct event_set *) eps;
+}
+#endif /* EPOLL */
+
+#if POLL
+
+struct po_set
+{
+    struct event_set_functions func;
+    bool fast;
+    struct pollfd *events;
+    void **args;
+    int n_events;
+    int capacity;
+};
+
+static void
+po_free(struct event_set *es)
+{
+    struct po_set *pos = (struct po_set *) es;
+    free(pos->events);
+    free(pos->args);
+    free(pos);
+}
+
+static void
+po_reset(struct event_set *es)
+{
+    struct po_set *pos = (struct po_set *) es;
+    ASSERT(pos->fast);
+    pos->n_events = 0;
+}
+
+static void
+po_del(struct event_set *es, event_t event)
+{
+    struct po_set *pos = (struct po_set *) es;
+    int i;
+
+    dmsg(D_EVENT_WAIT, "PO_DEL ev=%d", (int)event);
+
+    ASSERT(!pos->fast);
+    for (i = 0; i < pos->n_events; ++i)
+    {
+        if (pos->events[i].fd == event)
+        {
+            int j;
+            for (j = i; j < pos->n_events - 1; ++j)
+            {
+                pos->events[j] = pos->events[j+1];
+                pos->args[j] = pos->args[j+1];
+            }
+            --pos->n_events;
+            break;
+        }
+    }
+}
+
+static inline void
+po_set_pollfd_events(struct pollfd *pfdp, unsigned int rwflags)
+{
+    pfdp->events = 0;
+    if (rwflags & EVENT_WRITE)
+    {
+        pfdp->events |= POLLOUT;
+    }
+    if (rwflags & EVENT_READ)
+    {
+        pfdp->events |= (POLLIN|POLLPRI);
+    }
+}
+
+static inline bool
+po_append_event(struct po_set *pos, event_t event, unsigned int rwflags, void *arg)
+{
+    if (pos->n_events < pos->capacity)
+    {
+        struct pollfd *pfdp = &pos->events[pos->n_events];
+        pfdp->fd = event;
+        pos->args[pos->n_events] = arg;
+        po_set_pollfd_events(pfdp, rwflags);
+        ++pos->n_events;
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static void
+po_ctl(struct event_set *es, event_t event, unsigned int rwflags, void *arg)
+{
+    struct po_set *pos = (struct po_set *) es;
+
+    dmsg(D_EVENT_WAIT, "PO_CTL rwflags=0x%04x ev=%d arg=" ptr_format,
+         rwflags, (int)event, (ptr_type)arg);
+
+    if (pos->fast)
+    {
+        if (!po_append_event(pos, event, rwflags, arg))
+        {
+            goto err;
+        }
+    }
+    else
+    {
+        int i;
+        for (i = 0; i < pos->n_events; ++i)
+        {
+            struct pollfd *pfdp = &pos->events[i];
+            if (pfdp->fd == event)
+            {
+                pos->args[i] = arg;
+                po_set_pollfd_events(pfdp, rwflags);
+                goto done;
+            }
+        }
+        if (!po_append_event(pos, event, rwflags, arg))
+        {
+            goto err;
+        }
+    }
+
+done:
+    return;
+
+err:
+    msg(D_EVENT_ERRORS, "Error: poll: too many I/O wait events");
+}
+
+static int
+po_wait(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    struct po_set *pos = (struct po_set *) es;
+    int stat;
+
+    stat = poll(pos->events, pos->n_events, tv_to_ms_timeout(tv));
+
+    ASSERT(stat <= pos->n_events);
+
+    if (stat > 0)
+    {
+        int i, j = 0;
+        const struct pollfd *pfdp = pos->events;
+        for (i = 0; i < pos->n_events && j < outlen; ++i)
+        {
+            if (pfdp->revents & (POLLIN|POLLPRI|POLLERR|POLLHUP|POLLOUT))
+            {
+                out->rwflags = 0;
+                if (pfdp->revents & (POLLIN|POLLPRI|POLLERR|POLLHUP))
+                {
+                    out->rwflags |= EVENT_READ;
+                }
+                if (pfdp->revents & POLLOUT)
+                {
+                    out->rwflags |= EVENT_WRITE;
+                }
+                out->arg = pos->args[i];
+                dmsg(D_EVENT_WAIT, "PO_WAIT[%d,%d] fd=%d rev=0x%08x rwflags=0x%04x arg=" ptr_format " %s",
+                     i, j, pfdp->fd, pfdp->revents, out->rwflags, (ptr_type)out->arg, pos->fast ? "" : "[scalable]");
+                ++out;
+                ++j;
+            }
+            else if (pfdp->revents)
+            {
+                msg(D_EVENT_ERRORS, "Error: poll: unknown revents=0x%04x", (unsigned int)pfdp->revents);
+            }
+            ++pfdp;
+        }
+        return j;
+    }
+    return stat;
+}
+
+static struct event_set *
+po_init(int *maxevents, unsigned int flags)
+{
+    struct po_set *pos;
+
+    dmsg(D_EVENT_WAIT, "PO_INIT maxevents=%d flags=0x%08x", *maxevents, flags);
+
+    ALLOC_OBJ_CLEAR(pos, struct po_set);
+
+    /* set dispatch functions */
+    pos->func.free = po_free;
+    pos->func.reset = po_reset;
+    pos->func.del = po_del;
+    pos->func.ctl = po_ctl;
+    pos->func.wait = po_wait;
+
+    if (flags & EVENT_METHOD_FAST)
+    {
+        pos->fast = true;
+    }
+
+    pos->n_events = 0;
+
+    /* Figure our event capacity */
+    ASSERT(*maxevents > 0);
+    pos->capacity = *maxevents;
+
+    /* Allocate space for pollfd structures to be passed to poll() */
+    ALLOC_ARRAY_CLEAR(pos->events, struct pollfd, pos->capacity);
+
+    /* Allocate space for event_set_return objects */
+    ALLOC_ARRAY_CLEAR(pos->args, void *, pos->capacity);
+
+    return (struct event_set *) pos;
+}
+#endif /* POLL */
+
+#if SELECT
+
+struct se_set
+{
+    struct event_set_functions func;
+    bool fast;
+    fd_set readfds;
+    fd_set writefds;
+    void **args; /* allocated to capacity size */
+    int maxfd;  /* largest fd seen so far, always < capacity */
+    int capacity; /* fixed largest fd + 1 */
+};
+
+static void
+se_free(struct event_set *es)
+{
+    struct se_set *ses = (struct se_set *) es;
+    free(ses->args);
+    free(ses);
+}
+
+static void
+se_reset(struct event_set *es)
+{
+    struct se_set *ses = (struct se_set *) es;
+    int i;
+    ASSERT(ses->fast);
+
+    dmsg(D_EVENT_WAIT, "SE_RESET");
+
+    FD_ZERO(&ses->readfds);
+    FD_ZERO(&ses->writefds);
+    for (i = 0; i <= ses->maxfd; ++i)
+    {
+        ses->args[i] = NULL;
+    }
+    ses->maxfd = -1;
+}
+
+static void
+se_del(struct event_set *es, event_t event)
+{
+    struct se_set *ses = (struct se_set *) es;
+    ASSERT(!ses->fast);
+
+    dmsg(D_EVENT_WAIT, "SE_DEL ev=%d", (int)event);
+
+    if (event >= 0 && event < ses->capacity)
+    {
+        FD_CLR(event, &ses->readfds);
+        FD_CLR(event, &ses->writefds);
+        ses->args[event] = NULL;
+    }
+    else
+    {
+        msg(D_EVENT_ERRORS, "Error: select/se_del: too many I/O wait events");
+    }
+    return;
+}
+
+static void
+se_ctl(struct event_set *es, event_t event, unsigned int rwflags, void *arg)
+{
+    struct se_set *ses = (struct se_set *) es;
+
+    dmsg(D_EVENT_WAIT, "SE_CTL rwflags=0x%04x ev=%d fast=%d cap=%d maxfd=%d arg=" ptr_format,
+         rwflags, (int)event, (int)ses->fast, ses->capacity, ses->maxfd, (ptr_type)arg);
+
+    if (event >= 0 && event < ses->capacity)
+    {
+        ses->maxfd = max_int(event, ses->maxfd);
+        ses->args[event] = arg;
+        if (ses->fast)
+        {
+            if (rwflags & EVENT_READ)
+            {
+                openvpn_fd_set(event, &ses->readfds);
+            }
+            if (rwflags & EVENT_WRITE)
+            {
+                openvpn_fd_set(event, &ses->writefds);
+            }
+        }
+        else
+        {
+            if (rwflags & EVENT_READ)
+            {
+                openvpn_fd_set(event, &ses->readfds);
+            }
+            else
+            {
+                FD_CLR(event, &ses->readfds);
+            }
+            if (rwflags & EVENT_WRITE)
+            {
+                openvpn_fd_set(event, &ses->writefds);
+            }
+            else
+            {
+                FD_CLR(event, &ses->writefds);
+            }
+        }
+    }
+    else
+    {
+        msg(D_EVENT_ERRORS, "Error: select: too many I/O wait events, fd=%d cap=%d",
+            (int) event,
+            ses->capacity);
+    }
+}
+
+static int
+se_wait_return(struct se_set *ses,
+               fd_set *read,
+               fd_set *write,
+               struct event_set_return *out,
+               int outlen)
+{
+    int i, j = 0;
+    for (i = 0; i <= ses->maxfd && j < outlen; ++i)
+    {
+        const bool r = FD_ISSET(i, read);
+        const bool w = FD_ISSET(i, write);
+        if (r || w)
+        {
+            out->rwflags = 0;
+            if (r)
+            {
+                out->rwflags |= EVENT_READ;
+            }
+            if (w)
+            {
+                out->rwflags |= EVENT_WRITE;
+            }
+            out->arg = ses->args[i];
+            dmsg(D_EVENT_WAIT, "SE_WAIT[%d,%d] rwflags=0x%04x arg=" ptr_format,
+                 i, j, out->rwflags, (ptr_type)out->arg);
+            ++out;
+            ++j;
+        }
+    }
+    return j;
+}
+
+static int
+se_wait_fast(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    struct se_set *ses = (struct se_set *) es;
+    struct timeval tv_tmp = *tv;
+    int stat;
+
+    dmsg(D_EVENT_WAIT, "SE_WAIT_FAST maxfd=%d tv=%d/%d",
+         ses->maxfd,
+         (int)tv_tmp.tv_sec,
+         (int)tv_tmp.tv_usec);
+
+    stat = select(ses->maxfd + 1, &ses->readfds, &ses->writefds, NULL, &tv_tmp);
+
+    if (stat > 0)
+    {
+        stat = se_wait_return(ses, &ses->readfds, &ses->writefds, out, outlen);
+    }
+
+    return stat;
+}
+
+static int
+se_wait_scalable(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    struct se_set *ses = (struct se_set *) es;
+    struct timeval tv_tmp = *tv;
+    fd_set read = ses->readfds;
+    fd_set write = ses->writefds;
+    int stat;
+
+    dmsg(D_EVENT_WAIT, "SE_WAIT_SCALEABLE maxfd=%d tv=%d/%d",
+         ses->maxfd, (int)tv_tmp.tv_sec, (int)tv_tmp.tv_usec);
+
+    stat = select(ses->maxfd + 1, &read, &write, NULL, &tv_tmp);
+
+    if (stat > 0)
+    {
+        stat = se_wait_return(ses, &read, &write, out, outlen);
+    }
+
+    return stat;
+}
+
+static struct event_set *
+se_init(int *maxevents, unsigned int flags)
+{
+    struct se_set *ses;
+
+    dmsg(D_EVENT_WAIT, "SE_INIT maxevents=%d flags=0x%08x", *maxevents, flags);
+
+    ALLOC_OBJ_CLEAR(ses, struct se_set);
+
+    /* set dispatch functions */
+    ses->func.free = se_free;
+    ses->func.reset = se_reset;
+    ses->func.del = se_del;
+    ses->func.ctl = se_ctl;
+    ses->func.wait = se_wait_scalable;
+
+    if (flags & EVENT_METHOD_FAST)
+    {
+        ses->fast = true;
+        ses->func.wait = se_wait_fast;
+    }
+
+    /* Select needs to be passed this value + 1 */
+    ses->maxfd = -1;
+
+    /* Set our event capacity */
+    ASSERT(*maxevents > 0);
+    *maxevents = min_int(*maxevents, SELECT_MAX_FDS);
+    ses->capacity = SELECT_MAX_FDS;
+
+    /* Allocate space for event_set_return void * args */
+    ALLOC_ARRAY_CLEAR(ses->args, void *, ses->capacity);
+
+    return (struct event_set *) ses;
+}
+#endif /* SELECT */
+
+static struct event_set *
+event_set_init_simple(int *maxevents, unsigned int flags)
+{
+    struct event_set *ret = NULL;
+#ifdef _WIN32
+    ret = we_init(maxevents, flags);
+#elif POLL && SELECT
+#if 0 /* Define to 1 if EVENT_METHOD_US_TIMEOUT should cause select to be favored over poll */
+    if (flags & EVENT_METHOD_US_TIMEOUT)
+    {
+        ret = se_init(maxevents, flags);
+    }
+#endif
+#ifdef SELECT_PREFERRED_OVER_POLL
+    if (!ret)
+    {
+        ret = se_init(maxevents, flags);
+    }
+    if (!ret)
+    {
+        ret = po_init(maxevents, flags);
+    }
+#else  /* ifdef SELECT_PREFERRED_OVER_POLL */
+    if (!ret)
+    {
+        ret = po_init(maxevents, flags);
+    }
+    if (!ret)
+    {
+        ret = se_init(maxevents, flags);
+    }
+#endif
+#elif POLL
+    ret = po_init(maxevents, flags);
+#elif SELECT
+    ret = se_init(maxevents, flags);
+#else  /* ifdef _WIN32 */
+#error At least one of poll, select, or WSAWaitForMultipleEvents must be supported by the kernel
+#endif /* ifdef _WIN32 */
+    ASSERT(ret);
+    return ret;
+}
+
+static struct event_set *
+event_set_init_scalable(int *maxevents, unsigned int flags)
+{
+    struct event_set *ret = NULL;
+#if EPOLL
+    ret = ep_init(maxevents, flags);
+    if (!ret)
+    {
+        msg(M_WARN, "Note: sys_epoll API is unavailable, falling back to poll/select API");
+        ret = event_set_init_simple(maxevents, flags);
+    }
+#else  /* if EPOLL */
+    ret = event_set_init_simple(maxevents, flags);
+#endif
+    ASSERT(ret);
+    return ret;
+}
+
+struct event_set *
+event_set_init(int *maxevents, unsigned int flags)
+{
+    if (flags & EVENT_METHOD_FAST)
+    {
+        return event_set_init_simple(maxevents, flags);
+    }
+    else
+    {
+        return event_set_init_scalable(maxevents, flags);
+    }
+}
diff --git a/src/openvpn/event.h b/src/openvpn/event.h
new file mode 100644
index 0000000..4af6371
--- /dev/null
+++ b/src/openvpn/event.h
@@ -0,0 +1,161 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef EVENT_H
+#define EVENT_H
+
+#include "win32.h"
+#include "sig.h"
+#include "perf.h"
+
+/*
+ * rwflags passed to event_ctl and returned by
+ * struct event_set_return.
+ */
+#define EVENT_UNDEF    4
+#define EVENT_READ     (1<<0)
+#define EVENT_WRITE    (1<<1)
+/*
+ * Initialization flags passed to event_set_init
+ */
+#define EVENT_METHOD_US_TIMEOUT   (1<<0)
+#define EVENT_METHOD_FAST         (1<<1)
+
+#ifdef _WIN32
+
+typedef const struct rw_handle *event_t;
+
+#define UNDEFINED_EVENT (NULL)
+
+#else  /* ifdef _WIN32 */
+
+typedef int event_t;
+
+#define UNDEFINED_EVENT (-1)
+
+#endif
+
+struct event_set;
+struct event_set_return;
+
+struct event_set_functions
+{
+    void (*free)(struct event_set *es);
+    void (*reset)(struct event_set *es);
+    void (*del)(struct event_set *es, event_t event);
+    void (*ctl)(struct event_set *es, event_t event, unsigned int rwflags, void *arg);
+
+    /*
+     * Return status for wait:
+     * -1 on signal or error
+     * 0 on timeout
+     * length of event_set_return if at least 1 event is returned
+     */
+    int (*wait)(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen);
+};
+
+struct event_set_return
+{
+    unsigned int rwflags;
+    void *arg;
+};
+
+struct event_set
+{
+    struct event_set_functions func;
+};
+
+/*
+ * maxevents on input:  desired max number of event_t descriptors
+ *                      simultaneously set with event_ctl
+ * maxevents on output: may be modified down, depending on limitations
+ *                      of underlying API
+ * flags:               EVENT_METHOD_x flags
+ */
+struct event_set *event_set_init(int *maxevents, unsigned int flags);
+
+static inline void
+event_free(struct event_set *es)
+{
+    if (es)
+    {
+        (*es->func.free)(es);
+    }
+}
+
+static inline void
+event_reset(struct event_set *es)
+{
+    (*es->func.reset)(es);
+}
+
+static inline void
+event_del(struct event_set *es, event_t event)
+{
+    (*es->func.del)(es, event);
+}
+
+static inline void
+event_ctl(struct event_set *es, event_t event, unsigned int rwflags, void *arg)
+{
+    (*es->func.ctl)(es, event, rwflags, arg);
+}
+
+static inline int
+event_wait(struct event_set *es, const struct timeval *tv, struct event_set_return *out, int outlen)
+{
+    int ret;
+    perf_push(PERF_IO_WAIT);
+    ret = (*es->func.wait)(es, tv, out, outlen);
+    perf_pop();
+    return ret;
+}
+
+static inline void
+event_set_return_init(struct event_set_return *esr)
+{
+    esr->rwflags = 0;
+    esr->arg = NULL;
+}
+
+#ifdef _WIN32
+
+static inline void
+wait_signal(struct event_set *es, void *arg)
+{
+    if (HANDLE_DEFINED(win32_signal.in.read))
+    {
+        event_ctl(es, &win32_signal.in, EVENT_READ, arg);
+    }
+}
+
+#else  /* ifdef _WIN32 */
+
+static inline void
+wait_signal(struct event_set *es, void *arg)
+{
+}
+
+#endif
+
+#endif /* ifndef EVENT_H */
diff --git a/src/openvpn/fdmisc.c b/src/openvpn/fdmisc.c
new file mode 100644
index 0000000..1cea505
--- /dev/null
+++ b/src/openvpn/fdmisc.c
@@ -0,0 +1,87 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "fdmisc.h"
+#include "error.h"
+
+#include "memdbg.h"
+
+/* Set a file descriptor to non-blocking */
+bool
+set_nonblock_action(int fd)
+{
+#ifdef _WIN32
+    u_long arg = 1;
+    if (ioctlsocket(fd, FIONBIO, &arg))
+    {
+        return false;
+    }
+#else  /* ifdef _WIN32 */
+    if (fcntl(fd, F_SETFL, O_NONBLOCK) < 0)
+    {
+        return false;
+    }
+#endif
+    return true;
+}
+
+/* Set a file descriptor to not be passed across execs */
+bool
+set_cloexec_action(int fd)
+{
+#ifndef _WIN32
+    if (fcntl(fd, F_SETFD, FD_CLOEXEC) < 0)
+    {
+        return false;
+    }
+#endif
+    return true;
+}
+
+/* Set a file descriptor to non-blocking */
+void
+set_nonblock(int fd)
+{
+    if (!set_nonblock_action(fd))
+    {
+        msg(M_ERR, "Set socket to non-blocking mode failed");
+    }
+}
+
+/* Set a file descriptor to not be passed across execs */
+void
+set_cloexec(int fd)
+{
+    if (!set_cloexec_action(fd))
+    {
+        msg(M_ERR, "Set FD_CLOEXEC flag on file descriptor failed");
+    }
+}
diff --git a/src/openvpn/fdmisc.h b/src/openvpn/fdmisc.h
new file mode 100644
index 0000000..0fb8b93
--- /dev/null
+++ b/src/openvpn/fdmisc.h
@@ -0,0 +1,49 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef FD_MISC_H
+#define FD_MISC_H
+
+#include "basic.h"
+#include "error.h"
+#include "syshead.h"
+
+bool set_nonblock_action(int fd);
+
+bool set_cloexec_action(int fd);
+
+void set_nonblock(int fd);
+
+void set_cloexec(int fd);
+
+static inline void
+openvpn_fd_set(int fd, fd_set *setp)
+{
+#ifndef _WIN32 /* The Windows FD_SET() implementation does not overflow */
+    ASSERT(fd >= 0 && fd < FD_SETSIZE);
+#endif
+    FD_SET(fd, setp);
+}
+#undef FD_SET /* prevent direct use of FD_SET() */
+
+#endif /* FD_MISC_H */
diff --git a/src/openvpn/forward-inline.h b/src/openvpn/forward-inline.h
new file mode 100644
index 0000000..7d06b4e
--- /dev/null
+++ b/src/openvpn/forward-inline.h
@@ -0,0 +1,341 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef FORWARD_INLINE_H
+#define FORWARD_INLINE_H
+
+/*
+ * Inline functions
+ */
+
+/*
+ * Does TLS session need service?
+ */
+static inline void
+check_tls(struct context *c)
+{
+#if defined(ENABLE_CRYPTO)
+    void check_tls_dowork(struct context *c);
+
+    if (c->c2.tls_multi)
+    {
+        check_tls_dowork(c);
+    }
+#endif
+}
+
+/*
+ * TLS errors are fatal in TCP mode.
+ * Also check for --tls-exit trigger.
+ */
+static inline void
+check_tls_errors(struct context *c)
+{
+#if defined(ENABLE_CRYPTO)
+    void check_tls_errors_co(struct context *c);
+
+    void check_tls_errors_nco(struct context *c);
+
+    if (c->c2.tls_multi && c->c2.tls_exit_signal)
+    {
+        if (link_socket_connection_oriented(c->c2.link_socket))
+        {
+            if (c->c2.tls_multi->n_soft_errors)
+            {
+                check_tls_errors_co(c);
+            }
+        }
+        else
+        {
+            if (c->c2.tls_multi->n_hard_errors)
+            {
+                check_tls_errors_nco(c);
+            }
+        }
+    }
+#endif /* if defined(ENABLE_CRYPTO) */
+}
+
+/*
+ * Check for possible incoming configuration
+ * messages on the control channel.
+ */
+static inline void
+check_incoming_control_channel(struct context *c)
+{
+#if P2MP
+    void check_incoming_control_channel_dowork(struct context *c);
+
+    if (tls_test_payload_len(c->c2.tls_multi) > 0)
+    {
+        check_incoming_control_channel_dowork(c);
+    }
+#endif
+}
+
+/*
+ * Options like --up-delay need to be triggered by this function which
+ * checks for connection establishment.
+ */
+static inline void
+check_connection_established(struct context *c)
+{
+    void check_connection_established_dowork(struct context *c);
+
+    if (event_timeout_defined(&c->c2.wait_for_connect))
+    {
+        check_connection_established_dowork(c);
+    }
+}
+
+/*
+ * Should we add routes?
+ */
+static inline void
+check_add_routes(struct context *c)
+{
+    void check_add_routes_dowork(struct context *c);
+
+    if (event_timeout_trigger(&c->c2.route_wakeup, &c->c2.timeval, ETT_DEFAULT))
+    {
+        check_add_routes_dowork(c);
+    }
+}
+
+/*
+ * Should we exit due to inactivity timeout?
+ */
+static inline void
+check_inactivity_timeout(struct context *c)
+{
+    void check_inactivity_timeout_dowork(struct context *c);
+
+    if (c->options.inactivity_timeout
+        && event_timeout_trigger(&c->c2.inactivity_interval, &c->c2.timeval, ETT_DEFAULT))
+    {
+        check_inactivity_timeout_dowork(c);
+    }
+}
+
+#if P2MP
+
+static inline void
+check_server_poll_timeout(struct context *c)
+{
+    void check_server_poll_timeout_dowork(struct context *c);
+
+    if (c->options.ce.connect_timeout
+        && event_timeout_trigger(&c->c2.server_poll_interval, &c->c2.timeval, ETT_DEFAULT))
+    {
+        check_server_poll_timeout_dowork(c);
+    }
+}
+
+/*
+ * Scheduled exit?
+ */
+static inline void
+check_scheduled_exit(struct context *c)
+{
+    void check_scheduled_exit_dowork(struct context *c);
+
+    if (event_timeout_defined(&c->c2.scheduled_exit))
+    {
+        if (event_timeout_trigger(&c->c2.scheduled_exit, &c->c2.timeval, ETT_DEFAULT))
+        {
+            check_scheduled_exit_dowork(c);
+        }
+    }
+}
+#endif /* if P2MP */
+
+/*
+ * Should we write timer-triggered status file.
+ */
+static inline void
+check_status_file(struct context *c)
+{
+    void check_status_file_dowork(struct context *c);
+
+    if (c->c1.status_output)
+    {
+        if (status_trigger_tv(c->c1.status_output, &c->c2.timeval))
+        {
+            check_status_file_dowork(c);
+        }
+    }
+}
+
+#ifdef ENABLE_FRAGMENT
+/*
+ * Should we deliver a datagram fragment to remote?
+ */
+static inline void
+check_fragment(struct context *c)
+{
+    void check_fragment_dowork(struct context *c);
+
+    if (c->c2.fragment)
+    {
+        check_fragment_dowork(c);
+    }
+}
+#endif
+
+#if P2MP
+
+/*
+ * see if we should send a push_request in response to --pull
+ */
+static inline void
+check_push_request(struct context *c)
+{
+    void check_push_request_dowork(struct context *c);
+
+    if (event_timeout_trigger(&c->c2.push_request_interval, &c->c2.timeval, ETT_DEFAULT))
+    {
+        check_push_request_dowork(c);
+    }
+}
+
+#endif
+
+#ifdef ENABLE_CRYPTO
+/*
+ * Should we persist our anti-replay packet ID state to disk?
+ */
+static inline void
+check_packet_id_persist_flush(struct context *c)
+{
+    if (packet_id_persist_enabled(&c->c1.pid_persist)
+        && event_timeout_trigger(&c->c2.packet_id_persist_interval, &c->c2.timeval, ETT_DEFAULT))
+    {
+        packet_id_persist_save(&c->c1.pid_persist);
+    }
+}
+#endif
+
+/*
+ * Set our wakeup to 0 seconds, so we will be rescheduled
+ * immediately.
+ */
+static inline void
+context_immediate_reschedule(struct context *c)
+{
+    c->c2.timeval.tv_sec = 0;  /* ZERO-TIMEOUT */
+    c->c2.timeval.tv_usec = 0;
+}
+
+static inline void
+context_reschedule_sec(struct context *c, int sec)
+{
+    if (sec < 0)
+    {
+        sec = 0;
+    }
+    if (sec < c->c2.timeval.tv_sec)
+    {
+        c->c2.timeval.tv_sec = sec;
+        c->c2.timeval.tv_usec = 0;
+    }
+}
+
+static inline struct link_socket_info *
+get_link_socket_info(struct context *c)
+{
+    if (c->c2.link_socket_info)
+    {
+        return c->c2.link_socket_info;
+    }
+    else
+    {
+        return &c->c2.link_socket->info;
+    }
+}
+
+static inline void
+register_activity(struct context *c, const int size)
+{
+    if (c->options.inactivity_timeout)
+    {
+        c->c2.inactivity_bytes += size;
+        if (c->c2.inactivity_bytes >= c->options.inactivity_minimum_bytes)
+        {
+            c->c2.inactivity_bytes = 0;
+            event_timeout_reset(&c->c2.inactivity_interval);
+        }
+    }
+}
+
+/*
+ * Return the io_wait() flags appropriate for
+ * a point-to-point tunnel.
+ */
+static inline unsigned int
+p2p_iow_flags(const struct context *c)
+{
+    unsigned int flags = (IOW_SHAPER|IOW_CHECK_RESIDUAL|IOW_FRAG|IOW_READ|IOW_WAIT_SIGNAL);
+    if (c->c2.to_link.len > 0)
+    {
+        flags |= IOW_TO_LINK;
+    }
+    if (c->c2.to_tun.len > 0)
+    {
+        flags |= IOW_TO_TUN;
+    }
+    return flags;
+}
+
+/*
+ * This is the core I/O wait function, used for all I/O waits except
+ * for TCP in server mode.
+ */
+static inline void
+io_wait(struct context *c, const unsigned int flags)
+{
+    void io_wait_dowork(struct context *c, const unsigned int flags);
+
+    if (c->c2.fast_io && (flags & (IOW_TO_TUN|IOW_TO_LINK|IOW_MBUF)))
+    {
+        /* fast path -- only for TUN/TAP/UDP writes */
+        unsigned int ret = 0;
+        if (flags & IOW_TO_TUN)
+        {
+            ret |= TUN_WRITE;
+        }
+        if (flags & (IOW_TO_LINK|IOW_MBUF))
+        {
+            ret |= SOCKET_WRITE;
+        }
+        c->c2.event_set_status = ret;
+    }
+    else
+    {
+        /* slow path */
+        io_wait_dowork(c, flags);
+    }
+}
+
+#define CONNECTION_ESTABLISHED(c) (get_link_socket_info(c)->connection_established)
+
+#endif /* EVENT_INLINE_H */
diff --git a/src/openvpn/forward.c b/src/openvpn/forward.c
new file mode 100644
index 0000000..84bb584
--- /dev/null
+++ b/src/openvpn/forward.c
@@ -0,0 +1,1858 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "forward.h"
+#include "init.h"
+#include "push.h"
+#include "gremlin.h"
+#include "mss.h"
+#include "event.h"
+#include "ps.h"
+#include "dhcp.h"
+#include "common.h"
+#include "ssl_verify.h"
+
+#include "memdbg.h"
+
+#include "forward-inline.h"
+#include "occ-inline.h"
+#include "ping-inline.h"
+#include "mstats.h"
+
+counter_type link_read_bytes_global;  /* GLOBAL */
+counter_type link_write_bytes_global; /* GLOBAL */
+
+/* show event wait debugging info */
+
+#ifdef ENABLE_DEBUG
+
+const char *
+wait_status_string(struct context *c, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    buf_printf(&out, "I/O WAIT %s|%s|%s|%s %s",
+               tun_stat(c->c1.tuntap, EVENT_READ, gc),
+               tun_stat(c->c1.tuntap, EVENT_WRITE, gc),
+               socket_stat(c->c2.link_socket, EVENT_READ, gc),
+               socket_stat(c->c2.link_socket, EVENT_WRITE, gc),
+               tv_string(&c->c2.timeval, gc));
+    return BSTR(&out);
+}
+
+void
+show_wait_status(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+    dmsg(D_EVENT_WAIT, "%s", wait_status_string(c, &gc));
+    gc_free(&gc);
+}
+
+#endif /* ifdef ENABLE_DEBUG */
+
+/*
+ * In TLS mode, let TLS level respond to any control-channel
+ * packets which were received, or prepare any packets for
+ * transmission.
+ *
+ * tmp_int is purely an optimization that allows us to call
+ * tls_multi_process less frequently when there's not much
+ * traffic on the control-channel.
+ *
+ */
+#ifdef ENABLE_CRYPTO
+void
+check_tls_dowork(struct context *c)
+{
+    interval_t wakeup = BIG_TIMEOUT;
+
+    if (interval_test(&c->c2.tmp_int))
+    {
+        const int tmp_status = tls_multi_process
+                                   (c->c2.tls_multi, &c->c2.to_link, &c->c2.to_link_addr,
+                                   get_link_socket_info(c), &wakeup);
+        if (tmp_status == TLSMP_ACTIVE)
+        {
+            update_time();
+            interval_action(&c->c2.tmp_int);
+        }
+        else if (tmp_status == TLSMP_KILL)
+        {
+            register_signal(c, SIGTERM, "auth-control-exit");
+        }
+
+        interval_future_trigger(&c->c2.tmp_int, wakeup);
+    }
+
+    interval_schedule_wakeup(&c->c2.tmp_int, &wakeup);
+
+    if (wakeup)
+    {
+        context_reschedule_sec(c, wakeup);
+    }
+}
+
+void
+check_tls_errors_co(struct context *c)
+{
+    msg(D_STREAM_ERRORS, "Fatal TLS error (check_tls_errors_co), restarting");
+    register_signal(c, c->c2.tls_exit_signal, "tls-error"); /* SOFT-SIGUSR1 -- TLS error */
+}
+
+void
+check_tls_errors_nco(struct context *c)
+{
+    register_signal(c, c->c2.tls_exit_signal, "tls-error"); /* SOFT-SIGUSR1 -- TLS error */
+}
+#endif /* ENABLE_CRYPTO */
+
+#if P2MP
+
+/*
+ * Handle incoming configuration
+ * messages on the control channel.
+ */
+void
+check_incoming_control_channel_dowork(struct context *c)
+{
+    const int len = tls_test_payload_len(c->c2.tls_multi);
+    if (len)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer buf = alloc_buf_gc(len, &gc);
+        if (tls_rec_payload(c->c2.tls_multi, &buf))
+        {
+            /* force null termination of message */
+            buf_null_terminate(&buf);
+
+            /* enforce character class restrictions */
+            string_mod(BSTR(&buf), CC_PRINT, CC_CRLF, 0);
+
+            if (buf_string_match_head_str(&buf, "AUTH_FAILED"))
+            {
+                receive_auth_failed(c, &buf);
+            }
+            else if (buf_string_match_head_str(&buf, "PUSH_"))
+            {
+                incoming_push_message(c, &buf);
+            }
+            else if (buf_string_match_head_str(&buf, "RESTART"))
+            {
+                server_pushed_signal(c, &buf, true, 7);
+            }
+            else if (buf_string_match_head_str(&buf, "HALT"))
+            {
+                server_pushed_signal(c, &buf, false, 4);
+            }
+            else
+            {
+                msg(D_PUSH_ERRORS, "WARNING: Received unknown control message: %s", BSTR(&buf));
+            }
+        }
+        else
+        {
+            msg(D_PUSH_ERRORS, "WARNING: Receive control message failed");
+        }
+
+        gc_free(&gc);
+    }
+}
+
+/*
+ * Periodically resend PUSH_REQUEST until PUSH message received
+ */
+void
+check_push_request_dowork(struct context *c)
+{
+    send_push_request(c);
+
+    /* if no response to first push_request, retry at PUSH_REQUEST_INTERVAL second intervals */
+    event_timeout_modify_wakeup(&c->c2.push_request_interval, PUSH_REQUEST_INTERVAL);
+}
+
+#endif /* P2MP */
+
+/*
+ * Things that need to happen immediately after connection initiation should go here.
+ */
+void
+check_connection_established_dowork(struct context *c)
+{
+    if (event_timeout_trigger(&c->c2.wait_for_connect, &c->c2.timeval, ETT_DEFAULT))
+    {
+        if (CONNECTION_ESTABLISHED(c))
+        {
+#if P2MP
+            /* if --pull was specified, send a push request to server */
+            if (c->c2.tls_multi && c->options.pull)
+            {
+#ifdef ENABLE_MANAGEMENT
+                if (management)
+                {
+                    management_set_state(management,
+                                         OPENVPN_STATE_GET_CONFIG,
+                                         NULL,
+                                         NULL,
+                                         NULL,
+                                         NULL,
+                                         NULL);
+                }
+#endif
+                /* fire up push request right away (already 1s delayed) */
+                event_timeout_init(&c->c2.push_request_interval, 0, now);
+                reset_coarse_timers(c);
+            }
+            else
+#endif /* if P2MP */
+            {
+                do_up(c, false, 0);
+            }
+
+            event_timeout_clear(&c->c2.wait_for_connect);
+        }
+    }
+}
+
+/*
+ * Send a string to remote over the TLS control channel.
+ * Used for push/pull messages, passing username/password,
+ * etc.
+ */
+bool
+send_control_channel_string(struct context *c, const char *str, int msglevel)
+{
+#ifdef ENABLE_CRYPTO
+    if (c->c2.tls_multi)
+    {
+        struct gc_arena gc = gc_new();
+        bool stat;
+
+        /* buffered cleartext write onto TLS control channel */
+        stat = tls_send_payload(c->c2.tls_multi, (uint8_t *) str, strlen(str) + 1);
+
+        /*
+         * Reschedule tls_multi_process.
+         * NOTE: in multi-client mode, usually the below two statements are
+         * insufficient to reschedule the client instance object unless
+         * multi_schedule_context_wakeup(m, mi) is also called.
+         */
+        interval_action(&c->c2.tmp_int);
+        context_immediate_reschedule(c); /* ZERO-TIMEOUT */
+
+        msg(msglevel, "SENT CONTROL [%s]: '%s' (status=%d)",
+            tls_common_name(c->c2.tls_multi, false),
+            sanitize_control_message(str, &gc),
+            (int) stat);
+
+        gc_free(&gc);
+        return stat;
+    }
+#endif /* ENABLE_CRYPTO */
+    return true;
+}
+
+/*
+ * Add routes.
+ */
+
+static void
+check_add_routes_action(struct context *c, const bool errors)
+{
+    do_route(&c->options, c->c1.route_list, c->c1.route_ipv6_list,
+             c->c1.tuntap, c->plugins, c->c2.es);
+    update_time();
+    event_timeout_clear(&c->c2.route_wakeup);
+    event_timeout_clear(&c->c2.route_wakeup_expire);
+    initialization_sequence_completed(c, errors ? ISC_ERRORS : 0); /* client/p2p --route-delay was defined */
+}
+
+void
+check_add_routes_dowork(struct context *c)
+{
+    if (test_routes(c->c1.route_list, c->c1.tuntap))
+    {
+        check_add_routes_action(c, false);
+    }
+    else if (event_timeout_trigger(&c->c2.route_wakeup_expire, &c->c2.timeval, ETT_DEFAULT))
+    {
+        check_add_routes_action(c, true);
+    }
+    else
+    {
+        msg(D_ROUTE, "Route: Waiting for TUN/TAP interface to come up...");
+        if (c->c1.tuntap)
+        {
+            if (!tun_standby(c->c1.tuntap))
+            {
+                register_signal(c, SIGHUP, "ip-fail");
+                c->persist.restart_sleep_seconds = 10;
+#ifdef _WIN32
+                show_routes(M_INFO|M_NOPREFIX);
+                show_adapters(M_INFO|M_NOPREFIX);
+#endif
+            }
+        }
+        update_time();
+        if (c->c2.route_wakeup.n != 1)
+        {
+            event_timeout_init(&c->c2.route_wakeup, 1, now);
+        }
+        event_timeout_reset(&c->c2.ping_rec_interval);
+    }
+}
+
+/*
+ * Should we exit due to inactivity timeout?
+ */
+void
+check_inactivity_timeout_dowork(struct context *c)
+{
+    msg(M_INFO, "Inactivity timeout (--inactive), exiting");
+    register_signal(c, SIGTERM, "inactive");
+}
+
+int
+get_server_poll_remaining_time(struct event_timeout *server_poll_timeout)
+{
+    update_time();
+    int remaining = event_timeout_remaining(server_poll_timeout);
+    return max_int(0, remaining);
+}
+#if P2MP
+
+void
+check_server_poll_timeout_dowork(struct context *c)
+{
+    event_timeout_reset(&c->c2.server_poll_interval);
+    ASSERT(c->c2.tls_multi);
+    if (!tls_initial_packet_received(c->c2.tls_multi))
+    {
+        msg(M_INFO, "Server poll timeout, restarting");
+        register_signal(c, SIGUSR1, "server_poll");
+        c->persist.restart_sleep_seconds = -1;
+    }
+}
+
+/*
+ * Schedule a signal n_seconds from now.
+ */
+void
+schedule_exit(struct context *c, const int n_seconds, const int signal)
+{
+    tls_set_single_session(c->c2.tls_multi);
+    update_time();
+    reset_coarse_timers(c);
+    event_timeout_init(&c->c2.scheduled_exit, n_seconds, now);
+    c->c2.scheduled_exit_signal = signal;
+    msg(D_SCHED_EXIT, "Delayed exit in %d seconds", n_seconds);
+}
+
+/*
+ * Scheduled exit?
+ */
+void
+check_scheduled_exit_dowork(struct context *c)
+{
+    register_signal(c, c->c2.scheduled_exit_signal, "delayed-exit");
+}
+
+#endif /* if P2MP */
+
+/*
+ * Should we write timer-triggered status file.
+ */
+void
+check_status_file_dowork(struct context *c)
+{
+    if (c->c1.status_output)
+    {
+        print_status(c, c->c1.status_output);
+    }
+}
+
+#ifdef ENABLE_FRAGMENT
+/*
+ * Should we deliver a datagram fragment to remote?
+ */
+void
+check_fragment_dowork(struct context *c)
+{
+    struct link_socket_info *lsi = get_link_socket_info(c);
+
+    /* OS MTU Hint? */
+    if (lsi->mtu_changed)
+    {
+        frame_adjust_path_mtu(&c->c2.frame_fragment, c->c2.link_socket->mtu,
+                              c->options.ce.proto);
+        lsi->mtu_changed = false;
+    }
+
+    if (fragment_outgoing_defined(c->c2.fragment))
+    {
+        if (!c->c2.to_link.len)
+        {
+            /* encrypt a fragment for output to TCP/UDP port */
+            ASSERT(fragment_ready_to_send(c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment));
+            encrypt_sign(c, false);
+        }
+    }
+
+    fragment_housekeeping(c->c2.fragment, &c->c2.frame_fragment, &c->c2.timeval);
+}
+#endif /* ifdef ENABLE_FRAGMENT */
+
+/*
+ * Buffer reallocation, for use with null encryption.
+ */
+static inline void
+buffer_turnover(const uint8_t *orig_buf, struct buffer *dest_stub, struct buffer *src_stub, struct buffer *storage)
+{
+    if (orig_buf == src_stub->data && src_stub->data != storage->data)
+    {
+        buf_assign(storage, src_stub);
+        *dest_stub = *storage;
+    }
+    else
+    {
+        *dest_stub = *src_stub;
+    }
+}
+
+/*
+ * Compress, fragment, encrypt and HMAC-sign an outgoing packet.
+ * Input: c->c2.buf
+ * Output: c->c2.to_link
+ */
+void
+encrypt_sign(struct context *c, bool comp_frag)
+{
+    struct context_buffers *b = c->c2.buffers;
+    const uint8_t *orig_buf = c->c2.buf.data;
+    struct crypto_options *co = NULL;
+
+#if P2MP_SERVER
+    /*
+     * Drop non-TLS outgoing packet if client-connect script/plugin
+     * has not yet succeeded.
+     */
+    if (c->c2.context_auth != CAS_SUCCEEDED)
+    {
+        c->c2.buf.len = 0;
+    }
+#endif
+
+    if (comp_frag)
+    {
+#ifdef USE_COMP
+        /* Compress the packet. */
+        if (c->c2.comp_context)
+        {
+            (*c->c2.comp_context->alg.compress)(&c->c2.buf, b->compress_buf, c->c2.comp_context, &c->c2.frame);
+        }
+#endif
+#ifdef ENABLE_FRAGMENT
+        if (c->c2.fragment)
+        {
+            fragment_outgoing(c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment);
+        }
+#endif
+    }
+
+#ifdef ENABLE_CRYPTO
+    /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+    ASSERT(buf_init(&b->encrypt_buf, FRAME_HEADROOM(&c->c2.frame)));
+
+    if (c->c2.tls_multi)
+    {
+        /* Get the key we will use to encrypt the packet. */
+        tls_pre_encrypt(c->c2.tls_multi, &c->c2.buf, &co);
+        /* If using P_DATA_V2, prepend the 1-byte opcode and 3-byte peer-id to the
+         * packet before openvpn_encrypt(), so we can authenticate the opcode too.
+         */
+        if (c->c2.buf.len > 0 && c->c2.tls_multi->use_peer_id)
+        {
+            tls_prepend_opcode_v2(c->c2.tls_multi, &b->encrypt_buf);
+        }
+    }
+    else
+    {
+        co = &c->c2.crypto_options;
+    }
+
+    /* Encrypt and authenticate the packet */
+    openvpn_encrypt(&c->c2.buf, b->encrypt_buf, co);
+
+    /* Do packet administration */
+    if (c->c2.tls_multi)
+    {
+        if (c->c2.buf.len > 0 && !c->c2.tls_multi->use_peer_id)
+        {
+            tls_prepend_opcode_v1(c->c2.tls_multi, &c->c2.buf);
+        }
+        tls_post_encrypt(c->c2.tls_multi, &c->c2.buf);
+    }
+#endif /* ifdef ENABLE_CRYPTO */
+
+    /*
+     * Get the address we will be sending the packet to.
+     */
+    link_socket_get_outgoing_addr(&c->c2.buf, get_link_socket_info(c),
+                                  &c->c2.to_link_addr);
+
+    /* if null encryption, copy result to read_tun_buf */
+    buffer_turnover(orig_buf, &c->c2.to_link, &c->c2.buf, &b->read_tun_buf);
+}
+
+/*
+ * Coarse timers work to 1 second resolution.
+ */
+static void
+process_coarse_timers(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    /* flush current packet-id to file once per 60
+     * seconds if --replay-persist was specified */
+    check_packet_id_persist_flush(c);
+#endif
+
+    /* should we update status file? */
+    check_status_file(c);
+
+    /* process connection establishment items */
+    check_connection_established(c);
+
+#if P2MP
+    /* see if we should send a push_request in response to --pull */
+    check_push_request(c);
+#endif
+
+#ifdef PLUGIN_PF
+    pf_check_reload(c);
+#endif
+
+    /* process --route options */
+    check_add_routes(c);
+
+    /* possibly exit due to --inactive */
+    check_inactivity_timeout(c);
+    if (c->sig->signal_received)
+    {
+        return;
+    }
+
+    /* restart if ping not received */
+    check_ping_restart(c);
+    if (c->sig->signal_received)
+    {
+        return;
+    }
+
+#if P2MP
+    if (c->c2.tls_multi)
+    {
+        check_server_poll_timeout(c);
+        if (c->sig->signal_received)
+        {
+            return;
+        }
+
+        check_scheduled_exit(c);
+        if (c->sig->signal_received)
+        {
+            return;
+        }
+    }
+#endif
+
+#ifdef ENABLE_OCC
+    /* Should we send an OCC_REQUEST message? */
+    check_send_occ_req(c);
+
+    /* Should we send an MTU load test? */
+    check_send_occ_load_test(c);
+
+    /* Should we send an OCC_EXIT message to remote? */
+    if (c->c2.explicit_exit_notification_time_wait)
+    {
+        process_explicit_exit_notification_timer_wakeup(c);
+    }
+#endif
+
+    /* Should we ping the remote? */
+    check_ping_send(c);
+}
+
+static void
+check_coarse_timers_dowork(struct context *c)
+{
+    const struct timeval save = c->c2.timeval;
+    c->c2.timeval.tv_sec = BIG_TIMEOUT;
+    c->c2.timeval.tv_usec = 0;
+    process_coarse_timers(c);
+    c->c2.coarse_timer_wakeup = now + c->c2.timeval.tv_sec;
+
+    dmsg(D_INTERVAL, "TIMER: coarse timer wakeup %d seconds", (int) c->c2.timeval.tv_sec);
+
+    /* Is the coarse timeout NOT the earliest one? */
+    if (c->c2.timeval.tv_sec > save.tv_sec)
+    {
+        c->c2.timeval = save;
+    }
+}
+
+static inline void
+check_coarse_timers(struct context *c)
+{
+    const time_t local_now = now;
+    if (local_now >= c->c2.coarse_timer_wakeup)
+    {
+        check_coarse_timers_dowork(c);
+    }
+    else
+    {
+        context_reschedule_sec(c, c->c2.coarse_timer_wakeup - local_now);
+    }
+}
+
+static void
+check_timeout_random_component_dowork(struct context *c)
+{
+    const int update_interval = 10; /* seconds */
+    c->c2.update_timeout_random_component = now + update_interval;
+    c->c2.timeout_random_component.tv_usec = (time_t) get_random() & 0x0003FFFF;
+    c->c2.timeout_random_component.tv_sec = 0;
+
+    dmsg(D_INTERVAL, "RANDOM USEC=%d", (int) c->c2.timeout_random_component.tv_usec);
+}
+
+static inline void
+check_timeout_random_component(struct context *c)
+{
+    if (now >= c->c2.update_timeout_random_component)
+    {
+        check_timeout_random_component_dowork(c);
+    }
+    if (c->c2.timeval.tv_sec >= 1)
+    {
+        tv_add(&c->c2.timeval, &c->c2.timeout_random_component);
+    }
+}
+
+/*
+ * Handle addition and removal of the 10-byte Socks5 header
+ * in UDP packets.
+ */
+
+static inline void
+socks_postprocess_incoming_link(struct context *c)
+{
+    if (c->c2.link_socket->socks_proxy && c->c2.link_socket->info.proto == PROTO_UDP)
+    {
+        socks_process_incoming_udp(&c->c2.buf, &c->c2.from);
+    }
+}
+
+static inline void
+socks_preprocess_outgoing_link(struct context *c,
+                               struct link_socket_actual **to_addr,
+                               int *size_delta)
+{
+    if (c->c2.link_socket->socks_proxy && c->c2.link_socket->info.proto == PROTO_UDP)
+    {
+        *size_delta += socks_process_outgoing_udp(&c->c2.to_link, c->c2.to_link_addr);
+        *to_addr = &c->c2.link_socket->socks_relay;
+    }
+}
+
+/* undo effect of socks_preprocess_outgoing_link */
+static inline void
+link_socket_write_post_size_adjust(int *size,
+                                   int size_delta,
+                                   struct buffer *buf)
+{
+    if (size_delta > 0 && *size > size_delta)
+    {
+        *size -= size_delta;
+        if (!buf_advance(buf, size_delta))
+        {
+            *size = 0;
+        }
+    }
+}
+
+/*
+ * Output: c->c2.buf
+ */
+
+void
+read_incoming_link(struct context *c)
+{
+    /*
+     * Set up for recvfrom call to read datagram
+     * sent to our TCP/UDP port.
+     */
+    int status;
+
+    /*ASSERT (!c->c2.to_tun.len);*/
+
+    perf_push(PERF_READ_IN_LINK);
+
+    c->c2.buf = c->c2.buffers->read_link_buf;
+    ASSERT(buf_init(&c->c2.buf, FRAME_HEADROOM_ADJ(&c->c2.frame, FRAME_HEADROOM_MARKER_READ_LINK)));
+
+    status = link_socket_read(c->c2.link_socket,
+                              &c->c2.buf,
+                              &c->c2.from);
+
+    if (socket_connection_reset(c->c2.link_socket, status))
+    {
+#if PORT_SHARE
+        if (port_share && socket_foreign_protocol_detected(c->c2.link_socket))
+        {
+            const struct buffer *fbuf = socket_foreign_protocol_head(c->c2.link_socket);
+            const int sd = socket_foreign_protocol_sd(c->c2.link_socket);
+            port_share_redirect(port_share, fbuf, sd);
+            register_signal(c, SIGTERM, "port-share-redirect");
+        }
+        else
+#endif
+        {
+            /* received a disconnect from a connection-oriented protocol */
+            if (c->options.inetd)
+            {
+                register_signal(c, SIGTERM, "connection-reset-inetd");
+                msg(D_STREAM_ERRORS, "Connection reset, inetd/xinetd exit [%d]", status);
+            }
+            else
+            {
+#ifdef ENABLE_OCC
+                if (event_timeout_defined(&c->c2.explicit_exit_notification_interval))
+                {
+                    msg(D_STREAM_ERRORS, "Connection reset during exit notification period, ignoring [%d]", status);
+                    management_sleep(1);
+                }
+                else
+#endif
+                {
+                    register_signal(c, SIGUSR1, "connection-reset"); /* SOFT-SIGUSR1 -- TCP connection reset */
+                    msg(D_STREAM_ERRORS, "Connection reset, restarting [%d]", status);
+                }
+            }
+        }
+        perf_pop();
+        return;
+    }
+
+    /* check recvfrom status */
+    check_status(status, "read", c->c2.link_socket, NULL);
+
+    /* Remove socks header if applicable */
+    socks_postprocess_incoming_link(c);
+
+    perf_pop();
+}
+
+bool
+process_incoming_link_part1(struct context *c, struct link_socket_info *lsi, bool floated)
+{
+    struct gc_arena gc = gc_new();
+    bool decrypt_status = false;
+
+    if (c->c2.buf.len > 0)
+    {
+        c->c2.link_read_bytes += c->c2.buf.len;
+        link_read_bytes_global += c->c2.buf.len;
+#ifdef ENABLE_MEMSTATS
+        if (mmap_stats)
+        {
+            mmap_stats->link_read_bytes = link_read_bytes_global;
+        }
+#endif
+        c->c2.original_recv_size = c->c2.buf.len;
+#ifdef ENABLE_MANAGEMENT
+        if (management)
+        {
+            management_bytes_in(management, c->c2.buf.len);
+#ifdef MANAGEMENT_DEF_AUTH
+            management_bytes_server(management, &c->c2.link_read_bytes, &c->c2.link_write_bytes, &c->c2.mda_context);
+#endif
+        }
+#endif
+    }
+    else
+    {
+        c->c2.original_recv_size = 0;
+    }
+
+#ifdef ENABLE_DEBUG
+    /* take action to corrupt packet if we are in gremlin test mode */
+    if (c->options.gremlin)
+    {
+        if (!ask_gremlin(c->options.gremlin))
+        {
+            c->c2.buf.len = 0;
+        }
+        corrupt_gremlin(&c->c2.buf, c->options.gremlin);
+    }
+#endif
+
+    /* log incoming packet */
+#ifdef LOG_RW
+    if (c->c2.log_rw && c->c2.buf.len > 0)
+    {
+        fprintf(stderr, "R");
+    }
+#endif
+    msg(D_LINK_RW, "%s READ [%d] from %s: %s",
+        proto2ascii(lsi->proto, lsi->af, true),
+        BLEN(&c->c2.buf),
+        print_link_socket_actual(&c->c2.from, &gc),
+        PROTO_DUMP(&c->c2.buf, &gc));
+
+    /*
+     * Good, non-zero length packet received.
+     * Commence multi-stage processing of packet,
+     * such as authenticate, decrypt, decompress.
+     * If any stage fails, it sets buf.len to 0 or -1,
+     * telling downstream stages to ignore the packet.
+     */
+    if (c->c2.buf.len > 0)
+    {
+        struct crypto_options *co = NULL;
+        const uint8_t *ad_start = NULL;
+        if (!link_socket_verify_incoming_addr(&c->c2.buf, lsi, &c->c2.from))
+        {
+            link_socket_bad_incoming_addr(&c->c2.buf, lsi, &c->c2.from);
+        }
+
+#ifdef ENABLE_CRYPTO
+        if (c->c2.tls_multi)
+        {
+            /*
+             * If tls_pre_decrypt returns true, it means the incoming
+             * packet was a good TLS control channel packet.  If so, TLS code
+             * will deal with the packet and set buf.len to 0 so downstream
+             * stages ignore it.
+             *
+             * If the packet is a data channel packet, tls_pre_decrypt
+             * will load crypto_options with the correct encryption key
+             * and return false.
+             */
+            uint8_t opcode = *BPTR(&c->c2.buf) >> P_OPCODE_SHIFT;
+            if (tls_pre_decrypt(c->c2.tls_multi, &c->c2.from, &c->c2.buf, &co,
+                                floated, &ad_start))
+            {
+                /* Restore pre-NCP frame parameters */
+                if (is_hard_reset(opcode, c->options.key_method))
+                {
+                    c->c2.frame = c->c2.frame_initial;
+#ifdef ENABLE_FRAGMENT
+                    c->c2.frame_fragment = c->c2.frame_fragment_initial;
+#endif
+                }
+
+                interval_action(&c->c2.tmp_int);
+
+                /* reset packet received timer if TLS packet */
+                if (c->options.ping_rec_timeout)
+                {
+                    event_timeout_reset(&c->c2.ping_rec_interval);
+                }
+            }
+        }
+        else
+        {
+            co = &c->c2.crypto_options;
+        }
+#if P2MP_SERVER
+        /*
+         * Drop non-TLS packet if client-connect script/plugin has not
+         * yet succeeded.
+         */
+        if (c->c2.context_auth != CAS_SUCCEEDED)
+        {
+            c->c2.buf.len = 0;
+        }
+#endif
+
+        /* authenticate and decrypt the incoming packet */
+        decrypt_status = openvpn_decrypt(&c->c2.buf, c->c2.buffers->decrypt_buf,
+                                         co, &c->c2.frame, ad_start);
+
+        if (!decrypt_status && link_socket_connection_oriented(c->c2.link_socket))
+        {
+            /* decryption errors are fatal in TCP mode */
+            register_signal(c, SIGUSR1, "decryption-error"); /* SOFT-SIGUSR1 -- decryption error in TCP mode */
+            msg(D_STREAM_ERRORS, "Fatal decryption error (process_incoming_link), restarting");
+        }
+#else /* ENABLE_CRYPTO */
+        decrypt_status = true;
+#endif /* ENABLE_CRYPTO */
+    }
+    else
+    {
+        buf_reset(&c->c2.to_tun);
+    }
+    gc_free(&gc);
+
+    return decrypt_status;
+}
+
+void
+process_incoming_link_part2(struct context *c, struct link_socket_info *lsi, const uint8_t *orig_buf)
+{
+    if (c->c2.buf.len > 0)
+    {
+#ifdef ENABLE_FRAGMENT
+        if (c->c2.fragment)
+        {
+            fragment_incoming(c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment);
+        }
+#endif
+
+#ifdef USE_COMP
+        /* decompress the incoming packet */
+        if (c->c2.comp_context)
+        {
+            (*c->c2.comp_context->alg.decompress)(&c->c2.buf, c->c2.buffers->decompress_buf, c->c2.comp_context, &c->c2.frame);
+        }
+#endif
+
+#ifdef PACKET_TRUNCATION_CHECK
+        /* if (c->c2.buf.len > 1) --c->c2.buf.len; */
+        ipv4_packet_size_verify(BPTR(&c->c2.buf),
+                                BLEN(&c->c2.buf),
+                                TUNNEL_TYPE(c->c1.tuntap),
+                                "POST_DECRYPT",
+                                &c->c2.n_trunc_post_decrypt);
+#endif
+
+        /*
+         * Set our "official" outgoing address, since
+         * if buf.len is non-zero, we know the packet
+         * authenticated.  In TLS mode we do nothing
+         * because TLS mode takes care of source address
+         * authentication.
+         *
+         * Also, update the persisted version of our packet-id.
+         */
+        if (!TLS_MODE(c))
+        {
+            link_socket_set_outgoing_addr(&c->c2.buf, lsi, &c->c2.from, NULL, c->c2.es);
+        }
+
+        /* reset packet received timer */
+        if (c->options.ping_rec_timeout && c->c2.buf.len > 0)
+        {
+            event_timeout_reset(&c->c2.ping_rec_interval);
+        }
+
+        /* increment authenticated receive byte count */
+        if (c->c2.buf.len > 0)
+        {
+            c->c2.link_read_bytes_auth += c->c2.buf.len;
+            c->c2.max_recv_size_local = max_int(c->c2.original_recv_size, c->c2.max_recv_size_local);
+        }
+
+        /* Did we just receive an openvpn ping packet? */
+        if (is_ping_msg(&c->c2.buf))
+        {
+            dmsg(D_PING, "RECEIVED PING PACKET");
+            c->c2.buf.len = 0; /* drop packet */
+        }
+
+#ifdef ENABLE_OCC
+        /* Did we just receive an OCC packet? */
+        if (is_occ_msg(&c->c2.buf))
+        {
+            process_received_occ_msg(c);
+        }
+#endif
+
+        buffer_turnover(orig_buf, &c->c2.to_tun, &c->c2.buf, &c->c2.buffers->read_link_buf);
+
+        /* to_tun defined + unopened tuntap can cause deadlock */
+        if (!tuntap_defined(c->c1.tuntap))
+        {
+            c->c2.to_tun.len = 0;
+        }
+    }
+    else
+    {
+        buf_reset(&c->c2.to_tun);
+    }
+}
+
+static void
+process_incoming_link(struct context *c)
+{
+    perf_push(PERF_PROC_IN_LINK);
+
+    struct link_socket_info *lsi = get_link_socket_info(c);
+    const uint8_t *orig_buf = c->c2.buf.data;
+
+    process_incoming_link_part1(c, lsi, false);
+    process_incoming_link_part2(c, lsi, orig_buf);
+
+    perf_pop();
+}
+
+/*
+ * Output: c->c2.buf
+ */
+
+void
+read_incoming_tun(struct context *c)
+{
+    /*
+     * Setup for read() call on TUN/TAP device.
+     */
+    /*ASSERT (!c->c2.to_link.len);*/
+
+    perf_push(PERF_READ_IN_TUN);
+
+    c->c2.buf = c->c2.buffers->read_tun_buf;
+#ifdef TUN_PASS_BUFFER
+    read_tun_buffered(c->c1.tuntap, &c->c2.buf);
+#else
+    ASSERT(buf_init(&c->c2.buf, FRAME_HEADROOM(&c->c2.frame)));
+    ASSERT(buf_safe(&c->c2.buf, MAX_RW_SIZE_TUN(&c->c2.frame)));
+    c->c2.buf.len = read_tun(c->c1.tuntap, BPTR(&c->c2.buf), MAX_RW_SIZE_TUN(&c->c2.frame));
+#endif
+
+#ifdef PACKET_TRUNCATION_CHECK
+    ipv4_packet_size_verify(BPTR(&c->c2.buf),
+                            BLEN(&c->c2.buf),
+                            TUNNEL_TYPE(c->c1.tuntap),
+                            "READ_TUN",
+                            &c->c2.n_trunc_tun_read);
+#endif
+
+    /* Was TUN/TAP interface stopped? */
+    if (tuntap_stop(c->c2.buf.len))
+    {
+        register_signal(c, SIGTERM, "tun-stop");
+        msg(M_INFO, "TUN/TAP interface has been stopped, exiting");
+        perf_pop();
+        return;
+    }
+
+    /* Was TUN/TAP I/O operation aborted? */
+    if (tuntap_abort(c->c2.buf.len))
+    {
+        register_signal(c, SIGHUP, "tun-abort");
+        c->persist.restart_sleep_seconds = 10;
+        msg(M_INFO, "TUN/TAP I/O operation aborted, restarting");
+        perf_pop();
+        return;
+    }
+
+    /* Check the status return from read() */
+    check_status(c->c2.buf.len, "read from TUN/TAP", NULL, c->c1.tuntap);
+
+    perf_pop();
+}
+
+/**
+ * Drops UDP packets which OS decided to route via tun.
+ *
+ * On Windows and OS X when netwotk adapter is disabled or
+ * disconnected, platform starts to use tun as external interface.
+ * When packet is sent to tun, it comes to openvpn, encapsulated
+ * and sent to routing table, which sends it again to tun.
+ */
+static void
+drop_if_recursive_routing(struct context *c, struct buffer *buf)
+{
+    bool drop = false;
+    struct openvpn_sockaddr tun_sa;
+    int ip_hdr_offset = 0;
+
+    if (c->c2.to_link_addr == NULL) /* no remote addr known */
+    {
+        return;
+    }
+
+    tun_sa = c->c2.to_link_addr->dest;
+
+    int proto_ver = get_tun_ip_ver(TUNNEL_TYPE(c->c1.tuntap), &c->c2.buf, &ip_hdr_offset);
+
+    if (proto_ver == 4)
+    {
+        const struct openvpn_iphdr *pip;
+
+        /* make sure we got whole IP header */
+        if (BLEN(buf) < ((int) sizeof(struct openvpn_iphdr) + ip_hdr_offset))
+        {
+            return;
+        }
+
+        /* skip ipv4 packets for ipv6 tun */
+        if (tun_sa.addr.sa.sa_family != AF_INET)
+        {
+            return;
+        }
+
+        pip = (struct openvpn_iphdr *) (BPTR(buf) + ip_hdr_offset);
+
+        /* drop packets with same dest addr as gateway */
+        if (tun_sa.addr.in4.sin_addr.s_addr == pip->daddr)
+        {
+            drop = true;
+        }
+    }
+    else if (proto_ver == 6)
+    {
+        const struct openvpn_ipv6hdr *pip6;
+
+        /* make sure we got whole IPv6 header */
+        if (BLEN(buf) < ((int) sizeof(struct openvpn_ipv6hdr) + ip_hdr_offset))
+        {
+            return;
+        }
+
+        /* skip ipv6 packets for ipv4 tun */
+        if (tun_sa.addr.sa.sa_family != AF_INET6)
+        {
+            return;
+        }
+
+        /* drop packets with same dest addr as gateway */
+        pip6 = (struct openvpn_ipv6hdr *) (BPTR(buf) + ip_hdr_offset);
+        if (IN6_ARE_ADDR_EQUAL(&tun_sa.addr.in6.sin6_addr, &pip6->daddr))
+        {
+            drop = true;
+        }
+    }
+
+    if (drop)
+    {
+        struct gc_arena gc = gc_new();
+
+        c->c2.buf.len = 0;
+
+        msg(D_LOW, "Recursive routing detected, drop tun packet to %s",
+            print_link_socket_actual(c->c2.to_link_addr, &gc));
+        gc_free(&gc);
+    }
+}
+
+/*
+ * Input:  c->c2.buf
+ * Output: c->c2.to_link
+ */
+
+void
+process_incoming_tun(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+
+    perf_push(PERF_PROC_IN_TUN);
+
+    if (c->c2.buf.len > 0)
+    {
+        c->c2.tun_read_bytes += c->c2.buf.len;
+    }
+
+#ifdef LOG_RW
+    if (c->c2.log_rw && c->c2.buf.len > 0)
+    {
+        fprintf(stderr, "r");
+    }
+#endif
+
+    /* Show packet content */
+    dmsg(D_TUN_RW, "TUN READ [%d]", BLEN(&c->c2.buf));
+
+    if (c->c2.buf.len > 0)
+    {
+        if ((c->options.mode == MODE_POINT_TO_POINT) && (!c->options.allow_recursive_routing))
+        {
+            drop_if_recursive_routing(c, &c->c2.buf);
+        }
+        /*
+         * The --passtos and --mssfix options require
+         * us to examine the IP header (IPv4 or IPv6).
+         */
+        process_ip_header(c, PIPV4_PASSTOS|PIP_MSSFIX|PIPV4_CLIENT_NAT, &c->c2.buf);
+
+#ifdef PACKET_TRUNCATION_CHECK
+        /* if (c->c2.buf.len > 1) --c->c2.buf.len; */
+        ipv4_packet_size_verify(BPTR(&c->c2.buf),
+                                BLEN(&c->c2.buf),
+                                TUNNEL_TYPE(c->c1.tuntap),
+                                "PRE_ENCRYPT",
+                                &c->c2.n_trunc_pre_encrypt);
+#endif
+
+        encrypt_sign(c, true);
+    }
+    else
+    {
+        buf_reset(&c->c2.to_link);
+    }
+    perf_pop();
+    gc_free(&gc);
+}
+
+void
+process_ip_header(struct context *c, unsigned int flags, struct buffer *buf)
+{
+    if (!c->options.ce.mssfix)
+    {
+        flags &= ~PIP_MSSFIX;
+    }
+#if PASSTOS_CAPABILITY
+    if (!c->options.passtos)
+    {
+        flags &= ~PIPV4_PASSTOS;
+    }
+#endif
+    if (!c->options.client_nat)
+    {
+        flags &= ~PIPV4_CLIENT_NAT;
+    }
+    if (!c->options.route_gateway_via_dhcp)
+    {
+        flags &= ~PIPV4_EXTRACT_DHCP_ROUTER;
+    }
+
+    if (buf->len > 0)
+    {
+        /*
+         * The --passtos and --mssfix options require
+         * us to examine the IPv4 header.
+         */
+
+        if (flags & (PIP_MSSFIX
+#if PASSTOS_CAPABILITY
+                     | PIPV4_PASSTOS
+#endif
+                     | PIPV4_CLIENT_NAT
+                     ))
+        {
+            struct buffer ipbuf = *buf;
+            if (is_ipv4(TUNNEL_TYPE(c->c1.tuntap), &ipbuf))
+            {
+#if PASSTOS_CAPABILITY
+                /* extract TOS from IP header */
+                if (flags & PIPV4_PASSTOS)
+                {
+                    link_socket_extract_tos(c->c2.link_socket, &ipbuf);
+                }
+#endif
+
+                /* possibly alter the TCP MSS */
+                if (flags & PIP_MSSFIX)
+                {
+                    mss_fixup_ipv4(&ipbuf, MTU_TO_MSS(TUN_MTU_SIZE_DYNAMIC(&c->c2.frame)));
+                }
+
+                /* possibly do NAT on packet */
+                if ((flags & PIPV4_CLIENT_NAT) && c->options.client_nat)
+                {
+                    const int direction = (flags & PIPV4_OUTGOING) ? CN_INCOMING : CN_OUTGOING;
+                    client_nat_transform(c->options.client_nat, &ipbuf, direction);
+                }
+                /* possibly extract a DHCP router message */
+                if (flags & PIPV4_EXTRACT_DHCP_ROUTER)
+                {
+                    const in_addr_t dhcp_router = dhcp_extract_router_msg(&ipbuf);
+                    if (dhcp_router)
+                    {
+                        route_list_add_vpn_gateway(c->c1.route_list, c->c2.es, dhcp_router);
+                    }
+                }
+            }
+            else if (is_ipv6(TUNNEL_TYPE(c->c1.tuntap), &ipbuf))
+            {
+                /* possibly alter the TCP MSS */
+                if (flags & PIP_MSSFIX)
+                {
+                    mss_fixup_ipv6(&ipbuf, MTU_TO_MSS(TUN_MTU_SIZE_DYNAMIC(&c->c2.frame)));
+                }
+            }
+        }
+    }
+}
+
+/*
+ * Input: c->c2.to_link
+ */
+
+void
+process_outgoing_link(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+    int error_code = 0;
+
+    perf_push(PERF_PROC_OUT_LINK);
+
+    if (c->c2.to_link.len > 0 && c->c2.to_link.len <= EXPANDED_SIZE(&c->c2.frame))
+    {
+        /*
+         * Setup for call to send/sendto which will send
+         * packet to remote over the TCP/UDP port.
+         */
+        int size = 0;
+        ASSERT(link_socket_actual_defined(c->c2.to_link_addr));
+
+#ifdef ENABLE_DEBUG
+        /* In gremlin-test mode, we may choose to drop this packet */
+        if (!c->options.gremlin || ask_gremlin(c->options.gremlin))
+#endif
+        {
+            /*
+             * Let the traffic shaper know how many bytes
+             * we wrote.
+             */
+#ifdef ENABLE_FEATURE_SHAPER
+            if (c->options.shaper)
+            {
+                shaper_wrote_bytes(&c->c2.shaper, BLEN(&c->c2.to_link)
+                                   + datagram_overhead(c->options.ce.proto));
+            }
+#endif
+            /*
+             * Let the pinger know that we sent a packet.
+             */
+            if (c->options.ping_send_timeout)
+            {
+                event_timeout_reset(&c->c2.ping_send_interval);
+            }
+
+#if PASSTOS_CAPABILITY
+            /* Set TOS */
+            link_socket_set_tos(c->c2.link_socket);
+#endif
+
+            /* Log packet send */
+#ifdef LOG_RW
+            if (c->c2.log_rw)
+            {
+                fprintf(stderr, "W");
+            }
+#endif
+            msg(D_LINK_RW, "%s WRITE [%d] to %s: %s",
+                proto2ascii(c->c2.link_socket->info.proto, c->c2.link_socket->info.af, true),
+                BLEN(&c->c2.to_link),
+                print_link_socket_actual(c->c2.to_link_addr, &gc),
+                PROTO_DUMP(&c->c2.to_link, &gc));
+
+            /* Packet send complexified by possible Socks5 usage */
+            {
+                struct link_socket_actual *to_addr = c->c2.to_link_addr;
+                int size_delta = 0;
+
+                /* If Socks5 over UDP, prepend header */
+                socks_preprocess_outgoing_link(c, &to_addr, &size_delta);
+
+                /* Send packet */
+                size = link_socket_write(c->c2.link_socket,
+                                         &c->c2.to_link,
+                                         to_addr);
+
+                /* Undo effect of prepend */
+                link_socket_write_post_size_adjust(&size, size_delta, &c->c2.to_link);
+            }
+
+            if (size > 0)
+            {
+                c->c2.max_send_size_local = max_int(size, c->c2.max_send_size_local);
+                c->c2.link_write_bytes += size;
+                link_write_bytes_global += size;
+#ifdef ENABLE_MEMSTATS
+                if (mmap_stats)
+                {
+                    mmap_stats->link_write_bytes = link_write_bytes_global;
+                }
+#endif
+#ifdef ENABLE_MANAGEMENT
+                if (management)
+                {
+                    management_bytes_out(management, size);
+#ifdef MANAGEMENT_DEF_AUTH
+                    management_bytes_server(management, &c->c2.link_read_bytes, &c->c2.link_write_bytes, &c->c2.mda_context);
+#endif
+                }
+#endif
+            }
+        }
+
+        /* Check return status */
+        error_code = openvpn_errno();
+        check_status(size, "write", c->c2.link_socket, NULL);
+
+        if (size > 0)
+        {
+            /* Did we write a different size packet than we intended? */
+            if (size != BLEN(&c->c2.to_link))
+            {
+                msg(D_LINK_ERRORS,
+                    "TCP/UDP packet was truncated/expanded on write to %s (tried=%d,actual=%d)",
+                    print_link_socket_actual(c->c2.to_link_addr, &gc),
+                    BLEN(&c->c2.to_link),
+                    size);
+            }
+        }
+
+        /* if not a ping/control message, indicate activity regarding --inactive parameter */
+        if (c->c2.buf.len > 0)
+        {
+            register_activity(c, size);
+        }
+
+
+#ifdef ENABLE_CRYPTO
+        /* for unreachable network and "connecting" state switch to the next host */
+        if (size < 0 && ENETUNREACH == error_code && c->c2.tls_multi
+            && !tls_initial_packet_received(c->c2.tls_multi) && c->options.mode == MODE_POINT_TO_POINT)
+        {
+            msg(M_INFO, "Network unreachable, restarting");
+            register_signal(c, SIGUSR1, "network-unreachable");
+        }
+#endif
+    }
+    else
+    {
+        if (c->c2.to_link.len > 0)
+        {
+            msg(D_LINK_ERRORS, "TCP/UDP packet too large on write to %s (tried=%d,max=%d)",
+                print_link_socket_actual(c->c2.to_link_addr, &gc),
+                c->c2.to_link.len,
+                EXPANDED_SIZE(&c->c2.frame));
+        }
+    }
+
+    buf_reset(&c->c2.to_link);
+
+    perf_pop();
+    gc_free(&gc);
+}
+
+/*
+ * Input: c->c2.to_tun
+ */
+
+void
+process_outgoing_tun(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+
+    /*
+     * Set up for write() call to TUN/TAP
+     * device.
+     */
+    if (c->c2.to_tun.len <= 0)
+    {
+        return;
+    }
+
+    perf_push(PERF_PROC_OUT_TUN);
+
+    /*
+     * The --mssfix option requires
+     * us to examine the IP header (IPv4 or IPv6).
+     */
+    process_ip_header(c, PIP_MSSFIX|PIPV4_EXTRACT_DHCP_ROUTER|PIPV4_CLIENT_NAT|PIPV4_OUTGOING, &c->c2.to_tun);
+
+    if (c->c2.to_tun.len <= MAX_RW_SIZE_TUN(&c->c2.frame))
+    {
+        /*
+         * Write to TUN/TAP device.
+         */
+        int size;
+
+#ifdef LOG_RW
+        if (c->c2.log_rw)
+        {
+            fprintf(stderr, "w");
+        }
+#endif
+        dmsg(D_TUN_RW, "TUN WRITE [%d]", BLEN(&c->c2.to_tun));
+
+#ifdef PACKET_TRUNCATION_CHECK
+        ipv4_packet_size_verify(BPTR(&c->c2.to_tun),
+                                BLEN(&c->c2.to_tun),
+                                TUNNEL_TYPE(c->c1.tuntap),
+                                "WRITE_TUN",
+                                &c->c2.n_trunc_tun_write);
+#endif
+
+#ifdef TUN_PASS_BUFFER
+        size = write_tun_buffered(c->c1.tuntap, &c->c2.to_tun);
+#else
+        size = write_tun(c->c1.tuntap, BPTR(&c->c2.to_tun), BLEN(&c->c2.to_tun));
+#endif
+
+        if (size > 0)
+        {
+            c->c2.tun_write_bytes += size;
+        }
+        check_status(size, "write to TUN/TAP", NULL, c->c1.tuntap);
+
+        /* check written packet size */
+        if (size > 0)
+        {
+            /* Did we write a different size packet than we intended? */
+            if (size != BLEN(&c->c2.to_tun))
+            {
+                msg(D_LINK_ERRORS,
+                    "TUN/TAP packet was destructively fragmented on write to %s (tried=%d,actual=%d)",
+                    c->c1.tuntap->actual_name,
+                    BLEN(&c->c2.to_tun),
+                    size);
+            }
+
+            /* indicate activity regarding --inactive parameter */
+            register_activity(c, size);
+        }
+    }
+    else
+    {
+        /*
+         * This should never happen, probably indicates some kind
+         * of MTU mismatch.
+         */
+        msg(D_LINK_ERRORS, "tun packet too large on write (tried=%d,max=%d)",
+            c->c2.to_tun.len,
+            MAX_RW_SIZE_TUN(&c->c2.frame));
+    }
+
+    buf_reset(&c->c2.to_tun);
+
+    perf_pop();
+    gc_free(&gc);
+}
+
+void
+pre_select(struct context *c)
+{
+    /* make sure current time (now) is updated on function entry */
+
+    /*
+     * Start with an effectively infinite timeout, then let it
+     * reduce to a timeout that reflects the component which
+     * needs the earliest service.
+     */
+    c->c2.timeval.tv_sec = BIG_TIMEOUT;
+    c->c2.timeval.tv_usec = 0;
+
+#if defined(_WIN32)
+    if (check_debug_level(D_TAP_WIN_DEBUG))
+    {
+        c->c2.timeval.tv_sec = 1;
+        if (tuntap_defined(c->c1.tuntap))
+        {
+            tun_show_debug(c->c1.tuntap);
+        }
+    }
+#endif
+
+    /* check coarse timers? */
+    check_coarse_timers(c);
+    if (c->sig->signal_received)
+    {
+        return;
+    }
+
+    /* Does TLS need service? */
+    check_tls(c);
+
+    /* In certain cases, TLS errors will require a restart */
+    check_tls_errors(c);
+    if (c->sig->signal_received)
+    {
+        return;
+    }
+
+    /* check for incoming configuration info on the control channel */
+    check_incoming_control_channel(c);
+
+#ifdef ENABLE_OCC
+    /* Should we send an OCC message? */
+    check_send_occ_msg(c);
+#endif
+
+#ifdef ENABLE_FRAGMENT
+    /* Should we deliver a datagram fragment to remote? */
+    check_fragment(c);
+#endif
+
+    /* Update random component of timeout */
+    check_timeout_random_component(c);
+}
+
+/*
+ * Wait for I/O events.  Used for both TCP & UDP sockets
+ * in point-to-point mode and for UDP sockets in
+ * point-to-multipoint mode.
+ */
+
+void
+io_wait_dowork(struct context *c, const unsigned int flags)
+{
+    unsigned int socket = 0;
+    unsigned int tuntap = 0;
+    struct event_set_return esr[4];
+
+    /* These shifts all depend on EVENT_READ and EVENT_WRITE */
+    static int socket_shift = 0;   /* depends on SOCKET_READ and SOCKET_WRITE */
+    static int tun_shift = 2;      /* depends on TUN_READ and TUN_WRITE */
+    static int err_shift = 4;      /* depends on ES_ERROR */
+#ifdef ENABLE_MANAGEMENT
+    static int management_shift = 6; /* depends on MANAGEMENT_READ and MANAGEMENT_WRITE */
+#endif
+#ifdef ENABLE_ASYNC_PUSH
+    static int file_shift = 8;     /* listening inotify events */
+#endif
+
+    /*
+     * Decide what kind of events we want to wait for.
+     */
+    event_reset(c->c2.event_set);
+
+    /*
+     * On win32 we use the keyboard or an event object as a source
+     * of asynchronous signals.
+     */
+    if (flags & IOW_WAIT_SIGNAL)
+    {
+        wait_signal(c->c2.event_set, (void *)&err_shift);
+    }
+
+    /*
+     * If outgoing data (for TCP/UDP port) pending, wait for ready-to-send
+     * status from TCP/UDP port. Otherwise, wait for incoming data on
+     * TUN/TAP device.
+     */
+    if (flags & IOW_TO_LINK)
+    {
+        if (flags & IOW_SHAPER)
+        {
+            /*
+             * If sending this packet would put us over our traffic shaping
+             * quota, don't send -- instead compute the delay we must wait
+             * until it will be OK to send the packet.
+             */
+#ifdef ENABLE_FEATURE_SHAPER
+            int delay = 0;
+
+            /* set traffic shaping delay in microseconds */
+            if (c->options.shaper)
+            {
+                delay = max_int(delay, shaper_delay(&c->c2.shaper));
+            }
+
+            if (delay < 1000)
+            {
+                socket |= EVENT_WRITE;
+            }
+            else
+            {
+                shaper_soonest_event(&c->c2.timeval, delay);
+            }
+#else /* ENABLE_FEATURE_SHAPER */
+            socket |= EVENT_WRITE;
+#endif /* ENABLE_FEATURE_SHAPER */
+        }
+        else
+        {
+            socket |= EVENT_WRITE;
+        }
+    }
+    else if (!((flags & IOW_FRAG) && TO_LINK_FRAG(c)))
+    {
+        if (flags & IOW_READ_TUN)
+        {
+            tuntap |= EVENT_READ;
+        }
+    }
+
+    /*
+     * If outgoing data (for TUN/TAP device) pending, wait for ready-to-send status
+     * from device.  Otherwise, wait for incoming data on TCP/UDP port.
+     */
+    if (flags & IOW_TO_TUN)
+    {
+        tuntap |= EVENT_WRITE;
+    }
+    else
+    {
+        if (flags & IOW_READ_LINK)
+        {
+            socket |= EVENT_READ;
+        }
+    }
+
+    /*
+     * outgoing bcast buffer waiting to be sent?
+     */
+    if (flags & IOW_MBUF)
+    {
+        socket |= EVENT_WRITE;
+    }
+
+    /*
+     * Force wait on TUN input, even if also waiting on TCP/UDP output
+     */
+    if (flags & IOW_READ_TUN_FORCE)
+    {
+        tuntap |= EVENT_READ;
+    }
+
+    /*
+     * Configure event wait based on socket, tuntap flags.
+     */
+    socket_set(c->c2.link_socket, c->c2.event_set, socket, (void *)&socket_shift, NULL);
+    tun_set(c->c1.tuntap, c->c2.event_set, tuntap, (void *)&tun_shift, NULL);
+
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        management_socket_set(management, c->c2.event_set, (void *)&management_shift, NULL);
+    }
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+    /* arm inotify watcher */
+    if (c->options.mode == MODE_SERVER)
+    {
+        event_ctl(c->c2.event_set, c->c2.inotify_fd, EVENT_READ, (void *)&file_shift);
+    }
+#endif
+
+    /*
+     * Possible scenarios:
+     *  (1) tcp/udp port has data available to read
+     *  (2) tcp/udp port is ready to accept more data to write
+     *  (3) tun dev has data available to read
+     *  (4) tun dev is ready to accept more data to write
+     *  (5) we received a signal (handler sets signal_received)
+     *  (6) timeout (tv) expired
+     */
+
+    c->c2.event_set_status = ES_ERROR;
+
+    if (!c->sig->signal_received)
+    {
+        if (!(flags & IOW_CHECK_RESIDUAL) || !socket_read_residual(c->c2.link_socket))
+        {
+            int status;
+
+#ifdef ENABLE_DEBUG
+            if (check_debug_level(D_EVENT_WAIT))
+            {
+                show_wait_status(c);
+            }
+#endif
+
+            /*
+             * Wait for something to happen.
+             */
+            status = event_wait(c->c2.event_set, &c->c2.timeval, esr, SIZE(esr));
+
+            check_status(status, "event_wait", NULL, NULL);
+
+            if (status > 0)
+            {
+                int i;
+                c->c2.event_set_status = 0;
+                for (i = 0; i < status; ++i)
+                {
+                    const struct event_set_return *e = &esr[i];
+                    c->c2.event_set_status |= ((e->rwflags & 3) << *((int *)e->arg));
+                }
+            }
+            else if (status == 0)
+            {
+                c->c2.event_set_status = ES_TIMEOUT;
+            }
+        }
+        else
+        {
+            c->c2.event_set_status = SOCKET_READ;
+        }
+    }
+
+    /* 'now' should always be a reasonably up-to-date timestamp */
+    update_time();
+
+    /* set signal_received if a signal was received */
+    if (c->c2.event_set_status & ES_ERROR)
+    {
+        get_signal(&c->sig->signal_received);
+    }
+
+    dmsg(D_EVENT_WAIT, "I/O WAIT status=0x%04x", c->c2.event_set_status);
+}
+
+void
+process_io(struct context *c)
+{
+    const unsigned int status = c->c2.event_set_status;
+
+#ifdef ENABLE_MANAGEMENT
+    if (status & (MANAGEMENT_READ|MANAGEMENT_WRITE))
+    {
+        ASSERT(management);
+        management_io(management);
+    }
+#endif
+
+    /* TCP/UDP port ready to accept write */
+    if (status & SOCKET_WRITE)
+    {
+        process_outgoing_link(c);
+    }
+    /* TUN device ready to accept write */
+    else if (status & TUN_WRITE)
+    {
+        process_outgoing_tun(c);
+    }
+    /* Incoming data on TCP/UDP port */
+    else if (status & SOCKET_READ)
+    {
+        read_incoming_link(c);
+        if (!IS_SIG(c))
+        {
+            process_incoming_link(c);
+        }
+    }
+    /* Incoming data on TUN device */
+    else if (status & TUN_READ)
+    {
+        read_incoming_tun(c);
+        if (!IS_SIG(c))
+        {
+            process_incoming_tun(c);
+        }
+    }
+}
diff --git a/src/openvpn/forward.h b/src/openvpn/forward.h
new file mode 100644
index 0000000..924cc5e
--- /dev/null
+++ b/src/openvpn/forward.h
@@ -0,0 +1,265 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+
+/**
+ * @file
+ * Interface functions to the internal and external multiplexers.
+ */
+
+
+#ifndef FORWARD_H
+#define FORWARD_H
+
+#include "openvpn.h"
+#include "occ.h"
+#include "ping.h"
+
+#define TUN_OUT(c)      (BLEN(&(c)->c2.to_tun) > 0)
+#define LINK_OUT(c)     (BLEN(&(c)->c2.to_link) > 0)
+#define ANY_OUT(c)      (TUN_OUT(c) || LINK_OUT(c))
+
+#ifdef ENABLE_FRAGMENT
+#define TO_LINK_FRAG(c) ((c)->c2.fragment && fragment_outgoing_defined((c)->c2.fragment))
+#else
+#define TO_LINK_FRAG(c) (false)
+#endif
+
+#define TO_LINK_DEF(c)  (LINK_OUT(c) || TO_LINK_FRAG(c))
+
+#define IOW_TO_TUN          (1<<0)
+#define IOW_TO_LINK         (1<<1)
+#define IOW_READ_TUN        (1<<2)
+#define IOW_READ_LINK       (1<<3)
+#define IOW_SHAPER          (1<<4)
+#define IOW_CHECK_RESIDUAL  (1<<5)
+#define IOW_FRAG            (1<<6)
+#define IOW_MBUF            (1<<7)
+#define IOW_READ_TUN_FORCE  (1<<8)
+#define IOW_WAIT_SIGNAL     (1<<9)
+
+#define IOW_READ            (IOW_READ_TUN|IOW_READ_LINK)
+
+
+void pre_select(struct context *c);
+
+void process_io(struct context *c);
+
+const char *wait_status_string(struct context *c, struct gc_arena *gc);
+
+void show_wait_status(struct context *c);
+
+
+/**********************************************************************/
+/**
+ * Process a data channel packet that will be sent through a VPN tunnel.
+ * @ingroup data_control
+ *
+ * This function controls the processing of a data channel packet which
+ * will be sent through a VPN tunnel to a remote OpenVPN peer.  It's
+ * general structure is as follows:
+ * - Check that the client authentication has succeeded; if not, drop the
+ *   packet.
+ * - If the \a comp_frag argument is true:
+ *   - Call \c lzo_compress() of the \link Data Channel Compression
+ *     module\endlink to (possibly) compress the packet.
+ *   - Call \c fragment_outgoing() of the \link Data Channel Fragmentation
+ *     module\endlink to (possibly) fragment the packet.
+ * - Activate the \link Data Channel Crypto module\endlink to perform
+ *   security operations on the packet.
+ *   - Call \c tls_pre_encrypt() to choose the appropriate security
+ *     parameters for this packet.
+ *   - Call \c openvpn_encrypt() to encrypt and HMAC signed the packet.
+ *   - Call \c tls_post_encrypt() to prepend the one-byte OpenVPN header
+ *     and do some TLS accounting.
+ * - Place the resulting packet in \c c->c2.to_link so that it can be sent
+ *   over the external network interface to its remote destination by the
+ *   \link external_multiplexer External Multiplexer\endlink.
+ *
+ * @param c - The context structure of the VPN tunnel associated with this
+ *     packet.
+ * @param comp_frag - Whether to do packet compression and fragmentation.
+ *     This flag is set to true the first time a packet is processed.  If
+ *     the packet then gets fragmented, this function will be called again
+ *     once for each remaining fragment with this parameter set to false.
+ */
+void encrypt_sign(struct context *c, bool comp_frag);
+
+int get_server_poll_remaining_time(struct event_timeout *server_poll_timeout);
+
+/**********************************************************************/
+/**
+ * Read a packet from the external network interface.
+ * @ingroup external_multiplexer
+ *
+ * The packet read from the external network interface is stored in \c
+ * c->c2.buf and its source address in \c c->c2.from.  If an error
+ * occurred, the length of \c c->c2.buf will be 0.
+ *
+ * OpenVPN running as client or as UDP server only has a single external
+ * network socket, so this function can be called with the single (client
+ * mode) or top level (UDP server) context as its argument. OpenVPN
+ * running as TCP server, on the other hand, has a network socket for each
+ * active VPN tunnel.  In that case this function must be called with the
+ * context associated with the appropriate VPN tunnel for which data is
+ * available to be read.
+ *
+ * @param c - The context structure which contains the external
+ *     network socket from which to read incoming packets.
+ */
+void read_incoming_link(struct context *c);
+
+/**
+ * Starts processing a packet read from the external network interface.
+ * @ingroup external_multiplexer
+ *
+ * This function starts the processing of a data channel packet which
+ * has come out of a VPN tunnel.  It's high-level structure is as follows:
+ * - Verify that a nonzero length packet has been received from a valid
+ *   source address for the given context \a c.
+ * - Call \c tls_pre_decrypt(), which splits data channel and control
+ *   channel packets:
+ *   - If a data channel packet, the appropriate security parameters are
+ *     loaded.
+ *   - If a control channel packet, this function process is it and
+ *     afterwards sets the packet's buffer length to 0, so that the data
+ *     channel processing steps below will ignore it.
+ * - Call \c openvpn_decrypt() of the \link data_crypto Data Channel
+ *   Crypto module\endlink to authenticate and decrypt the packet using
+ *   the security parameters loaded by \c tls_pre_decrypt() above.
+ *
+ * @param c - The context structure of the VPN tunnel associated with the
+ *     packet.
+ * @param lsi - link_socket_info obtained from context before processing.
+ * @param floated - Flag indicates that peer has floated.
+ *
+ * @return true if packet is authenticated, false otherwise.
+ */
+bool process_incoming_link_part1(struct context *c, struct link_socket_info *lsi, bool floated);
+
+/**
+ * Continues processing a packet read from the external network interface.
+ * @ingroup external_multiplexer
+ *
+ * This function continues the processing of a data channel packet which
+ * has come out of a VPN tunnel. It must be called after
+ * \c process_incoming_link_part1() function.
+ *
+ * It's high-level structure is as follows:
+ * - Call \c fragment_incoming() of the \link fragmentation Data Channel
+ *   Fragmentation module\endlink to reassemble the packet if it's
+ *   fragmented.
+ * - Call \c lzo_decompress() of the \link compression Data Channel
+ *   Compression module\endlink to decompress the packet if it's
+ *   compressed.
+ * - Place the resulting packet in \c c->c2.to_tun so that it can be sent
+ *   over the virtual tun/tap network interface to its local destination
+ *   by the \link internal_multiplexer Internal Multiplexer\endlink.
+ *
+ * @param c - The context structure of the VPN tunnel associated with the
+ *     packet.
+ * @param lsi - link_socket_info obtained from context before processing.
+ * @param orig_buf - Pointer to a buffer data.
+ *
+ */
+void process_incoming_link_part2(struct context *c, struct link_socket_info *lsi, const uint8_t *orig_buf);
+
+/**
+ * Write a packet to the external network interface.
+ * @ingroup external_multiplexer
+ *
+ * This function writes the packet stored in \c c->c2.to_link to the
+ * external network device contained within \c c->c1.link_socket.
+ *
+ * If an error occurs, it is logged and the packet is dropped.
+ *
+ * @param c - The context structure of the VPN tunnel associated with the
+ *     packet.
+ */
+void process_outgoing_link(struct context *c);
+
+
+/**************************************************************************/
+/**
+ * Read a packet from the virtual tun/tap network interface.
+ * @ingroup internal_multiplexer
+ *
+ * This function reads a packet from the virtual tun/tap network device \c
+ * c->c1.tuntap and stores it in \c c->c2.buf.
+ *
+ * If an error occurs, it is logged and the packet is dropped.
+ *
+ * @param c - The context structure in which to store the received
+ *     packet.
+ */
+void read_incoming_tun(struct context *c);
+
+
+/**
+ * Process a packet read from the virtual tun/tap network interface.
+ * @ingroup internal_multiplexer
+ *
+ * This function calls \c encrypt_sign() of the \link data_control Data
+ * Channel Control module\endlink to process the packet.
+ *
+ * If an error occurs, it is logged and the packet is dropped.
+ *
+ * @param c - The context structure of the VPN tunnel associated with the
+ *     packet.
+ */
+void process_incoming_tun(struct context *c);
+
+
+/**
+ * Write a packet to the virtual tun/tap network interface.
+ * @ingroup internal_multiplexer
+ *
+ * This function writes the packet stored in \c c->c2.to_tun to the
+ * virtual tun/tap network device \c c->c1.tuntap.
+ *
+ * If an error occurs, it is logged and the packet is dropped.
+ *
+ * @param c - The context structure of the VPN tunnel associated with
+ *     the packet.
+ */
+void process_outgoing_tun(struct context *c);
+
+
+/**************************************************************************/
+
+bool send_control_channel_string(struct context *c, const char *str, int msglevel);
+
+#define PIPV4_PASSTOS         (1<<0)
+#define PIP_MSSFIX            (1<<1)         /* v4 and v6 */
+#define PIPV4_OUTGOING        (1<<2)
+#define PIPV4_EXTRACT_DHCP_ROUTER (1<<3)
+#define PIPV4_CLIENT_NAT      (1<<4)
+
+void process_ip_header(struct context *c, unsigned int flags, struct buffer *buf);
+
+#if P2MP
+void schedule_exit(struct context *c, const int n_seconds, const int signal);
+
+#endif
+
+#endif /* FORWARD_H */
diff --git a/src/openvpn/fragment.c b/src/openvpn/fragment.c
new file mode 100644
index 0000000..4eb1dd2
--- /dev/null
+++ b/src/openvpn/fragment.c
@@ -0,0 +1,444 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_FRAGMENT
+
+#include "misc.h"
+#include "fragment.h"
+#include "integer.h"
+#include "memdbg.h"
+
+#define FRAG_ERR(s) { errmsg = s; goto error; }
+
+static void
+fragment_list_buf_init(struct fragment_list *list, const struct frame *frame)
+{
+    int i;
+    for (i = 0; i < N_FRAG_BUF; ++i)
+    {
+        list->fragments[i].buf = alloc_buf(BUF_SIZE(frame));
+    }
+}
+
+static void
+fragment_list_buf_free(struct fragment_list *list)
+{
+    int i;
+    for (i = 0; i < N_FRAG_BUF; ++i)
+    {
+        free_buf(&list->fragments[i].buf);
+    }
+}
+
+/*
+ * Given a sequence ID number, get a fragment buffer.  Use a sliding window,
+ * similar to packet_id code.
+ */
+static struct fragment *
+fragment_list_get_buf(struct fragment_list *list, int seq_id)
+{
+    int diff;
+    if (abs(diff = modulo_subtract(seq_id, list->seq_id, N_SEQ_ID)) >= N_FRAG_BUF)
+    {
+        int i;
+        for (i = 0; i < N_FRAG_BUF; ++i)
+        {
+            list->fragments[i].defined = false;
+        }
+        list->index = 0;
+        list->seq_id = seq_id;
+        diff = 0;
+    }
+    while (diff > 0)
+    {
+        list->fragments[list->index = modulo_add(list->index, 1, N_FRAG_BUF)].defined = false;
+        list->seq_id = modulo_add(list->seq_id, 1, N_SEQ_ID);
+        --diff;
+    }
+    return &list->fragments[modulo_add(list->index, diff, N_FRAG_BUF)];
+}
+
+struct fragment_master *
+fragment_init(struct frame *frame)
+{
+    struct fragment_master *ret;
+
+    /* code that initializes other parts of
+     * fragment_master assume an initial CLEAR */
+    ALLOC_OBJ_CLEAR(ret, struct fragment_master);
+
+    /* add in the size of our contribution to the expanded frame size */
+    frame_add_to_extra_frame(frame, sizeof(fragment_header_type));
+
+    /*
+     * Outgoing sequence ID is randomized to reduce
+     * the probability of sequence number collisions
+     * when openvpn sessions are restarted.  This is
+     * not done out of any need for security, as all
+     * fragmentation control information resides
+     * inside of the encrypted/authenticated envelope.
+     */
+    ret->outgoing_seq_id = (int)get_random() & (N_SEQ_ID - 1);
+
+    event_timeout_init(&ret->wakeup, FRAG_WAKEUP_INTERVAL, now);
+
+    return ret;
+}
+
+void
+fragment_free(struct fragment_master *f)
+{
+    fragment_list_buf_free(&f->incoming);
+    free_buf(&f->outgoing);
+    free_buf(&f->outgoing_return);
+    free(f);
+}
+
+void
+fragment_frame_init(struct fragment_master *f, const struct frame *frame)
+{
+    fragment_list_buf_init(&f->incoming, frame);
+    f->outgoing = alloc_buf(BUF_SIZE(frame));
+    f->outgoing_return = alloc_buf(BUF_SIZE(frame));
+}
+
+/*
+ * Accept an incoming datagram (which may be a fragment) from remote.
+ * If the datagram is whole (i.e not a fragment), pass through.
+ * If the datagram is a fragment, join with other fragments received so far.
+ * If a fragment fully completes the datagram, return the datagram.
+ */
+void
+fragment_incoming(struct fragment_master *f, struct buffer *buf,
+                  const struct frame *frame)
+{
+    const char *errmsg = NULL;
+    fragment_header_type flags = 0;
+    int frag_type = 0;
+
+    if (buf->len > 0)
+    {
+        /* get flags from packet head */
+        if (!buf_read(buf, &flags, sizeof(flags)))
+        {
+            FRAG_ERR("flags not found in packet");
+        }
+        flags = ntoh_fragment_header_type(flags);
+
+        /* get fragment type from flags */
+        frag_type = ((flags >> FRAG_TYPE_SHIFT) & FRAG_TYPE_MASK);
+
+#if 0
+        /*
+         * If you want to extract FRAG_EXTRA_MASK/FRAG_EXTRA_SHIFT bits,
+         * do it here.
+         */
+        if (frag_type == FRAG_WHOLE || frag_type == FRAG_YES_NOTLAST)
+        {
+        }
+#endif
+
+        /* handle the fragment type */
+        if (frag_type == FRAG_WHOLE)
+        {
+            dmsg(D_FRAG_DEBUG,
+                 "FRAG_IN buf->len=%d type=FRAG_WHOLE flags="
+                 fragment_header_format,
+                 buf->len,
+                 flags);
+
+            if (flags & (FRAG_SEQ_ID_MASK | FRAG_ID_MASK))
+            {
+                FRAG_ERR("spurrious FRAG_WHOLE flags");
+            }
+        }
+        else if (frag_type == FRAG_YES_NOTLAST || frag_type == FRAG_YES_LAST)
+        {
+            const int seq_id = ((flags >> FRAG_SEQ_ID_SHIFT) & FRAG_SEQ_ID_MASK);
+            const int n = ((flags >> FRAG_ID_SHIFT) & FRAG_ID_MASK);
+            const int size = ((frag_type == FRAG_YES_LAST)
+                              ? (int)(((flags >> FRAG_SIZE_SHIFT) & FRAG_SIZE_MASK) << FRAG_SIZE_ROUND_SHIFT)
+                              : buf->len);
+
+            /* get the appropriate fragment buffer based on received seq_id */
+            struct fragment *frag = fragment_list_get_buf(&f->incoming, seq_id);
+
+            dmsg(D_FRAG_DEBUG,
+                 "FRAG_IN len=%d type=%d seq_id=%d frag_id=%d size=%d flags="
+                 fragment_header_format,
+                 buf->len,
+                 frag_type,
+                 seq_id,
+                 n,
+                 size,
+                 flags);
+
+            /* make sure that size is an even multiple of 1<<FRAG_SIZE_ROUND_SHIFT */
+            if (size & FRAG_SIZE_ROUND_MASK)
+            {
+                FRAG_ERR("bad fragment size");
+            }
+
+            /* is this the first fragment for our sequence number? */
+            if (!frag->defined || frag->max_frag_size != size)
+            {
+                frag->defined = true;
+                frag->max_frag_size = size;
+                frag->map = 0;
+                ASSERT(buf_init(&frag->buf, FRAME_HEADROOM_ADJ(frame, FRAME_HEADROOM_MARKER_FRAGMENT)));
+            }
+
+            /* copy the data to fragment buffer */
+            if (!buf_copy_range(&frag->buf, n * size, buf, 0, buf->len))
+            {
+                FRAG_ERR("fragment buffer overflow");
+            }
+
+            /* set elements in bit array to reflect which fragments have been received */
+            frag->map |= (((frag_type == FRAG_YES_LAST) ? FRAG_MAP_MASK : 1) << n);
+
+            /* update timestamp on partially built datagram */
+            frag->timestamp = now;
+
+            /* received full datagram? */
+            if ((frag->map & FRAG_MAP_MASK) == FRAG_MAP_MASK)
+            {
+                frag->defined = false;
+                *buf = frag->buf;
+            }
+            else
+            {
+                buf->len = 0;
+            }
+        }
+        else if (frag_type == FRAG_TEST)
+        {
+            FRAG_ERR("FRAG_TEST not implemented");
+        }
+        else
+        {
+            FRAG_ERR("unknown fragment type");
+        }
+    }
+
+    return;
+
+error:
+    if (errmsg)
+    {
+        msg(D_FRAG_ERRORS, "FRAG_IN error flags=" fragment_header_format ": %s", flags, errmsg);
+    }
+    buf->len = 0;
+    return;
+}
+
+/* pack fragment parms into a uint32_t and prepend to buffer */
+static void
+fragment_prepend_flags(struct buffer *buf,
+                       int type,
+                       int seq_id,
+                       int frag_id,
+                       int frag_size)
+{
+    fragment_header_type flags = ((type & FRAG_TYPE_MASK) << FRAG_TYPE_SHIFT)
+                                 | ((seq_id & FRAG_SEQ_ID_MASK) << FRAG_SEQ_ID_SHIFT)
+                                 | ((frag_id & FRAG_ID_MASK) << FRAG_ID_SHIFT);
+
+    if (type == FRAG_WHOLE || type == FRAG_YES_NOTLAST)
+    {
+        /*
+         * If you want to set FRAG_EXTRA_MASK/FRAG_EXTRA_SHIFT bits,
+         * do it here.
+         */
+        dmsg(D_FRAG_DEBUG,
+             "FRAG_OUT len=%d type=%d seq_id=%d frag_id=%d frag_size=%d flags="
+             fragment_header_format,
+             buf->len, type, seq_id, frag_id, frag_size, flags);
+    }
+    else
+    {
+        flags |= (((frag_size >> FRAG_SIZE_ROUND_SHIFT) & FRAG_SIZE_MASK) << FRAG_SIZE_SHIFT);
+
+        dmsg(D_FRAG_DEBUG,
+             "FRAG_OUT len=%d type=%d seq_id=%d frag_id=%d frag_size=%d flags="
+             fragment_header_format,
+             buf->len, type, seq_id, frag_id, frag_size, flags);
+    }
+
+    flags = hton_fragment_header_type(flags);
+    ASSERT(buf_write_prepend(buf, &flags, sizeof(flags)));
+}
+
+/*
+ * Without changing the number of fragments, return a possibly smaller
+ * max fragment size that will allow for the last fragment to be of
+ * similar size as previous fragments.
+ */
+static inline int
+optimal_fragment_size(int len, int max_frag_size)
+{
+    const int mfs_aligned = (max_frag_size & ~FRAG_SIZE_ROUND_MASK);
+    const int div = len / mfs_aligned;
+    const int mod = len % mfs_aligned;
+
+    if (div > 0 && mod > 0 && mod < mfs_aligned * 3 / 4)
+    {
+        return min_int(mfs_aligned, (max_frag_size - ((max_frag_size - mod) / (div + 1))
+                                     + FRAG_SIZE_ROUND_MASK) & ~FRAG_SIZE_ROUND_MASK);
+    }
+    else
+    {
+        return mfs_aligned;
+    }
+}
+
+/* process an outgoing datagram, possibly breaking it up into fragments */
+void
+fragment_outgoing(struct fragment_master *f, struct buffer *buf,
+                  const struct frame *frame)
+{
+    const char *errmsg = NULL;
+    if (buf->len > 0)
+    {
+        /* The outgoing buffer should be empty so we can put new data in it */
+        if (f->outgoing.len)
+        {
+            msg(D_FRAG_ERRORS, "FRAG: outgoing buffer is not empty, len=[%d,%d]",
+                buf->len, f->outgoing.len);
+        }
+        if (buf->len > PAYLOAD_SIZE_DYNAMIC(frame)) /* should we fragment? */
+        {
+            /*
+             * Send the datagram as a series of 2 or more fragments.
+             */
+            f->outgoing_frag_size = optimal_fragment_size(buf->len, PAYLOAD_SIZE_DYNAMIC(frame));
+            if (buf->len > f->outgoing_frag_size * MAX_FRAGS)
+            {
+                FRAG_ERR("too many fragments would be required to send datagram");
+            }
+            ASSERT(buf_init(&f->outgoing, FRAME_HEADROOM(frame)));
+            ASSERT(buf_copy(&f->outgoing, buf));
+            f->outgoing_seq_id = modulo_add(f->outgoing_seq_id, 1, N_SEQ_ID);
+            f->outgoing_frag_id = 0;
+            buf->len = 0;
+            ASSERT(fragment_ready_to_send(f, buf, frame));
+        }
+        else
+        {
+            /*
+             * Send the datagram whole.
+             */
+            fragment_prepend_flags(buf,
+                                   FRAG_WHOLE,
+                                   0,
+                                   0,
+                                   0);
+        }
+    }
+    return;
+
+error:
+    if (errmsg)
+    {
+        msg(D_FRAG_ERRORS, "FRAG_OUT error, len=%d frag_size=%d MAX_FRAGS=%d: %s",
+            buf->len, f->outgoing_frag_size, MAX_FRAGS, errmsg);
+    }
+    buf->len = 0;
+    return;
+}
+
+/* return true (and set buf) if we have an outgoing fragment which is ready to send */
+bool
+fragment_ready_to_send(struct fragment_master *f, struct buffer *buf,
+                       const struct frame *frame)
+{
+    if (fragment_outgoing_defined(f))
+    {
+        /* get fragment size, and determine if it is the last fragment */
+        int size = f->outgoing_frag_size;
+        int last = false;
+        if (f->outgoing.len <= size)
+        {
+            size = f->outgoing.len;
+            last = true;
+        }
+
+        /* initialize return buffer */
+        *buf = f->outgoing_return;
+        ASSERT(buf_init(buf, FRAME_HEADROOM(frame)));
+        ASSERT(buf_copy_n(buf, &f->outgoing, size));
+
+        /* fragment flags differ based on whether or not we are sending the last fragment */
+        fragment_prepend_flags(buf,
+                               last ? FRAG_YES_LAST : FRAG_YES_NOTLAST,
+                               f->outgoing_seq_id,
+                               f->outgoing_frag_id++,
+                               f->outgoing_frag_size);
+
+        ASSERT(!last || !f->outgoing.len); /* outgoing buffer length should be zero after last fragment sent */
+
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static void
+fragment_ttl_reap(struct fragment_master *f)
+{
+    int i;
+    for (i = 0; i < N_FRAG_BUF; ++i)
+    {
+        struct fragment *frag = &f->incoming.fragments[i];
+        if (frag->defined && frag->timestamp + FRAG_TTL_SEC <= now)
+        {
+            msg(D_FRAG_ERRORS, "FRAG TTL expired i=%d", i);
+            frag->defined = false;
+        }
+    }
+}
+
+/* called every FRAG_WAKEUP_INTERVAL seconds */
+void
+fragment_wakeup(struct fragment_master *f, struct frame *frame)
+{
+    /* delete fragments with expired TTLs */
+    fragment_ttl_reap(f);
+}
+
+#else  /* ifdef ENABLE_FRAGMENT */
+static void
+dummy(void)
+{
+}
+#endif /* ifdef ENABLE_FRAGMENT */
diff --git a/src/openvpn/fragment.h b/src/openvpn/fragment.h
new file mode 100644
index 0000000..6fa9692
--- /dev/null
+++ b/src/openvpn/fragment.h
@@ -0,0 +1,480 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef FRAGMENT_H
+#define FRAGMENT_H
+
+/**
+ * @file
+ * Data Channel Fragmentation module header file.
+ */
+
+
+#ifdef ENABLE_FRAGMENT
+
+/**
+ * @addtogroup fragmentation
+ * @{
+ */
+
+
+#include "common.h"
+#include "buffer.h"
+#include "interval.h"
+#include "mtu.h"
+#include "shaper.h"
+#include "error.h"
+
+
+#define N_FRAG_BUF                   25
+/**< Number of packet buffers for
+ *   reassembling incoming fragmented
+ *   packets. */
+
+#define FRAG_TTL_SEC                 10
+/**< Time-to-live in seconds for a %fragment. */
+
+#define FRAG_WAKEUP_INTERVAL         5
+/**< Interval in seconds between calls to
+ *   wakeup code. */
+
+/**************************************************************************/
+/**
+ * Structure for reassembling one incoming fragmented packet.
+ */
+struct fragment {
+    bool defined;               /**< Whether reassembly is currently
+                                 *   taking place in this structure. */
+
+    int max_frag_size;          /**< Maximum size of each %fragment. */
+
+#define FRAG_MAP_MASK 0xFFFFFFFF
+    /**< Mask for reassembly map. */
+#define MAX_FRAGS 32            /**< Maximum number of fragments per packet. */
+    unsigned int map;
+    /**< Reassembly map for recording which
+     *   fragments have been received.
+     *
+     *   A bit array where each bit
+     *   corresponds to a %fragment.  A 1 bit
+     *   in element n means that the %fragment
+     *   n has been received.  Needs to have
+     *   at least \c MAX_FRAGS bits. */
+
+    time_t timestamp;           /**< Timestamp for time-to-live purposes. */
+
+    struct buffer buf;          /**< Buffer in which received datagrams
+                                 *   are reassembled. */
+};
+
+
+/**
+ * List of fragment structures for reassembling multiple incoming packets
+ * concurrently.
+ */
+struct fragment_list {
+    int seq_id;                 /**< Highest fragmentation sequence ID of
+                                 *   the packets currently being
+                                 *   reassembled. */
+    int index;                  /**< Index of the packet being reassembled
+                                 *   with the highest fragmentation
+                                 *   sequence ID into the \c
+                                 *   fragment_list.fragments array. */
+
+/** Array of reassembly structures, each can contain one whole packet.
+ *
+ *  The fragmentation sequence IDs of the packets being reassembled in
+ *  this array are linearly increasing. \c
+ *  fragment_list.fragments[fragment_list.index] has an ID of \c
+ *  fragment_list.seq_id.  This means that one of these \c fragment_list
+ *  structures can at any one time contain at most packets with the
+ *  fragmentation sequence IDs in the range \c fragment_list.seq_id \c -
+ *  \c N_FRAG_BUF \c + \c 1 to \c fragment_list.seq_id, inclusive.
+ */
+    struct fragment fragments[N_FRAG_BUF];
+};
+
+
+/**
+ * Fragmentation and reassembly state for one VPN tunnel instance.
+ *
+ * This structure contains all the state necessary for sending and
+ * receiving fragmented data channel packets associated with one VPN
+ * tunnel.
+ *
+ * The fragmented packet currently being sent to a remote OpenVPN peer is
+ * stored in \c fragment_master.outgoing.  It is copied into that buffer
+ * by the \c fragment_outgoing() function and the remaining parts to be
+ * sent can be retrieved by successive calls to \c
+ * fragment_ready_to_send().
+ *
+ * The received packets currently being reassembled are stored in the \c
+ * fragment_master.incoming array of \c fragment structures.  The \c
+ * fragment_incoming() function adds newly received parts into this array
+ * and returns the whole packets once reassembly is complete.
+ */
+struct fragment_master {
+    struct event_timeout wakeup; /**< Timeout structure used by the main
+                                  *   event loop to know when to do
+                                  *   fragmentation housekeeping. */
+    bool received_os_mtu_hint;  /**< Whether the operating system has
+                                 *   explicitly recommended an MTU value. */
+#define N_SEQ_ID            256
+    /**< One more than the maximum fragment
+     *   sequence ID, above which the IDs wrap
+     *   to zero.  Should be a power of 2. */
+    int outgoing_seq_id;        /**< Fragment sequence ID of the current
+                                 *   fragmented packet waiting to be sent.
+                                 *
+                                 *   All parts of a fragmented packet
+                                 *   share the same sequence ID, so that
+                                 *   the remote OpenVPN peer can determine
+                                 *   which parts belong to which original
+                                 *   packet. */
+#define MAX_FRAG_PKT_SIZE 65536
+    /**< (Not used) Maximum packet size before
+     *   fragmenting. */
+    int outgoing_frag_size;     /**< Size in bytes of each part to be
+                                 *   sent, except for the last part which
+                                 *   may be smaller.
+                                 *
+                                 *   This value is computed by the \c
+                                 *   optimal_fragment_size() function. Its
+                                 *   value is sent to the remote peer in
+                                 *   the fragmentation header of the last
+                                 *   part (i.e. with %fragment type \c
+                                 *   FRAG_YES_LAST) using the \c
+                                 *   FRAG_SIZE_MASK and \c FRAG_SIZE_SHIFT
+                                 *   bits. */
+    int outgoing_frag_id;       /**< The fragment ID of the next part to
+                                 *   be sent.  Must have a value between 0
+                                 *   and \c MAX_FRAGS-1. */
+    struct buffer outgoing;     /**< Buffer containing the remaining parts
+                                 *   of the fragmented packet being sent. */
+    struct buffer outgoing_return;
+    /**< Buffer used by \c
+     *   fragment_ready_to_send() to return a
+     *   part to send. */
+
+    struct fragment_list incoming;
+    /**< List of structures for reassembling
+     *   incoming packets. */
+};
+
+
+/**************************************************************************/
+/** @name Fragment header
+ *  @todo Add description of %fragment header format.
+ *//** @{ *//*************************************/
+
+typedef uint32_t fragment_header_type;
+/**< Fragmentation information is stored in
+ *   a 32-bit packet header. */
+
+#define hton_fragment_header_type(x) htonl(x)
+/**< Convert a fragment_header_type from
+ *   host to network order. */
+
+#define ntoh_fragment_header_type(x) ntohl(x)
+/**< Convert a \c fragment_header_type
+ *   from network to host order. */
+
+#define FRAG_TYPE_MASK        0x00000003
+/**< Bit mask for %fragment type info. */
+#define FRAG_TYPE_SHIFT       0 /**< Bit shift for %fragment type info. */
+
+#define FRAG_WHOLE            0 /**< Fragment type indicating packet is
+                                 *   whole. */
+#define FRAG_YES_NOTLAST      1 /**< Fragment type indicating packet is
+                                 *   part of a fragmented packet, but not
+                                 *   the last part in the sequence. */
+#define FRAG_YES_LAST         2 /**< Fragment type indicating packet is
+                                 *   the last part in the sequence of
+                                 *   parts. */
+#define FRAG_TEST             3 /**< Fragment type not implemented yet.
+                                 *   In the future might be used as a
+                                 *   control packet for establishing MTU
+                                 *   size. */
+
+#define FRAG_SEQ_ID_MASK      0x000000ff
+/**< Bit mask for %fragment sequence ID. */
+#define FRAG_SEQ_ID_SHIFT     2 /**< Bit shift for %fragment sequence ID. */
+
+#define FRAG_ID_MASK          0x0000001f
+/**< Bit mask for %fragment ID. */
+#define FRAG_ID_SHIFT         10
+/**< Bit shift for %fragment ID. */
+
+/*
+ * FRAG_SIZE  14 bits
+ *
+ * IF FRAG_YES_LAST (FRAG_SIZE):
+ *   The max size of a %fragment.  If a %fragment is not the last %fragment in the packet,
+ *   then the %fragment size is guaranteed to be equal to the max %fragment size.  Therefore,
+ *   max_frag_size is only sent over the wire if FRAG_LAST is set.  Otherwise it is assumed
+ *   to be the actual %fragment size received.
+ */
+#define FRAG_SIZE_MASK        0x00003fff
+/**< Bit mask for %fragment size. */
+#define FRAG_SIZE_SHIFT       15
+/**< Bit shift for %fragment size. */
+#define FRAG_SIZE_ROUND_SHIFT 2 /**< Bit shift for %fragment size rounding. */
+#define FRAG_SIZE_ROUND_MASK ((1 << FRAG_SIZE_ROUND_SHIFT) - 1)
+/**< Bit mask for %fragment size rounding. */
+
+/*
+ * FRAG_EXTRA 16 bits
+ *
+ * IF FRAG_WHOLE or FRAG_YES_NOTLAST, these 16 bits are available (not currently used)
+ */
+#define FRAG_EXTRA_MASK         0x0000ffff
+/**< Bit mask for extra bits. */
+#define FRAG_EXTRA_SHIFT        15
+/**< Bit shift for extra bits. */
+
+/** @} name Fragment header *//********************************************/
+
+
+/**************************************************************************/
+/** @name Functions for initialization and cleanup *//** @{ *//************/
+
+/**
+ * Allocate and initialize a \c fragment_master structure.
+ *
+ * This function also modifies the \a frame packet geometry parameters to
+ * include space for the fragmentation header.
+ *
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel, modified by this function to include the
+ *                       fragmentation header.
+ *
+ * @return A pointer to the new \c fragment_master structure.
+ */
+struct fragment_master *fragment_init(struct frame *frame);
+
+
+/**
+ * Allocate internal packet buffers for a \c fragment_master structure.
+ *
+ * @param f            - The \c fragment_master structure for which to
+ *                       allocate the internal buffers.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel, used to determine how much memory to
+ *                       allocate for each packet buffer.
+ */
+void fragment_frame_init(struct fragment_master *f, const struct frame *frame);
+
+
+/**
+ * Free a \c fragment_master structure and its internal packet buffers.
+ *
+ * @param f            - The \c fragment_master structure to free.
+ */
+void fragment_free(struct fragment_master *f);
+
+/** @} name Functions for initialization and cleanup *//*******************/
+
+
+/**************************************************************************/
+/** @name Functions for processing packets received from a remote OpenVPN peer */
+/** @{ */
+
+/**
+ * Process an incoming packet, which may or may not be fragmented.
+ *
+ * This function inspects the fragmentation header of the incoming packet
+ * and processes the packet accordingly. Depending on the %fragment type
+ * bits (\c FRAG_TYPE_MASK and \c FRAG_TYPE_SHIFT) the packet is processed
+ * in the following ways:
+ *  - \c FRAG_WHOLE: the packet is not fragmented, and this function does
+ *    not modify its contents, except for removing the fragmentation
+ *    header.
+ *  - \c FRAG_YES_NOTLAST or \c FRAG_YES_LAST: the packet is part of a
+ *    fragmented packet.  This function copies the packet into an internal
+ *    reassembly buffer.  If the incoming part completes the packet being
+ *    reassembled, the \a buf argument is modified to point to the fully
+ *    reassembled packet.  If, on the other hand, reassembly is not yet
+ *    complete, then the the \a buf buffer is set to empty.
+ *  - Any other value: error.
+ *
+ * If an error occurs during processing, an error message is logged and
+ * the length of \a buf is set to zero.
+ *
+ * @param f            - The \c fragment_master structure for this VPN
+ *                       tunnel.
+ * @param buf          - A pointer to the buffer structure containing the
+ *                       incoming packet.  This pointer will have been
+ *                       modified on return either to point to a
+ *                       completely reassembled packet, or to have length
+ *                       set to zero if reassembly is not yet complete.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel.
+ *
+ * @return Void.\n On return, the \a buf argument will point to a buffer.
+ *     The buffer will have nonzero length if the incoming packet passed
+ *     to this function was whole and unfragmented, or if it was the final
+ *     part of a fragmented packet thereby completing reassembly.  On the
+ *     other hand, the buffer will have a length of zero if the incoming
+ *     packet was part of a fragmented packet and reassembly is not yet
+ *     complete.  If an error occurs during processing, the buffer length
+ *     is also set to zero.
+ */
+void fragment_incoming(struct fragment_master *f, struct buffer *buf,
+                       const struct frame *frame);
+
+/** @} name Functions for processing packets received from a VPN tunnel */
+
+
+/**************************************************************************/
+/** @name Functions for processing packets to be sent to a remote OpenVPN peer */
+/** @{ */
+
+/**
+ * Process an outgoing packet, which may or may not need to be fragmented.
+ *
+ * This function inspects the outgoing packet, determines whether it needs
+ * to be fragmented, and processes it accordingly.
+ *
+ * Depending on the size of the outgoing packet and the packet geometry
+ * parameters for the VPN tunnel, the packet will or will not be
+ * fragmented.
+ * @li Packet size is less than or equal to the maximum packet size for
+ *     this VPN tunnel: fragmentation is not necessary.  The \a buf
+ *     argument points to a buffer containing the unmodified outgoing
+ *     packet with a fragmentation header indicating the packet is whole
+ *     (FRAG_WHOLE) prepended.
+ * @li Packet size is greater than the maximum packet size for this VPN
+ *     tunnel: fragmentation is necessary.  The original outgoing packet
+ *     is copied into an internal buffer for fragmentation.  The \a buf
+ *     argument is modified to point to the first part of the fragmented
+ *     packet. The remaining parts remain stored in the internal buffer,
+ *     and can be retrieved using the \c fragment_ready_to_send()
+ *     function.
+ *
+ * If an error occurs during processing, an error message is logged and
+ * the length of \a buf is set to zero.
+ *
+ * @param f            - The \c fragment_master structure for this VPN
+ *                       tunnel.
+ * @param buf          - A pointer to the buffer structure containing the
+ *                       outgoing packet.  This pointer will be modified
+ *                       to point to a whole unfragmented packet or to the
+ *                       first part of a fragmented packet on return.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel.
+ *
+ * @return Void.\n On return, the \a buf argument will point to a buffer.
+ *     This buffer contains either the whole original outgoing packet if
+ *     fragmentation was not necessary, or the first part of the
+ *     fragmented outgoing packet if fragmentation was necessary. In both
+ *     cases a fragmentation header will have been prepended to inform the
+ *     remote peer how to handle the packet.
+ */
+void fragment_outgoing(struct fragment_master *f, struct buffer *buf,
+                       const struct frame *frame);
+
+/**
+ * Check whether outgoing fragments are ready to be send, and if so make
+ * one available.
+ *
+ * This function checks whether the internal buffer for fragmenting
+ * outgoing packets contains any unsent parts.  If it does not, meaning
+ * there is nothing waiting to be sent, it returns false.  Otherwise there
+ * are parts ready to be sent, and it returns true.  In that case it also
+ * modifies the \a buf argument to point to a buffer containing the next
+ * part to be sent.
+ *
+ * @param f            - The \a fragment_master structure for this VPN
+ *                       tunnel.
+ * @param buf          - A pointer to a buffer structure which on return,
+ *                       if there are parts waiting to be sent, will point
+ *                       to the next part to be sent.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel.
+ *
+ * @return
+ * @li True, if an outgoing packet has been fragmented and not all parts
+ *     have been sent yet.  In this case this function will modify the \a
+ *     buf argument to point to a buffer containing the next part to be
+ *     sent.
+ * @li False, if there are no outgoing fragmented parts waiting to be
+ *     sent.
+ */
+bool fragment_ready_to_send(struct fragment_master *f, struct buffer *buf,
+                            const struct frame *frame);
+
+/**
+ * Check whether a \c fragment_master structure contains fragments ready
+ * to be sent.
+ *
+ * @param f            - The \c fragment_master structure for this VPN
+ *                       tunnel.
+ *
+ * @return
+ * @li True, if there are one or more fragments ready to be sent.
+ * @li False, otherwise.
+ */
+static inline bool
+fragment_outgoing_defined(struct fragment_master *f)
+{
+    return f->outgoing.len > 0;
+}
+
+/** @} name Functions for processing packets going out through a VPN tunnel */
+
+
+void fragment_wakeup(struct fragment_master *f, struct frame *frame);
+
+
+/**************************************************************************/
+/** @name Functions for regular housekeeping *//** @{ *//******************/
+
+/**
+ * Perform housekeeping of a \c fragment_master structure.
+ *
+ * Housekeeping includes scanning incoming packet reassembly buffers for
+ * packets which have not yet been reassembled completely but are already
+ * older than their time-to-live.
+ *
+ * @param f            - The \c fragment_master structure for this VPN
+ *                       tunnel.
+ * @param frame        - The packet geometry parameters for this VPN
+ *                       tunnel.
+ */
+static inline void
+fragment_housekeeping(struct fragment_master *f, struct frame *frame, struct timeval *tv)
+{
+    if (event_timeout_trigger(&f->wakeup, tv, ETT_DEFAULT))
+    {
+        fragment_wakeup(f, frame);
+    }
+}
+
+/** @} name Functions for regular housekeeping *//*************************/
+
+
+/** @} addtogroup fragmentation *//****************************************/
+
+
+#endif /* ifdef ENABLE_FRAGMENT */
+#endif /* ifndef FRAGMENT_H */
diff --git a/src/openvpn/gremlin.c b/src/openvpn/gremlin.c
new file mode 100644
index 0000000..114cb19
--- /dev/null
+++ b/src/openvpn/gremlin.c
@@ -0,0 +1,241 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Test protocol robustness by simulating dropped packets and
+ * network outages when the --gremlin option is used.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_DEBUG
+
+#include "error.h"
+#include "common.h"
+#include "misc.h"
+#include "otime.h"
+#include "gremlin.h"
+
+#include "memdbg.h"
+
+/*
+ * Parameters for packet corruption and droppage.
+ * Each parameter has 4 possible levels, 0 = disabled,
+ * while 1, 2, and 3 are enumerated in the below arrays.
+ * The parameter is a 2-bit field within the --gremlin
+ * parameter.
+ */
+
+/*
+ * Probability that we will drop a packet is 1 / n
+ */
+static const int drop_freq[] = { 500, 100, 50 };
+
+/*
+ * Probability that we will corrupt a packet is 1 / n
+ */
+static const int corrupt_freq[] = { 500, 100, 50 };
+
+/*
+ * When network goes up, it will be up for between
+ * UP_LOW and UP_HIGH seconds.
+ */
+static const int up_low[] =  {  60, 10,  5 };
+static const int up_high[] = { 600, 60, 10 };
+
+/*
+ * When network goes down, it will be down for between
+ * DOWN_LOW and DOWN_HIGH seconds.
+ */
+static const int down_low[] =  {  5, 10,  10 };
+static const int down_high[] = { 10, 60, 120 };
+
+/*
+ * Packet flood levels:
+ *  { number of packets, packet size }
+ */
+static const struct packet_flood_parms packet_flood_data[] =
+{{10, 100}, {10, 1500}, {100, 1500}};
+
+struct packet_flood_parms
+get_packet_flood_parms(int level)
+{
+    ASSERT(level > 0 && level < 4);
+    return packet_flood_data [level - 1];
+}
+
+/*
+ * Return true with probability 1/n
+ */
+static bool
+flip(int n)
+{
+    return (get_random() % n) == 0;
+}
+
+/*
+ * Return uniformly distributed random number between
+ * low and high.
+ */
+static int
+roll(int low, int high)
+{
+    int ret;
+    ASSERT(low <= high);
+    ret = low + (get_random() % (high - low + 1));
+    ASSERT(ret >= low && ret <= high);
+    return ret;
+}
+
+static bool initialized; /* GLOBAL */
+static bool up;          /* GLOBAL */
+static time_t next;      /* GLOBAL */
+
+/*
+ * Return false if we should drop a packet.
+ */
+bool
+ask_gremlin(int flags)
+{
+    const int up_down_level = GREMLIN_UP_DOWN_LEVEL(flags);
+    const int drop_level = GREMLIN_DROP_LEVEL(flags);
+
+    if (!initialized)
+    {
+        initialized = true;
+
+        if (up_down_level)
+        {
+            up = false;
+        }
+        else
+        {
+            up = true;
+        }
+
+        next = now;
+    }
+
+    if (up_down_level) /* change up/down state? */
+    {
+        if (now >= next)
+        {
+            int delta;
+            if (up)
+            {
+                delta = roll(down_low[up_down_level-1], down_high[up_down_level-1]);
+                up = false;
+            }
+            else
+            {
+                delta = roll(up_low[up_down_level-1], up_high[up_down_level-1]);
+                up = true;
+            }
+
+            msg(D_GREMLIN,
+                "GREMLIN: CONNECTION GOING %s FOR %d SECONDS",
+                (up ? "UP" : "DOWN"),
+                delta);
+            next = now + delta;
+        }
+    }
+
+    if (drop_level)
+    {
+        if (up && flip(drop_freq[drop_level-1]))
+        {
+            dmsg(D_GREMLIN_VERBOSE, "GREMLIN: Random packet drop");
+            return false;
+        }
+    }
+
+    return up;
+}
+
+/*
+ * Possibly corrupt a packet.
+ */
+void
+corrupt_gremlin(struct buffer *buf, int flags)
+{
+    const int corrupt_level = GREMLIN_CORRUPT_LEVEL(flags);
+    if (corrupt_level)
+    {
+        if (flip(corrupt_freq[corrupt_level-1]))
+        {
+            do
+            {
+                if (buf->len > 0)
+                {
+                    uint8_t r = roll(0, 255);
+                    int method = roll(0, 5);
+
+                    switch (method)
+                    {
+                        case 0: /* corrupt the first byte */
+                            *BPTR(buf) = r;
+                            break;
+
+                        case 1: /* corrupt the last byte */
+                            *(BPTR(buf) + buf->len - 1) = r;
+                            break;
+
+                        case 2: /* corrupt a random byte */
+                            *(BPTR(buf) + roll(0, buf->len - 1)) = r;
+                            break;
+
+                        case 3: /* append a random byte */
+                            buf_write(buf, &r, 1);
+                            break;
+
+                        case 4: /* reduce length by 1 */
+                            --buf->len;
+                            break;
+
+                        case 5: /* reduce length by a random amount */
+                            buf->len -= roll(0, buf->len - 1);
+                            break;
+                    }
+                    dmsg(D_GREMLIN_VERBOSE, "GREMLIN: Packet Corruption, method=%d", method);
+                }
+                else
+                {
+                    break;
+                }
+            } while (flip(2));  /* a 50% chance we will corrupt again */
+        }
+    }
+}
+
+#else  /* ifdef ENABLE_DEBUG */
+static void
+dummy(void)
+{
+}
+#endif /* ifdef ENABLE_DEBUG */
diff --git a/src/openvpn/gremlin.h b/src/openvpn/gremlin.h
new file mode 100644
index 0000000..22c90b9
--- /dev/null
+++ b/src/openvpn/gremlin.h
@@ -0,0 +1,73 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef GREMLIN_H
+#define GREMLIN_H
+
+#ifdef ENABLE_DEBUG
+
+/*
+ * Gremlin options, presented as bitmask argument to --gremlin directive
+ */
+
+#define GREMLIN_CONNECTION_FLOOD_SHIFT   (0)
+#define GREMLIN_CONNECTION_FLOOD_MASK    (0x07)
+
+#define GREMLIN_PACKET_FLOOD_SHIFT       (3)
+#define GREMLIN_PACKET_FLOOD_MASK        (0x03)
+
+#define GREMLIN_CORRUPT_SHIFT            (5)
+#define GREMLIN_CORRUPT_MASK             (0x03)
+
+#define GREMLIN_UP_DOWN_SHIFT            (7)
+#define GREMLIN_UP_DOWN_MASK             (0x03)
+
+/* 512:1/500 1024:1/100 1536:1/50 */
+
+#define GREMLIN_DROP_SHIFT               (9)
+#define GREMLIN_DROP_MASK                (0x03)
+
+/* extract gremlin parms */
+
+#define GREMLIN_CONNECTION_FLOOD_LEVEL(x) (((x)>>GREMLIN_CONNECTION_FLOOD_SHIFT) & GREMLIN_CONNECTION_FLOOD_MASK)
+#define GREMLIN_PACKET_FLOOD_LEVEL(x)     (((x)>>GREMLIN_PACKET_FLOOD_SHIFT)     & GREMLIN_PACKET_FLOOD_MASK)
+#define GREMLIN_CORRUPT_LEVEL(x)          (((x)>>GREMLIN_CORRUPT_SHIFT)          & GREMLIN_CORRUPT_MASK)
+#define GREMLIN_UP_DOWN_LEVEL(x)          (((x)>>GREMLIN_UP_DOWN_SHIFT)          & GREMLIN_UP_DOWN_MASK)
+#define GREMLIN_DROP_LEVEL(x)             (((x)>>GREMLIN_DROP_SHIFT)             & GREMLIN_DROP_MASK)
+
+#include "buffer.h"
+
+struct packet_flood_parms
+{
+    int n_packets;
+    int packet_size;
+};
+
+bool ask_gremlin(int flags);
+
+void corrupt_gremlin(struct buffer *buf, int flags);
+
+struct packet_flood_parms get_packet_flood_parms(int level);
+
+#endif /* ifdef ENABLE_DEBUG */
+#endif /* ifndef GREMLIN_H */
diff --git a/src/openvpn/helper.c b/src/openvpn/helper.c
new file mode 100644
index 0000000..ff9df50
--- /dev/null
+++ b/src/openvpn/helper.c
@@ -0,0 +1,590 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "forward.h"
+#include "helper.h"
+#include "pool.h"
+#include "push.h"
+
+#include "memdbg.h"
+
+#if P2MP_SERVER
+
+static const char *
+print_netmask(int netbits, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    const in_addr_t netmask = netbits_to_netmask(netbits);
+
+    buf_printf(&out, "%s (/%d)", print_in_addr_t(netmask, 0, gc), netbits);
+
+    return BSTR(&out);
+}
+
+static const char *
+print_opt_route_gateway(const in_addr_t route_gateway, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    ASSERT(route_gateway);
+    buf_printf(&out, "route-gateway %s", print_in_addr_t(route_gateway, 0, gc));
+    return BSTR(&out);
+}
+
+static const char *
+print_opt_route_gateway_dhcp(struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(32, gc);
+    buf_printf(&out, "route-gateway dhcp");
+    return BSTR(&out);
+}
+
+static const char *
+print_opt_route(const in_addr_t network, const in_addr_t netmask, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    ASSERT(network);
+
+    if (netmask)
+    {
+        buf_printf(&out, "route %s %s",
+                   print_in_addr_t(network, 0, gc),
+                   print_in_addr_t(netmask, 0, gc));
+    }
+    else
+    {
+        buf_printf(&out, "route %s",
+                   print_in_addr_t(network, 0, gc));
+    }
+
+    return BSTR(&out);
+}
+
+static const char *
+print_opt_topology(const int topology, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+
+    buf_printf(&out, "topology %s", print_topology(topology));
+
+    return BSTR(&out);
+}
+
+static const char *
+print_str_int(const char *str, const int i, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    buf_printf(&out, "%s %d", str, i);
+    return BSTR(&out);
+}
+
+static const char *
+print_str(const char *str, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    buf_printf(&out, "%s", str);
+    return BSTR(&out);
+}
+
+static void
+helper_add_route(const in_addr_t network, const in_addr_t netmask, struct options *o)
+{
+    rol_check_alloc(o);
+    add_route_to_option_list(o->routes,
+                             print_in_addr_t(network, 0, &o->gc),
+                             print_in_addr_t(netmask, 0, &o->gc),
+                             NULL,
+                             NULL);
+}
+
+static void
+verify_common_subnet(const char *opt, const in_addr_t a, const in_addr_t b, const in_addr_t subnet)
+{
+    struct gc_arena gc = gc_new();
+    if ((a & subnet) != (b & subnet))
+    {
+        msg(M_USAGE, "%s IP addresses %s and %s are not in the same %s subnet",
+            opt,
+            print_in_addr_t(a, 0, &gc),
+            print_in_addr_t(b, 0, &gc),
+            print_in_addr_t(subnet, 0, &gc));
+    }
+    gc_free(&gc);
+}
+
+#endif /* if P2MP_SERVER */
+
+/*
+ * Process server, server-bridge, and client helper
+ * directives after the parameters themselves have been
+ * parsed and placed in struct options.
+ */
+void
+helper_client_server(struct options *o)
+{
+    struct gc_arena gc = gc_new();
+
+#if P2MP
+#if P2MP_SERVER
+
+/*
+ * Get tun/tap/null device type
+ */
+    const int dev = dev_type_enum(o->dev, o->dev_type);
+    const int topology = o->topology;
+
+    /*
+     *
+     * HELPER DIRECTIVE for IPv6
+     *
+     * server-ipv6 2001:db8::/64
+     *
+     * EXPANDS TO:
+     *
+     * tun-ipv6
+     * push "tun-ipv6"
+     * ifconfig-ipv6 2001:db8::1 2001:db8::2
+     * if !nopool:
+     *   ifconfig-ipv6-pool 2001:db8::1000/64
+     *
+     */
+    if (o->server_ipv6_defined)
+    {
+        if (!o->server_defined)
+        {
+            msg(M_USAGE, "--server-ipv6 must be used together with --server");
+        }
+        if (o->server_flags & SF_NOPOOL)
+        {
+            msg( M_USAGE, "--server-ipv6 is incompatible with 'nopool' option" );
+        }
+        if (o->ifconfig_ipv6_pool_defined)
+        {
+            msg( M_USAGE, "--server-ipv6 already defines an ifconfig-ipv6-pool, so you can't also specify --ifconfig-pool explicitly");
+        }
+
+        /* local ifconfig is "base address + 1" and "+2" */
+        o->ifconfig_ipv6_local =
+            print_in6_addr( add_in6_addr( o->server_network_ipv6, 1), 0, &o->gc );
+        o->ifconfig_ipv6_remote =
+            print_in6_addr( add_in6_addr( o->server_network_ipv6, 2), 0, &o->gc );
+        o->ifconfig_ipv6_netbits = o->server_netbits_ipv6;
+
+        /* pool starts at "base address + 0x1000" - leave enough room */
+        ASSERT( o->server_netbits_ipv6 <= 112 );        /* want 16 bits */
+
+        o->ifconfig_ipv6_pool_defined = true;
+        o->ifconfig_ipv6_pool_base =
+            add_in6_addr( o->server_network_ipv6, 0x1000 );
+        o->ifconfig_ipv6_pool_netbits = o->server_netbits_ipv6;
+
+        push_option( o, "tun-ipv6", M_USAGE );
+    }
+
+    /*
+     *
+     * HELPER DIRECTIVE:
+     *
+     * server 10.8.0.0 255.255.255.0
+     *
+     * EXPANDS TO:
+     *
+     * mode server
+     * tls-server
+     * push "topology [topology]"
+     *
+     * if tun AND (topology == net30 OR topology == p2p):
+     *   ifconfig 10.8.0.1 10.8.0.2
+     *   if !nopool:
+     *     ifconfig-pool 10.8.0.4 10.8.0.251
+     *   route 10.8.0.0 255.255.255.0
+     *   if client-to-client:
+     *     push "route 10.8.0.0 255.255.255.0"
+     *   else if topology == net30:
+     *     push "route 10.8.0.1"
+     *
+     * if tap OR (tun AND topology == subnet):
+     *   ifconfig 10.8.0.1 255.255.255.0
+     *   if !nopool:
+     *     ifconfig-pool 10.8.0.2 10.8.0.253 255.255.255.0
+     *   push "route-gateway 10.8.0.1"
+     *   if route-gateway unset:
+     *     route-gateway 10.8.0.2
+     */
+
+    if (o->server_defined)
+    {
+        int netbits = -2;
+        bool status = false;
+
+        if (o->client)
+        {
+            msg(M_USAGE, "--server and --client cannot be used together");
+        }
+
+        if (o->server_bridge_defined || o->server_bridge_proxy_dhcp)
+        {
+            msg(M_USAGE, "--server and --server-bridge cannot be used together");
+        }
+
+        if (o->shared_secret_file)
+        {
+            msg(M_USAGE, "--server and --secret cannot be used together (you must use SSL/TLS keys)");
+        }
+
+        if (!(o->server_flags & SF_NOPOOL) && o->ifconfig_pool_defined)
+        {
+            msg(M_USAGE, "--server already defines an ifconfig-pool, so you can't also specify --ifconfig-pool explicitly");
+        }
+
+        if (!(dev == DEV_TYPE_TAP || dev == DEV_TYPE_TUN))
+        {
+            msg(M_USAGE, "--server directive only makes sense with --dev tun or --dev tap");
+        }
+
+        status = netmask_to_netbits(o->server_network, o->server_netmask, &netbits);
+        if (!status)
+        {
+            msg(M_USAGE, "--server directive network/netmask combination is invalid");
+        }
+
+        if (netbits < 0)
+        {
+            msg(M_USAGE, "--server directive netmask is invalid");
+        }
+
+        if (netbits < IFCONFIG_POOL_MIN_NETBITS)
+        {
+            msg(M_USAGE, "--server directive netmask allows for too many host addresses (subnet must be %s or higher)",
+                print_netmask(IFCONFIG_POOL_MIN_NETBITS, &gc));
+        }
+
+        if (dev == DEV_TYPE_TUN)
+        {
+            int pool_end_reserve = 4;
+
+            if (netbits > 29)
+            {
+                msg(M_USAGE, "--server directive when used with --dev tun must define a subnet of %s or lower",
+                    print_netmask(29, &gc));
+            }
+
+            if (netbits == 29)
+            {
+                pool_end_reserve = 0;
+            }
+
+            o->mode = MODE_SERVER;
+            o->tls_server = true;
+
+            if (topology == TOP_NET30 || topology == TOP_P2P)
+            {
+                o->ifconfig_local = print_in_addr_t(o->server_network + 1, 0, &o->gc);
+                o->ifconfig_remote_netmask = print_in_addr_t(o->server_network + 2, 0, &o->gc);
+
+                if (!(o->server_flags & SF_NOPOOL))
+                {
+                    o->ifconfig_pool_defined = true;
+                    o->ifconfig_pool_start = o->server_network + 4;
+                    o->ifconfig_pool_end = (o->server_network | ~o->server_netmask) - pool_end_reserve;
+                    ifconfig_pool_verify_range(M_USAGE, o->ifconfig_pool_start, o->ifconfig_pool_end);
+                }
+
+                helper_add_route(o->server_network, o->server_netmask, o);
+                if (o->enable_c2c)
+                {
+                    push_option(o, print_opt_route(o->server_network, o->server_netmask, &o->gc), M_USAGE);
+                }
+                else if (topology == TOP_NET30)
+                {
+                    push_option(o, print_opt_route(o->server_network + 1, 0, &o->gc), M_USAGE);
+                }
+            }
+            else if (topology == TOP_SUBNET)
+            {
+                o->ifconfig_local = print_in_addr_t(o->server_network + 1, 0, &o->gc);
+                o->ifconfig_remote_netmask = print_in_addr_t(o->server_netmask, 0, &o->gc);
+
+                if (!(o->server_flags & SF_NOPOOL))
+                {
+                    o->ifconfig_pool_defined = true;
+                    o->ifconfig_pool_start = o->server_network + 2;
+                    o->ifconfig_pool_end = (o->server_network | ~o->server_netmask) - 2;
+                    ifconfig_pool_verify_range(M_USAGE, o->ifconfig_pool_start, o->ifconfig_pool_end);
+                }
+                o->ifconfig_pool_netmask = o->server_netmask;
+
+                push_option(o, print_opt_route_gateway(o->server_network + 1, &o->gc), M_USAGE);
+                if (!o->route_default_gateway)
+                {
+                    o->route_default_gateway = print_in_addr_t(o->server_network + 2, 0, &o->gc);
+                }
+            }
+            else
+            {
+                ASSERT(0);
+            }
+
+            push_option(o, print_opt_topology(topology, &o->gc), M_USAGE);
+        }
+        else if (dev == DEV_TYPE_TAP)
+        {
+            if (netbits > 30)
+            {
+                msg(M_USAGE, "--server directive when used with --dev tap must define a subnet of %s or lower",
+                    print_netmask(30, &gc));
+            }
+
+            o->mode = MODE_SERVER;
+            o->tls_server = true;
+            o->ifconfig_local = print_in_addr_t(o->server_network + 1, 0, &o->gc);
+            o->ifconfig_remote_netmask = print_in_addr_t(o->server_netmask, 0, &o->gc);
+
+            if (!(o->server_flags & SF_NOPOOL))
+            {
+                o->ifconfig_pool_defined = true;
+                o->ifconfig_pool_start = o->server_network + 2;
+                o->ifconfig_pool_end = (o->server_network | ~o->server_netmask) - 1;
+                ifconfig_pool_verify_range(M_USAGE, o->ifconfig_pool_start, o->ifconfig_pool_end);
+            }
+            o->ifconfig_pool_netmask = o->server_netmask;
+
+            push_option(o, print_opt_route_gateway(o->server_network + 1, &o->gc), M_USAGE);
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        /* set push-ifconfig-constraint directive */
+        if ((dev == DEV_TYPE_TAP || topology == TOP_SUBNET))
+        {
+            o->push_ifconfig_constraint_defined = true;
+            o->push_ifconfig_constraint_network = o->server_network;
+            o->push_ifconfig_constraint_netmask = o->server_netmask;
+        }
+    }
+
+    /*
+     * HELPER DIRECTIVE:
+     *
+     * server-bridge 10.8.0.4 255.255.255.0 10.8.0.128 10.8.0.254
+     *
+     * EXPANDS TO:
+     *
+     * mode server
+     * tls-server
+     *
+     * ifconfig-pool 10.8.0.128 10.8.0.254 255.255.255.0
+     * push "route-gateway 10.8.0.4"
+     *
+     * OR
+     *
+     * server-bridge
+     *
+     * EXPANDS TO:
+     *
+     * mode server
+     * tls-server
+     *
+     * if !nogw:
+     *   push "route-gateway dhcp"
+     */
+    else if (o->server_bridge_defined | o->server_bridge_proxy_dhcp)
+    {
+        if (o->client)
+        {
+            msg(M_USAGE, "--server-bridge and --client cannot be used together");
+        }
+
+        if (!(o->server_flags & SF_NOPOOL) && o->ifconfig_pool_defined)
+        {
+            msg(M_USAGE, "--server-bridge already defines an ifconfig-pool, so you can't also specify --ifconfig-pool explicitly");
+        }
+
+        if (o->shared_secret_file)
+        {
+            msg(M_USAGE, "--server-bridge and --secret cannot be used together (you must use SSL/TLS keys)");
+        }
+
+        if (dev != DEV_TYPE_TAP)
+        {
+            msg(M_USAGE, "--server-bridge directive only makes sense with --dev tap");
+        }
+
+        if (o->server_bridge_defined)
+        {
+            verify_common_subnet("--server-bridge", o->server_bridge_ip, o->server_bridge_pool_start, o->server_bridge_netmask);
+            verify_common_subnet("--server-bridge", o->server_bridge_pool_start, o->server_bridge_pool_end, o->server_bridge_netmask);
+            verify_common_subnet("--server-bridge", o->server_bridge_ip, o->server_bridge_pool_end, o->server_bridge_netmask);
+        }
+
+        o->mode = MODE_SERVER;
+        o->tls_server = true;
+
+        if (o->server_bridge_defined)
+        {
+            o->ifconfig_pool_defined = true;
+            o->ifconfig_pool_start = o->server_bridge_pool_start;
+            o->ifconfig_pool_end = o->server_bridge_pool_end;
+            ifconfig_pool_verify_range(M_USAGE, o->ifconfig_pool_start, o->ifconfig_pool_end);
+            o->ifconfig_pool_netmask = o->server_bridge_netmask;
+            push_option(o, print_opt_route_gateway(o->server_bridge_ip, &o->gc), M_USAGE);
+        }
+        else if (o->server_bridge_proxy_dhcp && !(o->server_flags & SF_NO_PUSH_ROUTE_GATEWAY))
+        {
+            push_option(o, print_opt_route_gateway_dhcp(&o->gc), M_USAGE);
+        }
+    }
+    else
+#endif /* P2MP_SERVER */
+
+    /*
+     * HELPER DIRECTIVE:
+     *
+     * client
+     *
+     * EXPANDS TO:
+     *
+     * pull
+     * tls-client
+     */
+    if (o->client)
+    {
+        if (o->key_method != 2)
+        {
+            msg(M_USAGE, "--client requires --key-method 2");
+        }
+
+        o->pull = true;
+        o->tls_client = true;
+    }
+
+#endif /* P2MP */
+
+    gc_free(&gc);
+}
+
+/*
+ *
+ * HELPER DIRECTIVE:
+ *
+ * keepalive 10 60
+ *
+ * EXPANDS TO:
+ *
+ * if mode server:
+ *   ping 10
+ *   ping-restart 120
+ *   push "ping 10"
+ *   push "ping-restart 60"
+ * else
+ *   ping 10
+ *   ping-restart 60
+ */
+void
+helper_keepalive(struct options *o)
+{
+    if (o->keepalive_ping || o->keepalive_timeout)
+    {
+        /*
+         * Sanity checks.
+         */
+        if (o->keepalive_ping <= 0 || o->keepalive_timeout <= 0)
+        {
+            msg(M_USAGE, "--keepalive parameters must be > 0");
+        }
+        if (o->keepalive_ping * 2 > o->keepalive_timeout)
+        {
+            msg(M_USAGE, "the second parameter to --keepalive (restart timeout=%d) must be at least twice the value of the first parameter (ping interval=%d).  A ratio of 1:5 or 1:6 would be even better.  Recommended setting is --keepalive 10 60.",
+                o->keepalive_timeout,
+                o->keepalive_ping);
+        }
+        if (o->ping_send_timeout || o->ping_rec_timeout)
+        {
+            msg(M_USAGE, "--keepalive conflicts with --ping, --ping-exit, or --ping-restart.  If you use --keepalive, you don't need any of the other --ping directives.");
+        }
+
+        /*
+         * Expand.
+         */
+        if (o->mode == MODE_POINT_TO_POINT)
+        {
+            o->ping_rec_timeout_action = PING_RESTART;
+            o->ping_send_timeout = o->keepalive_ping;
+            o->ping_rec_timeout = o->keepalive_timeout;
+        }
+#if P2MP_SERVER
+        else if (o->mode == MODE_SERVER)
+        {
+            o->ping_rec_timeout_action = PING_RESTART;
+            o->ping_send_timeout = o->keepalive_ping;
+            o->ping_rec_timeout = o->keepalive_timeout * 2;
+            push_option(o, print_str_int("ping", o->keepalive_ping, &o->gc), M_USAGE);
+            push_option(o, print_str_int("ping-restart", o->keepalive_timeout, &o->gc), M_USAGE);
+        }
+#endif
+        else
+        {
+            ASSERT(0);
+        }
+    }
+}
+
+/*
+ *
+ * HELPER DIRECTIVE:
+ *
+ * tcp-nodelay
+ *
+ * EXPANDS TO:
+ *
+ * if mode server:
+ *   socket-flags TCP_NODELAY
+ *   push "socket-flags TCP_NODELAY"
+ */
+void
+helper_tcp_nodelay(struct options *o)
+{
+#if P2MP_SERVER
+    if (o->server_flags & SF_TCP_NODELAY_HELPER)
+    {
+        if (o->mode == MODE_SERVER)
+        {
+            o->sockflags |= SF_TCP_NODELAY;
+            push_option(o, print_str("socket-flags TCP_NODELAY", &o->gc), M_USAGE);
+        }
+        else
+        {
+            o->sockflags |= SF_TCP_NODELAY;
+        }
+    }
+#endif
+}
diff --git a/src/openvpn/helper.h b/src/openvpn/helper.h
new file mode 100644
index 0000000..866a398
--- /dev/null
+++ b/src/openvpn/helper.h
@@ -0,0 +1,39 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Process helper directives such as server, client, and keepalive.
+ */
+
+#ifndef HELPER_H
+#define HELPER_H
+
+#include "options.h"
+
+void helper_keepalive(struct options *o);
+
+void helper_client_server(struct options *o);
+
+void helper_tcp_nodelay(struct options *o);
+
+#endif
diff --git a/src/openvpn/httpdigest.c b/src/openvpn/httpdigest.c
new file mode 100644
index 0000000..7cf74fd
--- /dev/null
+++ b/src/openvpn/httpdigest.c
@@ -0,0 +1,164 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if PROXY_DIGEST_AUTH
+
+#include "crypto.h"
+#include "httpdigest.h"
+
+static void
+CvtHex(
+    IN HASH Bin,
+    OUT HASHHEX Hex
+    )
+{
+    unsigned short i;
+    unsigned char j;
+
+    for (i = 0; i < HASHLEN; i++)
+    {
+        j = (Bin[i] >> 4) & 0xf;
+        if (j <= 9)
+        {
+            Hex[i*2] = (j + '0');
+        }
+        else
+        {
+            Hex[i*2] = (j + 'a' - 10);
+        }
+        j = Bin[i] & 0xf;
+        if (j <= 9)
+        {
+            Hex[i*2+1] = (j + '0');
+        }
+        else
+        {
+            Hex[i*2+1] = (j + 'a' - 10);
+        }
+    }
+    Hex[HASHHEXLEN] = '\0';
+}
+
+/* calculate H(A1) as per spec */
+void
+DigestCalcHA1(
+    IN char *pszAlg,
+    IN char *pszUserName,
+    IN char *pszRealm,
+    IN char *pszPassword,
+    IN char *pszNonce,
+    IN char *pszCNonce,
+    OUT HASHHEX SessionKey
+    )
+{
+    HASH HA1;
+    md_ctx_t *md5_ctx = md_ctx_new();
+    const md_kt_t *md5_kt = md_kt_get("MD5");
+
+    md_ctx_init(md5_ctx, md5_kt);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszUserName, strlen(pszUserName));
+    md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszRealm, strlen(pszRealm));
+    md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszPassword, strlen(pszPassword));
+    md_ctx_final(md5_ctx, HA1);
+    if (pszAlg && strcasecmp(pszAlg, "md5-sess") == 0)
+    {
+        md_ctx_init(md5_ctx, md5_kt);
+        md_ctx_update(md5_ctx, HA1, HASHLEN);
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+        md_ctx_update(md5_ctx, (const uint8_t *) pszNonce, strlen(pszNonce));
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+        md_ctx_update(md5_ctx, (const uint8_t *) pszCNonce, strlen(pszCNonce));
+        md_ctx_final(md5_ctx, HA1);
+    }
+    md_ctx_cleanup(md5_ctx);
+    md_ctx_free(md5_ctx);
+    CvtHex(HA1, SessionKey);
+}
+
+/* calculate request-digest/response-digest as per HTTP Digest spec */
+void
+DigestCalcResponse(
+    IN HASHHEX HA1,                          /* H(A1) */
+    IN char *pszNonce,                       /* nonce from server */
+    IN char *pszNonceCount,                  /* 8 hex digits */
+    IN char *pszCNonce,                      /* client nonce */
+    IN char *pszQop,                         /* qop-value: "", "auth", "auth-int" */
+    IN char *pszMethod,                      /* method from the request */
+    IN char *pszDigestUri,                   /* requested URL */
+    IN HASHHEX HEntity,                      /* H(entity body) if qop="auth-int" */
+    OUT HASHHEX Response                     /* request-digest or response-digest */
+    )
+{
+    HASH HA2;
+    HASH RespHash;
+    HASHHEX HA2Hex;
+
+    md_ctx_t *md5_ctx = md_ctx_new();
+    const md_kt_t *md5_kt = md_kt_get("MD5");
+
+    /* calculate H(A2) */
+    md_ctx_init(md5_ctx, md5_kt);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszMethod, strlen(pszMethod));
+    md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszDigestUri, strlen(pszDigestUri));
+    if (strcasecmp(pszQop, "auth-int") == 0)
+    {
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+        md_ctx_update(md5_ctx, HEntity, HASHHEXLEN);
+    }
+    md_ctx_final(md5_ctx, HA2);
+    CvtHex(HA2, HA2Hex);
+
+    /* calculate response */
+    md_ctx_init(md5_ctx, md5_kt);
+    md_ctx_update(md5_ctx, HA1, HASHHEXLEN);
+    md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    md_ctx_update(md5_ctx, (const uint8_t *) pszNonce, strlen(pszNonce));
+    md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    if (*pszQop)
+    {
+        md_ctx_update(md5_ctx, (const uint8_t *) pszNonceCount, strlen(pszNonceCount));
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+        md_ctx_update(md5_ctx, (const uint8_t *) pszCNonce, strlen(pszCNonce));
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+        md_ctx_update(md5_ctx, (const uint8_t *) pszQop, strlen(pszQop));
+        md_ctx_update(md5_ctx, (const uint8_t *) ":", 1);
+    }
+    md_ctx_update(md5_ctx, HA2Hex, HASHHEXLEN);
+    md_ctx_final(md5_ctx, RespHash);
+    md_ctx_cleanup(md5_ctx);
+    md_ctx_free(md5_ctx);
+    CvtHex(RespHash, Response);
+}
+
+#endif /* if PROXY_DIGEST_AUTH */
diff --git a/src/openvpn/httpdigest.h b/src/openvpn/httpdigest.h
new file mode 100644
index 0000000..959220f
--- /dev/null
+++ b/src/openvpn/httpdigest.h
@@ -0,0 +1,59 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#if PROXY_DIGEST_AUTH
+
+#define HASHLEN 16
+typedef unsigned char HASH[HASHLEN];
+#define HASHHEXLEN 32
+typedef unsigned char HASHHEX[HASHHEXLEN+1];
+#undef IN
+#undef OUT
+#define IN const
+#define OUT
+
+/* calculate H(A1) as per HTTP Digest spec */
+void DigestCalcHA1(
+    IN char *pszAlg,
+    IN char *pszUserName,
+    IN char *pszRealm,
+    IN char *pszPassword,
+    IN char *pszNonce,
+    IN char *pszCNonce,
+    OUT HASHHEX SessionKey
+    );
+
+/* calculate request-digest/response-digest as per HTTP Digest spec */
+void DigestCalcResponse(
+    IN HASHHEX HA1,           /* H(A1) */
+    IN char *pszNonce,        /* nonce from server */
+    IN char *pszNonceCount,   /* 8 hex digits */
+    IN char *pszCNonce,       /* client nonce */
+    IN char *pszQop,          /* qop-value: "", "auth", "auth-int" */
+    IN char *pszMethod,       /* method from the request */
+    IN char *pszDigestUri,    /* requested URL */
+    IN HASHHEX HEntity,       /* H(entity body) if qop="auth-int" */
+    OUT HASHHEX Response      /* request-digest or response-digest */
+    );
+
+#endif /* if PROXY_DIGEST_AUTH */
diff --git a/src/openvpn/init.c b/src/openvpn/init.c
new file mode 100644
index 0000000..8bac74f
--- /dev/null
+++ b/src/openvpn/init.c
@@ -0,0 +1,4610 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_SYSTEMD
+#include <systemd/sd-daemon.h>
+#endif
+
+#include "win32.h"
+#include "init.h"
+#include "sig.h"
+#include "occ.h"
+#include "list.h"
+#include "otime.h"
+#include "pool.h"
+#include "gremlin.h"
+#include "pkcs11.h"
+#include "ps.h"
+#include "lladdr.h"
+#include "ping.h"
+#include "mstats.h"
+#include "ssl_verify.h"
+#include "tls_crypt.h"
+#include "forward-inline.h"
+
+#include "memdbg.h"
+
+#include "occ-inline.h"
+
+static struct context *static_context; /* GLOBAL */
+
+/*
+ * Crypto initialization flags
+ */
+#define CF_LOAD_PERSISTED_PACKET_ID (1<<0)
+#define CF_INIT_TLS_MULTI           (1<<1)
+#define CF_INIT_TLS_AUTH_STANDALONE (1<<2)
+
+static void do_init_first_time(struct context *c);
+
+void
+context_clear(struct context *c)
+{
+    CLEAR(*c);
+}
+
+void
+context_clear_1(struct context *c)
+{
+    CLEAR(c->c1);
+}
+
+void
+context_clear_2(struct context *c)
+{
+    CLEAR(c->c2);
+}
+
+void
+context_clear_all_except_first_time(struct context *c)
+{
+    const bool first_time_save = c->first_time;
+    const struct context_persist cpsave = c->persist;
+    context_clear(c);
+    c->first_time = first_time_save;
+    c->persist = cpsave;
+}
+
+/*
+ * Pass tunnel endpoint and MTU parms to a user-supplied script.
+ * Used to execute the up/down script/plugins.
+ */
+static void
+run_up_down(const char *command,
+            const struct plugin_list *plugins,
+            int plugin_type,
+            const char *arg,
+#ifdef _WIN32
+            DWORD adapter_index,
+#endif
+            const char *dev_type,
+            int tun_mtu,
+            int link_mtu,
+            const char *ifconfig_local,
+            const char *ifconfig_remote,
+            const char *context,
+            const char *signal_text,
+            const char *script_type,
+            struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+
+    if (signal_text)
+    {
+        setenv_str(es, "signal", signal_text);
+    }
+    setenv_str(es, "script_context", context);
+    setenv_int(es, "tun_mtu", tun_mtu);
+    setenv_int(es, "link_mtu", link_mtu);
+    setenv_str(es, "dev", arg);
+    if (dev_type)
+    {
+        setenv_str(es, "dev_type", dev_type);
+    }
+#ifdef _WIN32
+    setenv_int(es, "dev_idx", adapter_index);
+#endif
+
+    if (!ifconfig_local)
+    {
+        ifconfig_local = "";
+    }
+    if (!ifconfig_remote)
+    {
+        ifconfig_remote = "";
+    }
+    if (!context)
+    {
+        context = "";
+    }
+
+    if (plugin_defined(plugins, plugin_type))
+    {
+        struct argv argv = argv_new();
+        ASSERT(arg);
+        argv_printf(&argv,
+                    "%s %d %d %s %s %s",
+                    arg,
+                    tun_mtu, link_mtu,
+                    ifconfig_local, ifconfig_remote,
+                    context);
+
+        if (plugin_call(plugins, plugin_type, &argv, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            msg(M_FATAL, "ERROR: up/down plugin call failed");
+        }
+
+        argv_reset(&argv);
+    }
+
+    if (command)
+    {
+        struct argv argv = argv_new();
+        ASSERT(arg);
+        setenv_str(es, "script_type", script_type);
+        argv_parse_cmd(&argv, command);
+        argv_printf_cat(&argv, "%s %d %d %s %s %s", arg, tun_mtu, link_mtu,
+                        ifconfig_local, ifconfig_remote, context);
+        argv_msg(M_INFO, &argv);
+        openvpn_run_script(&argv, es, S_FATAL, "--up/--down");
+        argv_reset(&argv);
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Should be called after options->ce is modified at the top
+ * of a SIGUSR1 restart.
+ */
+static void
+update_options_ce_post(struct options *options)
+{
+#if P2MP
+    /*
+     * In pull mode, we usually import --ping/--ping-restart parameters from
+     * the server.  However we should also set an initial default --ping-restart
+     * for the period of time before we pull the --ping-restart parameter
+     * from the server.
+     */
+    if (options->pull
+        && options->ping_rec_timeout_action == PING_UNDEF
+        && proto_is_dgram(options->ce.proto))
+    {
+        options->ping_rec_timeout = PRE_PULL_INITIAL_PING_RESTART;
+        options->ping_rec_timeout_action = PING_RESTART;
+    }
+#endif
+}
+
+#ifdef ENABLE_MANAGEMENT
+static bool
+management_callback_proxy_cmd(void *arg, const char **p)
+{
+    struct context *c = arg;
+    struct connection_entry *ce = &c->options.ce;
+    struct gc_arena *gc = &c->c2.gc;
+    bool ret = false;
+
+    update_time();
+    if (streq(p[1], "NONE"))
+    {
+        ret = true;
+    }
+    else if (p[2] && p[3])
+    {
+        if (streq(p[1], "HTTP"))
+        {
+            struct http_proxy_options *ho;
+            if (ce->proto != PROTO_TCP && ce->proto != PROTO_TCP_CLIENT)
+            {
+                msg(M_WARN, "HTTP proxy support only works for TCP based connections");
+                return false;
+            }
+            ho = init_http_proxy_options_once(&ce->http_proxy_options, gc);
+            ho->server = string_alloc(p[2], gc);
+            ho->port = string_alloc(p[3], gc);
+            ho->auth_retry = (p[4] && streq(p[4], "nct") ? PAR_NCT : PAR_ALL);
+            ret = true;
+        }
+        else if (streq(p[1], "SOCKS"))
+        {
+            ce->socks_proxy_server = string_alloc(p[2], gc);
+            ce->socks_proxy_port = string_alloc(p[3], gc);
+            ret = true;
+        }
+    }
+    else
+    {
+        msg(M_WARN, "Bad proxy command");
+    }
+
+    ce->flags &= ~CE_MAN_QUERY_PROXY;
+
+    return ret;
+}
+
+static bool
+ce_management_query_proxy(struct context *c)
+{
+    const struct connection_list *l = c->options.connection_list;
+    struct connection_entry *ce = &c->options.ce;
+    struct gc_arena gc;
+    bool ret = true;
+
+    update_time();
+    if (management)
+    {
+        gc = gc_new();
+        {
+            struct buffer out = alloc_buf_gc(256, &gc);
+            buf_printf(&out, ">PROXY:%u,%s,%s", (l ? l->current : 0) + 1,
+                       (proto_is_udp(ce->proto) ? "UDP" : "TCP"), np(ce->remote));
+            management_notify_generic(management, BSTR(&out));
+        }
+        ce->flags |= CE_MAN_QUERY_PROXY;
+        while (ce->flags & CE_MAN_QUERY_PROXY)
+        {
+            management_event_loop_n_seconds(management, 1);
+            if (IS_SIG(c))
+            {
+                ret = false;
+                break;
+            }
+        }
+        gc_free(&gc);
+    }
+
+    return ret;
+}
+
+
+static bool
+management_callback_remote_cmd(void *arg, const char **p)
+{
+    struct context *c = (struct context *) arg;
+    struct connection_entry *ce = &c->options.ce;
+    int ret = false;
+    if (p[1] && ((ce->flags>>CE_MAN_QUERY_REMOTE_SHIFT)&CE_MAN_QUERY_REMOTE_MASK) == CE_MAN_QUERY_REMOTE_QUERY)
+    {
+        int flags = 0;
+        if (!strcmp(p[1], "ACCEPT"))
+        {
+            flags = CE_MAN_QUERY_REMOTE_ACCEPT;
+            ret = true;
+        }
+        else if (!strcmp(p[1], "SKIP"))
+        {
+            flags = CE_MAN_QUERY_REMOTE_SKIP;
+            ret = true;
+        }
+        else if (!strcmp(p[1], "MOD") && p[2] && p[3])
+        {
+            if (strlen(p[2]) < RH_HOST_LEN && strlen(p[3]) < RH_PORT_LEN)
+            {
+                struct remote_host_store *rhs = c->options.rh_store;
+                if (!rhs)
+                {
+                    ALLOC_OBJ_CLEAR_GC(rhs, struct remote_host_store, &c->options.gc);
+                    c->options.rh_store = rhs;
+                }
+                strncpynt(rhs->host, p[2], RH_HOST_LEN);
+                strncpynt(rhs->port, p[3], RH_PORT_LEN);
+
+                ce->remote = rhs->host;
+                ce->remote_port = rhs->port;
+                flags = CE_MAN_QUERY_REMOTE_MOD;
+                ret = true;
+            }
+        }
+        if (ret)
+        {
+            ce->flags &= ~(CE_MAN_QUERY_REMOTE_MASK<<CE_MAN_QUERY_REMOTE_SHIFT);
+            ce->flags |= ((flags&CE_MAN_QUERY_REMOTE_MASK)<<CE_MAN_QUERY_REMOTE_SHIFT);
+        }
+    }
+    return ret;
+}
+
+static bool
+ce_management_query_remote(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+    volatile struct connection_entry *ce = &c->options.ce;
+    int ce_changed = true; /* presume the connection entry will be changed */
+
+    update_time();
+    if (management)
+    {
+        struct buffer out = alloc_buf_gc(256, &gc);
+
+        buf_printf(&out, ">REMOTE:%s,%s,%s", np(ce->remote), ce->remote_port,
+                   proto2ascii(ce->proto, ce->af, false));
+        management_notify_generic(management, BSTR(&out));
+
+        ce->flags &= ~(CE_MAN_QUERY_REMOTE_MASK << CE_MAN_QUERY_REMOTE_SHIFT);
+        ce->flags |= (CE_MAN_QUERY_REMOTE_QUERY << CE_MAN_QUERY_REMOTE_SHIFT);
+        while (((ce->flags >> CE_MAN_QUERY_REMOTE_SHIFT)
+                & CE_MAN_QUERY_REMOTE_MASK) == CE_MAN_QUERY_REMOTE_QUERY)
+        {
+            management_event_loop_n_seconds(management, 1);
+            if (IS_SIG(c))
+            {
+                ce_changed = false; /* connection entry have not been set */
+                break;
+            }
+        }
+    }
+    gc_free(&gc);
+
+    if (ce_changed)
+    {
+        /* If it is likely a connection entry was modified,
+         * check what changed in the flags and that it was not skipped
+         */
+        const int flags = ((ce->flags >> CE_MAN_QUERY_REMOTE_SHIFT)
+                           & CE_MAN_QUERY_REMOTE_MASK);
+        ce_changed = (flags != CE_MAN_QUERY_REMOTE_SKIP);
+    }
+    return ce_changed;
+}
+#endif /* ENABLE_MANAGEMENT */
+
+/*
+ * Initialize and possibly randomize connection list.
+ */
+static void
+init_connection_list(struct context *c)
+{
+    struct connection_list *l = c->options.connection_list;
+
+    l->current = -1;
+    if (c->options.remote_random)
+    {
+        int i;
+        for (i = 0; i < l->len; ++i)
+        {
+            const int j = get_random() % l->len;
+            if (i != j)
+            {
+                struct connection_entry *tmp;
+                tmp = l->array[i];
+                l->array[i] = l->array[j];
+                l->array[j] = tmp;
+            }
+        }
+    }
+}
+
+/*
+ * Clear the remote address list
+ */
+static void
+clear_remote_addrlist(struct link_socket_addr *lsa, bool free)
+{
+    if (lsa->remote_list && free)
+    {
+        freeaddrinfo(lsa->remote_list);
+    }
+    lsa->remote_list = NULL;
+    lsa->current_remote = NULL;
+}
+
+/*
+ * Increment to next connection entry
+ */
+static void
+next_connection_entry(struct context *c)
+{
+    struct connection_list *l = c->options.connection_list;
+    bool ce_defined;
+    struct connection_entry *ce;
+    int n_cycles = 0;
+
+    do
+    {
+        ce_defined = true;
+        if (c->options.no_advance && l->current >= 0)
+        {
+            c->options.no_advance = false;
+        }
+        else
+        {
+            /* Check if there is another resolved address to try for
+             * the current connection */
+            if (c->c1.link_socket_addr.current_remote
+                && c->c1.link_socket_addr.current_remote->ai_next)
+            {
+                c->c1.link_socket_addr.current_remote =
+                    c->c1.link_socket_addr.current_remote->ai_next;
+            }
+            else
+            {
+                /* FIXME (schwabe) fix the persist-remote-ip option for real,
+                 * this is broken probably ever since connection lists and multiple
+                 * remote existed
+                 */
+                if (!c->options.persist_remote_ip)
+                {
+                    /* close_instance should have cleared the addrinfo objects */
+                    ASSERT(c->c1.link_socket_addr.current_remote == NULL);
+                    ASSERT(c->c1.link_socket_addr.remote_list == NULL);
+                }
+                else
+                {
+                    c->c1.link_socket_addr.current_remote =
+                        c->c1.link_socket_addr.remote_list;
+                }
+
+                /*
+                 * Increase the number of connection attempts
+                 * If this is connect-retry-max * size(l)
+                 * OpenVPN will quit
+                 */
+
+                c->options.unsuccessful_attempts++;
+
+                if (++l->current >= l->len)
+                {
+
+                    l->current = 0;
+                    if (++n_cycles >= 2)
+                    {
+                        msg(M_FATAL, "No usable connection profiles are present");
+                    }
+                }
+            }
+        }
+
+        ce = l->array[l->current];
+
+        if (ce->flags & CE_DISABLED)
+        {
+            ce_defined = false;
+        }
+
+        c->options.ce = *ce;
+#ifdef ENABLE_MANAGEMENT
+        if (ce_defined && management && management_query_remote_enabled(management))
+        {
+            /* allow management interface to override connection entry details */
+            ce_defined = ce_management_query_remote(c);
+            if (IS_SIG(c))
+            {
+                break;
+            }
+        }
+        else if (ce_defined && management && management_query_proxy_enabled(management))
+        {
+            ce_defined = ce_management_query_proxy(c);
+            if (IS_SIG(c))
+            {
+                break;
+            }
+        }
+#endif
+    } while (!ce_defined);
+
+    /* Check if this connection attempt would bring us over the limit */
+    if (c->options.connect_retry_max > 0
+        && c->options.unsuccessful_attempts > (l->len  * c->options.connect_retry_max))
+    {
+        msg(M_FATAL, "All connections have been connect-retry-max (%d) times unsuccessful, exiting",
+            c->options.connect_retry_max);
+    }
+    update_options_ce_post(&c->options);
+}
+
+/*
+ * Query for private key and auth-user-pass username/passwords
+ */
+void
+init_query_passwords(const struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    /* Certificate password input */
+    if (c->options.key_pass_file)
+    {
+        pem_password_setup(c->options.key_pass_file);
+    }
+#endif
+
+#if P2MP
+    /* Auth user/pass input */
+    if (c->options.auth_user_pass_file)
+    {
+#ifdef ENABLE_CLIENT_CR
+        auth_user_pass_setup(c->options.auth_user_pass_file, &c->options.sc_info);
+#else
+        auth_user_pass_setup(c->options.auth_user_pass_file, NULL);
+#endif
+    }
+#endif
+}
+
+/*
+ * Initialize/Uninitialize HTTP or SOCKS proxy
+ */
+
+static void
+uninit_proxy_dowork(struct context *c)
+{
+    if (c->c1.http_proxy_owned && c->c1.http_proxy)
+    {
+        http_proxy_close(c->c1.http_proxy);
+        c->c1.http_proxy = NULL;
+        c->c1.http_proxy_owned = false;
+    }
+    if (c->c1.socks_proxy_owned && c->c1.socks_proxy)
+    {
+        socks_proxy_close(c->c1.socks_proxy);
+        c->c1.socks_proxy = NULL;
+        c->c1.socks_proxy_owned = false;
+    }
+}
+
+static void
+init_proxy_dowork(struct context *c)
+{
+    bool did_http = false;
+
+    uninit_proxy_dowork(c);
+
+    if (c->options.ce.http_proxy_options)
+    {
+        /* Possible HTTP proxy user/pass input */
+        c->c1.http_proxy = http_proxy_new(c->options.ce.http_proxy_options);
+        if (c->c1.http_proxy)
+        {
+            did_http = true;
+            c->c1.http_proxy_owned = true;
+        }
+    }
+
+    if (!did_http && c->options.ce.socks_proxy_server)
+    {
+        c->c1.socks_proxy = socks_proxy_new(c->options.ce.socks_proxy_server,
+                                            c->options.ce.socks_proxy_port,
+                                            c->options.ce.socks_proxy_authfile);
+        if (c->c1.socks_proxy)
+        {
+            c->c1.socks_proxy_owned = true;
+        }
+    }
+}
+
+static void
+init_proxy(struct context *c)
+{
+    init_proxy_dowork(c);
+}
+
+static void
+uninit_proxy(struct context *c)
+{
+    uninit_proxy_dowork(c);
+}
+
+/*
+ * Saves the initial state of NCP-regotiable
+ * options into a storage which persists over SIGUSR1.
+ */
+static void
+save_ncp_options(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    c->c1.ciphername = c->options.ciphername;
+    c->c1.authname = c->options.authname;
+    c->c1.keysize = c->options.keysize;
+#endif
+}
+
+/* Restores NCP-negotiable options to original values */
+static void
+restore_ncp_options(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    c->options.ciphername = c->c1.ciphername;
+    c->options.authname = c->c1.authname;
+    c->options.keysize = c->c1.keysize;
+#endif
+}
+
+void
+context_init_1(struct context *c)
+{
+    context_clear_1(c);
+
+    packet_id_persist_init(&c->c1.pid_persist);
+
+    init_connection_list(c);
+
+    save_ncp_options(c);
+
+#if defined(ENABLE_PKCS11)
+    if (c->first_time)
+    {
+        int i;
+        pkcs11_initialize(true, c->options.pkcs11_pin_cache_period);
+        for (i = 0; i<MAX_PARMS && c->options.pkcs11_providers[i] != NULL; i++)
+        {
+            pkcs11_addProvider(c->options.pkcs11_providers[i], c->options.pkcs11_protected_authentication[i],
+                               c->options.pkcs11_private_mode[i], c->options.pkcs11_cert_private[i]);
+        }
+    }
+#endif
+
+#if 0 /* test get_user_pass with GET_USER_PASS_NEED_OK flag */
+    {
+        /*
+         * In the management interface, you can okay the request by entering "needok token-insertion-request ok"
+         */
+        struct user_pass up;
+        CLEAR(up);
+        strcpy(up.username, "Please insert your cryptographic token"); /* put the high-level message in up.username */
+        get_user_pass(&up, NULL, "token-insertion-request", GET_USER_PASS_MANAGEMENT|GET_USER_PASS_NEED_OK);
+        msg(M_INFO, "RET:%s", up.password); /* will return the third argument to management interface
+                                             * 'needok' command, usually 'ok' or 'cancel'. */
+    }
+#endif
+
+#ifdef ENABLE_SYSTEMD
+    /* We can report the PID via getpid() to systemd here as OpenVPN will not
+     * do any fork due to daemon() a future call.
+     * See possibly_become_daemon() [init.c] for more details.
+     */
+    sd_notifyf(0, "READY=1\nSTATUS=Pre-connection initialization successful\nMAINPID=%lu",
+               (unsigned long) getpid());
+#endif
+
+}
+
+void
+context_gc_free(struct context *c)
+{
+    gc_free(&c->c2.gc);
+    gc_free(&c->options.gc);
+    gc_free(&c->gc);
+}
+
+#if PORT_SHARE
+
+static void
+close_port_share(void)
+{
+    if (port_share)
+    {
+        port_share_close(port_share);
+        port_share = NULL;
+    }
+}
+
+static void
+init_port_share(struct context *c)
+{
+    if (!port_share && (c->options.port_share_host && c->options.port_share_port))
+    {
+        port_share = port_share_open(c->options.port_share_host,
+                                     c->options.port_share_port,
+                                     MAX_RW_SIZE_LINK(&c->c2.frame),
+                                     c->options.port_share_journal_dir);
+        if (port_share == NULL)
+        {
+            msg(M_FATAL, "Fatal error: Port sharing failed");
+        }
+    }
+}
+
+#endif /* if PORT_SHARE */
+
+
+bool
+init_static(void)
+{
+    /* configure_path (); */
+
+#if defined(ENABLE_CRYPTO) && defined(DMALLOC)
+    crypto_init_dmalloc();
+#endif
+
+
+    /*
+     * Initialize random number seed.  random() is only used
+     * when "weak" random numbers are acceptable.
+     * SSL library routines are always used when cryptographically
+     * strong random numbers are required.
+     */
+    struct timeval tv;
+    if (!gettimeofday(&tv, NULL))
+    {
+        const unsigned int seed = (unsigned int) tv.tv_sec ^ tv.tv_usec;
+        srandom(seed);
+    }
+
+    error_reset();              /* initialize error.c */
+    reset_check_status();       /* initialize status check code in socket.c */
+
+#ifdef _WIN32
+    init_win32();
+#endif
+
+#ifdef OPENVPN_DEBUG_COMMAND_LINE
+    {
+        int i;
+        for (i = 0; i < argc; ++i)
+        {
+            msg(M_INFO, "argv[%d] = '%s'", i, argv[i]);
+        }
+    }
+#endif
+
+    update_time();
+
+#ifdef ENABLE_CRYPTO
+    init_ssl_lib();
+
+    /* init PRNG used for IV generation */
+    /* When forking, copy this to more places in the code to avoid fork
+     * random-state predictability */
+    prng_init(NULL, 0);
+#endif
+
+#ifdef PID_TEST
+    packet_id_interactive_test();       /* test the sequence number code */
+    return false;
+#endif
+
+#ifdef SCHEDULE_TEST
+    schedule_test();
+    return false;
+#endif
+
+#ifdef LIST_TEST
+    list_test();
+    return false;
+#endif
+
+#ifdef IFCONFIG_POOL_TEST
+    ifconfig_pool_test(0x0A010004, 0x0A0100FF);
+    return false;
+#endif
+
+#ifdef CHARACTER_CLASS_DEBUG
+    character_class_debug();
+    return false;
+#endif
+
+#ifdef EXTRACT_X509_FIELD_TEST
+    extract_x509_field_test();
+    return false;
+#endif
+
+#ifdef TIME_TEST
+    time_test();
+    return false;
+#endif
+
+#ifdef TEST_GET_DEFAULT_GATEWAY
+    {
+        struct route_gateway_info rgi;
+        struct route_ipv6_gateway_info rgi6;
+        get_default_gateway(&rgi);
+        get_default_gateway_ipv6(&rgi6, NULL);
+        print_default_gateway(M_INFO, &rgi, &rgi6);
+        return false;
+    }
+#endif
+
+#ifdef GEN_PATH_TEST
+    {
+        struct gc_arena gc = gc_new();
+        const char *fn = gen_path("foo",
+                                  "bar",
+                                  &gc);
+        printf("%s\n", fn);
+        gc_free(&gc);
+    }
+    return false;
+#endif
+
+#ifdef STATUS_PRINTF_TEST
+    {
+        struct gc_arena gc = gc_new();
+        const char *tmp_file = create_temp_file("/tmp", "foo", &gc);
+        struct status_output *so = status_open(tmp_file, 0, -1, NULL, STATUS_OUTPUT_WRITE);
+        status_printf(so, "%s", "foo");
+        status_printf(so, "%s", "bar");
+        if (!status_close(so))
+        {
+            msg(M_WARN, "STATUS_PRINTF_TEST: %s: write error", tmp_file);
+        }
+        gc_free(&gc);
+    }
+    return false;
+#endif
+
+#ifdef ARGV_TEST
+    {
+        void argv_test(void);
+
+        argv_test();
+        return false;
+    }
+#endif
+
+#ifdef PRNG_TEST
+    {
+        struct gc_arena gc = gc_new();
+        uint8_t rndbuf[8];
+        int i;
+        prng_init("sha1", 16);
+        /*prng_init (NULL, 0);*/
+        const int factor = 1;
+        for (i = 0; i < factor * 8; ++i)
+        {
+#if 1
+            prng_bytes(rndbuf, sizeof(rndbuf));
+#else
+            ASSERT(rand_bytes(rndbuf, sizeof(rndbuf)));
+#endif
+            printf("[%d] %s\n", i, format_hex(rndbuf, sizeof(rndbuf), 0, &gc));
+        }
+        gc_free(&gc);
+        prng_uninit();
+        return false;
+    }
+#endif /* ifdef PRNG_TEST */
+
+#ifdef BUFFER_LIST_AGGREGATE_TEST
+    /* test buffer_list_aggregate function */
+    {
+        static const char *text[] = {
+            "It was a bright cold day in April, ",
+            "and the clocks were striking ",
+            "thirteen. ",
+            "Winston Smith, ",
+            "his chin nuzzled into his breast in an ",
+            "effort to escape the vile wind, ",
+            "slipped quickly through the glass doors ",
+            "of Victory Mansions, though not quickly ",
+            "enough to prevent a swirl of gritty dust from ",
+            "entering along with him."
+        };
+
+        int iter, listcap;
+        for (listcap = 0; listcap < 12; ++listcap)
+        {
+            for (iter = 0; iter < 512; ++iter)
+            {
+                struct buffer_list *bl = buffer_list_new(listcap);
+                {
+                    int i;
+                    for (i = 0; i < SIZE(text); ++i)
+                    {
+                        buffer_list_push(bl, (unsigned char *)text[i]);
+                    }
+                }
+                printf("[cap=%d i=%d] *************************\n", listcap, iter);
+                if (!(iter & 8))
+                {
+                    buffer_list_aggregate(bl, iter/2);
+                }
+                if (!(iter & 16))
+                {
+                    buffer_list_push(bl, (unsigned char *)"Even more text...");
+                }
+                buffer_list_aggregate(bl, iter);
+                if (!(iter & 1))
+                {
+                    buffer_list_push(bl, (unsigned char *)"More text...");
+                }
+                {
+                    struct buffer *buf;
+                    while ((buf = buffer_list_peek(bl)))
+                    {
+                        int c;
+                        printf("'");
+                        while ((c = buf_read_u8(buf)) >= 0)
+                        {
+                            putchar(c);
+                        }
+                        printf("'\n");
+                        buffer_list_advance(bl, 0);
+                    }
+                }
+                buffer_list_free(bl);
+            }
+        }
+        return false;
+    }
+#endif /* ifdef BUFFER_LIST_AGGREGATE_TEST */
+
+#ifdef MSTATS_TEST
+    {
+        int i;
+        mstats_open("/dev/shm/mstats.dat");
+        for (i = 0; i < 30; ++i)
+        {
+            mmap_stats->n_clients += 1;
+            mmap_stats->link_write_bytes += 8;
+            mmap_stats->link_read_bytes += 16;
+            sleep(1);
+        }
+        mstats_close();
+        return false;
+    }
+#endif
+
+    return true;
+}
+
+void
+uninit_static(void)
+{
+#ifdef ENABLE_CRYPTO
+    free_ssl_lib();
+#endif
+
+#ifdef ENABLE_PKCS11
+    pkcs11_terminate();
+#endif
+
+#if PORT_SHARE
+    close_port_share();
+#endif
+
+#if defined(MEASURE_TLS_HANDSHAKE_STATS) && defined(ENABLE_CRYPTO)
+    show_tls_performance_stats();
+#endif
+}
+
+void
+init_verb_mute(struct context *c, unsigned int flags)
+{
+    if (flags & IVM_LEVEL_1)
+    {
+        /* set verbosity and mute levels */
+        set_check_status(D_LINK_ERRORS, D_READ_WRITE);
+        set_debug_level(c->options.verbosity, SDL_CONSTRAIN);
+        set_mute_cutoff(c->options.mute);
+    }
+
+    /* special D_LOG_RW mode */
+    if (flags & IVM_LEVEL_2)
+    {
+        c->c2.log_rw = (check_debug_level(D_LOG_RW) && !check_debug_level(D_LOG_RW + 1));
+    }
+}
+
+/*
+ * Possibly set --dev based on --dev-node.
+ * For example, if --dev-node /tmp/foo/tun, and --dev undefined,
+ * set --dev to tun.
+ */
+void
+init_options_dev(struct options *options)
+{
+    if (!options->dev && options->dev_node)
+    {
+        char *dev_node = string_alloc(options->dev_node, NULL); /* POSIX basename() implementaions may modify its arguments */
+        options->dev = basename(dev_node);
+    }
+}
+
+bool
+print_openssl_info(const struct options *options)
+{
+    /*
+     * OpenSSL info print mode?
+     */
+#ifdef ENABLE_CRYPTO
+    if (options->show_ciphers || options->show_digests || options->show_engines
+        || options->show_tls_ciphers || options->show_curves)
+    {
+        if (options->show_ciphers)
+        {
+            show_available_ciphers();
+        }
+        if (options->show_digests)
+        {
+            show_available_digests();
+        }
+        if (options->show_engines)
+        {
+            show_available_engines();
+        }
+        if (options->show_tls_ciphers)
+        {
+            show_available_tls_ciphers(options->cipher_list,
+                                       options->cipher_list_tls13,
+                                       options->tls_cert_profile);
+        }
+        if (options->show_curves)
+        {
+            show_available_curves();
+        }
+        return true;
+    }
+#endif /* ifdef ENABLE_CRYPTO */
+    return false;
+}
+
+/*
+ * Static pre-shared key generation mode?
+ */
+bool
+do_genkey(const struct options *options)
+{
+#ifdef ENABLE_CRYPTO
+    if (options->genkey)
+    {
+        int nbits_written;
+
+        notnull(options->shared_secret_file,
+                "shared secret output file (--secret)");
+
+        if (options->mlock)     /* should we disable paging? */
+        {
+            platform_mlockall(true);
+        }
+
+        nbits_written = write_key_file(2, options->shared_secret_file);
+
+        msg(D_GENKEY | M_NOPREFIX,
+            "Randomly generated %d bit key written to %s", nbits_written,
+            options->shared_secret_file);
+        return true;
+    }
+#endif
+    return false;
+}
+
+/*
+ * Persistent TUN/TAP device management mode?
+ */
+bool
+do_persist_tuntap(const struct options *options)
+{
+    if (options->persist_config)
+    {
+        /* sanity check on options for --mktun or --rmtun */
+        notnull(options->dev, "TUN/TAP device (--dev)");
+        if (options->ce.remote || options->ifconfig_local
+            || options->ifconfig_remote_netmask
+#ifdef ENABLE_CRYPTO
+            || options->shared_secret_file
+            || options->tls_server || options->tls_client
+#endif
+            )
+        {
+            msg(M_FATAL|M_OPTERR,
+                "options --mktun or --rmtun should only be used together with --dev");
+        }
+#ifdef ENABLE_FEATURE_TUN_PERSIST
+        tuncfg(options->dev, options->dev_type, options->dev_node,
+               options->persist_mode,
+               options->username, options->groupname, &options->tuntap_options);
+        if (options->persist_mode && options->lladdr)
+        {
+            set_lladdr(options->dev, options->lladdr, NULL);
+        }
+        return true;
+#else  /* ifdef ENABLE_FEATURE_TUN_PERSIST */
+        msg( M_FATAL|M_OPTERR,
+             "options --mktun and --rmtun are not available on your operating "
+             "system.  Please check 'man tun' (or 'tap'), whether your system "
+             "supports using 'ifconfig %s create' / 'destroy' to create/remove "
+             "persistant tunnel interfaces.", options->dev );
+#endif
+    }
+    return false;
+}
+
+/*
+ * Should we become a daemon?
+ * Return true if we did it.
+ */
+bool
+possibly_become_daemon(const struct options *options)
+{
+    bool ret = false;
+
+#ifdef ENABLE_SYSTEMD
+    /* return without forking if we are running from systemd */
+    if (sd_notify(0, "READY=0") > 0)
+    {
+        return ret;
+    }
+#endif
+
+    if (options->daemon)
+    {
+        ASSERT(!options->inetd);
+        /* Don't chdir immediately, but the end of the init sequence, if needed */
+        if (daemon(1, options->log) < 0)
+        {
+            msg(M_ERR, "daemon() failed or unsupported");
+        }
+        restore_signal_state();
+        if (options->log)
+        {
+            set_std_files_to_null(true);
+        }
+
+        ret = true;
+    }
+    return ret;
+}
+
+/*
+ * Actually do UID/GID downgrade, chroot and SELinux context switching, if requested.
+ */
+static void
+do_uid_gid_chroot(struct context *c, bool no_delay)
+{
+    static const char why_not[] = "will be delayed because of --client, --pull, or --up-delay";
+    struct context_0 *c0 = c->c0;
+
+    if (c0 && !c0->uid_gid_chroot_set)
+    {
+        /* chroot if requested */
+        if (c->options.chroot_dir)
+        {
+            if (no_delay)
+            {
+                platform_chroot(c->options.chroot_dir);
+            }
+            else if (c->first_time)
+            {
+                msg(M_INFO, "NOTE: chroot %s", why_not);
+            }
+        }
+
+        /* set user and/or group if we want to setuid/setgid */
+        if (c0->uid_gid_specified)
+        {
+            if (no_delay)
+            {
+                platform_group_set(&c0->platform_state_group);
+                platform_user_set(&c0->platform_state_user);
+            }
+            else if (c->first_time)
+            {
+                msg(M_INFO, "NOTE: UID/GID downgrade %s", why_not);
+            }
+        }
+
+#ifdef ENABLE_MEMSTATS
+        if (c->first_time && c->options.memstats_fn)
+        {
+            mstats_open(c->options.memstats_fn);
+        }
+#endif
+
+#ifdef ENABLE_SELINUX
+        /* Apply a SELinux context in order to restrict what OpenVPN can do
+         * to _only_ what it is supposed to do after initialization is complete
+         * (basically just network I/O operations). Doing it after chroot
+         * requires /proc to be mounted in the chroot (which is annoying indeed
+         * but doing it before requires more complex SELinux policies.
+         */
+        if (c->options.selinux_context)
+        {
+            if (no_delay)
+            {
+                if (-1 == setcon(c->options.selinux_context))
+                {
+                    msg(M_ERR, "setcon to '%s' failed; is /proc accessible?", c->options.selinux_context);
+                }
+                else
+                {
+                    msg(M_INFO, "setcon to '%s' succeeded", c->options.selinux_context);
+                }
+            }
+            else if (c->first_time)
+            {
+                msg(M_INFO, "NOTE: setcon %s", why_not);
+            }
+        }
+#endif
+
+        /* Privileges are going to be dropped by now (if requested), be sure
+         * to prevent any future privilege dropping attempts from now on.
+         */
+        if (no_delay)
+        {
+            c0->uid_gid_chroot_set = true;
+        }
+    }
+}
+
+/*
+ * Return common name in a way that is formatted for
+ * prepending to msg() output.
+ */
+const char *
+format_common_name(struct context *c, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+#ifdef ENABLE_CRYPTO
+    if (c->c2.tls_multi)
+    {
+        buf_printf(&out, "[%s] ", tls_common_name(c->c2.tls_multi, false));
+    }
+#endif
+    return BSTR(&out);
+}
+
+void
+pre_setup(const struct options *options)
+{
+#ifdef _WIN32
+    if (options->exit_event_name)
+    {
+        win32_signal_open(&win32_signal,
+                          WSO_FORCE_SERVICE,
+                          options->exit_event_name,
+                          options->exit_event_initial_state);
+    }
+    else
+    {
+        win32_signal_open(&win32_signal,
+                          WSO_FORCE_CONSOLE,
+                          NULL,
+                          false);
+
+        /* put a title on the top window bar */
+        if (win32_signal.mode == WSO_MODE_CONSOLE)
+        {
+            window_title_save(&window_title);
+            window_title_generate(options->config);
+        }
+    }
+#endif /* ifdef _WIN32 */
+}
+
+void
+reset_coarse_timers(struct context *c)
+{
+    c->c2.coarse_timer_wakeup = 0;
+}
+
+/*
+ * Initialise the server poll timeout timer
+ * This timer is used in the http/socks proxy setup so it needs to be setup
+ * before
+ */
+static void
+do_init_server_poll_timeout(struct context *c)
+{
+    update_time();
+    if (c->options.ce.connect_timeout)
+    {
+        event_timeout_init(&c->c2.server_poll_interval, c->options.ce.connect_timeout, now);
+    }
+}
+
+/*
+ * Initialize timers
+ */
+static void
+do_init_timers(struct context *c, bool deferred)
+{
+    update_time();
+    reset_coarse_timers(c);
+
+    /* initialize inactivity timeout */
+    if (c->options.inactivity_timeout)
+    {
+        event_timeout_init(&c->c2.inactivity_interval, c->options.inactivity_timeout, now);
+    }
+
+    /* initialize pings */
+
+    if (c->options.ping_send_timeout)
+    {
+        event_timeout_init(&c->c2.ping_send_interval, c->options.ping_send_timeout, 0);
+    }
+
+    if (c->options.ping_rec_timeout)
+    {
+        event_timeout_init(&c->c2.ping_rec_interval, c->options.ping_rec_timeout, now);
+    }
+
+    if (!deferred)
+    {
+        /* initialize connection establishment timer */
+        event_timeout_init(&c->c2.wait_for_connect, 1, now);
+
+#ifdef ENABLE_OCC
+        /* initialize occ timers */
+
+        if (c->options.occ
+            && !TLS_MODE(c)
+            && c->c2.options_string_local && c->c2.options_string_remote)
+        {
+            event_timeout_init(&c->c2.occ_interval, OCC_INTERVAL_SECONDS, now);
+        }
+
+        if (c->options.mtu_test)
+        {
+            event_timeout_init(&c->c2.occ_mtu_load_test_interval, OCC_MTU_LOAD_INTERVAL_SECONDS, now);
+        }
+#endif
+
+        /* initialize packet_id persistence timer */
+#ifdef ENABLE_CRYPTO
+        if (c->options.packet_id_file)
+        {
+            event_timeout_init(&c->c2.packet_id_persist_interval, 60, now);
+        }
+
+        /* initialize tmp_int optimization that limits the number of times we call
+         * tls_multi_process in the main event loop */
+        interval_init(&c->c2.tmp_int, TLS_MULTI_HORIZON, TLS_MULTI_REFRESH);
+#endif
+    }
+}
+
+/*
+ * Initialize traffic shaper.
+ */
+static void
+do_init_traffic_shaper(struct context *c)
+{
+#ifdef ENABLE_FEATURE_SHAPER
+    /* initialize traffic shaper (i.e. transmit bandwidth limiter) */
+    if (c->options.shaper)
+    {
+        shaper_init(&c->c2.shaper, c->options.shaper);
+        shaper_msg(&c->c2.shaper);
+    }
+#endif
+}
+
+/*
+ * Allocate route list structures for IPv4 and IPv6
+ * (we do this for IPv4 even if no --route option has been seen, as other
+ * parts of OpenVPN might want to fill the route-list with info, e.g. DHCP)
+ */
+static void
+do_alloc_route_list(struct context *c)
+{
+    if (!c->c1.route_list)
+    {
+        ALLOC_OBJ_CLEAR_GC(c->c1.route_list, struct route_list, &c->gc);
+    }
+    if (c->options.routes_ipv6 && !c->c1.route_ipv6_list)
+    {
+        ALLOC_OBJ_CLEAR_GC(c->c1.route_ipv6_list, struct route_ipv6_list, &c->gc);
+    }
+}
+
+
+/*
+ * Initialize the route list, resolving any DNS names in route
+ * options and saving routes in the environment.
+ */
+static void
+do_init_route_list(const struct options *options,
+                   struct route_list *route_list,
+                   const struct link_socket_info *link_socket_info,
+                   struct env_set *es)
+{
+    const char *gw = NULL;
+    int dev = dev_type_enum(options->dev, options->dev_type);
+    int metric = 0;
+
+    if (dev == DEV_TYPE_TUN && (options->topology == TOP_NET30 || options->topology == TOP_P2P))
+    {
+        gw = options->ifconfig_remote_netmask;
+    }
+    if (options->route_default_gateway)
+    {
+        gw = options->route_default_gateway;
+    }
+    if (options->route_default_metric)
+    {
+        metric = options->route_default_metric;
+    }
+
+    if (init_route_list(route_list,
+                        options->routes,
+                        gw,
+                        metric,
+                        link_socket_current_remote(link_socket_info),
+                        es))
+    {
+        /* copy routes to environment */
+        setenv_routes(es, route_list);
+    }
+}
+
+static void
+do_init_route_ipv6_list(const struct options *options,
+                        struct route_ipv6_list *route_ipv6_list,
+                        const struct link_socket_info *link_socket_info,
+                        struct env_set *es)
+{
+    const char *gw = NULL;
+    int metric = -1;            /* no metric set */
+
+    gw = options->ifconfig_ipv6_remote;         /* default GW = remote end */
+#if 0                                   /* not yet done for IPv6 - TODO!*/
+    if (options->route_ipv6_default_gateway)            /* override? */
+    {
+        gw = options->route_ipv6_default_gateway;
+    }
+#endif
+
+    if (options->route_default_metric)
+    {
+        metric = options->route_default_metric;
+    }
+
+    /* redirect (IPv6) gateway to VPN?  if yes, add a few more specifics
+     */
+    if (options->routes_ipv6->flags & RG_REROUTE_GW)
+    {
+        char *opt_list[] = { "::/3", "2000::/4", "3000::/4", "fc00::/7", NULL };
+        int i;
+
+        for (i = 0; opt_list[i]; i++)
+        {
+            add_route_ipv6_to_option_list( options->routes_ipv6,
+                                           string_alloc(opt_list[i], options->routes_ipv6->gc),
+                                           NULL, NULL );
+        }
+    }
+
+    if (init_route_ipv6_list(route_ipv6_list,
+                             options->routes_ipv6,
+                             gw,
+                             metric,
+                             link_socket_current_remote_ipv6(link_socket_info),
+                             es))
+    {
+        /* copy routes to environment */
+        setenv_routes_ipv6(es, route_ipv6_list);
+    }
+}
+
+
+/*
+ * Called after all initialization has been completed.
+ */
+void
+initialization_sequence_completed(struct context *c, const unsigned int flags)
+{
+    static const char message[] = "Initialization Sequence Completed";
+
+    /* Reset the unsuccessful connection counter on complete initialisation */
+    c->options.unsuccessful_attempts = 0;
+
+    /* If we delayed UID/GID downgrade or chroot, do it now */
+    do_uid_gid_chroot(c, true);
+
+
+#ifdef ENABLE_CRYPTO
+    /*
+     * In some cases (i.e. when receiving auth-token via
+     * push-reply) the auth-nocache option configured on the
+     * client is overridden; for this reason we have to wait
+     * for the push-reply message before attempting to wipe
+     * the user/pass entered by the user
+     */
+    if (c->options.mode == MODE_POINT_TO_POINT)
+    {
+        delayed_auth_pass_purge();
+    }
+#endif /* ENABLE_CRYPTO */
+
+    /* Test if errors */
+    if (flags & ISC_ERRORS)
+    {
+#ifdef _WIN32
+        show_routes(M_INFO|M_NOPREFIX);
+        show_adapters(M_INFO|M_NOPREFIX);
+        msg(M_INFO, "%s With Errors ( see http://openvpn.net/faq.html#dhcpclientserv )", message);
+#else
+#ifdef ENABLE_SYSTEMD
+        sd_notifyf(0, "STATUS=Failed to start up: %s With Errors\nERRNO=1", message);
+#endif /* HAVE_SYSTEMD_SD_DAEMON_H */
+        msg(M_INFO, "%s With Errors", message);
+#endif
+    }
+    else
+    {
+#ifdef ENABLE_SYSTEMD
+        sd_notifyf(0, "STATUS=%s", message);
+#endif
+        msg(M_INFO, "%s", message);
+    }
+
+    /* Flag that we initialized */
+    if ((flags & (ISC_ERRORS|ISC_SERVER)) == 0)
+    {
+        c->options.no_advance = true;
+    }
+
+#ifdef _WIN32
+    fork_register_dns_action(c->c1.tuntap);
+#endif
+
+#ifdef ENABLE_MANAGEMENT
+    /* Tell management interface that we initialized */
+    if (management)
+    {
+        in_addr_t *tun_local = NULL;
+        struct in6_addr *tun_local6 = NULL;
+        struct openvpn_sockaddr local, remote;
+        struct link_socket_actual *actual;
+        socklen_t sa_len = sizeof(local);
+        const char *detail = "SUCCESS";
+        if (flags & ISC_ERRORS)
+        {
+            detail = "ERROR";
+        }
+
+        CLEAR(local);
+        actual = &get_link_socket_info(c)->lsa->actual;
+        remote = actual->dest;
+        getsockname(c->c2.link_socket->sd, &local.addr.sa, &sa_len);
+#if ENABLE_IP_PKTINFO
+        if (!addr_defined(&local))
+        {
+            switch (local.addr.sa.sa_family)
+            {
+                case AF_INET:
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+                    local.addr.in4.sin_addr = actual->pi.in4.ipi_spec_dst;
+#else
+                    local.addr.in4.sin_addr = actual->pi.in4;
+#endif
+                    break;
+
+                case AF_INET6:
+                    local.addr.in6.sin6_addr = actual->pi.in6.ipi6_addr;
+                    break;
+            }
+        }
+#endif
+
+        if (c->c1.tuntap)
+        {
+            tun_local = &c->c1.tuntap->local;
+            tun_local6 = &c->c1.tuntap->local_ipv6;
+        }
+        management_set_state(management,
+                             OPENVPN_STATE_CONNECTED,
+                             detail,
+                             tun_local,
+                             tun_local6,
+                             &local,
+                             &remote);
+        if (tun_local)
+        {
+            management_post_tunnel_open(management, *tun_local);
+        }
+    }
+#endif /* ifdef ENABLE_MANAGEMENT */
+}
+
+/*
+ * Possibly add routes and/or call route-up script
+ * based on options.
+ */
+void
+do_route(const struct options *options,
+         struct route_list *route_list,
+         struct route_ipv6_list *route_ipv6_list,
+         const struct tuntap *tt,
+         const struct plugin_list *plugins,
+         struct env_set *es)
+{
+    if (!options->route_noexec && ( route_list || route_ipv6_list ) )
+    {
+        add_routes(route_list, route_ipv6_list, tt, ROUTE_OPTION_FLAGS(options), es);
+        setenv_int(es, "redirect_gateway", route_did_redirect_default_gateway(route_list));
+    }
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        management_up_down(management, "UP", es);
+    }
+#endif
+
+    if (plugin_defined(plugins, OPENVPN_PLUGIN_ROUTE_UP))
+    {
+        if (plugin_call(plugins, OPENVPN_PLUGIN_ROUTE_UP, NULL, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            msg(M_WARN, "WARNING: route-up plugin call failed");
+        }
+    }
+
+    if (options->route_script)
+    {
+        struct argv argv = argv_new();
+        setenv_str(es, "script_type", "route-up");
+        argv_parse_cmd(&argv, options->route_script);
+        openvpn_run_script(&argv, es, 0, "--route-up");
+        argv_reset(&argv);
+    }
+
+#ifdef _WIN32
+    if (options->show_net_up)
+    {
+        show_routes(M_INFO|M_NOPREFIX);
+        show_adapters(M_INFO|M_NOPREFIX);
+    }
+    else if (check_debug_level(D_SHOW_NET))
+    {
+        show_routes(D_SHOW_NET|M_NOPREFIX);
+        show_adapters(D_SHOW_NET|M_NOPREFIX);
+    }
+#endif
+}
+
+/*
+ * initialize tun/tap device object
+ */
+static void
+do_init_tun(struct context *c)
+{
+    c->c1.tuntap = init_tun(c->options.dev,
+                            c->options.dev_type,
+                            c->options.topology,
+                            c->options.ifconfig_local,
+                            c->options.ifconfig_remote_netmask,
+                            c->options.ifconfig_ipv6_local,
+                            c->options.ifconfig_ipv6_netbits,
+                            c->options.ifconfig_ipv6_remote,
+                            c->c1.link_socket_addr.bind_local,
+                            c->c1.link_socket_addr.remote_list,
+                            !c->options.ifconfig_nowarn,
+                            c->c2.es);
+
+    init_tun_post(c->c1.tuntap,
+                  &c->c2.frame,
+                  &c->options.tuntap_options);
+
+    c->c1.tuntap_owned = true;
+}
+
+/*
+ * Open tun/tap device, ifconfig, call up script, etc.
+ */
+
+static bool
+do_open_tun(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+#ifndef TARGET_ANDROID
+    if (!c->c1.tuntap)
+    {
+#endif
+
+#ifdef TARGET_ANDROID
+    /* If we emulate persist-tun on android we still have to open a new tun and
+     * then close the old */
+    int oldtunfd = -1;
+    if (c->c1.tuntap)
+    {
+        oldtunfd = c->c1.tuntap->fd;
+        free(c->c1.tuntap);
+        c->c1.tuntap = NULL;
+        c->c1.tuntap_owned = false;
+    }
+#endif
+
+    /* initialize (but do not open) tun/tap object */
+    do_init_tun(c);
+
+#ifdef _WIN32
+    /* store (hide) interactive service handle in tuntap_options */
+    c->c1.tuntap->options.msg_channel = c->options.msg_channel;
+    msg(D_ROUTE, "interactive service msg_channel=%u", (unsigned int) c->options.msg_channel);
+#endif
+
+    /* allocate route list structure */
+    do_alloc_route_list(c);
+
+    /* parse and resolve the route option list */
+    ASSERT(c->c2.link_socket);
+    if (c->options.routes && c->c1.route_list)
+    {
+        do_init_route_list(&c->options, c->c1.route_list,
+                           &c->c2.link_socket->info, c->c2.es);
+    }
+    if (c->options.routes_ipv6 && c->c1.route_ipv6_list)
+    {
+        do_init_route_ipv6_list(&c->options, c->c1.route_ipv6_list,
+                                &c->c2.link_socket->info, c->c2.es);
+    }
+
+    /* do ifconfig */
+    if (!c->options.ifconfig_noexec
+        && ifconfig_order() == IFCONFIG_BEFORE_TUN_OPEN)
+    {
+        /* guess actual tun/tap unit number that will be returned
+         * by open_tun */
+        const char *guess = guess_tuntap_dev(c->options.dev,
+                                             c->options.dev_type,
+                                             c->options.dev_node,
+                                             &gc);
+        do_ifconfig(c->c1.tuntap, guess, TUN_MTU_SIZE(&c->c2.frame), c->c2.es);
+    }
+
+    /* possibly add routes */
+    if (route_order() == ROUTE_BEFORE_TUN)
+    {
+        /* Ignore route_delay, would cause ROUTE_BEFORE_TUN to be ignored */
+        do_route(&c->options, c->c1.route_list, c->c1.route_ipv6_list,
+                 c->c1.tuntap, c->plugins, c->c2.es);
+    }
+#ifdef TARGET_ANDROID
+    /* Store the old fd inside the fd so open_tun can use it */
+    c->c1.tuntap->fd = oldtunfd;
+#endif
+    /* open the tun device */
+    open_tun(c->options.dev, c->options.dev_type, c->options.dev_node,
+             c->c1.tuntap);
+
+    /* set the hardware address */
+    if (c->options.lladdr)
+    {
+        set_lladdr(c->c1.tuntap->actual_name, c->options.lladdr, c->c2.es);
+    }
+
+    /* do ifconfig */
+    if (!c->options.ifconfig_noexec
+        && ifconfig_order() == IFCONFIG_AFTER_TUN_OPEN)
+    {
+        do_ifconfig(c->c1.tuntap, c->c1.tuntap->actual_name, TUN_MTU_SIZE(&c->c2.frame), c->c2.es);
+    }
+
+    /* run the up script */
+    run_up_down(c->options.up_script,
+                c->plugins,
+                OPENVPN_PLUGIN_UP,
+                c->c1.tuntap->actual_name,
+#ifdef _WIN32
+                c->c1.tuntap->adapter_index,
+#endif
+                dev_type_string(c->options.dev, c->options.dev_type),
+                TUN_MTU_SIZE(&c->c2.frame),
+                EXPANDED_SIZE(&c->c2.frame),
+                print_in_addr_t(c->c1.tuntap->local, IA_EMPTY_IF_UNDEF, &gc),
+                print_in_addr_t(c->c1.tuntap->remote_netmask, IA_EMPTY_IF_UNDEF, &gc),
+                "init",
+                NULL,
+                "up",
+                c->c2.es);
+
+#if defined(_WIN32)
+    if (c->options.block_outside_dns)
+    {
+        dmsg(D_LOW, "Blocking outside DNS");
+        if (!win_wfp_block_dns(c->c1.tuntap->adapter_index, c->options.msg_channel))
+        {
+            msg(M_FATAL, "Blocking DNS failed!");
+        }
+    }
+#endif
+
+    /* possibly add routes */
+    if ((route_order() == ROUTE_AFTER_TUN) && (!c->options.route_delay_defined))
+    {
+        do_route(&c->options, c->c1.route_list, c->c1.route_ipv6_list,
+                 c->c1.tuntap, c->plugins, c->c2.es);
+    }
+
+    /*
+     * Did tun/tap driver give us an MTU?
+     */
+    if (c->c1.tuntap->post_open_mtu)
+    {
+        frame_set_mtu_dynamic(&c->c2.frame,
+                              c->c1.tuntap->post_open_mtu,
+                              SET_MTU_TUN | SET_MTU_UPPER_BOUND);
+    }
+
+    ret = true;
+    static_context = c;
+#ifndef TARGET_ANDROID
+}
+else
+{
+    msg(M_INFO, "Preserving previous TUN/TAP instance: %s",
+        c->c1.tuntap->actual_name);
+
+    /* explicitly set the ifconfig_* env vars */
+    do_ifconfig_setenv(c->c1.tuntap, c->c2.es);
+
+    /* run the up script if user specified --up-restart */
+    if (c->options.up_restart)
+    {
+        run_up_down(c->options.up_script,
+                    c->plugins,
+                    OPENVPN_PLUGIN_UP,
+                    c->c1.tuntap->actual_name,
+#ifdef _WIN32
+                    c->c1.tuntap->adapter_index,
+#endif
+                    dev_type_string(c->options.dev, c->options.dev_type),
+                    TUN_MTU_SIZE(&c->c2.frame),
+                    EXPANDED_SIZE(&c->c2.frame),
+                    print_in_addr_t(c->c1.tuntap->local, IA_EMPTY_IF_UNDEF, &gc),
+                    print_in_addr_t(c->c1.tuntap->remote_netmask, IA_EMPTY_IF_UNDEF, &gc),
+                    "restart",
+                    NULL,
+                    "up",
+                    c->c2.es);
+    }
+#if defined(_WIN32)
+    if (c->options.block_outside_dns)
+    {
+        dmsg(D_LOW, "Blocking outside DNS");
+        if (!win_wfp_block_dns(c->c1.tuntap->adapter_index, c->options.msg_channel))
+        {
+            msg(M_FATAL, "Blocking DNS failed!");
+        }
+    }
+#endif
+
+}
+#endif /* ifndef TARGET_ANDROID */
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Close TUN/TAP device
+ */
+
+static void
+do_close_tun_simple(struct context *c)
+{
+    msg(D_CLOSE, "Closing TUN/TAP interface");
+    close_tun(c->c1.tuntap);
+    c->c1.tuntap = NULL;
+    c->c1.tuntap_owned = false;
+#if P2MP
+    CLEAR(c->c1.pulled_options_digest_save);
+#endif
+}
+
+static void
+do_close_tun(struct context *c, bool force)
+{
+    struct gc_arena gc = gc_new();
+    if (c->c1.tuntap && c->c1.tuntap_owned)
+    {
+        const char *tuntap_actual = string_alloc(c->c1.tuntap->actual_name, &gc);
+#ifdef _WIN32
+        DWORD adapter_index = c->c1.tuntap->adapter_index;
+#endif
+        const in_addr_t local = c->c1.tuntap->local;
+        const in_addr_t remote_netmask = c->c1.tuntap->remote_netmask;
+
+        if (force || !(c->sig->signal_received == SIGUSR1 && c->options.persist_tun))
+        {
+            static_context = NULL;
+
+#ifdef ENABLE_MANAGEMENT
+            /* tell management layer we are about to close the TUN/TAP device */
+            if (management)
+            {
+                management_pre_tunnel_close(management);
+                management_up_down(management, "DOWN", c->c2.es);
+            }
+#endif
+
+            /* delete any routes we added */
+            if (c->c1.route_list || c->c1.route_ipv6_list)
+            {
+                run_up_down(c->options.route_predown_script,
+                            c->plugins,
+                            OPENVPN_PLUGIN_ROUTE_PREDOWN,
+                            tuntap_actual,
+#ifdef _WIN32
+                            adapter_index,
+#endif
+                            NULL,
+                            TUN_MTU_SIZE(&c->c2.frame),
+                            EXPANDED_SIZE(&c->c2.frame),
+                            print_in_addr_t(local, IA_EMPTY_IF_UNDEF, &gc),
+                            print_in_addr_t(remote_netmask, IA_EMPTY_IF_UNDEF, &gc),
+                            "init",
+                            signal_description(c->sig->signal_received,
+                                               c->sig->signal_text),
+                            "route-pre-down",
+                            c->c2.es);
+
+                delete_routes(c->c1.route_list, c->c1.route_ipv6_list,
+                              c->c1.tuntap, ROUTE_OPTION_FLAGS(&c->options), c->c2.es);
+            }
+
+            /* actually close tun/tap device based on --down-pre flag */
+            if (!c->options.down_pre)
+            {
+                do_close_tun_simple(c);
+            }
+
+            /* Run the down script -- note that it will run at reduced
+             * privilege if, for example, "--user nobody" was used. */
+            run_up_down(c->options.down_script,
+                        c->plugins,
+                        OPENVPN_PLUGIN_DOWN,
+                        tuntap_actual,
+#ifdef _WIN32
+                        adapter_index,
+#endif
+                        NULL,
+                        TUN_MTU_SIZE(&c->c2.frame),
+                        EXPANDED_SIZE(&c->c2.frame),
+                        print_in_addr_t(local, IA_EMPTY_IF_UNDEF, &gc),
+                        print_in_addr_t(remote_netmask, IA_EMPTY_IF_UNDEF, &gc),
+                        "init",
+                        signal_description(c->sig->signal_received,
+                                           c->sig->signal_text),
+                        "down",
+                        c->c2.es);
+
+#if defined(_WIN32)
+            if (c->options.block_outside_dns)
+            {
+                if (!win_wfp_uninit(adapter_index, c->options.msg_channel))
+                {
+                    msg(M_FATAL, "Uninitialising WFP failed!");
+                }
+            }
+#endif
+
+            /* actually close tun/tap device based on --down-pre flag */
+            if (c->options.down_pre)
+            {
+                do_close_tun_simple(c);
+            }
+        }
+        else
+        {
+            /* run the down script on this restart if --up-restart was specified */
+            if (c->options.up_restart)
+            {
+                run_up_down(c->options.down_script,
+                            c->plugins,
+                            OPENVPN_PLUGIN_DOWN,
+                            tuntap_actual,
+#ifdef _WIN32
+                            adapter_index,
+#endif
+                            NULL,
+                            TUN_MTU_SIZE(&c->c2.frame),
+                            EXPANDED_SIZE(&c->c2.frame),
+                            print_in_addr_t(local, IA_EMPTY_IF_UNDEF, &gc),
+                            print_in_addr_t(remote_netmask, IA_EMPTY_IF_UNDEF, &gc),
+                            "restart",
+                            signal_description(c->sig->signal_received,
+                                               c->sig->signal_text),
+                            "down",
+                            c->c2.es);
+            }
+
+#if defined(_WIN32)
+            if (c->options.block_outside_dns)
+            {
+                if (!win_wfp_uninit(adapter_index, c->options.msg_channel))
+                {
+                    msg(M_FATAL, "Uninitialising WFP failed!");
+                }
+            }
+#endif
+
+        }
+    }
+    gc_free(&gc);
+}
+
+void
+tun_abort(void)
+{
+    struct context *c = static_context;
+    if (c)
+    {
+        static_context = NULL;
+        do_close_tun(c, true);
+    }
+}
+
+/*
+ * Handle delayed tun/tap interface bringup due to --up-delay or --pull
+ */
+
+#if P2MP
+/**
+ * Helper for do_up().  Take two option hashes and return true if they are not
+ * equal, or either one is all-zeroes.
+ */
+static bool
+options_hash_changed_or_zero(const struct sha256_digest *a,
+                             const struct sha256_digest *b)
+{
+    const struct sha256_digest zero = {{0}};
+    return memcmp(a, b, sizeof(struct sha256_digest))
+           || !memcmp(a, &zero, sizeof(struct sha256_digest));
+}
+#endif /* P2MP */
+
+bool
+do_up(struct context *c, bool pulled_options, unsigned int option_types_found)
+{
+    if (!c->c2.do_up_ran)
+    {
+        reset_coarse_timers(c);
+
+        if (pulled_options)
+        {
+            if (!do_deferred_options(c, option_types_found))
+            {
+                msg(D_PUSH_ERRORS, "ERROR: Failed to apply push options");
+                return false;
+            }
+        }
+
+        /* if --up-delay specified, open tun, do ifconfig, and run up script now */
+        if (c->options.up_delay || PULL_DEFINED(&c->options))
+        {
+            c->c2.did_open_tun = do_open_tun(c);
+            update_time();
+
+#if P2MP
+            /*
+             * Was tun interface object persisted from previous restart iteration,
+             * and if so did pulled options string change from previous iteration?
+             */
+            if (!c->c2.did_open_tun
+                && PULL_DEFINED(&c->options)
+                && c->c1.tuntap
+                && options_hash_changed_or_zero(&c->c1.pulled_options_digest_save,
+                                                &c->c2.pulled_options_digest))
+            {
+                /* if so, close tun, delete routes, then reinitialize tun and add routes */
+                msg(M_INFO, "NOTE: Pulled options changed on restart, will need to close and reopen TUN/TAP device.");
+                do_close_tun(c, true);
+                management_sleep(1);
+                c->c2.did_open_tun = do_open_tun(c);
+                update_time();
+            }
+#endif
+        }
+
+        if (c->c2.did_open_tun)
+        {
+#if P2MP
+            c->c1.pulled_options_digest_save = c->c2.pulled_options_digest;
+#endif
+
+            /* if --route-delay was specified, start timer */
+            if ((route_order() == ROUTE_AFTER_TUN) && c->options.route_delay_defined)
+            {
+                event_timeout_init(&c->c2.route_wakeup, c->options.route_delay, now);
+                event_timeout_init(&c->c2.route_wakeup_expire, c->options.route_delay + c->options.route_delay_window, now);
+                if (c->c1.tuntap)
+                {
+                    tun_standby_init(c->c1.tuntap);
+                }
+            }
+            else
+            {
+                initialization_sequence_completed(c, 0); /* client/p2p --route-delay undefined */
+            }
+        }
+        else if (c->options.mode == MODE_POINT_TO_POINT)
+        {
+            initialization_sequence_completed(c, 0); /* client/p2p restart with --persist-tun */
+        }
+
+        c->c2.do_up_ran = true;
+    }
+    return true;
+}
+
+/*
+ * These are the option categories which will be accepted by pull.
+ */
+unsigned int
+pull_permission_mask(const struct context *c)
+{
+    unsigned int flags =
+        OPT_P_UP
+        | OPT_P_ROUTE_EXTRAS
+        | OPT_P_SOCKBUF
+        | OPT_P_SOCKFLAGS
+        | OPT_P_SETENV
+        | OPT_P_SHAPER
+        | OPT_P_TIMER
+        | OPT_P_COMP
+        | OPT_P_PERSIST
+        | OPT_P_MESSAGES
+        | OPT_P_EXPLICIT_NOTIFY
+        | OPT_P_ECHO
+        | OPT_P_PULL_MODE
+        | OPT_P_PEER_ID;
+
+    if (!c->options.route_nopull)
+    {
+        flags |= (OPT_P_ROUTE | OPT_P_IPWIN32);
+    }
+
+#ifdef ENABLE_CRYPTO
+    if (c->options.ncp_enabled)
+    {
+        flags |= OPT_P_NCP;
+    }
+#endif
+
+    return flags;
+}
+
+/*
+ * Handle non-tun-related pulled options.
+ */
+bool
+do_deferred_options(struct context *c, const unsigned int found)
+{
+    if (found & OPT_P_MESSAGES)
+    {
+        init_verb_mute(c, IVM_LEVEL_1|IVM_LEVEL_2);
+        msg(D_PUSH, "OPTIONS IMPORT: --verb and/or --mute level changed");
+    }
+    if (found & OPT_P_TIMER)
+    {
+        do_init_timers(c, true);
+        msg(D_PUSH, "OPTIONS IMPORT: timers and/or timeouts modified");
+    }
+
+#ifdef ENABLE_OCC
+    if (found & OPT_P_EXPLICIT_NOTIFY)
+    {
+        if (!proto_is_udp(c->options.ce.proto) && c->options.ce.explicit_exit_notification)
+        {
+            msg(D_PUSH, "OPTIONS IMPORT: --explicit-exit-notify can only be used with --proto udp");
+            c->options.ce.explicit_exit_notification = 0;
+        }
+        else
+        {
+            msg(D_PUSH, "OPTIONS IMPORT: explicit notify parm(s) modified");
+        }
+    }
+#endif
+
+#ifdef USE_COMP
+    if (found & OPT_P_COMP)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: compression parms modified");
+        comp_uninit(c->c2.comp_context);
+        c->c2.comp_context = comp_init(&c->options.comp);
+    }
+#endif
+
+    if (found & OPT_P_SHAPER)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: traffic shaper enabled");
+        do_init_traffic_shaper(c);
+    }
+
+    if (found & OPT_P_SOCKBUF)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: --sndbuf/--rcvbuf options modified");
+        link_socket_update_buffer_sizes(c->c2.link_socket, c->options.rcvbuf, c->options.sndbuf);
+    }
+
+    if (found & OPT_P_SOCKFLAGS)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: --socket-flags option modified");
+        link_socket_update_flags(c->c2.link_socket, c->options.sockflags);
+    }
+
+    if (found & OPT_P_PERSIST)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: --persist options modified");
+    }
+    if (found & OPT_P_UP)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: --ifconfig/up options modified");
+    }
+    if (found & OPT_P_ROUTE)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: route options modified");
+    }
+    if (found & OPT_P_ROUTE_EXTRAS)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: route-related options modified");
+    }
+    if (found & OPT_P_IPWIN32)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: --ip-win32 and/or --dhcp-option options modified");
+    }
+    if (found & OPT_P_SETENV)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: environment modified");
+    }
+
+#ifdef ENABLE_CRYPTO
+    if (found & OPT_P_PEER_ID)
+    {
+        msg(D_PUSH, "OPTIONS IMPORT: peer-id set");
+        c->c2.tls_multi->use_peer_id = true;
+        c->c2.tls_multi->peer_id = c->options.peer_id;
+        frame_add_to_extra_frame(&c->c2.frame, +3);     /* peer-id overhead */
+        if (!c->options.ce.link_mtu_defined)
+        {
+            frame_add_to_link_mtu(&c->c2.frame, +3);
+            msg(D_PUSH, "OPTIONS IMPORT: adjusting link_mtu to %d",
+                EXPANDED_SIZE(&c->c2.frame));
+        }
+        else
+        {
+            msg(M_WARN, "OPTIONS IMPORT: WARNING: peer-id set, but link-mtu"
+                " fixed by config - reducing tun-mtu to %d, expect"
+                " MTU problems", TUN_MTU_SIZE(&c->c2.frame) );
+        }
+    }
+
+    /* process (potentially pushed) crypto options */
+    if (c->options.pull)
+    {
+        struct tls_session *session = &c->c2.tls_multi->session[TM_ACTIVE];
+        if (found & OPT_P_NCP)
+        {
+            msg(D_PUSH, "OPTIONS IMPORT: data channel crypto options modified");
+        }
+        else if (c->options.ncp_enabled)
+        {
+            tls_poor_mans_ncp(&c->options, c->c2.tls_multi->remote_ciphername);
+        }
+        struct frame *frame_fragment = NULL;
+#ifdef ENABLE_FRAGMENT
+        if (c->options.ce.fragment)
+        {
+            frame_fragment = &c->c2.frame_fragment;
+        }
+#endif
+
+        if (!tls_session_update_crypto_params(session, &c->options, &c->c2.frame,
+                                              frame_fragment))
+        {
+            msg(D_TLS_ERRORS, "OPTIONS ERROR: failed to import crypto options");
+            return false;
+        }
+    }
+#endif /* ifdef ENABLE_CRYPTO */
+    return true;
+}
+
+/*
+ * Possible hold on initialization, holdtime is the
+ * time OpenVPN would wait without management
+ */
+static bool
+do_hold(int holdtime)
+{
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        /* block until management hold is released */
+        if (management_hold(management, holdtime))
+        {
+            return true;
+        }
+    }
+#endif
+    return false;
+}
+
+/*
+ * Sleep before restart.
+ */
+static void
+socket_restart_pause(struct context *c)
+{
+    int sec = 2;
+    int backoff = 0;
+
+    switch (c->options.ce.proto)
+    {
+        case PROTO_TCP_SERVER:
+            sec = 1;
+            break;
+
+        case PROTO_UDP:
+        case PROTO_TCP_CLIENT:
+            sec = c->options.ce.connect_retry_seconds;
+            break;
+    }
+
+#ifdef ENABLE_DEBUG
+    if (GREMLIN_CONNECTION_FLOOD_LEVEL(c->options.gremlin))
+    {
+        sec = 0;
+    }
+#endif
+
+#if P2MP
+    if (auth_retry_get() == AR_NOINTERACT)
+    {
+        sec = 10;
+    }
+#endif
+
+    /* Slow down reconnection after 5 retries per remote -- for tcp only in client mode */
+    if (c->options.ce.proto != PROTO_TCP_SERVER)
+    {
+        backoff = (c->options.unsuccessful_attempts / c->options.connection_list->len) - 4;
+        if (backoff > 0)
+        {
+            /* sec is less than 2^16; we can left shift it by up to 15 bits without overflow */
+            sec = max_int(sec, 1) << min_int(backoff, 15);
+        }
+
+        if (sec > c->options.ce.connect_retry_seconds_max)
+        {
+            sec = c->options.ce.connect_retry_seconds_max;
+        }
+    }
+
+    if (c->persist.restart_sleep_seconds > 0 && c->persist.restart_sleep_seconds > sec)
+    {
+        sec = c->persist.restart_sleep_seconds;
+    }
+    else if (c->persist.restart_sleep_seconds == -1)
+    {
+        sec = 0;
+    }
+    c->persist.restart_sleep_seconds = 0;
+
+    /* do managment hold on context restart, i.e. second, third, fourth, etc. initialization */
+    if (do_hold(sec))
+    {
+        sec = 0;
+    }
+
+    if (sec)
+    {
+        msg(D_RESTART, "Restart pause, %d second(s)", sec);
+        management_sleep(sec);
+    }
+}
+
+/*
+ * Do a possible pause on context_2 initialization.
+ */
+static void
+do_startup_pause(struct context *c)
+{
+    if (!c->first_time)
+    {
+        socket_restart_pause(c);
+    }
+    else
+    {
+        do_hold(0); /* do management hold on first context initialization */
+    }
+}
+
+/*
+ * Finalize MTU parameters based on command line or config file options.
+ */
+static void
+frame_finalize_options(struct context *c, const struct options *o)
+{
+    if (!o)
+    {
+        o = &c->options;
+    }
+
+    /*
+     * Set adjustment factor for buffer alignment when no
+     * cipher is used.
+     */
+    if (!CIPHER_ENABLED(c))
+    {
+        frame_align_to_extra_frame(&c->c2.frame);
+        frame_or_align_flags(&c->c2.frame,
+                             FRAME_HEADROOM_MARKER_FRAGMENT
+                             |FRAME_HEADROOM_MARKER_READ_LINK
+                             |FRAME_HEADROOM_MARKER_READ_STREAM);
+    }
+
+    frame_add_to_extra_buffer(&c->c2.frame, PAYLOAD_ALIGN);
+    frame_finalize(&c->c2.frame,
+                   o->ce.link_mtu_defined,
+                   o->ce.link_mtu,
+                   o->ce.tun_mtu_defined,
+                   o->ce.tun_mtu);
+}
+
+/*
+ * Free a key schedule, including OpenSSL components.
+ */
+static void
+key_schedule_free(struct key_schedule *ks, bool free_ssl_ctx)
+{
+#ifdef ENABLE_CRYPTO
+    free_key_ctx_bi(&ks->static_key);
+    if (tls_ctx_initialised(&ks->ssl_ctx) && free_ssl_ctx)
+    {
+        tls_ctx_free(&ks->ssl_ctx);
+        free_key_ctx_bi(&ks->tls_wrap_key);
+    }
+#endif /* ENABLE_CRYPTO */
+    CLEAR(*ks);
+}
+
+#ifdef ENABLE_CRYPTO
+
+static void
+init_crypto_pre(struct context *c, const unsigned int flags)
+{
+    if (c->options.engine)
+    {
+        crypto_init_lib_engine(c->options.engine);
+    }
+
+    if (flags & CF_LOAD_PERSISTED_PACKET_ID)
+    {
+        /* load a persisted packet-id for cross-session replay-protection */
+        if (c->options.packet_id_file)
+        {
+            packet_id_persist_load(&c->c1.pid_persist, c->options.packet_id_file);
+        }
+    }
+
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    if (c->options.use_prediction_resistance)
+    {
+        rand_ctx_enable_prediction_resistance();
+    }
+#endif
+
+}
+
+/*
+ * Static Key Mode (using a pre-shared key)
+ */
+static void
+do_init_crypto_static(struct context *c, const unsigned int flags)
+{
+    const struct options *options = &c->options;
+    ASSERT(options->shared_secret_file);
+
+    init_crypto_pre(c, flags);
+
+    /* Initialize flags */
+    if (c->options.use_iv)
+    {
+        c->c2.crypto_options.flags |= CO_USE_IV;
+    }
+
+    if (c->options.mute_replay_warnings)
+    {
+        c->c2.crypto_options.flags |= CO_MUTE_REPLAY_WARNINGS;
+    }
+
+    /* Initialize packet ID tracking */
+    if (options->replay)
+    {
+        packet_id_init(&c->c2.crypto_options.packet_id,
+                       options->replay_window,
+                       options->replay_time,
+                       "STATIC", 0);
+        c->c2.crypto_options.pid_persist = &c->c1.pid_persist;
+        c->c2.crypto_options.flags |= CO_PACKET_ID_LONG_FORM;
+        packet_id_persist_load_obj(&c->c1.pid_persist,
+                                   &c->c2.crypto_options.packet_id);
+    }
+
+    if (!key_ctx_bi_defined(&c->c1.ks.static_key))
+    {
+        /* Get cipher & hash algorithms */
+        init_key_type(&c->c1.ks.key_type, options->ciphername, options->authname,
+                      options->keysize, options->test_crypto, true);
+
+        /* Read cipher and hmac keys from shared secret file */
+        crypto_read_openvpn_key(&c->c1.ks.key_type, &c->c1.ks.static_key,
+                                options->shared_secret_file,
+                                options->shared_secret_file_inline,
+                                options->key_direction, "Static Key Encryption",
+                                "secret");
+    }
+    else
+    {
+        msg(M_INFO, "Re-using pre-shared static key");
+    }
+
+    /* Get key schedule */
+    c->c2.crypto_options.key_ctx_bi = c->c1.ks.static_key;
+
+    /* Compute MTU parameters */
+    crypto_adjust_frame_parameters(&c->c2.frame,
+                                   &c->c1.ks.key_type,
+                                   options->use_iv, options->replay, true);
+
+    /* Sanity check on IV, sequence number, and cipher mode options */
+    check_replay_iv_consistency(&c->c1.ks.key_type, options->replay,
+                                options->use_iv);
+}
+
+/*
+ * Initialize the persistent component of OpenVPN's TLS mode,
+ * which is preserved across SIGUSR1 resets.
+ */
+static void
+do_init_crypto_tls_c1(struct context *c)
+{
+    const struct options *options = &c->options;
+
+    if (!tls_ctx_initialised(&c->c1.ks.ssl_ctx))
+    {
+        /*
+         * Initialize the OpenSSL library's global
+         * SSL context.
+         */
+        init_ssl(options, &(c->c1.ks.ssl_ctx));
+        if (!tls_ctx_initialised(&c->c1.ks.ssl_ctx))
+        {
+#if P2MP
+            switch (auth_retry_get())
+            {
+                case AR_NONE:
+                    msg(M_FATAL, "Error: private key password verification failed");
+                    break;
+
+                case AR_INTERACT:
+                    ssl_purge_auth(false);
+
+                case AR_NOINTERACT:
+                    c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Password failure error */
+                    break;
+
+                default:
+                    ASSERT(0);
+            }
+            c->sig->signal_text = "private-key-password-failure";
+            return;
+#else  /* if P2MP */
+            msg(M_FATAL, "Error: private key password verification failed");
+#endif
+        }
+
+        /* Get cipher & hash algorithms */
+        init_key_type(&c->c1.ks.key_type, options->ciphername, options->authname,
+                      options->keysize, true, true);
+
+        /* Initialize PRNG with config-specified digest */
+        prng_init(options->prng_hash, options->prng_nonce_secret_len);
+
+        /* TLS handshake authentication (--tls-auth) */
+        if (options->tls_auth_file)
+        {
+            /* Initialize key_type for tls-auth with auth only */
+            CLEAR(c->c1.ks.tls_auth_key_type);
+            if (!streq(options->authname, "none"))
+            {
+                c->c1.ks.tls_auth_key_type.digest = md_kt_get(options->authname);
+                c->c1.ks.tls_auth_key_type.hmac_length =
+                    md_kt_size(c->c1.ks.tls_auth_key_type.digest);
+            }
+            else
+            {
+                msg(M_FATAL, "ERROR: tls-auth enabled, but no valid --auth "
+                    "algorithm specified ('%s')", options->authname);
+            }
+
+            crypto_read_openvpn_key(&c->c1.ks.tls_auth_key_type,
+                                    &c->c1.ks.tls_wrap_key, options->tls_auth_file,
+                                    options->tls_auth_file_inline, options->key_direction,
+                                    "Control Channel Authentication", "tls-auth");
+        }
+
+        /* TLS handshake encryption+authentication (--tls-crypt) */
+        if (options->tls_crypt_file)
+        {
+            tls_crypt_init_key(&c->c1.ks.tls_wrap_key, options->tls_crypt_file,
+                               options->tls_crypt_inline, options->tls_server);
+        }
+
+#if 0 /* was: #if ENABLE_INLINE_FILES --  Note that enabling this code will break restarts */
+        if (options->priv_key_file_inline)
+        {
+            string_clear(c->options.priv_key_file_inline);
+            c->options.priv_key_file_inline = NULL;
+        }
+#endif
+    }
+    else
+    {
+        msg(D_INIT_MEDIUM, "Re-using SSL/TLS context");
+    }
+}
+
+static void
+do_init_crypto_tls(struct context *c, const unsigned int flags)
+{
+    const struct options *options = &c->options;
+    struct tls_options to;
+    bool packet_id_long_form;
+
+    ASSERT(options->tls_server || options->tls_client);
+    ASSERT(!options->test_crypto);
+
+    init_crypto_pre(c, flags);
+
+    /* Make sure we are either a TLS client or server but not both */
+    ASSERT(options->tls_server == !options->tls_client);
+
+    /* initialize persistent component */
+    do_init_crypto_tls_c1(c);
+    if (IS_SIG(c))
+    {
+        return;
+    }
+
+    /* Sanity check on IV, sequence number, and cipher mode options */
+    check_replay_iv_consistency(&c->c1.ks.key_type, options->replay,
+                                options->use_iv);
+
+    /* In short form, unique datagram identifier is 32 bits, in long form 64 bits */
+    packet_id_long_form = cipher_kt_mode_ofb_cfb(c->c1.ks.key_type.cipher);
+
+    /* Compute MTU parameters (postpone if we push/pull options) */
+    if (c->options.pull || c->options.mode == MODE_SERVER)
+    {
+        /* Account for worst-case crypto overhead before allocating buffers */
+        frame_add_to_extra_frame(&c->c2.frame, crypto_max_overhead());
+    }
+    else
+    {
+        crypto_adjust_frame_parameters(&c->c2.frame, &c->c1.ks.key_type,
+                                       options->use_iv, options->replay, packet_id_long_form);
+    }
+    tls_adjust_frame_parameters(&c->c2.frame);
+
+    /* Set all command-line TLS-related options */
+    CLEAR(to);
+
+    if (options->use_iv)
+    {
+        to.crypto_flags |= CO_USE_IV;
+    }
+
+    if (options->mute_replay_warnings)
+    {
+        to.crypto_flags |= CO_MUTE_REPLAY_WARNINGS;
+    }
+
+    to.crypto_flags &= ~(CO_PACKET_ID_LONG_FORM);
+    if (packet_id_long_form)
+    {
+        to.crypto_flags |= CO_PACKET_ID_LONG_FORM;
+    }
+
+    to.ssl_ctx = c->c1.ks.ssl_ctx;
+    to.key_type = c->c1.ks.key_type;
+    to.server = options->tls_server;
+    to.key_method = options->key_method;
+    to.replay = options->replay;
+    to.replay_window = options->replay_window;
+    to.replay_time = options->replay_time;
+    to.tcp_mode = link_socket_proto_connection_oriented(options->ce.proto);
+    to.config_ciphername = c->c1.ciphername;
+    to.config_authname = c->c1.authname;
+    to.ncp_enabled = options->ncp_enabled;
+    to.transition_window = options->transition_window;
+    to.handshake_window = options->handshake_window;
+    to.packet_timeout = options->tls_timeout;
+    to.renegotiate_bytes = options->renegotiate_bytes;
+    to.renegotiate_packets = options->renegotiate_packets;
+    to.renegotiate_seconds = options->renegotiate_seconds;
+    to.single_session = options->single_session;
+    to.mode = options->mode;
+    to.pull = options->pull;
+#ifdef ENABLE_PUSH_PEER_INFO
+    if (options->push_peer_info)        /* all there is */
+    {
+        to.push_peer_info_detail = 2;
+    }
+    else if (options->pull)             /* pull clients send some details */
+    {
+        to.push_peer_info_detail = 1;
+    }
+    else                                /* default: no peer-info at all */
+    {
+        to.push_peer_info_detail = 0;
+    }
+#endif
+
+    /* should we not xmit any packets until we get an initial
+     * response from client? */
+    if (to.server && options->ce.proto == PROTO_TCP_SERVER)
+    {
+        to.xmit_hold = true;
+    }
+
+#ifdef ENABLE_OCC
+    to.disable_occ = !options->occ;
+#endif
+
+    to.verify_command = options->tls_verify;
+    to.verify_export_cert = options->tls_export_cert;
+    to.verify_x509_type = (options->verify_x509_type & 0xff);
+    to.verify_x509_name = options->verify_x509_name;
+    to.crl_file = options->crl_file;
+    to.crl_file_inline = options->crl_file_inline;
+    to.ssl_flags = options->ssl_flags;
+    to.ns_cert_type = options->ns_cert_type;
+    memmove(to.remote_cert_ku, options->remote_cert_ku, sizeof(to.remote_cert_ku));
+    to.remote_cert_eku = options->remote_cert_eku;
+    to.verify_hash = options->verify_hash;
+    to.verify_hash_algo = options->verify_hash_algo;
+#ifdef ENABLE_X509ALTUSERNAME
+    to.x509_username_field = (char *) options->x509_username_field;
+#else
+    to.x509_username_field = X509_USERNAME_FIELD_DEFAULT;
+#endif
+    to.es = c->c2.es;
+
+#ifdef ENABLE_DEBUG
+    to.gremlin = c->options.gremlin;
+#endif
+
+    to.plugins = c->plugins;
+
+#ifdef MANAGEMENT_DEF_AUTH
+    to.mda_context = &c->c2.mda_context;
+#endif
+
+#if P2MP_SERVER
+    to.auth_user_pass_verify_script = options->auth_user_pass_verify_script;
+    to.auth_user_pass_verify_script_via_file = options->auth_user_pass_verify_script_via_file;
+    to.tmp_dir = options->tmp_dir;
+    if (options->ccd_exclusive)
+    {
+        to.client_config_dir_exclusive = options->client_config_dir;
+    }
+    to.auth_user_pass_file = options->auth_user_pass_file;
+    to.auth_token_generate = options->auth_token_generate;
+    to.auth_token_lifetime = options->auth_token_lifetime;
+#endif
+
+    to.x509_track = options->x509_track;
+
+#if P2MP
+#ifdef ENABLE_CLIENT_CR
+    to.sci = &options->sc_info;
+#endif
+#endif
+
+#ifdef USE_COMP
+    to.comp_options = options->comp;
+#endif
+
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10001000
+    if (options->keying_material_exporter_label)
+    {
+        to.ekm_size = options->keying_material_exporter_length;
+        if (to.ekm_size < 16 || to.ekm_size > 4095)
+        {
+            to.ekm_size = 0;
+        }
+
+        to.ekm_label = options->keying_material_exporter_label;
+        to.ekm_label_size = strlen(to.ekm_label);
+    }
+    else
+    {
+        to.ekm_size = 0;
+    }
+#endif
+
+    /* TLS handshake authentication (--tls-auth) */
+    if (options->tls_auth_file)
+    {
+        to.tls_wrap.mode = TLS_WRAP_AUTH;
+        to.tls_wrap.opt.key_ctx_bi = c->c1.ks.tls_wrap_key;
+        to.tls_wrap.opt.pid_persist = &c->c1.pid_persist;
+        to.tls_wrap.opt.flags |= CO_PACKET_ID_LONG_FORM;
+        crypto_adjust_frame_parameters(&to.frame,
+                                       &c->c1.ks.tls_auth_key_type,
+                                       false, true, true);
+    }
+
+    /* TLS handshake encryption (--tls-crypt) */
+    if (options->tls_crypt_file)
+    {
+        to.tls_wrap.mode = TLS_WRAP_CRYPT;
+        to.tls_wrap.opt.key_ctx_bi = c->c1.ks.tls_wrap_key;
+        to.tls_wrap.opt.pid_persist = &c->c1.pid_persist;
+        to.tls_wrap.opt.flags |= CO_PACKET_ID_LONG_FORM;
+        tls_crypt_adjust_frame_parameters(&to.frame);
+    }
+
+    /* If we are running over TCP, allow for
+     * length prefix */
+    socket_adjust_frame_parameters(&to.frame, options->ce.proto);
+
+    /*
+     * Initialize OpenVPN's master TLS-mode object.
+     */
+    if (flags & CF_INIT_TLS_MULTI)
+    {
+        c->c2.tls_multi = tls_multi_init(&to);
+    }
+
+    if (flags & CF_INIT_TLS_AUTH_STANDALONE)
+    {
+        c->c2.tls_auth_standalone = tls_auth_standalone_init(&to, &c->c2.gc);
+    }
+}
+
+static void
+do_init_finalize_tls_frame(struct context *c)
+{
+    if (c->c2.tls_multi)
+    {
+        tls_multi_init_finalize(c->c2.tls_multi, &c->c2.frame);
+        ASSERT(EXPANDED_SIZE(&c->c2.tls_multi->opt.frame) <=
+               EXPANDED_SIZE(&c->c2.frame));
+        frame_print(&c->c2.tls_multi->opt.frame, D_MTU_INFO,
+                    "Control Channel MTU parms");
+    }
+    if (c->c2.tls_auth_standalone)
+    {
+        tls_auth_standalone_finalize(c->c2.tls_auth_standalone, &c->c2.frame);
+        frame_print(&c->c2.tls_auth_standalone->frame, D_MTU_INFO,
+                    "TLS-Auth MTU parms");
+    }
+}
+
+/*
+ * No encryption or authentication.
+ */
+static void
+do_init_crypto_none(const struct context *c)
+{
+    ASSERT(!c->options.test_crypto);
+    msg(M_WARN,
+        "******* WARNING *******: All encryption and authentication features "
+        "disabled -- All data will be tunnelled as clear text and will not be "
+        "protected against man-in-the-middle changes. "
+        "PLEASE DO RECONSIDER THIS CONFIGURATION!");
+}
+#endif /* ifdef ENABLE_CRYPTO */
+
+static void
+do_init_crypto(struct context *c, const unsigned int flags)
+{
+#ifdef ENABLE_CRYPTO
+    if (c->options.shared_secret_file)
+    {
+        do_init_crypto_static(c, flags);
+    }
+    else if (c->options.tls_server || c->options.tls_client)
+    {
+        do_init_crypto_tls(c, flags);
+    }
+    else                        /* no encryption or authentication. */
+    {
+        do_init_crypto_none(c);
+    }
+#else /* ENABLE_CRYPTO */
+    msg(M_WARN,
+        "******* WARNING *******: " PACKAGE_NAME
+        " built without crypto library -- encryption and authentication features disabled -- all data will be tunnelled as cleartext");
+#endif /* ENABLE_CRYPTO */
+}
+
+static void
+do_init_frame(struct context *c)
+{
+#ifdef USE_COMP
+    /*
+     * modify frame parameters if compression is enabled
+     */
+    if (comp_enabled(&c->options.comp))
+    {
+        comp_add_to_extra_frame(&c->c2.frame);
+
+#if !defined(ENABLE_LZ4)
+        /*
+         * Compression usage affects buffer alignment when non-swapped algs
+         * such as LZO is used.
+         * Newer algs like LZ4 and comp-stub with COMP_F_SWAP don't need
+         * any special alignment because of the control-byte swap approach.
+         * LZO alignment (on the other hand) is problematic because
+         * the presence of the control byte means that either the output of
+         * decryption must be written to an unaligned buffer, or the input
+         * to compression (or packet dispatch if packet is uncompressed)
+         * must be read from an unaligned buffer.
+         * This code tries to align the input to compression (or packet
+         * dispatch if packet is uncompressed) at the cost of requiring
+         * decryption output to be written to an unaligned buffer, so
+         * it's more of a tradeoff than an optimal solution and we don't
+         * include it when we are doing a modern build with LZ4.
+         * Strictly speaking, on the server it would be better to execute
+         * this code for every connection after we decide the compression
+         * method, but currently the frame code doesn't appear to be
+         * flexible enough for this, since the frame is already established
+         * before it is known which compression options will be pushed.
+         */
+        if (comp_unswapped_prefix(&c->options.comp) && CIPHER_ENABLED(c))
+        {
+            frame_add_to_align_adjust(&c->c2.frame, COMP_PREFIX_LEN);
+            frame_or_align_flags(&c->c2.frame,
+                                 FRAME_HEADROOM_MARKER_FRAGMENT
+                                 |FRAME_HEADROOM_MARKER_DECRYPT);
+        }
+#endif
+
+#ifdef ENABLE_FRAGMENT
+        comp_add_to_extra_frame(&c->c2.frame_fragment_omit); /* omit compression frame delta from final frame_fragment */
+#endif
+    }
+#endif /* USE_COMP */
+
+    /*
+     * Adjust frame size for UDP Socks support.
+     */
+    if (c->options.ce.socks_proxy_server)
+    {
+        socks_adjust_frame_parameters(&c->c2.frame, c->options.ce.proto);
+    }
+
+    /*
+     * Adjust frame size based on the --tun-mtu-extra parameter.
+     */
+    if (c->options.ce.tun_mtu_extra_defined)
+    {
+        tun_adjust_frame_parameters(&c->c2.frame, c->options.ce.tun_mtu_extra);
+    }
+
+    /*
+     * Adjust frame size based on link socket parameters.
+     * (Since TCP is a stream protocol, we need to insert
+     * a packet length uint16_t in the buffer.)
+     */
+    socket_adjust_frame_parameters(&c->c2.frame, c->options.ce.proto);
+
+    /*
+     * Fill in the blanks in the frame parameters structure,
+     * make sure values are rational, etc.
+     */
+    frame_finalize_options(c, NULL);
+
+#ifdef USE_COMP
+    /*
+     * Modify frame parameters if compression is compiled in.
+     * Should be called after frame_finalize_options.
+     */
+    comp_add_to_extra_buffer(&c->c2.frame);
+#ifdef ENABLE_FRAGMENT
+    comp_add_to_extra_buffer(&c->c2.frame_fragment_omit); /* omit compression frame delta from final frame_fragment */
+#endif
+#endif /* USE_COMP */
+
+    /* packets with peer-id (P_DATA_V2) need 3 extra bytes in frame (on client)
+     * and need link_mtu+3 bytes on socket reception (on server).
+     *
+     * accomodate receive path in f->extra_link, which has the side effect of
+     * also increasing send buffers (BUF_SIZE() macro), which need to be
+     * allocated big enough before receiving peer-id option from server.
+     *
+     * f->extra_frame is adjusted when peer-id option is push-received
+     */
+    frame_add_to_extra_link(&c->c2.frame, 3);
+
+#ifdef ENABLE_FRAGMENT
+    /*
+     * Set frame parameter for fragment code.  This is necessary because
+     * the fragmentation code deals with payloads which have already been
+     * passed through the compression code.
+     */
+    c->c2.frame_fragment = c->c2.frame;
+    frame_subtract_extra(&c->c2.frame_fragment, &c->c2.frame_fragment_omit);
+    c->c2.frame_fragment_initial = c->c2.frame_fragment;
+#endif
+
+#if defined(ENABLE_FRAGMENT) && defined(ENABLE_OCC)
+    /*
+     * MTU advisories
+     */
+    if (c->options.ce.fragment && c->options.mtu_test)
+    {
+        msg(M_WARN,
+            "WARNING: using --fragment and --mtu-test together may produce an inaccurate MTU test result");
+    }
+#endif
+
+#ifdef ENABLE_FRAGMENT
+    if ((c->options.ce.mssfix || c->options.ce.fragment)
+        && TUN_MTU_SIZE(&c->c2.frame_fragment) != ETHERNET_MTU)
+    {
+        msg(M_WARN,
+            "WARNING: normally if you use --mssfix and/or --fragment, you should also set --tun-mtu %d (currently it is %d)",
+            ETHERNET_MTU, TUN_MTU_SIZE(&c->c2.frame_fragment));
+    }
+#endif
+}
+
+static void
+do_option_warnings(struct context *c)
+{
+    const struct options *o = &c->options;
+
+    if (o->ping_send_timeout && !o->ping_rec_timeout)
+    {
+        msg(M_WARN, "WARNING: --ping should normally be used with --ping-restart or --ping-exit");
+    }
+
+    if (o->username || o->groupname || o->chroot_dir
+#ifdef ENABLE_SELINUX
+        || o->selinux_context
+#endif
+        )
+    {
+        if (!o->persist_tun)
+        {
+            msg(M_WARN, "WARNING: you are using user/group/chroot/setcon without persist-tun -- this may cause restarts to fail");
+        }
+        if (!o->persist_key
+#ifdef ENABLE_PKCS11
+            && !o->pkcs11_id
+#endif
+            )
+        {
+            msg(M_WARN, "WARNING: you are using user/group/chroot/setcon without persist-key -- this may cause restarts to fail");
+        }
+    }
+
+    if (o->chroot_dir && !(o->username && o->groupname))
+    {
+        msg(M_WARN, "WARNING: you are using chroot without specifying user and group -- this may cause the chroot jail to be insecure");
+    }
+
+#if P2MP
+    if (o->pull && o->ifconfig_local && c->first_time)
+    {
+        msg(M_WARN, "WARNING: using --pull/--client and --ifconfig together is probably not what you want");
+    }
+
+#if P2MP_SERVER
+    if (o->server_bridge_defined | o->server_bridge_proxy_dhcp)
+    {
+        msg(M_WARN, "NOTE: when bridging your LAN adapter with the TAP adapter, note that the new bridge adapter will often take on its own IP address that is different from what the LAN adapter was previously set to");
+    }
+
+    if (o->mode == MODE_SERVER)
+    {
+        if (o->duplicate_cn && o->client_config_dir)
+        {
+            msg(M_WARN, "WARNING: using --duplicate-cn and --client-config-dir together is probably not what you want");
+        }
+        if (o->duplicate_cn && o->ifconfig_pool_persist_filename)
+        {
+            msg(M_WARN, "WARNING: --ifconfig-pool-persist will not work with --duplicate-cn");
+        }
+        if (!o->keepalive_ping || !o->keepalive_timeout)
+        {
+            msg(M_WARN, "WARNING: --keepalive option is missing from server config");
+        }
+    }
+#endif /* if P2MP_SERVER */
+#endif /* if P2MP */
+
+#ifdef ENABLE_CRYPTO
+    if (!o->replay)
+    {
+        msg(M_WARN, "WARNING: You have disabled Replay Protection (--no-replay) which may make " PACKAGE_NAME " less secure");
+    }
+    if (!o->use_iv)
+    {
+        msg(M_WARN, "WARNING: You have disabled Crypto IVs (--no-iv) which may make " PACKAGE_NAME " less secure");
+    }
+
+    if (o->tls_server)
+    {
+        warn_on_use_of_common_subnets();
+    }
+    if (o->tls_client
+        && !o->tls_verify
+        && o->verify_x509_type == VERIFY_X509_NONE
+        && !(o->ns_cert_type & NS_CERT_CHECK_SERVER)
+        && !o->remote_cert_eku)
+    {
+        msg(M_WARN, "WARNING: No server certificate verification method has been enabled.  See http://openvpn.net/howto.html#mitm for more info.");
+    }
+    if (o->ns_cert_type)
+    {
+        msg(M_WARN, "WARNING: --ns-cert-type is DEPRECATED.  Use --remote-cert-tls instead.");
+    }
+#endif /* ifdef ENABLE_CRYPTO */
+
+    /* If a script is used, print appropiate warnings */
+    if (o->user_script_used)
+    {
+        if (script_security >= SSEC_SCRIPTS)
+        {
+            msg(M_WARN, "NOTE: the current --script-security setting may allow this configuration to call user-defined scripts");
+        }
+        else if (script_security >= SSEC_PW_ENV)
+        {
+            msg(M_WARN, "WARNING: the current --script-security setting may allow passwords to be passed to scripts via environmental variables");
+        }
+        else
+        {
+            msg(M_WARN, "NOTE: starting with " PACKAGE_NAME " 2.1, '--script-security 2' or higher is required to call user-defined scripts or executables");
+        }
+    }
+}
+
+static void
+do_init_frame_tls(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    do_init_finalize_tls_frame(c);
+#endif
+}
+
+struct context_buffers *
+init_context_buffers(const struct frame *frame)
+{
+    struct context_buffers *b;
+
+    ALLOC_OBJ_CLEAR(b, struct context_buffers);
+
+    b->read_link_buf = alloc_buf(BUF_SIZE(frame));
+    b->read_tun_buf = alloc_buf(BUF_SIZE(frame));
+
+    b->aux_buf = alloc_buf(BUF_SIZE(frame));
+
+#ifdef ENABLE_CRYPTO
+    b->encrypt_buf = alloc_buf(BUF_SIZE(frame));
+    b->decrypt_buf = alloc_buf(BUF_SIZE(frame));
+#endif
+
+#ifdef USE_COMP
+    b->compress_buf = alloc_buf(BUF_SIZE(frame));
+    b->decompress_buf = alloc_buf(BUF_SIZE(frame));
+#endif
+
+    return b;
+}
+
+void
+free_context_buffers(struct context_buffers *b)
+{
+    if (b)
+    {
+        free_buf(&b->read_link_buf);
+        free_buf(&b->read_tun_buf);
+        free_buf(&b->aux_buf);
+
+#ifdef USE_COMP
+        free_buf(&b->compress_buf);
+        free_buf(&b->decompress_buf);
+#endif
+
+#ifdef ENABLE_CRYPTO
+        free_buf(&b->encrypt_buf);
+        free_buf(&b->decrypt_buf);
+#endif
+
+        free(b);
+    }
+}
+
+/*
+ * Now that we know all frame parameters, initialize
+ * our buffers.
+ */
+static void
+do_init_buffers(struct context *c)
+{
+    c->c2.buffers = init_context_buffers(&c->c2.frame);
+    c->c2.buffers_owned = true;
+}
+
+#ifdef ENABLE_FRAGMENT
+/*
+ * Fragmenting code has buffers to initialize
+ * once frame parameters are known.
+ */
+static void
+do_init_fragment(struct context *c)
+{
+    ASSERT(c->options.ce.fragment);
+    frame_set_mtu_dynamic(&c->c2.frame_fragment,
+                          c->options.ce.fragment, SET_MTU_UPPER_BOUND);
+    fragment_frame_init(c->c2.fragment, &c->c2.frame_fragment);
+}
+#endif
+
+/*
+ * Allocate our socket object.
+ */
+static void
+do_link_socket_new(struct context *c)
+{
+    ASSERT(!c->c2.link_socket);
+    c->c2.link_socket = link_socket_new();
+    c->c2.link_socket_owned = true;
+}
+
+/*
+ * bind the TCP/UDP socket
+ */
+static void
+do_init_socket_1(struct context *c, const int mode)
+{
+    unsigned int sockflags = c->options.sockflags;
+
+#if PORT_SHARE
+    if (c->options.port_share_host && c->options.port_share_port)
+    {
+        sockflags |= SF_PORT_SHARE;
+    }
+#endif
+
+    link_socket_init_phase1(c->c2.link_socket,
+                            c->options.ce.local,
+                            c->options.ce.local_port,
+                            c->options.ce.remote,
+                            c->options.ce.remote_port,
+                            c->c1.dns_cache,
+                            c->options.ce.proto,
+                            c->options.ce.af,
+                            c->options.ce.bind_ipv6_only,
+                            mode,
+                            c->c2.accept_from,
+                            c->c1.http_proxy,
+                            c->c1.socks_proxy,
+#ifdef ENABLE_DEBUG
+                            c->options.gremlin,
+#endif
+                            c->options.ce.bind_local,
+                            c->options.ce.remote_float,
+                            c->options.inetd,
+                            &c->c1.link_socket_addr,
+                            c->options.ipchange,
+                            c->plugins,
+                            c->options.resolve_retry_seconds,
+                            c->options.ce.mtu_discover_type,
+                            c->options.rcvbuf,
+                            c->options.sndbuf,
+                            c->options.mark,
+                            &c->c2.server_poll_interval,
+                            sockflags);
+}
+
+/*
+ * finalize the TCP/UDP socket
+ */
+static void
+do_init_socket_2(struct context *c)
+{
+    link_socket_init_phase2(c->c2.link_socket, &c->c2.frame,
+                            c->sig);
+}
+
+/*
+ * Print MTU INFO
+ */
+static void
+do_print_data_channel_mtu_parms(struct context *c)
+{
+    frame_print(&c->c2.frame, D_MTU_INFO, "Data Channel MTU parms");
+#ifdef ENABLE_FRAGMENT
+    if (c->c2.fragment)
+    {
+        frame_print(&c->c2.frame_fragment, D_MTU_INFO,
+                    "Fragmentation MTU parms");
+    }
+#endif
+}
+
+#ifdef ENABLE_OCC
+/*
+ * Get local and remote options compatibility strings.
+ */
+static void
+do_compute_occ_strings(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+
+    c->c2.options_string_local =
+        options_string(&c->options, &c->c2.frame, c->c1.tuntap, false, &gc);
+    c->c2.options_string_remote =
+        options_string(&c->options, &c->c2.frame, c->c1.tuntap, true, &gc);
+
+    msg(D_SHOW_OCC, "Local Options String (VER=%s): '%s'",
+        options_string_version(c->c2.options_string_local, &gc),
+        c->c2.options_string_local);
+    msg(D_SHOW_OCC, "Expected Remote Options String (VER=%s): '%s'",
+        options_string_version(c->c2.options_string_remote, &gc),
+        c->c2.options_string_remote);
+
+#ifdef ENABLE_CRYPTO
+    if (c->c2.tls_multi)
+    {
+        tls_multi_init_set_options(c->c2.tls_multi,
+                                   c->c2.options_string_local,
+                                   c->c2.options_string_remote);
+    }
+#endif
+
+    gc_free(&gc);
+}
+#endif /* ifdef ENABLE_OCC */
+
+/*
+ * These things can only be executed once per program instantiation.
+ * Set up for possible UID/GID downgrade, but don't do it yet.
+ * Daemonize if requested.
+ */
+static void
+do_init_first_time(struct context *c)
+{
+    if (c->first_time && !c->c0)
+    {
+        struct context_0 *c0;
+
+        ALLOC_OBJ_CLEAR_GC(c->c0, struct context_0, &c->gc);
+        c0 = c->c0;
+
+        /* get user and/or group that we want to setuid/setgid to */
+        c0->uid_gid_specified =
+            platform_group_get(c->options.groupname, &c0->platform_state_group)
+            |platform_user_get(c->options.username, &c0->platform_state_user);
+
+        /* perform postponed chdir if --daemon */
+        if (c->did_we_daemonize && c->options.cd_dir == NULL)
+        {
+            platform_chdir("/");
+        }
+
+        /* should we change scheduling priority? */
+        platform_nice(c->options.nice);
+    }
+}
+
+/*
+ * If xinetd/inetd mode, don't allow restart.
+ */
+static void
+do_close_check_if_restart_permitted(struct context *c)
+{
+    if (c->options.inetd
+        && (c->sig->signal_received == SIGHUP
+            || c->sig->signal_received == SIGUSR1))
+    {
+        c->sig->signal_received = SIGTERM;
+        msg(M_INFO,
+            PACKAGE_NAME
+            " started by inetd/xinetd cannot restart... Exiting.");
+    }
+}
+
+/*
+ * free buffers
+ */
+static void
+do_close_free_buf(struct context *c)
+{
+    if (c->c2.buffers_owned)
+    {
+        free_context_buffers(c->c2.buffers);
+        c->c2.buffers = NULL;
+        c->c2.buffers_owned = false;
+    }
+}
+
+/*
+ * close TLS
+ */
+static void
+do_close_tls(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    if (c->c2.tls_multi)
+    {
+        tls_multi_free(c->c2.tls_multi, true);
+        c->c2.tls_multi = NULL;
+    }
+
+#ifdef ENABLE_OCC
+    /* free options compatibility strings */
+    if (c->c2.options_string_local)
+    {
+        free(c->c2.options_string_local);
+    }
+    if (c->c2.options_string_remote)
+    {
+        free(c->c2.options_string_remote);
+    }
+    c->c2.options_string_local = c->c2.options_string_remote = NULL;
+#endif
+
+    if (c->c2.pulled_options_state)
+    {
+        md_ctx_cleanup(c->c2.pulled_options_state);
+        md_ctx_free(c->c2.pulled_options_state);
+    }
+#endif
+}
+
+/*
+ * Free key schedules
+ */
+static void
+do_close_free_key_schedule(struct context *c, bool free_ssl_ctx)
+{
+    if (!(c->sig->signal_received == SIGUSR1 && c->options.persist_key))
+    {
+        key_schedule_free(&c->c1.ks, free_ssl_ctx);
+    }
+}
+
+/*
+ * Close TCP/UDP connection
+ */
+static void
+do_close_link_socket(struct context *c)
+{
+    if (c->c2.link_socket && c->c2.link_socket_owned)
+    {
+        link_socket_close(c->c2.link_socket);
+        c->c2.link_socket = NULL;
+    }
+
+
+    /* Preserve the resolved list of remote if the user request to or if we want
+     * reconnect to the same host again or there are still addresses that need
+     * to be tried */
+    if (!(c->sig->signal_received == SIGUSR1
+          && ( (c->options.persist_remote_ip)
+               ||
+               ( c->sig->source != SIG_SOURCE_HARD
+                 && ((c->c1.link_socket_addr.current_remote && c->c1.link_socket_addr.current_remote->ai_next)
+                     || c->options.no_advance))
+               )))
+    {
+        clear_remote_addrlist(&c->c1.link_socket_addr, !c->options.resolve_in_advance);
+    }
+
+    /* Clear the remote actual address when persist_remote_ip is not in use */
+    if (!(c->sig->signal_received == SIGUSR1 && c->options.persist_remote_ip))
+    {
+        CLEAR(c->c1.link_socket_addr.actual);
+    }
+
+    if (!(c->sig->signal_received == SIGUSR1 && c->options.persist_local_ip))
+    {
+        if (c->c1.link_socket_addr.bind_local && !c->options.resolve_in_advance)
+        {
+            freeaddrinfo(c->c1.link_socket_addr.bind_local);
+        }
+
+        c->c1.link_socket_addr.bind_local = NULL;
+    }
+}
+
+/*
+ * Close packet-id persistance file
+ */
+static void
+do_close_packet_id(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    packet_id_free(&c->c2.crypto_options.packet_id);
+    packet_id_persist_save(&c->c1.pid_persist);
+    if (!(c->sig->signal_received == SIGUSR1))
+    {
+        packet_id_persist_close(&c->c1.pid_persist);
+    }
+#endif
+}
+
+#ifdef ENABLE_FRAGMENT
+/*
+ * Close fragmentation handler.
+ */
+static void
+do_close_fragment(struct context *c)
+{
+    if (c->c2.fragment)
+    {
+        fragment_free(c->c2.fragment);
+        c->c2.fragment = NULL;
+    }
+}
+#endif
+
+/*
+ * Open and close our event objects.
+ */
+
+static void
+do_event_set_init(struct context *c,
+                  bool need_us_timeout)
+{
+    unsigned int flags = 0;
+
+    c->c2.event_set_max = BASE_N_EVENTS;
+
+    flags |= EVENT_METHOD_FAST;
+
+    if (need_us_timeout)
+    {
+        flags |= EVENT_METHOD_US_TIMEOUT;
+    }
+
+    c->c2.event_set = event_set_init(&c->c2.event_set_max, flags);
+    c->c2.event_set_owned = true;
+}
+
+static void
+do_close_event_set(struct context *c)
+{
+    if (c->c2.event_set && c->c2.event_set_owned)
+    {
+        event_free(c->c2.event_set);
+        c->c2.event_set = NULL;
+        c->c2.event_set_owned = false;
+    }
+}
+
+/*
+ * Open and close --status file
+ */
+
+static void
+do_open_status_output(struct context *c)
+{
+    if (!c->c1.status_output)
+    {
+        c->c1.status_output = status_open(c->options.status_file,
+                                          c->options.status_file_update_freq,
+                                          -1,
+                                          NULL,
+                                          STATUS_OUTPUT_WRITE);
+        c->c1.status_output_owned = true;
+    }
+}
+
+static void
+do_close_status_output(struct context *c)
+{
+    if (!(c->sig->signal_received == SIGUSR1))
+    {
+        if (c->c1.status_output_owned && c->c1.status_output)
+        {
+            status_close(c->c1.status_output);
+            c->c1.status_output = NULL;
+            c->c1.status_output_owned = false;
+        }
+    }
+}
+
+/*
+ * Handle ifconfig-pool persistance object.
+ */
+static void
+do_open_ifconfig_pool_persist(struct context *c)
+{
+#if P2MP_SERVER
+    if (!c->c1.ifconfig_pool_persist && c->options.ifconfig_pool_persist_filename)
+    {
+        c->c1.ifconfig_pool_persist = ifconfig_pool_persist_init(c->options.ifconfig_pool_persist_filename,
+                                                                 c->options.ifconfig_pool_persist_refresh_freq);
+        c->c1.ifconfig_pool_persist_owned = true;
+    }
+#endif
+}
+
+static void
+do_close_ifconfig_pool_persist(struct context *c)
+{
+#if P2MP_SERVER
+    if (!(c->sig->signal_received == SIGUSR1))
+    {
+        if (c->c1.ifconfig_pool_persist && c->c1.ifconfig_pool_persist_owned)
+        {
+            ifconfig_pool_persist_close(c->c1.ifconfig_pool_persist);
+            c->c1.ifconfig_pool_persist = NULL;
+            c->c1.ifconfig_pool_persist_owned = false;
+        }
+    }
+#endif
+}
+
+/*
+ * Inherit environmental variables
+ */
+
+static void
+do_inherit_env(struct context *c, const struct env_set *src)
+{
+    c->c2.es = env_set_create(NULL);
+    c->c2.es_owned = true;
+    env_set_inherit(c->c2.es, src);
+}
+
+static void
+do_env_set_destroy(struct context *c)
+{
+    if (c->c2.es && c->c2.es_owned)
+    {
+        env_set_destroy(c->c2.es);
+        c->c2.es = NULL;
+        c->c2.es_owned = false;
+    }
+}
+
+/*
+ * Fast I/O setup.  Fast I/O is an optimization which only works
+ * if all of the following are true:
+ *
+ * (1) The platform is not Windows
+ * (2) --proto udp is enabled
+ * (3) --shaper is disabled
+ */
+static void
+do_setup_fast_io(struct context *c)
+{
+    if (c->options.fast_io)
+    {
+#ifdef _WIN32
+        msg(M_INFO, "NOTE: --fast-io is disabled since we are running on Windows");
+#else
+        if (!proto_is_udp(c->options.ce.proto))
+        {
+            msg(M_INFO, "NOTE: --fast-io is disabled since we are not using UDP");
+        }
+        else
+        {
+#ifdef ENABLE_FEATURE_SHAPER
+            if (c->options.shaper)
+            {
+                msg(M_INFO, "NOTE: --fast-io is disabled since we are using --shaper");
+            }
+            else
+#endif
+            {
+                c->c2.fast_io = true;
+            }
+        }
+#endif
+    }
+}
+
+static void
+do_signal_on_tls_errors(struct context *c)
+{
+#ifdef ENABLE_CRYPTO
+    if (c->options.tls_exit)
+    {
+        c->c2.tls_exit_signal = SIGTERM;
+    }
+    else
+    {
+        c->c2.tls_exit_signal = SIGUSR1;
+    }
+#endif
+}
+
+#ifdef ENABLE_PLUGIN
+
+void
+init_plugins(struct context *c)
+{
+    if (c->options.plugin_list && !c->plugins)
+    {
+        c->plugins = plugin_list_init(c->options.plugin_list);
+        c->plugins_owned = true;
+    }
+}
+
+void
+open_plugins(struct context *c, const bool import_options, int init_point)
+{
+    if (c->plugins && c->plugins_owned)
+    {
+        if (import_options)
+        {
+            struct plugin_return pr, config;
+            plugin_return_init(&pr);
+            plugin_list_open(c->plugins, c->options.plugin_list, &pr, c->c2.es, init_point);
+            plugin_return_get_column(&pr, &config, "config");
+            if (plugin_return_defined(&config))
+            {
+                int i;
+                for (i = 0; i < config.n; ++i)
+                {
+                    unsigned int option_types_found = 0;
+                    if (config.list[i] && config.list[i]->value)
+                    {
+                        options_string_import(&c->options,
+                                              config.list[i]->value,
+                                              D_IMPORT_ERRORS|M_OPTERR,
+                                              OPT_P_DEFAULT & ~OPT_P_PLUGIN,
+                                              &option_types_found,
+                                              c->es);
+                    }
+                }
+            }
+            plugin_return_free(&pr);
+        }
+        else
+        {
+            plugin_list_open(c->plugins, c->options.plugin_list, NULL, c->c2.es, init_point);
+        }
+    }
+}
+
+static void
+do_close_plugins(struct context *c)
+{
+    if (c->plugins && c->plugins_owned && !(c->sig->signal_received == SIGUSR1))
+    {
+        plugin_list_close(c->plugins);
+        c->plugins = NULL;
+        c->plugins_owned = false;
+    }
+}
+
+static void
+do_inherit_plugins(struct context *c, const struct context *src)
+{
+    if (!c->plugins && src->plugins)
+    {
+        c->plugins = plugin_list_inherit(src->plugins);
+        c->plugins_owned = true;
+    }
+}
+
+#endif /* ifdef ENABLE_PLUGIN */
+
+#ifdef ENABLE_MANAGEMENT
+
+static void
+management_callback_status_p2p(void *arg, const int version, struct status_output *so)
+{
+    struct context *c = (struct context *) arg;
+    print_status(c, so);
+}
+
+void
+management_show_net_callback(void *arg, const int msglevel)
+{
+#ifdef _WIN32
+    show_routes(msglevel);
+    show_adapters(msglevel);
+    msg(msglevel, "END");
+#else
+    msg(msglevel, "ERROR: Sorry, this command is currently only implemented on Windows");
+#endif
+}
+
+#ifdef TARGET_ANDROID
+int
+management_callback_network_change(void *arg, bool samenetwork)
+{
+    /* Check if the client should translate the network change to a SIGUSR1 to
+     * reestablish the connection or just reprotect the socket
+     *
+     * At the moment just assume that, for all settings that use pull (not
+     * --static) and are not using peer-id reestablishing the connection is
+     * required (unless the network is the same)
+     *
+     * The function returns -1 on invalid fd and -2 if the socket cannot be
+     * reused. On the -2 return value the man_network_change function triggers
+     * a SIGUSR1 to force a reconnect.
+     */
+
+    int socketfd = -1;
+    struct context *c = (struct context *) arg;
+    if (!c->c2.link_socket)
+    {
+        return -1;
+    }
+    if (c->c2.link_socket->sd == SOCKET_UNDEFINED)
+    {
+        return -1;
+    }
+
+    socketfd = c->c2.link_socket->sd;
+    if (!c->options.pull || c->c2.tls_multi->use_peer_id || samenetwork)
+    {
+        return socketfd;
+    }
+    else
+    {
+        return -2;
+    }
+}
+#endif /* ifdef TARGET_ANDROID */
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+void
+init_management_callback_p2p(struct context *c)
+{
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        struct management_callback cb;
+        CLEAR(cb);
+        cb.arg = c;
+        cb.status = management_callback_status_p2p;
+        cb.show_net = management_show_net_callback;
+        cb.proxy_cmd = management_callback_proxy_cmd;
+        cb.remote_cmd = management_callback_remote_cmd;
+#ifdef TARGET_ANDROID
+        cb.network_change = management_callback_network_change;
+#endif
+        management_set_callback(management, &cb);
+    }
+#endif
+}
+
+#ifdef ENABLE_MANAGEMENT
+
+void
+init_management(void)
+{
+    if (!management)
+    {
+        management = management_init();
+    }
+}
+
+bool
+open_management(struct context *c)
+{
+    /* initialize management layer */
+    if (management)
+    {
+        if (c->options.management_addr)
+        {
+            unsigned int flags = c->options.management_flags;
+            if (c->options.mode == MODE_SERVER)
+            {
+                flags |= MF_SERVER;
+            }
+            if (management_open(management,
+                                c->options.management_addr,
+                                c->options.management_port,
+                                c->options.management_user_pass,
+                                c->options.management_client_user,
+                                c->options.management_client_group,
+                                c->options.management_log_history_cache,
+                                c->options.management_echo_buffer_size,
+                                c->options.management_state_buffer_size,
+                                c->options.management_write_peer_info_file,
+                                c->options.remap_sigusr1,
+                                flags))
+            {
+                management_set_state(management,
+                                     OPENVPN_STATE_CONNECTING,
+                                     NULL,
+                                     NULL,
+                                     NULL,
+                                     NULL,
+                                     NULL);
+            }
+
+            /* initial management hold, called early, before first context initialization */
+            do_hold(0);
+            if (IS_SIG(c))
+            {
+                msg(M_WARN, "Signal received from management interface, exiting");
+                return false;
+            }
+        }
+        else
+        {
+            close_management();
+        }
+    }
+    return true;
+}
+
+void
+close_management(void)
+{
+    if (management)
+    {
+        management_close(management);
+        management = NULL;
+    }
+}
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+
+void
+uninit_management_callback(void)
+{
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        management_clear_callback(management);
+    }
+#endif
+}
+
+/*
+ * Initialize a tunnel instance, handle pre and post-init
+ * signal settings.
+ */
+void
+init_instance_handle_signals(struct context *c, const struct env_set *env, const unsigned int flags)
+{
+    pre_init_signal_catch();
+    init_instance(c, env, flags);
+    post_init_signal_catch();
+
+    /*
+     * This is done so that signals thrown during
+     * initialization can bring us back to
+     * a management hold.
+     */
+    if (IS_SIG(c))
+    {
+        remap_signal(c);
+        uninit_management_callback();
+    }
+}
+
+/*
+ * Initialize a tunnel instance.
+ */
+void
+init_instance(struct context *c, const struct env_set *env, const unsigned int flags)
+{
+    const struct options *options = &c->options;
+    const bool child = (c->mode == CM_CHILD_TCP || c->mode == CM_CHILD_UDP);
+    int link_socket_mode = LS_MODE_DEFAULT;
+
+    /* init garbage collection level */
+    gc_init(&c->c2.gc);
+
+    /* inherit environmental variables */
+    if (env)
+    {
+        do_inherit_env(c, env);
+    }
+
+    /* signals caught here will abort */
+    c->sig->signal_received = 0;
+    c->sig->signal_text = NULL;
+    c->sig->source = SIG_SOURCE_SOFT;
+
+    if (c->mode == CM_P2P)
+    {
+        init_management_callback_p2p(c);
+    }
+
+    /* possible sleep or management hold if restart */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        do_startup_pause(c);
+        if (IS_SIG(c))
+        {
+            goto sig;
+        }
+    }
+
+    if (c->options.resolve_in_advance)
+    {
+        do_preresolve(c);
+        if (IS_SIG(c))
+        {
+            goto sig;
+        }
+    }
+
+    /* map in current connection entry */
+    next_connection_entry(c);
+
+    /* link_socket_mode allows CM_CHILD_TCP
+     * instances to inherit acceptable fds
+     * from a top-level parent */
+    if (c->options.ce.proto == PROTO_TCP_SERVER)
+    {
+        if (c->mode == CM_TOP)
+        {
+            link_socket_mode = LS_MODE_TCP_LISTEN;
+        }
+        else if (c->mode == CM_CHILD_TCP)
+        {
+            link_socket_mode = LS_MODE_TCP_ACCEPT_FROM;
+        }
+    }
+
+    /* should we disable paging? */
+    if (c->first_time && options->mlock)
+    {
+        platform_mlockall(true);
+    }
+
+#if P2MP
+    /* get passwords if undefined */
+    if (auth_retry_get() == AR_INTERACT)
+    {
+        init_query_passwords(c);
+    }
+#endif
+
+    /* initialize context level 2 --verb/--mute parms */
+    init_verb_mute(c, IVM_LEVEL_2);
+
+    /* set error message delay for non-server modes */
+    if (c->mode == CM_P2P)
+    {
+        set_check_status_error_delay(P2P_ERROR_DELAY_MS);
+    }
+
+    /* warn about inconsistent options */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        do_option_warnings(c);
+    }
+
+#ifdef ENABLE_PLUGIN
+    /* initialize plugins */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        open_plugins(c, false, OPENVPN_PLUGIN_INIT_PRE_DAEMON);
+    }
+#endif
+
+    /* should we enable fast I/O? */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        do_setup_fast_io(c);
+    }
+
+    /* should we throw a signal on TLS errors? */
+    do_signal_on_tls_errors(c);
+
+    /* open --status file */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        do_open_status_output(c);
+    }
+
+    /* open --ifconfig-pool-persist file */
+    if (c->mode == CM_TOP)
+    {
+        do_open_ifconfig_pool_persist(c);
+    }
+
+#ifdef ENABLE_OCC
+    /* reset OCC state */
+    if (c->mode == CM_P2P || child)
+    {
+        c->c2.occ_op = occ_reset_op();
+    }
+#endif
+
+    /* our wait-for-i/o objects, different for posix vs. win32 */
+    if (c->mode == CM_P2P)
+    {
+        do_event_set_init(c, SHAPER_DEFINED(&c->options));
+    }
+    else if (c->mode == CM_CHILD_TCP)
+    {
+        do_event_set_init(c, false);
+    }
+
+    /* initialize HTTP or SOCKS proxy object at scope level 2 */
+    init_proxy(c);
+
+    /* allocate our socket object */
+    if (c->mode == CM_P2P || c->mode == CM_TOP || c->mode == CM_CHILD_TCP)
+    {
+        do_link_socket_new(c);
+    }
+
+#ifdef ENABLE_FRAGMENT
+    /* initialize internal fragmentation object */
+    if (options->ce.fragment && (c->mode == CM_P2P || child))
+    {
+        c->c2.fragment = fragment_init(&c->c2.frame);
+    }
+#endif
+
+    /* init crypto layer */
+    {
+        unsigned int crypto_flags = 0;
+        if (c->mode == CM_TOP)
+        {
+            crypto_flags = CF_INIT_TLS_AUTH_STANDALONE;
+        }
+        else if (c->mode == CM_P2P)
+        {
+            crypto_flags = CF_LOAD_PERSISTED_PACKET_ID | CF_INIT_TLS_MULTI;
+        }
+        else if (child)
+        {
+            crypto_flags = CF_INIT_TLS_MULTI;
+        }
+        do_init_crypto(c, crypto_flags);
+        if (IS_SIG(c) && !child)
+        {
+            goto sig;
+        }
+    }
+
+#ifdef USE_COMP
+    /* initialize compression library. */
+    if (comp_enabled(&options->comp) && (c->mode == CM_P2P || child))
+    {
+        c->c2.comp_context = comp_init(&options->comp);
+    }
+#endif
+
+    /* initialize MTU variables */
+    do_init_frame(c);
+
+    /* initialize TLS MTU variables */
+    do_init_frame_tls(c);
+
+    /* init workspace buffers whose size is derived from frame size */
+    if (c->mode == CM_P2P || c->mode == CM_CHILD_TCP)
+    {
+        do_init_buffers(c);
+    }
+
+#ifdef ENABLE_FRAGMENT
+    /* initialize internal fragmentation capability with known frame size */
+    if (options->ce.fragment && (c->mode == CM_P2P || child))
+    {
+        do_init_fragment(c);
+    }
+#endif
+
+    /* initialize dynamic MTU variable */
+    frame_init_mssfix(&c->c2.frame, &c->options);
+
+    /* bind the TCP/UDP socket */
+    if (c->mode == CM_P2P || c->mode == CM_TOP || c->mode == CM_CHILD_TCP)
+    {
+        do_init_socket_1(c, link_socket_mode);
+    }
+
+    /* initialize tun/tap device object,
+     * open tun/tap device, ifconfig, run up script, etc. */
+    if (!(options->up_delay || PULL_DEFINED(options)) && (c->mode == CM_P2P || c->mode == CM_TOP))
+    {
+        c->c2.did_open_tun = do_open_tun(c);
+    }
+
+    c->c2.frame_initial = c->c2.frame;
+
+    /* print MTU info */
+    do_print_data_channel_mtu_parms(c);
+
+#ifdef ENABLE_OCC
+    /* get local and remote options compatibility strings */
+    if (c->mode == CM_P2P || child)
+    {
+        do_compute_occ_strings(c);
+    }
+#endif
+
+    /* initialize output speed limiter */
+    if (c->mode == CM_P2P)
+    {
+        do_init_traffic_shaper(c);
+    }
+
+    /* do one-time inits, and possibily become a daemon here */
+    do_init_first_time(c);
+
+#ifdef ENABLE_PLUGIN
+    /* initialize plugins */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        open_plugins(c, false, OPENVPN_PLUGIN_INIT_POST_DAEMON);
+    }
+#endif
+
+    /* initialise connect timeout timer */
+    do_init_server_poll_timeout(c);
+
+    /* finalize the TCP/UDP socket */
+    if (c->mode == CM_P2P || c->mode == CM_TOP || c->mode == CM_CHILD_TCP)
+    {
+        do_init_socket_2(c);
+    }
+
+    /*
+     * Actually do UID/GID downgrade, and chroot, if requested.
+     * May be delayed by --client, --pull, or --up-delay.
+     */
+    do_uid_gid_chroot(c, c->c2.did_open_tun);
+
+    /* initialize timers */
+    if (c->mode == CM_P2P || child)
+    {
+        do_init_timers(c, false);
+    }
+
+#ifdef ENABLE_PLUGIN
+    /* initialize plugins */
+    if (c->mode == CM_P2P || c->mode == CM_TOP)
+    {
+        open_plugins(c, false, OPENVPN_PLUGIN_INIT_POST_UID_CHANGE);
+    }
+#endif
+
+#if PORT_SHARE
+    /* share OpenVPN port with foreign (such as HTTPS) server */
+    if (c->first_time && (c->mode == CM_P2P || c->mode == CM_TOP))
+    {
+        init_port_share(c);
+    }
+#endif
+
+#ifdef ENABLE_PF
+    if (child)
+    {
+        pf_init_context(c);
+    }
+#endif
+
+    /* Check for signals */
+    if (IS_SIG(c))
+    {
+        goto sig;
+    }
+
+    return;
+
+sig:
+    if (!c->sig->signal_text)
+    {
+        c->sig->signal_text = "init_instance";
+    }
+    close_context(c, -1, flags);
+    return;
+}
+
+/*
+ * Close a tunnel instance.
+ */
+void
+close_instance(struct context *c)
+{
+    /* close event objects */
+    do_close_event_set(c);
+
+    if (c->mode == CM_P2P
+        || c->mode == CM_CHILD_TCP
+        || c->mode == CM_CHILD_UDP
+        || c->mode == CM_TOP)
+    {
+        /* if xinetd/inetd mode, don't allow restart */
+        do_close_check_if_restart_permitted(c);
+
+#ifdef USE_COMP
+        if (c->c2.comp_context)
+        {
+            comp_uninit(c->c2.comp_context);
+            c->c2.comp_context = NULL;
+        }
+#endif
+
+        /* free buffers */
+        do_close_free_buf(c);
+
+        /* close TLS */
+        do_close_tls(c);
+
+        /* free key schedules */
+        do_close_free_key_schedule(c, (c->mode == CM_P2P || c->mode == CM_TOP));
+
+        restore_ncp_options(c);
+
+        /* close TCP/UDP connection */
+        do_close_link_socket(c);
+
+        /* close TUN/TAP device */
+        do_close_tun(c, false);
+
+#ifdef MANAGEMENT_DEF_AUTH
+        if (management)
+        {
+            management_notify_client_close(management, &c->c2.mda_context, NULL);
+        }
+#endif
+
+#ifdef ENABLE_PF
+        pf_destroy_context(&c->c2.pf);
+#endif
+
+#ifdef ENABLE_PLUGIN
+        /* call plugin close functions and unload */
+        do_close_plugins(c);
+#endif
+
+        /* close packet-id persistance file */
+        do_close_packet_id(c);
+
+        /* close --status file */
+        do_close_status_output(c);
+
+#ifdef ENABLE_FRAGMENT
+        /* close fragmentation handler */
+        do_close_fragment(c);
+#endif
+
+        /* close --ifconfig-pool-persist obj */
+        do_close_ifconfig_pool_persist(c);
+
+        /* free up environmental variable store */
+        do_env_set_destroy(c);
+
+        /* close HTTP or SOCKS proxy */
+        uninit_proxy(c);
+
+        /* garbage collect */
+        gc_free(&c->c2.gc);
+    }
+}
+
+void
+inherit_context_child(struct context *dest,
+                      const struct context *src)
+{
+    CLEAR(*dest);
+
+    /* proto_is_dgram will ASSERT(0) if proto is invalid */
+    dest->mode = proto_is_dgram(src->options.ce.proto) ? CM_CHILD_UDP : CM_CHILD_TCP;
+
+    dest->gc = gc_new();
+
+    ALLOC_OBJ_CLEAR_GC(dest->sig, struct signal_info, &dest->gc);
+
+    /* c1 init */
+    packet_id_persist_init(&dest->c1.pid_persist);
+
+#ifdef ENABLE_CRYPTO
+    dest->c1.ks.key_type = src->c1.ks.key_type;
+    /* inherit SSL context */
+    dest->c1.ks.ssl_ctx = src->c1.ks.ssl_ctx;
+    dest->c1.ks.tls_wrap_key = src->c1.ks.tls_wrap_key;
+    dest->c1.ks.tls_auth_key_type = src->c1.ks.tls_auth_key_type;
+    /* inherit pre-NCP ciphers */
+    dest->c1.ciphername = src->c1.ciphername;
+    dest->c1.authname = src->c1.authname;
+    dest->c1.keysize = src->c1.keysize;
+#endif
+
+    /* options */
+    dest->options = src->options;
+    options_detach(&dest->options);
+
+    if (dest->mode == CM_CHILD_TCP)
+    {
+        /*
+         * The CM_TOP context does the socket listen(),
+         * and the CM_CHILD_TCP context does the accept().
+         */
+        dest->c2.accept_from = src->c2.link_socket;
+    }
+
+#ifdef ENABLE_PLUGIN
+    /* inherit plugins */
+    do_inherit_plugins(dest, src);
+#endif
+
+    /* context init */
+    init_instance(dest, src->c2.es, CC_NO_CLOSE | CC_USR1_TO_HUP);
+    if (IS_SIG(dest))
+    {
+        return;
+    }
+
+    /* inherit tun/tap interface object */
+    dest->c1.tuntap = src->c1.tuntap;
+
+    /* UDP inherits some extra things which TCP does not */
+    if (dest->mode == CM_CHILD_UDP)
+    {
+        /* inherit buffers */
+        dest->c2.buffers = src->c2.buffers;
+
+        /* inherit parent link_socket and tuntap */
+        dest->c2.link_socket = src->c2.link_socket;
+
+        ALLOC_OBJ_GC(dest->c2.link_socket_info, struct link_socket_info, &dest->gc);
+        *dest->c2.link_socket_info = src->c2.link_socket->info;
+
+        /* locally override some link_socket_info fields */
+        dest->c2.link_socket_info->lsa = &dest->c1.link_socket_addr;
+        dest->c2.link_socket_info->connection_established = false;
+    }
+}
+
+void
+inherit_context_top(struct context *dest,
+                    const struct context *src)
+{
+    /* copy parent */
+    *dest = *src;
+
+    /*
+     * CM_TOP_CLONE will prevent close_instance from freeing or closing
+     * resources owned by the parent.
+     *
+     * Also note that CM_TOP_CLONE context objects are
+     * closed by multi_top_free in multi.c.
+     */
+    dest->mode = CM_TOP_CLONE;
+
+    dest->first_time = false;
+    dest->c0 = NULL;
+
+    options_detach(&dest->options);
+    gc_detach(&dest->gc);
+    gc_detach(&dest->c2.gc);
+
+    /* detach plugins */
+    dest->plugins_owned = false;
+
+#ifdef ENABLE_CRYPTO
+    dest->c2.tls_multi = NULL;
+#endif
+
+    /* detach c1 ownership */
+    dest->c1.tuntap_owned = false;
+    dest->c1.status_output_owned = false;
+#if P2MP_SERVER
+    dest->c1.ifconfig_pool_persist_owned = false;
+#endif
+
+    /* detach c2 ownership */
+    dest->c2.event_set_owned = false;
+    dest->c2.link_socket_owned = false;
+    dest->c2.buffers_owned = false;
+    dest->c2.es_owned = false;
+
+    dest->c2.event_set = NULL;
+    if (proto_is_dgram(src->options.ce.proto))
+    {
+        do_event_set_init(dest, false);
+    }
+
+#ifdef USE_COMP
+    dest->c2.comp_context = NULL;
+#endif
+}
+
+void
+close_context(struct context *c, int sig, unsigned int flags)
+{
+    ASSERT(c);
+    ASSERT(c->sig);
+
+    if (sig >= 0)
+    {
+        c->sig->signal_received = sig;
+    }
+
+    if (c->sig->signal_received == SIGUSR1)
+    {
+        if ((flags & CC_USR1_TO_HUP)
+            || (c->sig->source == SIG_SOURCE_HARD && (flags & CC_HARD_USR1_TO_HUP)))
+        {
+            c->sig->signal_received = SIGHUP;
+            c->sig->signal_text = "close_context usr1 to hup";
+        }
+    }
+
+    if (!(flags & CC_NO_CLOSE))
+    {
+        close_instance(c);
+    }
+
+    if (flags & CC_GC_FREE)
+    {
+        context_gc_free(c);
+    }
+}
+
+#ifdef ENABLE_CRYPTO
+
+/*
+ * Do a loopback test
+ * on the crypto subsystem.
+ */
+static void *
+test_crypto_thread(void *arg)
+{
+    struct context *c = (struct context *) arg;
+    const struct options *options = &c->options;
+
+    ASSERT(options->test_crypto);
+    init_verb_mute(c, IVM_LEVEL_1);
+    context_init_1(c);
+    next_connection_entry(c);
+    do_init_crypto_static(c, 0);
+
+    frame_finalize_options(c, options);
+
+    test_crypto(&c->c2.crypto_options, &c->c2.frame);
+
+    key_schedule_free(&c->c1.ks, true);
+    packet_id_free(&c->c2.crypto_options.packet_id);
+
+    context_gc_free(c);
+    return NULL;
+}
+
+#endif /* ENABLE_CRYPTO */
+
+bool
+do_test_crypto(const struct options *o)
+{
+#ifdef ENABLE_CRYPTO
+    if (o->test_crypto)
+    {
+        struct context c;
+
+        /* print version number */
+        msg(M_INFO, "%s", title_string);
+
+        context_clear(&c);
+        c.options = *o;
+        options_detach(&c.options);
+        c.first_time = true;
+        test_crypto_thread((void *) &c);
+        return true;
+    }
+#endif
+    return false;
+}
diff --git a/src/openvpn/init.h b/src/openvpn/init.h
new file mode 100644
index 0000000..2c846db
--- /dev/null
+++ b/src/openvpn/init.h
@@ -0,0 +1,143 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef INIT_H
+#define INIT_H
+
+#include "openvpn.h"
+
+/*
+ * Baseline maximum number of events
+ * to wait for.
+ */
+#define BASE_N_EVENTS 4
+
+void context_clear(struct context *c);
+
+void context_clear_1(struct context *c);
+
+void context_clear_2(struct context *c);
+
+void context_init_1(struct context *c);
+
+void context_clear_all_except_first_time(struct context *c);
+
+bool init_static(void);
+
+void uninit_static(void);
+
+#define IVM_LEVEL_1 (1<<0)
+#define IVM_LEVEL_2 (1<<1)
+void init_verb_mute(struct context *c, unsigned int flags);
+
+void init_options_dev(struct options *options);
+
+bool print_openssl_info(const struct options *options);
+
+bool do_genkey(const struct options *options);
+
+bool do_persist_tuntap(const struct options *options);
+
+bool possibly_become_daemon(const struct options *options);
+
+void pre_setup(const struct options *options);
+
+void init_instance_handle_signals(struct context *c, const struct env_set *env, const unsigned int flags);
+
+void init_instance(struct context *c, const struct env_set *env, const unsigned int flags);
+
+/**
+ * Query for private key and auth-user-pass username/passwords.
+ */
+void init_query_passwords(const struct context *c);
+
+void do_route(const struct options *options,
+              struct route_list *route_list,
+              struct route_ipv6_list *route_ipv6_list,
+              const struct tuntap *tt,
+              const struct plugin_list *plugins,
+              struct env_set *es);
+
+void close_instance(struct context *c);
+
+bool do_test_crypto(const struct options *o);
+
+void context_gc_free(struct context *c);
+
+bool do_up(struct context *c,
+           bool pulled_options,
+           unsigned int option_types_found);
+
+unsigned int pull_permission_mask(const struct context *c);
+
+const char *format_common_name(struct context *c, struct gc_arena *gc);
+
+void reset_coarse_timers(struct context *c);
+
+bool do_deferred_options(struct context *c, const unsigned int found);
+
+void inherit_context_child(struct context *dest,
+                           const struct context *src);
+
+void inherit_context_top(struct context *dest,
+                         const struct context *src);
+
+#define CC_GC_FREE          (1<<0)
+#define CC_USR1_TO_HUP      (1<<1)
+#define CC_HARD_USR1_TO_HUP (1<<2)
+#define CC_NO_CLOSE         (1<<3)
+
+void close_context(struct context *c, int sig, unsigned int flags);
+
+struct context_buffers *init_context_buffers(const struct frame *frame);
+
+void free_context_buffers(struct context_buffers *b);
+
+#define ISC_ERRORS (1<<0)
+#define ISC_SERVER (1<<1)
+void initialization_sequence_completed(struct context *c, const unsigned int flags);
+
+#ifdef ENABLE_MANAGEMENT
+
+void init_management(void);
+
+bool open_management(struct context *c);
+
+void close_management(void);
+
+void management_show_net_callback(void *arg, const int msglevel);
+
+#endif
+
+void init_management_callback_p2p(struct context *c);
+
+void uninit_management_callback(void);
+
+#ifdef ENABLE_PLUGIN
+void init_plugins(struct context *c);
+
+void open_plugins(struct context *c, const bool import_options, int init_point);
+
+#endif
+
+#endif /* ifndef INIT_H */
diff --git a/src/openvpn/integer.h b/src/openvpn/integer.h
new file mode 100644
index 0000000..a7e19d3
--- /dev/null
+++ b/src/openvpn/integer.h
@@ -0,0 +1,153 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef INTEGER_H
+#define INTEGER_H
+
+#include "error.h"
+
+/*
+ * min/max functions
+ */
+
+static inline int
+max_int(int x, int y)
+{
+    if (x > y)
+    {
+        return x;
+    }
+    else
+    {
+        return y;
+    }
+}
+
+static inline int
+min_int(int x, int y)
+{
+    if (x < y)
+    {
+        return x;
+    }
+    else
+    {
+        return y;
+    }
+}
+
+static inline int
+constrain_int(int x, int min, int max)
+{
+    if (min > max)
+    {
+        return min;
+    }
+    if (x < min)
+    {
+        return min;
+    }
+    else if (x > max)
+    {
+        return max;
+    }
+    else
+    {
+        return x;
+    }
+}
+
+/*
+ * Functions used for circular buffer index arithmetic.
+ */
+
+/*
+ * Return x - y on a circle of circumference mod by shortest path.
+ *
+ * 0 <= x < mod
+ * 0 <= y < mod
+ */
+static inline int
+modulo_subtract(int x, int y, int mod)
+{
+    const int d1 = x - y;
+    const int d2 = (x > y ? -mod : mod) + d1;
+    ASSERT(0 <= x && x < mod && 0 <= y && y < mod);
+    return abs(d1) > abs(d2) ? d2 : d1;
+}
+
+/*
+ * Return x + y on a circle of circumference mod.
+ *
+ * 0 <= x < mod
+ * -mod <= y <= mod
+ */
+static inline int
+modulo_add(int x, int y, int mod)
+{
+    int sum = x + y;
+    ASSERT(0 <= x && x < mod && -mod <= y && y <= mod);
+    if (sum >= mod)
+    {
+        sum -= mod;
+    }
+    if (sum < 0)
+    {
+        sum += mod;
+    }
+    return sum;
+}
+
+/*
+ * Return the next largest power of 2
+ * or u if u is a power of 2.
+ */
+static inline size_t
+adjust_power_of_2(size_t u)
+{
+    size_t ret = 1;
+
+    while (ret < u)
+    {
+        ret <<= 1;
+        ASSERT(ret > 0);
+    }
+
+    return ret;
+}
+
+static inline int
+index_verify(int index, int size, const char *file, int line)
+{
+    if (index < 0 || index >= size)
+    {
+        msg(M_FATAL, "Assertion Failed: Array index=%d out of bounds for array size=%d in %s:%d",
+            index,
+            size,
+            file,
+            line);
+    }
+    return index;
+}
+
+#endif /* ifndef INTEGER_H */
diff --git a/src/openvpn/interval.c b/src/openvpn/interval.c
new file mode 100644
index 0000000..b728560
--- /dev/null
+++ b/src/openvpn/interval.c
@@ -0,0 +1,84 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "interval.h"
+
+#include "memdbg.h"
+
+void
+interval_init(struct interval *top, int horizon, int refresh)
+{
+    CLEAR(*top);
+    top->refresh = refresh;
+    top->horizon = horizon;
+}
+
+bool
+event_timeout_trigger(struct event_timeout *et,
+                      struct timeval *tv,
+                      const int et_const_retry)
+{
+    bool ret = false;
+    const time_t local_now = now;
+
+    if (et->defined)
+    {
+        time_t wakeup = et->last - local_now + et->n;
+        if (wakeup <= 0)
+        {
+#if INTERVAL_DEBUG
+            dmsg(D_INTERVAL, "EVENT event_timeout_trigger (%d) etcr=%d", et->n,
+                 et_const_retry);
+#endif
+            if (et_const_retry < 0)
+            {
+                et->last = local_now;
+                wakeup = et->n;
+                ret = true;
+            }
+            else
+            {
+                wakeup = et_const_retry;
+            }
+        }
+
+        if (tv && wakeup < tv->tv_sec)
+        {
+#if INTERVAL_DEBUG
+            dmsg(D_INTERVAL, "EVENT event_timeout_wakeup (%d/%d) etcr=%d",
+                 (int) wakeup, et->n, et_const_retry);
+#endif
+            tv->tv_sec = wakeup;
+            tv->tv_usec = 0;
+        }
+    }
+    return ret;
+}
diff --git a/src/openvpn/interval.h b/src/openvpn/interval.h
new file mode 100644
index 0000000..5623f3a
--- /dev/null
+++ b/src/openvpn/interval.h
@@ -0,0 +1,261 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * The interval_ routines are designed to optimize the calling of a routine
+ * (normally tls_multi_process()) which can be called less frequently
+ * between triggers.
+ */
+
+#ifndef INTERVAL_H
+#define INTERVAL_H
+
+#include "otime.h"
+
+#define INTERVAL_DEBUG 0
+
+/*
+ * Designed to limit calls to expensive functions that need to be called
+ * regularly.
+ */
+
+struct interval
+{
+    interval_t refresh;
+    interval_t horizon;
+    time_t future_trigger;
+    time_t last_action;
+    time_t last_test_true;
+};
+
+void interval_init(struct interval *top, int horizon, int refresh);
+
+/*
+ * IF
+ *   last_action less than horizon seconds ago
+ *   OR last_test_true more than refresh seconds ago
+ *   OR hit future_trigger
+ * THEN
+ *   return true
+ * ELSE
+ *   set wakeup to the number of seconds until a true return
+ *   return false
+ */
+
+static inline bool
+interval_test(struct interval *top)
+{
+    bool trigger = false;
+    const time_t local_now = now;
+
+    if (top->future_trigger && local_now >= top->future_trigger)
+    {
+        trigger = true;
+        top->future_trigger = 0;
+    }
+
+    if (top->last_action + top->horizon > local_now
+        || top->last_test_true + top->refresh <= local_now
+        || trigger)
+    {
+        top->last_test_true = local_now;
+#if INTERVAL_DEBUG
+        dmsg(D_INTERVAL, "INTERVAL interval_test true");
+#endif
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static inline void
+interval_schedule_wakeup(struct interval *top, interval_t *wakeup)
+{
+    const time_t local_now = now;
+    interval_earliest_wakeup(wakeup, top->last_test_true + top->refresh, local_now);
+    interval_earliest_wakeup(wakeup, top->future_trigger, local_now);
+#if INTERVAL_DEBUG
+    dmsg(D_INTERVAL, "INTERVAL interval_schedule wakeup=%d", (int)*wakeup);
+#endif
+}
+
+/*
+ * In wakeup seconds, interval_test will return true once.
+ */
+static inline void
+interval_future_trigger(struct interval *top, interval_t wakeup)
+{
+    if (wakeup)
+    {
+#if INTERVAL_DEBUG
+        dmsg(D_INTERVAL, "INTERVAL interval_future_trigger %d", (int)wakeup);
+#endif
+        top->future_trigger = now + wakeup;
+    }
+}
+
+/*
+ * Once an action is triggered, interval_test will remain true for
+ * horizon seconds.
+ */
+static inline void
+interval_action(struct interval *top)
+{
+#if INTERVAL_DEBUG
+    dmsg(D_INTERVAL, "INTERVAL action");
+#endif
+    top->last_action = now;
+}
+
+/*
+ * Measure when n seconds beyond an event have elapsed
+ */
+
+struct event_timeout
+{
+    bool defined;
+    interval_t n;
+    time_t last; /* time of last event */
+};
+
+static inline bool
+event_timeout_defined(const struct event_timeout *et)
+{
+    return et->defined;
+}
+
+static inline void
+event_timeout_clear(struct event_timeout *et)
+{
+    et->defined = false;
+    et->n = 0;
+    et->last = 0;
+}
+
+static inline struct event_timeout
+event_timeout_clear_ret(void)
+{
+    struct event_timeout ret;
+    event_timeout_clear(&ret);
+    return ret;
+}
+
+static inline void
+event_timeout_init(struct event_timeout *et, interval_t n, const time_t local_now)
+{
+    et->defined = true;
+    et->n = (n >= 0) ? n : 0;
+    et->last = local_now;
+}
+
+static inline void
+event_timeout_reset(struct event_timeout *et)
+{
+    if (et->defined)
+    {
+        et->last = now;
+    }
+}
+
+static inline void
+event_timeout_modify_wakeup(struct event_timeout *et, interval_t n)
+{
+    /* note that you might need to call reset_coarse_timers after this */
+    if (et->defined)
+    {
+        et->n = (n >= 0) ? n : 0;
+    }
+}
+
+/*
+ * Will return the time left for a timeout, this function does not check
+ * if the timeout is actually valid
+ */
+static inline interval_t
+event_timeout_remaining(struct event_timeout *et)
+{
+    return (interval_t) (et->last - now + et->n);
+}
+
+/*
+ * This is the principal function for testing and triggering recurring
+ * timers and will return true on a timer signal event.
+ * If et_const_retry == ETT_DEFAULT and a signal occurs,
+ * the function will return true and *et will be armed for the
+ * next event.  If et_const_retry >= 0 and a signal occurs,
+ * *et will not be touched, but *tv will be set to
+ * minimum (*tv, et_const_retry) for a future re-test,
+ * and the function will return true.
+ */
+
+#define ETT_DEFAULT (-1)
+
+bool event_timeout_trigger(struct event_timeout *et,
+                           struct timeval *tv,
+                           const int et_const_retry);
+
+/*
+ * Measure time intervals in microseconds
+ */
+
+#define USEC_TIMER_MAX      60 /* maximum interval size in seconds */
+
+#define USEC_TIMER_MAX_USEC (USEC_TIMER_MAX * 1000000)
+
+struct usec_timer {
+    struct timeval start;
+    struct timeval end;
+};
+
+#ifdef HAVE_GETTIMEOFDAY
+
+static inline void
+usec_timer_start(struct usec_timer *obj)
+{
+    CLEAR(*obj);
+    openvpn_gettimeofday(&obj->start, NULL);
+}
+
+static inline void
+usec_timer_end(struct usec_timer *obj)
+{
+    openvpn_gettimeofday(&obj->end, NULL);
+}
+
+#endif /* HAVE_GETTIMEOFDAY */
+
+static inline bool
+usec_timer_interval_defined(struct usec_timer *obj)
+{
+    return obj->start.tv_sec && obj->end.tv_sec;
+}
+
+static inline int
+usec_timer_interval(struct usec_timer *obj)
+{
+    return tv_subtract(&obj->end, &obj->start, USEC_TIMER_MAX);
+}
+
+#endif /* INTERVAL_H */
diff --git a/src/openvpn/list.c b/src/openvpn/list.c
new file mode 100644
index 0000000..09e393a
--- /dev/null
+++ b/src/openvpn/list.c
@@ -0,0 +1,677 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "integer.h"
+#include "list.h"
+#include "misc.h"
+
+#include "memdbg.h"
+
+struct hash *
+hash_init(const int n_buckets,
+          const uint32_t iv,
+          uint32_t (*hash_function)(const void *key, uint32_t iv),
+          bool (*compare_function)(const void *key1, const void *key2))
+{
+    struct hash *h;
+    int i;
+
+    ASSERT(n_buckets > 0);
+    ALLOC_OBJ_CLEAR(h, struct hash);
+    h->n_buckets = (int) adjust_power_of_2(n_buckets);
+    h->mask = h->n_buckets - 1;
+    h->hash_function = hash_function;
+    h->compare_function = compare_function;
+    h->iv = iv;
+    ALLOC_ARRAY(h->buckets, struct hash_bucket, h->n_buckets);
+    for (i = 0; i < h->n_buckets; ++i)
+    {
+        struct hash_bucket *b = &h->buckets[i];
+        b->list = NULL;
+    }
+    return h;
+}
+
+void
+hash_free(struct hash *hash)
+{
+    int i;
+    for (i = 0; i < hash->n_buckets; ++i)
+    {
+        struct hash_bucket *b = &hash->buckets[i];
+        struct hash_element *he = b->list;
+
+        while (he)
+        {
+            struct hash_element *next = he->next;
+            free(he);
+            he = next;
+        }
+    }
+    free(hash->buckets);
+    free(hash);
+}
+
+struct hash_element *
+hash_lookup_fast(struct hash *hash,
+                 struct hash_bucket *bucket,
+                 const void *key,
+                 uint32_t hv)
+{
+    struct hash_element *he;
+    struct hash_element *prev = NULL;
+
+    he = bucket->list;
+
+    while (he)
+    {
+        if (hv == he->hash_value && (*hash->compare_function)(key, he->key))
+        {
+            /* move to head of list */
+            if (prev)
+            {
+                prev->next = he->next;
+                he->next = bucket->list;
+                bucket->list = he;
+            }
+            return he;
+        }
+        prev = he;
+        he = he->next;
+    }
+
+    return NULL;
+}
+
+bool
+hash_remove_fast(struct hash *hash,
+                 struct hash_bucket *bucket,
+                 const void *key,
+                 uint32_t hv)
+{
+    struct hash_element *he;
+    struct hash_element *prev = NULL;
+
+    he = bucket->list;
+
+    while (he)
+    {
+        if (hv == he->hash_value && (*hash->compare_function)(key, he->key))
+        {
+            if (prev)
+            {
+                prev->next = he->next;
+            }
+            else
+            {
+                bucket->list = he->next;
+            }
+            free(he);
+            --hash->n_elements;
+            return true;
+        }
+        prev = he;
+        he = he->next;
+    }
+    return false;
+}
+
+bool
+hash_add(struct hash *hash, const void *key, void *value, bool replace)
+{
+    uint32_t hv;
+    struct hash_bucket *bucket;
+    struct hash_element *he;
+    bool ret = false;
+
+    hv = hash_value(hash, key);
+    bucket = &hash->buckets[hv & hash->mask];
+
+    if ((he = hash_lookup_fast(hash, bucket, key, hv))) /* already exists? */
+    {
+        if (replace)
+        {
+            he->value = value;
+            ret = true;
+        }
+    }
+    else
+    {
+        hash_add_fast(hash, bucket, key, hv, value);
+        ret = true;
+    }
+
+    return ret;
+}
+
+void
+hash_remove_by_value(struct hash *hash, void *value)
+{
+    struct hash_iterator hi;
+    struct hash_element *he;
+
+    hash_iterator_init(hash, &hi);
+    while ((he = hash_iterator_next(&hi)))
+    {
+        if (he->value == value)
+        {
+            hash_iterator_delete_element(&hi);
+        }
+    }
+    hash_iterator_free(&hi);
+}
+
+static void
+hash_remove_marked(struct hash *hash, struct hash_bucket *bucket)
+{
+    struct hash_element *prev = NULL;
+    struct hash_element *he = bucket->list;
+
+    while (he)
+    {
+        if (!he->key) /* marked? */
+        {
+            struct hash_element *newhe;
+            if (prev)
+            {
+                newhe = prev->next = he->next;
+            }
+            else
+            {
+                newhe = bucket->list = he->next;
+            }
+            free(he);
+            --hash->n_elements;
+            he = newhe;
+        }
+        else
+        {
+            prev = he;
+            he = he->next;
+        }
+    }
+}
+
+uint32_t
+void_ptr_hash_function(const void *key, uint32_t iv)
+{
+    return hash_func((const void *)&key, sizeof(key), iv);
+}
+
+bool
+void_ptr_compare_function(const void *key1, const void *key2)
+{
+    return key1 == key2;
+}
+
+void
+hash_iterator_init_range(struct hash *hash,
+                         struct hash_iterator *hi,
+                         int start_bucket,
+                         int end_bucket)
+{
+    if (end_bucket > hash->n_buckets)
+    {
+        end_bucket = hash->n_buckets;
+    }
+
+    ASSERT(start_bucket >= 0 && start_bucket <= end_bucket);
+
+    hi->hash = hash;
+    hi->elem = NULL;
+    hi->bucket = NULL;
+    hi->last = NULL;
+    hi->bucket_marked = false;
+    hi->bucket_index_start = start_bucket;
+    hi->bucket_index_end = end_bucket;
+    hi->bucket_index = hi->bucket_index_start - 1;
+}
+
+void
+hash_iterator_init(struct hash *hash,
+                   struct hash_iterator *hi)
+{
+    hash_iterator_init_range(hash, hi, 0, hash->n_buckets);
+}
+
+static inline void
+hash_iterator_lock(struct hash_iterator *hi, struct hash_bucket *b)
+{
+    hi->bucket = b;
+    hi->last = NULL;
+    hi->bucket_marked = false;
+}
+
+static inline void
+hash_iterator_unlock(struct hash_iterator *hi)
+{
+    if (hi->bucket)
+    {
+        if (hi->bucket_marked)
+        {
+            hash_remove_marked(hi->hash, hi->bucket);
+            hi->bucket_marked = false;
+        }
+        hi->bucket = NULL;
+        hi->last = NULL;
+    }
+}
+
+static inline void
+hash_iterator_advance(struct hash_iterator *hi)
+{
+    hi->last = hi->elem;
+    hi->elem = hi->elem->next;
+}
+
+void
+hash_iterator_free(struct hash_iterator *hi)
+{
+    hash_iterator_unlock(hi);
+}
+
+struct hash_element *
+hash_iterator_next(struct hash_iterator *hi)
+{
+    struct hash_element *ret = NULL;
+    if (hi->elem)
+    {
+        ret = hi->elem;
+        hash_iterator_advance(hi);
+    }
+    else
+    {
+        while (++hi->bucket_index < hi->bucket_index_end)
+        {
+            struct hash_bucket *b;
+            hash_iterator_unlock(hi);
+            b = &hi->hash->buckets[hi->bucket_index];
+            if (b->list)
+            {
+                hash_iterator_lock(hi, b);
+                hi->elem = b->list;
+                if (hi->elem)
+                {
+                    ret = hi->elem;
+                    hash_iterator_advance(hi);
+                    break;
+                }
+            }
+        }
+    }
+    return ret;
+}
+
+void
+hash_iterator_delete_element(struct hash_iterator *hi)
+{
+    ASSERT(hi->last);
+    hi->last->key = NULL;
+    hi->bucket_marked = true;
+}
+
+
+#ifdef LIST_TEST
+
+/*
+ * Test the hash code by implementing a simple
+ * word frequency algorithm.
+ */
+
+struct word
+{
+    const char *word;
+    int n;
+};
+
+static uint32_t
+word_hash_function(const void *key, uint32_t iv)
+{
+    const char *str = (const char *) key;
+    const int len = strlen(str);
+    return hash_func((const uint8_t *)str, len, iv);
+}
+
+static bool
+word_compare_function(const void *key1, const void *key2)
+{
+    return strcmp((const char *)key1, (const char *)key2) == 0;
+}
+
+static void
+print_nhash(struct hash *hash)
+{
+    struct hash_iterator hi;
+    struct hash_element *he;
+    int count = 0;
+
+    hash_iterator_init(hash, &hi, true);
+
+    while ((he = hash_iterator_next(&hi)))
+    {
+        printf("%d ", (int) he->value);
+        ++count;
+    }
+    printf("\n");
+
+    hash_iterator_free(&hi);
+    ASSERT(count == hash_n_elements(hash));
+}
+
+static void
+rmhash(struct hash *hash, const char *word)
+{
+    hash_remove(hash, word);
+}
+
+void
+list_test(void)
+{
+    openvpn_thread_init();
+
+    {
+        struct gc_arena gc = gc_new();
+        struct hash *hash = hash_init(10000, get_random(), word_hash_function, word_compare_function);
+        struct hash *nhash = hash_init(256, get_random(), word_hash_function, word_compare_function);
+
+        printf("hash_init n_buckets=%d mask=0x%08x\n", hash->n_buckets, hash->mask);
+
+        /* parse words from stdin */
+        while (true)
+        {
+            char buf[256];
+            char wordbuf[256];
+            int wbi;
+            int bi;
+            char c;
+
+            if (!fgets(buf, sizeof(buf), stdin))
+            {
+                break;
+            }
+
+            bi = wbi = 0;
+            do
+            {
+                c = buf[bi++];
+                if (isalnum(c) || c == '_')
+                {
+                    ASSERT(wbi < (int) sizeof(wordbuf));
+                    wordbuf[wbi++] = c;
+                }
+                else
+                {
+                    if (wbi)
+                    {
+                        struct word *w;
+                        ASSERT(wbi < (int) sizeof(wordbuf));
+                        wordbuf[wbi++] = '\0';
+
+                        /* word is parsed from stdin */
+
+                        /* does it already exist in table? */
+                        w = (struct word *) hash_lookup(hash, wordbuf);
+
+                        if (w)
+                        {
+                            /* yes, increment count */
+                            ++w->n;
+                        }
+                        else
+                        {
+                            /* no, make a new object */
+                            ALLOC_OBJ_GC(w, struct word, &gc);
+                            w->word = string_alloc(wordbuf, &gc);
+                            w->n = 1;
+                            ASSERT(hash_add(hash, w->word, w, false));
+                            ASSERT(hash_add(nhash, w->word, (void *) ((random() & 0x0F) + 1), false));
+                        }
+                    }
+                    wbi = 0;
+                }
+            } while (c);
+        }
+
+#if 1
+        /* remove some words from the table */
+        {
+            rmhash(hash, "true");
+            rmhash(hash, "false");
+        }
+#endif
+
+        /* output contents of hash table */
+        {
+            int base;
+            int inc = 0;
+            int count = 0;
+
+            for (base = 0; base < hash_n_buckets(hash); base += inc)
+            {
+                struct hash_iterator hi;
+                struct hash_element *he;
+                inc = (get_random() % 3) + 1;
+                hash_iterator_init_range(hash, &hi, true, base, base + inc);
+
+                while ((he = hash_iterator_next(&hi)))
+                {
+                    struct word *w = (struct word *) he->value;
+                    printf("%6d '%s'\n", w->n, w->word);
+                    ++count;
+                }
+
+                hash_iterator_free(&hi);
+            }
+            ASSERT(count == hash_n_elements(hash));
+        }
+
+#if 1
+        /* test hash_remove_by_value function */
+        {
+            int i;
+            for (i = 1; i <= 16; ++i)
+            {
+                printf("[%d] ***********************************\n", i);
+                print_nhash(nhash);
+                hash_remove_by_value(nhash, (void *) i, true);
+            }
+            printf("FINAL **************************\n");
+            print_nhash(nhash);
+        }
+#endif
+
+        hash_free(hash);
+        hash_free(nhash);
+        gc_free(&gc);
+    }
+
+    openvpn_thread_cleanup();
+}
+
+#endif /* ifdef LIST_TEST */
+
+/*
+ * --------------------------------------------------------------------
+ * hash() -- hash a variable-length key into a 32-bit value
+ * k     : the key (the unaligned variable-length array of bytes)
+ * len   : the length of the key, counting by bytes
+ * level : can be any 4-byte value
+ * Returns a 32-bit value.  Every bit of the key affects every bit of
+ * the return value.  Every 1-bit and 2-bit delta achieves avalanche.
+ * About 36+6len instructions.
+ *
+ * The best hash table sizes are powers of 2.  There is no need to do
+ * mod a prime (mod is sooo slow!).  If you need less than 32 bits,
+ * use a bitmask.  For example, if you need only 10 bits, do
+ * h = (h & hashmask(10));
+ * In which case, the hash table should have hashsize(10) elements.
+ *
+ * If you are hashing n strings (uint8_t **)k, do it like this:
+ * for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
+ *
+ * By Bob Jenkins, 1996.  bob_jenkins@burtleburtle.net.  You may use this
+ * code any way you wish, private, educational, or commercial.  It's free.
+ *
+ * See http://burlteburtle.net/bob/hash/evahash.html
+ * Use for hash table lookup, or anything where one collision in 2^32 is
+ * acceptable.  Do NOT use for cryptographic purposes.
+ *
+ * --------------------------------------------------------------------
+ *
+ * mix -- mix 3 32-bit values reversibly.
+ * For every delta with one or two bit set, and the deltas of all three
+ * high bits or all three low bits, whether the original value of a,b,c
+ * is almost all zero or is uniformly distributed,
+ * If mix() is run forward or backward, at least 32 bits in a,b,c
+ * have at least 1/4 probability of changing.
+ * If mix() is run forward, every bit of c will change between 1/3 and
+ * 2/3 of the time.  (Well, 22/100 and 78/100 for some 2-bit deltas.)
+ * mix() was built out of 36 single-cycle latency instructions in a
+ * structure that could supported 2x parallelism, like so:
+ *    a -= b;
+ *    a -= c; x = (c>>13);
+ *    b -= c; a ^= x;
+ *    b -= a; x = (a<<8);
+ *    c -= a; b ^= x;
+ *    c -= b; x = (b>>13);
+ *    ...
+ * Unfortunately, superscalar Pentiums and Sparcs can't take advantage
+ * of that parallelism.  They've also turned some of those single-cycle
+ * latency instructions into multi-cycle latency instructions.  Still,
+ * this is the fastest good hash I could find.  There were about 2^^68
+ * to choose from.  I only looked at a billion or so.
+ *
+ * James Yonan Notes:
+ *
+ * This function is faster than it looks, and appears to be
+ * appropriate for our usage in OpenVPN which is primarily
+ * for hash-table based address lookup (IPv4, IPv6, and Ethernet MAC).
+ * NOTE: This function is never used for cryptographic purposes, only
+ * to produce evenly-distributed indexes into hash tables.
+ *
+ * Benchmark results: 11.39 machine cycles per byte on a P2 266Mhz,
+ *                   and 12.1 machine cycles per byte on a
+ *                   2.2 Ghz P4 when hashing a 6 byte string.
+ * --------------------------------------------------------------------
+ */
+
+#define mix(a,b,c)               \
+    {                                \
+        a -= b; a -= c; a ^= (c>>13);  \
+        b -= c; b -= a; b ^= (a<<8);   \
+        c -= a; c -= b; c ^= (b>>13);  \
+        a -= b; a -= c; a ^= (c>>12);  \
+        b -= c; b -= a; b ^= (a<<16);  \
+        c -= a; c -= b; c ^= (b>>5);   \
+        a -= b; a -= c; a ^= (c>>3);   \
+        b -= c; b -= a; b ^= (a<<10);  \
+        c -= a; c -= b; c ^= (b>>15);  \
+    }
+
+uint32_t
+hash_func(const uint8_t *k, uint32_t length, uint32_t initval)
+{
+    uint32_t a, b, c, len;
+
+    /* Set up the internal state */
+    len = length;
+    a = b = 0x9e3779b9;      /* the golden ratio; an arbitrary value */
+    c = initval;             /* the previous hash value */
+
+    /*---------------------------------------- handle most of the key */
+    while (len >= 12)
+    {
+        a += (k[0] + ((uint32_t) k[1] << 8)
+              + ((uint32_t) k[2] << 16)
+              + ((uint32_t) k[3] << 24));
+        b += (k[4] + ((uint32_t) k[5] << 8)
+              + ((uint32_t) k[6] << 16)
+              + ((uint32_t) k[7] << 24));
+        c += (k[8] + ((uint32_t) k[9] << 8)
+              + ((uint32_t) k[10] << 16)
+              + ((uint32_t) k[11] << 24));
+        mix(a, b, c);
+        k += 12;
+        len -= 12;
+    }
+
+    /*------------------------------------- handle the last 11 bytes */
+    c += length;
+    switch (len)            /* all the case statements fall through */
+    {
+        case 11:
+            c += ((uint32_t) k[10] << 24);
+
+        case 10:
+            c += ((uint32_t) k[9] << 16);
+
+        case 9:
+            c += ((uint32_t) k[8] << 8);
+
+        /* the first byte of c is reserved for the length */
+        case 8:
+            b += ((uint32_t) k[7] << 24);
+
+        case 7:
+            b += ((uint32_t) k[6] << 16);
+
+        case 6:
+            b += ((uint32_t) k[5] << 8);
+
+        case 5:
+            b += k[4];
+
+        case 4:
+            a += ((uint32_t) k[3] << 24);
+
+        case 3:
+            a += ((uint32_t) k[2] << 16);
+
+        case 2:
+            a += ((uint32_t) k[1] << 8);
+
+        case 1:
+            a += k[0];
+            /* case 0: nothing left to add */
+    }
+    mix(a, b, c);
+    /*-------------------------------------- report the result */
+    return c;
+}
+
+#else  /* if P2MP_SERVER */
+static void
+dummy(void)
+{
+}
+#endif /* P2MP_SERVER */
diff --git a/src/openvpn/list.h b/src/openvpn/list.h
new file mode 100644
index 0000000..b67301c
--- /dev/null
+++ b/src/openvpn/list.h
@@ -0,0 +1,202 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef LIST_H
+#define LIST_H
+
+/*
+ * This code is a fairly straightforward hash
+ * table implementation using Bob Jenkins'
+ * hash function.
+ *
+ * Hash tables are used in OpenVPN to keep track of
+ * client instances over various key spaces.
+ */
+
+#if P2MP_SERVER
+
+/* define this to enable special list test mode */
+/*#define LIST_TEST*/
+
+#include "basic.h"
+#include "buffer.h"
+
+#define hashsize(n) ((uint32_t)1<<(n))
+#define hashmask(n) (hashsize(n)-1)
+
+struct hash_element
+{
+    void *value;
+    const void *key;
+    unsigned int hash_value;
+    struct hash_element *next;
+};
+
+struct hash_bucket
+{
+    struct hash_element *list;
+};
+
+struct hash
+{
+    int n_buckets;
+    int n_elements;
+    int mask;
+    uint32_t iv;
+    uint32_t (*hash_function)(const void *key, uint32_t iv);
+    bool (*compare_function)(const void *key1, const void *key2); /* return true if equal */
+    struct hash_bucket *buckets;
+};
+
+struct hash *hash_init(const int n_buckets,
+                       const uint32_t iv,
+                       uint32_t (*hash_function)(const void *key, uint32_t iv),
+                       bool (*compare_function)(const void *key1, const void *key2));
+
+void hash_free(struct hash *hash);
+
+bool hash_add(struct hash *hash, const void *key, void *value, bool replace);
+
+struct hash_element *hash_lookup_fast(struct hash *hash,
+                                      struct hash_bucket *bucket,
+                                      const void *key,
+                                      uint32_t hv);
+
+bool hash_remove_fast(struct hash *hash,
+                      struct hash_bucket *bucket,
+                      const void *key,
+                      uint32_t hv);
+
+void hash_remove_by_value(struct hash *hash, void *value);
+
+struct hash_iterator
+{
+    struct hash *hash;
+    int bucket_index;
+    struct hash_bucket *bucket;
+    struct hash_element *elem;
+    struct hash_element *last;
+    bool bucket_marked;
+    int bucket_index_start;
+    int bucket_index_end;
+};
+
+void hash_iterator_init_range(struct hash *hash,
+                              struct hash_iterator *hi,
+                              int start_bucket,
+                              int end_bucket);
+
+void hash_iterator_init(struct hash *hash, struct hash_iterator *iter);
+
+struct hash_element *hash_iterator_next(struct hash_iterator *hi);
+
+void hash_iterator_delete_element(struct hash_iterator *hi);
+
+void hash_iterator_free(struct hash_iterator *hi);
+
+uint32_t hash_func(const uint8_t *k, uint32_t length, uint32_t initval);
+
+uint32_t void_ptr_hash_function(const void *key, uint32_t iv);
+
+bool void_ptr_compare_function(const void *key1, const void *key2);
+
+#ifdef LIST_TEST
+void list_test(void);
+
+#endif
+
+static inline uint32_t
+hash_value(const struct hash *hash, const void *key)
+{
+    return (*hash->hash_function)(key, hash->iv);
+}
+
+static inline int
+hash_n_elements(const struct hash *hash)
+{
+    return hash->n_elements;
+}
+
+static inline int
+hash_n_buckets(const struct hash *hash)
+{
+    return hash->n_buckets;
+}
+
+static inline struct hash_bucket *
+hash_bucket(struct hash *hash, uint32_t hv)
+{
+    return &hash->buckets[hv & hash->mask];
+}
+
+static inline void *
+hash_lookup(struct hash *hash, const void *key)
+{
+    void *ret = NULL;
+    struct hash_element *he;
+    uint32_t hv = hash_value(hash, key);
+    struct hash_bucket *bucket = &hash->buckets[hv & hash->mask];
+
+    he = hash_lookup_fast(hash, bucket, key, hv);
+    if (he)
+    {
+        ret = he->value;
+    }
+
+    return ret;
+}
+
+/* NOTE: assumes that key is not a duplicate */
+static inline void
+hash_add_fast(struct hash *hash,
+              struct hash_bucket *bucket,
+              const void *key,
+              uint32_t hv,
+              void *value)
+{
+    struct hash_element *he;
+
+    ALLOC_OBJ(he, struct hash_element);
+    he->value = value;
+    he->key = key;
+    he->hash_value = hv;
+    he->next = bucket->list;
+    bucket->list = he;
+    ++hash->n_elements;
+}
+
+static inline bool
+hash_remove(struct hash *hash, const void *key)
+{
+    uint32_t hv;
+    struct hash_bucket *bucket;
+    bool ret;
+
+    hv = hash_value(hash, key);
+    bucket = &hash->buckets[hv & hash->mask];
+    ret = hash_remove_fast(hash, bucket, key, hv);
+    return ret;
+}
+
+#endif /* P2MP_SERVER */
+#endif /* LIST */
diff --git a/src/openvpn/lladdr.c b/src/openvpn/lladdr.c
new file mode 100644
index 0000000..ff71e48
--- /dev/null
+++ b/src/openvpn/lladdr.c
@@ -0,0 +1,72 @@
+/*
+ * Support routine for configuring link layer address
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "error.h"
+#include "misc.h"
+
+int
+set_lladdr(const char *ifname, const char *lladdr,
+           const struct env_set *es)
+{
+    struct argv argv = argv_new();
+    int r;
+
+    if (!ifname || !lladdr)
+    {
+        return -1;
+    }
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+    argv_printf(&argv,
+                "%s link set addr %s dev %s",
+                iproute_path, lladdr, ifname);
+#else
+    argv_printf(&argv,
+                "%s %s hw ether %s",
+                IFCONFIG_PATH,
+                ifname, lladdr);
+#endif
+#elif defined(TARGET_SOLARIS)
+    argv_printf(&argv,
+                "%s %s ether %s",
+                IFCONFIG_PATH,
+                ifname, lladdr);
+#elif defined(TARGET_OPENBSD)
+    argv_printf(&argv,
+                "%s %s lladdr %s",
+                IFCONFIG_PATH,
+                ifname, lladdr);
+#elif defined(TARGET_DARWIN)
+    argv_printf(&argv,
+                "%s %s lladdr %s",
+                IFCONFIG_PATH,
+                ifname, lladdr);
+#elif defined(TARGET_FREEBSD)
+    argv_printf(&argv,
+                "%s %s ether %s",
+                IFCONFIG_PATH,
+                ifname, lladdr);
+#else  /* if defined(TARGET_LINUX) */
+    msg(M_WARN, "Sorry, but I don't know how to configure link layer addresses on this operating system.");
+    return -1;
+#endif /* if defined(TARGET_LINUX) */
+
+    argv_msg(M_INFO, &argv);
+    r = openvpn_execve_check(&argv, es, M_WARN, "ERROR: Unable to set link layer address.");
+    if (r)
+    {
+        msg(M_INFO, "TUN/TAP link layer address set to %s", lladdr);
+    }
+
+    argv_reset(&argv);
+    return r;
+}
diff --git a/src/openvpn/lladdr.h b/src/openvpn/lladdr.h
new file mode 100644
index 0000000..f6ea2b1
--- /dev/null
+++ b/src/openvpn/lladdr.h
@@ -0,0 +1,8 @@
+/*
+ * Support routine for configuring link layer address
+ */
+
+#include "misc.h"
+
+int set_lladdr(const char *ifname, const char *lladdr,
+               const struct env_set *es);
diff --git a/src/openvpn/lzo.c b/src/openvpn/lzo.c
new file mode 100644
index 0000000..8d9efea
--- /dev/null
+++ b/src/openvpn/lzo.c
@@ -0,0 +1,272 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Data Channel Compression module function definitions.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_LZO)
+
+#include "comp.h"
+#include "error.h"
+#include "otime.h"
+
+#include "memdbg.h"
+
+/**
+ * Perform adaptive compression housekeeping.
+ *
+ * @param ac the adaptive compression state structure.
+ *
+ * @return
+ */
+static bool
+lzo_adaptive_compress_test(struct lzo_adaptive_compress *ac)
+{
+    const bool save = ac->compress_state;
+    const time_t local_now = now;
+
+    if (!ac->compress_state)
+    {
+        if (local_now >= ac->next)
+        {
+            if (ac->n_total > AC_MIN_BYTES
+                && (ac->n_total - ac->n_comp) < (ac->n_total / (100 / AC_SAVE_PCT)))
+            {
+                ac->compress_state = true;
+                ac->next = local_now + AC_OFF_SEC;
+            }
+            else
+            {
+                ac->next = local_now + AC_SAMP_SEC;
+            }
+            dmsg(D_COMP, "lzo_adaptive_compress_test: comp=%d total=%d", ac->n_comp, ac->n_total);
+            ac->n_total = ac->n_comp = 0;
+        }
+    }
+    else
+    {
+        if (local_now >= ac->next)
+        {
+            ac->next = local_now + AC_SAMP_SEC;
+            ac->n_total = ac->n_comp = 0;
+            ac->compress_state = false;
+        }
+    }
+
+    if (ac->compress_state != save)
+    {
+        dmsg(D_COMP_LOW, "Adaptive compression state %s", (ac->compress_state ? "OFF" : "ON"));
+    }
+
+    return !ac->compress_state;
+}
+
+static inline void
+lzo_adaptive_compress_data(struct lzo_adaptive_compress *ac, int n_total, int n_comp)
+{
+    ac->n_total += n_total;
+    ac->n_comp += n_comp;
+}
+
+static void
+lzo_compress_init(struct compress_context *compctx)
+{
+    msg(D_INIT_MEDIUM, "LZO compression initializing");
+    ASSERT(!(compctx->flags & COMP_F_SWAP));
+    compctx->wu.lzo.wmem_size = LZO_WORKSPACE;
+    if (lzo_init() != LZO_E_OK)
+    {
+        msg(M_FATAL, "Cannot initialize LZO compression library");
+    }
+    compctx->wu.lzo.wmem = (lzo_voidp) lzo_malloc(compctx->wu.lzo.wmem_size);
+    check_malloc_return(compctx->wu.lzo.wmem);
+}
+
+static void
+lzo_compress_uninit(struct compress_context *compctx)
+{
+    lzo_free(compctx->wu.lzo.wmem);
+    compctx->wu.lzo.wmem = NULL;
+}
+
+static inline bool
+lzo_compression_enabled(struct compress_context *compctx)
+{
+    if (compctx->flags & COMP_F_ASYM)
+    {
+        return false;
+    }
+    else
+    {
+        if (compctx->flags & COMP_F_ADAPTIVE)
+        {
+            return lzo_adaptive_compress_test(&compctx->wu.lzo.ac);
+        }
+        else
+        {
+            return true;
+        }
+    }
+}
+
+static void
+lzo_compress(struct buffer *buf, struct buffer work,
+             struct compress_context *compctx,
+             const struct frame *frame)
+{
+    lzo_uint zlen = 0;
+    int err;
+    bool compressed = false;
+
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    /*
+     * In order to attempt compression, length must be at least COMPRESS_THRESHOLD,
+     * and our adaptive level must give the OK.
+     */
+    if (buf->len >= COMPRESS_THRESHOLD && lzo_compression_enabled(compctx))
+    {
+        const size_t ps = PAYLOAD_SIZE(frame);
+        ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
+        ASSERT(buf_safe(&work, ps + COMP_EXTRA_BUFFER(ps)));
+
+        if (buf->len > ps)
+        {
+            dmsg(D_COMP_ERRORS, "LZO compression buffer overflow");
+            buf->len = 0;
+            return;
+        }
+
+        err = LZO_COMPRESS(BPTR(buf), BLEN(buf), BPTR(&work), &zlen, compctx->wu.lzo.wmem);
+        if (err != LZO_E_OK)
+        {
+            dmsg(D_COMP_ERRORS, "LZO compression error: %d", err);
+            buf->len = 0;
+            return;
+        }
+
+        ASSERT(buf_safe(&work, zlen));
+        work.len = zlen;
+        compressed = true;
+
+        dmsg(D_COMP, "LZO compress %d -> %d", buf->len, work.len);
+        compctx->pre_compress += buf->len;
+        compctx->post_compress += work.len;
+
+        /* tell adaptive level about our success or lack thereof in getting any size reduction */
+        if (compctx->flags & COMP_F_ADAPTIVE)
+        {
+            lzo_adaptive_compress_data(&compctx->wu.lzo.ac, buf->len, work.len);
+        }
+    }
+
+    /* did compression save us anything ? */
+    if (compressed && work.len < buf->len)
+    {
+        uint8_t *header = buf_prepend(&work, 1);
+        *header = LZO_COMPRESS_BYTE;
+        *buf = work;
+    }
+    else
+    {
+        uint8_t *header = buf_prepend(buf, 1);
+        *header = NO_COMPRESS_BYTE;
+    }
+}
+
+static void
+lzo_decompress(struct buffer *buf, struct buffer work,
+               struct compress_context *compctx,
+               const struct frame *frame)
+{
+    lzo_uint zlen = EXPANDED_SIZE(frame);
+    int err;
+    uint8_t c;          /* flag indicating whether or not our peer compressed */
+
+    if (buf->len <= 0)
+    {
+        return;
+    }
+
+    ASSERT(buf_init(&work, FRAME_HEADROOM(frame)));
+
+    c = *BPTR(buf);
+    ASSERT(buf_advance(buf, 1));
+
+    if (c == LZO_COMPRESS_BYTE) /* packet was compressed */
+    {
+        ASSERT(buf_safe(&work, zlen));
+        err = LZO_DECOMPRESS(BPTR(buf), BLEN(buf), BPTR(&work), &zlen,
+                             compctx->wu.lzo.wmem);
+        if (err != LZO_E_OK)
+        {
+            dmsg(D_COMP_ERRORS, "LZO decompression error: %d", err);
+            buf->len = 0;
+            return;
+        }
+
+        ASSERT(buf_safe(&work, zlen));
+        work.len = zlen;
+
+        dmsg(D_COMP, "LZO decompress %d -> %d", buf->len, work.len);
+        compctx->pre_decompress += buf->len;
+        compctx->post_decompress += work.len;
+
+        *buf = work;
+    }
+    else if (c == NO_COMPRESS_BYTE)     /* packet was not compressed */
+    {
+    }
+    else
+    {
+        dmsg(D_COMP_ERRORS, "Bad LZO decompression header byte: %d", c);
+        buf->len = 0;
+    }
+}
+
+const struct compress_alg lzo_alg = {
+    "lzo",
+    lzo_compress_init,
+    lzo_compress_uninit,
+    lzo_compress,
+    lzo_decompress
+};
+
+#else  /* if defined(ENABLE_LZO) */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_LZO */
diff --git a/src/openvpn/lzo.h b/src/openvpn/lzo.h
new file mode 100644
index 0000000..11e1c39
--- /dev/null
+++ b/src/openvpn/lzo.h
@@ -0,0 +1,130 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_LZO_H
+#define OPENVPN_LZO_H
+
+
+/**
+ * @file
+ * Data Channel Compression module header file.
+ */
+
+
+#if defined(ENABLE_LZO)
+
+/**
+ * @addtogroup compression
+ * @{
+ */
+
+#if defined(HAVE_LZO_LZOUTIL_H)
+#include "lzo/lzoutil.h"
+#elif defined(HAVE_LZOUTIL_H)
+#include "lzoutil.h"
+#endif
+#if defined(HAVE_LZO_LZO1X_H)
+#include "lzo/lzo1x.h"
+#elif defined(HAVE_LZO1X_H)
+#include "lzo1x.h"
+#endif
+
+#include "buffer.h"
+#include "mtu.h"
+#include "common.h"
+#include "status.h"
+
+extern const struct compress_alg lzo_alg;
+
+/**************************************************************************/
+/** @name LZO library interface defines *//** @{ *//***********************/
+#define LZO_COMPRESS    lzo1x_1_15_compress
+/**< LZO library compression function.
+ *
+ *   Use \c lzo1x_1_15_compress because it
+ *   is described as faster than the
+ *   standard routine, although it does
+ *   need a bit more memory. */
+#define LZO_WORKSPACE   LZO1X_1_15_MEM_COMPRESS
+/**< The size in bytes of the memory
+ *   %buffer required by the LZO library
+ *   compression algorithm. */
+#define LZO_DECOMPRESS  lzo1x_decompress_safe
+/**< LZO library decompression function.
+ *
+ *   Use safe decompress because it
+ *   includes checks for possible %buffer
+ *   overflows. If speed is essential and
+ *   you will always be using a MAC to
+ *   verify the integrity of incoming
+ *   packets, you might want to consider
+ *   using the non-safe version. */
+/** @} name LZO library interface *//**************************************/
+
+
+/**************************************************************************/
+/** @name Adaptive compression defines *//** @{ *//************************/
+#define AC_SAMP_SEC    2        /**< Number of seconds in a sample period. */
+#define AC_MIN_BYTES   1000     /**< Minimum number of bytes a sample
+                                 *   period must contain for it to be
+                                 *   evaluated. */
+#define AC_SAVE_PCT    5        /**< Minimum size reduction percentage
+                                 *   below which compression will be
+                                 *   turned off. */
+#define AC_OFF_SEC     60       /**< Seconds to wait after compression has
+                                 *   been turned off before retesting. */
+/** @} name Adaptive compression defines *//*******************************/
+
+/**
+ * Adaptive compression state.
+ */
+struct lzo_adaptive_compress {
+    bool compress_state;
+    time_t next;
+    int n_total;
+    int n_comp;
+};
+
+
+/**
+ * State for the compression and decompression routines.
+ *
+ * This structure contains compression module state, such as whether
+ * compression is enabled and the status of the adaptive compression
+ * routines.  It also contains an allocated working buffer.
+ *
+ * One of these compression workspace structures is maintained for each
+ * VPN tunnel.
+ */
+struct lzo_compress_workspace
+{
+    lzo_voidp wmem;
+    int wmem_size;
+    struct lzo_adaptive_compress ac;
+};
+
+/** @} addtogroup compression */
+
+
+#endif /* ENABLE_LZO && USE_COMP */
+#endif /* ifndef OPENVPN_LZO_H */
diff --git a/src/openvpn/manage.c b/src/openvpn/manage.c
new file mode 100644
index 0000000..61d61ef
--- /dev/null
+++ b/src/openvpn/manage.c
@@ -0,0 +1,4023 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_MANAGEMENT
+
+#include "error.h"
+#include "fdmisc.h"
+#include "options.h"
+#include "sig.h"
+#include "event.h"
+#include "otime.h"
+#include "integer.h"
+#include "misc.h"
+#include "ssl.h"
+#include "common.h"
+#include "manage.h"
+
+#include "memdbg.h"
+
+#ifdef ENABLE_PKCS11
+#include "pkcs11.h"
+#endif
+
+#define MANAGEMENT_ECHO_PULL_INFO 0
+
+#if MANAGEMENT_ECHO_PULL_INFO
+#define MANAGEMENT_ECHO_FLAGS LOG_PRINT_INTVAL
+#else
+#define MANAGEMENT_ECHO_FLAGS 0
+#endif
+
+/* tag for blank username/password */
+static const char blank_up[] = "[[BLANK]]";
+
+struct management *management; /* GLOBAL */
+
+/* static forward declarations */
+static void man_output_standalone(struct management *man, volatile int *signal_received);
+
+static void man_reset_client_socket(struct management *man, const bool exiting);
+
+static void
+man_help(void)
+{
+    msg(M_CLIENT, "Management Interface for %s", title_string);
+    msg(M_CLIENT, "Commands:");
+    msg(M_CLIENT, "auth-retry t           : Auth failure retry mode (none,interact,nointeract).");
+    msg(M_CLIENT, "bytecount n            : Show bytes in/out, update every n secs (0=off).");
+    msg(M_CLIENT, "echo [on|off] [N|all]  : Like log, but only show messages in echo buffer.");
+    msg(M_CLIENT, "exit|quit              : Close management session.");
+    msg(M_CLIENT, "forget-passwords       : Forget passwords entered so far.");
+    msg(M_CLIENT, "help                   : Print this message.");
+    msg(M_CLIENT, "hold [on|off|release]  : Set/show hold flag to on/off state, or");
+    msg(M_CLIENT, "                         release current hold and start tunnel.");
+    msg(M_CLIENT, "kill cn                : Kill the client instance(s) having common name cn.");
+    msg(M_CLIENT, "kill IP:port           : Kill the client instance connecting from IP:port.");
+    msg(M_CLIENT, "load-stats             : Show global server load stats.");
+    msg(M_CLIENT, "log [on|off] [N|all]   : Turn on/off realtime log display");
+    msg(M_CLIENT, "                         + show last N lines or 'all' for entire history.");
+    msg(M_CLIENT, "mute [n]               : Set log mute level to n, or show level if n is absent.");
+    msg(M_CLIENT, "needok type action     : Enter confirmation for NEED-OK request of 'type',");
+    msg(M_CLIENT, "                         where action = 'ok' or 'cancel'.");
+    msg(M_CLIENT, "needstr type action    : Enter confirmation for NEED-STR request of 'type',");
+    msg(M_CLIENT, "                         where action is reply string.");
+    msg(M_CLIENT, "net                    : (Windows only) Show network info and routing table.");
+    msg(M_CLIENT, "password type p        : Enter password p for a queried OpenVPN password.");
+    msg(M_CLIENT, "remote type [host port] : Override remote directive, type=ACCEPT|MOD|SKIP.");
+    msg(M_CLIENT, "proxy type [host port flags] : Enter dynamic proxy server info.");
+    msg(M_CLIENT, "pid                    : Show process ID of the current OpenVPN process.");
+#ifdef ENABLE_PKCS11
+    msg(M_CLIENT, "pkcs11-id-count        : Get number of available PKCS#11 identities.");
+    msg(M_CLIENT, "pkcs11-id-get index    : Get PKCS#11 identity at index.");
+#endif
+#ifdef MANAGEMENT_DEF_AUTH
+    msg(M_CLIENT, "client-auth CID KID    : Authenticate client-id/key-id CID/KID (MULTILINE)");
+    msg(M_CLIENT, "client-auth-nt CID KID : Authenticate client-id/key-id CID/KID");
+    msg(M_CLIENT, "client-deny CID KID R [CR] : Deny auth client-id/key-id CID/KID with log reason");
+    msg(M_CLIENT, "                             text R and optional client reason text CR");
+    msg(M_CLIENT, "client-kill CID [M]    : Kill client instance CID with message M (def=RESTART)");
+    msg(M_CLIENT, "env-filter [level]     : Set env-var filter level");
+#ifdef MANAGEMENT_PF
+    msg(M_CLIENT, "client-pf CID          : Define packet filter for client CID (MULTILINE)");
+#endif
+#endif
+#ifdef MANAGMENT_EXTERNAL_KEY
+    msg(M_CLIENT, "rsa-sig                : Enter an RSA signature in response to >RSA_SIGN challenge");
+    msg(M_CLIENT, "                         Enter signature base64 on subsequent lines followed by END");
+    msg(M_CLIENT, "certificate            : Enter a client certificate in response to >NEED-CERT challenge");
+    msg(M_CLIENT, "                         Enter certificate base64 on subsequent lines followed by END");
+#endif
+    msg(M_CLIENT, "signal s               : Send signal s to daemon,");
+    msg(M_CLIENT, "                         s = SIGHUP|SIGTERM|SIGUSR1|SIGUSR2.");
+    msg(M_CLIENT, "state [on|off] [N|all] : Like log, but show state history.");
+    msg(M_CLIENT, "status [n]             : Show current daemon status info using format #n.");
+    msg(M_CLIENT, "test n                 : Produce n lines of output for testing/debugging.");
+    msg(M_CLIENT, "username type u        : Enter username u for a queried OpenVPN username.");
+    msg(M_CLIENT, "verb [n]               : Set log verbosity level to n, or show if n is absent.");
+    msg(M_CLIENT, "version                : Show current version number.");
+    msg(M_CLIENT, "END");
+}
+
+static const char *
+man_state_name(const int state)
+{
+    switch (state)
+    {
+        case OPENVPN_STATE_INITIAL:
+            return "INITIAL";
+
+        case OPENVPN_STATE_CONNECTING:
+            return "CONNECTING";
+
+        case OPENVPN_STATE_WAIT:
+            return "WAIT";
+
+        case OPENVPN_STATE_AUTH:
+            return "AUTH";
+
+        case OPENVPN_STATE_GET_CONFIG:
+            return "GET_CONFIG";
+
+        case OPENVPN_STATE_ASSIGN_IP:
+            return "ASSIGN_IP";
+
+        case OPENVPN_STATE_ADD_ROUTES:
+            return "ADD_ROUTES";
+
+        case OPENVPN_STATE_CONNECTED:
+            return "CONNECTED";
+
+        case OPENVPN_STATE_RECONNECTING:
+            return "RECONNECTING";
+
+        case OPENVPN_STATE_EXITING:
+            return "EXITING";
+
+        case OPENVPN_STATE_RESOLVE:
+            return "RESOLVE";
+
+        case OPENVPN_STATE_TCP_CONNECT:
+            return "TCP_CONNECT";
+
+        default:
+            return "?";
+    }
+}
+
+static void
+man_welcome(struct management *man)
+{
+    msg(M_CLIENT, ">INFO:OpenVPN Management Interface Version %d -- type 'help' for more info",
+        MANAGEMENT_VERSION);
+    if (man->persist.special_state_msg)
+    {
+        msg(M_CLIENT, "%s", man->persist.special_state_msg);
+    }
+}
+
+static inline bool
+man_password_needed(struct management *man)
+{
+    return man->settings.up.defined && !man->connection.password_verified;
+}
+
+static void
+man_check_password(struct management *man, const char *line)
+{
+    if (man_password_needed(man))
+    {
+        if (streq(line, man->settings.up.password))
+        {
+            man->connection.password_verified = true;
+            msg(M_CLIENT, "SUCCESS: password is correct");
+            man_welcome(man);
+        }
+        else
+        {
+            man->connection.password_verified = false;
+            msg(M_CLIENT, "ERROR: bad password");
+            if (++man->connection.password_tries >= MANAGEMENT_N_PASSWORD_RETRIES)
+            {
+                msg(M_WARN, "MAN: client connection rejected after %d failed password attempts",
+                    MANAGEMENT_N_PASSWORD_RETRIES);
+                man->connection.halt = true;
+            }
+        }
+    }
+}
+
+static void
+man_update_io_state(struct management *man)
+{
+    if (socket_defined(man->connection.sd_cli))
+    {
+        if (buffer_list_defined(man->connection.out))
+        {
+            man->connection.state = MS_CC_WAIT_WRITE;
+        }
+        else
+        {
+            man->connection.state = MS_CC_WAIT_READ;
+        }
+    }
+}
+
+static void
+man_output_list_push_finalize(struct management *man)
+{
+    if (management_connected(man))
+    {
+        man_update_io_state(man);
+        if (!man->persist.standalone_disabled)
+        {
+            volatile int signal_received = 0;
+            man_output_standalone(man, &signal_received);
+        }
+    }
+}
+
+static void
+man_output_list_push_str(struct management *man, const char *str)
+{
+    if (management_connected(man) && str)
+    {
+        buffer_list_push(man->connection.out, str);
+    }
+}
+
+static void
+man_output_list_push(struct management *man, const char *str)
+{
+    man_output_list_push_str(man, str);
+    man_output_list_push_finalize(man);
+}
+
+static void
+man_prompt(struct management *man)
+{
+    if (man_password_needed(man))
+    {
+        man_output_list_push(man, "ENTER PASSWORD:");
+    }
+#if 0 /* should we use prompt? */
+    else
+    {
+        man_output_list_push(man, ">");
+    }
+#endif
+}
+
+static void
+man_delete_unix_socket(struct management *man)
+{
+#if UNIX_SOCK_SUPPORT
+    if ((man->settings.flags & (MF_UNIX_SOCK|MF_CONNECT_AS_CLIENT)) == MF_UNIX_SOCK)
+    {
+        socket_delete_unix(&man->settings.local_unix);
+    }
+#endif
+}
+
+static void
+man_close_socket(struct management *man, const socket_descriptor_t sd)
+{
+#ifndef _WIN32
+    /*
+     * Windows doesn't need this because the ne32 event is permanently
+     * enabled at struct management scope.
+     */
+    if (man->persist.callback.delete_event)
+    {
+        (*man->persist.callback.delete_event)(man->persist.callback.arg, sd);
+    }
+#endif
+    openvpn_close_socket(sd);
+}
+
+static void
+virtual_output_callback_func(void *arg, const unsigned int flags, const char *str)
+{
+    struct management *man = (struct management *) arg;
+    static int recursive_level = 0; /* GLOBAL */
+
+#define AF_DID_PUSH  (1<<0)
+#define AF_DID_RESET (1<<1)
+
+    if (!recursive_level) /* don't allow recursion */
+    {
+        struct gc_arena gc = gc_new();
+        struct log_entry e;
+        const char *out = NULL;
+        unsigned int action_flags = 0;
+
+        ++recursive_level;
+
+        CLEAR(e);
+        update_time();
+        e.timestamp = now;
+        e.u.msg_flags = flags;
+        e.string = str;
+
+        if (flags & M_FATAL)
+        {
+            man->persist.standalone_disabled = false;
+        }
+
+        if (flags != M_CLIENT)
+        {
+            log_history_add(man->persist.log, &e);
+        }
+
+        if (!man_password_needed(man))
+        {
+            if (flags == M_CLIENT)
+            {
+                out = log_entry_print(&e, LOG_PRINT_CRLF, &gc);
+            }
+            else if (man->connection.log_realtime)
+            {
+                out = log_entry_print(&e, LOG_PRINT_INT_DATE
+                                      |   LOG_PRINT_MSG_FLAGS
+                                      |   LOG_PRINT_LOG_PREFIX
+                                      |   LOG_PRINT_CRLF, &gc);
+            }
+            if (out)
+            {
+                man_output_list_push_str(man, out);
+                action_flags |= AF_DID_PUSH;
+            }
+            if (flags & M_FATAL)
+            {
+                out = log_entry_print(&e, LOG_FATAL_NOTIFY|LOG_PRINT_CRLF, &gc);
+                if (out)
+                {
+                    man_output_list_push_str(man, out);
+                    action_flags |= (AF_DID_PUSH|AF_DID_RESET);
+                }
+            }
+        }
+
+        gc_free(&gc);
+
+        if (action_flags & AF_DID_PUSH)
+        {
+            man_output_list_push_finalize(man);
+        }
+        if (action_flags & AF_DID_RESET)
+        {
+            man_reset_client_socket(man, true);
+        }
+
+        --recursive_level;
+    }
+}
+
+/*
+ * Given a signal, return the signal with possible remapping applied,
+ * or -1 if the signal should be ignored.
+ */
+static int
+man_mod_signal(const struct management *man, const int signum)
+{
+    const unsigned int flags = man->settings.mansig;
+    int s = signum;
+    if (s == SIGUSR1)
+    {
+        if (flags & MANSIG_MAP_USR1_TO_HUP)
+        {
+            s = SIGHUP;
+        }
+        if (flags & MANSIG_MAP_USR1_TO_TERM)
+        {
+            s = SIGTERM;
+        }
+    }
+    if (flags & MANSIG_IGNORE_USR1_HUP)
+    {
+        if (s == SIGHUP || s == SIGUSR1)
+        {
+            s = -1;
+        }
+    }
+    return s;
+}
+
+static void
+man_signal(struct management *man, const char *name)
+{
+    const int sig = parse_signal(name);
+    if (sig >= 0)
+    {
+        const int sig_mod = man_mod_signal(man, sig);
+        if (sig_mod >= 0)
+        {
+            throw_signal(sig_mod);
+            msg(M_CLIENT, "SUCCESS: signal %s thrown", signal_name(sig_mod, true));
+        }
+        else
+        {
+            if (man->persist.special_state_msg)
+            {
+                msg(M_CLIENT, "%s", man->persist.special_state_msg);
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: signal '%s' is currently ignored", name);
+            }
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: signal '%s' is not a known signal type", name);
+    }
+}
+
+static void
+man_status(struct management *man, const int version, struct status_output *so)
+{
+    if (man->persist.callback.status)
+    {
+        (*man->persist.callback.status)(man->persist.callback.arg, version, so);
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The 'status' command is not supported by the current daemon mode");
+    }
+}
+
+static void
+man_bytecount(struct management *man, const int update_seconds)
+{
+    if (update_seconds >= 0)
+    {
+        man->connection.bytecount_update_seconds = update_seconds;
+    }
+    else
+    {
+        man->connection.bytecount_update_seconds = 0;
+    }
+    msg(M_CLIENT, "SUCCESS: bytecount interval changed");
+}
+
+void
+man_bytecount_output_client(struct management *man)
+{
+    char in[32];
+    char out[32];
+    /* do in a roundabout way to work around possible mingw or mingw-glibc bug */
+    openvpn_snprintf(in, sizeof(in), counter_format, man->persist.bytes_in);
+    openvpn_snprintf(out, sizeof(out), counter_format, man->persist.bytes_out);
+    msg(M_CLIENT, ">BYTECOUNT:%s,%s", in, out);
+    man->connection.bytecount_last_update = now;
+}
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+void
+man_bytecount_output_server(struct management *man,
+                            const counter_type *bytes_in_total,
+                            const counter_type *bytes_out_total,
+                            struct man_def_auth_context *mdac)
+{
+    char in[32];
+    char out[32];
+    /* do in a roundabout way to work around possible mingw or mingw-glibc bug */
+    openvpn_snprintf(in, sizeof(in), counter_format, *bytes_in_total);
+    openvpn_snprintf(out, sizeof(out), counter_format, *bytes_out_total);
+    msg(M_CLIENT, ">BYTECOUNT_CLI:%lu,%s,%s", mdac->cid, in, out);
+    mdac->bytecount_last_update = now;
+}
+
+#endif
+
+static void
+man_kill(struct management *man, const char *victim)
+{
+    struct gc_arena gc = gc_new();
+
+    if (man->persist.callback.kill_by_cn && man->persist.callback.kill_by_addr)
+    {
+        struct buffer buf;
+        char p1[128];
+        char p2[128];
+        int n_killed;
+
+        buf_set_read(&buf, (uint8_t *) victim, strlen(victim) + 1);
+        buf_parse(&buf, ':', p1, sizeof(p1));
+        buf_parse(&buf, ':', p2, sizeof(p2));
+
+        if (strlen(p1) && strlen(p2))
+        {
+            /* IP:port specified */
+            bool status;
+            const in_addr_t addr = getaddr(GETADDR_HOST_ORDER|GETADDR_MSG_VIRT_OUT, p1, 0, &status, NULL);
+            if (status)
+            {
+                const int port = atoi(p2);
+                if (port > 0 && port < 65536)
+                {
+                    n_killed = (*man->persist.callback.kill_by_addr)(man->persist.callback.arg, addr, port);
+                    if (n_killed > 0)
+                    {
+                        msg(M_CLIENT, "SUCCESS: %d client(s) at address %s:%d killed",
+                            n_killed,
+                            print_in_addr_t(addr, 0, &gc),
+                            port);
+                    }
+                    else
+                    {
+                        msg(M_CLIENT, "ERROR: client at address %s:%d not found",
+                            print_in_addr_t(addr, 0, &gc),
+                            port);
+                    }
+                }
+                else
+                {
+                    msg(M_CLIENT, "ERROR: port number is out of range: %s", p2);
+                }
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: error parsing IP address: %s", p1);
+            }
+        }
+        else if (strlen(p1))
+        {
+            /* common name specified */
+            n_killed = (*man->persist.callback.kill_by_cn)(man->persist.callback.arg, p1);
+            if (n_killed > 0)
+            {
+                msg(M_CLIENT, "SUCCESS: common name '%s' found, %d client(s) killed", p1, n_killed);
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: common name '%s' not found", p1);
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: kill parse");
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The 'kill' command is not supported by the current daemon mode");
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * General-purpose history command handler
+ * for the log and echo commands.
+ */
+static void
+man_history(struct management *man,
+            const char *parm,
+            const char *type,
+            struct log_history *log,
+            bool *realtime,
+            const unsigned int lep_flags)
+{
+    struct gc_arena gc = gc_new();
+    int n = 0;
+
+    if (streq(parm, "on"))
+    {
+        *realtime = true;
+        msg(M_CLIENT, "SUCCESS: real-time %s notification set to ON", type);
+    }
+    else if (streq(parm, "off"))
+    {
+        *realtime = false;
+        msg(M_CLIENT, "SUCCESS: real-time %s notification set to OFF", type);
+    }
+    else if (streq(parm, "all") || (n = atoi(parm)) > 0)
+    {
+        const int size = log_history_size(log);
+        const int start = (n ? n : size) - 1;
+        int i;
+
+        for (i = start; i >= 0; --i)
+        {
+            const struct log_entry *e = log_history_ref(log, i);
+            if (e)
+            {
+                const char *out = log_entry_print(e, lep_flags, &gc);
+                virtual_output_callback_func(man, M_CLIENT, out);
+            }
+        }
+        msg(M_CLIENT, "END");
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: %s parameter must be 'on' or 'off' or some number n or 'all'", type);
+    }
+
+    gc_free(&gc);
+}
+
+static void
+man_log(struct management *man, const char *parm)
+{
+    man_history(man,
+                parm,
+                "log",
+                man->persist.log,
+                &man->connection.log_realtime,
+                LOG_PRINT_INT_DATE|LOG_PRINT_MSG_FLAGS);
+}
+
+static void
+man_echo(struct management *man, const char *parm)
+{
+    man_history(man,
+                parm,
+                "echo",
+                man->persist.echo,
+                &man->connection.echo_realtime,
+                LOG_PRINT_INT_DATE|MANAGEMENT_ECHO_FLAGS);
+}
+
+static void
+man_state(struct management *man, const char *parm)
+{
+    man_history(man,
+                parm,
+                "state",
+                man->persist.state,
+                &man->connection.state_realtime,
+                LOG_PRINT_INT_DATE|LOG_PRINT_STATE
+                |LOG_PRINT_LOCAL_IP|LOG_PRINT_REMOTE_IP);
+}
+
+static void
+man_up_finalize(struct management *man)
+{
+    switch (man->connection.up_query_mode)
+    {
+        case UP_QUERY_USER_PASS:
+            if (!strlen(man->connection.up_query.username))
+            {
+                break;
+            }
+
+        /* fall through */
+        case UP_QUERY_PASS:
+        case UP_QUERY_NEED_OK:
+        case UP_QUERY_NEED_STR:
+            if (strlen(man->connection.up_query.password))
+            {
+                man->connection.up_query.defined = true;
+            }
+            break;
+
+        case UP_QUERY_DISABLED:
+            man->connection.up_query.defined = false;
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+static void
+man_query_user_pass(struct management *man,
+                    const char *type,
+                    const char *string,
+                    const bool needed,
+                    const char *prompt,
+                    char *dest,
+                    int len)
+{
+    if (needed)
+    {
+        ASSERT(man->connection.up_query_type);
+        if (streq(man->connection.up_query_type, type))
+        {
+            strncpynt(dest, string, len);
+            man_up_finalize(man);
+            msg(M_CLIENT, "SUCCESS: '%s' %s entered, but not yet verified",
+                type,
+                prompt);
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: %s of type '%s' entered, but we need one of type '%s'",
+                prompt,
+                type,
+                man->connection.up_query_type);
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: no %s is currently needed at this time", prompt);
+    }
+}
+
+static void
+man_query_username(struct management *man, const char *type, const char *string)
+{
+    const bool needed = ((man->connection.up_query_mode == UP_QUERY_USER_PASS
+                          ) && man->connection.up_query_type);
+    man_query_user_pass(man, type, string, needed, "username", man->connection.up_query.username, USER_PASS_LEN);
+}
+
+static void
+man_query_password(struct management *man, const char *type, const char *string)
+{
+    const bool needed = ((man->connection.up_query_mode == UP_QUERY_PASS
+                          || man->connection.up_query_mode == UP_QUERY_USER_PASS
+                          ) && man->connection.up_query_type);
+    if (!string[0]) /* allow blank passwords to be passed through using the blank_up tag */
+    {
+        string = blank_up;
+    }
+    man_query_user_pass(man, type, string, needed, "password", man->connection.up_query.password, USER_PASS_LEN);
+}
+
+static void
+man_query_need_ok(struct management *man, const char *type, const char *action)
+{
+    const bool needed = ((man->connection.up_query_mode == UP_QUERY_NEED_OK) && man->connection.up_query_type);
+    man_query_user_pass(man, type, action, needed, "needok-confirmation", man->connection.up_query.password, USER_PASS_LEN);
+}
+
+static void
+man_query_need_str(struct management *man, const char *type, const char *action)
+{
+    const bool needed = ((man->connection.up_query_mode == UP_QUERY_NEED_STR) && man->connection.up_query_type);
+    man_query_user_pass(man, type, action, needed, "needstr-string", man->connection.up_query.password, USER_PASS_LEN);
+}
+
+static void
+man_forget_passwords(struct management *man)
+{
+#ifdef ENABLE_CRYPTO
+    ssl_purge_auth(false);
+    msg(M_CLIENT, "SUCCESS: Passwords were forgotten");
+#endif
+}
+
+static void
+man_net(struct management *man)
+{
+    if (man->persist.callback.show_net)
+    {
+        (*man->persist.callback.show_net)(man->persist.callback.arg, M_CLIENT);
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The 'net' command is not supported by the current daemon mode");
+    }
+}
+
+#ifdef ENABLE_PKCS11
+
+static void
+man_pkcs11_id_count(struct management *man)
+{
+    msg(M_CLIENT, ">PKCS11ID-COUNT:%d", pkcs11_management_id_count());
+}
+
+static void
+man_pkcs11_id_get(struct management *man, const int index)
+{
+    char *id = NULL;
+    char *base64 = NULL;
+
+    if (pkcs11_management_id_get(index, &id, &base64))
+    {
+        msg(M_CLIENT, ">PKCS11ID-ENTRY:'%d', ID:'%s', BLOB:'%s'", index, id, base64);
+    }
+    else
+    {
+        msg(M_CLIENT, ">PKCS11ID-ENTRY:'%d'", index);
+    }
+
+    if (id != NULL)
+    {
+        free(id);
+    }
+    if (base64 != NULL)
+    {
+        free(base64);
+    }
+}
+
+#endif /* ifdef ENABLE_PKCS11 */
+
+static void
+man_hold(struct management *man, const char *cmd)
+{
+    if (cmd)
+    {
+        if (streq(cmd, "on"))
+        {
+            man->settings.flags |= MF_HOLD;
+            msg(M_CLIENT, "SUCCESS: hold flag set to ON");
+        }
+        else if (streq(cmd, "off"))
+        {
+            man->settings.flags &= ~MF_HOLD;
+            msg(M_CLIENT, "SUCCESS: hold flag set to OFF");
+        }
+        else if (streq(cmd, "release"))
+        {
+            man->persist.hold_release = true;
+            msg(M_CLIENT, "SUCCESS: hold release succeeded");
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: bad hold command parameter");
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "SUCCESS: hold=%d", BOOL_CAST(man->settings.flags & MF_HOLD));
+    }
+}
+
+#ifdef MANAGEMENT_IN_EXTRA
+
+#define IER_RESET      0
+#define IER_NEW        1
+
+static void
+in_extra_reset(struct man_connection *mc, const int mode)
+{
+    if (mc)
+    {
+        if (mode != IER_NEW)
+        {
+            mc->in_extra_cmd = IEC_UNDEF;
+#ifdef MANAGEMENT_DEF_AUTH
+            mc->in_extra_cid = 0;
+            mc->in_extra_kid = 0;
+#endif
+        }
+        if (mc->in_extra)
+        {
+            buffer_list_free(mc->in_extra);
+            mc->in_extra = NULL;
+        }
+        if (mode == IER_NEW)
+        {
+            mc->in_extra = buffer_list_new(0);
+        }
+    }
+}
+
+static void
+in_extra_dispatch(struct management *man)
+{
+    switch (man->connection.in_extra_cmd)
+    {
+#ifdef MANAGEMENT_DEF_AUTH
+        case IEC_CLIENT_AUTH:
+            if (man->persist.callback.client_auth)
+            {
+                const bool status = (*man->persist.callback.client_auth)
+                                        (man->persist.callback.arg,
+                                        man->connection.in_extra_cid,
+                                        man->connection.in_extra_kid,
+                                        true,
+                                        NULL,
+                                        NULL,
+                                        man->connection.in_extra);
+                man->connection.in_extra = NULL;
+                if (status)
+                {
+                    msg(M_CLIENT, "SUCCESS: client-auth command succeeded");
+                }
+                else
+                {
+                    msg(M_CLIENT, "ERROR: client-auth command failed");
+                }
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: The client-auth command is not supported by the current daemon mode");
+            }
+            break;
+
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+#ifdef MANAGEMENT_PF
+        case IEC_CLIENT_PF:
+            if (man->persist.callback.client_pf)
+            {
+                const bool status = (*man->persist.callback.client_pf)
+                                        (man->persist.callback.arg,
+                                        man->connection.in_extra_cid,
+                                        man->connection.in_extra);
+                man->connection.in_extra = NULL;
+                if (status)
+                {
+                    msg(M_CLIENT, "SUCCESS: client-pf command succeeded");
+                }
+                else
+                {
+                    msg(M_CLIENT, "ERROR: client-pf command failed");
+                }
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: The client-pf command is not supported by the current daemon mode");
+            }
+            break;
+
+#endif /* ifdef MANAGEMENT_PF */
+#ifdef MANAGMENT_EXTERNAL_KEY
+        case IEC_RSA_SIGN:
+            man->connection.ext_key_state = EKS_READY;
+            buffer_list_free(man->connection.ext_key_input);
+            man->connection.ext_key_input = man->connection.in_extra;
+            man->connection.in_extra = NULL;
+            return;
+
+        case IEC_CERTIFICATE:
+            man->connection.ext_cert_state = EKS_READY;
+            buffer_list_free(man->connection.ext_cert_input);
+            man->connection.ext_cert_input = man->connection.in_extra;
+            man->connection.in_extra = NULL;
+            return;
+#endif
+    }
+    in_extra_reset(&man->connection, IER_RESET);
+}
+
+#endif /* MANAGEMENT_IN_EXTRA */
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+static bool
+parse_cid(const char *str, unsigned long *cid)
+{
+    if (sscanf(str, "%lu", cid) == 1)
+    {
+        return true;
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: cannot parse CID");
+        return false;
+    }
+}
+
+static bool
+parse_kid(const char *str, unsigned int *kid)
+{
+    if (sscanf(str, "%u", kid) == 1)
+    {
+        return true;
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: cannot parse KID");
+        return false;
+    }
+}
+
+static void
+man_client_auth(struct management *man, const char *cid_str, const char *kid_str, const bool extra)
+{
+    struct man_connection *mc = &man->connection;
+    mc->in_extra_cid = 0;
+    mc->in_extra_kid = 0;
+    if (parse_cid(cid_str, &mc->in_extra_cid)
+        && parse_kid(kid_str, &mc->in_extra_kid))
+    {
+        mc->in_extra_cmd = IEC_CLIENT_AUTH;
+        in_extra_reset(mc, IER_NEW);
+        if (!extra)
+        {
+            in_extra_dispatch(man);
+        }
+    }
+}
+
+static void
+man_client_deny(struct management *man, const char *cid_str, const char *kid_str, const char *reason, const char *client_reason)
+{
+    unsigned long cid = 0;
+    unsigned int kid = 0;
+    if (parse_cid(cid_str, &cid) && parse_kid(kid_str, &kid))
+    {
+        if (man->persist.callback.client_auth)
+        {
+            const bool status = (*man->persist.callback.client_auth)
+                                    (man->persist.callback.arg,
+                                    cid,
+                                    kid,
+                                    false,
+                                    reason,
+                                    client_reason,
+                                    NULL);
+            if (status)
+            {
+                msg(M_CLIENT, "SUCCESS: client-deny command succeeded");
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: client-deny command failed");
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: The client-deny command is not supported by the current daemon mode");
+        }
+    }
+}
+
+static void
+man_client_kill(struct management *man, const char *cid_str, const char *kill_msg)
+{
+    unsigned long cid = 0;
+    if (parse_cid(cid_str, &cid))
+    {
+        if (man->persist.callback.kill_by_cid)
+        {
+            const bool status = (*man->persist.callback.kill_by_cid)(man->persist.callback.arg, cid, kill_msg);
+            if (status)
+            {
+                msg(M_CLIENT, "SUCCESS: client-kill command succeeded");
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: client-kill command failed");
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: The client-kill command is not supported by the current daemon mode");
+        }
+    }
+}
+
+static void
+man_client_n_clients(struct management *man)
+{
+    if (man->persist.callback.n_clients)
+    {
+        const int nclients = (*man->persist.callback.n_clients)(man->persist.callback.arg);
+        msg(M_CLIENT, "SUCCESS: nclients=%d", nclients);
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The nclients command is not supported by the current daemon mode");
+    }
+}
+
+static void
+man_env_filter(struct management *man, const int level)
+{
+    man->connection.env_filter_level = level;
+    msg(M_CLIENT, "SUCCESS: env_filter_level=%d", level);
+}
+
+#ifdef MANAGEMENT_PF
+
+static void
+man_client_pf(struct management *man, const char *cid_str)
+{
+    struct man_connection *mc = &man->connection;
+    mc->in_extra_cid = 0;
+    mc->in_extra_kid = 0;
+    if (parse_cid(cid_str, &mc->in_extra_cid))
+    {
+        mc->in_extra_cmd = IEC_CLIENT_PF;
+        in_extra_reset(mc, IER_NEW);
+    }
+}
+
+#endif /* MANAGEMENT_PF */
+#endif /* MANAGEMENT_DEF_AUTH */
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+static void
+man_rsa_sig(struct management *man)
+{
+    struct man_connection *mc = &man->connection;
+    if (mc->ext_key_state == EKS_SOLICIT)
+    {
+        mc->ext_key_state = EKS_INPUT;
+        mc->in_extra_cmd = IEC_RSA_SIGN;
+        in_extra_reset(mc, IER_NEW);
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The rsa-sig command is not currently available");
+    }
+}
+
+static void
+man_certificate(struct management *man)
+{
+    struct man_connection *mc = &man->connection;
+    if (mc->ext_cert_state == EKS_SOLICIT)
+    {
+        mc->ext_cert_state = EKS_INPUT;
+        mc->in_extra_cmd = IEC_CERTIFICATE;
+        in_extra_reset(mc, IER_NEW);
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The certificate command is not currently available");
+    }
+}
+
+#endif /* ifdef MANAGMENT_EXTERNAL_KEY */
+
+static void
+man_load_stats(struct management *man)
+{
+    extern counter_type link_read_bytes_global;
+    extern counter_type link_write_bytes_global;
+    int nclients = 0;
+
+    if (man->persist.callback.n_clients)
+    {
+        nclients = (*man->persist.callback.n_clients)(man->persist.callback.arg);
+    }
+    msg(M_CLIENT, "SUCCESS: nclients=%d,bytesin=" counter_format ",bytesout=" counter_format,
+        nclients,
+        link_read_bytes_global,
+        link_write_bytes_global);
+}
+
+#define MN_AT_LEAST (1<<0)
+
+static bool
+man_need(struct management *man, const char **p, const int n, unsigned int flags)
+{
+    int i;
+    ASSERT(p[0]);
+    for (i = 1; i <= n; ++i)
+    {
+        if (!p[i])
+        {
+            msg(M_CLIENT, "ERROR: the '%s' command requires %s%d parameter%s",
+                p[0],
+                (flags & MN_AT_LEAST) ? "at least " : "",
+                n,
+                n > 1 ? "s" : "");
+            return false;
+        }
+    }
+    return true;
+}
+
+static void
+man_proxy(struct management *man, const char **p)
+{
+    if (man->persist.callback.proxy_cmd)
+    {
+        const bool status = (*man->persist.callback.proxy_cmd)(man->persist.callback.arg, p);
+        if (status)
+        {
+            msg(M_CLIENT, "SUCCESS: proxy command succeeded");
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: proxy command failed");
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The proxy command is not supported by the current daemon mode");
+    }
+}
+
+static void
+man_remote(struct management *man, const char **p)
+{
+    if (man->persist.callback.remote_cmd)
+    {
+        const bool status = (*man->persist.callback.remote_cmd)(man->persist.callback.arg, p);
+        if (status)
+        {
+            msg(M_CLIENT, "SUCCESS: remote command succeeded");
+        }
+        else
+        {
+            msg(M_CLIENT, "ERROR: remote command failed");
+        }
+    }
+    else
+    {
+        msg(M_CLIENT, "ERROR: The remote command is not supported by the current daemon mode");
+    }
+}
+
+#ifdef TARGET_ANDROID
+static void
+man_network_change(struct management *man, bool samenetwork)
+{
+    /* Called to signal the OpenVPN that the network configuration has changed and
+     * the client should either float or reconnect.
+     *
+     * The code is currently only used by ics-openvpn
+     */
+    if (man->persist.callback.network_change)
+    {
+        int fd = (*man->persist.callback.network_change)
+                     (man->persist.callback.arg, samenetwork);
+        man->connection.fdtosend = fd;
+        msg(M_CLIENT, "PROTECTFD: fd '%d' sent to be protected", fd);
+        if (fd == -2)
+        {
+            man_signal(man, "SIGUSR1");
+        }
+    }
+}
+#endif
+
+static void
+man_dispatch_command(struct management *man, struct status_output *so, const char **p, const int nparms)
+{
+    struct gc_arena gc = gc_new();
+
+    ASSERT(p[0]);
+    if (streq(p[0], "exit") || streq(p[0], "quit"))
+    {
+        man->connection.halt = true;
+        goto done;
+    }
+    else if (streq(p[0], "help"))
+    {
+        man_help();
+    }
+    else if (streq(p[0], "version"))
+    {
+        msg(M_CLIENT, "OpenVPN Version: %s", title_string);
+        msg(M_CLIENT, "Management Version: %d", MANAGEMENT_VERSION);
+        msg(M_CLIENT, "END");
+    }
+    else if (streq(p[0], "pid"))
+    {
+        msg(M_CLIENT, "SUCCESS: pid=%d", platform_getpid());
+    }
+#ifdef MANAGEMENT_DEF_AUTH
+    else if (streq(p[0], "nclients"))
+    {
+        man_client_n_clients(man);
+    }
+    else if (streq(p[0], "env-filter"))
+    {
+        int level = 0;
+        if (p[1])
+        {
+            level = atoi(p[1]);
+        }
+        man_env_filter(man, level);
+    }
+#endif
+    else if (streq(p[0], "signal"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            man_signal(man, p[1]);
+        }
+    }
+#ifdef TARGET_ANDROID
+    else if (streq(p[0], "network-change"))
+    {
+        bool samenetwork = false;
+        if (p[1] && streq(p[1], "samenetwork"))
+        {
+            samenetwork = true;
+        }
+
+        man_network_change(man, samenetwork);
+    }
+#endif
+    else if (streq(p[0], "load-stats"))
+    {
+        man_load_stats(man);
+    }
+    else if (streq(p[0], "status"))
+    {
+        int version = 0;
+        if (p[1])
+        {
+            version = atoi(p[1]);
+        }
+        man_status(man, version, so);
+    }
+    else if (streq(p[0], "kill"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            man_kill(man, p[1]);
+        }
+    }
+    else if (streq(p[0], "verb"))
+    {
+        if (p[1])
+        {
+            const int level = atoi(p[1]);
+            if (set_debug_level(level, 0))
+            {
+                msg(M_CLIENT, "SUCCESS: verb level changed");
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: verb level is out of range");
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "SUCCESS: verb=%d", get_debug_level());
+        }
+    }
+    else if (streq(p[0], "mute"))
+    {
+        if (p[1])
+        {
+            const int level = atoi(p[1]);
+            if (set_mute_cutoff(level))
+            {
+                msg(M_CLIENT, "SUCCESS: mute level changed");
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: mute level is out of range");
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "SUCCESS: mute=%d", get_mute_cutoff());
+        }
+    }
+    else if (streq(p[0], "auth-retry"))
+    {
+#if P2MP
+        if (p[1])
+        {
+            if (auth_retry_set(M_CLIENT, p[1]))
+            {
+                msg(M_CLIENT, "SUCCESS: auth-retry parameter changed");
+            }
+            else
+            {
+                msg(M_CLIENT, "ERROR: bad auth-retry parameter");
+            }
+        }
+        else
+        {
+            msg(M_CLIENT, "SUCCESS: auth-retry=%s", auth_retry_print());
+        }
+#else  /* if P2MP */
+        msg(M_CLIENT, "ERROR: auth-retry feature is unavailable");
+#endif
+    }
+    else if (streq(p[0], "state"))
+    {
+        if (!p[1])
+        {
+            man_state(man, "1");
+        }
+        else
+        {
+            if (p[1])
+            {
+                man_state(man, p[1]);
+            }
+            if (p[2])
+            {
+                man_state(man, p[2]);
+            }
+        }
+    }
+    else if (streq(p[0], "log"))
+    {
+        if (man_need(man, p, 1, MN_AT_LEAST))
+        {
+            if (p[1])
+            {
+                man_log(man, p[1]);
+            }
+            if (p[2])
+            {
+                man_log(man, p[2]);
+            }
+        }
+    }
+    else if (streq(p[0], "echo"))
+    {
+        if (man_need(man, p, 1, MN_AT_LEAST))
+        {
+            if (p[1])
+            {
+                man_echo(man, p[1]);
+            }
+            if (p[2])
+            {
+                man_echo(man, p[2]);
+            }
+        }
+    }
+    else if (streq(p[0], "username"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_query_username(man, p[1], p[2]);
+        }
+    }
+    else if (streq(p[0], "password"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_query_password(man, p[1], p[2]);
+        }
+    }
+    else if (streq(p[0], "forget-passwords"))
+    {
+        man_forget_passwords(man);
+    }
+    else if (streq(p[0], "needok"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_query_need_ok(man, p[1], p[2]);
+        }
+    }
+    else if (streq(p[0], "needstr"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_query_need_str(man, p[1], p[2]);
+        }
+    }
+    else if (streq(p[0], "net"))
+    {
+        man_net(man);
+    }
+    else if (streq(p[0], "hold"))
+    {
+        man_hold(man, p[1]);
+    }
+    else if (streq(p[0], "bytecount"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            man_bytecount(man, atoi(p[1]));
+        }
+    }
+#ifdef MANAGEMENT_DEF_AUTH
+    else if (streq(p[0], "client-kill"))
+    {
+        if (man_need(man, p, 1, MN_AT_LEAST))
+        {
+            man_client_kill(man, p[1], p[2]);
+        }
+    }
+    else if (streq(p[0], "client-deny"))
+    {
+        if (man_need(man, p, 3, MN_AT_LEAST))
+        {
+            man_client_deny(man, p[1], p[2], p[3], p[4]);
+        }
+    }
+    else if (streq(p[0], "client-auth-nt"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_client_auth(man, p[1], p[2], false);
+        }
+    }
+    else if (streq(p[0], "client-auth"))
+    {
+        if (man_need(man, p, 2, 0))
+        {
+            man_client_auth(man, p[1], p[2], true);
+        }
+    }
+#ifdef MANAGEMENT_PF
+    else if (streq(p[0], "client-pf"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            man_client_pf(man, p[1]);
+        }
+    }
+#endif
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+#ifdef MANAGMENT_EXTERNAL_KEY
+    else if (streq(p[0], "rsa-sig"))
+    {
+        man_rsa_sig(man);
+    }
+    else if (streq(p[0], "certificate"))
+    {
+        man_certificate(man);
+    }
+#endif
+#ifdef ENABLE_PKCS11
+    else if (streq(p[0], "pkcs11-id-count"))
+    {
+        man_pkcs11_id_count(man);
+    }
+    else if (streq(p[0], "pkcs11-id-get"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            man_pkcs11_id_get(man, atoi(p[1]));
+        }
+    }
+#endif
+    else if (streq(p[0], "proxy"))
+    {
+        if (man_need(man, p, 1, MN_AT_LEAST))
+        {
+            man_proxy(man, p);
+        }
+    }
+    else if (streq(p[0], "remote"))
+    {
+        if (man_need(man, p, 1, MN_AT_LEAST))
+        {
+            man_remote(man, p);
+        }
+    }
+#if 1
+    else if (streq(p[0], "test"))
+    {
+        if (man_need(man, p, 1, 0))
+        {
+            int i;
+            const int n = atoi(p[1]);
+            for (i = 0; i < n; ++i)
+            {
+                msg(M_CLIENT, "[%d] The purpose of this command is to generate large amounts of output.", i);
+            }
+        }
+    }
+#endif
+    else
+    {
+        msg(M_CLIENT, "ERROR: unknown command, enter 'help' for more options");
+    }
+
+done:
+    gc_free(&gc);
+}
+
+#ifdef _WIN32
+
+static void
+man_start_ne32(struct management *man)
+{
+    switch (man->connection.state)
+    {
+        case MS_LISTEN:
+            net_event_win32_start(&man->connection.ne32, FD_ACCEPT, man->connection.sd_top);
+            break;
+
+        case MS_CC_WAIT_READ:
+        case MS_CC_WAIT_WRITE:
+            net_event_win32_start(&man->connection.ne32, FD_READ|FD_WRITE|FD_CLOSE, man->connection.sd_cli);
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+static void
+man_stop_ne32(struct management *man)
+{
+    net_event_win32_stop(&man->connection.ne32);
+}
+
+#endif /* ifdef _WIN32 */
+
+static void
+man_record_peer_info(struct management *man)
+{
+    struct gc_arena gc = gc_new();
+    if (man->settings.write_peer_info_file)
+    {
+        bool success = false;
+#ifdef HAVE_GETSOCKNAME
+        if (socket_defined(man->connection.sd_cli))
+        {
+            struct sockaddr_in addr;
+            socklen_t addrlen = sizeof(addr);
+            int status;
+
+            CLEAR(addr);
+            status = getsockname(man->connection.sd_cli, (struct sockaddr *)&addr, &addrlen);
+            if (!status && addrlen == sizeof(addr))
+            {
+                const in_addr_t a = ntohl(addr.sin_addr.s_addr);
+                const int p = ntohs(addr.sin_port);
+                FILE *fp = platform_fopen(man->settings.write_peer_info_file, "w");
+                if (fp)
+                {
+                    fprintf(fp, "%s\n%d\n", print_in_addr_t(a, 0, &gc), p);
+                    if (!fclose(fp))
+                    {
+                        success = true;
+                    }
+                }
+            }
+        }
+#endif /* ifdef HAVE_GETSOCKNAME */
+        if (!success)
+        {
+            msg(D_MANAGEMENT, "MANAGEMENT: failed to write peer info to file %s",
+                man->settings.write_peer_info_file);
+            throw_signal_soft(SIGTERM, "management-connect-failed");
+        }
+    }
+    gc_free(&gc);
+}
+
+static void
+man_connection_settings_reset(struct management *man)
+{
+    man->connection.state_realtime = false;
+    man->connection.log_realtime = false;
+    man->connection.echo_realtime = false;
+    man->connection.bytecount_update_seconds = 0;
+    man->connection.password_verified = false;
+    man->connection.password_tries = 0;
+    man->connection.halt = false;
+    man->connection.state = MS_CC_WAIT_WRITE;
+}
+
+static void
+man_new_connection_post(struct management *man, const char *description)
+{
+    struct gc_arena gc = gc_new();
+
+    set_nonblock(man->connection.sd_cli);
+
+    man_connection_settings_reset(man);
+
+#ifdef _WIN32
+    man_start_ne32(man);
+#endif
+
+#if UNIX_SOCK_SUPPORT
+    if (man->settings.flags & MF_UNIX_SOCK)
+    {
+        msg(D_MANAGEMENT, "MANAGEMENT: %s %s",
+            description,
+            sockaddr_unix_name(&man->settings.local_unix, "NULL"));
+    }
+    else
+#endif
+    msg(D_MANAGEMENT, "MANAGEMENT: %s %s",
+        description,
+        print_sockaddr(man->settings.local->ai_addr, &gc));
+
+    buffer_list_reset(man->connection.out);
+
+    if (!man_password_needed(man))
+    {
+        man_welcome(man);
+    }
+    man_prompt(man);
+    man_update_io_state(man);
+
+    gc_free(&gc);
+}
+
+#if UNIX_SOCK_SUPPORT
+static bool
+man_verify_unix_peer_uid_gid(struct management *man, const socket_descriptor_t sd)
+{
+    if (socket_defined(sd) && (man->settings.client_uid != -1 || man->settings.client_gid != -1))
+    {
+        static const char err_prefix[] = "MANAGEMENT: unix domain socket client connection rejected --";
+        int uid, gid;
+        if (unix_socket_get_peer_uid_gid(man->connection.sd_cli, &uid, &gid))
+        {
+            if (man->settings.client_uid != -1 && man->settings.client_uid != uid)
+            {
+                msg(D_MANAGEMENT, "%s UID of socket peer (%d) doesn't match required value (%d) as given by --management-client-user",
+                    err_prefix, uid, man->settings.client_uid);
+                return false;
+            }
+            if (man->settings.client_gid != -1 && man->settings.client_gid != gid)
+            {
+                msg(D_MANAGEMENT, "%s GID of socket peer (%d) doesn't match required value (%d) as given by --management-client-group",
+                    err_prefix, gid, man->settings.client_gid);
+                return false;
+            }
+        }
+        else
+        {
+            msg(D_MANAGEMENT, "%s cannot get UID/GID of socket peer", err_prefix);
+            return false;
+        }
+    }
+    return true;
+}
+#endif /* if UNIX_SOCK_SUPPORT */
+
+static void
+man_accept(struct management *man)
+{
+    struct link_socket_actual act;
+    CLEAR(act);
+
+    /*
+     * Accept the TCP or Unix domain socket client.
+     */
+#if UNIX_SOCK_SUPPORT
+    if (man->settings.flags & MF_UNIX_SOCK)
+    {
+        struct sockaddr_un remote;
+        man->connection.sd_cli = socket_accept_unix(man->connection.sd_top, &remote);
+        if (!man_verify_unix_peer_uid_gid(man, man->connection.sd_cli))
+        {
+            sd_close(&man->connection.sd_cli);
+        }
+    }
+    else
+#endif
+    man->connection.sd_cli = socket_do_accept(man->connection.sd_top, &act, false);
+
+    if (socket_defined(man->connection.sd_cli))
+    {
+        man->connection.remote = act.dest;
+
+        if (socket_defined(man->connection.sd_top))
+        {
+#ifdef _WIN32
+            man_stop_ne32(man);
+#endif
+        }
+
+        man_new_connection_post(man, "Client connected from");
+    }
+}
+
+static void
+man_listen(struct management *man)
+{
+    struct gc_arena gc = gc_new();
+
+    /*
+     * Initialize state
+     */
+    man->connection.state = MS_LISTEN;
+    man->connection.sd_cli = SOCKET_UNDEFINED;
+
+    /*
+     * Initialize listening socket
+     */
+    if (man->connection.sd_top == SOCKET_UNDEFINED)
+    {
+#if UNIX_SOCK_SUPPORT
+        if (man->settings.flags & MF_UNIX_SOCK)
+        {
+            man_delete_unix_socket(man);
+            man->connection.sd_top = create_socket_unix();
+            socket_bind_unix(man->connection.sd_top, &man->settings.local_unix, "MANAGEMENT");
+        }
+        else
+#endif
+        {
+            man->connection.sd_top = create_socket_tcp(man->settings.local);
+            socket_bind(man->connection.sd_top, man->settings.local,
+                        man->settings.local->ai_family, "MANAGEMENT", false);
+        }
+
+        /*
+         * Listen for connection
+         */
+        if (listen(man->connection.sd_top, 1))
+        {
+            msg(M_ERR, "MANAGEMENT: listen() failed");
+        }
+
+        /*
+         * Set misc socket properties
+         */
+        set_nonblock(man->connection.sd_top);
+
+#if UNIX_SOCK_SUPPORT
+        if (man->settings.flags & MF_UNIX_SOCK)
+        {
+            msg(D_MANAGEMENT, "MANAGEMENT: unix domain socket listening on %s",
+                sockaddr_unix_name(&man->settings.local_unix, "NULL"));
+        }
+        else
+#endif
+        msg(D_MANAGEMENT, "MANAGEMENT: TCP Socket listening on %s",
+            print_sockaddr(man->settings.local->ai_addr, &gc));
+    }
+
+#ifdef _WIN32
+    man_start_ne32(man);
+#endif
+
+    gc_free(&gc);
+}
+
+static void
+man_connect(struct management *man)
+{
+    struct gc_arena gc = gc_new();
+    int status;
+    int signal_received = 0;
+
+    /*
+     * Initialize state
+     */
+    man->connection.state = MS_INITIAL;
+    man->connection.sd_top = SOCKET_UNDEFINED;
+
+#if UNIX_SOCK_SUPPORT
+    if (man->settings.flags & MF_UNIX_SOCK)
+    {
+        man->connection.sd_cli = create_socket_unix();
+        status = socket_connect_unix(man->connection.sd_cli, &man->settings.local_unix);
+        if (!status && !man_verify_unix_peer_uid_gid(man, man->connection.sd_cli))
+        {
+#ifdef EPERM
+            status = EPERM;
+#else
+            status = 1;
+#endif
+            sd_close(&man->connection.sd_cli);
+        }
+    }
+    else
+#endif
+    {
+        man->connection.sd_cli = create_socket_tcp(man->settings.local);
+        status = openvpn_connect(man->connection.sd_cli,
+                                 man->settings.local->ai_addr,
+                                 5,
+                                 &signal_received);
+    }
+
+    if (signal_received)
+    {
+        throw_signal(signal_received);
+        goto done;
+    }
+
+    if (status)
+    {
+#if UNIX_SOCK_SUPPORT
+        if (man->settings.flags & MF_UNIX_SOCK)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO,
+                "MANAGEMENT: connect to unix socket %s failed",
+                sockaddr_unix_name(&man->settings.local_unix, "NULL"));
+        }
+        else
+#endif
+        msg(D_LINK_ERRORS | M_ERRNO,
+            "MANAGEMENT: connect to %s failed",
+            print_sockaddr(man->settings.local->ai_addr, &gc));
+        throw_signal_soft(SIGTERM, "management-connect-failed");
+        goto done;
+    }
+
+    man_record_peer_info(man);
+    man_new_connection_post(man, "Connected to management server at");
+
+done:
+    gc_free(&gc);
+}
+
+static void
+man_reset_client_socket(struct management *man, const bool exiting)
+{
+    if (socket_defined(man->connection.sd_cli))
+    {
+#ifdef _WIN32
+        man_stop_ne32(man);
+#endif
+        man_close_socket(man, man->connection.sd_cli);
+        man->connection.sd_cli = SOCKET_UNDEFINED;
+        man->connection.state = MS_INITIAL;
+        command_line_reset(man->connection.in);
+        buffer_list_reset(man->connection.out);
+#ifdef MANAGEMENT_IN_EXTRA
+        in_extra_reset(&man->connection, IER_RESET);
+#endif
+        msg(D_MANAGEMENT, "MANAGEMENT: Client disconnected");
+    }
+    if (!exiting)
+    {
+#ifdef ENABLE_CRYPTO
+        if (man->settings.flags & MF_FORGET_DISCONNECT)
+        {
+            ssl_purge_auth(false);
+        }
+#endif
+        if (man->settings.flags & MF_SIGNAL)
+        {
+            int mysig = man_mod_signal(man, SIGUSR1);
+            if (mysig >= 0)
+            {
+                msg(D_MANAGEMENT, "MANAGEMENT: Triggering management signal");
+                throw_signal_soft(mysig, "management-disconnect");
+            }
+        }
+
+        if (man->settings.flags & MF_CONNECT_AS_CLIENT)
+        {
+            msg(D_MANAGEMENT, "MANAGEMENT: Triggering management exit");
+            throw_signal_soft(SIGTERM, "management-exit");
+        }
+        else
+        {
+            man_listen(man);
+        }
+    }
+}
+
+static void
+man_process_command(struct management *man, const char *line)
+{
+    struct gc_arena gc = gc_new();
+    struct status_output *so;
+    int nparms;
+    char *parms[MAX_PARMS+1];
+
+    CLEAR(parms);
+    so = status_open(NULL, 0, -1, &man->persist.vout, 0);
+#ifdef MANAGEMENT_IN_EXTRA
+    in_extra_reset(&man->connection, IER_RESET);
+#endif
+
+    if (man_password_needed(man))
+    {
+        man_check_password(man, line);
+    }
+    else
+    {
+        nparms = parse_line(line, parms, MAX_PARMS, "TCP", 0, M_CLIENT, &gc);
+        if (parms[0] && streq(parms[0], "password"))
+        {
+            msg(D_MANAGEMENT_DEBUG, "MANAGEMENT: CMD 'password [...]'");
+        }
+        else if (!streq(line, "load-stats"))
+        {
+            msg(D_MANAGEMENT_DEBUG, "MANAGEMENT: CMD '%s'", line);
+        }
+
+#if 0
+        /* DEBUGGING -- print args */
+        {
+            int i;
+            for (i = 0; i < nparms; ++i)
+            {
+                msg(M_INFO, "[%d] '%s'", i, parms[i]);
+            }
+        }
+#endif
+
+        if (nparms > 0)
+        {
+            man_dispatch_command(man, so, (const char **)parms, nparms);
+        }
+    }
+
+    CLEAR(parms);
+    status_close(so);
+    gc_free(&gc);
+}
+
+static bool
+man_io_error(struct management *man, const char *prefix)
+{
+    const int err = openvpn_errno();
+
+    if (!ignore_sys_error(err))
+    {
+        struct gc_arena gc = gc_new();
+        msg(D_MANAGEMENT, "MANAGEMENT: TCP %s error: %s", prefix,
+            strerror(err));
+        gc_free(&gc);
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+#ifdef TARGET_ANDROID
+static ssize_t
+man_send_with_fd(int fd, void *ptr, size_t nbytes, int flags, int sendfd)
+{
+    struct msghdr msg;
+    struct iovec iov[1];
+
+    union {
+        struct cmsghdr cm;
+        char control[CMSG_SPACE(sizeof(int))];
+    } control_un;
+    struct cmsghdr *cmptr;
+
+    msg.msg_control = control_un.control;
+    msg.msg_controllen = sizeof(control_un.control);
+
+    cmptr = CMSG_FIRSTHDR(&msg);
+    cmptr->cmsg_len = CMSG_LEN(sizeof(int));
+    cmptr->cmsg_level = SOL_SOCKET;
+    cmptr->cmsg_type = SCM_RIGHTS;
+    *((int *) CMSG_DATA(cmptr)) = sendfd;
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+
+    iov[0].iov_base = ptr;
+    iov[0].iov_len = nbytes;
+    msg.msg_iov = iov;
+    msg.msg_iovlen = 1;
+
+    return (sendmsg(fd, &msg, flags));
+}
+
+static ssize_t
+man_recv_with_fd(int fd, void *ptr, size_t nbytes, int flags, int *recvfd)
+{
+    struct msghdr msghdr;
+    struct iovec iov[1];
+    ssize_t n;
+
+    union {
+        struct cmsghdr cm;
+        char control[CMSG_SPACE(sizeof(int))];
+    } control_un;
+    struct cmsghdr  *cmptr;
+
+    msghdr.msg_control  = control_un.control;
+    msghdr.msg_controllen = sizeof(control_un.control);
+
+    msghdr.msg_name = NULL;
+    msghdr.msg_namelen = 0;
+
+    iov[0].iov_base = ptr;
+    iov[0].iov_len = nbytes;
+    msghdr.msg_iov = iov;
+    msghdr.msg_iovlen = 1;
+
+    if ( (n = recvmsg(fd, &msghdr, flags)) <= 0)
+    {
+        return (n);
+    }
+
+    if ( (cmptr = CMSG_FIRSTHDR(&msghdr)) != NULL
+         && cmptr->cmsg_len == CMSG_LEN(sizeof(int)))
+    {
+        if (cmptr->cmsg_level != SOL_SOCKET)
+        {
+            msg(M_ERR, "control level != SOL_SOCKET");
+        }
+        if (cmptr->cmsg_type != SCM_RIGHTS)
+        {
+            msg(M_ERR, "control type != SCM_RIGHTS");
+        }
+        *recvfd = *((int *) CMSG_DATA(cmptr));
+    }
+    else
+    {
+        *recvfd = -1;       /* descriptor was not passed */
+
+    }
+    return (n);
+}
+
+/*
+ * The android control method will instruct the GUI part of openvpn to do
+ * the route/ifconfig/open tun command.   See doc/android.txt for details.
+ */
+bool
+management_android_control(struct management *man, const char *command, const char *msg)
+{
+    struct user_pass up;
+    CLEAR(up);
+    strncpy(up.username, msg, sizeof(up.username)-1);
+
+    management_query_user_pass(management, &up, command, GET_USER_PASS_NEED_OK,(void *) 0);
+    return strcmp("ok", up.password)==0;
+}
+
+/*
+ * In Android 4.4 it is not possible to open a new tun device and then close the
+ * old tun device without breaking the whole VPNService stack until the device
+ * is rebooted. This management method ask the UI what method should be taken to
+ * ensure the optimal solution for the situation
+ */
+int
+managment_android_persisttun_action(struct management *man)
+{
+    struct user_pass up;
+    CLEAR(up);
+    strcpy(up.username,"tunmethod");
+    management_query_user_pass(management, &up, "PERSIST_TUN_ACTION",
+                               GET_USER_PASS_NEED_OK,(void *) 0);
+    if (!strcmp("NOACTION", up.password))
+    {
+        return ANDROID_KEEP_OLD_TUN;
+    }
+    else if (!strcmp("OPEN_AFTER_CLOSE", up.password))
+    {
+        return ANDROID_OPEN_AFTER_CLOSE;
+    }
+    else if (!strcmp("OPEN_BEFORE_CLOSE", up.password))
+    {
+        return ANDROID_OPEN_BEFORE_CLOSE;
+    }
+    else
+    {
+        msg(M_ERR, "Got unrecognised '%s' from management for PERSIST_TUN_ACTION query", up.password);
+    }
+
+    ASSERT(0);
+    return ANDROID_OPEN_AFTER_CLOSE;
+}
+
+
+#endif /* ifdef TARGET_ANDROID */
+
+static int
+man_read(struct management *man)
+{
+    /*
+     * read command line from socket
+     */
+    unsigned char buf[256];
+    int len = 0;
+
+#ifdef TARGET_ANDROID
+    int fd;
+    len = man_recv_with_fd(man->connection.sd_cli, buf, sizeof(buf), MSG_NOSIGNAL, &fd);
+    if (fd >= 0)
+    {
+        man->connection.lastfdreceived = fd;
+    }
+#else  /* ifdef TARGET_ANDROID */
+    len = recv(man->connection.sd_cli, buf, sizeof(buf), MSG_NOSIGNAL);
+#endif
+
+    if (len == 0)
+    {
+        man_reset_client_socket(man, false);
+    }
+    else if (len > 0)
+    {
+        bool processed_command = false;
+
+        ASSERT(len <= (int) sizeof(buf));
+        command_line_add(man->connection.in, buf, len);
+
+        /*
+         * Reset output object
+         */
+        buffer_list_reset(man->connection.out);
+
+        /*
+         * process command line if complete
+         */
+        {
+            const char *line;
+            while ((line = command_line_get(man->connection.in)))
+            {
+#ifdef MANAGEMENT_IN_EXTRA
+                if (man->connection.in_extra)
+                {
+                    if (!strcmp(line, "END"))
+                    {
+                        in_extra_dispatch(man);
+                    }
+                    else
+                    {
+                        buffer_list_push(man->connection.in_extra, line);
+                    }
+                }
+                else
+#endif
+                man_process_command(man, (char *) line);
+                if (man->connection.halt)
+                {
+                    break;
+                }
+                command_line_next(man->connection.in);
+                processed_command = true;
+            }
+        }
+
+        /*
+         * Reset output state to MS_CC_WAIT_(READ|WRITE)
+         */
+        if (man->connection.halt)
+        {
+            man_reset_client_socket(man, false);
+            len = 0;
+        }
+        else
+        {
+            if (processed_command)
+            {
+                man_prompt(man);
+            }
+            man_update_io_state(man);
+        }
+    }
+    else /* len < 0 */
+    {
+        if (man_io_error(man, "recv"))
+        {
+            man_reset_client_socket(man, false);
+        }
+    }
+    return len;
+}
+
+static int
+man_write(struct management *man)
+{
+    const int size_hint = 1024;
+    int sent = 0;
+    const struct buffer *buf;
+
+    buffer_list_aggregate(man->connection.out, size_hint);
+    buf = buffer_list_peek(man->connection.out);
+    if (buf && BLEN(buf))
+    {
+        const int len = min_int(size_hint, BLEN(buf));
+#ifdef TARGET_ANDROID
+        if (man->connection.fdtosend > 0)
+        {
+            sent = man_send_with_fd(man->connection.sd_cli, BPTR(buf), len, MSG_NOSIGNAL,man->connection.fdtosend);
+            man->connection.fdtosend = -1;
+        }
+        else
+#endif
+        sent = send(man->connection.sd_cli, BPTR(buf), len, MSG_NOSIGNAL);
+        if (sent >= 0)
+        {
+            buffer_list_advance(man->connection.out, sent);
+        }
+        else if (sent < 0)
+        {
+            if (man_io_error(man, "send"))
+            {
+                man_reset_client_socket(man, false);
+            }
+        }
+    }
+
+    /*
+     * Reset output state to MS_CC_WAIT_(READ|WRITE)
+     */
+    man_update_io_state(man);
+
+    return sent;
+}
+
+static void
+man_connection_clear(struct man_connection *mc)
+{
+    CLEAR(*mc);
+
+    /* set initial state */
+    mc->state = MS_INITIAL;
+
+    /* clear socket descriptors */
+    mc->sd_top = SOCKET_UNDEFINED;
+    mc->sd_cli = SOCKET_UNDEFINED;
+}
+
+static void
+man_persist_init(struct management *man,
+                 const int log_history_cache,
+                 const int echo_buffer_size,
+                 const int state_buffer_size)
+{
+    struct man_persist *mp = &man->persist;
+    if (!mp->defined)
+    {
+        CLEAR(*mp);
+
+        /* initialize log history store */
+        mp->log = log_history_init(log_history_cache);
+
+        /*
+         * Initialize virtual output object, so that functions
+         * which write to a virtual_output object can be redirected
+         * here to the management object.
+         */
+        mp->vout.func = virtual_output_callback_func;
+        mp->vout.arg = man;
+        mp->vout.flags_default = M_CLIENT;
+        msg_set_virtual_output(&mp->vout);
+
+        /*
+         * Initialize --echo list
+         */
+        man->persist.echo = log_history_init(echo_buffer_size);
+
+        /*
+         * Initialize --state list
+         */
+        man->persist.state = log_history_init(state_buffer_size);
+
+        mp->defined = true;
+    }
+}
+
+static void
+man_persist_close(struct man_persist *mp)
+{
+    if (mp->log)
+    {
+        msg_set_virtual_output(NULL);
+        log_history_close(mp->log);
+    }
+
+    if (mp->echo)
+    {
+        log_history_close(mp->echo);
+    }
+
+    if (mp->state)
+    {
+        log_history_close(mp->state);
+    }
+
+    CLEAR(*mp);
+}
+
+static void
+man_settings_init(struct man_settings *ms,
+                  const char *addr,
+                  const char *port,
+                  const char *pass_file,
+                  const char *client_user,
+                  const char *client_group,
+                  const int log_history_cache,
+                  const int echo_buffer_size,
+                  const int state_buffer_size,
+                  const char *write_peer_info_file,
+                  const int remap_sigusr1,
+                  const unsigned int flags)
+{
+    if (!ms->defined)
+    {
+        CLEAR(*ms);
+
+        ms->flags = flags;
+        ms->client_uid = -1;
+        ms->client_gid = -1;
+
+        /*
+         * Get username/password
+         */
+        if (pass_file)
+        {
+            get_user_pass(&ms->up, pass_file, "Management", GET_USER_PASS_PASSWORD_ONLY);
+        }
+
+        /*
+         * lookup client UID/GID if specified
+         */
+        if (client_user)
+        {
+            struct platform_state_user s;
+            platform_user_get(client_user, &s);
+            ms->client_uid = platform_state_user_uid(&s);
+            msg(D_MANAGEMENT, "MANAGEMENT: client_uid=%d", ms->client_uid);
+            ASSERT(ms->client_uid >= 0);
+        }
+        if (client_group)
+        {
+            struct platform_state_group s;
+            platform_group_get(client_group, &s);
+            ms->client_gid = platform_state_group_gid(&s);
+            msg(D_MANAGEMENT, "MANAGEMENT: client_gid=%d", ms->client_gid);
+            ASSERT(ms->client_gid >= 0);
+        }
+
+        ms->write_peer_info_file = string_alloc(write_peer_info_file, NULL);
+
+#if UNIX_SOCK_SUPPORT
+        if (ms->flags & MF_UNIX_SOCK)
+        {
+            sockaddr_unix_init(&ms->local_unix, addr);
+        }
+        else
+#endif
+        {
+
+            /*
+             * Run management over tunnel, or
+             * separate channel?
+             */
+            if (streq(addr, "tunnel") && !(flags & MF_CONNECT_AS_CLIENT))
+            {
+                ms->management_over_tunnel = true;
+            }
+            else
+            {
+                int status;
+                int resolve_flags = GETADDR_RESOLVE|GETADDR_WARN_ON_SIGNAL|GETADDR_FATAL;
+
+                if (!(flags & MF_CONNECT_AS_CLIENT))
+                {
+                    resolve_flags |= GETADDR_PASSIVE;
+                }
+
+                status = openvpn_getaddrinfo(resolve_flags, addr, port, 0,
+                                             NULL, AF_UNSPEC, &ms->local);
+                ASSERT(status==0);
+            }
+        }
+
+        /*
+         * Log history and echo buffer may need to be resized
+         */
+        ms->log_history_cache = log_history_cache;
+        ms->echo_buffer_size = echo_buffer_size;
+        ms->state_buffer_size = state_buffer_size;
+
+        /*
+         * Set remap sigusr1 flags
+         */
+        if (remap_sigusr1 == SIGHUP)
+        {
+            ms->mansig |= MANSIG_MAP_USR1_TO_HUP;
+        }
+        else if (remap_sigusr1 == SIGTERM)
+        {
+            ms->mansig |= MANSIG_MAP_USR1_TO_TERM;
+        }
+
+        ms->defined = true;
+    }
+}
+
+static void
+man_settings_close(struct man_settings *ms)
+{
+    if (ms->local)
+    {
+        freeaddrinfo(ms->local);
+    }
+    free(ms->write_peer_info_file);
+    CLEAR(*ms);
+}
+
+
+static void
+man_connection_init(struct management *man)
+{
+    if (man->connection.state == MS_INITIAL)
+    {
+#ifdef _WIN32
+        /*
+         * This object is a sort of TCP/IP helper
+         * for Windows.
+         */
+        net_event_win32_init(&man->connection.ne32);
+#endif
+
+        /*
+         * Allocate helper objects for command line input and
+         * command output from/to the socket.
+         */
+        man->connection.in = command_line_new(1024);
+        man->connection.out = buffer_list_new(0);
+
+        /*
+         * Initialize event set for standalone usage, when we are
+         * running outside of the primary event loop.
+         */
+        {
+            int maxevents = 1;
+            man->connection.es = event_set_init(&maxevents, EVENT_METHOD_FAST);
+        }
+
+        /*
+         * Listen/connect socket
+         */
+        if (man->settings.flags & MF_CONNECT_AS_CLIENT)
+        {
+            man_connect(man);
+        }
+        else
+        {
+            man_listen(man);
+        }
+    }
+}
+
+static void
+man_connection_close(struct management *man)
+{
+    struct man_connection *mc = &man->connection;
+
+    if (mc->es)
+    {
+        event_free(mc->es);
+    }
+#ifdef _WIN32
+    net_event_win32_close(&mc->ne32);
+#endif
+    if (socket_defined(mc->sd_top))
+    {
+        man_close_socket(man, mc->sd_top);
+        man_delete_unix_socket(man);
+    }
+    if (socket_defined(mc->sd_cli))
+    {
+        man_close_socket(man, mc->sd_cli);
+    }
+    if (mc->in)
+    {
+        command_line_free(mc->in);
+    }
+    if (mc->out)
+    {
+        buffer_list_free(mc->out);
+    }
+#ifdef MANAGEMENT_IN_EXTRA
+    in_extra_reset(&man->connection, IER_RESET);
+#endif
+#ifdef MANAGMENT_EXTERNAL_KEY
+    buffer_list_free(mc->ext_key_input);
+#endif
+    man_connection_clear(mc);
+}
+
+struct management *
+management_init(void)
+{
+    struct management *man;
+    ALLOC_OBJ_CLEAR(man, struct management);
+
+    man_persist_init(man,
+                     MANAGEMENT_LOG_HISTORY_INITIAL_SIZE,
+                     MANAGEMENT_ECHO_BUFFER_SIZE,
+                     MANAGEMENT_STATE_BUFFER_SIZE);
+
+    man_connection_clear(&man->connection);
+
+    return man;
+}
+
+bool
+management_open(struct management *man,
+                const char *addr,
+                const char *port,
+                const char *pass_file,
+                const char *client_user,
+                const char *client_group,
+                const int log_history_cache,
+                const int echo_buffer_size,
+                const int state_buffer_size,
+                const char *write_peer_info_file,
+                const int remap_sigusr1,
+                const unsigned int flags)
+{
+    bool ret = false;
+
+    /*
+     * Save the settings only if they have not
+     * been saved before.
+     */
+    man_settings_init(&man->settings,
+                      addr,
+                      port,
+                      pass_file,
+                      client_user,
+                      client_group,
+                      log_history_cache,
+                      echo_buffer_size,
+                      state_buffer_size,
+                      write_peer_info_file,
+                      remap_sigusr1,
+                      flags);
+
+    /*
+     * The log is initially sized to MANAGEMENT_LOG_HISTORY_INITIAL_SIZE,
+     * but may be changed here.  Ditto for echo and state buffers.
+     */
+    log_history_resize(man->persist.log, man->settings.log_history_cache);
+    log_history_resize(man->persist.echo, man->settings.echo_buffer_size);
+    log_history_resize(man->persist.state, man->settings.state_buffer_size);
+
+    /*
+     * If connection object is uninitialized and we are not doing
+     * over-the-tunnel management, then open (listening) connection.
+     */
+    if (man->connection.state == MS_INITIAL)
+    {
+        if (!man->settings.management_over_tunnel)
+        {
+            man_connection_init(man);
+            ret = true;
+        }
+    }
+
+    return ret;
+}
+
+void
+management_close(struct management *man)
+{
+    man_output_list_push_finalize(man); /* flush output queue */
+    man_connection_close(man);
+    man_settings_close(&man->settings);
+    man_persist_close(&man->persist);
+    free(man);
+}
+
+void
+management_set_callback(struct management *man,
+                        const struct management_callback *cb)
+{
+    man->persist.standalone_disabled = true;
+    man->persist.callback = *cb;
+}
+
+void
+management_clear_callback(struct management *man)
+{
+    man->persist.standalone_disabled = false;
+    man->persist.hold_release = false;
+    CLEAR(man->persist.callback);
+    man_output_list_push_finalize(man); /* flush output queue */
+}
+
+void
+management_set_state(struct management *man,
+                     const int state,
+                     const char *detail,
+                     const in_addr_t *tun_local_ip,
+                     const struct in6_addr *tun_local_ip6,
+                     const struct openvpn_sockaddr *local,
+                     const struct openvpn_sockaddr *remote)
+{
+    if (man->persist.state && (!(man->settings.flags & MF_SERVER) || state < OPENVPN_STATE_CLIENT_BASE))
+    {
+        struct gc_arena gc = gc_new();
+        struct log_entry e;
+        const char *out = NULL;
+
+        update_time();
+        CLEAR(e);
+        e.timestamp = now;
+        e.u.state = state;
+        e.string = detail;
+        if (tun_local_ip)
+        {
+            e.local_ip = *tun_local_ip;
+        }
+        if (tun_local_ip6)
+        {
+            e.local_ip6 = *tun_local_ip6;
+        }
+        if (local)
+        {
+            e.local_sock = *local;
+        }
+        if (remote)
+        {
+            e.remote_sock = *remote;
+        }
+
+        log_history_add(man->persist.state, &e);
+
+        if (man->connection.state_realtime)
+        {
+            out = log_entry_print(&e, LOG_PRINT_STATE_PREFIX
+                                  |   LOG_PRINT_INT_DATE
+                                  |   LOG_PRINT_STATE
+                                  |   LOG_PRINT_LOCAL_IP
+                                  |   LOG_PRINT_REMOTE_IP
+                                  |   LOG_PRINT_CRLF
+                                  |   LOG_ECHO_TO_LOG, &gc);
+        }
+
+        if (out)
+        {
+            man_output_list_push(man, out);
+        }
+
+        gc_free(&gc);
+    }
+}
+
+static bool
+env_filter_match(const char *env_str, const int env_filter_level)
+{
+    static const char *env_names[] = {
+        "username=",
+        "password=",
+        "X509_0_CN=",
+        "tls_serial_",
+        "untrusted_ip=",
+        "ifconfig_local=",
+        "ifconfig_netmask=",
+        "daemon_start_time=",
+        "daemon_pid=",
+        "dev=",
+        "ifconfig_pool_remote_ip=",
+        "ifconfig_pool_netmask=",
+        "time_duration=",
+        "bytes_sent=",
+        "bytes_received="
+    };
+
+    if (env_filter_level == 0)
+    {
+        return true;
+    }
+    else if (env_filter_level <= 1 && !strncmp(env_str, "X509_", 5))
+    {
+        return true;
+    }
+    else if (env_filter_level <= 2)
+    {
+        size_t i;
+        for (i = 0; i < SIZE(env_names); ++i)
+        {
+            const char *en = env_names[i];
+            const size_t len = strlen(en);
+            if (!strncmp(env_str, en, len))
+            {
+                return true;
+            }
+        }
+        return false;
+    }
+    return false;
+}
+
+static void
+man_output_env(const struct env_set *es, const bool tail, const int env_filter_level, const char *prefix)
+{
+    if (es)
+    {
+        struct env_item *e;
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            if (e->string && (!env_filter_level || env_filter_match(e->string, env_filter_level)))
+            {
+                msg(M_CLIENT, ">%s:ENV,%s", prefix, e->string);
+            }
+        }
+    }
+    if (tail)
+    {
+        msg(M_CLIENT, ">%s:ENV,END", prefix);
+    }
+}
+
+static void
+man_output_extra_env(struct management *man, const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+    struct env_set *es = env_set_create(&gc);
+    if (man->persist.callback.n_clients)
+    {
+        const int nclients = (*man->persist.callback.n_clients)(man->persist.callback.arg);
+        setenv_int(es, "n_clients", nclients);
+    }
+    man_output_env(es, false, man->connection.env_filter_level, prefix);
+    gc_free(&gc);
+}
+
+void
+management_up_down(struct management *man, const char *updown, const struct env_set *es)
+{
+    if (man->settings.flags & MF_UP_DOWN)
+    {
+        msg(M_CLIENT, ">UPDOWN:%s", updown);
+        man_output_env(es, true, 0, "UPDOWN");
+    }
+}
+
+void
+management_notify(struct management *man, const char *severity, const char *type, const char *text)
+{
+    msg(M_CLIENT, ">NOTIFY:%s,%s,%s", severity, type, text);
+}
+
+void
+management_notify_generic(struct management *man, const char *str)
+{
+    msg(M_CLIENT, "%s", str);
+}
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+static void
+man_output_peer_info_env(struct management *man, struct man_def_auth_context *mdac)
+{
+    char line[256];
+    if (man->persist.callback.get_peer_info)
+    {
+        const char *peer_info = (*man->persist.callback.get_peer_info)(man->persist.callback.arg, mdac->cid);
+        if (peer_info)
+        {
+            struct buffer buf;
+            buf_set_read(&buf, (const uint8_t *) peer_info, strlen(peer_info));
+            while (buf_parse(&buf, '\n', line, sizeof(line)))
+            {
+                chomp(line);
+                if (validate_peer_info_line(line))
+                {
+                    msg(M_CLIENT, ">CLIENT:ENV,%s", line);
+                }
+                else
+                {
+                    msg(D_MANAGEMENT, "validation failed on peer_info line received from client");
+                }
+            }
+        }
+    }
+}
+
+void
+management_notify_client_needing_auth(struct management *management,
+                                      const unsigned int mda_key_id,
+                                      struct man_def_auth_context *mdac,
+                                      const struct env_set *es)
+{
+    if (!(mdac->flags & DAF_CONNECTION_CLOSED))
+    {
+        const char *mode = "CONNECT";
+        if (mdac->flags & DAF_CONNECTION_ESTABLISHED)
+        {
+            mode = "REAUTH";
+        }
+        msg(M_CLIENT, ">CLIENT:%s,%lu,%u", mode, mdac->cid, mda_key_id);
+        man_output_extra_env(management, "CLIENT");
+        if (management->connection.env_filter_level>0)
+        {
+            man_output_peer_info_env(management, mdac);
+        }
+        man_output_env(es, true, management->connection.env_filter_level, "CLIENT");
+        mdac->flags |= DAF_INITIAL_AUTH;
+    }
+}
+
+void
+management_connection_established(struct management *management,
+                                  struct man_def_auth_context *mdac,
+                                  const struct env_set *es)
+{
+    mdac->flags |= DAF_CONNECTION_ESTABLISHED;
+    msg(M_CLIENT, ">CLIENT:ESTABLISHED,%lu", mdac->cid);
+    man_output_extra_env(management, "CLIENT");
+    man_output_env(es, true, management->connection.env_filter_level, "CLIENT");
+}
+
+void
+management_notify_client_close(struct management *management,
+                               struct man_def_auth_context *mdac,
+                               const struct env_set *es)
+{
+    if ((mdac->flags & DAF_INITIAL_AUTH) && !(mdac->flags & DAF_CONNECTION_CLOSED))
+    {
+        msg(M_CLIENT, ">CLIENT:DISCONNECT,%lu", mdac->cid);
+        man_output_env(es, true, management->connection.env_filter_level, "CLIENT");
+        mdac->flags |= DAF_CONNECTION_CLOSED;
+    }
+}
+
+void
+management_learn_addr(struct management *management,
+                      struct man_def_auth_context *mdac,
+                      const struct mroute_addr *addr,
+                      const bool primary)
+{
+    struct gc_arena gc = gc_new();
+    if ((mdac->flags & DAF_INITIAL_AUTH) && !(mdac->flags & DAF_CONNECTION_CLOSED))
+    {
+        msg(M_CLIENT, ">CLIENT:ADDRESS,%lu,%s,%d",
+            mdac->cid,
+            mroute_addr_print_ex(addr, MAPF_SUBNET, &gc),
+            BOOL_CAST(primary));
+    }
+    gc_free(&gc);
+}
+
+#endif /* MANAGEMENT_DEF_AUTH */
+
+void
+management_echo(struct management *man, const char *string, const bool pull)
+{
+    if (man->persist.echo)
+    {
+        struct gc_arena gc = gc_new();
+        struct log_entry e;
+        const char *out = NULL;
+
+        update_time();
+        CLEAR(e);
+        e.timestamp = now;
+        e.string = string;
+        e.u.intval = BOOL_CAST(pull);
+
+        log_history_add(man->persist.echo, &e);
+
+        if (man->connection.echo_realtime)
+        {
+            out = log_entry_print(&e, LOG_PRINT_INT_DATE|LOG_PRINT_ECHO_PREFIX|LOG_PRINT_CRLF|MANAGEMENT_ECHO_FLAGS, &gc);
+        }
+
+        if (out)
+        {
+            man_output_list_push(man, out);
+        }
+
+        gc_free(&gc);
+    }
+}
+
+void
+management_post_tunnel_open(struct management *man, const in_addr_t tun_local_ip)
+{
+    /*
+     * If we are running management over the tunnel,
+     * this is the place to initialize the connection.
+     */
+    if (man->settings.management_over_tunnel
+        && man->connection.state == MS_INITIAL)
+    {
+        /* listen on our local TUN/TAP IP address */
+        struct in_addr ia;
+        int ret;
+
+        ia.s_addr = htonl(tun_local_ip);
+        ret = openvpn_getaddrinfo(GETADDR_PASSIVE, inet_ntoa(ia), NULL, 0, NULL,
+                                  AF_INET, &man->settings.local);
+        ASSERT(ret==0);
+        man_connection_init(man);
+    }
+
+}
+
+void
+management_pre_tunnel_close(struct management *man)
+{
+    if (man->settings.management_over_tunnel)
+    {
+        man_connection_close(man);
+    }
+}
+
+void
+management_auth_failure(struct management *man, const char *type, const char *reason)
+{
+    if (reason)
+    {
+        msg(M_CLIENT, ">PASSWORD:Verification Failed: '%s' ['%s']", type, reason);
+    }
+    else
+    {
+        msg(M_CLIENT, ">PASSWORD:Verification Failed: '%s'", type);
+    }
+}
+
+void
+management_auth_token(struct management *man, const char *token)
+{
+    msg(M_CLIENT, ">PASSWORD:Auth-Token:%s", token);
+}
+
+static inline bool
+man_persist_state(unsigned int *persistent, const int n)
+{
+    if (persistent)
+    {
+        if (*persistent == (unsigned int)n)
+        {
+            return false;
+        }
+        *persistent = n;
+    }
+    return true;
+}
+
+#ifdef _WIN32
+
+void
+management_socket_set(struct management *man,
+                      struct event_set *es,
+                      void *arg,
+                      unsigned int *persistent)
+{
+    if (man->connection.state != MS_INITIAL)
+    {
+        event_t ev = net_event_win32_get_event(&man->connection.ne32);
+        net_event_win32_reset_write(&man->connection.ne32);
+
+        switch (man->connection.state)
+        {
+            case MS_LISTEN:
+                if (man_persist_state(persistent, 1))
+                {
+                    event_ctl(es, ev, EVENT_READ, arg);
+                }
+                break;
+
+            case MS_CC_WAIT_READ:
+                if (man_persist_state(persistent, 2))
+                {
+                    event_ctl(es, ev, EVENT_READ, arg);
+                }
+                break;
+
+            case MS_CC_WAIT_WRITE:
+                if (man_persist_state(persistent, 3))
+                {
+                    event_ctl(es, ev, EVENT_READ|EVENT_WRITE, arg);
+                }
+                break;
+
+            default:
+                ASSERT(0);
+        }
+    }
+}
+
+void
+management_io(struct management *man)
+{
+    if (man->connection.state != MS_INITIAL)
+    {
+        long net_events;
+        net_event_win32_reset(&man->connection.ne32);
+        net_events = net_event_win32_get_event_mask(&man->connection.ne32);
+
+        if (net_events & FD_CLOSE)
+        {
+            man_reset_client_socket(man, false);
+        }
+        else
+        {
+            if (man->connection.state == MS_LISTEN)
+            {
+                if (net_events & FD_ACCEPT)
+                {
+                    man_accept(man);
+                    net_event_win32_clear_selected_events(&man->connection.ne32, FD_ACCEPT);
+                }
+            }
+            else if (man->connection.state == MS_CC_WAIT_READ || man->connection.state == MS_CC_WAIT_WRITE)
+            {
+                if (net_events & FD_READ)
+                {
+                    while (man_read(man) > 0)
+                    {
+                    }
+                    net_event_win32_clear_selected_events(&man->connection.ne32, FD_READ);
+                }
+
+                if (net_events & FD_WRITE)
+                {
+                    int status;
+                    status = man_write(man);
+                    if (status < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
+                    {
+                        net_event_win32_clear_selected_events(&man->connection.ne32, FD_WRITE);
+                    }
+                }
+            }
+        }
+    }
+}
+
+#else  /* ifdef _WIN32 */
+
+void
+management_socket_set(struct management *man,
+                      struct event_set *es,
+                      void *arg,
+                      unsigned int *persistent)
+{
+    switch (man->connection.state)
+    {
+        case MS_LISTEN:
+            if (man_persist_state(persistent, 1))
+            {
+                event_ctl(es, man->connection.sd_top, EVENT_READ, arg);
+            }
+            break;
+
+        case MS_CC_WAIT_READ:
+            if (man_persist_state(persistent, 2))
+            {
+                event_ctl(es, man->connection.sd_cli, EVENT_READ, arg);
+            }
+            break;
+
+        case MS_CC_WAIT_WRITE:
+            if (man_persist_state(persistent, 3))
+            {
+                event_ctl(es, man->connection.sd_cli, EVENT_WRITE, arg);
+            }
+            break;
+
+        case MS_INITIAL:
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+void
+management_io(struct management *man)
+{
+    switch (man->connection.state)
+    {
+        case MS_LISTEN:
+            man_accept(man);
+            break;
+
+        case MS_CC_WAIT_READ:
+            man_read(man);
+            break;
+
+        case MS_CC_WAIT_WRITE:
+            man_write(man);
+            break;
+
+        case MS_INITIAL:
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+#endif /* ifdef _WIN32 */
+
+static inline bool
+man_standalone_ok(const struct management *man)
+{
+    return !man->settings.management_over_tunnel && man->connection.state != MS_INITIAL;
+}
+
+static bool
+man_check_for_signals(volatile int *signal_received)
+{
+    if (signal_received)
+    {
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+/*
+ * Wait for socket I/O when outside primary event loop
+ */
+static int
+man_block(struct management *man, volatile int *signal_received, const time_t expire)
+{
+    struct timeval tv;
+    struct event_set_return esr;
+    int status = -1;
+
+    if (man_standalone_ok(man))
+    {
+        while (true)
+        {
+            event_reset(man->connection.es);
+            management_socket_set(man, man->connection.es, NULL, NULL);
+            tv.tv_usec = 0;
+            tv.tv_sec = 1;
+            if (man_check_for_signals(signal_received))
+            {
+                status = -1;
+                break;
+            }
+            status = event_wait(man->connection.es, &tv, &esr, 1);
+            update_time();
+            if (man_check_for_signals(signal_received))
+            {
+                status = -1;
+                break;
+            }
+
+            if (status > 0)
+            {
+                break;
+            }
+            else if (expire && now >= expire)
+            {
+                /* set SIGINT signal if expiration time exceeded */
+                status = 0;
+                if (signal_received)
+                {
+                    *signal_received = SIGINT;
+                }
+                break;
+            }
+        }
+    }
+    return status;
+}
+
+/*
+ * Perform management socket output outside primary event loop
+ */
+static void
+man_output_standalone(struct management *man, volatile int *signal_received)
+{
+    if (man_standalone_ok(man))
+    {
+        while (man->connection.state == MS_CC_WAIT_WRITE)
+        {
+            management_io(man);
+            if (man->connection.state == MS_CC_WAIT_WRITE)
+            {
+                man_block(man, signal_received, 0);
+            }
+            if (signal_received && *signal_received)
+            {
+                break;
+            }
+        }
+    }
+}
+
+/*
+ * Process management event loop outside primary event loop
+ */
+static int
+man_standalone_event_loop(struct management *man, volatile int *signal_received, const time_t expire)
+{
+    int status = -1;
+    if (man_standalone_ok(man))
+    {
+        status = man_block(man, signal_received, expire);
+        if (status > 0)
+        {
+            management_io(man);
+        }
+    }
+    return status;
+}
+
+#define MWCC_PASSWORD_WAIT (1<<0)
+#define MWCC_HOLD_WAIT     (1<<1)
+#define MWCC_OTHER_WAIT    (1<<2)
+
+/*
+ * Block until client connects
+ */
+static void
+man_wait_for_client_connection(struct management *man,
+                               volatile int *signal_received,
+                               const time_t expire,
+                               unsigned int flags)
+{
+    ASSERT(man_standalone_ok(man));
+    if (man->connection.state == MS_LISTEN)
+    {
+        if (flags & MWCC_PASSWORD_WAIT)
+        {
+            msg(D_MANAGEMENT, "Need password(s) from management interface, waiting...");
+        }
+        if (flags & MWCC_HOLD_WAIT)
+        {
+            msg(D_MANAGEMENT, "Need hold release from management interface, waiting...");
+        }
+        if (flags & MWCC_OTHER_WAIT)
+        {
+            msg(D_MANAGEMENT, "Need information from management interface, waiting...");
+        }
+        do
+        {
+            man_standalone_event_loop(man, signal_received, expire);
+            if (signal_received && *signal_received)
+            {
+                break;
+            }
+        } while (man->connection.state == MS_LISTEN || man_password_needed(man));
+    }
+}
+
+/*
+ * Process the management event loop for sec seconds
+ */
+void
+management_event_loop_n_seconds(struct management *man, int sec)
+{
+    if (man_standalone_ok(man))
+    {
+        volatile int signal_received = 0;
+        const bool standalone_disabled_save = man->persist.standalone_disabled;
+        time_t expire = 0;
+
+        man->persist.standalone_disabled = false; /* This is so M_CLIENT messages will be correctly passed through msg() */
+
+        /* set expire time */
+        update_time();
+        if (sec)
+        {
+            expire = now + sec;
+        }
+
+        /* if no client connection, wait for one */
+        man_wait_for_client_connection(man, &signal_received, expire, 0);
+        if (signal_received)
+        {
+            return;
+        }
+
+        /* run command processing event loop */
+        do
+        {
+            man_standalone_event_loop(man, &signal_received, expire);
+            if (!signal_received)
+            {
+                man_check_for_signals(&signal_received);
+            }
+            if (signal_received)
+            {
+                return;
+            }
+            update_time();
+        } while (expire && expire > now);
+
+        /* revert state */
+        man->persist.standalone_disabled = standalone_disabled_save;
+    }
+    else
+    {
+        sleep(sec);
+    }
+}
+
+/*
+ * Get a username/password from management channel in standalone mode.
+ */
+bool
+management_query_user_pass(struct management *man,
+                           struct user_pass *up,
+                           const char *type,
+                           const unsigned int flags,
+                           const char *static_challenge)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+    if (man_standalone_ok(man))
+    {
+        volatile int signal_received = 0;
+        const bool standalone_disabled_save = man->persist.standalone_disabled;
+        struct buffer alert_msg = alloc_buf_gc(128, &gc);
+        const char *alert_type = NULL;
+        const char *prefix = NULL;
+        unsigned int up_query_mode = 0;
+#ifdef ENABLE_CLIENT_CR
+        const char *sc = NULL;
+#endif
+        ret = true;
+        man->persist.standalone_disabled = false; /* This is so M_CLIENT messages will be correctly passed through msg() */
+        man->persist.special_state_msg = NULL;
+
+        CLEAR(man->connection.up_query);
+
+        if (flags & GET_USER_PASS_NEED_OK)
+        {
+            up_query_mode = UP_QUERY_NEED_OK;
+            prefix = "NEED-OK";
+            alert_type = "confirmation";
+        }
+        else if (flags & GET_USER_PASS_NEED_STR)
+        {
+            up_query_mode = UP_QUERY_NEED_STR;
+            prefix = "NEED-STR";
+            alert_type = "string";
+        }
+        else if (flags & GET_USER_PASS_PASSWORD_ONLY)
+        {
+            up_query_mode = UP_QUERY_PASS;
+            prefix = "PASSWORD";
+            alert_type = "password";
+        }
+        else
+        {
+            up_query_mode = UP_QUERY_USER_PASS;
+            prefix = "PASSWORD";
+            alert_type = "username/password";
+#ifdef ENABLE_CLIENT_CR
+            if (static_challenge)
+            {
+                sc = static_challenge;
+            }
+#endif
+        }
+        buf_printf(&alert_msg, ">%s:Need '%s' %s",
+                   prefix,
+                   type,
+                   alert_type);
+
+        if (flags & (GET_USER_PASS_NEED_OK | GET_USER_PASS_NEED_STR))
+        {
+            buf_printf(&alert_msg, " MSG:%s", up->username);
+        }
+
+#ifdef ENABLE_CLIENT_CR
+        if (sc)
+        {
+            buf_printf(&alert_msg, " SC:%d,%s",
+                       BOOL_CAST(flags & GET_USER_PASS_STATIC_CHALLENGE_ECHO),
+                       sc);
+        }
+#endif
+
+        man_wait_for_client_connection(man, &signal_received, 0, MWCC_PASSWORD_WAIT);
+        if (signal_received)
+        {
+            ret = false;
+        }
+
+        if (ret)
+        {
+            man->persist.special_state_msg = BSTR(&alert_msg);
+            msg(M_CLIENT, "%s", man->persist.special_state_msg);
+
+            /* tell command line parser which info we need */
+            man->connection.up_query_mode = up_query_mode;
+            man->connection.up_query_type = type;
+
+            /* run command processing event loop until we get our username/password/response */
+            do
+            {
+                man_standalone_event_loop(man, &signal_received, 0);
+                if (!signal_received)
+                {
+                    man_check_for_signals(&signal_received);
+                }
+                if (signal_received)
+                {
+                    ret = false;
+                    break;
+                }
+            } while (!man->connection.up_query.defined);
+        }
+
+        /* revert state */
+        man->connection.up_query_mode = UP_QUERY_DISABLED;
+        man->connection.up_query_type = NULL;
+        man->persist.standalone_disabled = standalone_disabled_save;
+        man->persist.special_state_msg = NULL;
+
+        /* pass through blank passwords */
+        if (!strcmp(man->connection.up_query.password, blank_up))
+        {
+            CLEAR(man->connection.up_query.password);
+        }
+
+        /*
+         * Transfer u/p to return object, zero any record
+         * we hold in the management object.
+         */
+        if (ret)
+        {
+            /* preserve caller's settings */
+            man->connection.up_query.nocache = up->nocache;
+            man->connection.up_query.wait_for_push = up->wait_for_push;
+            *up = man->connection.up_query;
+        }
+        secure_memzero(&man->connection.up_query, sizeof(man->connection.up_query));
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+static int
+management_query_multiline(struct management *man,
+                           const char *b64_data, const char *prompt, const char *cmd, int *state, struct buffer_list **input)
+{
+    struct gc_arena gc = gc_new();
+    int ret = 0;
+    volatile int signal_received = 0;
+    struct buffer alert_msg = clear_buf();
+    const bool standalone_disabled_save = man->persist.standalone_disabled;
+    struct man_connection *mc = &man->connection;
+
+    if (man_standalone_ok(man))
+    {
+        man->persist.standalone_disabled = false; /* This is so M_CLIENT messages will be correctly passed through msg() */
+        man->persist.special_state_msg = NULL;
+
+        *state = EKS_SOLICIT;
+
+        if (b64_data)
+        {
+            alert_msg = alloc_buf_gc(strlen(b64_data)+strlen(prompt)+3, &gc);
+            buf_printf(&alert_msg, ">%s:%s", prompt, b64_data);
+        }
+        else
+        {
+            alert_msg = alloc_buf_gc(strlen(prompt)+3, &gc);
+            buf_printf(&alert_msg, ">%s", prompt);
+        }
+
+        man_wait_for_client_connection(man, &signal_received, 0, MWCC_OTHER_WAIT);
+
+        if (signal_received)
+        {
+            goto done;
+        }
+
+        man->persist.special_state_msg = BSTR(&alert_msg);
+        msg(M_CLIENT, "%s", man->persist.special_state_msg);
+
+        /* run command processing event loop until we get our signature */
+        do
+        {
+            man_standalone_event_loop(man, &signal_received, 0);
+            if (!signal_received)
+            {
+                man_check_for_signals(&signal_received);
+            }
+            if (signal_received)
+            {
+                goto done;
+            }
+        } while (*state != EKS_READY);
+
+        ret = 1;
+    }
+
+done:
+    if (*state == EKS_READY && ret)
+    {
+        msg(M_CLIENT, "SUCCESS: %s command succeeded", cmd);
+    }
+    else if (*state == EKS_INPUT || *state == EKS_READY)
+    {
+        msg(M_CLIENT, "ERROR: %s command failed", cmd);
+    }
+
+    /* revert state */
+    man->persist.standalone_disabled = standalone_disabled_save;
+    man->persist.special_state_msg = NULL;
+    in_extra_reset(mc, IER_RESET);
+    *state = EKS_UNDEF;
+
+    gc_free(&gc);
+    return ret;
+}
+
+static char *
+/* returns allocated base64 signature */
+management_query_multiline_flatten_newline(struct management *man,
+                                           const char *b64_data, const char *prompt, const char *cmd, int *state, struct buffer_list **input)
+{
+    int ok;
+    char *result = NULL;
+    struct buffer *buf;
+
+    ok = management_query_multiline(man, b64_data, prompt, cmd, state, input);
+    if (ok && buffer_list_defined(*input))
+    {
+        buffer_list_aggregate_separator(*input, 10000, "\n");
+        buf = buffer_list_peek(*input);
+        if (buf && BLEN(buf) > 0)
+        {
+            result = (char *) malloc(BLEN(buf)+1);
+            check_malloc_return(result);
+            memcpy(result, buf->data, BLEN(buf));
+            result[BLEN(buf)] = '\0';
+        }
+    }
+
+    buffer_list_free(*input);
+    *input = NULL;
+
+    return result;
+}
+
+static char *
+/* returns allocated base64 signature */
+management_query_multiline_flatten(struct management *man,
+                                   const char *b64_data, const char *prompt, const char *cmd, int *state, struct buffer_list **input)
+{
+    int ok;
+    char *result = NULL;
+    struct buffer *buf;
+
+    ok = management_query_multiline(man, b64_data, prompt, cmd, state, input);
+    if (ok && buffer_list_defined(*input))
+    {
+        buffer_list_aggregate(*input, 2048);
+        buf = buffer_list_peek(*input);
+        if (buf && BLEN(buf) > 0)
+        {
+            result = (char *) malloc(BLEN(buf)+1);
+            check_malloc_return(result);
+            memcpy(result, buf->data, BLEN(buf));
+            result[BLEN(buf)] = '\0';
+        }
+    }
+
+    buffer_list_free(*input);
+    *input = NULL;
+
+    return result;
+}
+
+char *
+/* returns allocated base64 signature */
+management_query_rsa_sig(struct management *man,
+                         const char *b64_data)
+{
+    return management_query_multiline_flatten(man, b64_data, "RSA_SIGN", "rsa-sign",
+                                              &man->connection.ext_key_state, &man->connection.ext_key_input);
+}
+
+
+char *
+management_query_cert(struct management *man, const char *cert_name)
+{
+    const char prompt_1[] = "NEED-CERTIFICATE:";
+    struct buffer buf_prompt = alloc_buf(strlen(cert_name) + 20);
+    buf_write(&buf_prompt, prompt_1, strlen(prompt_1));
+    buf_write(&buf_prompt, cert_name, strlen(cert_name)+1); /* +1 for \0 */
+
+    char *result;
+    result = management_query_multiline_flatten_newline(management,
+                                                        NULL, (char *)buf_bptr(&buf_prompt), "certificate",
+                                                        &man->connection.ext_cert_state, &man->connection.ext_cert_input);
+    free_buf(&buf_prompt);
+    return result;
+}
+
+#endif /* ifdef MANAGMENT_EXTERNAL_KEY */
+
+/*
+ * Return true if management_hold() would block
+ */
+bool
+management_would_hold(struct management *man)
+{
+    return (man->settings.flags & MF_HOLD) && !man->persist.hold_release && man_standalone_ok(man);
+}
+
+/*
+ * Return true if (from the management interface's perspective) OpenVPN should
+ * daemonize.
+ */
+bool
+management_should_daemonize(struct management *man)
+{
+    return management_would_hold(man) || (man->settings.flags & MF_QUERY_PASSWORDS);
+}
+
+/*
+ * If the hold flag is enabled, hibernate until a management client releases the hold.
+ * Return true if the caller should not sleep for an additional time interval.
+ */
+bool
+management_hold(struct management *man, int holdtime)
+{
+    if (management_would_hold(man))
+    {
+        volatile int signal_received = 0;
+        const bool standalone_disabled_save = man->persist.standalone_disabled;
+        struct gc_arena gc = gc_new();
+
+        man->persist.standalone_disabled = false; /* This is so M_CLIENT messages will be correctly passed through msg() */
+        man->persist.special_state_msg = NULL;
+        man->settings.mansig |= MANSIG_IGNORE_USR1_HUP;
+
+        man_wait_for_client_connection(man, &signal_received, 0, MWCC_HOLD_WAIT);
+
+        if (!signal_received)
+        {
+            struct buffer out = alloc_buf_gc(128, &gc);
+            buf_printf(&out, ">HOLD:Waiting for hold release:%d", holdtime);
+            man->persist.special_state_msg = BSTR(&out);
+            msg(M_CLIENT, "%s", man->persist.special_state_msg);
+
+            /* run command processing event loop until we get our username/password */
+            do
+            {
+                man_standalone_event_loop(man, &signal_received, 0);
+                if (!signal_received)
+                {
+                    man_check_for_signals(&signal_received);
+                }
+                if (signal_received)
+                {
+                    break;
+                }
+            } while (!man->persist.hold_release);
+        }
+
+        /* revert state */
+        man->persist.standalone_disabled = standalone_disabled_save;
+        man->persist.special_state_msg = NULL;
+        man->settings.mansig &= ~MANSIG_IGNORE_USR1_HUP;
+
+        gc_free(&gc);
+        return true;
+    }
+    return false;
+}
+
+/*
+ * struct command_line
+ */
+
+struct command_line *
+command_line_new(const int buf_len)
+{
+    struct command_line *cl;
+    ALLOC_OBJ_CLEAR(cl, struct command_line);
+    cl->buf = alloc_buf(buf_len);
+    cl->residual = alloc_buf(buf_len);
+    return cl;
+}
+
+void
+command_line_reset(struct command_line *cl)
+{
+    buf_clear(&cl->buf);
+    buf_clear(&cl->residual);
+}
+
+void
+command_line_free(struct command_line *cl)
+{
+    command_line_reset(cl);
+    free_buf(&cl->buf);
+    free_buf(&cl->residual);
+    free(cl);
+}
+
+void
+command_line_add(struct command_line *cl, const unsigned char *buf, const int len)
+{
+    int i;
+    for (i = 0; i < len; ++i)
+    {
+        if (buf[i] && char_class(buf[i], (CC_PRINT|CC_NEWLINE)))
+        {
+            if (!buf_write_u8(&cl->buf, buf[i]))
+            {
+                buf_clear(&cl->buf);
+            }
+        }
+    }
+}
+
+const char *
+command_line_get(struct command_line *cl)
+{
+    int i;
+    const char *ret = NULL;
+
+    i = buf_substring_len(&cl->buf, '\n');
+    if (i >= 0)
+    {
+        buf_copy_excess(&cl->residual, &cl->buf, i);
+        buf_chomp(&cl->buf);
+        ret = BSTR(&cl->buf);
+    }
+    return ret;
+}
+
+void
+command_line_next(struct command_line *cl)
+{
+    buf_clear(&cl->buf);
+    buf_copy(&cl->buf, &cl->residual);
+    buf_clear(&cl->residual);
+}
+
+/*
+ * struct log_entry
+ */
+
+const char *
+log_entry_print(const struct log_entry *e, unsigned int flags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(ERR_BUF_SIZE, gc);
+    if (flags & LOG_FATAL_NOTIFY)
+    {
+        buf_printf(&out, ">FATAL:");
+    }
+    if (flags & LOG_PRINT_LOG_PREFIX)
+    {
+        buf_printf(&out, ">LOG:");
+    }
+    if (flags & LOG_PRINT_ECHO_PREFIX)
+    {
+        buf_printf(&out, ">ECHO:");
+    }
+    if (flags & LOG_PRINT_STATE_PREFIX)
+    {
+        buf_printf(&out, ">STATE:");
+    }
+    if (flags & LOG_PRINT_INT_DATE)
+    {
+        buf_printf(&out, "%u,", (unsigned int)e->timestamp);
+    }
+    if (flags & LOG_PRINT_MSG_FLAGS)
+    {
+        buf_printf(&out, "%s,", msg_flags_string(e->u.msg_flags, gc));
+    }
+    if (flags & LOG_PRINT_STATE)
+    {
+        buf_printf(&out, "%s,", man_state_name(e->u.state));
+    }
+    if (flags & LOG_PRINT_INTVAL)
+    {
+        buf_printf(&out, "%d,", e->u.intval);
+    }
+    if (e->string)
+    {
+        buf_printf(&out, "%s", e->string);
+    }
+    if (flags & LOG_PRINT_LOCAL_IP)
+    {
+        buf_printf(&out, ",%s", print_in_addr_t(e->local_ip, IA_EMPTY_IF_UNDEF, gc));
+    }
+    if (flags & LOG_PRINT_REMOTE_IP)
+    {
+        buf_printf(&out, ",%s", (!addr_defined(&e->remote_sock) ? "," :
+                                 print_sockaddr_ex(&e->remote_sock.addr.sa, ",", PS_DONT_SHOW_FAMILY|PS_SHOW_PORT, gc)));
+        buf_printf(&out, ",%s", (!addr_defined(&e->local_sock) ? "," :
+                                 print_sockaddr_ex(&e->local_sock.addr.sa, ",", PS_DONT_SHOW_FAMILY|PS_SHOW_PORT, gc)));
+    }
+    if (flags & LOG_PRINT_LOCAL_IP && !IN6_IS_ADDR_UNSPECIFIED(&e->local_ip6))
+    {
+        buf_printf(&out, ",%s", print_in6_addr(e->local_ip6, IA_EMPTY_IF_UNDEF, gc));
+    }
+    if (flags & LOG_ECHO_TO_LOG)
+    {
+        msg(D_MANAGEMENT, "MANAGEMENT: %s", BSTR(&out));
+    }
+    if (flags & LOG_PRINT_CRLF)
+    {
+        buf_printf(&out, "\r\n");
+    }
+    return BSTR(&out);
+}
+
+static void
+log_entry_free_contents(struct log_entry *e)
+{
+    if (e->string)
+    {
+        free((char *)e->string);
+    }
+    CLEAR(*e);
+}
+
+/*
+ * struct log_history
+ */
+
+static inline int
+log_index(const struct log_history *h, int i)
+{
+    return modulo_add(h->base, i, h->capacity);
+}
+
+static void
+log_history_obj_init(struct log_history *h, int capacity)
+{
+    CLEAR(*h);
+    h->capacity = capacity;
+    ALLOC_ARRAY_CLEAR(h->array, struct log_entry, capacity);
+}
+
+struct log_history *
+log_history_init(const int capacity)
+{
+    struct log_history *h;
+    ASSERT(capacity > 0);
+    ALLOC_OBJ(h, struct log_history);
+    log_history_obj_init(h, capacity);
+    return h;
+}
+
+static void
+log_history_free_contents(struct log_history *h)
+{
+    int i;
+    for (i = 0; i < h->size; ++i)
+    {
+        log_entry_free_contents(&h->array[log_index(h, i)]);
+    }
+    free(h->array);
+}
+
+void
+log_history_close(struct log_history *h)
+{
+    log_history_free_contents(h);
+    free(h);
+}
+
+void
+log_history_add(struct log_history *h, const struct log_entry *le)
+{
+    struct log_entry *e;
+    ASSERT(h->size >= 0 && h->size <= h->capacity);
+    if (h->size == h->capacity)
+    {
+        e = &h->array[h->base];
+        log_entry_free_contents(e);
+        h->base = log_index(h, 1);
+    }
+    else
+    {
+        e = &h->array[log_index(h, h->size)];
+        ++h->size;
+    }
+
+    *e = *le;
+    e->string = string_alloc(le->string, NULL);
+}
+
+void
+log_history_resize(struct log_history *h, const int capacity)
+{
+    if (capacity != h->capacity)
+    {
+        struct log_history newlog;
+        int i;
+
+        ASSERT(capacity > 0);
+        log_history_obj_init(&newlog, capacity);
+
+        for (i = 0; i < h->size; ++i)
+        {
+            log_history_add(&newlog, &h->array[log_index(h, i)]);
+        }
+
+        log_history_free_contents(h);
+        *h = newlog;
+    }
+}
+
+const struct log_entry *
+log_history_ref(const struct log_history *h, const int index)
+{
+    if (index >= 0 && index < h->size)
+    {
+        return &h->array[log_index(h, (h->size - 1) - index)];
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+void
+management_sleep(const int n)
+{
+    if (management)
+    {
+        management_event_loop_n_seconds(management, n);
+    }
+    else
+    {
+        sleep(n);
+    }
+}
+
+#else  /* ifdef ENABLE_MANAGEMENT */
+
+void
+management_sleep(const int n)
+{
+    sleep(n);
+}
+
+#endif /* ENABLE_MANAGEMENT */
diff --git a/src/openvpn/manage.h b/src/openvpn/manage.h
new file mode 100644
index 0000000..f286754
--- /dev/null
+++ b/src/openvpn/manage.h
@@ -0,0 +1,615 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MANAGE_H
+#define MANAGE_H
+
+#ifdef ENABLE_MANAGEMENT
+
+#include "misc.h"
+#include "event.h"
+#include "socket.h"
+#include "mroute.h"
+
+#define MANAGEMENT_VERSION                      1
+#define MANAGEMENT_N_PASSWORD_RETRIES           3
+#define MANAGEMENT_LOG_HISTORY_INITIAL_SIZE   100
+#define MANAGEMENT_ECHO_BUFFER_SIZE           100
+#define MANAGEMENT_STATE_BUFFER_SIZE          100
+
+/*
+ * Management-interface-based deferred authentication
+ */
+#ifdef MANAGEMENT_DEF_AUTH
+struct man_def_auth_context {
+    unsigned long cid;
+
+#define DAF_CONNECTION_ESTABLISHED (1<<0)
+#define DAF_CONNECTION_CLOSED      (1<<1)
+#define DAF_INITIAL_AUTH           (1<<2)
+    unsigned int flags;
+
+    unsigned int mda_key_id_counter;
+
+    time_t bytecount_last_update;
+};
+#endif
+
+/*
+ * Manage build-up of command line
+ */
+struct command_line
+{
+    struct buffer buf;
+    struct buffer residual;
+};
+
+struct command_line *command_line_new(const int buf_len);
+
+void command_line_free(struct command_line *cl);
+
+void command_line_add(struct command_line *cl, const unsigned char *buf, const int len);
+
+const char *command_line_get(struct command_line *cl);
+
+void command_line_reset(struct command_line *cl);
+
+void command_line_next(struct command_line *cl);
+
+/*
+ * Manage log file history
+ */
+
+union log_entry_union {
+    unsigned int msg_flags;
+    int state;
+    int intval;
+};
+
+struct log_entry
+{
+    time_t timestamp;
+    const char *string;
+    in_addr_t local_ip;
+    struct in6_addr local_ip6;
+    struct openvpn_sockaddr local_sock;
+    struct openvpn_sockaddr remote_sock;
+    union log_entry_union u;
+};
+
+#define LOG_PRINT_LOG_PREFIX   (1<<0)
+#define LOG_PRINT_ECHO_PREFIX  (1<<1)
+#define LOG_PRINT_STATE_PREFIX (1<<2)
+
+#define LOG_PRINT_INT_DATE     (1<<3)
+#define LOG_PRINT_MSG_FLAGS    (1<<4)
+#define LOG_PRINT_STATE        (1<<5)
+#define LOG_PRINT_LOCAL_IP     (1<<6)
+
+#define LOG_PRINT_CRLF         (1<<7)
+#define LOG_FATAL_NOTIFY       (1<<8)
+
+#define LOG_PRINT_INTVAL       (1<<9)
+
+#define LOG_PRINT_REMOTE_IP    (1<<10)
+
+#define LOG_ECHO_TO_LOG        (1<<11)
+
+const char *log_entry_print(const struct log_entry *e, unsigned int flags, struct gc_arena *gc);
+
+struct log_history
+{
+    int base;
+    int size;
+    int capacity;
+    struct log_entry *array;
+};
+
+struct log_history *log_history_init(const int capacity);
+
+void log_history_close(struct log_history *h);
+
+void log_history_add(struct log_history *h, const struct log_entry *le);
+
+void log_history_resize(struct log_history *h, const int capacity);
+
+const struct log_entry *log_history_ref(const struct log_history *h, const int index);
+
+static inline int
+log_history_size(const struct log_history *h)
+{
+    return h->size;
+}
+
+static inline int
+log_history_capacity(const struct log_history *h)
+{
+    return h->capacity;
+}
+
+/*
+ * Callbacks for 'status' and 'kill' commands.
+ * Also for management-based deferred authentication and packet filter.
+ */
+struct management_callback
+{
+    void *arg;
+
+#define MCF_SERVER (1<<0)  /* is OpenVPN being run as a server? */
+    unsigned int flags;
+
+    void (*status) (void *arg, const int version, struct status_output *so);
+    void (*show_net) (void *arg, const int msglevel);
+    int (*kill_by_cn) (void *arg, const char *common_name);
+    int (*kill_by_addr) (void *arg, const in_addr_t addr, const int port);
+    void (*delete_event) (void *arg, event_t event);
+    int (*n_clients) (void *arg);
+#ifdef MANAGEMENT_DEF_AUTH
+    bool (*kill_by_cid)(void *arg, const unsigned long cid, const char *kill_msg);
+    bool (*client_auth) (void *arg,
+                         const unsigned long cid,
+                         const unsigned int mda_key_id,
+                         const bool auth,
+                         const char *reason,
+                         const char *client_reason,
+                         struct buffer_list *cc_config); /* ownership transferred */
+    char *(*get_peer_info) (void *arg, const unsigned long cid);
+#endif
+#ifdef MANAGEMENT_PF
+    bool (*client_pf)(void *arg,
+                      const unsigned long cid,
+                      struct buffer_list *pf_config);  /* ownership transferred */
+#endif
+    bool (*proxy_cmd)(void *arg, const char **p);
+    bool (*remote_cmd) (void *arg, const char **p);
+#ifdef TARGET_ANDROID
+    int (*network_change)(void *arg, bool samenetwork);
+#endif
+};
+
+/*
+ * Management object, split into three components:
+ *
+ * struct man_persist : Data elements which are persistent across
+ *                      man_connection open and close.
+ *
+ * struct man_settings : management parameters.
+ *
+ * struct man_connection : created on socket binding and listen,
+ *                         deleted on socket unbind, may
+ *                         handle multiple sequential client
+ *                         connections.
+ */
+
+struct man_persist {
+    bool defined;
+
+    struct log_history *log;
+    struct virtual_output vout;
+
+    bool standalone_disabled;
+    struct management_callback callback;
+
+    struct log_history *echo; /* saved --echo strings */
+    struct log_history *state;
+
+    bool hold_release;
+
+    const char *special_state_msg;
+
+    counter_type bytes_in;
+    counter_type bytes_out;
+};
+
+struct man_settings {
+    bool defined;
+    unsigned int flags; /* MF_x flags */
+    struct addrinfo *local;
+#if UNIX_SOCK_SUPPORT
+    struct sockaddr_un local_unix;
+#endif
+    bool management_over_tunnel;
+    struct user_pass up;
+    int log_history_cache;
+    int echo_buffer_size;
+    int state_buffer_size;
+    char *write_peer_info_file;
+    int client_uid;
+    int client_gid;
+
+/* flags for handling the management interface "signal" command */
+#define MANSIG_IGNORE_USR1_HUP  (1<<0)
+#define MANSIG_MAP_USR1_TO_HUP  (1<<1)
+#define MANSIG_MAP_USR1_TO_TERM (1<<2)
+    unsigned int mansig;
+};
+
+/* up_query modes */
+#define UP_QUERY_DISABLED  0
+#define UP_QUERY_USER_PASS 1
+#define UP_QUERY_PASS      2
+#define UP_QUERY_NEED_OK   3
+#define UP_QUERY_NEED_STR  4
+
+/* states */
+#define MS_INITIAL          0  /* all sockets are closed */
+#define MS_LISTEN           1  /* no client is connected */
+#define MS_CC_WAIT_READ     2  /* client is connected, waiting for read on socket */
+#define MS_CC_WAIT_WRITE    3  /* client is connected, waiting for ability to write to socket */
+
+struct man_connection {
+    int state;
+
+    socket_descriptor_t sd_top;
+    socket_descriptor_t sd_cli;
+    struct openvpn_sockaddr remote;
+
+#ifdef _WIN32
+    struct net_event_win32 ne32;
+#endif
+
+    bool halt;
+    bool password_verified;
+    int password_tries;
+
+    struct command_line *in;
+    struct buffer_list *out;
+
+#ifdef MANAGEMENT_IN_EXTRA
+#define IEC_UNDEF       0
+#define IEC_CLIENT_AUTH 1
+#define IEC_CLIENT_PF   2
+#define IEC_RSA_SIGN    3
+#define IEC_CERTIFICATE 4
+    int in_extra_cmd;
+    struct buffer_list *in_extra;
+#ifdef MANAGEMENT_DEF_AUTH
+    unsigned long in_extra_cid;
+    unsigned int in_extra_kid;
+#endif
+#ifdef MANAGMENT_EXTERNAL_KEY
+#define EKS_UNDEF   0
+#define EKS_SOLICIT 1
+#define EKS_INPUT   2
+#define EKS_READY   3
+    int ext_key_state;
+    struct buffer_list *ext_key_input;
+    int ext_cert_state;
+    struct buffer_list *ext_cert_input;
+#endif
+#endif /* ifdef MANAGEMENT_IN_EXTRA */
+    struct event_set *es;
+    int env_filter_level;
+
+    bool state_realtime;
+    bool log_realtime;
+    bool echo_realtime;
+    int bytecount_update_seconds;
+    time_t bytecount_last_update;
+
+    const char *up_query_type;
+    int up_query_mode;
+    struct user_pass up_query;
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+    struct buffer_list *rsa_sig;
+#endif
+#ifdef TARGET_ANDROID
+    int fdtosend;
+    int lastfdreceived;
+#endif
+};
+
+struct management
+{
+    struct man_persist persist;
+    struct man_settings settings;
+    struct man_connection connection;
+};
+
+extern struct management *management;
+
+struct user_pass;
+
+struct management *management_init(void);
+
+/* management_open flags */
+#define MF_SERVER            (1<<0)
+#define MF_QUERY_PASSWORDS   (1<<1)
+#define MF_HOLD              (1<<2)
+#define MF_SIGNAL            (1<<3)
+#define MF_FORGET_DISCONNECT (1<<4)
+#define MF_CONNECT_AS_CLIENT (1<<5)
+#ifdef MANAGEMENT_DEF_AUTH
+#define MF_CLIENT_AUTH       (1<<6)
+#endif
+#ifdef MANAGEMENT_PF
+#define MF_CLIENT_PF         (1<<7)
+#endif
+#define MF_UNIX_SOCK       (1<<8)
+#ifdef MANAGMENT_EXTERNAL_KEY
+#define MF_EXTERNAL_KEY    (1<<9)
+#endif
+#define MF_UP_DOWN          (1<<10)
+#define MF_QUERY_REMOTE     (1<<11)
+#define MF_QUERY_PROXY      (1<<12)
+#define MF_EXTERNAL_CERT    (1<<13)
+
+bool management_open(struct management *man,
+                     const char *addr,
+                     const char *port,
+                     const char *pass_file,
+                     const char *client_user,
+                     const char *client_group,
+                     const int log_history_cache,
+                     const int echo_buffer_size,
+                     const int state_buffer_size,
+                     const char *write_peer_info_file,
+                     const int remap_sigusr1,
+                     const unsigned int flags);
+
+void management_close(struct management *man);
+
+void management_post_tunnel_open(struct management *man, const in_addr_t tun_local_ip);
+
+void management_pre_tunnel_close(struct management *man);
+
+void management_socket_set(struct management *man,
+                           struct event_set *es,
+                           void *arg,
+                           unsigned int *persistent);
+
+void management_io(struct management *man);
+
+void management_set_callback(struct management *man,
+                             const struct management_callback *cb);
+
+void management_clear_callback(struct management *man);
+
+bool management_query_user_pass(struct management *man,
+                                struct user_pass *up,
+                                const char *type,
+                                const unsigned int flags,
+                                const char *static_challenge);
+
+#ifdef TARGET_ANDROID
+bool management_android_control(struct management *man, const char *command, const char *msg);
+
+#define ANDROID_KEEP_OLD_TUN 1
+#define ANDROID_OPEN_AFTER_CLOSE 2
+#define ANDROID_OPEN_BEFORE_CLOSE 3
+int managment_android_persisttun_action(struct management *man);
+
+#endif
+
+bool management_should_daemonize(struct management *man);
+
+bool management_would_hold(struct management *man);
+
+bool management_hold(struct management *man, int holdtime);
+
+void management_event_loop_n_seconds(struct management *man, int sec);
+
+void management_up_down(struct management *man, const char *updown, const struct env_set *es);
+
+void management_notify(struct management *man, const char *severity, const char *type, const char *text);
+
+void management_notify_generic(struct management *man, const char *str);
+
+#ifdef MANAGEMENT_DEF_AUTH
+void management_notify_client_needing_auth(struct management *management,
+                                           const unsigned int auth_id,
+                                           struct man_def_auth_context *mdac,
+                                           const struct env_set *es);
+
+void management_connection_established(struct management *management,
+                                       struct man_def_auth_context *mdac,
+                                       const struct env_set *es);
+
+void management_notify_client_close(struct management *management,
+                                    struct man_def_auth_context *mdac,
+                                    const struct env_set *es);
+
+void management_learn_addr(struct management *management,
+                           struct man_def_auth_context *mdac,
+                           const struct mroute_addr *addr,
+                           const bool primary);
+
+#endif
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+char *management_query_rsa_sig(struct management *man, const char *b64_data);
+
+char *management_query_cert(struct management *man, const char *cert_name);
+
+#endif
+
+static inline bool
+management_connected(const struct management *man)
+{
+    return man->connection.state == MS_CC_WAIT_READ || man->connection.state == MS_CC_WAIT_WRITE;
+}
+
+static inline bool
+management_query_user_pass_enabled(const struct management *man)
+{
+    return BOOL_CAST(man->settings.flags & MF_QUERY_PASSWORDS);
+}
+
+static inline bool
+management_query_remote_enabled(const struct management *man)
+{
+    return BOOL_CAST(man->settings.flags & MF_QUERY_REMOTE);
+}
+
+static inline bool
+management_query_proxy_enabled(const struct management *man)
+{
+    return BOOL_CAST(man->settings.flags & MF_QUERY_PROXY);
+}
+
+#ifdef MANAGEMENT_PF
+static inline bool
+management_enable_pf(const struct management *man)
+{
+    return man && BOOL_CAST(man->settings.flags & MF_CLIENT_PF);
+}
+#endif
+
+#ifdef MANAGEMENT_DEF_AUTH
+static inline bool
+management_enable_def_auth(const struct management *man)
+{
+    return man && BOOL_CAST(man->settings.flags & MF_CLIENT_AUTH);
+}
+#endif
+
+/*
+ * OpenVPN tells the management layer what state it's in
+ */
+
+/* client/server states */
+#define OPENVPN_STATE_INITIAL       0  /* Initial, undefined state */
+#define OPENVPN_STATE_CONNECTING    1  /* Management interface has been initialized */
+#define OPENVPN_STATE_ASSIGN_IP     2  /* Assigning IP address to virtual network interface */
+#define OPENVPN_STATE_ADD_ROUTES    3  /* Adding routes to system */
+#define OPENVPN_STATE_CONNECTED     4  /* Initialization sequence completed */
+#define OPENVPN_STATE_RECONNECTING  5  /* Restart */
+#define OPENVPN_STATE_EXITING       6  /* Exit */
+
+/* client-only states */
+#define OPENVPN_STATE_WAIT          7  /* Waiting for initial response from server */
+#define OPENVPN_STATE_AUTH          8  /* Authenticating with server */
+#define OPENVPN_STATE_GET_CONFIG    9  /* Downloading configuration from server */
+#define OPENVPN_STATE_RESOLVE       10 /* DNS lookup */
+#define OPENVPN_STATE_TCP_CONNECT   11 /* Connecting to TCP server */
+
+#define OPENVPN_STATE_CLIENT_BASE   7  /* Base index of client-only states */
+
+void management_set_state(struct management *man,
+                          const int state,
+                          const char *detail,
+                          const in_addr_t *tun_local_ip,
+                          const struct in6_addr *tun_local_ip6,
+                          const struct openvpn_sockaddr *local_addr,
+                          const struct openvpn_sockaddr *remote_addr);
+
+/*
+ * The management object keeps track of OpenVPN --echo
+ * parameters.
+ */
+void management_echo(struct management *man, const char *string, const bool pull);
+
+/*
+ * OpenVPN calls here to indicate a password failure
+ */
+
+void management_auth_failure(struct management *man, const char *type, const char *reason);
+
+/*
+ * Echo an authentication token to management interface
+ */
+void management_auth_token(struct management *man, const char *token);
+
+/*
+ * These functions drive the bytecount in/out counters.
+ */
+
+void man_bytecount_output_client(struct management *man);
+
+static inline void
+man_bytecount_possible_output_client(struct management *man)
+{
+    if (man->connection.bytecount_update_seconds > 0
+        && now >= man->connection.bytecount_last_update
+        + man->connection.bytecount_update_seconds)
+    {
+        man_bytecount_output_client(man);
+    }
+}
+
+static inline void
+management_bytes_out_client(struct management *man, const int size)
+{
+    man->persist.bytes_out += size;
+    man_bytecount_possible_output_client(man);
+}
+
+static inline void
+management_bytes_in_client(struct management *man, const int size)
+{
+    man->persist.bytes_in += size;
+    man_bytecount_possible_output_client(man);
+}
+
+static inline void
+management_bytes_out(struct management *man, const int size)
+{
+    if (!(man->persist.callback.flags & MCF_SERVER))
+    {
+        management_bytes_out_client(man, size);
+    }
+}
+
+static inline void
+management_bytes_in(struct management *man, const int size)
+{
+    if (!(man->persist.callback.flags & MCF_SERVER))
+    {
+        management_bytes_in_client(man, size);
+    }
+}
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+static inline void
+management_bytes_server(struct management *man,
+                        const counter_type *bytes_in_total,
+                        const counter_type *bytes_out_total,
+                        struct man_def_auth_context *mdac)
+{
+    void man_bytecount_output_server(struct management *man,
+                                     const counter_type *bytes_in_total,
+                                     const counter_type *bytes_out_total,
+                                     struct man_def_auth_context *mdac);
+
+    if (man->connection.bytecount_update_seconds > 0
+        && now >= mdac->bytecount_last_update + man->connection.bytecount_update_seconds
+        && (mdac->flags & (DAF_CONNECTION_ESTABLISHED|DAF_CONNECTION_CLOSED)) == DAF_CONNECTION_ESTABLISHED)
+    {
+        man_bytecount_output_server(man, bytes_in_total, bytes_out_total, mdac);
+    }
+}
+
+#endif /* MANAGEMENT_DEF_AUTH */
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+/**
+ * A sleep function that services the management layer for n seconds rather
+ * than doing nothing.
+ */
+void management_sleep(const int n);
+
+#endif /* ifndef MANAGE_H */
diff --git a/src/openvpn/mbuf.c b/src/openvpn/mbuf.c
new file mode 100644
index 0000000..87faff0
--- /dev/null
+++ b/src/openvpn/mbuf.c
@@ -0,0 +1,180 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP
+
+#include "buffer.h"
+#include "error.h"
+#include "integer.h"
+#include "misc.h"
+#include "mbuf.h"
+
+#include "memdbg.h"
+
+struct mbuf_set *
+mbuf_init(unsigned int size)
+{
+    struct mbuf_set *ret;
+    ALLOC_OBJ_CLEAR(ret, struct mbuf_set);
+    ret->capacity = adjust_power_of_2(size);
+    ALLOC_ARRAY(ret->array, struct mbuf_item, ret->capacity);
+    return ret;
+}
+
+void
+mbuf_free(struct mbuf_set *ms)
+{
+    if (ms)
+    {
+        int i;
+        for (i = 0; i < (int) ms->len; ++i)
+        {
+            struct mbuf_item *item = &ms->array[MBUF_INDEX(ms->head, i, ms->capacity)];
+            mbuf_free_buf(item->buffer);
+        }
+        free(ms->array);
+        free(ms);
+    }
+}
+
+struct mbuf_buffer *
+mbuf_alloc_buf(const struct buffer *buf)
+{
+    struct mbuf_buffer *ret;
+    ALLOC_OBJ(ret, struct mbuf_buffer);
+    ret->buf = clone_buf(buf);
+    ret->refcount = 1;
+    ret->flags = 0;
+    return ret;
+}
+
+void
+mbuf_free_buf(struct mbuf_buffer *mb)
+{
+    if (mb)
+    {
+        if (--mb->refcount <= 0)
+        {
+            free_buf(&mb->buf);
+            free(mb);
+        }
+    }
+}
+
+void
+mbuf_add_item(struct mbuf_set *ms, const struct mbuf_item *item)
+{
+    ASSERT(ms);
+    if (ms->len == ms->capacity)
+    {
+        struct mbuf_item rm;
+        ASSERT(mbuf_extract_item(ms, &rm));
+        mbuf_free_buf(rm.buffer);
+        msg(D_MULTI_DROPPED, "MBUF: mbuf packet dropped");
+    }
+
+    ASSERT(ms->len < ms->capacity);
+
+    ms->array[MBUF_INDEX(ms->head, ms->len, ms->capacity)] = *item;
+    if (++ms->len > ms->max_queued)
+    {
+        ms->max_queued = ms->len;
+    }
+    ++item->buffer->refcount;
+}
+
+bool
+mbuf_extract_item(struct mbuf_set *ms, struct mbuf_item *item)
+{
+    bool ret = false;
+    if (ms)
+    {
+        while (ms->len)
+        {
+            *item = ms->array[ms->head];
+            ms->head = MBUF_INDEX(ms->head, 1, ms->capacity);
+            --ms->len;
+            if (item->instance) /* ignore dereferenced instances */
+            {
+                ret = true;
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+struct multi_instance *
+mbuf_peek_dowork(struct mbuf_set *ms)
+{
+    struct multi_instance *ret = NULL;
+    if (ms)
+    {
+        int i;
+        for (i = 0; i < (int) ms->len; ++i)
+        {
+            struct mbuf_item *item = &ms->array[MBUF_INDEX(ms->head, i, ms->capacity)];
+            if (item->instance)
+            {
+                ret = item->instance;
+                break;
+            }
+        }
+    }
+    return ret;
+}
+
+void
+mbuf_dereference_instance(struct mbuf_set *ms, struct multi_instance *mi)
+{
+    if (ms)
+    {
+        int i;
+        for (i = 0; i < (int) ms->len; ++i)
+        {
+            struct mbuf_item *item = &ms->array[MBUF_INDEX(ms->head, i, ms->capacity)];
+            if (item->instance == mi)
+            {
+                mbuf_free_buf(item->buffer);
+                item->buffer = NULL;
+                item->instance = NULL;
+                msg(D_MBUF, "MBUF: dereferenced queued packet");
+            }
+        }
+    }
+}
+
+#else  /* if P2MP */
+static void
+dummy(void)
+{
+}
+#endif /* P2MP */
diff --git a/src/openvpn/mbuf.h b/src/openvpn/mbuf.h
new file mode 100644
index 0000000..4912c95
--- /dev/null
+++ b/src/openvpn/mbuf.h
@@ -0,0 +1,115 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MBUF_H
+#define MBUF_H
+
+/*
+ * Handle both multicast and broadcast functions.
+ */
+
+#if P2MP
+
+/* define this to enable special test mode */
+/*#define MBUF_TEST*/
+
+#include "basic.h"
+#include "buffer.h"
+
+struct multi_instance;
+
+#define MBUF_INDEX(head, offset, size) (((head) + (offset)) & ((size)-1))
+
+struct mbuf_buffer
+{
+    struct buffer buf;
+    int refcount;
+
+#define MF_UNICAST (1<<0)
+    unsigned int flags;
+};
+
+struct mbuf_item
+{
+    struct mbuf_buffer *buffer;
+    struct multi_instance *instance;
+};
+
+struct mbuf_set
+{
+    unsigned int head;
+    unsigned int len;
+    unsigned int capacity;
+    unsigned int max_queued;
+    struct mbuf_item *array;
+};
+
+struct mbuf_set *mbuf_init(unsigned int size);
+
+void mbuf_free(struct mbuf_set *ms);
+
+struct mbuf_buffer *mbuf_alloc_buf(const struct buffer *buf);
+
+void mbuf_free_buf(struct mbuf_buffer *mb);
+
+void mbuf_add_item(struct mbuf_set *ms, const struct mbuf_item *item);
+
+bool mbuf_extract_item(struct mbuf_set *ms, struct mbuf_item *item);
+
+void mbuf_dereference_instance(struct mbuf_set *ms, struct multi_instance *mi);
+
+static inline bool
+mbuf_defined(const struct mbuf_set *ms)
+{
+    return ms && ms->len;
+}
+
+static inline unsigned int
+mbuf_len(const struct mbuf_set *ms)
+{
+    return ms->len;
+}
+
+static inline int
+mbuf_maximum_queued(const struct mbuf_set *ms)
+{
+    return (int) ms->max_queued;
+}
+
+static inline struct multi_instance *
+mbuf_peek(struct mbuf_set *ms)
+{
+    struct multi_instance *mbuf_peek_dowork(struct mbuf_set *ms);
+
+    if (mbuf_defined(ms))
+    {
+        return mbuf_peek_dowork(ms);
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+#endif /* if P2MP */
+#endif /* ifndef MBUF_H */
diff --git a/src/openvpn/memdbg.h b/src/openvpn/memdbg.h
new file mode 100644
index 0000000..70c6365
--- /dev/null
+++ b/src/openvpn/memdbg.h
@@ -0,0 +1,113 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MEMDBG_H
+#define MEMDBG_H
+
+/*
+ * Valgrind debugging support.
+ *
+ * Valgrind is a great tool for debugging memory issues,
+ * though it seems to generate a lot of warnings in OpenSSL
+ * about uninitialized data. To silence these warnings,
+ * I've put together a suppressions file
+ * in debug/valgrind-suppress.
+ *
+ * Also, grep for VALGRIND_MAKE_READABLE in the OpenVPN source.
+ * Because valgrind thinks that some of the data passed from
+ * OpenSSL back to OpenVPN is tainted due to being sourced
+ * from uninitialized data, we need to untaint it before use --
+ * otherwise we will get a lot of useless warnings.
+ *
+ *   valgrind --tool=memcheck --error-limit=no --suppressions=debug/valgrind-suppress --gen-suppressions=yes ./openvpn ...
+ */
+
+#ifdef USE_VALGRIND
+
+#include "valgrind/memcheck.h"
+
+#define VALGRIND_MAKE_READABLE(addr, len)
+
+#else  /* ifdef USE_VALGRIND */
+
+#define VALGRIND_MAKE_READABLE(addr, len)
+
+#endif
+
+#ifdef DMALLOC /* see ./configure options to enable */
+
+/*
+ * See ./configure options to enable dmalloc
+ * support for memory leak checking.
+ *
+ * The dmalloc package can be downloaded from:
+ *
+ *     http://dmalloc.com/
+ *
+ * When dmalloc is installed and enabled,
+ * use this command prior to running openvpn:
+ *
+ *    dmalloc -l dlog -i 100 low -p log-unknown
+ *
+ * Also, put this in your .bashrc file:
+ *
+ *    function dmalloc { eval `command dmalloc -b $*`; }
+ *
+ * Or take a more low-level approach:
+ *
+ *    export DMALLOC_OPTIONS="debug=0x4e48503,inter=100,log=dlog"
+ *
+ *  NOTE: When building dmalloc you need to add something
+ *  like this to dmalloc's settings.h -- it will allocate a static
+ *  buffer to be used as the malloc arena:
+ *
+ *  #define INTERNAL_MEMORY_SPACE (1024 * 1024 * 50)
+ */
+
+#include "dmalloc.h"
+
+#define openvpn_dmalloc(file, line, size) dmalloc_malloc((file), (line), (size), DMALLOC_FUNC_MALLOC, 0, 0)
+
+/*
+ * This #define will put the line number of the log
+ * file position where leaked memory was allocated instead
+ * of the source code file and line number.  Make sure
+ * to increase the size of dmalloc's info tables,
+ * (MEMORY_TABLE_SIZE in settings.h)
+ * otherwise it might get overwhelmed by the large
+ * number of unique file/line combinations.
+ */
+#if 0
+#undef malloc
+#define malloc(size) openvpn_dmalloc("logfile", x_msg_line_num, (size))
+#endif
+
+#endif /* DMALLOC */
+
+/*
+ * Force buffers to be zeroed after allocation.
+ * For debugging only.
+ */
+/*#define ZERO_BUFFER_ON_ALLOC*/
+
+#endif /* MEMDBG_H */
diff --git a/src/openvpn/misc.c b/src/openvpn/misc.c
new file mode 100644
index 0000000..9c5e96e
--- /dev/null
+++ b/src/openvpn/misc.c
@@ -0,0 +1,1670 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2014-2015 David Sommerseth <davids@redhat.com>
+ *  Copyright (C) 2016-2018 David Sommerseth <davids@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "misc.h"
+#include "base64.h"
+#include "tun.h"
+#include "error.h"
+#include "otime.h"
+#include "plugin.h"
+#include "options.h"
+#include "manage.h"
+#include "crypto.h"
+#include "route.h"
+#include "console.h"
+#include "win32.h"
+
+#include "memdbg.h"
+
+#ifdef ENABLE_IPROUTE
+const char *iproute_path = IPROUTE_PATH; /* GLOBAL */
+#endif
+
+/* contains an SSEC_x value defined in misc.h */
+int script_security = SSEC_BUILT_IN; /* GLOBAL */
+
+/*
+ * Set standard file descriptors to /dev/null
+ */
+void
+set_std_files_to_null(bool stdin_only)
+{
+#if defined(HAVE_DUP) && defined(HAVE_DUP2)
+    int fd;
+    if ((fd = open("/dev/null", O_RDWR, 0)) != -1)
+    {
+        dup2(fd, 0);
+        if (!stdin_only)
+        {
+            dup2(fd, 1);
+            dup2(fd, 2);
+        }
+        if (fd > 2)
+        {
+            close(fd);
+        }
+    }
+#endif
+}
+
+/*
+ *  dup inetd/xinetd socket descriptor and save
+ */
+
+int inetd_socket_descriptor = SOCKET_UNDEFINED; /* GLOBAL */
+
+void
+save_inetd_socket_descriptor(void)
+{
+    inetd_socket_descriptor = INETD_SOCKET_DESCRIPTOR;
+#if defined(HAVE_DUP) && defined(HAVE_DUP2)
+    /* use handle passed by inetd/xinetd */
+    if ((inetd_socket_descriptor = dup(INETD_SOCKET_DESCRIPTOR)) < 0)
+    {
+        msg(M_ERR, "INETD_SOCKET_DESCRIPTOR dup(%d) failed", INETD_SOCKET_DESCRIPTOR);
+    }
+    set_std_files_to_null(true);
+#endif
+}
+
+/*
+ * Generate an error message based on the status code returned by openvpn_execve().
+ */
+const char *
+system_error_message(int stat, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    switch (stat)
+    {
+        case OPENVPN_EXECVE_NOT_ALLOWED:
+            buf_printf(&out, "disallowed by script-security setting");
+            break;
+
+#ifdef _WIN32
+        case OPENVPN_EXECVE_ERROR:
+            buf_printf(&out, "external program did not execute -- ");
+        /* fall through */
+
+        default:
+            buf_printf(&out, "returned error code %d", stat);
+            break;
+#else  /* ifdef _WIN32 */
+
+        case OPENVPN_EXECVE_ERROR:
+            buf_printf(&out, "external program fork failed");
+            break;
+
+        default:
+            if (!WIFEXITED(stat))
+            {
+                buf_printf(&out, "external program did not exit normally");
+            }
+            else
+            {
+                const int cmd_ret = WEXITSTATUS(stat);
+                if (!cmd_ret)
+                {
+                    buf_printf(&out, "external program exited normally");
+                }
+                else if (cmd_ret == OPENVPN_EXECVE_FAILURE)
+                {
+                    buf_printf(&out, "could not execute external program");
+                }
+                else
+                {
+                    buf_printf(&out, "external program exited with error status: %d", cmd_ret);
+                }
+            }
+            break;
+#endif /* ifdef _WIN32 */
+    }
+    return (const char *)out.data;
+}
+
+/*
+ * Wrapper around openvpn_execve
+ */
+bool
+openvpn_execve_check(const struct argv *a, const struct env_set *es, const unsigned int flags, const char *error_message)
+{
+    struct gc_arena gc = gc_new();
+    const int stat = openvpn_execve(a, es, flags);
+    int ret = false;
+
+    if (platform_system_ok(stat))
+    {
+        ret = true;
+    }
+    else
+    {
+        if (error_message)
+        {
+            msg(((flags & S_FATAL) ? M_FATAL : M_WARN), "%s: %s",
+                error_message,
+                system_error_message(stat, &gc));
+        }
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+bool
+openvpn_execve_allowed(const unsigned int flags)
+{
+    if (flags & S_SCRIPT)
+    {
+        return script_security >= SSEC_SCRIPTS;
+    }
+    else
+    {
+        return script_security >= SSEC_BUILT_IN;
+    }
+}
+
+
+#ifndef _WIN32
+/*
+ * Run execve() inside a fork().  Designed to replicate the semantics of system() but
+ * in a safer way that doesn't require the invocation of a shell or the risks
+ * assocated with formatting and parsing a command line.
+ * Returns the exit status of child, OPENVPN_EXECVE_NOT_ALLOWED if openvpn_execve_allowed()
+ * returns false, or OPENVPN_EXECVE_ERROR on other errors.
+ */
+int
+openvpn_execve(const struct argv *a, const struct env_set *es, const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    int ret = OPENVPN_EXECVE_ERROR;
+    static bool warn_shown = false;
+
+    if (a && a->argv[0])
+    {
+#if defined(ENABLE_FEATURE_EXECVE)
+        if (openvpn_execve_allowed(flags))
+        {
+            const char *cmd = a->argv[0];
+            char *const *argv = a->argv;
+            char *const *envp = (char *const *)make_env_array(es, true, &gc);
+            pid_t pid;
+
+            pid = fork();
+            if (pid == (pid_t)0) /* child side */
+            {
+                execve(cmd, argv, envp);
+                exit(OPENVPN_EXECVE_FAILURE);
+            }
+            else if (pid < (pid_t)0) /* fork failed */
+            {
+                msg(M_ERR, "openvpn_execve: unable to fork");
+            }
+            else /* parent side */
+            {
+                if (waitpid(pid, &ret, 0) != pid)
+                {
+                    ret = OPENVPN_EXECVE_ERROR;
+                }
+            }
+        }
+        else
+        {
+            ret = OPENVPN_EXECVE_NOT_ALLOWED;
+            if (!warn_shown && (script_security < SSEC_SCRIPTS))
+            {
+                msg(M_WARN, SCRIPT_SECURITY_WARNING);
+                warn_shown = true;
+            }
+        }
+#else  /* if defined(ENABLE_FEATURE_EXECVE) */
+        msg(M_WARN, "openvpn_execve: execve function not available");
+#endif /* if defined(ENABLE_FEATURE_EXECVE) */
+    }
+    else
+    {
+        msg(M_FATAL, "openvpn_execve: called with empty argv");
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+#endif /* ifndef _WIN32 */
+
+/*
+ * Run execve() inside a fork(), duping stdout.  Designed to replicate the semantics of popen() but
+ * in a safer way that doesn't require the invocation of a shell or the risks
+ * assocated with formatting and parsing a command line.
+ */
+int
+openvpn_popen(const struct argv *a,  const struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    int ret = -1;
+    static bool warn_shown = false;
+
+    if (a && a->argv[0])
+    {
+#if defined(ENABLE_FEATURE_EXECVE)
+        if (script_security >= SSEC_BUILT_IN)
+        {
+            const char *cmd = a->argv[0];
+            char *const *argv = a->argv;
+            char *const *envp = (char *const *)make_env_array(es, true, &gc);
+            pid_t pid;
+            int pipe_stdout[2];
+
+            if (pipe(pipe_stdout) == 0)
+            {
+                pid = fork();
+                if (pid == (pid_t)0)       /* child side */
+                {
+                    close(pipe_stdout[0]);         /* Close read end */
+                    dup2(pipe_stdout[1],1);
+                    execve(cmd, argv, envp);
+                    exit(OPENVPN_EXECVE_FAILURE);
+                }
+                else if (pid > (pid_t)0)       /* parent side */
+                {
+                    int status = 0;
+
+                    close(pipe_stdout[1]);        /* Close write end */
+                    waitpid(pid, &status, 0);
+                    ret = pipe_stdout[0];
+                }
+                else       /* fork failed */
+                {
+                    close(pipe_stdout[0]);
+                    close(pipe_stdout[1]);
+                    msg(M_ERR, "openvpn_popen: unable to fork %s", cmd);
+                }
+            }
+            else
+            {
+                msg(M_WARN, "openvpn_popen: unable to create stdout pipe for %s", cmd);
+                ret = -1;
+            }
+        }
+        else if (!warn_shown && (script_security < SSEC_SCRIPTS))
+        {
+            msg(M_WARN, SCRIPT_SECURITY_WARNING);
+            warn_shown = true;
+        }
+#else  /* if defined(ENABLE_FEATURE_EXECVE) */
+        msg(M_WARN, "openvpn_popen: execve function not available");
+#endif /* if defined(ENABLE_FEATURE_EXECVE) */
+    }
+    else
+    {
+        msg(M_FATAL, "openvpn_popen: called with empty argv");
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+
+
+/*
+ * Set environmental variable (int or string).
+ *
+ * On Posix, we use putenv for portability,
+ * and put up with its painful semantics
+ * that require all the support code below.
+ */
+
+/* General-purpose environmental variable set functions */
+
+static char *
+construct_name_value(const char *name, const char *value, struct gc_arena *gc)
+{
+    struct buffer out;
+
+    ASSERT(name);
+    if (!value)
+    {
+        value = "";
+    }
+    out = alloc_buf_gc(strlen(name) + strlen(value) + 2, gc);
+    buf_printf(&out, "%s=%s", name, value);
+    return BSTR(&out);
+}
+
+static bool
+env_string_equal(const char *s1, const char *s2)
+{
+    int c1, c2;
+    ASSERT(s1);
+    ASSERT(s2);
+
+    while (true)
+    {
+        c1 = *s1++;
+        c2 = *s2++;
+        if (c1 == '=')
+        {
+            c1 = 0;
+        }
+        if (c2 == '=')
+        {
+            c2 = 0;
+        }
+        if (!c1 && !c2)
+        {
+            return true;
+        }
+        if (c1 != c2)
+        {
+            break;
+        }
+    }
+    return false;
+}
+
+static bool
+remove_env_item(const char *str, const bool do_free, struct env_item **list)
+{
+    struct env_item *current, *prev;
+
+    ASSERT(str);
+    ASSERT(list);
+
+    for (current = *list, prev = NULL; current != NULL; current = current->next)
+    {
+        if (env_string_equal(current->string, str))
+        {
+            if (prev)
+            {
+                prev->next = current->next;
+            }
+            else
+            {
+                *list = current->next;
+            }
+            if (do_free)
+            {
+                secure_memzero(current->string, strlen(current->string));
+                free(current->string);
+                free(current);
+            }
+            return true;
+        }
+        prev = current;
+    }
+    return false;
+}
+
+static void
+add_env_item(char *str, const bool do_alloc, struct env_item **list, struct gc_arena *gc)
+{
+    struct env_item *item;
+
+    ASSERT(str);
+    ASSERT(list);
+
+    ALLOC_OBJ_GC(item, struct env_item, gc);
+    item->string = do_alloc ? string_alloc(str, gc) : str;
+    item->next = *list;
+    *list = item;
+}
+
+/* struct env_set functions */
+
+static bool
+env_set_del_nolock(struct env_set *es, const char *str)
+{
+    return remove_env_item(str, es->gc == NULL, &es->list);
+}
+
+static void
+env_set_add_nolock(struct env_set *es, const char *str)
+{
+    remove_env_item(str, es->gc == NULL, &es->list);
+    add_env_item((char *)str, true, &es->list, es->gc);
+}
+
+struct env_set *
+env_set_create(struct gc_arena *gc)
+{
+    struct env_set *es;
+    ALLOC_OBJ_CLEAR_GC(es, struct env_set, gc);
+    es->list = NULL;
+    es->gc = gc;
+    return es;
+}
+
+void
+env_set_destroy(struct env_set *es)
+{
+    if (es && es->gc == NULL)
+    {
+        struct env_item *e = es->list;
+        while (e)
+        {
+            struct env_item *next = e->next;
+            free(e->string);
+            free(e);
+            e = next;
+        }
+        free(es);
+    }
+}
+
+bool
+env_set_del(struct env_set *es, const char *str)
+{
+    bool ret;
+    ASSERT(es);
+    ASSERT(str);
+    ret = env_set_del_nolock(es, str);
+    return ret;
+}
+
+void
+env_set_add(struct env_set *es, const char *str)
+{
+    ASSERT(es);
+    ASSERT(str);
+    env_set_add_nolock(es, str);
+}
+
+const char *
+env_set_get(const struct env_set *es, const char *name)
+{
+    const struct env_item *item = es->list;
+    while (item && !env_string_equal(item->string, name))
+    {
+        item = item->next;
+    }
+    return item ? item->string : NULL;
+}
+
+void
+env_set_print(int msglevel, const struct env_set *es)
+{
+    if (check_debug_level(msglevel))
+    {
+        const struct env_item *e;
+        int i;
+
+        if (es)
+        {
+            e = es->list;
+            i = 0;
+
+            while (e)
+            {
+                if (env_safe_to_print(e->string))
+                {
+                    msg(msglevel, "ENV [%d] '%s'", i, e->string);
+                }
+                ++i;
+                e = e->next;
+            }
+        }
+    }
+}
+
+void
+env_set_inherit(struct env_set *es, const struct env_set *src)
+{
+    const struct env_item *e;
+
+    ASSERT(es);
+
+    if (src)
+    {
+        e = src->list;
+        while (e)
+        {
+            env_set_add_nolock(es, e->string);
+            e = e->next;
+        }
+    }
+}
+
+
+/* add/modify/delete environmental strings */
+
+void
+setenv_counter(struct env_set *es, const char *name, counter_type value)
+{
+    char buf[64];
+    openvpn_snprintf(buf, sizeof(buf), counter_format, value);
+    setenv_str(es, name, buf);
+}
+
+void
+setenv_int(struct env_set *es, const char *name, int value)
+{
+    char buf[64];
+    openvpn_snprintf(buf, sizeof(buf), "%d", value);
+    setenv_str(es, name, buf);
+}
+
+void
+setenv_unsigned(struct env_set *es, const char *name, unsigned int value)
+{
+    char buf[64];
+    openvpn_snprintf(buf, sizeof(buf), "%u", value);
+    setenv_str(es, name, buf);
+}
+
+void
+setenv_str(struct env_set *es, const char *name, const char *value)
+{
+    setenv_str_ex(es, name, value, CC_NAME, 0, 0, CC_PRINT, 0, 0);
+}
+
+void
+setenv_str_safe(struct env_set *es, const char *name, const char *value)
+{
+    uint8_t b[64];
+    struct buffer buf;
+    buf_set_write(&buf, b, sizeof(b));
+    if (buf_printf(&buf, "OPENVPN_%s", name))
+    {
+        setenv_str(es, BSTR(&buf), value);
+    }
+    else
+    {
+        msg(M_WARN, "setenv_str_safe: name overflow");
+    }
+}
+
+void
+setenv_str_incr(struct env_set *es, const char *name, const char *value)
+{
+    unsigned int counter = 1;
+    const size_t tmpname_len = strlen(name) + 5; /* 3 digits counter max */
+    char *tmpname = gc_malloc(tmpname_len, true, NULL);
+    strcpy(tmpname, name);
+    while (NULL != env_set_get(es, tmpname) && counter < 1000)
+    {
+        ASSERT(openvpn_snprintf(tmpname, tmpname_len, "%s_%u", name, counter));
+        counter++;
+    }
+    if (counter < 1000)
+    {
+        setenv_str(es, tmpname, value);
+    }
+    else
+    {
+        msg(D_TLS_DEBUG_MED, "Too many same-name env variables, ignoring: %s", name);
+    }
+    free(tmpname);
+}
+
+void
+setenv_del(struct env_set *es, const char *name)
+{
+    ASSERT(name);
+    setenv_str(es, name, NULL);
+}
+
+void
+setenv_str_ex(struct env_set *es,
+              const char *name,
+              const char *value,
+              const unsigned int name_include,
+              const unsigned int name_exclude,
+              const char name_replace,
+              const unsigned int value_include,
+              const unsigned int value_exclude,
+              const char value_replace)
+{
+    struct gc_arena gc = gc_new();
+    const char *name_tmp;
+    const char *val_tmp = NULL;
+
+    ASSERT(name && strlen(name) > 1);
+
+    name_tmp = string_mod_const(name, name_include, name_exclude, name_replace, &gc);
+
+    if (value)
+    {
+        val_tmp = string_mod_const(value, value_include, value_exclude, value_replace, &gc);
+    }
+
+    ASSERT(es);
+
+    if (val_tmp)
+    {
+        const char *str = construct_name_value(name_tmp, val_tmp, &gc);
+        env_set_add(es, str);
+#if DEBUG_VERBOSE_SETENV
+        msg(M_INFO, "SETENV_ES '%s'", str);
+#endif
+    }
+    else
+    {
+        env_set_del(es, name_tmp);
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Setenv functions that append an integer index to the name
+ */
+static const char *
+setenv_format_indexed_name(const char *name, const int i, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(strlen(name) + 16, gc);
+    if (i >= 0)
+    {
+        buf_printf(&out, "%s_%d", name, i);
+    }
+    else
+    {
+        buf_printf(&out, "%s", name);
+    }
+    return BSTR(&out);
+}
+
+void
+setenv_int_i(struct env_set *es, const char *name, const int value, const int i)
+{
+    struct gc_arena gc = gc_new();
+    const char *name_str = setenv_format_indexed_name(name, i, &gc);
+    setenv_int(es, name_str, value);
+    gc_free(&gc);
+}
+
+void
+setenv_str_i(struct env_set *es, const char *name, const char *value, const int i)
+{
+    struct gc_arena gc = gc_new();
+    const char *name_str = setenv_format_indexed_name(name, i, &gc);
+    setenv_str(es, name_str, value);
+    gc_free(&gc);
+}
+
+/* return true if filename can be opened for read */
+bool
+test_file(const char *filename)
+{
+    bool ret = false;
+    if (filename)
+    {
+        FILE *fp = platform_fopen(filename, "r");
+        if (fp)
+        {
+            fclose(fp);
+            ret = true;
+        }
+        else
+        {
+            if (openvpn_errno() == EACCES)
+            {
+                msg( M_WARN | M_ERRNO, "Could not access file '%s'", filename);
+            }
+        }
+    }
+
+    dmsg(D_TEST_FILE, "TEST FILE '%s' [%d]",
+         filename ? filename : "UNDEF",
+         ret);
+
+    return ret;
+}
+
+/* create a temporary filename in directory */
+const char *
+create_temp_file(const char *directory, const char *prefix, struct gc_arena *gc)
+{
+    static unsigned int counter;
+    struct buffer fname = alloc_buf_gc(256, gc);
+    int fd;
+    const char *retfname = NULL;
+    unsigned int attempts = 0;
+
+    do
+    {
+        ++attempts;
+        ++counter;
+
+        buf_printf(&fname, PACKAGE "_%s_%08lx%08lx.tmp", prefix,
+                   (unsigned long) get_random(), (unsigned long) get_random());
+
+        retfname = gen_path(directory, BSTR(&fname), gc);
+        if (!retfname)
+        {
+            msg(M_WARN, "Failed to create temporary filename and path");
+            return NULL;
+        }
+
+        /* Atomically create the file.  Errors out if the file already
+         * exists.  */
+        fd = platform_open(retfname, O_CREAT | O_EXCL | O_WRONLY, S_IRUSR | S_IWUSR);
+        if (fd != -1)
+        {
+            close(fd);
+            return retfname;
+        }
+        else if (fd == -1 && errno != EEXIST)
+        {
+            /* Something else went wrong, no need to retry.  */
+            msg(M_WARN | M_ERRNO, "Could not create temporary file '%s'",
+                retfname);
+            return NULL;
+        }
+    }
+    while (attempts < 6);
+
+    msg(M_WARN, "Failed to create temporary file after %i attempts", attempts);
+    return NULL;
+}
+
+#ifdef ENABLE_CRYPTO
+
+/*
+ * Prepend a random string to hostname to prevent DNS caching.
+ * For example, foo.bar.gov would be modified to <random-chars>.foo.bar.gov.
+ * Of course, this requires explicit support in the DNS server (wildcard).
+ */
+const char *
+hostname_randomize(const char *hostname, struct gc_arena *gc)
+{
+#define n_rnd_bytes 6
+
+    uint8_t rnd_bytes[n_rnd_bytes];
+    const char *rnd_str;
+    struct buffer hname = alloc_buf_gc(strlen(hostname)+sizeof(rnd_bytes)*2+4, gc);
+
+    prng_bytes(rnd_bytes, sizeof(rnd_bytes));
+    rnd_str = format_hex_ex(rnd_bytes, sizeof(rnd_bytes), 40, 0, NULL, gc);
+    buf_printf(&hname, "%s.%s", rnd_str, hostname);
+    return BSTR(&hname);
+#undef n_rnd_bytes
+}
+
+#else  /* ifdef ENABLE_CRYPTO */
+
+const char *
+hostname_randomize(const char *hostname, struct gc_arena *gc)
+{
+    msg(M_WARN, "WARNING: hostname randomization disabled when crypto support is not compiled");
+    return hostname;
+}
+
+#endif /* ifdef ENABLE_CRYPTO */
+
+/*
+ * Put a directory and filename together.
+ */
+const char *
+gen_path(const char *directory, const char *filename, struct gc_arena *gc)
+{
+#ifdef _WIN32
+    const int CC_PATH_RESERVED = CC_LESS_THAN|CC_GREATER_THAN|CC_COLON
+                                 |CC_DOUBLE_QUOTE|CC_SLASH|CC_BACKSLASH|CC_PIPE|CC_QUESTION_MARK|CC_ASTERISK;
+#else
+    const int CC_PATH_RESERVED = CC_SLASH;
+#endif
+    const char *safe_filename = string_mod_const(filename, CC_PRINT, CC_PATH_RESERVED, '_', gc);
+
+    if (safe_filename
+        && strcmp(safe_filename, ".")
+        && strcmp(safe_filename, "..")
+#ifdef _WIN32
+        && win_safe_filename(safe_filename)
+#endif
+        )
+    {
+        const size_t outsize = strlen(safe_filename) + (directory ? strlen(directory) : 0) + 16;
+        struct buffer out = alloc_buf_gc(outsize, gc);
+        char dirsep[2];
+
+        dirsep[0] = OS_SPECIFIC_DIRSEP;
+        dirsep[1] = '\0';
+
+        if (directory)
+        {
+            buf_printf(&out, "%s%s", directory, dirsep);
+        }
+        buf_printf(&out, "%s", safe_filename);
+
+        return BSTR(&out);
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+bool
+absolute_pathname(const char *pathname)
+{
+    if (pathname)
+    {
+        const int c = pathname[0];
+#ifdef _WIN32
+        return c == '\\' || (isalpha(c) && pathname[1] == ':' && pathname[2] == '\\');
+#else
+        return c == '/';
+#endif
+    }
+    else
+    {
+        return false;
+    }
+}
+
+#ifdef ENABLE_MANAGEMENT
+
+/* Get username/password from the management interface */
+static bool
+auth_user_pass_mgmt(struct user_pass *up, const char *prefix, const unsigned int flags,
+                    const char *auth_challenge)
+{
+    const char *sc = NULL;
+
+    if (flags & GET_USER_PASS_PREVIOUS_CREDS_FAILED)
+    {
+        management_auth_failure(management, prefix, "previous auth credentials failed");
+    }
+
+#ifdef ENABLE_CLIENT_CR
+    if (auth_challenge && (flags & GET_USER_PASS_STATIC_CHALLENGE))
+    {
+        sc = auth_challenge;
+    }
+#endif
+
+    if (!management_query_user_pass(management, up, prefix, flags, sc))
+    {
+        if ((flags & GET_USER_PASS_NOFATAL) != 0)
+        {
+            return false;
+        }
+        else
+        {
+            msg(M_FATAL, "ERROR: could not read %s username/password/ok/string from management interface", prefix);
+        }
+    }
+    return true;
+}
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+/*
+ * Get and store a username/password
+ */
+
+bool
+get_user_pass_cr(struct user_pass *up,
+                 const char *auth_file,
+                 const char *prefix,
+                 const unsigned int flags,
+                 const char *auth_challenge)
+{
+    struct gc_arena gc = gc_new();
+
+    if (!up->defined)
+    {
+        bool from_authfile = (auth_file && !streq(auth_file, "stdin"));
+        bool username_from_stdin = false;
+        bool password_from_stdin = false;
+        bool response_from_stdin = true;
+
+        if (flags & GET_USER_PASS_PREVIOUS_CREDS_FAILED)
+        {
+            msg(M_WARN, "Note: previous '%s' credentials failed", prefix);
+        }
+
+#ifdef ENABLE_MANAGEMENT
+        /*
+         * Get username/password from management interface?
+         */
+        if (management
+            && (!from_authfile && (flags & GET_USER_PASS_MANAGEMENT))
+            && management_query_user_pass_enabled(management))
+        {
+            response_from_stdin = false;
+            if (!auth_user_pass_mgmt(up, prefix, flags, auth_challenge))
+            {
+                return false;
+            }
+        }
+        else
+#endif /* ifdef ENABLE_MANAGEMENT */
+        /*
+         * Get NEED_OK confirmation from the console
+         */
+        if (flags & GET_USER_PASS_NEED_OK)
+        {
+            struct buffer user_prompt = alloc_buf_gc(128, &gc);
+
+            buf_printf(&user_prompt, "NEED-OK|%s|%s:", prefix, up->username);
+            if (!query_user_SINGLE(BSTR(&user_prompt), BLEN(&user_prompt),
+                                   up->password, USER_PASS_LEN, false))
+            {
+                msg(M_FATAL, "ERROR: could not read %s ok-confirmation from stdin", prefix);
+            }
+
+            if (!strlen(up->password))
+            {
+                strcpy(up->password, "ok");
+            }
+        }
+        else if (flags & GET_USER_PASS_INLINE_CREDS)
+        {
+            struct buffer buf;
+            buf_set_read(&buf, (uint8_t *) auth_file, strlen(auth_file) + 1);
+            if (!(flags & GET_USER_PASS_PASSWORD_ONLY))
+            {
+                buf_parse(&buf, '\n', up->username, USER_PASS_LEN);
+            }
+            buf_parse(&buf, '\n', up->password, USER_PASS_LEN);
+        }
+        /*
+         * Read from auth file unless this is a dynamic challenge request.
+         */
+        else if (from_authfile && !(flags & GET_USER_PASS_DYNAMIC_CHALLENGE))
+        {
+            /*
+             * Try to get username/password from a file.
+             */
+            FILE *fp;
+            char password_buf[USER_PASS_LEN] = { '\0' };
+
+            fp = platform_fopen(auth_file, "r");
+            if (!fp)
+            {
+                msg(M_ERR, "Error opening '%s' auth file: %s", prefix, auth_file);
+            }
+
+            if ((flags & GET_USER_PASS_PASSWORD_ONLY) == 0)
+            {
+                /* Read username first */
+                if (fgets(up->username, USER_PASS_LEN, fp) == NULL)
+                {
+                    msg(M_FATAL, "Error reading username from %s authfile: %s",
+                        prefix,
+                        auth_file);
+                }
+            }
+            chomp(up->username);
+
+            if (fgets(password_buf, USER_PASS_LEN, fp) != NULL)
+            {
+                chomp(password_buf);
+            }
+
+            if (flags & GET_USER_PASS_PASSWORD_ONLY && !password_buf[0])
+            {
+                msg(M_FATAL, "Error reading password from %s authfile: %s", prefix, auth_file);
+            }
+
+            if (password_buf[0])
+            {
+                strncpy(up->password, password_buf, USER_PASS_LEN);
+            }
+            /* The auth-file does not have the password: get both username
+             * and password from the management interface if possible.
+             * Otherwise set to read password from console.
+             */
+#if defined(ENABLE_MANAGEMENT)
+            else if (management
+                     && (flags & GET_USER_PASS_MANAGEMENT)
+                     && management_query_user_pass_enabled(management))
+            {
+                msg(D_LOW, "No password found in %s authfile '%s'. Querying the management interface", prefix, auth_file);
+                if (!auth_user_pass_mgmt(up, prefix, flags, auth_challenge))
+                {
+                    return false;
+                }
+            }
+#endif
+            else
+            {
+                password_from_stdin = 1;
+            }
+
+            fclose(fp);
+
+            if (!(flags & GET_USER_PASS_PASSWORD_ONLY) && strlen(up->username) == 0)
+            {
+                msg(M_FATAL, "ERROR: username from %s authfile '%s' is empty", prefix, auth_file);
+            }
+        }
+        else
+        {
+            username_from_stdin = true;
+            password_from_stdin = true;
+        }
+
+        /*
+         * Get username/password from standard input?
+         */
+        if (username_from_stdin || password_from_stdin || response_from_stdin)
+        {
+#ifdef ENABLE_CLIENT_CR
+            if (auth_challenge && (flags & GET_USER_PASS_DYNAMIC_CHALLENGE) && response_from_stdin)
+            {
+                struct auth_challenge_info *ac = get_auth_challenge(auth_challenge, &gc);
+                if (ac)
+                {
+                    char *response = (char *) gc_malloc(USER_PASS_LEN, false, &gc);
+                    struct buffer packed_resp, challenge;
+
+                    challenge = alloc_buf_gc(14+strlen(ac->challenge_text), &gc);
+                    buf_printf(&challenge, "CHALLENGE: %s", ac->challenge_text);
+                    buf_set_write(&packed_resp, (uint8_t *)up->password, USER_PASS_LEN);
+
+                    if (!query_user_SINGLE(BSTR(&challenge), BLEN(&challenge),
+                                           response, USER_PASS_LEN, BOOL_CAST(ac->flags&CR_ECHO)))
+                    {
+                        msg(M_FATAL, "ERROR: could not read challenge response from stdin");
+                    }
+                    strncpynt(up->username, ac->user, USER_PASS_LEN);
+                    buf_printf(&packed_resp, "CRV1::%s::%s", ac->state_id, response);
+                }
+                else
+                {
+                    msg(M_FATAL, "ERROR: received malformed challenge request from server");
+                }
+            }
+            else
+#endif /* ifdef ENABLE_CLIENT_CR */
+            {
+                struct buffer user_prompt = alloc_buf_gc(128, &gc);
+                struct buffer pass_prompt = alloc_buf_gc(128, &gc);
+
+                query_user_clear();
+                buf_printf(&user_prompt, "Enter %s Username:", prefix);
+                buf_printf(&pass_prompt, "Enter %s Password:", prefix);
+
+                if (username_from_stdin && !(flags & GET_USER_PASS_PASSWORD_ONLY))
+                {
+                    query_user_add(BSTR(&user_prompt), BLEN(&user_prompt),
+                                   up->username, USER_PASS_LEN, true);
+                }
+
+                if (password_from_stdin)
+                {
+                    query_user_add(BSTR(&pass_prompt), BLEN(&pass_prompt),
+                                   up->password, USER_PASS_LEN, false);
+                }
+
+                if (!query_user_exec() )
+                {
+                    msg(M_FATAL, "ERROR: Failed retrieving username or password");
+                }
+
+                if (!(flags & GET_USER_PASS_PASSWORD_ONLY))
+                {
+                    if (strlen(up->username) == 0)
+                    {
+                        msg(M_FATAL, "ERROR: %s username is empty", prefix);
+                    }
+                }
+
+#ifdef ENABLE_CLIENT_CR
+                if (auth_challenge && (flags & GET_USER_PASS_STATIC_CHALLENGE) && response_from_stdin)
+                {
+                    char *response = (char *) gc_malloc(USER_PASS_LEN, false, &gc);
+                    struct buffer packed_resp, challenge;
+                    char *pw64 = NULL, *resp64 = NULL;
+
+                    challenge = alloc_buf_gc(14+strlen(auth_challenge), &gc);
+                    buf_printf(&challenge, "CHALLENGE: %s", auth_challenge);
+
+                    if (!query_user_SINGLE(BSTR(&challenge), BLEN(&challenge),
+                                           response, USER_PASS_LEN,
+                                           BOOL_CAST(flags & GET_USER_PASS_STATIC_CHALLENGE_ECHO)))
+                    {
+                        msg(M_FATAL, "ERROR: could not retrieve static challenge response");
+                    }
+                    if (openvpn_base64_encode(up->password, strlen(up->password), &pw64) == -1
+                        || openvpn_base64_encode(response, strlen(response), &resp64) == -1)
+                    {
+                        msg(M_FATAL, "ERROR: could not base64-encode password/static_response");
+                    }
+                    buf_set_write(&packed_resp, (uint8_t *)up->password, USER_PASS_LEN);
+                    buf_printf(&packed_resp, "SCRV1:%s:%s", pw64, resp64);
+                    string_clear(pw64);
+                    free(pw64);
+                    string_clear(resp64);
+                    free(resp64);
+                }
+#endif /* ifdef ENABLE_CLIENT_CR */
+            }
+        }
+
+        string_mod(up->username, CC_PRINT, CC_CRLF, 0);
+        string_mod(up->password, CC_PRINT, CC_CRLF, 0);
+
+        up->defined = true;
+    }
+
+#if 0
+    msg(M_INFO, "GET_USER_PASS %s u='%s' p='%s'", prefix, up->username, up->password);
+#endif
+
+    gc_free(&gc);
+
+    return true;
+}
+
+#ifdef ENABLE_CLIENT_CR
+
+/*
+ * See management/management-notes.txt for more info on the
+ * the dynamic challenge/response protocol implemented here.
+ */
+struct auth_challenge_info *
+get_auth_challenge(const char *auth_challenge, struct gc_arena *gc)
+{
+    if (auth_challenge)
+    {
+        struct auth_challenge_info *ac;
+        const int len = strlen(auth_challenge);
+        char *work = (char *) gc_malloc(len+1, false, gc);
+        char *cp;
+
+        struct buffer b;
+        buf_set_read(&b, (const uint8_t *)auth_challenge, len);
+
+        ALLOC_OBJ_CLEAR_GC(ac, struct auth_challenge_info, gc);
+
+        /* parse prefix */
+        if (!buf_parse(&b, ':', work, len))
+        {
+            return NULL;
+        }
+        if (strcmp(work, "CRV1"))
+        {
+            return NULL;
+        }
+
+        /* parse flags */
+        if (!buf_parse(&b, ':', work, len))
+        {
+            return NULL;
+        }
+        for (cp = work; *cp != '\0'; ++cp)
+        {
+            const char c = *cp;
+            if (c == 'E')
+            {
+                ac->flags |= CR_ECHO;
+            }
+            else if (c == 'R')
+            {
+                ac->flags |= CR_RESPONSE;
+            }
+        }
+
+        /* parse state ID */
+        if (!buf_parse(&b, ':', work, len))
+        {
+            return NULL;
+        }
+        ac->state_id = string_alloc(work, gc);
+
+        /* parse user name */
+        if (!buf_parse(&b, ':', work, len))
+        {
+            return NULL;
+        }
+        ac->user = (char *) gc_malloc(strlen(work)+1, true, gc);
+        openvpn_base64_decode(work, (void *)ac->user, -1);
+
+        /* parse challenge text */
+        ac->challenge_text = string_alloc(BSTR(&b), gc);
+
+        return ac;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+#endif /* ifdef ENABLE_CLIENT_CR */
+
+#if AUTO_USERID
+
+void
+get_user_pass_auto_userid(struct user_pass *up, const char *tag)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer buf;
+    uint8_t macaddr[6];
+    static uint8_t digest [MD5_DIGEST_LENGTH];
+    static const uint8_t hashprefix[] = "AUTO_USERID_DIGEST";
+
+    const md_kt_t *md5_kt = md_kt_get("MD5");
+    md_ctx_t *ctx;
+
+    CLEAR(*up);
+    buf_set_write(&buf, (uint8_t *)up->username, USER_PASS_LEN);
+    buf_printf(&buf, "%s", TARGET_PREFIX);
+    if (get_default_gateway_mac_addr(macaddr))
+    {
+        dmsg(D_AUTO_USERID, "GUPAU: macaddr=%s", format_hex_ex(macaddr, sizeof(macaddr), 0, 1, ":", &gc));
+        ctx = md_ctx_new();
+        md_ctx_init(ctx, md5_kt);
+        md_ctx_update(ctx, hashprefix, sizeof(hashprefix) - 1);
+        md_ctx_update(ctx, macaddr, sizeof(macaddr));
+        md_ctx_final(ctx, digest);
+        md_ctx_cleanup(ctx);
+        md_ctx_free(ctx);
+        buf_printf(&buf, "%s", format_hex_ex(digest, sizeof(digest), 0, 256, " ", &gc));
+    }
+    else
+    {
+        buf_printf(&buf, "UNKNOWN");
+    }
+    if (tag && strcmp(tag, "stdin"))
+    {
+        buf_printf(&buf, "-%s", tag);
+    }
+    up->defined = true;
+    gc_free(&gc);
+
+    dmsg(D_AUTO_USERID, "GUPAU: AUTO_USERID: '%s'", up->username);
+}
+
+#endif /* if AUTO_USERID */
+
+void
+purge_user_pass(struct user_pass *up, const bool force)
+{
+    const bool nocache = up->nocache;
+    static bool warn_shown = false;
+    if (nocache || force)
+    {
+        secure_memzero(up, sizeof(*up));
+        up->nocache = nocache;
+    }
+    /*
+     * don't show warning if the pass has been replaced by a token: this is an
+     * artificial "auth-nocache"
+     */
+    else if (!warn_shown)
+    {
+        msg(M_WARN, "WARNING: this configuration may cache passwords in memory -- use the auth-nocache option to prevent this");
+        warn_shown = true;
+    }
+}
+
+void
+set_auth_token(struct user_pass *up, struct user_pass *tk, const char *token)
+{
+
+    if (token && strlen(token) && up && up->defined)
+    {
+        strncpynt(tk->password, token, USER_PASS_LEN);
+        strncpynt(tk->username, up->username, USER_PASS_LEN);
+        tk->defined = true;
+    }
+
+    /* Cleans user/pass for nocache */
+    purge_user_pass(up, false);
+}
+
+/*
+ * Process string received by untrusted peer before
+ * printing to console or log file.
+ *
+ * Assumes that string has been null terminated.
+ */
+const char *
+safe_print(const char *str, struct gc_arena *gc)
+{
+    return string_mod_const(str, CC_PRINT, CC_CRLF, '.', gc);
+}
+
+static bool
+is_password_env_var(const char *str)
+{
+    return (strncmp(str, "password", 8) == 0);
+}
+
+bool
+env_allowed(const char *str)
+{
+    return (script_security >= SSEC_PW_ENV || !is_password_env_var(str));
+}
+
+bool
+env_safe_to_print(const char *str)
+{
+#ifndef UNSAFE_DEBUG
+    if (is_password_env_var(str))
+    {
+        return false;
+    }
+#endif
+    return true;
+}
+
+/* Make arrays of strings */
+
+const char **
+make_env_array(const struct env_set *es,
+               const bool check_allowed,
+               struct gc_arena *gc)
+{
+    char **ret = NULL;
+    struct env_item *e = NULL;
+    int i = 0, n = 0;
+
+    /* figure length of es */
+    if (es)
+    {
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            ++n;
+        }
+    }
+
+    /* alloc return array */
+    ALLOC_ARRAY_CLEAR_GC(ret, char *, n+1, gc);
+
+    /* fill return array */
+    if (es)
+    {
+        i = 0;
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            if (!check_allowed || env_allowed(e->string))
+            {
+                ASSERT(i < n);
+                ret[i++] = e->string;
+            }
+        }
+    }
+
+    ret[i] = NULL;
+    return (const char **)ret;
+}
+
+const char **
+make_arg_array(const char *first, const char *parms, struct gc_arena *gc)
+{
+    char **ret = NULL;
+    int base = 0;
+    const int max_parms = MAX_PARMS + 2;
+    int n = 0;
+
+    /* alloc return array */
+    ALLOC_ARRAY_CLEAR_GC(ret, char *, max_parms, gc);
+
+    /* process first parameter, if provided */
+    if (first)
+    {
+        ret[base++] = string_alloc(first, gc);
+    }
+
+    if (parms)
+    {
+        n = parse_line(parms, &ret[base], max_parms - base - 1, "make_arg_array", 0, M_WARN, gc);
+        ASSERT(n >= 0 && n + base + 1 <= max_parms);
+    }
+    ret[base + n] = NULL;
+
+    return (const char **)ret;
+}
+
+static const char **
+make_inline_array(const char *str, struct gc_arena *gc)
+{
+    char line[OPTION_LINE_SIZE];
+    struct buffer buf;
+    int len = 0;
+    char **ret = NULL;
+    int i = 0;
+
+    buf_set_read(&buf, (const uint8_t *) str, strlen(str));
+    while (buf_parse(&buf, '\n', line, sizeof(line)))
+    {
+        ++len;
+    }
+
+    /* alloc return array */
+    ALLOC_ARRAY_CLEAR_GC(ret, char *, len + 1, gc);
+
+    buf_set_read(&buf, (const uint8_t *) str, strlen(str));
+    while (buf_parse(&buf, '\n', line, sizeof(line)))
+    {
+        chomp(line);
+        ASSERT(i < len);
+        ret[i] = string_alloc(skip_leading_whitespace(line), gc);
+        ++i;
+    }
+    ASSERT(i <= len);
+    ret[i] = NULL;
+    return (const char **)ret;
+}
+
+static const char **
+make_arg_copy(char **p, struct gc_arena *gc)
+{
+    char **ret = NULL;
+    const int len = string_array_len((const char **)p);
+    const int max_parms = len + 1;
+    int i;
+
+    /* alloc return array */
+    ALLOC_ARRAY_CLEAR_GC(ret, char *, max_parms, gc);
+
+    for (i = 0; i < len; ++i)
+    {
+        ret[i] = p[i];
+    }
+
+    return (const char **)ret;
+}
+
+const char **
+make_extended_arg_array(char **p, struct gc_arena *gc)
+{
+    const int argc = string_array_len((const char **)p);
+    if (!strcmp(p[0], INLINE_FILE_TAG) && argc == 2)
+    {
+        return make_inline_array(p[1], gc);
+    }
+    else if (argc == 0)
+    {
+        return make_arg_array(NULL, NULL, gc);
+    }
+    else if (argc == 1)
+    {
+        return make_arg_array(p[0], NULL, gc);
+    }
+    else if (argc == 2)
+    {
+        return make_arg_array(p[0], p[1], gc);
+    }
+    else
+    {
+        return make_arg_copy(p, gc);
+    }
+}
+
+/*
+ * Remove security-sensitive strings from control message
+ * so that they will not be output to log file.
+ */
+const char *
+sanitize_control_message(const char *src, struct gc_arena *gc)
+{
+    char *ret = gc_malloc(strlen(src)+1, false, gc);
+    char *dest = ret;
+    bool redact = false;
+    int skip = 0;
+
+    for (;; )
+    {
+        const char c = *src;
+        if (c == '\0')
+        {
+            break;
+        }
+        if (c == 'S' && !strncmp(src, "SESS_ID_", 8))
+        {
+            skip = 7;
+            redact = true;
+        }
+        else if (c == 'e' && !strncmp(src, "echo ", 5))
+        {
+            skip = 4;
+            redact = true;
+        }
+        else if (!check_debug_level(D_SHOW_KEYS)
+                 && (c == 'a' && !strncmp(src, "auth-token ", 11)))
+        {
+            /* Unless --verb is 7 or higher (D_SHOW_KEYS), hide
+             * the auth-token value coming in the src string
+             */
+            skip = 10;
+            redact = true;
+        }
+
+        if (c == ',') /* end of redacted item? */
+        {
+            skip = 0;
+            redact = false;
+        }
+
+        if (redact)
+        {
+            if (skip > 0)
+            {
+                --skip;
+                *dest++ = c;
+            }
+        }
+        else
+        {
+            *dest++ = c;
+        }
+
+        ++src;
+    }
+    *dest = '\0';
+    return ret;
+}
+
+/**
+ * Will set or query for a global compat flag.  To modify the compat flags
+ * the COMPAT_FLAG_SET must be bitwise ORed together with the flag to set.
+ * If no "operator" flag is given it defaults to COMPAT_FLAG_QUERY,
+ * which returns the flag state.
+ *
+ * @param  flag  Flag to be set/queried for bitwise ORed with the operator flag
+ * @return Returns 0 if the flag is not set, otherwise the 'flag' value is returned
+ */
+bool
+compat_flag(unsigned int flag)
+{
+    static unsigned int compat_flags = 0;
+
+    if (flag & COMPAT_FLAG_SET)
+    {
+        compat_flags |= (flag >> 1);
+    }
+
+    return (compat_flags & (flag >> 1));
+
+}
+
+#if P2MP_SERVER
+
+/* helper to parse peer_info received from multi client, validate
+ * (this is untrusted data) and put into environment
+ */
+bool
+validate_peer_info_line(char *line)
+{
+    uint8_t c;
+    int state = 0;
+    while (*line)
+    {
+        c = *line;
+        switch (state)
+        {
+            case 0:
+            case 1:
+                if (c == '=' && state == 1)
+                {
+                    state = 2;
+                }
+                else if (isalnum(c) || c == '_')
+                {
+                    state = 1;
+                }
+                else
+                {
+                    return false;
+                }
+
+            case 2:
+                /* after the '=', replace non-printable or shell meta with '_' */
+                if (!isprint(c) || isspace(c)
+                    || c == '$' || c == '(' || c == '`')
+                {
+                    *line = '_';
+                }
+        }
+        line++;
+    }
+    return (state == 2);
+}
+
+void
+output_peer_info_env(struct env_set *es, const char *peer_info)
+{
+    char line[256];
+    struct buffer buf;
+    buf_set_read(&buf, (const uint8_t *) peer_info, strlen(peer_info));
+    while (buf_parse(&buf, '\n', line, sizeof(line)))
+    {
+        chomp(line);
+        if (validate_peer_info_line(line)
+            && (strncmp(line, "IV_", 3) == 0 || strncmp(line, "UV_", 3) == 0) )
+        {
+            msg(M_INFO, "peer info: %s", line);
+            env_set_add(es, line);
+        }
+        else
+        {
+            msg(M_WARN, "validation failed on peer_info line received from client");
+        }
+    }
+}
+
+#endif /* P2MP_SERVER */
diff --git a/src/openvpn/misc.h b/src/openvpn/misc.h
new file mode 100644
index 0000000..8a34f43
--- /dev/null
+++ b/src/openvpn/misc.h
@@ -0,0 +1,317 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MISC_H
+#define MISC_H
+
+#include "argv.h"
+#include "basic.h"
+#include "common.h"
+#include "integer.h"
+#include "buffer.h"
+#include "platform.h"
+
+/* socket descriptor passed by inetd/xinetd server to us */
+#define INETD_SOCKET_DESCRIPTOR 0
+
+/* forward declarations */
+struct plugin_list;
+
+/*
+ * Handle environmental variable lists
+ */
+
+struct env_item {
+    char *string;
+    struct env_item *next;
+};
+
+struct env_set {
+    struct gc_arena *gc;
+    struct env_item *list;
+};
+
+/* system flags */
+#define S_SCRIPT (1<<0)
+#define S_FATAL  (1<<1)
+
+const char *system_error_message(int, struct gc_arena *gc);
+
+/* openvpn_execve return codes */
+#define OPENVPN_EXECVE_ERROR       -1 /* generic error while forking to run an external program */
+#define OPENVPN_EXECVE_NOT_ALLOWED -2 /* external program not run due to script security */
+#define OPENVPN_EXECVE_FAILURE    127 /* exit code passed back from child when execve fails */
+
+/* wrapper around the execve() call */
+int openvpn_popen(const struct argv *a,  const struct env_set *es);
+
+int openvpn_execve(const struct argv *a, const struct env_set *es, const unsigned int flags);
+
+bool openvpn_execve_check(const struct argv *a, const struct env_set *es, const unsigned int flags, const char *error_message);
+
+bool openvpn_execve_allowed(const unsigned int flags);
+
+static inline bool
+openvpn_run_script(const struct argv *a, const struct env_set *es, const unsigned int flags, const char *hook)
+{
+    char msg[256];
+
+    openvpn_snprintf(msg, sizeof(msg), "WARNING: Failed running command (%s)", hook);
+    return openvpn_execve_check(a, es, flags | S_SCRIPT, msg);
+}
+
+
+/* Set standard file descriptors to /dev/null */
+void set_std_files_to_null(bool stdin_only);
+
+/* dup inetd/xinetd socket descriptor and save */
+extern int inetd_socket_descriptor;
+void save_inetd_socket_descriptor(void);
+
+/* set/delete environmental variable */
+void setenv_str_ex(struct env_set *es,
+                   const char *name,
+                   const char *value,
+                   const unsigned int name_include,
+                   const unsigned int name_exclude,
+                   const char name_replace,
+                   const unsigned int value_include,
+                   const unsigned int value_exclude,
+                   const char value_replace);
+
+void setenv_counter(struct env_set *es, const char *name, counter_type value);
+
+void setenv_int(struct env_set *es, const char *name, int value);
+
+void setenv_unsigned(struct env_set *es, const char *name, unsigned int value);
+
+void setenv_str(struct env_set *es, const char *name, const char *value);
+
+void setenv_str_safe(struct env_set *es, const char *name, const char *value);
+
+void setenv_del(struct env_set *es, const char *name);
+
+/**
+ * Store the supplied name value pair in the env_set.  If the variable with the
+ * supplied name  already exists, append _N to the name, starting at N=1.
+ */
+void setenv_str_incr(struct env_set *es, const char *name, const char *value);
+
+void setenv_int_i(struct env_set *es, const char *name, const int value, const int i);
+
+void setenv_str_i(struct env_set *es, const char *name, const char *value, const int i);
+
+/* struct env_set functions */
+
+struct env_set *env_set_create(struct gc_arena *gc);
+
+void env_set_destroy(struct env_set *es);
+
+bool env_set_del(struct env_set *es, const char *str);
+
+void env_set_add(struct env_set *es, const char *str);
+
+const char *env_set_get(const struct env_set *es, const char *name);
+
+void env_set_print(int msglevel, const struct env_set *es);
+
+void env_set_inherit(struct env_set *es, const struct env_set *src);
+
+/* Make arrays of strings */
+
+const char **make_env_array(const struct env_set *es,
+                            const bool check_allowed,
+                            struct gc_arena *gc);
+
+const char **make_arg_array(const char *first, const char *parms, struct gc_arena *gc);
+
+const char **make_extended_arg_array(char **p, struct gc_arena *gc);
+
+/* an analogue to the random() function, but use OpenSSL functions if available */
+#ifdef ENABLE_CRYPTO
+long int get_random(void);
+
+#else
+#define get_random random
+#endif
+
+/* return true if filename can be opened for read */
+bool test_file(const char *filename);
+
+/* create a temporary file in directory, returns the filename of the created file */
+const char *create_temp_file(const char *directory, const char *prefix, struct gc_arena *gc);
+
+/* put a directory and filename together */
+const char *gen_path(const char *directory, const char *filename, struct gc_arena *gc);
+
+/* return true if pathname is absolute */
+bool absolute_pathname(const char *pathname);
+
+/* prepend a random prefix to hostname (need ENABLE_CRYPTO) */
+const char *hostname_randomize(const char *hostname, struct gc_arena *gc);
+
+/*
+ * Get and store a username/password
+ */
+
+struct user_pass
+{
+    bool defined;
+    bool nocache;
+    bool wait_for_push; /* true if this object is waiting for a push-reply */
+
+/* max length of username/password */
+#ifdef ENABLE_PKCS11
+#define USER_PASS_LEN 4096
+#else
+#define USER_PASS_LEN 128
+#endif
+    char username[USER_PASS_LEN];
+    char password[USER_PASS_LEN];
+};
+
+#ifdef ENABLE_CLIENT_CR
+/*
+ * Challenge response info on client as pushed by server.
+ */
+struct auth_challenge_info {
+#define CR_ECHO     (1<<0)  /* echo response when typed by user */
+#define CR_RESPONSE (1<<1)  /* response needed */
+    unsigned int flags;
+
+    const char *user;
+    const char *state_id;
+    const char *challenge_text;
+};
+
+struct auth_challenge_info *get_auth_challenge(const char *auth_challenge, struct gc_arena *gc);
+
+/*
+ * Challenge response info on client as pushed by server.
+ */
+struct static_challenge_info {
+#define SC_ECHO     (1<<0)  /* echo response when typed by user */
+    unsigned int flags;
+
+    const char *challenge_text;
+};
+
+#else  /* ifdef ENABLE_CLIENT_CR */
+struct auth_challenge_info {};
+struct static_challenge_info {};
+#endif /* ifdef ENABLE_CLIENT_CR */
+
+/*
+ * Flags for get_user_pass and management_query_user_pass
+ */
+#define GET_USER_PASS_MANAGEMENT    (1<<0)
+/* GET_USER_PASS_SENSITIVE     (1<<1)  not used anymore */
+#define GET_USER_PASS_PASSWORD_ONLY (1<<2)
+#define GET_USER_PASS_NEED_OK       (1<<3)
+#define GET_USER_PASS_NOFATAL       (1<<4)
+#define GET_USER_PASS_NEED_STR      (1<<5)
+#define GET_USER_PASS_PREVIOUS_CREDS_FAILED (1<<6)
+
+#define GET_USER_PASS_DYNAMIC_CHALLENGE      (1<<7) /* CRV1 protocol  -- dynamic challenge */
+#define GET_USER_PASS_STATIC_CHALLENGE       (1<<8) /* SCRV1 protocol -- static challenge */
+#define GET_USER_PASS_STATIC_CHALLENGE_ECHO  (1<<9) /* SCRV1 protocol -- echo response */
+
+#define GET_USER_PASS_INLINE_CREDS (1<<10)  /* indicates that auth_file is actually inline creds */
+
+bool get_user_pass_cr(struct user_pass *up,
+                      const char *auth_file,
+                      const char *prefix,
+                      const unsigned int flags,
+                      const char *auth_challenge);
+
+static inline bool
+get_user_pass(struct user_pass *up,
+              const char *auth_file,
+              const char *prefix,
+              const unsigned int flags)
+{
+    return get_user_pass_cr(up, auth_file, prefix, flags, NULL);
+}
+
+void fail_user_pass(const char *prefix,
+                    const unsigned int flags,
+                    const char *reason);
+
+void purge_user_pass(struct user_pass *up, const bool force);
+
+void set_auth_token(struct user_pass *up, struct user_pass *tk,
+                    const char *token);
+
+/*
+ * Process string received by untrusted peer before
+ * printing to console or log file.
+ * Assumes that string has been null terminated.
+ */
+const char *safe_print(const char *str, struct gc_arena *gc);
+
+/* returns true if environmental variable safe to print to log */
+bool env_safe_to_print(const char *str);
+
+/* returns true if environmental variable may be passed to an external program */
+bool env_allowed(const char *str);
+
+void configure_path(void);
+
+const char *sanitize_control_message(const char *str, struct gc_arena *gc);
+
+#if AUTO_USERID
+void get_user_pass_auto_userid(struct user_pass *up, const char *tag);
+
+#endif
+
+/*
+ * /sbin/ip path, may be overridden
+ */
+#ifdef ENABLE_IPROUTE
+extern const char *iproute_path;
+#endif
+
+/* Script security */
+#define SSEC_NONE      0 /* strictly no calling of external programs */
+#define SSEC_BUILT_IN  1 /* only call built-in programs such as ifconfig, route, netsh, etc.*/
+#define SSEC_SCRIPTS   2 /* allow calling of built-in programs and user-defined scripts */
+#define SSEC_PW_ENV    3 /* allow calling of built-in programs and user-defined scripts that may receive a password as an environmental variable */
+extern int script_security; /* GLOBAL */
+
+
+#define COMPAT_FLAG_QUERY         0       /** compat_flags operator: Query for a flag */
+#define COMPAT_FLAG_SET           (1<<0)  /** compat_flags operator: Set a compat flag */
+#define COMPAT_NAMES              (1<<1)  /** compat flag: --compat-names set */
+#define COMPAT_NO_NAME_REMAPPING  (1<<2)  /** compat flag: --compat-names without char remapping */
+bool compat_flag(unsigned int flag);
+
+#if P2MP_SERVER
+/* helper to parse peer_info received from multi client, validate
+ * (this is untrusted data) and put into environment */
+bool validate_peer_info_line(char *line);
+
+void output_peer_info_env(struct env_set *es, const char *peer_info);
+
+#endif /* P2MP_SERVER */
+
+#endif /* ifndef MISC_H */
diff --git a/src/openvpn/mroute.c b/src/openvpn/mroute.c
new file mode 100644
index 0000000..db8c987
--- /dev/null
+++ b/src/openvpn/mroute.c
@@ -0,0 +1,597 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "mroute.h"
+#include "proto.h"
+#include "error.h"
+#include "socket.h"
+
+#include "memdbg.h"
+
+void
+mroute_addr_init(struct mroute_addr *addr)
+{
+    CLEAR(*addr);
+}
+
+/*
+ * Ethernet multicast addresses.
+ */
+
+static inline bool
+is_mac_mcast_addr(const uint8_t *mac)
+{
+    return (bool) (mac[0] & 1);
+}
+
+static inline bool
+is_mac_mcast_maddr(const struct mroute_addr *addr)
+{
+    return (addr->type & MR_ADDR_MASK) == MR_ADDR_ETHER
+           && is_mac_mcast_addr(addr->eth_addr);
+}
+
+/*
+ * Don't learn certain addresses.
+ */
+bool
+mroute_learnable_address(const struct mroute_addr *addr, struct gc_arena *gc)
+{
+    int i;
+    bool all_zeros = true;
+    bool all_ones = true;
+
+    for (i = 0; i < addr->len; ++i)
+    {
+        int b = addr->raw_addr[i];
+        if (b != 0x00)
+        {
+            all_zeros = false;
+        }
+        if (b != 0xFF)
+        {
+            all_ones = false;
+        }
+    }
+
+    /* only networkss shorter than 8 bits are allowed to be all 0s. */
+    if (all_zeros
+        && !((addr->type & MR_WITH_NETBITS) && (addr->netbits < 8)))
+    {
+        msg(D_MULTI_LOW, "Can't learn %s: network is all 0s, but netbits >= 8",
+            mroute_addr_print(addr, gc));
+        return false;
+    }
+
+    if (all_ones)
+    {
+        msg(D_MULTI_LOW, "Can't learn %s: network is all 1s",
+            mroute_addr_print(addr, gc));
+        return false;
+    }
+
+    if (is_mac_mcast_maddr(addr))
+    {
+        msg(D_MULTI_LOW, "Can't learn %s: network is a multicast address",
+            mroute_addr_print(addr, gc));
+        return false;
+    }
+
+    return true;
+}
+
+static inline void
+mroute_get_in_addr_t(struct mroute_addr *ma, const in_addr_t src, unsigned int mask)
+{
+    if (ma)
+    {
+        ma->type = MR_ADDR_IPV4 | mask;
+        ma->netbits = 0;
+        ma->len = 4;
+        ma->v4.addr = src;
+    }
+}
+
+static inline void
+mroute_get_in6_addr(struct mroute_addr *ma, const struct in6_addr src, unsigned int mask)
+{
+    if (ma)
+    {
+        ma->type = MR_ADDR_IPV6 | mask;
+        ma->netbits = 0;
+        ma->len = 16;
+        ma->v6.addr = src;
+    }
+}
+
+static inline bool
+mroute_is_mcast(const in_addr_t addr)
+{
+    return ((addr & htonl(IP_MCAST_SUBNET_MASK)) == htonl(IP_MCAST_NETWORK));
+}
+
+/* RFC 4291, 2.7, "binary 11111111 at the start of an address identifies
+ *                 the address as being a multicast address"
+ */
+static inline bool
+mroute_is_mcast_ipv6(const struct in6_addr addr)
+{
+    return (addr.s6_addr[0] == 0xff);
+}
+
+#ifdef ENABLE_PF
+
+static unsigned int
+mroute_extract_addr_arp(struct mroute_addr *src,
+                        struct mroute_addr *dest,
+                        const struct buffer *buf)
+{
+    unsigned int ret = 0;
+    if (BLEN(buf) >= (int) sizeof(struct openvpn_arp))
+    {
+        const struct openvpn_arp *arp = (const struct openvpn_arp *) BPTR(buf);
+        if (arp->mac_addr_type == htons(0x0001)
+            && arp->proto_addr_type == htons(0x0800)
+            && arp->mac_addr_size == 0x06
+            && arp->proto_addr_size == 0x04)
+        {
+            mroute_get_in_addr_t(src, arp->ip_src, MR_ARP);
+            mroute_get_in_addr_t(dest, arp->ip_dest, MR_ARP);
+
+            /* multicast packet? */
+            if (mroute_is_mcast(arp->ip_dest))
+            {
+                ret |= MROUTE_EXTRACT_MCAST;
+            }
+
+            ret |= MROUTE_EXTRACT_SUCCEEDED;
+        }
+    }
+    return ret;
+}
+
+#endif /* ifdef ENABLE_PF */
+
+unsigned int
+mroute_extract_addr_ip(struct mroute_addr *src, struct mroute_addr *dest,
+                       const struct buffer *buf)
+{
+    unsigned int ret = 0;
+    if (BLEN(buf) >= 1)
+    {
+        switch (OPENVPN_IPH_GET_VER(*BPTR(buf)))
+        {
+            case 4:
+                if (BLEN(buf) >= (int) sizeof(struct openvpn_iphdr))
+                {
+                    const struct openvpn_iphdr *ip = (const struct openvpn_iphdr *) BPTR(buf);
+
+                    mroute_get_in_addr_t(src, ip->saddr, 0);
+                    mroute_get_in_addr_t(dest, ip->daddr, 0);
+
+                    /* multicast packet? */
+                    if (mroute_is_mcast(ip->daddr))
+                    {
+                        ret |= MROUTE_EXTRACT_MCAST;
+                    }
+
+                    /* IGMP message? */
+                    if (ip->protocol == OPENVPN_IPPROTO_IGMP)
+                    {
+                        ret |= MROUTE_EXTRACT_IGMP;
+                    }
+
+                    ret |= MROUTE_EXTRACT_SUCCEEDED;
+                }
+                break;
+
+            case 6:
+                if (BLEN(buf) >= (int) sizeof(struct openvpn_ipv6hdr))
+                {
+                    const struct openvpn_ipv6hdr *ipv6 = (const struct openvpn_ipv6hdr *) BPTR(buf);
+#if 0                           /* very basic debug */
+                    struct gc_arena gc = gc_new();
+                    msg( M_INFO, "IPv6 packet! src=%s, dst=%s",
+                         print_in6_addr( ipv6->saddr, 0, &gc ),
+                         print_in6_addr( ipv6->daddr, 0, &gc ));
+                    gc_free(&gc);
+#endif
+
+                    mroute_get_in6_addr(src, ipv6->saddr, 0);
+                    mroute_get_in6_addr(dest, ipv6->daddr, 0);
+
+                    if (mroute_is_mcast_ipv6(ipv6->daddr))
+                    {
+                        ret |= MROUTE_EXTRACT_MCAST;
+                    }
+
+                    ret |= MROUTE_EXTRACT_SUCCEEDED;
+                }
+                break;
+
+            default:
+                msg(M_WARN, "IP packet with unknown IP version=%d seen",
+                    OPENVPN_IPH_GET_VER(*BPTR(buf)));
+        }
+    }
+    return ret;
+}
+
+unsigned int
+mroute_extract_addr_ether(struct mroute_addr *src,
+                          struct mroute_addr *dest,
+                          struct mroute_addr *esrc,
+                          struct mroute_addr *edest,
+                          const struct buffer *buf)
+{
+    unsigned int ret = 0;
+    if (BLEN(buf) >= (int) sizeof(struct openvpn_ethhdr))
+    {
+        const struct openvpn_ethhdr *eth = (const struct openvpn_ethhdr *) BPTR(buf);
+        if (src)
+        {
+            src->type = MR_ADDR_ETHER;
+            src->netbits = 0;
+            src->len = 6;
+            memcpy(src->eth_addr, eth->source, sizeof(dest->eth_addr));
+        }
+        if (dest)
+        {
+            dest->type = MR_ADDR_ETHER;
+            dest->netbits = 0;
+            dest->len = 6;
+            memcpy(dest->eth_addr, eth->dest, sizeof(dest->eth_addr));
+
+            /* ethernet broadcast/multicast packet? */
+            if (is_mac_mcast_addr(eth->dest))
+            {
+                ret |= MROUTE_EXTRACT_BCAST;
+            }
+        }
+
+        ret |= MROUTE_EXTRACT_SUCCEEDED;
+
+#ifdef ENABLE_PF
+        if (esrc || edest)
+        {
+            struct buffer b = *buf;
+            if (buf_advance(&b, sizeof(struct openvpn_ethhdr)))
+            {
+                switch (ntohs(eth->proto))
+                {
+                    case OPENVPN_ETH_P_IPV4:
+                        ret |= (mroute_extract_addr_ip(esrc, edest, &b) << MROUTE_SEC_SHIFT);
+                        break;
+
+                    case OPENVPN_ETH_P_ARP:
+                        ret |= (mroute_extract_addr_arp(esrc, edest, &b) << MROUTE_SEC_SHIFT);
+                        break;
+                }
+            }
+        }
+#endif
+    }
+    return ret;
+}
+
+/*
+ * Translate a struct openvpn_sockaddr (osaddr)
+ * to a struct mroute_addr (addr).
+ */
+bool
+mroute_extract_openvpn_sockaddr(struct mroute_addr *addr,
+                                const struct openvpn_sockaddr *osaddr,
+                                bool use_port)
+{
+    switch (osaddr->addr.sa.sa_family)
+    {
+        case AF_INET:
+        {
+            if (use_port)
+            {
+                addr->type = MR_ADDR_IPV4 | MR_WITH_PORT;
+                addr->netbits = 0;
+                addr->len = 6;
+                addr->v4.addr = osaddr->addr.in4.sin_addr.s_addr;
+                addr->v4.port = osaddr->addr.in4.sin_port;
+            }
+            else
+            {
+                addr->type = MR_ADDR_IPV4;
+                addr->netbits = 0;
+                addr->len = 4;
+                addr->v4.addr = osaddr->addr.in4.sin_addr.s_addr;
+            }
+            return true;
+        }
+
+        case AF_INET6:
+            if (use_port)
+            {
+                addr->type = MR_ADDR_IPV6 | MR_WITH_PORT;
+                addr->netbits = 0;
+                addr->len = 18;
+                addr->v6.addr = osaddr->addr.in6.sin6_addr;
+                addr->v6.port = osaddr->addr.in6.sin6_port;
+            }
+            else
+            {
+                addr->type = MR_ADDR_IPV6;
+                addr->netbits = 0;
+                addr->len = 16;
+                addr->v6.addr = osaddr->addr.in6.sin6_addr;
+            }
+            return true;
+    }
+    return false;
+}
+
+/*
+ * Zero off the host bits in an address, leaving
+ * only the network bits, using the netbits member of
+ * struct mroute_addr as the controlling parameter.
+ *
+ * TODO: this is called for route-lookup for every yet-unhashed
+ * destination address, so for lots of active net-iroutes, this
+ * might benefit from some "zeroize 32 bit at a time" improvements
+ */
+void
+mroute_addr_mask_host_bits(struct mroute_addr *ma)
+{
+    if ((ma->type & MR_ADDR_MASK) == MR_ADDR_IPV4)
+    {
+        in_addr_t addr = ntohl(ma->v4.addr);
+        addr &= netbits_to_netmask(ma->netbits);
+        ma->v4.addr = htonl(addr);
+    }
+    else if ((ma->type & MR_ADDR_MASK) == MR_ADDR_IPV6)
+    {
+        int byte = sizeof(ma->v6.addr) - 1;     /* rightmost byte in address */
+        int bits_to_clear = 128 - ma->netbits;
+
+        while (byte >= 0 && bits_to_clear > 0)
+        {
+            if (bits_to_clear >= 8)
+            {
+                ma->v6.addr.s6_addr[byte--] = 0;
+                bits_to_clear -= 8;
+            }
+            else
+            {
+                ma->v6.addr.s6_addr[byte--] &= (IPV4_NETMASK_HOST << bits_to_clear);
+                bits_to_clear = 0;
+            }
+        }
+        ASSERT( bits_to_clear == 0 );
+    }
+    else
+    {
+        ASSERT(0);
+    }
+}
+
+/*
+ * The mroute_addr hash function takes into account the
+ * address type, number of bits in the network address,
+ * and the actual address.
+ */
+uint32_t
+mroute_addr_hash_function(const void *key, uint32_t iv)
+{
+    return hash_func(mroute_addr_hash_ptr((const struct mroute_addr *) key),
+                     mroute_addr_hash_len((const struct mroute_addr *) key),
+                     iv);
+}
+
+bool
+mroute_addr_compare_function(const void *key1, const void *key2)
+{
+    return mroute_addr_equal((const struct mroute_addr *) key1,
+                             (const struct mroute_addr *) key2);
+}
+
+const char *
+mroute_addr_print(const struct mroute_addr *ma,
+                  struct gc_arena *gc)
+{
+    return mroute_addr_print_ex(ma, MAPF_IA_EMPTY_IF_UNDEF, gc);
+}
+
+const char *
+mroute_addr_print_ex(const struct mroute_addr *ma,
+                     const unsigned int flags,
+                     struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    if (ma)
+    {
+        struct mroute_addr maddr = *ma;
+
+        switch (maddr.type & MR_ADDR_MASK)
+        {
+            case MR_ADDR_ETHER:
+                buf_printf(&out, "%s", format_hex_ex(ma->eth_addr,
+                                                     sizeof(ma->eth_addr), 0, 1, ":", gc));
+                break;
+
+            case MR_ADDR_IPV4:
+            {
+                if ((flags & MAPF_SHOW_ARP) && (maddr.type & MR_ARP))
+                {
+                    buf_printf(&out, "ARP/");
+                }
+                buf_printf(&out, "%s", print_in_addr_t(ntohl(maddr.v4.addr),
+                                                       (flags & MAPF_IA_EMPTY_IF_UNDEF) ? IA_EMPTY_IF_UNDEF : 0, gc));
+                if (maddr.type & MR_WITH_NETBITS)
+                {
+                    if (flags & MAPF_SUBNET)
+                    {
+                        const in_addr_t netmask = netbits_to_netmask(maddr.netbits);
+                        buf_printf(&out, "/%s", print_in_addr_t(netmask, 0, gc));
+                    }
+                    else
+                    {
+                        buf_printf(&out, "/%d", maddr.netbits);
+                    }
+                }
+                if (maddr.type & MR_WITH_PORT)
+                {
+                    buf_printf(&out, ":%d", ntohs(maddr.v4.port));
+                }
+            }
+            break;
+
+            case MR_ADDR_IPV6:
+            {
+                if (IN6_IS_ADDR_V4MAPPED( &maddr.v6.addr ) )
+                {
+                    buf_printf(&out, "%s", print_in_addr_t(maddr.v4mappedv6.addr,
+                                                           IA_NET_ORDER, gc));
+                    /* we only print port numbers for v4mapped v6 as of
+                     * today, because "v6addr:port" is too ambiguous
+                     */
+                    if (maddr.type & MR_WITH_PORT)
+                    {
+                        buf_printf(&out, ":%d", ntohs(maddr.v6.port));
+                    }
+                }
+                else
+                {
+                    buf_printf(&out, "%s", print_in6_addr(maddr.v6.addr, 0, gc));
+                }
+                if (maddr.type & MR_WITH_NETBITS)
+                {
+                    buf_printf(&out, "/%d", maddr.netbits);
+                }
+            }
+            break;
+
+            default:
+                buf_printf(&out, "UNKNOWN");
+                break;
+        }
+        return BSTR(&out);
+    }
+    else
+    {
+        return "[NULL]";
+    }
+}
+
+/*
+ * mroute_helper's main job is keeping track of
+ * currently used CIDR netlengths, so we don't
+ * have to cycle through all 33.
+ */
+
+struct mroute_helper *
+mroute_helper_init(int ageable_ttl_secs)
+{
+    struct mroute_helper *mh;
+    ALLOC_OBJ_CLEAR(mh, struct mroute_helper);
+    mh->ageable_ttl_secs = ageable_ttl_secs;
+    return mh;
+}
+
+static void
+mroute_helper_regenerate(struct mroute_helper *mh)
+{
+    int i, j = 0;
+    for (i = MR_HELPER_NET_LEN - 1; i >= 0; --i)
+    {
+        if (mh->net_len_refcount[i] > 0)
+        {
+            mh->net_len[j++] = (uint8_t) i;
+        }
+    }
+    mh->n_net_len = j;
+
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_MULTI_DEBUG))
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer out = alloc_buf_gc(256, &gc);
+        buf_printf(&out, "MROUTE CIDR netlen:");
+        for (i = 0; i < mh->n_net_len; ++i)
+        {
+            buf_printf(&out, " /%d", mh->net_len[i]);
+        }
+        dmsg(D_MULTI_DEBUG, "%s", BSTR(&out));
+        gc_free(&gc);
+    }
+#endif
+}
+
+void
+mroute_helper_add_iroute46(struct mroute_helper *mh, int netbits)
+{
+    if (netbits >= 0)
+    {
+        ASSERT(netbits < MR_HELPER_NET_LEN);
+        ++mh->cache_generation;
+        ++mh->net_len_refcount[netbits];
+        if (mh->net_len_refcount[netbits] == 1)
+        {
+            mroute_helper_regenerate(mh);
+        }
+    }
+}
+
+void
+mroute_helper_del_iroute46(struct mroute_helper *mh, int netbits)
+{
+    if (netbits >= 0)
+    {
+        ASSERT(netbits < MR_HELPER_NET_LEN);
+        ++mh->cache_generation;
+        --mh->net_len_refcount[netbits];
+        ASSERT(mh->net_len_refcount[netbits] >= 0);
+        if (!mh->net_len_refcount[netbits])
+        {
+            mroute_helper_regenerate(mh);
+        }
+    }
+}
+
+void
+mroute_helper_free(struct mroute_helper *mh)
+{
+    free(mh);
+}
+
+#else  /* if P2MP_SERVER */
+static void
+dummy(void)
+{
+}
+#endif /* P2MP_SERVER */
diff --git a/src/openvpn/mroute.h b/src/openvpn/mroute.h
new file mode 100644
index 0000000..1063a18
--- /dev/null
+++ b/src/openvpn/mroute.h
@@ -0,0 +1,269 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MROUTE_H
+#define MROUTE_H
+
+#if P2MP_SERVER
+
+#include "buffer.h"
+#include "list.h"
+#include "route.h"
+
+#include <stddef.h>
+
+#define IP_MCAST_SUBNET_MASK  ((in_addr_t)240<<24)
+#define IP_MCAST_NETWORK      ((in_addr_t)224<<24)
+
+/* Return status values for mroute_extract_addr_from_packet */
+
+#define MROUTE_EXTRACT_SUCCEEDED (1<<0)
+#define MROUTE_EXTRACT_BCAST     (1<<1)
+#define MROUTE_EXTRACT_MCAST     (1<<2)
+#define MROUTE_EXTRACT_IGMP      (1<<3)
+
+#define MROUTE_SEC_EXTRACT_SUCCEEDED (1<<(0+MROUTE_SEC_SHIFT))
+#define MROUTE_SEC_EXTRACT_BCAST     (1<<(1+MROUTE_SEC_SHIFT))
+#define MROUTE_SEC_EXTRACT_MCAST     (1<<(2+MROUTE_SEC_SHIFT))
+#define MROUTE_SEC_EXTRACT_IGMP      (1<<(3+MROUTE_SEC_SHIFT))
+
+#define MROUTE_SEC_SHIFT         4
+
+/*
+ * Choose the largest address possible with
+ * any of our supported types, which is IPv6
+ * with port number.
+ */
+#define MR_MAX_ADDR_LEN 20
+
+/*
+ * Address Types
+ */
+#define MR_ADDR_NONE             0
+#define MR_ADDR_ETHER            1
+#define MR_ADDR_IPV4             2
+#define MR_ADDR_IPV6             3
+#define MR_ADDR_MASK             3
+
+/* Address type mask indicating that port # is part of address */
+#define MR_WITH_PORT             4
+
+/* Address type mask indicating that netbits is part of address */
+#define MR_WITH_NETBITS          8
+
+/* Indicates than IPv4 addr was extracted from ARP packet */
+#define MR_ARP                   16
+
+struct mroute_addr {
+    uint8_t len;    /* length of address */
+    uint8_t unused;
+    uint8_t type;   /* MR_ADDR/MR_WITH flags */
+    uint8_t netbits; /* number of bits in network part of address,
+                      * valid if MR_WITH_NETBITS is set */
+    union {
+        uint8_t raw_addr[MR_MAX_ADDR_LEN]; /* actual address */
+        uint8_t eth_addr[OPENVPN_ETH_ALEN];
+        struct {
+            in_addr_t addr;     /* _network order_ IPv4 address */
+            in_port_t port;     /* _network order_ TCP/UDP port */
+        } v4;
+        struct {
+            struct in6_addr addr;
+            in_port_t port;     /* _network order_ TCP/UDP port */
+        } v6;
+        struct {
+            uint8_t prefix[12];
+            in_addr_t addr;     /* _network order_ IPv4 address */
+        } v4mappedv6;
+    }
+#ifndef HAVE_ANONYMOUS_UNION_SUPPORT
+/* Wrappers to support compilers that do not grok anonymous unions */
+        mroute_union
+#define raw_addr mroute_union.raw_addr
+#define eth_addr mroute_union.eth_addr
+#define v4 mroute_union.v4
+#define v6 mroute_union.v6
+#define v4mappedv6 mroute_union.v4mappedv6
+#endif
+    ;
+};
+
+/* Double-check that struct packing works as expected */
+static_assert(offsetof(struct mroute_addr, v4.port) ==
+              offsetof(struct mroute_addr, v4) + 4,
+              "Unexpected struct packing of v4");
+static_assert(offsetof(struct mroute_addr, v6.port) ==
+              offsetof(struct mroute_addr, v6) + 16,
+              "Unexpected struct packing of v6");
+static_assert(offsetof(struct mroute_addr, v4mappedv6.addr) ==
+              offsetof(struct mroute_addr, v4mappedv6) + 12,
+              "Unexpected struct packing of v4mappedv6");
+
+/*
+ * Number of bits in an address.  Should be raised for IPv6.
+ */
+#define MR_HELPER_NET_LEN 129
+
+/*
+ * Used to help maintain CIDR routing table.
+ */
+struct mroute_helper {
+    unsigned int cache_generation; /* incremented when route added */
+    int ageable_ttl_secs;        /* host route cache entry time-to-live*/
+    int n_net_len;               /* length of net_len array */
+    uint8_t net_len[MR_HELPER_NET_LEN];    /* CIDR netlengths in descending order */
+    int net_len_refcount[MR_HELPER_NET_LEN]; /* refcount of each netlength */
+};
+
+struct openvpn_sockaddr;
+
+bool mroute_extract_openvpn_sockaddr(struct mroute_addr *addr,
+                                     const struct openvpn_sockaddr *osaddr,
+                                     bool use_port);
+
+bool mroute_learnable_address(const struct mroute_addr *addr,
+                              struct gc_arena *gc);
+
+uint32_t mroute_addr_hash_function(const void *key, uint32_t iv);
+
+bool mroute_addr_compare_function(const void *key1, const void *key2);
+
+void mroute_addr_init(struct mroute_addr *addr);
+
+const char *mroute_addr_print(const struct mroute_addr *ma,
+                              struct gc_arena *gc);
+
+#define MAPF_SUBNET            (1<<0)
+#define MAPF_IA_EMPTY_IF_UNDEF (1<<1)
+#define MAPF_SHOW_ARP          (1<<2)
+const char *mroute_addr_print_ex(const struct mroute_addr *ma,
+                                 const unsigned int flags,
+                                 struct gc_arena *gc);
+
+void mroute_addr_mask_host_bits(struct mroute_addr *ma);
+
+struct mroute_helper *mroute_helper_init(int ageable_ttl_secs);
+
+void mroute_helper_free(struct mroute_helper *mh);
+
+void mroute_helper_add_iroute46(struct mroute_helper *mh, int netbits);
+
+void mroute_helper_del_iroute46(struct mroute_helper *mh, int netbits);
+
+/*
+ * Given a raw packet in buf, return the src and dest
+ * addresses of the packet.
+ */
+static inline unsigned int
+mroute_extract_addr_from_packet(struct mroute_addr *src,
+                                struct mroute_addr *dest,
+                                struct mroute_addr *esrc,
+                                struct mroute_addr *edest,
+                                const struct buffer *buf,
+                                int tunnel_type)
+{
+    unsigned int mroute_extract_addr_ip(struct mroute_addr *src,
+                                     struct mroute_addr *dest,
+                                     const struct buffer *buf);
+
+    unsigned int mroute_extract_addr_ether(struct mroute_addr *src,
+                                           struct mroute_addr *dest,
+                                           struct mroute_addr *esrc,
+                                           struct mroute_addr *edest,
+                                           const struct buffer *buf);
+
+    unsigned int ret = 0;
+    verify_align_4(buf);
+    if (tunnel_type == DEV_TYPE_TUN)
+    {
+        ret = mroute_extract_addr_ip(src, dest, buf);
+    }
+    else if (tunnel_type == DEV_TYPE_TAP)
+    {
+        ret = mroute_extract_addr_ether(src, dest, esrc, edest, buf);
+    }
+    return ret;
+}
+
+static inline bool
+mroute_addr_equal(const struct mroute_addr *a1, const struct mroute_addr *a2)
+{
+    if (a1->type != a2->type)
+    {
+        return false;
+    }
+    if (a1->netbits != a2->netbits)
+    {
+        return false;
+    }
+    if (a1->len != a2->len)
+    {
+        return false;
+    }
+    return memcmp(a1->raw_addr, a2->raw_addr, a1->len) == 0;
+}
+
+static inline const uint8_t *
+mroute_addr_hash_ptr(const struct mroute_addr *a)
+{
+    /* NOTE: depends on ordering of struct mroute_addr */
+    return (uint8_t *) &a->type;
+}
+
+static inline uint32_t
+mroute_addr_hash_len(const struct mroute_addr *a)
+{
+    return (uint32_t) a->len + 2;
+}
+
+static inline void
+mroute_extract_in_addr_t(struct mroute_addr *dest, const in_addr_t src)
+{
+    dest->type = MR_ADDR_IPV4;
+    dest->netbits = 0;
+    dest->len = 4;
+    dest->v4.addr = htonl(src);
+}
+
+static inline in_addr_t
+in_addr_t_from_mroute_addr(const struct mroute_addr *addr)
+{
+    if ((addr->type & MR_ADDR_MASK) == MR_ADDR_IPV4 && addr->netbits == 0 && addr->len == 4)
+    {
+        return ntohl(addr->v4.addr);
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline void
+mroute_addr_reset(struct mroute_addr *ma)
+{
+    ma->len = 0;
+    ma->type = MR_ADDR_NONE;
+}
+
+#endif /* P2MP_SERVER */
+#endif /* MROUTE_H */
diff --git a/src/openvpn/mss.c b/src/openvpn/mss.c
new file mode 100644
index 0000000..facdf7b
--- /dev/null
+++ b/src/openvpn/mss.c
@@ -0,0 +1,206 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "error.h"
+#include "mss.h"
+#include "memdbg.h"
+
+/*
+ * Lower MSS on TCP SYN packets to fix MTU
+ * problems which arise from protocol
+ * encapsulation.
+ */
+
+/*
+ * IPv4 packet: find TCP header, check flags for "SYN"
+ *              if yes, hand to mss_fixup_dowork()
+ */
+void
+mss_fixup_ipv4(struct buffer *buf, int maxmss)
+{
+    const struct openvpn_iphdr *pip;
+    int hlen;
+
+    if (BLEN(buf) < (int) sizeof(struct openvpn_iphdr))
+    {
+        return;
+    }
+
+    verify_align_4(buf);
+    pip = (struct openvpn_iphdr *) BPTR(buf);
+
+    hlen = OPENVPN_IPH_GET_LEN(pip->version_len);
+
+    if (pip->protocol == OPENVPN_IPPROTO_TCP
+        && ntohs(pip->tot_len) == BLEN(buf)
+        && (ntohs(pip->frag_off) & OPENVPN_IP_OFFMASK) == 0
+        && hlen <= BLEN(buf)
+        && BLEN(buf) - hlen
+        >= (int) sizeof(struct openvpn_tcphdr))
+    {
+        struct buffer newbuf = *buf;
+        if (buf_advance(&newbuf, hlen))
+        {
+            struct openvpn_tcphdr *tc = (struct openvpn_tcphdr *) BPTR(&newbuf);
+            if (tc->flags & OPENVPN_TCPH_SYN_MASK)
+            {
+                mss_fixup_dowork(&newbuf, (uint16_t) maxmss);
+            }
+        }
+    }
+}
+
+/*
+ * IPv6 packet: find TCP header, check flags for "SYN"
+ *              if yes, hand to mss_fixup_dowork()
+ *              (IPv6 header structure is sufficiently different from IPv4...)
+ */
+void
+mss_fixup_ipv6(struct buffer *buf, int maxmss)
+{
+    const struct openvpn_ipv6hdr *pip6;
+    struct buffer newbuf;
+
+    if (BLEN(buf) < (int) sizeof(struct openvpn_ipv6hdr))
+    {
+        return;
+    }
+
+    verify_align_4(buf);
+    pip6 = (struct openvpn_ipv6hdr *) BPTR(buf);
+
+    /* do we have the full IPv6 packet?
+     * "payload_len" does not include IPv6 header (+40 bytes)
+     */
+    if (BLEN(buf) != (int) ntohs(pip6->payload_len)+40)
+    {
+        return;
+    }
+
+    /* follow header chain until we reach final header, then check for TCP
+     *
+     * An IPv6 packet could, theoretically, have a chain of multiple headers
+     * before the final header (TCP, UDP, ...), so we'd need to walk that
+     * chain (see RFC 2460 and RFC 6564 for details).
+     *
+     * In practice, "most typically used" extention headers (AH, routing,
+     * fragment, mobility) are very unlikely to be seen inside an OpenVPN
+     * tun, so for now, we only handle the case of "single next header = TCP"
+     */
+    if (pip6->nexthdr != OPENVPN_IPPROTO_TCP)
+    {
+        return;
+    }
+
+    /* skip IPv6 header (40 bytes),
+     * verify remainder is large enough to contain a full TCP header
+     */
+    newbuf = *buf;
+    if (buf_advance( &newbuf, 40 )
+        && BLEN(&newbuf) >= (int) sizeof(struct openvpn_tcphdr))
+    {
+        struct openvpn_tcphdr *tc = (struct openvpn_tcphdr *) BPTR(&newbuf);
+        if (tc->flags & OPENVPN_TCPH_SYN_MASK)
+        {
+            mss_fixup_dowork(&newbuf, (uint16_t) maxmss-20);
+        }
+    }
+}
+
+/*
+ * change TCP MSS option in SYN/SYN-ACK packets, if present
+ * this is generic for IPv4 and IPv6, as the TCP header is the same
+ */
+
+void
+mss_fixup_dowork(struct buffer *buf, uint16_t maxmss)
+{
+    int hlen, olen, optlen;
+    uint8_t *opt;
+    uint16_t mssval;
+    int accumulate;
+    struct openvpn_tcphdr *tc;
+
+    if (BLEN(buf) < (int) sizeof(struct openvpn_tcphdr))
+    {
+	return;
+    }
+
+    verify_align_4(buf);
+    tc = (struct openvpn_tcphdr *) BPTR(buf);
+    hlen = OPENVPN_TCPH_GET_DOFF(tc->doff_res);
+
+    /* Invalid header length or header without options. */
+    if (hlen <= (int) sizeof(struct openvpn_tcphdr)
+        || hlen > BLEN(buf))
+    {
+        return;
+    }
+
+    for (olen = hlen - sizeof(struct openvpn_tcphdr),
+         opt = (uint8_t *)(tc + 1);
+         olen > 1;
+         olen -= optlen, opt += optlen)
+    {
+        if (*opt == OPENVPN_TCPOPT_EOL)
+        {
+            break;
+        }
+        else if (*opt == OPENVPN_TCPOPT_NOP)
+        {
+            optlen = 1;
+        }
+        else
+        {
+            optlen = *(opt + 1);
+            if (optlen <= 0 || optlen > olen)
+            {
+                break;
+            }
+            if (*opt == OPENVPN_TCPOPT_MAXSEG)
+            {
+                if (optlen != OPENVPN_TCPOLEN_MAXSEG)
+                {
+                    continue;
+                }
+                mssval = (opt[2]<<8)+opt[3];
+                if (mssval > maxmss)
+                {
+                    dmsg(D_MSS, "MSS: %d -> %d", (int) mssval, (int) maxmss);
+                    accumulate = htons(mssval);
+                    opt[2] = (maxmss>>8)&0xff;
+                    opt[3] = maxmss&0xff;
+                    accumulate -= htons(maxmss);
+                    ADJUST_CHECKSUM(accumulate, tc->check);
+                }
+            }
+        }
+    }
+}
diff --git a/src/openvpn/mss.h b/src/openvpn/mss.h
new file mode 100644
index 0000000..9350102
--- /dev/null
+++ b/src/openvpn/mss.h
@@ -0,0 +1,36 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MSS_H
+#define MSS_H
+
+#include "proto.h"
+#include "error.h"
+
+void mss_fixup_ipv4(struct buffer *buf, int maxmss);
+
+void mss_fixup_ipv6(struct buffer *buf, int maxmss);
+
+void mss_fixup_dowork(struct buffer *buf, uint16_t maxmss);
+
+#endif
diff --git a/src/openvpn/mstats.c b/src/openvpn/mstats.c
new file mode 100644
index 0000000..281a835
--- /dev/null
+++ b/src/openvpn/mstats.c
@@ -0,0 +1,127 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Maintain usage stats in a memory-mapped file
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_MEMSTATS)
+
+#include <sys/mman.h>
+
+#include "error.h"
+#include "misc.h"
+#include "mstats.h"
+
+#include "memdbg.h"
+
+volatile struct mmap_stats *mmap_stats = NULL; /* GLOBAL */
+static char mmap_fn[128];
+
+void
+mstats_open(const char *fn)
+{
+    void *data;
+    ssize_t stat;
+    int fd;
+    struct mmap_stats ms;
+
+    if (mmap_stats) /* already called? */
+    {
+        return;
+    }
+
+    /* verify that filename is not too long */
+    if (strlen(fn) >= sizeof(mmap_fn))
+    {
+        msg(M_FATAL, "mstats_open: filename too long");
+    }
+
+    /* create file that will be memory mapped */
+    fd = open(fn, O_CREAT | O_TRUNC | O_RDWR, S_IRUSR | S_IWUSR);
+    if (fd < 0)
+    {
+        msg(M_ERR, "mstats_open: cannot open: %s", fn);
+        return;
+    }
+
+    /* set the file to the correct size to contain a
+     * struct mmap_stats, and zero it */
+    CLEAR(ms);
+    ms.state = MSTATS_ACTIVE;
+    stat = write(fd, &ms, sizeof(ms));
+    if (stat != sizeof(ms))
+    {
+        msg(M_ERR, "mstats_open: write error: %s", fn);
+        close(fd);
+        return;
+    }
+
+    /* mmap the file */
+    data = mmap(NULL, sizeof(struct mmap_stats), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
+    if (data == MAP_FAILED)
+    {
+        msg(M_ERR, "mstats_open: write error: %s", fn);
+        close(fd);
+        return;
+    }
+
+    /* close the fd (mmap now controls the file) */
+    if (close(fd))
+    {
+        msg(M_ERR, "mstats_open: close error: %s", fn);
+    }
+
+    /* save filename so we can delete it later */
+    strcpy(mmap_fn, fn);
+
+    /* save a global pointer to memory-mapped region */
+    mmap_stats = (struct mmap_stats *)data;
+
+    msg(M_INFO, "memstats data will be written to %s", fn);
+}
+
+void
+mstats_close(void)
+{
+    if (mmap_stats)
+    {
+        mmap_stats->state = MSTATS_EXPIRED;
+        if (munmap((void *)mmap_stats, sizeof(struct mmap_stats)))
+        {
+            msg(M_WARN | M_ERRNO, "mstats_close: munmap error");
+        }
+        platform_unlink(mmap_fn);
+        mmap_stats = NULL;
+    }
+}
+
+#endif /* if defined(ENABLE_MEMSTATS) */
diff --git a/src/openvpn/mstats.h b/src/openvpn/mstats.h
new file mode 100644
index 0000000..0d58cbf
--- /dev/null
+++ b/src/openvpn/mstats.h
@@ -0,0 +1,51 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Maintain usage stats in a memory-mapped file
+ */
+
+#if !defined(OPENVPN_MEMSTATS_H) && defined(ENABLE_MEMSTATS)
+#define OPENVPN_MEMSTATS_H
+
+#include "basic.h"
+
+/* this struct is mapped to the file */
+struct mmap_stats {
+    counter_type link_read_bytes; /* counter_type can be assumed to be a uint64_t */
+    counter_type link_write_bytes;
+    int n_clients;
+
+#define MSTATS_UNDEF   0
+#define MSTATS_ACTIVE  1
+#define MSTATS_EXPIRED 2
+    int state;
+};
+
+extern volatile struct mmap_stats *mmap_stats; /* GLOBAL */
+
+void mstats_open(const char *fn);
+
+void mstats_close(void);
+
+#endif /* if !defined(OPENVPN_MEMSTATS_H) && defined(ENABLE_MEMSTATS) */
diff --git a/src/openvpn/mtcp.c b/src/openvpn/mtcp.c
new file mode 100644
index 0000000..e8d2add
--- /dev/null
+++ b/src/openvpn/mtcp.c
@@ -0,0 +1,848 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "multi.h"
+#include "forward-inline.h"
+
+#include "memdbg.h"
+
+#ifdef HAVE_SYS_INOTIFY_H
+#include <sys/inotify.h>
+#endif
+
+/*
+ * TCP States
+ */
+#define TA_UNDEF                 0
+#define TA_SOCKET_READ           1
+#define TA_SOCKET_READ_RESIDUAL  2
+#define TA_SOCKET_WRITE          3
+#define TA_SOCKET_WRITE_READY    4
+#define TA_SOCKET_WRITE_DEFERRED 5
+#define TA_TUN_READ              6
+#define TA_TUN_WRITE             7
+#define TA_INITIAL               8
+#define TA_TIMEOUT               9
+#define TA_TUN_WRITE_TIMEOUT     10
+
+/*
+ * Special tags passed to event.[ch] functions
+ */
+#define MTCP_SOCKET      ((void *)1)
+#define MTCP_TUN         ((void *)2)
+#define MTCP_SIG         ((void *)3) /* Only on Windows */
+#ifdef ENABLE_MANAGEMENT
+#define MTCP_MANAGEMENT ((void *)4)
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+#define MTCP_FILE_CLOSE_WRITE ((void *)5)
+#endif
+
+#define MTCP_N           ((void *)16) /* upper bound on MTCP_x */
+
+struct ta_iow_flags
+{
+    unsigned int flags;
+    unsigned int ret;
+    unsigned int tun;
+    unsigned int sock;
+};
+
+static const char *
+pract(int action)
+{
+    switch (action)
+    {
+        case TA_UNDEF:
+            return "TA_UNDEF";
+
+        case TA_SOCKET_READ:
+            return "TA_SOCKET_READ";
+
+        case TA_SOCKET_READ_RESIDUAL:
+            return "TA_SOCKET_READ_RESIDUAL";
+
+        case TA_SOCKET_WRITE:
+            return "TA_SOCKET_WRITE";
+
+        case TA_SOCKET_WRITE_READY:
+            return "TA_SOCKET_WRITE_READY";
+
+        case TA_SOCKET_WRITE_DEFERRED:
+            return "TA_SOCKET_WRITE_DEFERRED";
+
+        case TA_TUN_READ:
+            return "TA_TUN_READ";
+
+        case TA_TUN_WRITE:
+            return "TA_TUN_WRITE";
+
+        case TA_INITIAL:
+            return "TA_INITIAL";
+
+        case TA_TIMEOUT:
+            return "TA_TIMEOUT";
+
+        case TA_TUN_WRITE_TIMEOUT:
+            return "TA_TUN_WRITE_TIMEOUT";
+
+        default:
+            return "?";
+    }
+}
+
+static struct multi_instance *
+multi_create_instance_tcp(struct multi_context *m)
+{
+    struct gc_arena gc = gc_new();
+    struct multi_instance *mi = NULL;
+    struct hash *hash = m->hash;
+
+    mi = multi_create_instance(m, NULL);
+    if (mi)
+    {
+        struct hash_element *he;
+        const uint32_t hv = hash_value(hash, &mi->real);
+        struct hash_bucket *bucket = hash_bucket(hash, hv);
+
+        he = hash_lookup_fast(hash, bucket, &mi->real, hv);
+
+        if (he)
+        {
+            struct multi_instance *oldmi = (struct multi_instance *) he->value;
+            msg(D_MULTI_LOW, "MULTI TCP: new incoming client address matches existing client address -- new client takes precedence");
+            oldmi->did_real_hash = false;
+            multi_close_instance(m, oldmi, false);
+            he->key = &mi->real;
+            he->value = mi;
+        }
+        else
+        {
+            hash_add_fast(hash, bucket, &mi->real, hv, mi);
+        }
+
+        mi->did_real_hash = true;
+    }
+
+#ifdef ENABLE_DEBUG
+    if (mi)
+    {
+        dmsg(D_MULTI_DEBUG, "MULTI TCP: instance added: %s", mroute_addr_print(&mi->real, &gc));
+    }
+    else
+    {
+        dmsg(D_MULTI_DEBUG, "MULTI TCP: new client instance failed");
+    }
+#endif
+
+    gc_free(&gc);
+    ASSERT(!(mi && mi->halt));
+    return mi;
+}
+
+bool
+multi_tcp_instance_specific_init(struct multi_context *m, struct multi_instance *mi)
+{
+    /* buffer for queued TCP socket output packets */
+    mi->tcp_link_out_deferred = mbuf_init(m->top.options.n_bcast_buf);
+
+    ASSERT(mi->context.c2.link_socket);
+    ASSERT(mi->context.c2.link_socket->info.lsa);
+    ASSERT(mi->context.c2.link_socket->mode == LS_MODE_TCP_ACCEPT_FROM);
+    ASSERT(mi->context.c2.link_socket->info.lsa->actual.dest.addr.sa.sa_family == AF_INET
+           || mi->context.c2.link_socket->info.lsa->actual.dest.addr.sa.sa_family == AF_INET6
+           );
+    if (!mroute_extract_openvpn_sockaddr(&mi->real, &mi->context.c2.link_socket->info.lsa->actual.dest, true))
+    {
+        msg(D_MULTI_ERRORS, "MULTI TCP: TCP client address is undefined");
+        return false;
+    }
+    return true;
+}
+
+void
+multi_tcp_instance_specific_free(struct multi_instance *mi)
+{
+    mbuf_free(mi->tcp_link_out_deferred);
+}
+
+struct multi_tcp *
+multi_tcp_init(int maxevents, int *maxclients)
+{
+    struct multi_tcp *mtcp;
+    const int extra_events = BASE_N_EVENTS;
+
+    ASSERT(maxevents >= 1);
+    ASSERT(maxclients);
+
+    ALLOC_OBJ_CLEAR(mtcp, struct multi_tcp);
+    mtcp->maxevents = maxevents + extra_events;
+    mtcp->es = event_set_init(&mtcp->maxevents, 0);
+    wait_signal(mtcp->es, MTCP_SIG);
+    ALLOC_ARRAY(mtcp->esr, struct event_set_return, mtcp->maxevents);
+    *maxclients = max_int(min_int(mtcp->maxevents - extra_events, *maxclients), 1);
+    msg(D_MULTI_LOW, "MULTI: TCP INIT maxclients=%d maxevents=%d", *maxclients, mtcp->maxevents);
+    return mtcp;
+}
+
+void
+multi_tcp_delete_event(struct multi_tcp *mtcp, event_t event)
+{
+    if (mtcp && mtcp->es)
+    {
+        event_del(mtcp->es, event);
+    }
+}
+
+void
+multi_tcp_free(struct multi_tcp *mtcp)
+{
+    if (mtcp)
+    {
+        event_free(mtcp->es);
+        if (mtcp->esr)
+        {
+            free(mtcp->esr);
+        }
+        free(mtcp);
+    }
+}
+
+void
+multi_tcp_dereference_instance(struct multi_tcp *mtcp, struct multi_instance *mi)
+{
+    struct link_socket *ls = mi->context.c2.link_socket;
+    if (ls && mi->socket_set_called)
+    {
+        event_del(mtcp->es, socket_event_handle(ls));
+    }
+    mtcp->n_esr = 0;
+}
+
+static inline void
+multi_tcp_set_global_rw_flags(struct multi_context *m, struct multi_instance *mi)
+{
+    if (mi)
+    {
+        mi->socket_set_called = true;
+        socket_set(mi->context.c2.link_socket,
+                   m->mtcp->es,
+                   mbuf_defined(mi->tcp_link_out_deferred) ? EVENT_WRITE : EVENT_READ,
+                   mi,
+                   &mi->tcp_rwflags);
+    }
+}
+
+static inline int
+multi_tcp_wait(const struct context *c,
+               struct multi_tcp *mtcp)
+{
+    int status;
+    socket_set_listen_persistent(c->c2.link_socket, mtcp->es, MTCP_SOCKET);
+    tun_set(c->c1.tuntap, mtcp->es, EVENT_READ, MTCP_TUN, &mtcp->tun_rwflags);
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        management_socket_set(management, mtcp->es, MTCP_MANAGEMENT, &mtcp->management_persist_flags);
+    }
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+    /* arm inotify watcher */
+    event_ctl(mtcp->es, c->c2.inotify_fd, EVENT_READ, MTCP_FILE_CLOSE_WRITE);
+#endif
+
+    status = event_wait(mtcp->es, &c->c2.timeval, mtcp->esr, mtcp->maxevents);
+    update_time();
+    mtcp->n_esr = 0;
+    if (status > 0)
+    {
+        mtcp->n_esr = status;
+    }
+    return status;
+}
+
+static inline struct context *
+multi_tcp_context(struct multi_context *m, struct multi_instance *mi)
+{
+    if (mi)
+    {
+        return &mi->context;
+    }
+    else
+    {
+        return &m->top;
+    }
+}
+
+static bool
+multi_tcp_process_outgoing_link_ready(struct multi_context *m, struct multi_instance *mi, const unsigned int mpp_flags)
+{
+    struct mbuf_item item;
+    bool ret = true;
+    ASSERT(mi);
+
+    /* extract from queue */
+    if (mbuf_extract_item(mi->tcp_link_out_deferred, &item)) /* ciphertext IP packet */
+    {
+        dmsg(D_MULTI_TCP, "MULTI TCP: transmitting previously deferred packet");
+
+        ASSERT(mi == item.instance);
+        mi->context.c2.to_link = item.buffer->buf;
+        ret = multi_process_outgoing_link_dowork(m, mi, mpp_flags);
+        if (!ret)
+        {
+            mi = NULL;
+        }
+        mbuf_free_buf(item.buffer);
+    }
+    return ret;
+}
+
+static bool
+multi_tcp_process_outgoing_link(struct multi_context *m, bool defer, const unsigned int mpp_flags)
+{
+    struct multi_instance *mi = multi_process_outgoing_link_pre(m);
+    bool ret = true;
+
+    if (mi)
+    {
+        if (defer || mbuf_defined(mi->tcp_link_out_deferred))
+        {
+            /* save to queue */
+            struct buffer *buf = &mi->context.c2.to_link;
+            if (BLEN(buf) > 0)
+            {
+                struct mbuf_buffer *mb = mbuf_alloc_buf(buf);
+                struct mbuf_item item;
+
+                set_prefix(mi);
+                dmsg(D_MULTI_TCP, "MULTI TCP: queuing deferred packet");
+                item.buffer = mb;
+                item.instance = mi;
+                mbuf_add_item(mi->tcp_link_out_deferred, &item);
+                mbuf_free_buf(mb);
+                buf_reset(buf);
+                ret = multi_process_post(m, mi, mpp_flags);
+                if (!ret)
+                {
+                    mi = NULL;
+                }
+                clear_prefix();
+            }
+        }
+        else
+        {
+            ret = multi_process_outgoing_link_dowork(m, mi, mpp_flags);
+            if (!ret)
+            {
+                mi = NULL;
+            }
+        }
+    }
+    return ret;
+}
+
+static int
+multi_tcp_wait_lite(struct multi_context *m, struct multi_instance *mi, const int action, bool *tun_input_pending)
+{
+    struct context *c = multi_tcp_context(m, mi);
+    unsigned int looking_for = 0;
+
+    dmsg(D_MULTI_DEBUG, "MULTI TCP: multi_tcp_wait_lite a=%s mi=" ptr_format,
+         pract(action),
+         (ptr_type)mi);
+
+    tv_clear(&c->c2.timeval); /* ZERO-TIMEOUT */
+
+    switch (action)
+    {
+        case TA_TUN_READ:
+            looking_for = TUN_READ;
+            tun_input_pending = NULL;
+            io_wait(c, IOW_READ_TUN);
+            break;
+
+        case TA_SOCKET_READ:
+            looking_for = SOCKET_READ;
+            tun_input_pending = NULL;
+            io_wait(c, IOW_READ_LINK);
+            break;
+
+        case TA_TUN_WRITE:
+            looking_for = TUN_WRITE;
+            tun_input_pending = NULL;
+            c->c2.timeval.tv_sec = 1; /* For some reason, the Linux 2.2 TUN/TAP driver hits this timeout */
+            perf_push(PERF_PROC_OUT_TUN_MTCP);
+            io_wait(c, IOW_TO_TUN);
+            perf_pop();
+            break;
+
+        case TA_SOCKET_WRITE:
+            looking_for = SOCKET_WRITE;
+            io_wait(c, IOW_TO_LINK|IOW_READ_TUN_FORCE);
+            break;
+
+        default:
+            msg(M_FATAL, "MULTI TCP: multi_tcp_wait_lite, unhandled action=%d", action);
+    }
+
+    if (tun_input_pending && (c->c2.event_set_status & TUN_READ))
+    {
+        *tun_input_pending = true;
+    }
+
+    if (c->c2.event_set_status & looking_for)
+    {
+        return action;
+    }
+    else
+    {
+        switch (action)
+        {
+            /* TCP socket output buffer is full */
+            case TA_SOCKET_WRITE:
+                return TA_SOCKET_WRITE_DEFERRED;
+
+            /* TUN device timed out on accepting write */
+            case TA_TUN_WRITE:
+                return TA_TUN_WRITE_TIMEOUT;
+        }
+
+        return TA_UNDEF;
+    }
+}
+
+static struct multi_instance *
+multi_tcp_dispatch(struct multi_context *m, struct multi_instance *mi, const int action)
+{
+    const unsigned int mpp_flags = MPP_PRE_SELECT|MPP_RECORD_TOUCH;
+    struct multi_instance *touched = mi;
+    m->mpp_touched = &touched;
+
+    dmsg(D_MULTI_DEBUG, "MULTI TCP: multi_tcp_dispatch a=%s mi=" ptr_format,
+         pract(action),
+         (ptr_type)mi);
+
+    switch (action)
+    {
+        case TA_TUN_READ:
+            read_incoming_tun(&m->top);
+            if (!IS_SIG(&m->top))
+            {
+                multi_process_incoming_tun(m, mpp_flags);
+            }
+            break;
+
+        case TA_SOCKET_READ:
+        case TA_SOCKET_READ_RESIDUAL:
+            ASSERT(mi);
+            ASSERT(mi->context.c2.link_socket);
+            set_prefix(mi);
+            read_incoming_link(&mi->context);
+            clear_prefix();
+            if (!IS_SIG(&mi->context))
+            {
+                multi_process_incoming_link(m, mi, mpp_flags);
+                if (!IS_SIG(&mi->context))
+                {
+                    stream_buf_read_setup(mi->context.c2.link_socket);
+                }
+            }
+            break;
+
+        case TA_TIMEOUT:
+            multi_process_timeout(m, mpp_flags);
+            break;
+
+        case TA_TUN_WRITE:
+            multi_process_outgoing_tun(m, mpp_flags);
+            break;
+
+        case TA_TUN_WRITE_TIMEOUT:
+            multi_process_drop_outgoing_tun(m, mpp_flags);
+            break;
+
+        case TA_SOCKET_WRITE_READY:
+            ASSERT(mi);
+            multi_tcp_process_outgoing_link_ready(m, mi, mpp_flags);
+            break;
+
+        case TA_SOCKET_WRITE:
+            multi_tcp_process_outgoing_link(m, false, mpp_flags);
+            break;
+
+        case TA_SOCKET_WRITE_DEFERRED:
+            multi_tcp_process_outgoing_link(m, true, mpp_flags);
+            break;
+
+        case TA_INITIAL:
+            ASSERT(mi);
+            multi_tcp_set_global_rw_flags(m, mi);
+            multi_process_post(m, mi, mpp_flags);
+            break;
+
+        default:
+            msg(M_FATAL, "MULTI TCP: multi_tcp_dispatch, unhandled action=%d", action);
+    }
+
+    m->mpp_touched = NULL;
+    return touched;
+}
+
+static int
+multi_tcp_post(struct multi_context *m, struct multi_instance *mi, const int action)
+{
+    struct context *c = multi_tcp_context(m, mi);
+    int newaction = TA_UNDEF;
+
+#define MTP_NONE         0
+#define MTP_TUN_OUT      (1<<0)
+#define MTP_LINK_OUT     (1<<1)
+    unsigned int flags = MTP_NONE;
+
+    if (TUN_OUT(c))
+    {
+        flags |= MTP_TUN_OUT;
+    }
+    if (LINK_OUT(c))
+    {
+        flags |= MTP_LINK_OUT;
+    }
+
+    switch (flags)
+    {
+        case MTP_TUN_OUT|MTP_LINK_OUT:
+        case MTP_TUN_OUT:
+            newaction = TA_TUN_WRITE;
+            break;
+
+        case MTP_LINK_OUT:
+            newaction = TA_SOCKET_WRITE;
+            break;
+
+        case MTP_NONE:
+            if (mi && socket_read_residual(c->c2.link_socket))
+            {
+                newaction = TA_SOCKET_READ_RESIDUAL;
+            }
+            else
+            {
+                multi_tcp_set_global_rw_flags(m, mi);
+            }
+            break;
+
+        default:
+        {
+            struct gc_arena gc = gc_new();
+            msg(M_FATAL, "MULTI TCP: multi_tcp_post bad state, mi=%s flags=%d",
+                multi_instance_string(mi, false, &gc),
+                flags);
+            gc_free(&gc);
+            break;
+        }
+    }
+
+    dmsg(D_MULTI_DEBUG, "MULTI TCP: multi_tcp_post %s -> %s",
+         pract(action),
+         pract(newaction));
+
+    return newaction;
+}
+
+static void
+multi_tcp_action(struct multi_context *m, struct multi_instance *mi, int action, bool poll)
+{
+    bool tun_input_pending = false;
+
+    do
+    {
+        dmsg(D_MULTI_DEBUG, "MULTI TCP: multi_tcp_action a=%s p=%d",
+             pract(action),
+             poll);
+
+        /*
+         * If TA_SOCKET_READ_RESIDUAL, it means we still have pending
+         * input packets which were read by a prior TCP recv.
+         *
+         * Otherwise do a "lite" wait, which means we wait with 0 timeout
+         * on I/O events only related to the current instance, not
+         * the big list of events.
+         *
+         * On our first pass, poll will be false because we already know
+         * that input is available, and to call io_wait would be redundant.
+         */
+        if (poll && action != TA_SOCKET_READ_RESIDUAL)
+        {
+            const int orig_action = action;
+            action = multi_tcp_wait_lite(m, mi, action, &tun_input_pending);
+            if (action == TA_UNDEF)
+            {
+                msg(M_FATAL, "MULTI TCP: I/O wait required blocking in multi_tcp_action, action=%d", orig_action);
+            }
+        }
+
+        /*
+         * Dispatch the action
+         */
+        {
+            struct multi_instance *touched = multi_tcp_dispatch(m, mi, action);
+
+            /*
+             * Signal received or TCP connection
+             * reset by peer?
+             */
+            if (touched && IS_SIG(&touched->context))
+            {
+                if (mi == touched)
+                {
+                    mi = NULL;
+                }
+                multi_close_instance_on_signal(m, touched);
+            }
+        }
+
+        /*
+         * If dispatch produced any pending output
+         * for a particular instance, point to
+         * that instance.
+         */
+        if (m->pending)
+        {
+            mi = m->pending;
+        }
+
+        /*
+         * Based on the effects of the action,
+         * such as generating pending output,
+         * possibly transition to a new action state.
+         */
+        action = multi_tcp_post(m, mi, action);
+
+        /*
+         * If we are finished processing the original action,
+         * check if we have any TUN input.  If so, transition
+         * our action state to processing this input.
+         */
+        if (tun_input_pending && action == TA_UNDEF)
+        {
+            action = TA_TUN_READ;
+            mi = NULL;
+            tun_input_pending = false;
+            poll = false;
+        }
+        else
+        {
+            poll = true;
+        }
+
+    } while (action != TA_UNDEF);
+}
+
+static void
+multi_tcp_process_io(struct multi_context *m)
+{
+    struct multi_tcp *mtcp = m->mtcp;
+    int i;
+
+    for (i = 0; i < mtcp->n_esr; ++i)
+    {
+        struct event_set_return *e = &mtcp->esr[i];
+
+        /* incoming data for instance? */
+        if (e->arg >= MTCP_N)
+        {
+            struct multi_instance *mi = (struct multi_instance *) e->arg;
+            if (mi)
+            {
+                if (e->rwflags & EVENT_WRITE)
+                {
+                    multi_tcp_action(m, mi, TA_SOCKET_WRITE_READY, false);
+                }
+                else if (e->rwflags & EVENT_READ)
+                {
+                    multi_tcp_action(m, mi, TA_SOCKET_READ, false);
+                }
+            }
+        }
+        else
+        {
+#ifdef ENABLE_MANAGEMENT
+            if (e->arg == MTCP_MANAGEMENT)
+            {
+                ASSERT(management);
+                management_io(management);
+            }
+            else
+#endif
+            /* incoming data on TUN? */
+            if (e->arg == MTCP_TUN)
+            {
+                if (e->rwflags & EVENT_WRITE)
+                {
+                    multi_tcp_action(m, NULL, TA_TUN_WRITE, false);
+                }
+                else if (e->rwflags & EVENT_READ)
+                {
+                    multi_tcp_action(m, NULL, TA_TUN_READ, false);
+                }
+            }
+            /* new incoming TCP client attempting to connect? */
+            else if (e->arg == MTCP_SOCKET)
+            {
+                struct multi_instance *mi;
+                ASSERT(m->top.c2.link_socket);
+                socket_reset_listen_persistent(m->top.c2.link_socket);
+                mi = multi_create_instance_tcp(m);
+                if (mi)
+                {
+                    multi_tcp_action(m, mi, TA_INITIAL, false);
+                }
+            }
+            /* signal received? */
+            else if (e->arg == MTCP_SIG)
+            {
+                get_signal(&m->top.sig->signal_received);
+            }
+#ifdef ENABLE_ASYNC_PUSH
+            else if (e->arg == MTCP_FILE_CLOSE_WRITE)
+            {
+                multi_process_file_closed(m, MPP_PRE_SELECT | MPP_RECORD_TOUCH);
+            }
+#endif
+        }
+        if (IS_SIG(&m->top))
+        {
+            break;
+        }
+    }
+    mtcp->n_esr = 0;
+
+    /*
+     * Process queued mbuf packets destined for TCP socket
+     */
+    {
+        struct multi_instance *mi;
+        while (!IS_SIG(&m->top) && (mi = mbuf_peek(m->mbuf)) != NULL)
+        {
+            multi_tcp_action(m, mi, TA_SOCKET_WRITE, true);
+        }
+    }
+}
+
+/*
+ * Top level event loop for single-threaded operation.
+ * TCP mode.
+ */
+void
+tunnel_server_tcp(struct context *top)
+{
+    struct multi_context multi;
+    int status;
+
+    top->mode = CM_TOP;
+    context_clear_2(top);
+
+    /* initialize top-tunnel instance */
+    init_instance_handle_signals(top, top->es, CC_HARD_USR1_TO_HUP);
+    if (IS_SIG(top))
+    {
+        return;
+    }
+
+    /* initialize global multi_context object */
+    multi_init(&multi, top, true, MC_SINGLE_THREADED);
+
+    /* initialize our cloned top object */
+    multi_top_init(&multi, top);
+
+    /* initialize management interface */
+    init_management_callback_multi(&multi);
+
+    /* finished with initialization */
+    initialization_sequence_completed(top, ISC_SERVER); /* --mode server --proto tcp-server */
+
+#ifdef ENABLE_ASYNC_PUSH
+    multi.top.c2.inotify_fd = inotify_init();
+    if (multi.top.c2.inotify_fd < 0)
+    {
+        msg(D_MULTI_ERRORS | M_ERRNO, "MULTI: inotify_init error");
+    }
+#endif
+
+    /* per-packet event loop */
+    while (true)
+    {
+        perf_push(PERF_EVENT_LOOP);
+
+        /* wait on tun/socket list */
+        multi_get_timeout(&multi, &multi.top.c2.timeval);
+        status = multi_tcp_wait(&multi.top, multi.mtcp);
+        MULTI_CHECK_SIG(&multi);
+
+        /* check on status of coarse timers */
+        multi_process_per_second_timers(&multi);
+
+        /* timeout? */
+        if (status > 0)
+        {
+            /* process the I/O which triggered select */
+            multi_tcp_process_io(&multi);
+            MULTI_CHECK_SIG(&multi);
+        }
+        else if (status == 0)
+        {
+            multi_tcp_action(&multi, NULL, TA_TIMEOUT, false);
+        }
+
+        perf_pop();
+    }
+
+#ifdef ENABLE_ASYNC_PUSH
+    close(top->c2.inotify_fd);
+#endif
+
+    /* shut down management interface */
+    uninit_management_callback();
+
+    /* save ifconfig-pool */
+    multi_ifconfig_pool_persist(&multi, true);
+
+    /* tear down tunnel instance (unless --persist-tun) */
+    multi_uninit(&multi);
+    multi_top_free(&multi);
+    close_instance(top);
+}
+
+#endif /* if P2MP_SERVER */
diff --git a/src/openvpn/mtcp.h b/src/openvpn/mtcp.h
new file mode 100644
index 0000000..bba455b
--- /dev/null
+++ b/src/openvpn/mtcp.h
@@ -0,0 +1,79 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * TCP specific code for --mode server
+ */
+
+#ifndef MTCP_H
+#define MTCP_H
+
+#if P2MP_SERVER
+
+#include "event.h"
+
+/*
+ * Extra state info needed for TCP mode
+ */
+struct multi_tcp
+{
+    struct event_set *es;
+    struct event_set_return *esr;
+    int n_esr;
+    int maxevents;
+    unsigned int tun_rwflags;
+#ifdef ENABLE_MANAGEMENT
+    unsigned int management_persist_flags;
+#endif
+};
+
+struct multi_instance;
+struct context;
+
+struct multi_tcp *multi_tcp_init(int maxevents, int *maxclients);
+
+void multi_tcp_free(struct multi_tcp *mtcp);
+
+void multi_tcp_dereference_instance(struct multi_tcp *mtcp, struct multi_instance *mi);
+
+bool multi_tcp_instance_specific_init(struct multi_context *m, struct multi_instance *mi);
+
+void multi_tcp_instance_specific_free(struct multi_instance *mi);
+
+void multi_tcp_link_out_deferred(struct multi_context *m, struct multi_instance *mi);
+
+
+/**************************************************************************/
+/**
+ * Main event loop for OpenVPN in TCP server mode.
+ * @ingroup eventloop
+ *
+ * @param top - Top-level context structure.
+ */
+void tunnel_server_tcp(struct context *top);
+
+
+void multi_tcp_delete_event(struct multi_tcp *mtcp, event_t event);
+
+#endif /* if P2MP_SERVER */
+#endif /* ifndef MTCP_H */
diff --git a/src/openvpn/mtu.c b/src/openvpn/mtu.c
new file mode 100644
index 0000000..04868cd
--- /dev/null
+++ b/src/openvpn/mtu.c
@@ -0,0 +1,346 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "buffer.h"
+#include "error.h"
+#include "integer.h"
+#include "mtu.h"
+#include "options.h"
+
+#include "memdbg.h"
+
+/* allocate a buffer for socket or tun layer */
+void
+alloc_buf_sock_tun(struct buffer *buf,
+                   const struct frame *frame,
+                   const bool tuntap_buffer,
+                   const unsigned int align_mask)
+{
+    /* allocate buffer for overlapped I/O */
+    *buf = alloc_buf(BUF_SIZE(frame));
+    ASSERT(buf_init(buf, FRAME_HEADROOM_ADJ(frame, align_mask)));
+    buf->len = tuntap_buffer ? MAX_RW_SIZE_TUN(frame) : MAX_RW_SIZE_LINK(frame);
+    ASSERT(buf_safe(buf, 0));
+}
+
+void
+frame_finalize(struct frame *frame,
+               bool link_mtu_defined,
+               int link_mtu,
+               bool tun_mtu_defined,
+               int tun_mtu)
+{
+    /* Set link_mtu based on command line options */
+    if (tun_mtu_defined)
+    {
+        ASSERT(!link_mtu_defined);
+        frame->link_mtu = tun_mtu + TUN_LINK_DELTA(frame);
+    }
+    else
+    {
+        ASSERT(link_mtu_defined);
+        frame->link_mtu = link_mtu;
+    }
+
+    if (TUN_MTU_SIZE(frame) < TUN_MTU_MIN)
+    {
+        msg(M_WARN, "TUN MTU value (%d) must be at least %d", TUN_MTU_SIZE(frame), TUN_MTU_MIN);
+        frame_print(frame, M_FATAL, "MTU is too small");
+    }
+
+    frame->link_mtu_dynamic = frame->link_mtu;
+}
+
+/*
+ * Set the tun MTU dynamically.
+ */
+void
+frame_set_mtu_dynamic(struct frame *frame, int mtu, unsigned int flags)
+{
+
+#ifdef ENABLE_DEBUG
+    const int orig_mtu = mtu;
+    const int orig_link_mtu_dynamic = frame->link_mtu_dynamic;
+#endif
+
+    ASSERT(mtu >= 0);
+
+    if (flags & SET_MTU_TUN)
+    {
+        mtu += TUN_LINK_DELTA(frame);
+    }
+
+    if (!(flags & SET_MTU_UPPER_BOUND) || mtu < frame->link_mtu_dynamic)
+    {
+        frame->link_mtu_dynamic = constrain_int(
+            mtu,
+            EXPANDED_SIZE_MIN(frame),
+            EXPANDED_SIZE(frame));
+    }
+
+    dmsg(D_MTU_DEBUG, "MTU DYNAMIC mtu=%d, flags=%u, %d -> %d",
+         orig_mtu,
+         flags,
+         orig_link_mtu_dynamic,
+         frame->link_mtu_dynamic);
+}
+
+/*
+ * Move extra_frame octets into extra_tun.  Used by fragmenting code
+ * to adjust frame relative to its position in the buffer processing
+ * queue.
+ */
+void
+frame_subtract_extra(struct frame *frame, const struct frame *src)
+{
+    frame->extra_frame -= src->extra_frame;
+    frame->extra_tun   += src->extra_frame;
+}
+
+void
+frame_init_mssfix(struct frame *frame, const struct options *options)
+{
+    if (options->ce.mssfix)
+    {
+        frame_set_mtu_dynamic(frame, options->ce.mssfix, SET_MTU_UPPER_BOUND);
+    }
+}
+
+void
+frame_print(const struct frame *frame,
+            int level,
+            const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer out = alloc_buf_gc(256, &gc);
+    if (prefix)
+    {
+        buf_printf(&out, "%s ", prefix);
+    }
+    buf_printf(&out, "[");
+    buf_printf(&out, " L:%d", frame->link_mtu);
+    buf_printf(&out, " D:%d", frame->link_mtu_dynamic);
+    buf_printf(&out, " EF:%d", frame->extra_frame);
+    buf_printf(&out, " EB:%d", frame->extra_buffer);
+    buf_printf(&out, " ET:%d", frame->extra_tun);
+    buf_printf(&out, " EL:%d", frame->extra_link);
+    if (frame->align_flags && frame->align_adjust)
+    {
+        buf_printf(&out, " AF:%u/%d", frame->align_flags, frame->align_adjust);
+    }
+    buf_printf(&out, " ]");
+
+    msg(level, "%s", out.data);
+    gc_free(&gc);
+}
+
+#define MTUDISC_NOT_SUPPORTED_MSG "--mtu-disc is not supported on this OS"
+
+void
+set_mtu_discover_type(int sd, int mtu_type, sa_family_t proto_af)
+{
+    if (mtu_type >= 0)
+    {
+        switch (proto_af)
+        {
+#if defined(HAVE_SETSOCKOPT) && defined(IP_MTU_DISCOVER)
+            case AF_INET:
+                if (setsockopt
+                        (sd, IPPROTO_IP, IP_MTU_DISCOVER, &mtu_type, sizeof(mtu_type)))
+                {
+                    msg(M_ERR, "Error setting IP_MTU_DISCOVER type=%d on TCP/UDP socket",
+                        mtu_type);
+                }
+                break;
+
+#endif
+#if defined(HAVE_SETSOCKOPT) && defined(IPV6_MTU_DISCOVER)
+            case AF_INET6:
+                if (setsockopt
+                        (sd, IPPROTO_IPV6, IPV6_MTU_DISCOVER, &mtu_type, sizeof(mtu_type)))
+                {
+                    msg(M_ERR, "Error setting IPV6_MTU_DISCOVER type=%d on TCP6/UDP6 socket",
+                        mtu_type);
+                }
+                break;
+
+#endif
+            default:
+                msg(M_FATAL, MTUDISC_NOT_SUPPORTED_MSG);
+                break;
+        }
+    }
+}
+
+int
+translate_mtu_discover_type_name(const char *name)
+{
+#if defined(IP_PMTUDISC_DONT) && defined(IP_PMTUDISC_WANT) && defined(IP_PMTUDISC_DO)
+    if (!strcmp(name, "yes"))
+    {
+        return IP_PMTUDISC_DO;
+    }
+    if (!strcmp(name, "maybe"))
+    {
+        return IP_PMTUDISC_WANT;
+    }
+    if (!strcmp(name, "no"))
+    {
+        return IP_PMTUDISC_DONT;
+    }
+    msg(M_FATAL,
+        "invalid --mtu-disc type: '%s' -- valid types are 'yes', 'maybe', or 'no'",
+        name);
+#else  /* if defined(IP_PMTUDISC_DONT) && defined(IP_PMTUDISC_WANT) && defined(IP_PMTUDISC_DO) */
+    msg(M_FATAL, MTUDISC_NOT_SUPPORTED_MSG);
+#endif
+    return -1;                  /* NOTREACHED */
+}
+
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+
+struct probehdr
+{
+    uint32_t ttl;
+    struct timeval tv;
+};
+
+const char *
+format_extended_socket_error(int fd, int *mtu, struct gc_arena *gc)
+{
+    int res;
+    struct probehdr rcvbuf;
+    struct iovec iov;
+    struct msghdr msg;
+    struct cmsghdr *cmsg;
+    struct sock_extended_err *e;
+    struct sockaddr_in addr;
+    struct buffer out = alloc_buf_gc(256, gc);
+    char *cbuf = (char *) gc_malloc(256, false, gc);
+
+    *mtu = 0;
+
+    while (true)
+    {
+        memset(&rcvbuf, -1, sizeof(rcvbuf));
+        iov.iov_base = &rcvbuf;
+        iov.iov_len = sizeof(rcvbuf);
+        msg.msg_name = (uint8_t *) &addr;
+        msg.msg_namelen = sizeof(addr);
+        msg.msg_iov = &iov;
+        msg.msg_iovlen = 1;
+        msg.msg_flags = 0;
+        msg.msg_control = cbuf;
+        msg.msg_controllen = 256; /* size of cbuf */
+
+        res = recvmsg(fd, &msg, MSG_ERRQUEUE);
+        if (res < 0)
+        {
+            goto exit;
+        }
+
+        e = NULL;
+
+        for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg))
+        {
+            if (cmsg->cmsg_level == SOL_IP)
+            {
+                if (cmsg->cmsg_type == IP_RECVERR)
+                {
+                    e = (struct sock_extended_err *) CMSG_DATA(cmsg);
+                }
+                else
+                {
+                    buf_printf(&out,"CMSG=%d|", cmsg->cmsg_type);
+                }
+            }
+        }
+        if (e == NULL)
+        {
+            buf_printf(&out, "NO-INFO|");
+            goto exit;
+        }
+
+        switch (e->ee_errno)
+        {
+            case ETIMEDOUT:
+                buf_printf(&out, "ETIMEDOUT|");
+                break;
+
+            case EMSGSIZE:
+                buf_printf(&out, "EMSGSIZE Path-MTU=%d|", e->ee_info);
+                *mtu = e->ee_info;
+                break;
+
+            case ECONNREFUSED:
+                buf_printf(&out, "ECONNREFUSED|");
+                break;
+
+            case EPROTO:
+                buf_printf(&out, "EPROTO|");
+                break;
+
+            case EHOSTUNREACH:
+                buf_printf(&out, "EHOSTUNREACH|");
+                break;
+
+            case ENETUNREACH:
+                buf_printf(&out, "ENETUNREACH|");
+                break;
+
+            case EACCES:
+                buf_printf(&out, "EACCES|");
+                break;
+
+            default:
+                buf_printf(&out, "UNKNOWN|");
+                break;
+        }
+    }
+
+exit:
+    buf_rmtail(&out, '|');
+    return BSTR(&out);
+}
+
+void
+set_sock_extended_error_passing(int sd)
+{
+    int on = 1;
+    if (setsockopt(sd, SOL_IP, IP_RECVERR, (void *) &on, sizeof(on)))
+    {
+        msg(M_WARN | M_ERRNO,
+            "Note: enable extended error passing on TCP/UDP socket failed (IP_RECVERR)");
+    }
+}
+
+#endif /* if EXTENDED_SOCKET_ERROR_CAPABILITY */
diff --git a/src/openvpn/mtu.h b/src/openvpn/mtu.h
new file mode 100644
index 0000000..cfa8d2f
--- /dev/null
+++ b/src/openvpn/mtu.h
@@ -0,0 +1,327 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MTU_H
+#define MTU_H
+
+#include "buffer.h"
+
+/*
+ *
+ * Packet maninipulation routes such as encrypt, decrypt, compress, decompress
+ * are passed a frame buffer that looks like this:
+ *
+ *    [extra_frame bytes] [mtu bytes] [extra_frame_bytes] [compression overflow bytes]
+ *                         ^
+ *                   Pointer passed to function points here so that routine
+ *                   can make use of extra_frame bytes before pointer
+ *                   to prepend headers, etc.
+ *
+ *    extra_frame bytes is large enough for all encryption related overhead.
+ *
+ *    mtu bytes will be the MTU size set in the ifconfig statement that configures
+ *      the TUN or TAP device such as:
+ *
+ *      ifconfig $1 10.1.0.2 pointopoint 10.1.0.1 mtu 1450
+ *
+ *    Compression overflow bytes is the worst-case size expansion that would be
+ *    expected if we tried to compress mtu + extra_frame bytes of uncompressible data.
+ */
+
+/*
+ * Standard ethernet MTU
+ */
+#define ETHERNET_MTU       1500
+
+/*
+ * It is a fatal error if mtu is less than
+ * this value for tun device.
+ */
+#define TUN_MTU_MIN        100
+
+/*
+ * Default MTU of network over which tunnel data will pass by TCP/UDP.
+ */
+#define LINK_MTU_DEFAULT   1500
+
+/*
+ * Default MTU of tunnel device.
+ */
+#define TUN_MTU_DEFAULT    1500
+
+/*
+ * MTU Defaults for TAP devices
+ */
+#define TAP_MTU_EXTRA_DEFAULT  32
+
+/*
+ * Default MSSFIX value, used for reducing TCP MTU size
+ */
+#define MSSFIX_DEFAULT     1450
+
+/*
+ * Alignment of payload data such as IP packet or
+ * ethernet frame.
+ */
+#define PAYLOAD_ALIGN 4
+
+
+/**************************************************************************/
+/**
+ * Packet geometry parameters.
+ */
+struct frame {
+    int link_mtu;               /**< Maximum packet size to be sent over
+                                 *   the external network interface. */
+
+    int link_mtu_dynamic;       /**< Dynamic MTU value for the external
+                                 *   network interface. */
+
+    int extra_frame;            /**< Maximum number of bytes that all
+                                 *   processing steps together could add.
+                                 *   @code
+                                 *   frame.link_mtu = "socket MTU" - extra_frame;
+                                 *   @endcode
+                                 */
+
+    int extra_buffer;           /**< Maximum number of bytes that
+                                 *   processing steps could expand the
+                                 *   internal work buffer.
+                                 *
+                                 *   This is used by the \link compression
+                                 *   Data Channel Compression
+                                 *   module\endlink to give enough working
+                                 *   space for worst-case expansion of
+                                 *   incompressible content. */
+
+    int extra_tun;              /**< Maximum number of bytes in excess of
+                                 *   the tun/tap MTU that might be read
+                                 *   from or written to the virtual
+                                 *   tun/tap network interface. */
+
+    int extra_link;             /**< Maximum number of bytes in excess of
+                                 *   external network interface's MTU that
+                                 *   might be read from or written to it. */
+
+    /*
+     * Alignment control
+     */
+#define FRAME_HEADROOM_MARKER_DECRYPT     (1<<0)
+#define FRAME_HEADROOM_MARKER_FRAGMENT    (1<<1)
+#define FRAME_HEADROOM_MARKER_READ_LINK   (1<<2)
+#define FRAME_HEADROOM_MARKER_READ_STREAM (1<<3)
+    unsigned int align_flags;
+    int align_adjust;
+};
+
+/* Forward declarations, to prevent includes */
+struct options;
+
+/* Routines which read struct frame should use the macros below */
+
+/*
+ * Overhead added to packet payload due to encapsulation
+ */
+#define EXTRA_FRAME(f)           ((f)->extra_frame)
+
+/*
+ * Delta between tun payload size and final TCP/UDP datagram size
+ * (not including extra_link additions)
+ */
+#define TUN_LINK_DELTA(f)        ((f)->extra_frame + (f)->extra_tun)
+
+/*
+ * This is the size to "ifconfig" the tun or tap device.
+ */
+#define TUN_MTU_SIZE(f)          ((f)->link_mtu - TUN_LINK_DELTA(f))
+#define TUN_MTU_SIZE_DYNAMIC(f)  ((f)->link_mtu_dynamic - TUN_LINK_DELTA(f))
+
+/*
+ * This is the maximum packet size that we need to be able to
+ * read from or write to a tun or tap device.  For example,
+ * a tap device ifconfiged to an MTU of 1200 might actually want
+ * to return a packet size of 1214 on a read().
+ */
+#define PAYLOAD_SIZE(f)          ((f)->link_mtu - (f)->extra_frame)
+#define PAYLOAD_SIZE_DYNAMIC(f)  ((f)->link_mtu_dynamic - (f)->extra_frame)
+
+/*
+ * Max size of a payload packet after encryption, compression, etc.
+ * overhead is added.
+ */
+#define EXPANDED_SIZE(f)         ((f)->link_mtu)
+#define EXPANDED_SIZE_DYNAMIC(f) ((f)->link_mtu_dynamic)
+#define EXPANDED_SIZE_MIN(f)     (TUN_MTU_MIN + TUN_LINK_DELTA(f))
+
+/*
+ * These values are used as maximum size constraints
+ * on read() or write() from TUN/TAP device or TCP/UDP port.
+ */
+#define MAX_RW_SIZE_TUN(f)       (PAYLOAD_SIZE(f))
+#define MAX_RW_SIZE_LINK(f)      (EXPANDED_SIZE(f) + (f)->extra_link)
+
+/*
+ * Control buffer headroom allocations to allow for efficient prepending.
+ */
+#define FRAME_HEADROOM_BASE(f)     (TUN_LINK_DELTA(f) + (f)->extra_buffer + (f)->extra_link)
+#define FRAME_HEADROOM(f)          frame_headroom(f, 0)
+#define FRAME_HEADROOM_ADJ(f, fm)  frame_headroom(f, fm)
+
+/*
+ * Max size of a buffer used to build a packet for output to
+ * the TCP/UDP port.
+ */
+#define BUF_SIZE(f)              (TUN_MTU_SIZE(f) + FRAME_HEADROOM_BASE(f) * 2)
+
+/*
+ * Function prototypes.
+ */
+
+void frame_finalize(struct frame *frame,
+                    bool link_mtu_defined,
+                    int link_mtu,
+                    bool tun_mtu_defined,
+                    int tun_mtu);
+
+void frame_subtract_extra(struct frame *frame, const struct frame *src);
+
+void frame_print(const struct frame *frame,
+                 int level,
+                 const char *prefix);
+
+void set_mtu_discover_type(int sd, int mtu_type, sa_family_t proto_af);
+
+int translate_mtu_discover_type_name(const char *name);
+
+/*
+ * frame_set_mtu_dynamic and flags
+ */
+
+#define SET_MTU_TUN         (1<<0) /* use tun/tap rather than link sizing */
+#define SET_MTU_UPPER_BOUND (1<<1) /* only decrease dynamic MTU */
+
+void frame_set_mtu_dynamic(struct frame *frame, int mtu, unsigned int flags);
+
+/*
+ * allocate a buffer for socket or tun layer
+ */
+void alloc_buf_sock_tun(struct buffer *buf,
+                        const struct frame *frame,
+                        const bool tuntap_buffer,
+                        const unsigned int align_mask);
+
+/** Set the --mssfix option. */
+void frame_init_mssfix(struct frame *frame, const struct options *options);
+
+/*
+ * EXTENDED_SOCKET_ERROR_CAPABILITY functions -- print extra error info
+ * on socket errors, such as PMTU size.  As of 2003.05.11, only works
+ * on Linux 2.4+.
+ */
+
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+
+void set_sock_extended_error_passing(int sd);
+
+const char *format_extended_socket_error(int fd, int *mtu, struct gc_arena *gc);
+
+#endif
+
+/*
+ * Calculate a starting offset into a buffer object, dealing with
+ * headroom and alignment issues.
+ */
+static inline int
+frame_headroom(const struct frame *f, const unsigned int flag_mask)
+{
+    const int offset = FRAME_HEADROOM_BASE(f);
+    const int adjust = (flag_mask & f->align_flags) ? f->align_adjust : 0;
+    const int delta = ((PAYLOAD_ALIGN << 24) - (offset + adjust)) & (PAYLOAD_ALIGN - 1);
+    return offset + delta;
+}
+
+/*
+ * frame member adjustment functions
+ */
+
+static inline void
+frame_add_to_link_mtu(struct frame *frame, const int increment)
+{
+    frame->link_mtu += increment;
+}
+
+static inline void
+frame_add_to_extra_frame(struct frame *frame, const unsigned int increment)
+{
+    frame->extra_frame += increment;
+}
+
+static inline void
+frame_remove_from_extra_frame(struct frame *frame, const unsigned int decrement)
+{
+    frame->extra_frame -= decrement;
+}
+
+static inline void
+frame_add_to_extra_tun(struct frame *frame, const int increment)
+{
+    frame->extra_tun += increment;
+}
+
+static inline void
+frame_add_to_extra_link(struct frame *frame, const int increment)
+{
+    frame->extra_link += increment;
+}
+
+static inline void
+frame_add_to_extra_buffer(struct frame *frame, const int increment)
+{
+    frame->extra_buffer += increment;
+}
+
+static inline void
+frame_add_to_align_adjust(struct frame *frame, const int increment)
+{
+    frame->align_adjust += increment;
+}
+
+static inline void
+frame_align_to_extra_frame(struct frame *frame)
+{
+    frame->align_adjust = frame->extra_frame + frame->extra_link;
+}
+
+static inline void
+frame_or_align_flags(struct frame *frame, const unsigned int flag_mask)
+{
+    frame->align_flags |= flag_mask;
+}
+
+static inline bool
+frame_defined(const struct frame *frame)
+{
+    return frame->link_mtu > 0;
+}
+
+#endif /* ifndef MTU_H */
diff --git a/src/openvpn/mudp.c b/src/openvpn/mudp.c
new file mode 100644
index 0000000..4f63654
--- /dev/null
+++ b/src/openvpn/mudp.c
@@ -0,0 +1,382 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "multi.h"
+#include <inttypes.h>
+#include "forward-inline.h"
+
+#include "memdbg.h"
+
+#ifdef HAVE_SYS_INOTIFY_H
+#include <sys/inotify.h>
+#endif
+
+/*
+ * Get a client instance based on real address.  If
+ * the instance doesn't exist, create it while
+ * maintaining real address hash table atomicity.
+ */
+
+struct multi_instance *
+multi_get_create_instance_udp(struct multi_context *m, bool *floated)
+{
+    struct gc_arena gc = gc_new();
+    struct mroute_addr real;
+    struct multi_instance *mi = NULL;
+    struct hash *hash = m->hash;
+
+    if (mroute_extract_openvpn_sockaddr(&real, &m->top.c2.from.dest, true)
+        && m->top.c2.buf.len > 0)
+    {
+        struct hash_element *he;
+        const uint32_t hv = hash_value(hash, &real);
+        struct hash_bucket *bucket = hash_bucket(hash, hv);
+        uint8_t *ptr = BPTR(&m->top.c2.buf);
+        uint8_t op = ptr[0] >> P_OPCODE_SHIFT;
+        bool v2 = (op == P_DATA_V2) && (m->top.c2.buf.len >= (1 + 3));
+        bool peer_id_disabled = false;
+
+        /* make sure buffer has enough length to read opcode (1 byte) and peer-id (3 bytes) */
+        if (v2)
+        {
+            uint32_t peer_id = ntohl(*(uint32_t *)ptr) & 0xFFFFFF;
+            peer_id_disabled = (peer_id == MAX_PEER_ID);
+
+            if (!peer_id_disabled && (peer_id < m->max_clients) && (m->instances[peer_id]))
+            {
+                mi = m->instances[peer_id];
+
+                *floated = !link_socket_actual_match(&mi->context.c2.from, &m->top.c2.from);
+
+                if (*floated)
+                {
+                    /* reset prefix, since here we are not sure peer is the one it claims to be */
+                    ungenerate_prefix(mi);
+                    msg(D_MULTI_MEDIUM, "Float requested for peer %" PRIu32 " to %s", peer_id,
+                        mroute_addr_print(&real, &gc));
+                }
+            }
+        }
+        if (!v2 || peer_id_disabled)
+        {
+            he = hash_lookup_fast(hash, bucket, &real, hv);
+            if (he)
+            {
+                mi = (struct multi_instance *) he->value;
+            }
+        }
+        if (!mi)
+        {
+            if (!m->top.c2.tls_auth_standalone
+                || tls_pre_decrypt_lite(m->top.c2.tls_auth_standalone, &m->top.c2.from, &m->top.c2.buf))
+            {
+                if (frequency_limit_event_allowed(m->new_connection_limiter))
+                {
+                    mi = multi_create_instance(m, &real);
+                    if (mi)
+                    {
+                        int i;
+
+                        hash_add_fast(hash, bucket, &mi->real, hv, mi);
+                        mi->did_real_hash = true;
+
+                        /* max_clients must be less then max peer-id value */
+                        ASSERT(m->max_clients < MAX_PEER_ID);
+
+                        for (i = 0; i < m->max_clients; ++i)
+                        {
+                            if (!m->instances[i])
+                            {
+                                mi->context.c2.tls_multi->peer_id = i;
+                                m->instances[i] = mi;
+                                break;
+                            }
+                        }
+
+                        /* should not really end up here, since multi_create_instance returns null
+                         * if amount of clients exceeds max_clients */
+                        ASSERT(i < m->max_clients);
+                    }
+                }
+                else
+                {
+                    msg(D_MULTI_ERRORS,
+                        "MULTI: Connection from %s would exceed new connection frequency limit as controlled by --connect-freq",
+                        mroute_addr_print(&real, &gc));
+                }
+            }
+        }
+
+#ifdef ENABLE_DEBUG
+        if (check_debug_level(D_MULTI_DEBUG))
+        {
+            const char *status = mi ? "[ok]" : "[failed]";
+
+            dmsg(D_MULTI_DEBUG, "GET INST BY REAL: %s %s",
+                 mroute_addr_print(&real, &gc),
+                 status);
+        }
+#endif
+    }
+
+    gc_free(&gc);
+    ASSERT(!(mi && mi->halt));
+    return mi;
+}
+
+/*
+ * Send a packet to TCP/UDP socket.
+ */
+static inline void
+multi_process_outgoing_link(struct multi_context *m, const unsigned int mpp_flags)
+{
+    struct multi_instance *mi = multi_process_outgoing_link_pre(m);
+    if (mi)
+    {
+        multi_process_outgoing_link_dowork(m, mi, mpp_flags);
+    }
+}
+
+/*
+ * Process an I/O event.
+ */
+static void
+multi_process_io_udp(struct multi_context *m)
+{
+    const unsigned int status = m->top.c2.event_set_status;
+    const unsigned int mpp_flags = m->top.c2.fast_io
+                                   ? (MPP_CONDITIONAL_PRE_SELECT | MPP_CLOSE_ON_SIGNAL)
+                                   : (MPP_PRE_SELECT | MPP_CLOSE_ON_SIGNAL);
+
+#ifdef MULTI_DEBUG_EVENT_LOOP
+    char buf[16];
+    buf[0] = 0;
+    if (status & SOCKET_READ)
+    {
+        strcat(buf, "SR/");
+    }
+    else if (status & SOCKET_WRITE)
+    {
+        strcat(buf, "SW/");
+    }
+    else if (status & TUN_READ)
+    {
+        strcat(buf, "TR/");
+    }
+    else if (status & TUN_WRITE)
+    {
+        strcat(buf, "TW/");
+    }
+#ifdef ENABLE_ASYNC_PUSH
+    else if (status & FILE_CLOSED)
+    {
+        strcat(buf, "FC/");
+    }
+#endif
+    printf("IO %s\n", buf);
+#endif /* ifdef MULTI_DEBUG_EVENT_LOOP */
+
+#ifdef ENABLE_MANAGEMENT
+    if (status & (MANAGEMENT_READ|MANAGEMENT_WRITE))
+    {
+        ASSERT(management);
+        management_io(management);
+    }
+#endif
+
+    /* UDP port ready to accept write */
+    if (status & SOCKET_WRITE)
+    {
+        multi_process_outgoing_link(m, mpp_flags);
+    }
+    /* TUN device ready to accept write */
+    else if (status & TUN_WRITE)
+    {
+        multi_process_outgoing_tun(m, mpp_flags);
+    }
+    /* Incoming data on UDP port */
+    else if (status & SOCKET_READ)
+    {
+        read_incoming_link(&m->top);
+        if (!IS_SIG(&m->top))
+        {
+            multi_process_incoming_link(m, NULL, mpp_flags);
+        }
+    }
+    /* Incoming data on TUN device */
+    else if (status & TUN_READ)
+    {
+        read_incoming_tun(&m->top);
+        if (!IS_SIG(&m->top))
+        {
+            multi_process_incoming_tun(m, mpp_flags);
+        }
+    }
+#ifdef ENABLE_ASYNC_PUSH
+    /* INOTIFY callback */
+    else if (status & FILE_CLOSED)
+    {
+        multi_process_file_closed(m, mpp_flags);
+    }
+#endif
+}
+
+/*
+ * Return the io_wait() flags appropriate for
+ * a point-to-multipoint tunnel.
+ */
+static inline unsigned int
+p2mp_iow_flags(const struct multi_context *m)
+{
+    unsigned int flags = IOW_WAIT_SIGNAL;
+    if (m->pending)
+    {
+        if (TUN_OUT(&m->pending->context))
+        {
+            flags |= IOW_TO_TUN;
+        }
+        if (LINK_OUT(&m->pending->context))
+        {
+            flags |= IOW_TO_LINK;
+        }
+    }
+    else if (mbuf_defined(m->mbuf))
+    {
+        flags |= IOW_MBUF;
+    }
+    else
+    {
+        flags |= IOW_READ;
+    }
+
+    return flags;
+}
+
+
+/**************************************************************************/
+/**
+ * Main event loop for OpenVPN in UDP server mode.
+ * @ingroup eventloop
+ *
+ * This function implements OpenVPN's main event loop for UDP server mode.
+ *  At this time, OpenVPN does not yet support multithreading.  This
+ * function's name is therefore slightly misleading.
+ *
+ * @param top - Top-level context structure.
+ */
+static void
+tunnel_server_udp_single_threaded(struct context *top)
+{
+    struct multi_context multi;
+
+    top->mode = CM_TOP;
+    context_clear_2(top);
+
+    /* initialize top-tunnel instance */
+    init_instance_handle_signals(top, top->es, CC_HARD_USR1_TO_HUP);
+    if (IS_SIG(top))
+    {
+        return;
+    }
+
+    /* initialize global multi_context object */
+    multi_init(&multi, top, false, MC_SINGLE_THREADED);
+
+    /* initialize our cloned top object */
+    multi_top_init(&multi, top);
+
+    /* initialize management interface */
+    init_management_callback_multi(&multi);
+
+    /* finished with initialization */
+    initialization_sequence_completed(top, ISC_SERVER); /* --mode server --proto udp */
+
+#ifdef ENABLE_ASYNC_PUSH
+    multi.top.c2.inotify_fd = inotify_init();
+    if (multi.top.c2.inotify_fd < 0)
+    {
+        msg(D_MULTI_ERRORS | M_ERRNO, "MULTI: inotify_init error");
+    }
+#endif
+
+    /* per-packet event loop */
+    while (true)
+    {
+        perf_push(PERF_EVENT_LOOP);
+
+        /* set up and do the io_wait() */
+        multi_get_timeout(&multi, &multi.top.c2.timeval);
+        io_wait(&multi.top, p2mp_iow_flags(&multi));
+        MULTI_CHECK_SIG(&multi);
+
+        /* check on status of coarse timers */
+        multi_process_per_second_timers(&multi);
+
+        /* timeout? */
+        if (multi.top.c2.event_set_status == ES_TIMEOUT)
+        {
+            multi_process_timeout(&multi, MPP_PRE_SELECT|MPP_CLOSE_ON_SIGNAL);
+        }
+        else
+        {
+            /* process I/O */
+            multi_process_io_udp(&multi);
+            MULTI_CHECK_SIG(&multi);
+        }
+
+        perf_pop();
+    }
+
+#ifdef ENABLE_ASYNC_PUSH
+    close(top->c2.inotify_fd);
+#endif
+
+    /* shut down management interface */
+    uninit_management_callback();
+
+    /* save ifconfig-pool */
+    multi_ifconfig_pool_persist(&multi, true);
+
+    /* tear down tunnel instance (unless --persist-tun) */
+    multi_uninit(&multi);
+    multi_top_free(&multi);
+    close_instance(top);
+}
+
+void
+tunnel_server_udp(struct context *top)
+{
+    tunnel_server_udp_single_threaded(top);
+}
+
+#endif /* if P2MP_SERVER */
diff --git a/src/openvpn/mudp.h b/src/openvpn/mudp.h
new file mode 100644
index 0000000..7e31151
--- /dev/null
+++ b/src/openvpn/mudp.h
@@ -0,0 +1,70 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * UDP specific code for --mode server
+ */
+
+#ifndef MUDP_H
+#define MUDP_H
+
+#if P2MP_SERVER
+
+struct context;
+struct multi_context;
+
+
+/**************************************************************************/
+/**
+ * Main event loop wrapper function for OpenVPN in UDP server mode.
+ * @ingroup eventloop
+ *
+ * This function simply calls \c tunnel_server_udp_single_threaded().
+ *
+ * @param top          - Top-level context structure.
+ */
+void tunnel_server_udp(struct context *top);
+
+
+/**************************************************************************/
+/**
+ * Get, and if necessary create, the multi_instance associated with a
+ * packet's source address.
+ * @ingroup external_multiplexer
+ *
+ * This function extracts the source address of a recently read packet
+ * from \c m->top.c2.from and uses that source address as a hash key for
+ * the hash table \c m->hash.  If an entry exists, this function returns
+ * it.  If no entry exists, this function handles its creation, and if
+ * successful, returns the newly created instance.
+ *
+ * @param m            - The single multi_context structure.
+ *
+ * @return A pointer to a multi_instance if one already existed for the
+ *     packet's source address or if one was a newly created successfully.
+ *      NULL if one did not yet exist and a new one was not created.
+ */
+struct multi_instance *multi_get_create_instance_udp(struct multi_context *m, bool *floated);
+
+#endif
+#endif
diff --git a/src/openvpn/multi.c b/src/openvpn/multi.c
new file mode 100644
index 0000000..c8c9a40
--- /dev/null
+++ b/src/openvpn/multi.c
@@ -0,0 +1,3402 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#ifdef HAVE_SYS_INOTIFY_H
+#include <sys/inotify.h>
+#define INOTIFY_EVENT_BUFFER_SIZE 16384
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "multi.h"
+#include "push.h"
+#include "misc.h"
+#include "otime.h"
+#include "gremlin.h"
+#include "mstats.h"
+#include "ssl_verify.h"
+#include <inttypes.h>
+
+#include "memdbg.h"
+
+#include "forward-inline.h"
+#include "pf-inline.h"
+
+/*#define MULTI_DEBUG_EVENT_LOOP*/
+
+#ifdef MULTI_DEBUG_EVENT_LOOP
+static const char *
+id(struct multi_instance *mi)
+{
+    if (mi)
+    {
+        return tls_common_name(mi->context.c2.tls_multi, false);
+    }
+    else
+    {
+        return "NULL";
+    }
+}
+#endif
+
+#ifdef MANAGEMENT_DEF_AUTH
+static void
+set_cc_config(struct multi_instance *mi, struct buffer_list *cc_config)
+{
+    if (mi->cc_config)
+    {
+        buffer_list_free(mi->cc_config);
+    }
+    mi->cc_config = cc_config;
+}
+#endif
+
+static inline void
+update_mstat_n_clients(const int n_clients)
+{
+#ifdef ENABLE_MEMSTATS
+    if (mmap_stats)
+    {
+        mmap_stats->n_clients = n_clients;
+    }
+#endif
+}
+
+static bool
+learn_address_script(const struct multi_context *m,
+                     const struct multi_instance *mi,
+                     const char *op,
+                     const struct mroute_addr *addr)
+{
+    struct gc_arena gc = gc_new();
+    struct env_set *es;
+    bool ret = true;
+    struct plugin_list *plugins;
+
+    /* get environmental variable source */
+    if (mi && mi->context.c2.es)
+    {
+        es = mi->context.c2.es;
+    }
+    else
+    {
+        es = env_set_create(&gc);
+    }
+
+    /* get plugin source */
+    if (mi)
+    {
+        plugins = mi->context.plugins;
+    }
+    else
+    {
+        plugins = m->top.plugins;
+    }
+
+    if (plugin_defined(plugins, OPENVPN_PLUGIN_LEARN_ADDRESS))
+    {
+        struct argv argv = argv_new();
+        argv_printf(&argv, "%s %s",
+                    op,
+                    mroute_addr_print(addr, &gc));
+        if (mi)
+        {
+            argv_printf_cat(&argv, "%s", tls_common_name(mi->context.c2.tls_multi, false));
+        }
+        if (plugin_call(plugins, OPENVPN_PLUGIN_LEARN_ADDRESS, &argv, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            msg(M_WARN, "WARNING: learn-address plugin call failed");
+            ret = false;
+        }
+        argv_reset(&argv);
+    }
+
+    if (m->top.options.learn_address_script)
+    {
+        struct argv argv = argv_new();
+        setenv_str(es, "script_type", "learn-address");
+        argv_parse_cmd(&argv, m->top.options.learn_address_script);
+        argv_printf_cat(&argv, "%s %s", op, mroute_addr_print(addr, &gc));
+        if (mi)
+        {
+            argv_printf_cat(&argv, "%s", tls_common_name(mi->context.c2.tls_multi, false));
+        }
+        if (!openvpn_run_script(&argv, es, 0, "--learn-address"))
+        {
+            ret = false;
+        }
+        argv_reset(&argv);
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+void
+multi_ifconfig_pool_persist(struct multi_context *m, bool force)
+{
+    /* write pool data to file */
+    if (m->ifconfig_pool
+        && m->top.c1.ifconfig_pool_persist
+        && (force || ifconfig_pool_write_trigger(m->top.c1.ifconfig_pool_persist)))
+    {
+        ifconfig_pool_write(m->top.c1.ifconfig_pool_persist, m->ifconfig_pool);
+    }
+}
+
+static void
+multi_reap_range(const struct multi_context *m,
+                 int start_bucket,
+                 int end_bucket)
+{
+    struct gc_arena gc = gc_new();
+    struct hash_iterator hi;
+    struct hash_element *he;
+
+    if (start_bucket < 0)
+    {
+        start_bucket = 0;
+        end_bucket = hash_n_buckets(m->vhash);
+    }
+
+    dmsg(D_MULTI_DEBUG, "MULTI: REAP range %d -> %d", start_bucket, end_bucket);
+    hash_iterator_init_range(m->vhash, &hi, start_bucket, end_bucket);
+    while ((he = hash_iterator_next(&hi)) != NULL)
+    {
+        struct multi_route *r = (struct multi_route *) he->value;
+        if (!multi_route_defined(m, r))
+        {
+            dmsg(D_MULTI_DEBUG, "MULTI: REAP DEL %s",
+                 mroute_addr_print(&r->addr, &gc));
+            learn_address_script(m, NULL, "delete", &r->addr);
+            multi_route_del(r);
+            hash_iterator_delete_element(&hi);
+        }
+    }
+    hash_iterator_free(&hi);
+    gc_free(&gc);
+}
+
+static void
+multi_reap_all(const struct multi_context *m)
+{
+    multi_reap_range(m, -1, 0);
+}
+
+static struct multi_reap *
+multi_reap_new(int buckets_per_pass)
+{
+    struct multi_reap *mr;
+    ALLOC_OBJ(mr, struct multi_reap);
+    mr->bucket_base = 0;
+    mr->buckets_per_pass = buckets_per_pass;
+    mr->last_call = now;
+    return mr;
+}
+
+void
+multi_reap_process_dowork(const struct multi_context *m)
+{
+    struct multi_reap *mr = m->reaper;
+    if (mr->bucket_base >= hash_n_buckets(m->vhash))
+    {
+        mr->bucket_base = 0;
+    }
+    multi_reap_range(m, mr->bucket_base, mr->bucket_base + mr->buckets_per_pass);
+    mr->bucket_base += mr->buckets_per_pass;
+    mr->last_call = now;
+}
+
+static void
+multi_reap_free(struct multi_reap *mr)
+{
+    free(mr);
+}
+
+/*
+ * How many buckets in vhash to reap per pass.
+ */
+static int
+reap_buckets_per_pass(int n_buckets)
+{
+    return constrain_int(n_buckets / REAP_DIVISOR, REAP_MIN, REAP_MAX);
+}
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+static uint32_t
+cid_hash_function(const void *key, uint32_t iv)
+{
+    const unsigned long *k = (const unsigned long *)key;
+    return (uint32_t) *k;
+}
+
+static bool
+cid_compare_function(const void *key1, const void *key2)
+{
+    const unsigned long *k1 = (const unsigned long *)key1;
+    const unsigned long *k2 = (const unsigned long *)key2;
+    return *k1 == *k2;
+}
+
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+static uint32_t
+/*
+ * inotify watcher descriptors are used as hash value
+ */
+int_hash_function(const void *key, uint32_t iv)
+{
+    return (unsigned long)key;
+}
+
+static bool
+int_compare_function(const void *key1, const void *key2)
+{
+    return (unsigned long)key1 == (unsigned long)key2;
+}
+#endif
+
+/*
+ * Main initialization function, init multi_context object.
+ */
+void
+multi_init(struct multi_context *m, struct context *t, bool tcp_mode, int thread_mode)
+{
+    int dev = DEV_TYPE_UNDEF;
+
+    msg(D_MULTI_LOW, "MULTI: multi_init called, r=%d v=%d",
+        t->options.real_hash_size,
+        t->options.virtual_hash_size);
+
+    /*
+     * Get tun/tap/null device type
+     */
+    dev = dev_type_enum(t->options.dev, t->options.dev_type);
+
+    /*
+     * Init our multi_context object.
+     */
+    CLEAR(*m);
+
+    m->thread_mode = thread_mode;
+
+    /*
+     * Real address hash table (source port number is
+     * considered to be part of the address).  Used
+     * to determine which client sent an incoming packet
+     * which is seen on the TCP/UDP socket.
+     */
+    m->hash = hash_init(t->options.real_hash_size,
+                        get_random(),
+                        mroute_addr_hash_function,
+                        mroute_addr_compare_function);
+
+    /*
+     * Virtual address hash table.  Used to determine
+     * which client to route a packet to.
+     */
+    m->vhash = hash_init(t->options.virtual_hash_size,
+                         get_random(),
+                         mroute_addr_hash_function,
+                         mroute_addr_compare_function);
+
+    /*
+     * This hash table is a clone of m->hash but with a
+     * bucket size of one so that it can be used
+     * for fast iteration through the list.
+     */
+    m->iter = hash_init(1,
+                        get_random(),
+                        mroute_addr_hash_function,
+                        mroute_addr_compare_function);
+
+#ifdef MANAGEMENT_DEF_AUTH
+    m->cid_hash = hash_init(t->options.real_hash_size,
+                            0,
+                            cid_hash_function,
+                            cid_compare_function);
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+    /*
+     * Mapping between inotify watch descriptors and
+     * multi_instances.
+     */
+    m->inotify_watchers = hash_init(t->options.real_hash_size,
+                                    get_random(),
+                                    int_hash_function,
+                                    int_compare_function);
+#endif
+
+    /*
+     * This is our scheduler, for time-based wakeup
+     * events.
+     */
+    m->schedule = schedule_init();
+
+    /*
+     * Limit frequency of incoming connections to control
+     * DoS.
+     */
+    m->new_connection_limiter = frequency_limit_init(t->options.cf_max,
+                                                     t->options.cf_per);
+
+    /*
+     * Allocate broadcast/multicast buffer list
+     */
+    m->mbuf = mbuf_init(t->options.n_bcast_buf);
+
+    /*
+     * Different status file format options are available
+     */
+    m->status_file_version = t->options.status_file_version;
+
+    /*
+     * Possibly allocate an ifconfig pool, do it
+     * differently based on whether a tun or tap style
+     * tunnel.
+     */
+    if (t->options.ifconfig_pool_defined)
+    {
+        int pool_type = IFCONFIG_POOL_INDIV;
+
+        if (dev == DEV_TYPE_TUN && t->options.topology == TOP_NET30)
+        {
+            pool_type = IFCONFIG_POOL_30NET;
+        }
+
+        m->ifconfig_pool = ifconfig_pool_init(pool_type,
+                                              t->options.ifconfig_pool_start,
+                                              t->options.ifconfig_pool_end,
+                                              t->options.duplicate_cn,
+                                              t->options.ifconfig_ipv6_pool_defined,
+                                              t->options.ifconfig_ipv6_pool_base,
+                                              t->options.ifconfig_ipv6_pool_netbits );
+
+        /* reload pool data from file */
+        if (t->c1.ifconfig_pool_persist)
+        {
+            ifconfig_pool_read(t->c1.ifconfig_pool_persist, m->ifconfig_pool);
+        }
+    }
+
+    /*
+     * Help us keep track of routing table.
+     */
+    m->route_helper = mroute_helper_init(MULTI_CACHE_ROUTE_TTL);
+
+    /*
+     * Initialize route and instance reaper.
+     */
+    m->reaper = multi_reap_new(reap_buckets_per_pass(t->options.virtual_hash_size));
+
+    /*
+     * Get local ifconfig address
+     */
+    CLEAR(m->local);
+    ASSERT(t->c1.tuntap);
+    mroute_extract_in_addr_t(&m->local, t->c1.tuntap->local);
+
+    /*
+     * Per-client limits
+     */
+    m->max_clients = t->options.max_clients;
+
+    m->instances = calloc(m->max_clients, sizeof(struct multi_instance *));
+
+    /*
+     * Initialize multi-socket TCP I/O wait object
+     */
+    if (tcp_mode)
+    {
+        m->mtcp = multi_tcp_init(t->options.max_clients, &m->max_clients);
+    }
+    m->tcp_queue_limit = t->options.tcp_queue_limit;
+
+    /*
+     * Allow client <-> client communication, without going through
+     * tun/tap interface and network stack?
+     */
+    m->enable_c2c = t->options.enable_c2c;
+
+    /* initialize stale routes check timer */
+    if (t->options.stale_routes_check_interval > 0)
+    {
+        msg(M_INFO, "Initializing stale route check timer to run every %i seconds and to removing routes with activity timeout older than %i seconds",
+            t->options.stale_routes_check_interval, t->options.stale_routes_ageing_time);
+        event_timeout_init(&m->stale_routes_check_et, t->options.stale_routes_check_interval, 0);
+    }
+
+    m->deferred_shutdown_signal.signal_received = 0;
+}
+
+const char *
+multi_instance_string(const struct multi_instance *mi, bool null, struct gc_arena *gc)
+{
+    if (mi)
+    {
+        struct buffer out = alloc_buf_gc(MULTI_PREFIX_MAX_LENGTH, gc);
+        const char *cn = tls_common_name(mi->context.c2.tls_multi, true);
+
+        if (cn)
+        {
+            buf_printf(&out, "%s/", cn);
+        }
+        buf_printf(&out, "%s", mroute_addr_print(&mi->real, gc));
+        return BSTR(&out);
+    }
+    else if (null)
+    {
+        return NULL;
+    }
+    else
+    {
+        return "UNDEF";
+    }
+}
+
+static void
+generate_prefix(struct multi_instance *mi)
+{
+    struct gc_arena gc = gc_new();
+    const char *prefix = multi_instance_string(mi, true, &gc);
+    if (prefix)
+    {
+        strncpynt(mi->msg_prefix, prefix, sizeof(mi->msg_prefix));
+    }
+    else
+    {
+        mi->msg_prefix[0] = '\0';
+    }
+    set_prefix(mi);
+    gc_free(&gc);
+}
+
+void
+ungenerate_prefix(struct multi_instance *mi)
+{
+    mi->msg_prefix[0] = '\0';
+    set_prefix(mi);
+}
+
+static const char *
+mi_prefix(const struct multi_instance *mi)
+{
+    if (mi && mi->msg_prefix[0])
+    {
+        return mi->msg_prefix;
+    }
+    else
+    {
+        return "UNDEF_I";
+    }
+}
+
+/*
+ * Tell the route helper about deleted iroutes so
+ * that it can update its mask of currently used
+ * CIDR netlengths.
+ */
+static void
+multi_del_iroutes(struct multi_context *m,
+                  struct multi_instance *mi)
+{
+    const struct iroute *ir;
+    const struct iroute_ipv6 *ir6;
+    if (TUNNEL_TYPE(mi->context.c1.tuntap) == DEV_TYPE_TUN)
+    {
+        for (ir = mi->context.options.iroutes; ir != NULL; ir = ir->next)
+        {
+            mroute_helper_del_iroute46(m->route_helper, ir->netbits);
+        }
+
+        for (ir6 = mi->context.options.iroutes_ipv6; ir6 != NULL; ir6 = ir6->next)
+        {
+            mroute_helper_del_iroute46(m->route_helper, ir6->netbits);
+        }
+    }
+}
+
+static void
+setenv_stats(struct context *c)
+{
+    setenv_counter(c->c2.es, "bytes_received", c->c2.link_read_bytes);
+    setenv_counter(c->c2.es, "bytes_sent", c->c2.link_write_bytes);
+}
+
+static void
+multi_client_disconnect_setenv(struct multi_instance *mi)
+{
+    /* setenv client real IP address */
+    setenv_trusted(mi->context.c2.es, get_link_socket_info(&mi->context));
+
+    /* setenv stats */
+    setenv_stats(&mi->context);
+
+    /* setenv connection duration */
+    {
+        const unsigned int duration = (unsigned int) now - mi->created;
+        setenv_unsigned(mi->context.c2.es, "time_duration", duration);
+    }
+}
+
+static void
+multi_client_disconnect_script(struct multi_instance *mi)
+{
+    if ((mi->context.c2.context_auth == CAS_SUCCEEDED && mi->connection_established_flag)
+        || mi->context.c2.context_auth == CAS_PARTIAL)
+    {
+        multi_client_disconnect_setenv(mi);
+
+        if (plugin_defined(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_DISCONNECT))
+        {
+            if (plugin_call(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_DISCONNECT, NULL, NULL, mi->context.c2.es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+            {
+                msg(M_WARN, "WARNING: client-disconnect plugin call failed");
+            }
+        }
+
+        if (mi->context.options.client_disconnect_script)
+        {
+            struct argv argv = argv_new();
+            setenv_str(mi->context.c2.es, "script_type", "client-disconnect");
+            argv_parse_cmd(&argv, mi->context.options.client_disconnect_script);
+            openvpn_run_script(&argv, mi->context.c2.es, 0, "--client-disconnect");
+            argv_reset(&argv);
+        }
+#ifdef MANAGEMENT_DEF_AUTH
+        if (management)
+        {
+            management_notify_client_close(management, &mi->context.c2.mda_context, mi->context.c2.es);
+        }
+#endif
+
+    }
+}
+
+void
+multi_close_instance(struct multi_context *m,
+                     struct multi_instance *mi,
+                     bool shutdown)
+{
+    perf_push(PERF_MULTI_CLOSE_INSTANCE);
+
+    ASSERT(!mi->halt);
+    mi->halt = true;
+
+    dmsg(D_MULTI_DEBUG, "MULTI: multi_close_instance called");
+
+    /* adjust current client connection count */
+    m->n_clients += mi->n_clients_delta;
+    update_mstat_n_clients(m->n_clients);
+    mi->n_clients_delta = 0;
+
+    /* prevent dangling pointers */
+    if (m->pending == mi)
+    {
+        multi_set_pending(m, NULL);
+    }
+    if (m->earliest_wakeup == mi)
+    {
+        m->earliest_wakeup = NULL;
+    }
+
+    if (!shutdown)
+    {
+        if (mi->did_real_hash)
+        {
+            ASSERT(hash_remove(m->hash, &mi->real));
+        }
+        if (mi->did_iter)
+        {
+            ASSERT(hash_remove(m->iter, &mi->real));
+        }
+#ifdef MANAGEMENT_DEF_AUTH
+        if (mi->did_cid_hash)
+        {
+            ASSERT(hash_remove(m->cid_hash, &mi->context.c2.mda_context.cid));
+        }
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+        if (mi->inotify_watch != -1)
+        {
+            hash_remove(m->inotify_watchers, (void *) (unsigned long)mi->inotify_watch);
+            mi->inotify_watch = -1;
+        }
+#endif
+
+        if (mi->context.c2.tls_multi->peer_id != MAX_PEER_ID)
+        {
+            m->instances[mi->context.c2.tls_multi->peer_id] = NULL;
+        }
+
+        schedule_remove_entry(m->schedule, (struct schedule_entry *) mi);
+
+        ifconfig_pool_release(m->ifconfig_pool, mi->vaddr_handle, false);
+
+        if (mi->did_iroutes)
+        {
+            multi_del_iroutes(m, mi);
+            mi->did_iroutes = false;
+        }
+
+        if (m->mtcp)
+        {
+            multi_tcp_dereference_instance(m->mtcp, mi);
+        }
+
+        mbuf_dereference_instance(m->mbuf, mi);
+    }
+
+#ifdef MANAGEMENT_DEF_AUTH
+    set_cc_config(mi, NULL);
+#endif
+
+    multi_client_disconnect_script(mi);
+
+    if (mi->did_open_context)
+    {
+        close_context(&mi->context, SIGTERM, CC_GC_FREE);
+    }
+
+    multi_tcp_instance_specific_free(mi);
+
+    ungenerate_prefix(mi);
+
+    /*
+     * Don't actually delete the instance memory allocation yet,
+     * because virtual routes may still point to it.  Let the
+     * vhash reaper deal with it.
+     */
+    multi_instance_dec_refcount(mi);
+
+    perf_pop();
+}
+
+/*
+ * Called on shutdown or restart.
+ */
+void
+multi_uninit(struct multi_context *m)
+{
+    if (m->thread_mode & MC_WORK_THREAD)
+    {
+        multi_top_free(m);
+        m->thread_mode = MC_UNDEF;
+    }
+    else if (m->thread_mode)
+    {
+        if (m->hash)
+        {
+            struct hash_iterator hi;
+            struct hash_element *he;
+
+            hash_iterator_init(m->iter, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct multi_instance *mi = (struct multi_instance *) he->value;
+                mi->did_iter = false;
+                multi_close_instance(m, mi, true);
+            }
+            hash_iterator_free(&hi);
+
+            multi_reap_all(m);
+
+            hash_free(m->hash);
+            hash_free(m->vhash);
+            hash_free(m->iter);
+#ifdef MANAGEMENT_DEF_AUTH
+            hash_free(m->cid_hash);
+#endif
+            m->hash = NULL;
+
+            free(m->instances);
+
+#ifdef ENABLE_ASYNC_PUSH
+            hash_free(m->inotify_watchers);
+            m->inotify_watchers = NULL;
+#endif
+
+            schedule_free(m->schedule);
+            mbuf_free(m->mbuf);
+            ifconfig_pool_free(m->ifconfig_pool);
+            frequency_limit_free(m->new_connection_limiter);
+            multi_reap_free(m->reaper);
+            mroute_helper_free(m->route_helper);
+            multi_tcp_free(m->mtcp);
+            m->thread_mode = MC_UNDEF;
+        }
+    }
+}
+
+/*
+ * Create a client instance object for a newly connected client.
+ */
+struct multi_instance *
+multi_create_instance(struct multi_context *m, const struct mroute_addr *real)
+{
+    struct gc_arena gc = gc_new();
+    struct multi_instance *mi;
+
+    perf_push(PERF_MULTI_CREATE_INSTANCE);
+
+    msg(D_MULTI_MEDIUM, "MULTI: multi_create_instance called");
+
+    ALLOC_OBJ_CLEAR(mi, struct multi_instance);
+
+    mi->gc = gc_new();
+    multi_instance_inc_refcount(mi);
+    mi->vaddr_handle = -1;
+    mi->created = now;
+    mroute_addr_init(&mi->real);
+
+    if (real)
+    {
+        mi->real = *real;
+        generate_prefix(mi);
+    }
+
+    mi->did_open_context = true;
+    inherit_context_child(&mi->context, &m->top);
+    if (IS_SIG(&mi->context))
+    {
+        goto err;
+    }
+
+    mi->context.c2.context_auth = CAS_PENDING;
+
+    if (hash_n_elements(m->hash) >= m->max_clients)
+    {
+        msg(D_MULTI_ERRORS, "MULTI: new incoming connection would exceed maximum number of clients (%d)", m->max_clients);
+        goto err;
+    }
+
+    if (!real) /* TCP mode? */
+    {
+        if (!multi_tcp_instance_specific_init(m, mi))
+        {
+            goto err;
+        }
+        generate_prefix(mi);
+    }
+
+    if (!hash_add(m->iter, &mi->real, mi, false))
+    {
+        msg(D_MULTI_LOW, "MULTI: unable to add real address [%s] to iterator hash table",
+            mroute_addr_print(&mi->real, &gc));
+        goto err;
+    }
+    mi->did_iter = true;
+
+#ifdef MANAGEMENT_DEF_AUTH
+    do
+    {
+        mi->context.c2.mda_context.cid = m->cid_counter++;
+    } while (!hash_add(m->cid_hash, &mi->context.c2.mda_context.cid, mi, false));
+    mi->did_cid_hash = true;
+#endif
+
+    mi->context.c2.push_reply_deferred = true;
+
+#ifdef ENABLE_ASYNC_PUSH
+    mi->context.c2.push_request_received = false;
+    mi->inotify_watch = -1;
+#endif
+
+    if (!multi_process_post(m, mi, MPP_PRE_SELECT))
+    {
+        msg(D_MULTI_ERRORS, "MULTI: signal occurred during client instance initialization");
+        goto err;
+    }
+
+    perf_pop();
+    gc_free(&gc);
+    return mi;
+
+err:
+    multi_close_instance(m, mi, false);
+    perf_pop();
+    gc_free(&gc);
+    return NULL;
+}
+
+/*
+ * Dump tables -- triggered by SIGUSR2.
+ * If status file is defined, write to file.
+ * If status file is NULL, write to syslog.
+ */
+void
+multi_print_status(struct multi_context *m, struct status_output *so, const int version)
+{
+    if (m->hash)
+    {
+        struct gc_arena gc_top = gc_new();
+        struct hash_iterator hi;
+        const struct hash_element *he;
+
+        status_reset(so);
+
+        if (version == 1) /* WAS: m->status_file_version */
+        {
+            /*
+             * Status file version 1
+             */
+            status_printf(so, "OpenVPN CLIENT LIST");
+            status_printf(so, "Updated,%s", time_string(0, 0, false, &gc_top));
+            status_printf(so, "Common Name,Real Address,Bytes Received,Bytes Sent,Connected Since");
+            hash_iterator_init(m->hash, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct gc_arena gc = gc_new();
+                const struct multi_instance *mi = (struct multi_instance *) he->value;
+
+                if (!mi->halt)
+                {
+                    status_printf(so, "%s,%s," counter_format "," counter_format ",%s",
+                                  tls_common_name(mi->context.c2.tls_multi, false),
+                                  mroute_addr_print(&mi->real, &gc),
+                                  mi->context.c2.link_read_bytes,
+                                  mi->context.c2.link_write_bytes,
+                                  time_string(mi->created, 0, false, &gc));
+                }
+                gc_free(&gc);
+            }
+            hash_iterator_free(&hi);
+
+            status_printf(so, "ROUTING TABLE");
+            status_printf(so, "Virtual Address,Common Name,Real Address,Last Ref");
+            hash_iterator_init(m->vhash, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct gc_arena gc = gc_new();
+                const struct multi_route *route = (struct multi_route *) he->value;
+
+                if (multi_route_defined(m, route))
+                {
+                    const struct multi_instance *mi = route->instance;
+                    const struct mroute_addr *ma = &route->addr;
+                    char flags[2] = {0, 0};
+
+                    if (route->flags & MULTI_ROUTE_CACHE)
+                    {
+                        flags[0] = 'C';
+                    }
+                    status_printf(so, "%s%s,%s,%s,%s",
+                                  mroute_addr_print(ma, &gc),
+                                  flags,
+                                  tls_common_name(mi->context.c2.tls_multi, false),
+                                  mroute_addr_print(&mi->real, &gc),
+                                  time_string(route->last_reference, 0, false, &gc));
+                }
+                gc_free(&gc);
+            }
+            hash_iterator_free(&hi);
+
+            status_printf(so, "GLOBAL STATS");
+            if (m->mbuf)
+            {
+                status_printf(so, "Max bcast/mcast queue length,%d",
+                              mbuf_maximum_queued(m->mbuf));
+            }
+
+            status_printf(so, "END");
+        }
+        else if (version == 2 || version == 3)
+        {
+            const char sep = (version == 3) ? '\t' : ',';
+
+            /*
+             * Status file version 2 and 3
+             */
+            status_printf(so, "TITLE%c%s", sep, title_string);
+            status_printf(so, "TIME%c%s%c%u", sep, time_string(now, 0, false, &gc_top), sep, (unsigned int)now);
+            status_printf(so, "HEADER%cCLIENT_LIST%cCommon Name%cReal Address%cVirtual Address%cVirtual IPv6 Address%cBytes Received%cBytes Sent%cConnected Since%cConnected Since (time_t)%cUsername%cClient ID%cPeer ID",
+                          sep, sep, sep, sep, sep, sep, sep, sep, sep, sep, sep, sep);
+            hash_iterator_init(m->hash, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct gc_arena gc = gc_new();
+                const struct multi_instance *mi = (struct multi_instance *) he->value;
+
+                if (!mi->halt)
+                {
+                    status_printf(so, "CLIENT_LIST%c%s%c%s%c%s%c%s%c" counter_format "%c" counter_format "%c%s%c%u%c%s%c"
+#ifdef MANAGEMENT_DEF_AUTH
+                                  "%lu"
+#else
+                                  ""
+#endif
+                                  "%c%" PRIu32,
+                                  sep, tls_common_name(mi->context.c2.tls_multi, false),
+                                  sep, mroute_addr_print(&mi->real, &gc),
+                                  sep, print_in_addr_t(mi->reporting_addr, IA_EMPTY_IF_UNDEF, &gc),
+                                  sep, print_in6_addr(mi->reporting_addr_ipv6, IA_EMPTY_IF_UNDEF, &gc),
+                                  sep, mi->context.c2.link_read_bytes,
+                                  sep, mi->context.c2.link_write_bytes,
+                                  sep, time_string(mi->created, 0, false, &gc),
+                                  sep, (unsigned int)mi->created,
+                                  sep, tls_username(mi->context.c2.tls_multi, false),
+#ifdef MANAGEMENT_DEF_AUTH
+                                  sep, mi->context.c2.mda_context.cid,
+#else
+                                  sep,
+#endif
+                                  sep, mi->context.c2.tls_multi ? mi->context.c2.tls_multi->peer_id : UINT32_MAX);
+                }
+                gc_free(&gc);
+            }
+            hash_iterator_free(&hi);
+
+            status_printf(so, "HEADER%cROUTING_TABLE%cVirtual Address%cCommon Name%cReal Address%cLast Ref%cLast Ref (time_t)",
+                          sep, sep, sep, sep, sep, sep);
+            hash_iterator_init(m->vhash, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct gc_arena gc = gc_new();
+                const struct multi_route *route = (struct multi_route *) he->value;
+
+                if (multi_route_defined(m, route))
+                {
+                    const struct multi_instance *mi = route->instance;
+                    const struct mroute_addr *ma = &route->addr;
+                    char flags[2] = {0, 0};
+
+                    if (route->flags & MULTI_ROUTE_CACHE)
+                    {
+                        flags[0] = 'C';
+                    }
+                    status_printf(so, "ROUTING_TABLE%c%s%s%c%s%c%s%c%s%c%u",
+                                  sep, mroute_addr_print(ma, &gc), flags,
+                                  sep, tls_common_name(mi->context.c2.tls_multi, false),
+                                  sep, mroute_addr_print(&mi->real, &gc),
+                                  sep, time_string(route->last_reference, 0, false, &gc),
+                                  sep, (unsigned int)route->last_reference);
+                }
+                gc_free(&gc);
+            }
+            hash_iterator_free(&hi);
+
+            if (m->mbuf)
+            {
+                status_printf(so, "GLOBAL_STATS%cMax bcast/mcast queue length%c%d",
+                              sep, sep, mbuf_maximum_queued(m->mbuf));
+            }
+
+            status_printf(so, "END");
+        }
+        else
+        {
+            status_printf(so, "ERROR: bad status format version number");
+        }
+
+#ifdef PACKET_TRUNCATION_CHECK
+        {
+            status_printf(so, "HEADER,ERRORS,Common Name,TUN Read Trunc,TUN Write Trunc,Pre-encrypt Trunc,Post-decrypt Trunc");
+            hash_iterator_init(m->hash, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct gc_arena gc = gc_new();
+                const struct multi_instance *mi = (struct multi_instance *) he->value;
+
+                if (!mi->halt)
+                {
+                    status_printf(so, "ERRORS,%s," counter_format "," counter_format "," counter_format "," counter_format,
+                                  tls_common_name(mi->context.c2.tls_multi, false),
+                                  m->top.c2.n_trunc_tun_read,
+                                  mi->context.c2.n_trunc_tun_write,
+                                  mi->context.c2.n_trunc_pre_encrypt,
+                                  mi->context.c2.n_trunc_post_decrypt);
+                }
+                gc_free(&gc);
+            }
+            hash_iterator_free(&hi);
+        }
+#endif /* ifdef PACKET_TRUNCATION_CHECK */
+
+        status_flush(so);
+        gc_free(&gc_top);
+    }
+
+#ifdef ENABLE_ASYNC_PUSH
+    if (m->inotify_watchers)
+    {
+        msg(D_MULTI_DEBUG, "inotify watchers count: %d\n", hash_n_elements(m->inotify_watchers));
+    }
+#endif
+}
+
+/*
+ * Learn a virtual address or route.
+ * The learn will fail if the learn address
+ * script/plugin fails.  In this case the
+ * return value may be != mi.
+ * Return the instance which owns this route,
+ * or NULL if none.
+ */
+static struct multi_instance *
+multi_learn_addr(struct multi_context *m,
+                 struct multi_instance *mi,
+                 const struct mroute_addr *addr,
+                 const unsigned int flags)
+{
+    struct hash_element *he;
+    const uint32_t hv = hash_value(m->vhash, addr);
+    struct hash_bucket *bucket = hash_bucket(m->vhash, hv);
+    struct multi_route *oldroute = NULL;
+    struct multi_instance *owner = NULL;
+    struct gc_arena gc = gc_new();
+
+    /* if route currently exists, get the instance which owns it */
+    he = hash_lookup_fast(m->vhash, bucket, addr, hv);
+    if (he)
+    {
+        oldroute = (struct multi_route *) he->value;
+    }
+    if (oldroute && multi_route_defined(m, oldroute))
+    {
+        owner = oldroute->instance;
+    }
+
+    /* do we need to add address to hash table? */
+    if ((!owner || owner != mi) && mroute_learnable_address(addr, &gc)
+        && !mroute_addr_equal(addr, &m->local))
+    {
+        struct multi_route *newroute;
+        bool learn_succeeded = false;
+
+        ALLOC_OBJ(newroute, struct multi_route);
+        newroute->addr = *addr;
+        newroute->instance = mi;
+        newroute->flags = flags;
+        newroute->last_reference = now;
+        newroute->cache_generation = 0;
+
+        /* The cache is invalidated when cache_generation is incremented */
+        if (flags & MULTI_ROUTE_CACHE)
+        {
+            newroute->cache_generation = m->route_helper->cache_generation;
+        }
+
+        if (oldroute) /* route already exists? */
+        {
+            if (route_quota_test(mi) && learn_address_script(m, mi, "update", &newroute->addr))
+            {
+                learn_succeeded = true;
+                owner = mi;
+                multi_instance_inc_refcount(mi);
+                route_quota_inc(mi);
+
+                /* delete old route */
+                multi_route_del(oldroute);
+
+                /* modify hash table entry, replacing old route */
+                he->key = &newroute->addr;
+                he->value = newroute;
+            }
+        }
+        else
+        {
+            if (route_quota_test(mi) && learn_address_script(m, mi, "add", &newroute->addr))
+            {
+                learn_succeeded = true;
+                owner = mi;
+                multi_instance_inc_refcount(mi);
+                route_quota_inc(mi);
+
+                /* add new route */
+                hash_add_fast(m->vhash, bucket, &newroute->addr, hv, newroute);
+            }
+        }
+
+        msg(D_MULTI_LOW, "MULTI: Learn%s: %s -> %s",
+            learn_succeeded ? "" : " FAILED",
+            mroute_addr_print(&newroute->addr, &gc),
+            multi_instance_string(mi, false, &gc));
+
+        if (!learn_succeeded)
+        {
+            free(newroute);
+        }
+    }
+    gc_free(&gc);
+
+    return owner;
+}
+
+/*
+ * Get client instance based on virtual address.
+ */
+static struct multi_instance *
+multi_get_instance_by_virtual_addr(struct multi_context *m,
+                                   const struct mroute_addr *addr,
+                                   bool cidr_routing)
+{
+    struct multi_route *route;
+    struct multi_instance *ret = NULL;
+
+    /* check for local address */
+    if (mroute_addr_equal(addr, &m->local))
+    {
+        return NULL;
+    }
+
+    route = (struct multi_route *) hash_lookup(m->vhash, addr);
+
+    /* does host route (possible cached) exist? */
+    if (route && multi_route_defined(m, route))
+    {
+        struct multi_instance *mi = route->instance;
+        route->last_reference = now;
+        ret = mi;
+    }
+    else if (cidr_routing) /* do we need to regenerate a host route cache entry? */
+    {
+        struct mroute_helper *rh = m->route_helper;
+        struct mroute_addr tryaddr;
+        int i;
+
+        /* cycle through each CIDR length */
+        for (i = 0; i < rh->n_net_len; ++i)
+        {
+            tryaddr = *addr;
+            tryaddr.type |= MR_WITH_NETBITS;
+            tryaddr.netbits = rh->net_len[i];
+            mroute_addr_mask_host_bits(&tryaddr);
+
+            /* look up a possible route with netbits netmask */
+            route = (struct multi_route *) hash_lookup(m->vhash, &tryaddr);
+
+            if (route && multi_route_defined(m, route))
+            {
+                /* found an applicable route, cache host route */
+                struct multi_instance *mi = route->instance;
+                multi_learn_addr(m, mi, addr, MULTI_ROUTE_CACHE|MULTI_ROUTE_AGEABLE);
+                ret = mi;
+                break;
+            }
+        }
+    }
+
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_MULTI_DEBUG))
+    {
+        struct gc_arena gc = gc_new();
+        const char *addr_text = mroute_addr_print(addr, &gc);
+        if (ret)
+        {
+            dmsg(D_MULTI_DEBUG, "GET INST BY VIRT: %s -> %s via %s",
+                 addr_text,
+                 multi_instance_string(ret, false, &gc),
+                 mroute_addr_print(&route->addr, &gc));
+        }
+        else
+        {
+            dmsg(D_MULTI_DEBUG, "GET INST BY VIRT: %s [failed]",
+                 addr_text);
+        }
+        gc_free(&gc);
+    }
+#endif
+
+    ASSERT(!(ret && ret->halt));
+    return ret;
+}
+
+/*
+ * Helper function to multi_learn_addr().
+ */
+static struct multi_instance *
+multi_learn_in_addr_t(struct multi_context *m,
+                      struct multi_instance *mi,
+                      in_addr_t a,
+                      int netbits,  /* -1 if host route, otherwise # of network bits in address */
+                      bool primary)
+{
+    struct openvpn_sockaddr remote_si;
+    struct mroute_addr addr;
+
+    CLEAR(remote_si);
+    remote_si.addr.in4.sin_family = AF_INET;
+    remote_si.addr.in4.sin_addr.s_addr = htonl(a);
+    ASSERT(mroute_extract_openvpn_sockaddr(&addr, &remote_si, false));
+
+    if (netbits >= 0)
+    {
+        addr.type |= MR_WITH_NETBITS;
+        addr.netbits = (uint8_t) netbits;
+    }
+
+    {
+        struct multi_instance *owner = multi_learn_addr(m, mi, &addr, 0);
+#ifdef MANAGEMENT_DEF_AUTH
+        if (management && owner)
+        {
+            management_learn_addr(management, &mi->context.c2.mda_context, &addr, primary);
+        }
+#endif
+        return owner;
+    }
+}
+
+static struct multi_instance *
+multi_learn_in6_addr(struct multi_context *m,
+                     struct multi_instance *mi,
+                     struct in6_addr a6,
+                     int netbits,   /* -1 if host route, otherwise # of network bits in address */
+                     bool primary)
+{
+    struct mroute_addr addr;
+
+    addr.len = 16;
+    addr.type = MR_ADDR_IPV6;
+    addr.netbits = 0;
+    addr.v6.addr = a6;
+
+    if (netbits >= 0)
+    {
+        addr.type |= MR_WITH_NETBITS;
+        addr.netbits = (uint8_t) netbits;
+        mroute_addr_mask_host_bits( &addr );
+    }
+
+    {
+        struct multi_instance *owner = multi_learn_addr(m, mi, &addr, 0);
+#ifdef MANAGEMENT_DEF_AUTH
+        if (management && owner)
+        {
+            management_learn_addr(management, &mi->context.c2.mda_context, &addr, primary);
+        }
+#endif
+        return owner;
+    }
+}
+
+/*
+ * A new client has connected, add routes (server -> client)
+ * to internal routing table.
+ */
+static void
+multi_add_iroutes(struct multi_context *m,
+                  struct multi_instance *mi)
+{
+    struct gc_arena gc = gc_new();
+    const struct iroute *ir;
+    const struct iroute_ipv6 *ir6;
+    if (TUNNEL_TYPE(mi->context.c1.tuntap) == DEV_TYPE_TUN)
+    {
+        mi->did_iroutes = true;
+        for (ir = mi->context.options.iroutes; ir != NULL; ir = ir->next)
+        {
+            if (ir->netbits >= 0)
+            {
+                msg(D_MULTI_LOW, "MULTI: internal route %s/%d -> %s",
+                    print_in_addr_t(ir->network, 0, &gc),
+                    ir->netbits,
+                    multi_instance_string(mi, false, &gc));
+            }
+            else
+            {
+                msg(D_MULTI_LOW, "MULTI: internal route %s -> %s",
+                    print_in_addr_t(ir->network, 0, &gc),
+                    multi_instance_string(mi, false, &gc));
+            }
+
+            mroute_helper_add_iroute46(m->route_helper, ir->netbits);
+
+            multi_learn_in_addr_t(m, mi, ir->network, ir->netbits, false);
+        }
+        for (ir6 = mi->context.options.iroutes_ipv6; ir6 != NULL; ir6 = ir6->next)
+        {
+            msg(D_MULTI_LOW, "MULTI: internal route %s/%d -> %s",
+                print_in6_addr(ir6->network, 0, &gc),
+                ir6->netbits,
+                multi_instance_string(mi, false, &gc));
+
+            mroute_helper_add_iroute46(m->route_helper, ir6->netbits);
+
+            multi_learn_in6_addr(m, mi, ir6->network, ir6->netbits, false);
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Given an instance (new_mi), delete all other instances which use the
+ * same common name.
+ */
+static void
+multi_delete_dup(struct multi_context *m, struct multi_instance *new_mi)
+{
+    if (new_mi)
+    {
+        const char *new_cn = tls_common_name(new_mi->context.c2.tls_multi, true);
+        if (new_cn)
+        {
+            struct hash_iterator hi;
+            struct hash_element *he;
+            int count = 0;
+
+            hash_iterator_init(m->iter, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct multi_instance *mi = (struct multi_instance *) he->value;
+                if (mi != new_mi && !mi->halt)
+                {
+                    const char *cn = tls_common_name(mi->context.c2.tls_multi, true);
+                    if (cn && !strcmp(cn, new_cn))
+                    {
+                        mi->did_iter = false;
+                        multi_close_instance(m, mi, false);
+                        hash_iterator_delete_element(&hi);
+                        ++count;
+                    }
+                }
+            }
+            hash_iterator_free(&hi);
+
+            if (count)
+            {
+                msg(D_MULTI_LOW, "MULTI: new connection by client '%s' will cause previous active sessions by this client to be dropped.  Remember to use the --duplicate-cn option if you want multiple clients using the same certificate or username to concurrently connect.", new_cn);
+            }
+        }
+    }
+}
+
+static void
+check_stale_routes(struct multi_context *m)
+{
+
+    struct gc_arena gc = gc_new();
+    struct hash_iterator hi;
+    struct hash_element *he;
+
+    dmsg(D_MULTI_DEBUG, "MULTI: Checking stale routes");
+    hash_iterator_init_range(m->vhash, &hi, 0, hash_n_buckets(m->vhash));
+    while ((he = hash_iterator_next(&hi)) != NULL)
+    {
+        struct multi_route *r = (struct multi_route *) he->value;
+        if (multi_route_defined(m, r) && difftime(now, r->last_reference) >= m->top.options.stale_routes_ageing_time)
+        {
+            dmsg(D_MULTI_DEBUG, "MULTI: Deleting stale route for address '%s'",
+                 mroute_addr_print(&r->addr, &gc));
+            learn_address_script(m, NULL, "delete", &r->addr);
+            multi_route_del(r);
+            hash_iterator_delete_element(&hi);
+        }
+    }
+    hash_iterator_free(&hi);
+    gc_free(&gc);
+}
+
+/*
+ * Ensure that endpoint to be pushed to client
+ * complies with --ifconfig-push-constraint directive.
+ */
+static bool
+ifconfig_push_constraint_satisfied(const struct context *c)
+{
+    const struct options *o = &c->options;
+    if (o->push_ifconfig_constraint_defined && c->c2.push_ifconfig_defined)
+    {
+        return (o->push_ifconfig_constraint_netmask & c->c2.push_ifconfig_local) == o->push_ifconfig_constraint_network;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Select a virtual address for a new client instance.
+ * Use an --ifconfig-push directive, if given (static IP).
+ * Otherwise use an --ifconfig-pool address (dynamic IP).
+ */
+static void
+multi_select_virtual_addr(struct multi_context *m, struct multi_instance *mi)
+{
+    struct gc_arena gc = gc_new();
+
+    /*
+     * If ifconfig addresses were set by dynamic config file,
+     * release pool addresses, otherwise keep them.
+     */
+    if (mi->context.options.push_ifconfig_defined)
+    {
+        /* ifconfig addresses were set statically,
+         * release dynamic allocation */
+        if (mi->vaddr_handle >= 0)
+        {
+            ifconfig_pool_release(m->ifconfig_pool, mi->vaddr_handle, true);
+            mi->vaddr_handle = -1;
+        }
+
+        mi->context.c2.push_ifconfig_defined = true;
+        mi->context.c2.push_ifconfig_local = mi->context.options.push_ifconfig_local;
+        mi->context.c2.push_ifconfig_remote_netmask = mi->context.options.push_ifconfig_remote_netmask;
+        mi->context.c2.push_ifconfig_local_alias = mi->context.options.push_ifconfig_local_alias;
+
+        /* the current implementation does not allow "static IPv4, pool IPv6",
+         * (see below) so issue a warning if that happens - don't break the
+         * session, though, as we don't even know if this client WANTS IPv6
+         */
+        if (mi->context.options.ifconfig_ipv6_pool_defined
+            && !mi->context.options.push_ifconfig_ipv6_defined)
+        {
+            msg( M_INFO, "MULTI_sva: WARNING: if --ifconfig-push is used for IPv4, automatic IPv6 assignment from --ifconfig-ipv6-pool does not work.  Use --ifconfig-ipv6-push for IPv6 then." );
+        }
+    }
+    else if (m->ifconfig_pool && mi->vaddr_handle < 0) /* otherwise, choose a pool address */
+    {
+        in_addr_t local = 0, remote = 0;
+        struct in6_addr remote_ipv6;
+        const char *cn = NULL;
+
+        if (!mi->context.options.duplicate_cn)
+        {
+            cn = tls_common_name(mi->context.c2.tls_multi, true);
+        }
+
+        CLEAR(remote_ipv6);
+        mi->vaddr_handle = ifconfig_pool_acquire(m->ifconfig_pool, &local, &remote, &remote_ipv6, cn);
+        if (mi->vaddr_handle >= 0)
+        {
+            const int tunnel_type = TUNNEL_TYPE(mi->context.c1.tuntap);
+            const int tunnel_topology = TUNNEL_TOPOLOGY(mi->context.c1.tuntap);
+
+            msg( M_INFO, "MULTI_sva: pool returned IPv4=%s, IPv6=%s",
+                 print_in_addr_t( remote, 0, &gc ),
+                 (mi->context.options.ifconfig_ipv6_pool_defined
+                  ? print_in6_addr( remote_ipv6, 0, &gc )
+                  : "(Not enabled)") );
+
+            /* set push_ifconfig_remote_netmask from pool ifconfig address(es) */
+            mi->context.c2.push_ifconfig_local = remote;
+            if (tunnel_type == DEV_TYPE_TAP || (tunnel_type == DEV_TYPE_TUN && tunnel_topology == TOP_SUBNET))
+            {
+                mi->context.c2.push_ifconfig_remote_netmask = mi->context.options.ifconfig_pool_netmask;
+                if (!mi->context.c2.push_ifconfig_remote_netmask)
+                {
+                    mi->context.c2.push_ifconfig_remote_netmask = mi->context.c1.tuntap->remote_netmask;
+                }
+            }
+            else if (tunnel_type == DEV_TYPE_TUN)
+            {
+                if (tunnel_topology == TOP_P2P)
+                {
+                    mi->context.c2.push_ifconfig_remote_netmask = mi->context.c1.tuntap->local;
+                }
+                else if (tunnel_topology == TOP_NET30)
+                {
+                    mi->context.c2.push_ifconfig_remote_netmask = local;
+                }
+            }
+
+            if (mi->context.c2.push_ifconfig_remote_netmask)
+            {
+                mi->context.c2.push_ifconfig_defined = true;
+            }
+            else
+            {
+                msg(D_MULTI_ERRORS, "MULTI: no --ifconfig-pool netmask parameter is available to push to %s",
+                    multi_instance_string(mi, false, &gc));
+            }
+
+            if (mi->context.options.ifconfig_ipv6_pool_defined)
+            {
+                mi->context.c2.push_ifconfig_ipv6_local = remote_ipv6;
+                mi->context.c2.push_ifconfig_ipv6_remote =
+                    mi->context.c1.tuntap->local_ipv6;
+                mi->context.c2.push_ifconfig_ipv6_netbits =
+                    mi->context.options.ifconfig_ipv6_netbits;
+                mi->context.c2.push_ifconfig_ipv6_defined = true;
+            }
+        }
+        else
+        {
+            msg(D_MULTI_ERRORS, "MULTI: no free --ifconfig-pool addresses are available");
+        }
+    }
+
+    /* IPv6 push_ifconfig is a bit problematic - since IPv6 shares the
+     * pool handling with IPv4, the combination "static IPv4, dynamic IPv6"
+     * will fail (because no pool will be allocated in this case).
+     * OTOH, this doesn't make too much sense in reality - and the other
+     * way round ("dynamic IPv4, static IPv6") or "both static" makes sense
+     * -> and so it's implemented right now
+     */
+    if (mi->context.options.push_ifconfig_ipv6_defined)
+    {
+        mi->context.c2.push_ifconfig_ipv6_local =
+            mi->context.options.push_ifconfig_ipv6_local;
+        mi->context.c2.push_ifconfig_ipv6_remote =
+            mi->context.options.push_ifconfig_ipv6_remote;
+        mi->context.c2.push_ifconfig_ipv6_netbits =
+            mi->context.options.push_ifconfig_ipv6_netbits;
+        mi->context.c2.push_ifconfig_ipv6_defined = true;
+
+        msg( M_INFO, "MULTI_sva: push_ifconfig_ipv6 %s/%d",
+             print_in6_addr( mi->context.c2.push_ifconfig_ipv6_local, 0, &gc ),
+             mi->context.c2.push_ifconfig_ipv6_netbits );
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Set virtual address environmental variables.
+ */
+static void
+multi_set_virtual_addr_env(struct multi_instance *mi)
+{
+    setenv_del(mi->context.c2.es, "ifconfig_pool_local_ip");
+    setenv_del(mi->context.c2.es, "ifconfig_pool_remote_ip");
+    setenv_del(mi->context.c2.es, "ifconfig_pool_netmask");
+
+    if (mi->context.c2.push_ifconfig_defined)
+    {
+        const int tunnel_type = TUNNEL_TYPE(mi->context.c1.tuntap);
+        const int tunnel_topology = TUNNEL_TOPOLOGY(mi->context.c1.tuntap);
+
+        setenv_in_addr_t(mi->context.c2.es,
+                         "ifconfig_pool_remote_ip",
+                         mi->context.c2.push_ifconfig_local,
+                         SA_SET_IF_NONZERO);
+
+        if (tunnel_type == DEV_TYPE_TAP || (tunnel_type == DEV_TYPE_TUN && tunnel_topology == TOP_SUBNET))
+        {
+            setenv_in_addr_t(mi->context.c2.es,
+                             "ifconfig_pool_netmask",
+                             mi->context.c2.push_ifconfig_remote_netmask,
+                             SA_SET_IF_NONZERO);
+        }
+        else if (tunnel_type == DEV_TYPE_TUN)
+        {
+            setenv_in_addr_t(mi->context.c2.es,
+                             "ifconfig_pool_local_ip",
+                             mi->context.c2.push_ifconfig_remote_netmask,
+                             SA_SET_IF_NONZERO);
+        }
+    }
+
+    setenv_del(mi->context.c2.es, "ifconfig_pool_local_ip6");
+    setenv_del(mi->context.c2.es, "ifconfig_pool_remote_ip6");
+    setenv_del(mi->context.c2.es, "ifconfig_pool_ip6_netbits");
+
+    if (mi->context.c2.push_ifconfig_ipv6_defined)
+    {
+        setenv_in6_addr(mi->context.c2.es,
+                        "ifconfig_pool_remote",
+                        &mi->context.c2.push_ifconfig_ipv6_local,
+                        SA_SET_IF_NONZERO);
+        setenv_in6_addr(mi->context.c2.es,
+                        "ifconfig_pool_local",
+                        &mi->context.c2.push_ifconfig_ipv6_remote,
+                        SA_SET_IF_NONZERO);
+        setenv_int(mi->context.c2.es,
+                   "ifconfig_pool_ip6_netbits",
+                   mi->context.c2.push_ifconfig_ipv6_netbits);
+    }
+}
+
+/*
+ * Called after client-connect script is called
+ */
+static void
+multi_client_connect_post(struct multi_context *m,
+                          struct multi_instance *mi,
+                          const char *dc_file,
+                          unsigned int option_permissions_mask,
+                          unsigned int *option_types_found)
+{
+    /* Did script generate a dynamic config file? */
+    if (test_file(dc_file))
+    {
+        options_server_import(&mi->context.options,
+                              dc_file,
+                              D_IMPORT_ERRORS|M_OPTERR,
+                              option_permissions_mask,
+                              option_types_found,
+                              mi->context.c2.es);
+
+        /*
+         * If the --client-connect script generates a config file
+         * with an --ifconfig-push directive, it will override any
+         * --ifconfig-push directive from the --client-config-dir
+         * directory or any --ifconfig-pool dynamic address.
+         */
+        multi_select_virtual_addr(m, mi);
+        multi_set_virtual_addr_env(mi);
+    }
+}
+
+#ifdef ENABLE_PLUGIN
+
+/*
+ * Called after client-connect plug-in is called
+ */
+static void
+multi_client_connect_post_plugin(struct multi_context *m,
+                                 struct multi_instance *mi,
+                                 const struct plugin_return *pr,
+                                 unsigned int option_permissions_mask,
+                                 unsigned int *option_types_found)
+{
+    struct plugin_return config;
+
+    plugin_return_get_column(pr, &config, "config");
+
+    /* Did script generate a dynamic config file? */
+    if (plugin_return_defined(&config))
+    {
+        int i;
+        for (i = 0; i < config.n; ++i)
+        {
+            if (config.list[i] && config.list[i]->value)
+            {
+                options_string_import(&mi->context.options,
+                                      config.list[i]->value,
+                                      D_IMPORT_ERRORS|M_OPTERR,
+                                      option_permissions_mask,
+                                      option_types_found,
+                                      mi->context.c2.es);
+            }
+        }
+
+        /*
+         * If the --client-connect script generates a config file
+         * with an --ifconfig-push directive, it will override any
+         * --ifconfig-push directive from the --client-config-dir
+         * directory or any --ifconfig-pool dynamic address.
+         */
+        multi_select_virtual_addr(m, mi);
+        multi_set_virtual_addr_env(mi);
+    }
+}
+
+#endif /* ifdef ENABLE_PLUGIN */
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+/*
+ * Called to load management-derived client-connect config
+ */
+static void
+multi_client_connect_mda(struct multi_context *m,
+                         struct multi_instance *mi,
+                         const struct buffer_list *config,
+                         unsigned int option_permissions_mask,
+                         unsigned int *option_types_found)
+{
+    if (config)
+    {
+        struct buffer_entry *be;
+
+        for (be = config->head; be != NULL; be = be->next)
+        {
+            const char *opt = BSTR(&be->buf);
+            options_string_import(&mi->context.options,
+                                  opt,
+                                  D_IMPORT_ERRORS|M_OPTERR,
+                                  option_permissions_mask,
+                                  option_types_found,
+                                  mi->context.c2.es);
+        }
+
+        /*
+         * If the --client-connect script generates a config file
+         * with an --ifconfig-push directive, it will override any
+         * --ifconfig-push directive from the --client-config-dir
+         * directory or any --ifconfig-pool dynamic address.
+         */
+        multi_select_virtual_addr(m, mi);
+        multi_set_virtual_addr_env(mi);
+    }
+}
+
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+
+static void
+multi_client_connect_setenv(struct multi_context *m,
+                            struct multi_instance *mi)
+{
+    struct gc_arena gc = gc_new();
+
+    /* setenv incoming cert common name for script */
+    setenv_str(mi->context.c2.es, "common_name", tls_common_name(mi->context.c2.tls_multi, true));
+
+    /* setenv client real IP address */
+    setenv_trusted(mi->context.c2.es, get_link_socket_info(&mi->context));
+
+    /* setenv client virtual IP address */
+    multi_set_virtual_addr_env(mi);
+
+    /* setenv connection time */
+    {
+        const char *created_ascii = time_string(mi->created, 0, false, &gc);
+        setenv_str(mi->context.c2.es, "time_ascii", created_ascii);
+        setenv_unsigned(mi->context.c2.es, "time_unix", (unsigned int)mi->created);
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Called as soon as the SSL/TLS connection authenticates.
+ *
+ * Instance-specific directives to be processed:
+ *
+ *   iroute start-ip end-ip
+ *   ifconfig-push local remote-netmask
+ *   push
+ */
+static void
+multi_connection_established(struct multi_context *m, struct multi_instance *mi)
+{
+    if (tls_authentication_status(mi->context.c2.tls_multi, 0) == TLS_AUTHENTICATION_SUCCEEDED)
+    {
+        struct gc_arena gc = gc_new();
+        unsigned int option_types_found = 0;
+
+        const unsigned int option_permissions_mask =
+            OPT_P_INSTANCE
+            | OPT_P_INHERIT
+            | OPT_P_PUSH
+            | OPT_P_TIMER
+            | OPT_P_CONFIG
+            | OPT_P_ECHO
+            | OPT_P_COMP
+            | OPT_P_SOCKFLAGS;
+
+        int cc_succeeded = true; /* client connect script status */
+        int cc_succeeded_count = 0;
+
+        ASSERT(mi->context.c1.tuntap);
+
+        /* lock down the common name and cert hashes so they can't change during future TLS renegotiations */
+        tls_lock_common_name(mi->context.c2.tls_multi);
+        tls_lock_cert_hash_set(mi->context.c2.tls_multi);
+
+        /* generate a msg() prefix for this client instance */
+        generate_prefix(mi);
+
+        /* delete instances of previous clients with same common-name */
+        if (!mi->context.options.duplicate_cn)
+        {
+            multi_delete_dup(m, mi);
+        }
+
+        /* reset pool handle to null */
+        mi->vaddr_handle = -1;
+
+        /*
+         * Try to source a dynamic config file from the
+         * --client-config-dir directory.
+         */
+        if (mi->context.options.client_config_dir)
+        {
+            const char *ccd_file;
+
+            ccd_file = gen_path(mi->context.options.client_config_dir,
+                                tls_common_name(mi->context.c2.tls_multi, false),
+                                &gc);
+
+            /* try common-name file */
+            if (test_file(ccd_file))
+            {
+                options_server_import(&mi->context.options,
+                                      ccd_file,
+                                      D_IMPORT_ERRORS|M_OPTERR,
+                                      option_permissions_mask,
+                                      &option_types_found,
+                                      mi->context.c2.es);
+            }
+            else /* try default file */
+            {
+                ccd_file = gen_path(mi->context.options.client_config_dir,
+                                    CCD_DEFAULT,
+                                    &gc);
+
+                if (test_file(ccd_file))
+                {
+                    options_server_import(&mi->context.options,
+                                          ccd_file,
+                                          D_IMPORT_ERRORS|M_OPTERR,
+                                          option_permissions_mask,
+                                          &option_types_found,
+                                          mi->context.c2.es);
+                }
+            }
+        }
+
+        /*
+         * Select a virtual address from either --ifconfig-push in --client-config-dir file
+         * or --ifconfig-pool.
+         */
+        multi_select_virtual_addr(m, mi);
+
+        /* do --client-connect setenvs */
+        multi_client_connect_setenv(m, mi);
+
+#ifdef ENABLE_PLUGIN
+        /*
+         * Call client-connect plug-in.
+         */
+
+        /* deprecated callback, use a file for passing back return info */
+        if (plugin_defined(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_CONNECT))
+        {
+            struct argv argv = argv_new();
+            const char *dc_file = create_temp_file(mi->context.options.tmp_dir, "cc", &gc);
+
+            if (!dc_file)
+            {
+                cc_succeeded = false;
+                goto script_depr_failed;
+            }
+
+            argv_printf(&argv, "%s", dc_file);
+            if (plugin_call(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_CONNECT, &argv, NULL, mi->context.c2.es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+            {
+                msg(M_WARN, "WARNING: client-connect plugin call failed");
+                cc_succeeded = false;
+            }
+            else
+            {
+                multi_client_connect_post(m, mi, dc_file, option_permissions_mask, &option_types_found);
+                ++cc_succeeded_count;
+            }
+
+            if (!platform_unlink(dc_file))
+            {
+                msg(D_MULTI_ERRORS, "MULTI: problem deleting temporary file: %s",
+                    dc_file);
+            }
+
+script_depr_failed:
+            argv_reset(&argv);
+        }
+
+        /* V2 callback, use a plugin_return struct for passing back return info */
+        if (plugin_defined(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_CONNECT_V2))
+        {
+            struct plugin_return pr;
+
+            plugin_return_init(&pr);
+
+            if (plugin_call(mi->context.plugins, OPENVPN_PLUGIN_CLIENT_CONNECT_V2, NULL, &pr, mi->context.c2.es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+            {
+                msg(M_WARN, "WARNING: client-connect-v2 plugin call failed");
+                cc_succeeded = false;
+            }
+            else
+            {
+                multi_client_connect_post_plugin(m, mi, &pr, option_permissions_mask, &option_types_found);
+                ++cc_succeeded_count;
+            }
+
+            plugin_return_free(&pr);
+        }
+#endif /* ifdef ENABLE_PLUGIN */
+
+        /*
+         * Run --client-connect script.
+         */
+        if (mi->context.options.client_connect_script && cc_succeeded)
+        {
+            struct argv argv = argv_new();
+            const char *dc_file = NULL;
+
+            setenv_str(mi->context.c2.es, "script_type", "client-connect");
+
+            dc_file = create_temp_file(mi->context.options.tmp_dir, "cc", &gc);
+            if (!dc_file)
+            {
+                cc_succeeded = false;
+                goto script_failed;
+            }
+
+            argv_parse_cmd(&argv, mi->context.options.client_connect_script);
+            argv_printf_cat(&argv, "%s", dc_file);
+
+            if (openvpn_run_script(&argv, mi->context.c2.es, 0, "--client-connect"))
+            {
+                multi_client_connect_post(m, mi, dc_file, option_permissions_mask, &option_types_found);
+                ++cc_succeeded_count;
+            }
+            else
+            {
+                cc_succeeded = false;
+            }
+
+            if (!platform_unlink(dc_file))
+            {
+                msg(D_MULTI_ERRORS, "MULTI: problem deleting temporary file: %s",
+                    dc_file);
+            }
+
+script_failed:
+            argv_reset(&argv);
+        }
+
+        /*
+         * Check for client-connect script left by management interface client
+         */
+#ifdef MANAGEMENT_DEF_AUTH
+        if (cc_succeeded && mi->cc_config)
+        {
+            multi_client_connect_mda(m, mi, mi->cc_config, option_permissions_mask, &option_types_found);
+            ++cc_succeeded_count;
+        }
+#endif
+
+        /*
+         * Check for "disable" directive in client-config-dir file
+         * or config file generated by --client-connect script.
+         */
+        if (mi->context.options.disable)
+        {
+            msg(D_MULTI_ERRORS, "MULTI: client has been rejected due to 'disable' directive");
+            cc_succeeded = false;
+            cc_succeeded_count = 0;
+        }
+
+        if (cc_succeeded)
+        {
+            /*
+             * Process sourced options.
+             */
+            do_deferred_options(&mi->context, option_types_found);
+
+            /*
+             * make sure we got ifconfig settings from somewhere
+             */
+            if (!mi->context.c2.push_ifconfig_defined)
+            {
+                msg(D_MULTI_ERRORS, "MULTI: no dynamic or static remote --ifconfig address is available for %s",
+                    multi_instance_string(mi, false, &gc));
+            }
+
+            /*
+             * make sure that ifconfig settings comply with constraints
+             */
+            if (!ifconfig_push_constraint_satisfied(&mi->context))
+            {
+                /* JYFIXME -- this should cause the connection to fail */
+                msg(D_MULTI_ERRORS, "MULTI ERROR: primary virtual IP for %s (%s) violates tunnel network/netmask constraint (%s/%s)",
+                    multi_instance_string(mi, false, &gc),
+                    print_in_addr_t(mi->context.c2.push_ifconfig_local, 0, &gc),
+                    print_in_addr_t(mi->context.options.push_ifconfig_constraint_network, 0, &gc),
+                    print_in_addr_t(mi->context.options.push_ifconfig_constraint_netmask, 0, &gc));
+            }
+
+            /*
+             * For routed tunnels, set up internal route to endpoint
+             * plus add all iroute routes.
+             */
+            if (TUNNEL_TYPE(mi->context.c1.tuntap) == DEV_TYPE_TUN)
+            {
+                if (mi->context.c2.push_ifconfig_defined)
+                {
+                    multi_learn_in_addr_t(m, mi, mi->context.c2.push_ifconfig_local, -1, true);
+                    msg(D_MULTI_LOW, "MULTI: primary virtual IP for %s: %s",
+                        multi_instance_string(mi, false, &gc),
+                        print_in_addr_t(mi->context.c2.push_ifconfig_local, 0, &gc));
+                }
+
+                if (mi->context.c2.push_ifconfig_ipv6_defined)
+                {
+                    multi_learn_in6_addr(m, mi, mi->context.c2.push_ifconfig_ipv6_local, -1, true);
+                    /* TODO: find out where addresses are "unlearned"!! */
+                    msg(D_MULTI_LOW, "MULTI: primary virtual IPv6 for %s: %s",
+                        multi_instance_string(mi, false, &gc),
+                        print_in6_addr(mi->context.c2.push_ifconfig_ipv6_local, 0, &gc));
+                }
+
+                /* add routes locally, pointing to new client, if
+                 * --iroute options have been specified */
+                multi_add_iroutes(m, mi);
+
+                /*
+                 * iroutes represent subnets which are "owned" by a particular
+                 * client.  Therefore, do not actually push a route to a client
+                 * if it matches one of the client's iroutes.
+                 */
+                remove_iroutes_from_push_route_list(&mi->context.options);
+            }
+            else if (mi->context.options.iroutes)
+            {
+                msg(D_MULTI_ERRORS, "MULTI: --iroute options rejected for %s -- iroute only works with tun-style tunnels",
+                    multi_instance_string(mi, false, &gc));
+            }
+
+            /* set our client's VPN endpoint for status reporting purposes */
+            mi->reporting_addr = mi->context.c2.push_ifconfig_local;
+            mi->reporting_addr_ipv6 = mi->context.c2.push_ifconfig_ipv6_local;
+
+            /* set context-level authentication flag */
+            mi->context.c2.context_auth = CAS_SUCCEEDED;
+
+#ifdef ENABLE_ASYNC_PUSH
+            /* authentication complete, send push reply */
+            if (mi->context.c2.push_request_received)
+            {
+                process_incoming_push_request(&mi->context);
+            }
+#endif
+        }
+        else
+        {
+            /* set context-level authentication flag */
+            mi->context.c2.context_auth = cc_succeeded_count ? CAS_PARTIAL : CAS_FAILED;
+        }
+
+        /* set flag so we don't get called again */
+        mi->connection_established_flag = true;
+
+        /* increment number of current authenticated clients */
+        ++m->n_clients;
+        update_mstat_n_clients(m->n_clients);
+        --mi->n_clients_delta;
+
+#ifdef MANAGEMENT_DEF_AUTH
+        if (management)
+        {
+            management_connection_established(management, &mi->context.c2.mda_context, mi->context.c2.es);
+        }
+#endif
+
+        gc_free(&gc);
+    }
+
+    /*
+     * Reply now to client's PUSH_REQUEST query
+     */
+    mi->context.c2.push_reply_deferred = false;
+}
+
+#ifdef ENABLE_ASYNC_PUSH
+/*
+ * Called when inotify event is fired, which happens when acf file is closed or deleted.
+ * Continues authentication and sends push_reply.
+ */
+void
+multi_process_file_closed(struct multi_context *m, const unsigned int mpp_flags)
+{
+    char buffer[INOTIFY_EVENT_BUFFER_SIZE];
+    size_t buffer_i = 0;
+    int r = read(m->top.c2.inotify_fd, buffer, INOTIFY_EVENT_BUFFER_SIZE);
+
+    while (buffer_i < r)
+    {
+        /* parse inotify events */
+        struct inotify_event *pevent = (struct inotify_event *) &buffer[buffer_i];
+        size_t event_size = sizeof(struct inotify_event) + pevent->len;
+        buffer_i += event_size;
+
+        msg(D_MULTI_DEBUG, "MULTI: modified fd %d, mask %d", pevent->wd, pevent->mask);
+
+        struct multi_instance *mi = hash_lookup(m->inotify_watchers, (void *) (unsigned long) pevent->wd);
+
+        if (pevent->mask & IN_CLOSE_WRITE)
+        {
+            if (mi)
+            {
+                /* continue authentication, perform NCP negotiation and send push_reply */
+                multi_process_post(m, mi, mpp_flags);
+
+                /* With NCP and deferred authentication, we perform cipher negotiation and
+                 * data channel keys generation on incoming push request, assuming that auth
+                 * succeeded. When auth succeeds in between push requests and async push is used,
+                 * we send push reply immediately. Above multi_process_post() call performs
+                 * NCP negotiation and here we do keys generation. */
+
+                struct context *c = &mi->context;
+                struct frame *frame_fragment = NULL;
+#ifdef ENABLE_FRAGMENT
+                if (c->options.ce.fragment)
+                {
+                    frame_fragment = &c->c2.frame_fragment;
+                }
+#endif
+                struct tls_session *session = &c->c2.tls_multi->session[TM_ACTIVE];
+                if (!tls_session_update_crypto_params(session, &c->options,
+                                                      &c->c2.frame, frame_fragment))
+                {
+                    msg(D_TLS_ERRORS, "TLS Error: initializing data channel failed");
+                    register_signal(c, SIGUSR1, "init-data-channel-failed");
+                }
+            }
+            else
+            {
+                msg(D_MULTI_ERRORS, "MULTI: multi_instance not found!");
+            }
+        }
+        else if (pevent->mask & IN_IGNORED)
+        {
+            /* this event is _always_ fired when watch is removed or file is deleted */
+            if (mi)
+            {
+                hash_remove(m->inotify_watchers, (void *) (unsigned long) pevent->wd);
+                mi->inotify_watch = -1;
+            }
+        }
+        else
+        {
+            msg(D_MULTI_ERRORS, "MULTI: unknown mask %d", pevent->mask);
+        }
+    }
+}
+#endif /* ifdef ENABLE_ASYNC_PUSH */
+
+/*
+ * Add a mbuf buffer to a particular
+ * instance.
+ */
+void
+multi_add_mbuf(struct multi_context *m,
+               struct multi_instance *mi,
+               struct mbuf_buffer *mb)
+{
+    if (multi_output_queue_ready(m, mi))
+    {
+        struct mbuf_item item;
+        item.buffer = mb;
+        item.instance = mi;
+        mbuf_add_item(m->mbuf, &item);
+    }
+    else
+    {
+        msg(D_MULTI_DROPPED, "MULTI: packet dropped due to output saturation (multi_add_mbuf)");
+    }
+}
+
+/*
+ * Add a packet to a client instance output queue.
+ */
+static inline void
+multi_unicast(struct multi_context *m,
+              const struct buffer *buf,
+              struct multi_instance *mi)
+{
+    struct mbuf_buffer *mb;
+
+    if (BLEN(buf) > 0)
+    {
+        mb = mbuf_alloc_buf(buf);
+        mb->flags = MF_UNICAST;
+        multi_add_mbuf(m, mi, mb);
+        mbuf_free_buf(mb);
+    }
+}
+
+/*
+ * Broadcast a packet to all clients.
+ */
+static void
+multi_bcast(struct multi_context *m,
+            const struct buffer *buf,
+            const struct multi_instance *sender_instance,
+            const struct mroute_addr *sender_addr)
+{
+    struct hash_iterator hi;
+    struct hash_element *he;
+    struct multi_instance *mi;
+    struct mbuf_buffer *mb;
+
+    if (BLEN(buf) > 0)
+    {
+        perf_push(PERF_MULTI_BCAST);
+#ifdef MULTI_DEBUG_EVENT_LOOP
+        printf("BCAST len=%d\n", BLEN(buf));
+#endif
+        mb = mbuf_alloc_buf(buf);
+        hash_iterator_init(m->iter, &hi);
+
+        while ((he = hash_iterator_next(&hi)))
+        {
+            mi = (struct multi_instance *) he->value;
+            if (mi != sender_instance && !mi->halt)
+            {
+#ifdef ENABLE_PF
+                if (sender_instance)
+                {
+                    if (!pf_c2c_test(&sender_instance->context, &mi->context, "bcast_c2c"))
+                    {
+                        msg(D_PF_DROPPED_BCAST, "PF: client[%s] -> client[%s] packet dropped by BCAST packet filter",
+                            mi_prefix(sender_instance),
+                            mi_prefix(mi));
+                        continue;
+                    }
+                }
+                if (sender_addr)
+                {
+                    if (!pf_addr_test(&mi->context, sender_addr, "bcast_src_addr"))
+                    {
+                        struct gc_arena gc = gc_new();
+                        msg(D_PF_DROPPED_BCAST, "PF: addr[%s] -> client[%s] packet dropped by BCAST packet filter",
+                            mroute_addr_print_ex(sender_addr, MAPF_SHOW_ARP, &gc),
+                            mi_prefix(mi));
+                        gc_free(&gc);
+                        continue;
+                    }
+                }
+#endif /* ifdef ENABLE_PF */
+                multi_add_mbuf(m, mi, mb);
+            }
+        }
+
+        hash_iterator_free(&hi);
+        mbuf_free_buf(mb);
+        perf_pop();
+    }
+}
+
+/*
+ * Given a time delta, indicating that we wish to be
+ * awoken by the scheduler at time now + delta, figure
+ * a sigma parameter (in microseconds) that represents
+ * a sort of fuzz factor around delta, so that we're
+ * really telling the scheduler to wake us up any time
+ * between now + delta - sigma and now + delta + sigma.
+ *
+ * The sigma parameter helps the scheduler to run more efficiently.
+ * Sigma should be no larger than TV_WITHIN_SIGMA_MAX_USEC
+ */
+static inline unsigned int
+compute_wakeup_sigma(const struct timeval *delta)
+{
+    if (delta->tv_sec < 1)
+    {
+        /* if < 1 sec, fuzz = # of microseconds / 8 */
+        return delta->tv_usec >> 3;
+    }
+    else
+    {
+        /* if < 10 minutes, fuzz = 13.1% of timeout */
+        if (delta->tv_sec < 600)
+        {
+            return delta->tv_sec << 17;
+        }
+        else
+        {
+            return 120000000; /* if >= 10 minutes, fuzz = 2 minutes */
+        }
+    }
+}
+
+static void
+multi_schedule_context_wakeup(struct multi_context *m, struct multi_instance *mi)
+{
+    /* calculate an absolute wakeup time */
+    ASSERT(!openvpn_gettimeofday(&mi->wakeup, NULL));
+    tv_add(&mi->wakeup, &mi->context.c2.timeval);
+
+    /* tell scheduler to wake us up at some point in the future */
+    schedule_add_entry(m->schedule,
+                       (struct schedule_entry *) mi,
+                       &mi->wakeup,
+                       compute_wakeup_sigma(&mi->context.c2.timeval));
+}
+
+/*
+ * Figure instance-specific timers, convert
+ * earliest to absolute time in mi->wakeup,
+ * call scheduler with our future wakeup time.
+ *
+ * Also close context on signal.
+ */
+bool
+multi_process_post(struct multi_context *m, struct multi_instance *mi, const unsigned int flags)
+{
+    bool ret = true;
+
+    if (!IS_SIG(&mi->context) && ((flags & MPP_PRE_SELECT) || ((flags & MPP_CONDITIONAL_PRE_SELECT) && !ANY_OUT(&mi->context))))
+    {
+#if defined(ENABLE_ASYNC_PUSH) && defined(ENABLE_DEF_AUTH)
+        bool was_authenticated = false;
+        struct key_state *ks = NULL;
+        if (mi->context.c2.tls_multi)
+        {
+            ks = &mi->context.c2.tls_multi->session[TM_ACTIVE].key[KS_PRIMARY];
+            was_authenticated = ks->authenticated;
+        }
+#endif
+
+        /* figure timeouts and fetch possible outgoing
+         * to_link packets (such as ping or TLS control) */
+        pre_select(&mi->context);
+
+#if defined(ENABLE_ASYNC_PUSH) && defined(ENABLE_DEF_AUTH)
+        if (ks && ks->auth_control_file && ks->auth_deferred && !was_authenticated)
+        {
+            /* watch acf file */
+            long watch_descriptor = inotify_add_watch(m->top.c2.inotify_fd, ks->auth_control_file, IN_CLOSE_WRITE | IN_ONESHOT);
+            if (watch_descriptor >= 0)
+            {
+                if (mi->inotify_watch != -1)
+                {
+                    hash_remove(m->inotify_watchers, (void *) (unsigned long)mi->inotify_watch);
+                }
+                hash_add(m->inotify_watchers, (const uintptr_t *)watch_descriptor, mi, true);
+                mi->inotify_watch = watch_descriptor;
+            }
+            else
+            {
+                msg(M_NONFATAL | M_ERRNO, "MULTI: inotify_add_watch error");
+            }
+        }
+#endif
+
+        if (!IS_SIG(&mi->context))
+        {
+            /* connection is "established" when SSL/TLS key negotiation succeeds
+             * and (if specified) auth user/pass succeeds */
+            if (!mi->connection_established_flag && CONNECTION_ESTABLISHED(&mi->context))
+            {
+                multi_connection_established(m, mi);
+            }
+
+            /* tell scheduler to wake us up at some point in the future */
+            multi_schedule_context_wakeup(m, mi);
+        }
+    }
+
+    if (IS_SIG(&mi->context))
+    {
+        if (flags & MPP_CLOSE_ON_SIGNAL)
+        {
+            multi_close_instance_on_signal(m, mi);
+            ret = false;
+        }
+    }
+    else
+    {
+        /* continue to pend on output? */
+        multi_set_pending(m, ANY_OUT(&mi->context) ? mi : NULL);
+
+#ifdef MULTI_DEBUG_EVENT_LOOP
+        printf("POST %s[%d] to=%d lo=%d/%d w=%d/%d\n",
+               id(mi),
+               (int) (mi == m->pending),
+               mi ? mi->context.c2.to_tun.len : -1,
+               mi ? mi->context.c2.to_link.len : -1,
+               (mi && mi->context.c2.fragment) ? mi->context.c2.fragment->outgoing.len : -1,
+               (int)mi->context.c2.timeval.tv_sec,
+               (int)mi->context.c2.timeval.tv_usec);
+#endif
+    }
+
+    if ((flags & MPP_RECORD_TOUCH) && m->mpp_touched)
+    {
+        *m->mpp_touched = mi;
+    }
+
+    return ret;
+}
+
+void
+multi_process_float(struct multi_context *m, struct multi_instance *mi)
+{
+    struct mroute_addr real;
+    struct hash *hash = m->hash;
+    struct gc_arena gc = gc_new();
+
+    if (!mroute_extract_openvpn_sockaddr(&real, &m->top.c2.from.dest, true))
+    {
+        goto done;
+    }
+
+    const uint32_t hv = hash_value(hash, &real);
+    struct hash_bucket *bucket = hash_bucket(hash, hv);
+
+    /* make sure that we don't float to an address taken by another client */
+    struct hash_element *he = hash_lookup_fast(hash, bucket, &real, hv);
+    if (he)
+    {
+        struct multi_instance *ex_mi = (struct multi_instance *) he->value;
+
+        struct tls_multi *m1 = mi->context.c2.tls_multi;
+        struct tls_multi *m2 = ex_mi->context.c2.tls_multi;
+
+        /* do not float if target address is taken by client with another cert */
+        if (!cert_hash_compare(m1->locked_cert_hash_set, m2->locked_cert_hash_set))
+        {
+            msg(D_MULTI_LOW, "Disallow float to an address taken by another client %s",
+                multi_instance_string(ex_mi, false, &gc));
+
+            mi->context.c2.buf.len = 0;
+
+            goto done;
+        }
+
+        msg(D_MULTI_MEDIUM, "closing instance %s", multi_instance_string(ex_mi, false, &gc));
+        multi_close_instance(m, ex_mi, false);
+    }
+
+    msg(D_MULTI_MEDIUM, "peer %" PRIu32 " (%s) floated from %s to %s",
+        mi->context.c2.tls_multi->peer_id,
+        tls_common_name(mi->context.c2.tls_multi, false),
+        mroute_addr_print(&mi->real, &gc),
+        print_link_socket_actual(&m->top.c2.from, &gc));
+
+    /* remove old address from hash table before changing address */
+    ASSERT(hash_remove(m->hash, &mi->real));
+    ASSERT(hash_remove(m->iter, &mi->real));
+
+    /* change external network address of the remote peer */
+    mi->real = real;
+    generate_prefix(mi);
+
+    mi->context.c2.from = m->top.c2.from;
+    mi->context.c2.to_link_addr = &mi->context.c2.from;
+
+    /* inherit parent link_socket and link_socket_info */
+    mi->context.c2.link_socket = m->top.c2.link_socket;
+    mi->context.c2.link_socket_info->lsa->actual = m->top.c2.from;
+
+    tls_update_remote_addr(mi->context.c2.tls_multi, &mi->context.c2.from);
+
+    ASSERT(hash_add(m->hash, &mi->real, mi, false));
+    ASSERT(hash_add(m->iter, &mi->real, mi, false));
+
+#ifdef MANAGEMENT_DEF_AUTH
+    ASSERT(hash_add(m->cid_hash, &mi->context.c2.mda_context.cid, mi, true));
+#endif
+
+done:
+    gc_free(&gc);
+}
+
+/*
+ * Process packets in the TCP/UDP socket -> TUN/TAP interface direction,
+ * i.e. client -> server direction.
+ */
+bool
+multi_process_incoming_link(struct multi_context *m, struct multi_instance *instance, const unsigned int mpp_flags)
+{
+    struct gc_arena gc = gc_new();
+
+    struct context *c;
+    struct mroute_addr src, dest;
+    unsigned int mroute_flags;
+    struct multi_instance *mi;
+    bool ret = true;
+    bool floated = false;
+
+    if (m->pending)
+    {
+        return true;
+    }
+
+    if (!instance)
+    {
+#ifdef MULTI_DEBUG_EVENT_LOOP
+        printf("TCP/UDP -> TUN [%d]\n", BLEN(&m->top.c2.buf));
+#endif
+        multi_set_pending(m, multi_get_create_instance_udp(m, &floated));
+    }
+    else
+    {
+        multi_set_pending(m, instance);
+    }
+
+    if (m->pending)
+    {
+        set_prefix(m->pending);
+
+        /* get instance context */
+        c = &m->pending->context;
+
+        if (!instance)
+        {
+            /* transfer packet pointer from top-level context buffer to instance */
+            c->c2.buf = m->top.c2.buf;
+
+            /* transfer from-addr from top-level context buffer to instance */
+            if (!floated)
+            {
+                c->c2.from = m->top.c2.from;
+            }
+        }
+
+        if (BLEN(&c->c2.buf) > 0)
+        {
+            struct link_socket_info *lsi;
+            const uint8_t *orig_buf;
+
+            /* decrypt in instance context */
+
+            perf_push(PERF_PROC_IN_LINK);
+            lsi = get_link_socket_info(c);
+            orig_buf = c->c2.buf.data;
+            if (process_incoming_link_part1(c, lsi, floated))
+            {
+                /* nonzero length means that we have a valid, decrypted packed */
+                if (floated && c->c2.buf.len > 0)
+                {
+                    multi_process_float(m, m->pending);
+                }
+
+                process_incoming_link_part2(c, lsi, orig_buf);
+            }
+            perf_pop();
+
+            if (TUNNEL_TYPE(m->top.c1.tuntap) == DEV_TYPE_TUN)
+            {
+                /* extract packet source and dest addresses */
+                mroute_flags = mroute_extract_addr_from_packet(&src,
+                                                               &dest,
+                                                               NULL,
+                                                               NULL,
+                                                               &c->c2.to_tun,
+                                                               DEV_TYPE_TUN);
+
+                /* drop packet if extract failed */
+                if (!(mroute_flags & MROUTE_EXTRACT_SUCCEEDED))
+                {
+                    c->c2.to_tun.len = 0;
+                }
+                /* make sure that source address is associated with this client */
+                else if (multi_get_instance_by_virtual_addr(m, &src, true) != m->pending)
+                {
+                    /* IPv6 link-local address (fe80::xxx)? */
+                    if ( (src.type & MR_ADDR_MASK) == MR_ADDR_IPV6
+                         && IN6_IS_ADDR_LINKLOCAL(&src.v6.addr) )
+                    {
+                        /* do nothing, for now.  TODO: add address learning */
+                    }
+                    else
+                    {
+                        msg(D_MULTI_DROPPED, "MULTI: bad source address from client [%s], packet dropped",
+                            mroute_addr_print(&src, &gc));
+                    }
+                    c->c2.to_tun.len = 0;
+                }
+                /* client-to-client communication enabled? */
+                else if (m->enable_c2c)
+                {
+                    /* multicast? */
+                    if (mroute_flags & MROUTE_EXTRACT_MCAST)
+                    {
+                        /* for now, treat multicast as broadcast */
+                        multi_bcast(m, &c->c2.to_tun, m->pending, NULL);
+                    }
+                    else /* possible client to client routing */
+                    {
+                        ASSERT(!(mroute_flags & MROUTE_EXTRACT_BCAST));
+                        mi = multi_get_instance_by_virtual_addr(m, &dest, true);
+
+                        /* if dest addr is a known client, route to it */
+                        if (mi)
+                        {
+#ifdef ENABLE_PF
+                            if (!pf_c2c_test(c, &mi->context, "tun_c2c"))
+                            {
+                                msg(D_PF_DROPPED, "PF: client -> client[%s] packet dropped by TUN packet filter",
+                                    mi_prefix(mi));
+                            }
+                            else
+#endif
+                            {
+                                multi_unicast(m, &c->c2.to_tun, mi);
+                                register_activity(c, BLEN(&c->c2.to_tun));
+                            }
+                            c->c2.to_tun.len = 0;
+                        }
+                    }
+                }
+#ifdef ENABLE_PF
+                if (c->c2.to_tun.len && !pf_addr_test(c, &dest, "tun_dest_addr"))
+                {
+                    msg(D_PF_DROPPED, "PF: client -> addr[%s] packet dropped by TUN packet filter",
+                        mroute_addr_print_ex(&dest, MAPF_SHOW_ARP, &gc));
+                    c->c2.to_tun.len = 0;
+                }
+#endif
+            }
+            else if (TUNNEL_TYPE(m->top.c1.tuntap) == DEV_TYPE_TAP)
+            {
+#ifdef ENABLE_PF
+                struct mroute_addr edest;
+                mroute_addr_reset(&edest);
+#endif
+                /* extract packet source and dest addresses */
+                mroute_flags = mroute_extract_addr_from_packet(&src,
+                                                               &dest,
+                                                               NULL,
+#ifdef ENABLE_PF
+                                                               &edest,
+#else
+                                                               NULL,
+#endif
+                                                               &c->c2.to_tun,
+                                                               DEV_TYPE_TAP);
+
+                if (mroute_flags & MROUTE_EXTRACT_SUCCEEDED)
+                {
+                    if (multi_learn_addr(m, m->pending, &src, 0) == m->pending)
+                    {
+                        /* check for broadcast */
+                        if (m->enable_c2c)
+                        {
+                            if (mroute_flags & (MROUTE_EXTRACT_BCAST|MROUTE_EXTRACT_MCAST))
+                            {
+                                multi_bcast(m, &c->c2.to_tun, m->pending, NULL);
+                            }
+                            else /* try client-to-client routing */
+                            {
+                                mi = multi_get_instance_by_virtual_addr(m, &dest, false);
+
+                                /* if dest addr is a known client, route to it */
+                                if (mi)
+                                {
+#ifdef ENABLE_PF
+                                    if (!pf_c2c_test(c, &mi->context, "tap_c2c"))
+                                    {
+                                        msg(D_PF_DROPPED, "PF: client -> client[%s] packet dropped by TAP packet filter",
+                                            mi_prefix(mi));
+                                    }
+                                    else
+#endif
+                                    {
+                                        multi_unicast(m, &c->c2.to_tun, mi);
+                                        register_activity(c, BLEN(&c->c2.to_tun));
+                                    }
+                                    c->c2.to_tun.len = 0;
+                                }
+                            }
+                        }
+#ifdef ENABLE_PF
+                        if (c->c2.to_tun.len && !pf_addr_test(c, &edest, "tap_dest_addr"))
+                        {
+                            msg(D_PF_DROPPED, "PF: client -> addr[%s] packet dropped by TAP packet filter",
+                                mroute_addr_print_ex(&edest, MAPF_SHOW_ARP, &gc));
+                            c->c2.to_tun.len = 0;
+                        }
+#endif
+                    }
+                    else
+                    {
+                        msg(D_MULTI_DROPPED, "MULTI: bad source address from client [%s], packet dropped",
+                            mroute_addr_print(&src, &gc));
+                        c->c2.to_tun.len = 0;
+                    }
+                }
+                else
+                {
+                    c->c2.to_tun.len = 0;
+                }
+            }
+        }
+
+        /* postprocess and set wakeup */
+        ret = multi_process_post(m, m->pending, mpp_flags);
+
+        clear_prefix();
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Process packets in the TUN/TAP interface -> TCP/UDP socket direction,
+ * i.e. server -> client direction.
+ */
+bool
+multi_process_incoming_tun(struct multi_context *m, const unsigned int mpp_flags)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = true;
+
+    if (BLEN(&m->top.c2.buf) > 0)
+    {
+        unsigned int mroute_flags;
+        struct mroute_addr src, dest;
+        const int dev_type = TUNNEL_TYPE(m->top.c1.tuntap);
+
+#ifdef ENABLE_PF
+        struct mroute_addr esrc, *e1, *e2;
+        if (dev_type == DEV_TYPE_TUN)
+        {
+            e1 = NULL;
+            e2 = &src;
+        }
+        else
+        {
+            e1 = e2 = &esrc;
+            mroute_addr_reset(&esrc);
+        }
+#endif
+
+#ifdef MULTI_DEBUG_EVENT_LOOP
+        printf("TUN -> TCP/UDP [%d]\n", BLEN(&m->top.c2.buf));
+#endif
+
+        if (m->pending)
+        {
+            return true;
+        }
+
+        /*
+         * Route an incoming tun/tap packet to
+         * the appropriate multi_instance object.
+         */
+
+        mroute_flags = mroute_extract_addr_from_packet(&src,
+                                                       &dest,
+#ifdef ENABLE_PF
+                                                       e1,
+#else
+                                                       NULL,
+#endif
+                                                       NULL,
+                                                       &m->top.c2.buf,
+                                                       dev_type);
+
+        if (mroute_flags & MROUTE_EXTRACT_SUCCEEDED)
+        {
+            struct context *c;
+
+            /* broadcast or multicast dest addr? */
+            if (mroute_flags & (MROUTE_EXTRACT_BCAST|MROUTE_EXTRACT_MCAST))
+            {
+                /* for now, treat multicast as broadcast */
+#ifdef ENABLE_PF
+                multi_bcast(m, &m->top.c2.buf, NULL, e2);
+#else
+                multi_bcast(m, &m->top.c2.buf, NULL, NULL);
+#endif
+            }
+            else
+            {
+                multi_set_pending(m, multi_get_instance_by_virtual_addr(m, &dest, dev_type == DEV_TYPE_TUN));
+
+                if (m->pending)
+                {
+                    /* get instance context */
+                    c = &m->pending->context;
+
+                    set_prefix(m->pending);
+
+#ifdef ENABLE_PF
+                    if (!pf_addr_test(c, e2, "tun_tap_src_addr"))
+                    {
+                        msg(D_PF_DROPPED, "PF: addr[%s] -> client packet dropped by packet filter",
+                            mroute_addr_print_ex(&src, MAPF_SHOW_ARP, &gc));
+                        buf_reset_len(&c->c2.buf);
+                    }
+                    else
+#endif
+                    {
+                        if (multi_output_queue_ready(m, m->pending))
+                        {
+                            /* transfer packet pointer from top-level context buffer to instance */
+                            c->c2.buf = m->top.c2.buf;
+                        }
+                        else
+                        {
+                            /* drop packet */
+                            msg(D_MULTI_DROPPED, "MULTI: packet dropped due to output saturation (multi_process_incoming_tun)");
+                            buf_reset_len(&c->c2.buf);
+                        }
+                    }
+
+                    /* encrypt in instance context */
+                    process_incoming_tun(c);
+
+                    /* postprocess and set wakeup */
+                    ret = multi_process_post(m, m->pending, mpp_flags);
+
+                    clear_prefix();
+                }
+            }
+        }
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Process a possible client-to-client/bcast/mcast message in the
+ * queue.
+ */
+struct multi_instance *
+multi_get_queue(struct mbuf_set *ms)
+{
+    struct mbuf_item item;
+
+    if (mbuf_extract_item(ms, &item)) /* cleartext IP packet */
+    {
+        unsigned int pip_flags = PIPV4_PASSTOS;
+
+        set_prefix(item.instance);
+        item.instance->context.c2.buf = item.buffer->buf;
+        if (item.buffer->flags & MF_UNICAST) /* --mssfix doesn't make sense for broadcast or multicast */
+        {
+            pip_flags |= PIP_MSSFIX;
+        }
+        process_ip_header(&item.instance->context, pip_flags, &item.instance->context.c2.buf);
+        encrypt_sign(&item.instance->context, true);
+        mbuf_free_buf(item.buffer);
+
+        dmsg(D_MULTI_DEBUG, "MULTI: C2C/MCAST/BCAST");
+
+        clear_prefix();
+        return item.instance;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+/*
+ * Called when an I/O wait times out.  Usually means that a particular
+ * client instance object needs timer-based service.
+ */
+bool
+multi_process_timeout(struct multi_context *m, const unsigned int mpp_flags)
+{
+    bool ret = true;
+
+#ifdef MULTI_DEBUG_EVENT_LOOP
+    printf("%s -> TIMEOUT\n", id(m->earliest_wakeup));
+#endif
+
+    /* instance marked for wakeup? */
+    if (m->earliest_wakeup)
+    {
+        if (m->earliest_wakeup == (struct multi_instance *)&m->deferred_shutdown_signal)
+        {
+            schedule_remove_entry(m->schedule, (struct schedule_entry *) &m->deferred_shutdown_signal);
+            throw_signal(m->deferred_shutdown_signal.signal_received);
+        }
+        else
+        {
+            set_prefix(m->earliest_wakeup);
+            ret = multi_process_post(m, m->earliest_wakeup, mpp_flags);
+            clear_prefix();
+        }
+        m->earliest_wakeup = NULL;
+    }
+    return ret;
+}
+
+/*
+ * Drop a TUN/TAP outgoing packet..
+ */
+void
+multi_process_drop_outgoing_tun(struct multi_context *m, const unsigned int mpp_flags)
+{
+    struct multi_instance *mi = m->pending;
+
+    ASSERT(mi);
+
+    set_prefix(mi);
+
+    msg(D_MULTI_ERRORS, "MULTI: Outgoing TUN queue full, dropped packet len=%d",
+        mi->context.c2.to_tun.len);
+
+    buf_reset(&mi->context.c2.to_tun);
+
+    multi_process_post(m, mi, mpp_flags);
+    clear_prefix();
+}
+
+/*
+ * Per-client route quota management
+ */
+
+void
+route_quota_exceeded(const struct multi_instance *mi)
+{
+    struct gc_arena gc = gc_new();
+    msg(D_ROUTE_QUOTA, "MULTI ROUTE: route quota (%d) exceeded for %s (see --max-routes-per-client option)",
+        mi->context.options.max_routes_per_client,
+        multi_instance_string(mi, false, &gc));
+    gc_free(&gc);
+}
+
+#ifdef ENABLE_DEBUG
+/*
+ * Flood clients with random packets
+ */
+static void
+gremlin_flood_clients(struct multi_context *m)
+{
+    const int level = GREMLIN_PACKET_FLOOD_LEVEL(m->top.options.gremlin);
+    if (level)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer buf = alloc_buf_gc(BUF_SIZE(&m->top.c2.frame), &gc);
+        struct packet_flood_parms parm = get_packet_flood_parms(level);
+        int i;
+
+        ASSERT(buf_init(&buf, FRAME_HEADROOM(&m->top.c2.frame)));
+        parm.packet_size = min_int(parm.packet_size, MAX_RW_SIZE_TUN(&m->top.c2.frame));
+
+        msg(D_GREMLIN, "GREMLIN_FLOOD_CLIENTS: flooding clients with %d packets of size %d",
+            parm.n_packets,
+            parm.packet_size);
+
+        for (i = 0; i < parm.packet_size; ++i)
+        {
+            ASSERT(buf_write_u8(&buf, get_random() & 0xFF));
+        }
+
+        for (i = 0; i < parm.n_packets; ++i)
+        {
+            multi_bcast(m, &buf, NULL, NULL);
+        }
+
+        gc_free(&gc);
+    }
+}
+#endif /* ifdef ENABLE_DEBUG */
+
+static bool
+stale_route_check_trigger(struct multi_context *m)
+{
+    struct timeval null;
+    CLEAR(null);
+    return event_timeout_trigger(&m->stale_routes_check_et, &null, ETT_DEFAULT);
+}
+
+/*
+ * Process timers in the top-level context
+ */
+void
+multi_process_per_second_timers_dowork(struct multi_context *m)
+{
+    /* possibly reap instances/routes in vhash */
+    multi_reap_process(m);
+
+    /* possibly print to status log */
+    if (m->top.c1.status_output)
+    {
+        if (status_trigger(m->top.c1.status_output))
+        {
+            multi_print_status(m, m->top.c1.status_output, m->status_file_version);
+        }
+    }
+
+    /* possibly flush ifconfig-pool file */
+    multi_ifconfig_pool_persist(m, false);
+
+#ifdef ENABLE_DEBUG
+    gremlin_flood_clients(m);
+#endif
+
+    /* Should we check for stale routes? */
+    if (m->top.options.stale_routes_check_interval && stale_route_check_trigger(m))
+    {
+        check_stale_routes(m);
+    }
+}
+
+void
+multi_top_init(struct multi_context *m, const struct context *top)
+{
+    inherit_context_top(&m->top, top);
+    m->top.c2.buffers = init_context_buffers(&top->c2.frame);
+}
+
+void
+multi_top_free(struct multi_context *m)
+{
+    close_context(&m->top, -1, CC_GC_FREE);
+    free_context_buffers(m->top.c2.buffers);
+}
+
+static bool
+is_exit_restart(int sig)
+{
+    return (sig == SIGUSR1 || sig == SIGTERM || sig == SIGHUP || sig == SIGINT);
+}
+
+static void
+multi_push_restart_schedule_exit(struct multi_context *m, bool next_server)
+{
+    struct hash_iterator hi;
+    struct hash_element *he;
+    struct timeval tv;
+
+    /* tell all clients to restart */
+    hash_iterator_init(m->iter, &hi);
+    while ((he = hash_iterator_next(&hi)))
+    {
+        struct multi_instance *mi = (struct multi_instance *) he->value;
+        if (!mi->halt)
+        {
+            send_control_channel_string(&mi->context, next_server ? "RESTART,[N]" : "RESTART", D_PUSH);
+            multi_schedule_context_wakeup(m, mi);
+        }
+    }
+    hash_iterator_free(&hi);
+
+    /* reschedule signal */
+    ASSERT(!openvpn_gettimeofday(&m->deferred_shutdown_signal.wakeup, NULL));
+    tv.tv_sec = 2;
+    tv.tv_usec = 0;
+    tv_add(&m->deferred_shutdown_signal.wakeup, &tv);
+
+    m->deferred_shutdown_signal.signal_received = m->top.sig->signal_received;
+
+    schedule_add_entry(m->schedule,
+                       (struct schedule_entry *) &m->deferred_shutdown_signal,
+                       &m->deferred_shutdown_signal.wakeup,
+                       compute_wakeup_sigma(&m->deferred_shutdown_signal.wakeup));
+
+    m->top.sig->signal_received = 0;
+}
+
+/*
+ * Return true if event loop should break,
+ * false if it should continue.
+ */
+bool
+multi_process_signal(struct multi_context *m)
+{
+    if (m->top.sig->signal_received == SIGUSR2)
+    {
+        struct status_output *so = status_open(NULL, 0, M_INFO, NULL, 0);
+        multi_print_status(m, so, m->status_file_version);
+        status_close(so);
+        m->top.sig->signal_received = 0;
+        return false;
+    }
+    else if (proto_is_dgram(m->top.options.ce.proto)
+             && is_exit_restart(m->top.sig->signal_received)
+             && (m->deferred_shutdown_signal.signal_received == 0)
+             && m->top.options.ce.explicit_exit_notification != 0)
+    {
+        multi_push_restart_schedule_exit(m, m->top.options.ce.explicit_exit_notification == 2);
+        return false;
+    }
+    return true;
+}
+
+/*
+ * Called when an instance should be closed due to the
+ * reception of a soft signal.
+ */
+void
+multi_close_instance_on_signal(struct multi_context *m, struct multi_instance *mi)
+{
+    remap_signal(&mi->context);
+    set_prefix(mi);
+    print_signal(mi->context.sig, "client-instance", D_MULTI_LOW);
+    clear_prefix();
+    multi_close_instance(m, mi, false);
+}
+
+static void
+multi_signal_instance(struct multi_context *m, struct multi_instance *mi, const int sig)
+{
+    mi->context.sig->signal_received = sig;
+    multi_close_instance_on_signal(m, mi);
+}
+
+/*
+ * Management subsystem callbacks
+ */
+
+#ifdef ENABLE_MANAGEMENT
+
+static void
+management_callback_status(void *arg, const int version, struct status_output *so)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+
+    if (!version)
+    {
+        multi_print_status(m, so, m->status_file_version);
+    }
+    else
+    {
+        multi_print_status(m, so, version);
+    }
+}
+
+static int
+management_callback_n_clients(void *arg)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    return m->n_clients;
+}
+
+static int
+management_callback_kill_by_cn(void *arg, const char *del_cn)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct hash_iterator hi;
+    struct hash_element *he;
+    int count = 0;
+
+    hash_iterator_init(m->iter, &hi);
+    while ((he = hash_iterator_next(&hi)))
+    {
+        struct multi_instance *mi = (struct multi_instance *) he->value;
+        if (!mi->halt)
+        {
+            const char *cn = tls_common_name(mi->context.c2.tls_multi, false);
+            if (cn && !strcmp(cn, del_cn))
+            {
+                multi_signal_instance(m, mi, SIGTERM);
+                ++count;
+            }
+        }
+    }
+    hash_iterator_free(&hi);
+    return count;
+}
+
+static int
+management_callback_kill_by_addr(void *arg, const in_addr_t addr, const int port)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct hash_iterator hi;
+    struct hash_element *he;
+    struct openvpn_sockaddr saddr;
+    struct mroute_addr maddr;
+    int count = 0;
+
+    CLEAR(saddr);
+    saddr.addr.in4.sin_family = AF_INET;
+    saddr.addr.in4.sin_addr.s_addr = htonl(addr);
+    saddr.addr.in4.sin_port = htons(port);
+    if (mroute_extract_openvpn_sockaddr(&maddr, &saddr, true))
+    {
+        hash_iterator_init(m->iter, &hi);
+        while ((he = hash_iterator_next(&hi)))
+        {
+            struct multi_instance *mi = (struct multi_instance *) he->value;
+            if (!mi->halt && mroute_addr_equal(&maddr, &mi->real))
+            {
+                multi_signal_instance(m, mi, SIGTERM);
+                ++count;
+            }
+        }
+        hash_iterator_free(&hi);
+    }
+    return count;
+}
+
+static void
+management_delete_event(void *arg, event_t event)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    if (m->mtcp)
+    {
+        multi_tcp_delete_event(m->mtcp, event);
+    }
+}
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+#ifdef MANAGEMENT_DEF_AUTH
+
+static struct multi_instance *
+lookup_by_cid(struct multi_context *m, const unsigned long cid)
+{
+    if (m)
+    {
+        struct multi_instance *mi = (struct multi_instance *) hash_lookup(m->cid_hash, &cid);
+        if (mi && !mi->halt)
+        {
+            return mi;
+        }
+    }
+    return NULL;
+}
+
+static bool
+management_kill_by_cid(void *arg, const unsigned long cid, const char *kill_msg)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct multi_instance *mi = lookup_by_cid(m, cid);
+    if (mi)
+    {
+        send_restart(&mi->context, kill_msg); /* was: multi_signal_instance (m, mi, SIGTERM); */
+        multi_schedule_context_wakeup(m, mi);
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static bool
+management_client_auth(void *arg,
+                       const unsigned long cid,
+                       const unsigned int mda_key_id,
+                       const bool auth,
+                       const char *reason,
+                       const char *client_reason,
+                       struct buffer_list *cc_config)  /* ownership transferred */
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct multi_instance *mi = lookup_by_cid(m, cid);
+    bool cc_config_owned = true;
+    bool ret = false;
+
+    if (mi)
+    {
+        ret = tls_authenticate_key(mi->context.c2.tls_multi, mda_key_id, auth, client_reason);
+        if (ret)
+        {
+            if (auth)
+            {
+                if (!mi->connection_established_flag)
+                {
+                    set_cc_config(mi, cc_config);
+                    cc_config_owned = false;
+                }
+            }
+            else
+            {
+                if (reason)
+                {
+                    msg(D_MULTI_LOW, "MULTI: connection rejected: %s, CLI:%s", reason, np(client_reason));
+                }
+                if (mi->connection_established_flag)
+                {
+                    send_auth_failed(&mi->context, client_reason); /* mid-session reauth failed */
+                    multi_schedule_context_wakeup(m, mi);
+                }
+            }
+        }
+    }
+    if (cc_config_owned && cc_config)
+    {
+        buffer_list_free(cc_config);
+    }
+    return ret;
+}
+
+static char *
+management_get_peer_info(void *arg, const unsigned long cid)
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct multi_instance *mi = lookup_by_cid(m, cid);
+    char *ret = NULL;
+
+    if (mi)
+    {
+        ret = tls_get_peer_info(mi->context.c2.tls_multi);
+    }
+
+    return ret;
+}
+
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+
+#ifdef MANAGEMENT_PF
+static bool
+management_client_pf(void *arg,
+                     const unsigned long cid,
+                     struct buffer_list *pf_config)  /* ownership transferred */
+{
+    struct multi_context *m = (struct multi_context *) arg;
+    struct multi_instance *mi = lookup_by_cid(m, cid);
+    bool ret = false;
+
+    if (mi && pf_config)
+    {
+        ret = pf_load_from_buffer_list(&mi->context, pf_config);
+    }
+
+    if (pf_config)
+    {
+        buffer_list_free(pf_config);
+    }
+    return ret;
+}
+#endif /* ifdef MANAGEMENT_PF */
+
+void
+init_management_callback_multi(struct multi_context *m)
+{
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        struct management_callback cb;
+        CLEAR(cb);
+        cb.arg = m;
+        cb.flags = MCF_SERVER;
+        cb.status = management_callback_status;
+        cb.show_net = management_show_net_callback;
+        cb.kill_by_cn = management_callback_kill_by_cn;
+        cb.kill_by_addr = management_callback_kill_by_addr;
+        cb.delete_event = management_delete_event;
+        cb.n_clients = management_callback_n_clients;
+#ifdef MANAGEMENT_DEF_AUTH
+        cb.kill_by_cid = management_kill_by_cid;
+        cb.client_auth = management_client_auth;
+        cb.get_peer_info = management_get_peer_info;
+#endif
+#ifdef MANAGEMENT_PF
+        cb.client_pf = management_client_pf;
+#endif
+        management_set_callback(management, &cb);
+    }
+#endif /* ifdef ENABLE_MANAGEMENT */
+}
+
+/*
+ * Top level event loop.
+ */
+void
+tunnel_server(struct context *top)
+{
+    ASSERT(top->options.mode == MODE_SERVER);
+
+    if (proto_is_dgram(top->options.ce.proto))
+    {
+        tunnel_server_udp(top);
+    }
+    else
+    {
+        tunnel_server_tcp(top);
+    }
+}
+
+#else  /* if P2MP_SERVER */
+static void
+dummy(void)
+{
+}
+#endif /* P2MP_SERVER */
diff --git a/src/openvpn/multi.h b/src/openvpn/multi.h
new file mode 100644
index 0000000..ebcc22d
--- /dev/null
+++ b/src/openvpn/multi.h
@@ -0,0 +1,654 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Header file for server-mode related structures and functions.
+ */
+
+#ifndef MULTI_H
+#define MULTI_H
+
+#if P2MP_SERVER
+
+#include "init.h"
+#include "forward.h"
+#include "mroute.h"
+#include "mbuf.h"
+#include "list.h"
+#include "schedule.h"
+#include "pool.h"
+#include "mudp.h"
+#include "mtcp.h"
+#include "perf.h"
+
+#define MULTI_PREFIX_MAX_LENGTH 256
+
+/*
+ * Walk (don't run) through the routing table,
+ * deleting old entries, and possibly multi_instance
+ * structs as well which have been marked for deletion.
+ */
+struct multi_reap
+{
+    int bucket_base;
+    int buckets_per_pass;
+    time_t last_call;
+};
+
+
+struct deferred_signal_schedule_entry
+{
+    struct schedule_entry se;
+    int signal_received;
+    struct timeval wakeup;
+};
+
+/**
+ * Server-mode state structure for one single VPN tunnel.
+ *
+ * This structure is used by OpenVPN processes running in server-mode to
+ * store state information related to one single VPN tunnel.
+ *
+ * The @ref tunnel_state "Structure of VPN tunnel state storage" related
+ * page describes the role the structure plays when OpenVPN is running in
+ * server-mode.
+ */
+struct multi_instance {
+    struct schedule_entry se;  /* this must be the first element of the structure */
+    struct gc_arena gc;
+    bool defined;
+    bool halt;
+    int refcount;
+    int route_count;           /* number of routes (including cached routes) owned by this instance */
+    time_t created;             /**< Time at which a VPN tunnel instance
+                                 *   was created.  This parameter is set
+                                 *   by the \c multi_create_instance()
+                                 *   function. */
+    struct timeval wakeup;     /* absolute time */
+    struct mroute_addr real;    /**< External network address of the
+                                 *   remote peer. */
+    ifconfig_pool_handle vaddr_handle;
+    char msg_prefix[MULTI_PREFIX_MAX_LENGTH];
+
+    /* queued outgoing data in Server/TCP mode */
+    unsigned int tcp_rwflags;
+    struct mbuf_set *tcp_link_out_deferred;
+    bool socket_set_called;
+
+    in_addr_t reporting_addr;     /* IP address shown in status listing */
+    struct in6_addr reporting_addr_ipv6; /* IPv6 address in status listing */
+
+    bool did_open_context;
+    bool did_real_hash;
+    bool did_iter;
+#ifdef MANAGEMENT_DEF_AUTH
+    bool did_cid_hash;
+    struct buffer_list *cc_config;
+#endif
+    bool connection_established_flag;
+    bool did_iroutes;
+    int n_clients_delta; /* added to multi_context.n_clients when instance is closed */
+
+    struct context context;     /**< The context structure storing state
+                                 *   for this VPN tunnel. */
+
+#ifdef ENABLE_ASYNC_PUSH
+    int inotify_watch; /* watch descriptor for acf */
+#endif
+};
+
+
+/**
+ * Main OpenVPN server state structure.
+ *
+ * This structure is used by OpenVPN processes running in server-mode to
+ * store all the VPN tunnel and process-wide state.
+ *
+ * The @ref tunnel_state "Structure of VPN tunnel state storage" related
+ * page describes the role the structure plays when OpenVPN is running in
+ * server-mode.
+ */
+struct multi_context {
+#define MC_UNDEF                      0
+#define MC_SINGLE_THREADED            (1<<0)
+#define MC_MULTI_THREADED_MASTER      (1<<1)
+#define MC_MULTI_THREADED_WORKER      (1<<2)
+#define MC_MULTI_THREADED_SCHEDULER   (1<<3)
+#define MC_WORK_THREAD                (MC_MULTI_THREADED_WORKER|MC_MULTI_THREADED_SCHEDULER)
+    int thread_mode;
+
+    struct multi_instance **instances;  /**< Array of multi_instances. An instance can be
+                                         * accessed using peer-id as an index. */
+
+    struct hash *hash;          /**< VPN tunnel instances indexed by real
+                                 *   address of the remote peer. */
+    struct hash *vhash;         /**< VPN tunnel instances indexed by
+                                 *   virtual address of remote hosts. */
+    struct hash *iter;          /**< VPN tunnel instances indexed by real
+                                 *   address of the remote peer, optimized
+                                 *   for iteration. */
+    struct schedule *schedule;
+    struct mbuf_set *mbuf;      /**< Set of buffers for passing data
+                                 *   channel packets between VPN tunnel
+                                 *   instances. */
+    struct multi_tcp *mtcp;     /**< State specific to OpenVPN using TCP
+                                 *   as external transport. */
+    struct ifconfig_pool *ifconfig_pool;
+    struct frequency_limit *new_connection_limiter;
+    struct mroute_helper *route_helper;
+    struct multi_reap *reaper;
+    struct mroute_addr local;
+    bool enable_c2c;
+    int max_clients;
+    int tcp_queue_limit;
+    int status_file_version;
+    int n_clients; /* current number of authenticated clients */
+
+#ifdef MANAGEMENT_DEF_AUTH
+    struct hash *cid_hash;
+    unsigned long cid_counter;
+#endif
+
+    struct multi_instance *pending;
+    struct multi_instance *earliest_wakeup;
+    struct multi_instance **mpp_touched;
+    struct context_buffers *context_buffers;
+    time_t per_second_trigger;
+
+    struct context top;         /**< Storage structure for process-wide
+                                 *   configuration. */
+
+    /*
+     * Timer object for stale route check
+     */
+    struct event_timeout stale_routes_check_et;
+
+#ifdef ENABLE_ASYNC_PUSH
+    /* mapping between inotify watch descriptors and multi_instances */
+    struct hash *inotify_watchers;
+#endif
+
+    struct deferred_signal_schedule_entry deferred_shutdown_signal;
+};
+
+/*
+ * Host route
+ */
+struct multi_route
+{
+    struct mroute_addr addr;
+    struct multi_instance *instance;
+
+#define MULTI_ROUTE_CACHE   (1<<0)
+#define MULTI_ROUTE_AGEABLE (1<<1)
+    unsigned int flags;
+
+    unsigned int cache_generation;
+    time_t last_reference;
+};
+
+
+/**************************************************************************/
+/**
+ * Main event loop for OpenVPN in server mode.
+ * @ingroup eventloop
+ *
+ * This function calls the appropriate main event loop function depending
+ * on the transport protocol used:
+ *  - \c tunnel_server_udp()
+ *  - \c tunnel_server_tcp()
+ *
+ * @param top          - Top-level context structure.
+ */
+void tunnel_server(struct context *top);
+
+
+const char *multi_instance_string(const struct multi_instance *mi, bool null, struct gc_arena *gc);
+
+/*
+ * Called by mtcp.c, mudp.c, or other (to be written) protocol drivers
+ */
+
+void multi_init(struct multi_context *m, struct context *t, bool tcp_mode, int thread_mode);
+
+void multi_uninit(struct multi_context *m);
+
+void multi_top_init(struct multi_context *m, const struct context *top);
+
+void multi_top_free(struct multi_context *m);
+
+struct multi_instance *multi_create_instance(struct multi_context *m, const struct mroute_addr *real);
+
+void multi_close_instance(struct multi_context *m, struct multi_instance *mi, bool shutdown);
+
+bool multi_process_timeout(struct multi_context *m, const unsigned int mpp_flags);
+
+/**
+ * Handles peer floating.
+ *
+ * If peer is floated to a taken address, either drops packet
+ * (if peer that owns address has different CN) or disconnects
+ * existing peer. Updates multi_instance with new address,
+ * updates hashtables in multi_context.
+ */
+void multi_process_float(struct multi_context *m, struct multi_instance *mi);
+
+#define MPP_PRE_SELECT             (1<<0)
+#define MPP_CONDITIONAL_PRE_SELECT (1<<1)
+#define MPP_CLOSE_ON_SIGNAL        (1<<2)
+#define MPP_RECORD_TOUCH           (1<<3)
+
+
+/**************************************************************************/
+/**
+ * Perform postprocessing of a VPN tunnel instance.
+ *
+ * After some VPN tunnel activity has taken place, the VPN tunnel's state
+ * may need updating and some follow-up action may be required.  This
+ * function controls the necessary postprocessing.  It is called by many
+ * other functions that handle VPN tunnel related activity, such as \c
+ * multi_process_incoming_link(), \c multi_process_outgoing_link(), \c
+ * multi_process_incoming_tun(), \c multi_process_outgoing_tun(), and \c
+ * multi_process_timeout(), among others.
+ *
+ * @param m            - The single \c multi_context structure.
+ * @param mi           - The \c multi_instance of the VPN tunnel to be
+ *                       postprocessed.
+ * @param flags        - Fast I/O optimization flags.
+ *
+ * @return
+ *  - True, if the VPN tunnel instance \a mi was not closed due to a
+ *    signal during processing.
+ *  - False, if the VPN tunnel instance \a mi was closed.
+ */
+bool multi_process_post(struct multi_context *m, struct multi_instance *mi, const unsigned int flags);
+
+
+/**************************************************************************/
+/**
+ * Demultiplex and process a packet received over the external network
+ * interface.
+ * @ingroup external_multiplexer
+ *
+ * This function determines which VPN tunnel instance the incoming packet
+ * is associated with, and then calls \c process_incoming_link() to handle
+ * it.  Afterwards, if the packet is destined for a broadcast/multicast
+ * address or a remote host reachable through a different VPN tunnel, this
+ * function takes care of sending it they are.
+ *
+ * @note This function is only used by OpenVPN processes which are running
+ *     in server mode, and can therefore sustain multiple active VPN
+ *     tunnels.
+ *
+ * @param m            - The single \c multi_context structure.
+ * @param instance     - The VPN tunnel state structure associated with
+ *                       the incoming packet, if known, as is the case
+ *                       when using TCP transport. Otherwise NULL, as is
+ *                       the case when using UDP transport.
+ * @param mpp_flags    - Fast I/O optimization flags.
+ */
+bool multi_process_incoming_link(struct multi_context *m, struct multi_instance *instance, const unsigned int mpp_flags);
+
+
+/**
+ * Determine the destination VPN tunnel of a packet received over the
+ * virtual tun/tap network interface and then process it accordingly.
+ * @ingroup internal_multiplexer
+ *
+ * This function determines which VPN tunnel instance the packet is
+ * destined for, and then calls \c process_outgoing_tun() to handle it.
+ *
+ * @note This function is only used by OpenVPN processes which are running
+ *     in server mode, and can therefore sustain multiple active VPN
+ *     tunnels.
+ *
+ * @param m            - The single \c multi_context structure.
+ * @param mpp_flags    - Fast I/O optimization flags.
+ */
+bool multi_process_incoming_tun(struct multi_context *m, const unsigned int mpp_flags);
+
+
+void multi_process_drop_outgoing_tun(struct multi_context *m, const unsigned int mpp_flags);
+
+void multi_print_status(struct multi_context *m, struct status_output *so, const int version);
+
+struct multi_instance *multi_get_queue(struct mbuf_set *ms);
+
+void multi_add_mbuf(struct multi_context *m,
+                    struct multi_instance *mi,
+                    struct mbuf_buffer *mb);
+
+void multi_ifconfig_pool_persist(struct multi_context *m, bool force);
+
+bool multi_process_signal(struct multi_context *m);
+
+void multi_close_instance_on_signal(struct multi_context *m, struct multi_instance *mi);
+
+void init_management_callback_multi(struct multi_context *m);
+
+#ifdef ENABLE_ASYNC_PUSH
+/**
+ * Called when inotify event is fired, which happens when acf file is closed or deleted.
+ * Continues authentication and sends push_repl
+ *
+ * @param m multi_context
+ * @param mpp_flags
+ */
+void multi_process_file_closed(struct multi_context *m, const unsigned int mpp_flags);
+
+#endif
+
+/*
+ * Return true if our output queue is not full
+ */
+static inline bool
+multi_output_queue_ready(const struct multi_context *m,
+                         const struct multi_instance *mi)
+{
+    if (mi->tcp_link_out_deferred)
+    {
+        return mbuf_len(mi->tcp_link_out_deferred) <= m->tcp_queue_limit;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Determine which instance has pending output
+ * and prepare the output for sending in
+ * the to_link buffer.
+ */
+static inline struct multi_instance *
+multi_process_outgoing_link_pre(struct multi_context *m)
+{
+    struct multi_instance *mi = NULL;
+
+    if (m->pending)
+    {
+        mi = m->pending;
+    }
+    else if (mbuf_defined(m->mbuf))
+    {
+        mi = multi_get_queue(m->mbuf);
+    }
+    return mi;
+}
+
+/*
+ * Per-client route quota management
+ */
+
+void route_quota_exceeded(const struct multi_instance *mi);
+
+static inline void
+route_quota_inc(struct multi_instance *mi)
+{
+    ++mi->route_count;
+}
+
+static inline void
+route_quota_dec(struct multi_instance *mi)
+{
+    --mi->route_count;
+}
+
+/* can we add a new route? */
+static inline bool
+route_quota_test(const struct multi_instance *mi)
+{
+    if (mi->route_count >= mi->context.options.max_routes_per_client)
+    {
+        route_quota_exceeded(mi);
+        return false;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Instance reference counting
+ */
+
+static inline void
+multi_instance_inc_refcount(struct multi_instance *mi)
+{
+    ++mi->refcount;
+}
+
+static inline void
+multi_instance_dec_refcount(struct multi_instance *mi)
+{
+    if (--mi->refcount <= 0)
+    {
+        gc_free(&mi->gc);
+        free(mi);
+    }
+}
+
+static inline void
+multi_route_del(struct multi_route *route)
+{
+    struct multi_instance *mi = route->instance;
+    route_quota_dec(mi);
+    multi_instance_dec_refcount(mi);
+    free(route);
+}
+
+static inline bool
+multi_route_defined(const struct multi_context *m,
+                    const struct multi_route *r)
+{
+    if (r->instance->halt)
+    {
+        return false;
+    }
+    else if ((r->flags & MULTI_ROUTE_CACHE)
+             && r->cache_generation != m->route_helper->cache_generation)
+    {
+        return false;
+    }
+    else if ((r->flags & MULTI_ROUTE_AGEABLE)
+             && r->last_reference + m->route_helper->ageable_ttl_secs < now)
+    {
+        return false;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Takes prefix away from multi_instance.
+ */
+void
+ungenerate_prefix(struct multi_instance *mi);
+
+/*
+ * Set a msg() function prefix with our current client instance ID.
+ */
+
+static inline void
+set_prefix(struct multi_instance *mi)
+{
+#ifdef MULTI_DEBUG_EVENT_LOOP
+    if (mi->msg_prefix[0])
+    {
+        printf("[%s]\n", mi->msg_prefix);
+    }
+#endif
+    msg_set_prefix(mi->msg_prefix[0] ? mi->msg_prefix : NULL);
+}
+
+static inline void
+clear_prefix(void)
+{
+#ifdef MULTI_DEBUG_EVENT_LOOP
+    printf("[NULL]\n");
+#endif
+    msg_set_prefix(NULL);
+}
+
+/*
+ * Instance Reaper
+ *
+ * Reaper constants.  The reaper is the process where the virtual address
+ * and virtual route hash table is scanned for dead entries which are
+ * then removed.  The hash table could potentially be quite large, so we
+ * don't want to reap in a single pass.
+ */
+
+#define REAP_MAX_WAKEUP   10  /* Do reap pass at least once per n seconds */
+#define REAP_DIVISOR     256  /* How many passes to cover whole hash table */
+#define REAP_MIN          16  /* Minimum number of buckets per pass */
+#define REAP_MAX        1024  /* Maximum number of buckets per pass */
+
+/*
+ * Mark a cached host route for deletion after this
+ * many seconds without any references.
+ */
+#define MULTI_CACHE_ROUTE_TTL 60
+
+static inline void
+multi_reap_process(const struct multi_context *m)
+{
+    void multi_reap_process_dowork(const struct multi_context *m);
+
+    if (m->reaper->last_call != now)
+    {
+        multi_reap_process_dowork(m);
+    }
+}
+
+static inline void
+multi_process_per_second_timers(struct multi_context *m)
+{
+    if (m->per_second_trigger != now)
+    {
+        void multi_process_per_second_timers_dowork(struct multi_context *m);
+
+        multi_process_per_second_timers_dowork(m);
+        m->per_second_trigger = now;
+    }
+}
+
+/*
+ * Compute earliest timeout expiry from the set of
+ * all instances.  Output:
+ *
+ * m->earliest_wakeup : instance needing the earliest service.
+ * dest               : earliest timeout as a delta in relation
+ *                      to current time.
+ */
+static inline void
+multi_get_timeout(struct multi_context *m, struct timeval *dest)
+{
+    struct timeval tv, current;
+
+    CLEAR(tv);
+    m->earliest_wakeup = (struct multi_instance *) schedule_get_earliest_wakeup(m->schedule, &tv);
+    if (m->earliest_wakeup)
+    {
+        ASSERT(!openvpn_gettimeofday(&current, NULL));
+        tv_delta(dest, &current, &tv);
+        if (dest->tv_sec >= REAP_MAX_WAKEUP)
+        {
+            m->earliest_wakeup = NULL;
+            dest->tv_sec = REAP_MAX_WAKEUP;
+            dest->tv_usec = 0;
+        }
+    }
+    else
+    {
+        dest->tv_sec = REAP_MAX_WAKEUP;
+        dest->tv_usec = 0;
+    }
+}
+
+
+/**
+ * Send a packet over the virtual tun/tap network interface to its locally
+ * reachable destination.
+ * @ingroup internal_multiplexer
+ *
+ * This function calls \c process_outgoing_tun() to perform the actual
+ * sending of the packet.  Afterwards, it calls \c multi_process_post() to
+ * perform server-mode postprocessing.
+ *
+ * @param m            - The single \c multi_context structure.
+ * @param mpp_flags    - Fast I/O optimization flags.
+ *
+ * @return
+ *  - True, if the \c multi_instance associated with the packet sent was
+ *    not closed due to a signal during processing.
+ *  - Falls, if the \c multi_instance was closed.
+ */
+static inline bool
+multi_process_outgoing_tun(struct multi_context *m, const unsigned int mpp_flags)
+{
+    struct multi_instance *mi = m->pending;
+    bool ret = true;
+
+    ASSERT(mi);
+#ifdef MULTI_DEBUG_EVENT_LOOP
+    printf("%s -> TUN len=%d\n",
+           id(mi),
+           mi->context.c2.to_tun.len);
+#endif
+    set_prefix(mi);
+    process_outgoing_tun(&mi->context);
+    ret = multi_process_post(m, mi, mpp_flags);
+    clear_prefix();
+    return ret;
+}
+
+
+
+static inline bool
+multi_process_outgoing_link_dowork(struct multi_context *m, struct multi_instance *mi, const unsigned int mpp_flags)
+{
+    bool ret = true;
+    set_prefix(mi);
+    process_outgoing_link(&mi->context);
+    ret = multi_process_post(m, mi, mpp_flags);
+    clear_prefix();
+    return ret;
+}
+
+/*
+ * Check for signals.
+ */
+#define MULTI_CHECK_SIG(m) EVENT_LOOP_CHECK_SIGNAL(&(m)->top, multi_process_signal, (m))
+
+static inline void
+multi_set_pending(struct multi_context *m, struct multi_instance *mi)
+{
+    m->pending = mi;
+}
+
+#endif /* P2MP_SERVER */
+#endif /* MULTI_H */
diff --git a/src/openvpn/ntlm.c b/src/openvpn/ntlm.c
new file mode 100644
index 0000000..077fa3e
--- /dev/null
+++ b/src/openvpn/ntlm.c
@@ -0,0 +1,421 @@
+/*
+ *  ntlm proxy support for OpenVPN
+ *
+ *  Copyright (C) 2004 William Preston
+ *
+ *  *NTLMv2 support and domain name parsing by Miroslav Zajic, Nextsoft s.r.o.*
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if NTLM
+
+#include "common.h"
+#include "buffer.h"
+#include "misc.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "proxy.h"
+#include "ntlm.h"
+#include "base64.h"
+#include "crypto.h"
+
+#include "memdbg.h"
+
+
+/* 64bit datatype macros */
+#ifdef _MSC_VER
+/* MS compilers */
+#define UINTEGER64 __int64
+#define UINT64(c) c ## Ui64
+#else
+/* Non MS compilers */
+#define UINTEGER64 unsigned long long
+#define UINT64(c) c ## LL
+#endif
+
+
+
+static void
+create_des_keys(const unsigned char *hash, unsigned char *key)
+{
+    key[0] = hash[0];
+    key[1] = ((hash[0] & 1) << 7) | (hash[1] >> 1);
+    key[2] = ((hash[1] & 3) << 6) | (hash[2] >> 2);
+    key[3] = ((hash[2] & 7) << 5) | (hash[3] >> 3);
+    key[4] = ((hash[3] & 15) << 4) | (hash[4] >> 4);
+    key[5] = ((hash[4] & 31) << 3) | (hash[5] >> 5);
+    key[6] = ((hash[5] & 63) << 2) | (hash[6] >> 6);
+    key[7] = ((hash[6] & 127) << 1);
+    key_des_fixup(key, 8, 1);
+}
+
+static void
+gen_md4_hash(const uint8_t *data, int data_len, uint8_t *result)
+{
+    /* result is 16 byte md4 hash */
+    const md_kt_t *md4_kt = md_kt_get("MD4");
+    uint8_t md[MD4_DIGEST_LENGTH];
+
+    md_full(md4_kt, data, data_len, md);
+    memcpy(result, md, MD4_DIGEST_LENGTH);
+}
+
+static void
+gen_hmac_md5(const uint8_t *data, int data_len, const uint8_t *key, int key_len,
+             uint8_t *result)
+{
+    const md_kt_t *md5_kt = md_kt_get("MD5");
+    hmac_ctx_t *hmac_ctx = hmac_ctx_new();
+
+    hmac_ctx_init(hmac_ctx, key, key_len, md5_kt);
+    hmac_ctx_update(hmac_ctx, data, data_len);
+    hmac_ctx_final(hmac_ctx, result);
+    hmac_ctx_cleanup(hmac_ctx);
+    hmac_ctx_free(hmac_ctx);
+}
+
+static void
+gen_timestamp(uint8_t *timestamp)
+{
+    /* Copies 8 bytes long timestamp into "timestamp" buffer.
+     * Timestamp is Little-endian, 64-bit signed value representing the
+     * number of tenths of a microsecond since January 1, 1601.
+     */
+
+    UINTEGER64 timestamp_ull;
+
+    timestamp_ull = openvpn_time(NULL);
+    timestamp_ull = (timestamp_ull + UINT64(11644473600)) * UINT64(10000000);
+
+    /* store little endian value */
+    timestamp[0] = timestamp_ull & UINT64(0xFF);
+    timestamp[1] = (timestamp_ull  >> 8)  & UINT64(0xFF);
+    timestamp[2] = (timestamp_ull  >> 16) & UINT64(0xFF);
+    timestamp[3] = (timestamp_ull  >> 24) & UINT64(0xFF);
+    timestamp[4] = (timestamp_ull  >> 32) & UINT64(0xFF);
+    timestamp[5] = (timestamp_ull  >> 40) & UINT64(0xFF);
+    timestamp[6] = (timestamp_ull  >> 48) & UINT64(0xFF);
+    timestamp[7] = (timestamp_ull  >> 56) & UINT64(0xFF);
+}
+
+static void
+gen_nonce(unsigned char *nonce)
+{
+    /* Generates 8 random bytes to be used as client nonce */
+    int i;
+
+    for (i = 0; i<8; i++)
+    {
+        nonce[i] = (unsigned char)get_random();
+    }
+}
+
+static void
+my_strupr(char *str)
+{
+    /* converts string to uppercase in place */
+
+    while (*str)
+    {
+        *str = toupper(*str);
+        str++;
+    }
+}
+
+static int
+unicodize(char *dst, const char *src)
+{
+    /* not really unicode... */
+    int i = 0;
+    do
+    {
+        dst[i++] = *src;
+        dst[i++] = 0;
+    } while (*src++);
+
+    return i;
+}
+
+static void
+add_security_buffer(int sb_offset, void *data, int length,
+                    unsigned char *msg_buf, int *msg_bufpos)
+{
+    /* Adds security buffer data to a message and sets security buffer's
+     * offset and length */
+    msg_buf[sb_offset] = (unsigned char)length;
+    msg_buf[sb_offset + 2] = msg_buf[sb_offset];
+    msg_buf[sb_offset + 4] = (unsigned char)(*msg_bufpos & 0xff);
+    msg_buf[sb_offset + 5] = (unsigned char)((*msg_bufpos >> 8) & 0xff);
+    memcpy(&msg_buf[*msg_bufpos], data, msg_buf[sb_offset]);
+    *msg_bufpos += length;
+}
+
+const char *
+ntlm_phase_1(const struct http_proxy_info *p, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(96, gc);
+    /* try a minimal NTLM handshake
+     *
+     * http://davenport.sourceforge.net/ntlm.html
+     *
+     * This message contains only the NTLMSSP signature,
+     * the NTLM message type,
+     * and the minimal set of flags (Negotiate NTLM and Negotiate OEM).
+     *
+     */
+    buf_printf(&out, "%s", "TlRMTVNTUAABAAAAAgIAAA==");
+    return (BSTR(&out));
+}
+
+const char *
+ntlm_phase_3(const struct http_proxy_info *p, const char *phase_2,
+             struct gc_arena *gc)
+{
+    /* NTLM handshake
+     *
+     * http://davenport.sourceforge.net/ntlm.html
+     *
+     */
+
+    char pwbuf[sizeof(p->up.password) * 2]; /* for unicode password */
+    uint8_t buf2[128]; /* decoded reply from proxy */
+    uint8_t phase3[464];
+
+    uint8_t md4_hash[MD4_DIGEST_LENGTH + 5];
+    uint8_t challenge[8], ntlm_response[24];
+    int i, ret_val;
+
+    uint8_t ntlmv2_response[144];
+    char userdomain_u[256];     /* for uppercase unicode username and domain */
+    char userdomain[128];       /* the same as previous but ascii */
+    uint8_t ntlmv2_hash[MD5_DIGEST_LENGTH];
+    uint8_t ntlmv2_hmacmd5[16];
+    uint8_t *ntlmv2_blob = ntlmv2_response + 16;     /* inside ntlmv2_response, length: 128 */
+    int ntlmv2_blob_size = 0;
+    int phase3_bufpos = 0x40;     /* offset to next security buffer data to be added */
+    size_t len;
+
+    char domain[128];
+    char username[128];
+    char *separator;
+
+    bool ntlmv2_enabled = (p->auth_method == HTTP_AUTH_NTLM2);
+
+    CLEAR(buf2);
+
+    ASSERT(strlen(p->up.username) > 0);
+    ASSERT(strlen(p->up.password) > 0);
+
+    /* username parsing */
+    separator = strchr(p->up.username, '\\');
+    if (separator == NULL)
+    {
+        strncpy(username, p->up.username, sizeof(username)-1);
+        username[sizeof(username)-1] = 0;
+        domain[0] = 0;
+    }
+    else
+    {
+        strncpy(username, separator+1, sizeof(username)-1);
+        username[sizeof(username)-1] = 0;
+        len = separator - p->up.username;
+        if (len > sizeof(domain) - 1)
+        {
+            len = sizeof(domain) - 1;
+        }
+        strncpy(domain, p->up.username,  len);
+        domain[len] = 0;
+    }
+
+
+    /* fill 1st 16 bytes with md4 hash, disregard terminating null */
+    int unicode_len = unicodize(pwbuf, p->up.password) - 2;
+    gen_md4_hash((uint8_t *)pwbuf, unicode_len, md4_hash);
+
+    /* pad to 21 bytes */
+    memset(md4_hash + MD4_DIGEST_LENGTH, 0, 5);
+
+    ret_val = openvpn_base64_decode(phase_2, buf2, -1);
+    if (ret_val < 0)
+    {
+        return NULL;
+    }
+
+    /* we can be sure that phase_2 is less than 128
+     * therefore buf2 needs to be (3/4 * 128) */
+
+    /* extract the challenge from bytes 24-31 */
+    for (i = 0; i<8; i++)
+    {
+        challenge[i] = buf2[i+24];
+    }
+
+    if (ntlmv2_enabled)      /* Generate NTLMv2 response */
+    {
+        int tib_len;
+
+        /* NTLMv2 hash */
+        strcpy(userdomain, username);
+        my_strupr(userdomain);
+        if (strlen(username) + strlen(domain) < sizeof(userdomain))
+        {
+            strcat(userdomain, domain);
+        }
+        else
+        {
+            msg(M_INFO, "Warning: Username or domain too long");
+        }
+        unicodize(userdomain_u, userdomain);
+        gen_hmac_md5((uint8_t *)userdomain_u, 2 * strlen(userdomain), md4_hash,
+                     MD5_DIGEST_LENGTH, ntlmv2_hash);
+
+        /* NTLMv2 Blob */
+        memset(ntlmv2_blob, 0, 128);                        /* Clear blob buffer */
+        ntlmv2_blob[0x00] = 1;                              /* Signature */
+        ntlmv2_blob[0x01] = 1;                              /* Signature */
+        ntlmv2_blob[0x04] = 0;                              /* Reserved */
+        gen_timestamp(&ntlmv2_blob[0x08]);                  /* 64-bit Timestamp */
+        gen_nonce(&ntlmv2_blob[0x10]);                      /* 64-bit Client Nonce */
+        ntlmv2_blob[0x18] = 0;                              /* Unknown, zero should work */
+
+        /* Add target information block to the blob */
+
+        /* Check for Target Information block */
+        /* The NTLM spec instructs to interpret these 4 consecutive bytes as a
+         * 32bit long integer. However, no endianness is specified.
+         * The code here and that found in other NTLM implementations point
+         * towards the assumption that the byte order on the wire has to
+         * match the order on the sending and receiving hosts. Probably NTLM has
+         * been thought to be always running on x86_64/i386 machine thus
+         * implying Little-Endian everywhere.
+         *
+         * This said, in case of future changes, we should keep in mind that the
+         * byte order on the wire for the NTLM header is LE.
+         */
+        const size_t hoff = 0x14;
+        unsigned long flags = buf2[hoff] | (buf2[hoff + 1] << 8) |
+                              (buf2[hoff + 2] << 16) | (buf2[hoff + 3] << 24);
+        if ((flags & 0x00800000) == 0x00800000)
+        {
+            tib_len = buf2[0x28];            /* Get Target Information block size */
+            if (tib_len > 96)
+            {
+                tib_len = 96;
+            }
+
+            {
+                uint8_t *tib_ptr;
+                uint8_t tib_pos = buf2[0x2c];
+                if (tib_pos + tib_len > sizeof(buf2))
+                {
+                    return NULL;
+                }
+                /* Get Target Information block pointer */
+                tib_ptr = buf2 + tib_pos;
+                /* Copy Target Information block into the blob */
+                memcpy(&ntlmv2_blob[0x1c], tib_ptr, tib_len);
+            }
+        }
+        else
+        {
+            tib_len = 0;
+        }
+
+        /* Unknown, zero works */
+        ntlmv2_blob[0x1c + tib_len] = 0;
+
+        /* Get blob length */
+        ntlmv2_blob_size = 0x20 + tib_len;
+
+        /* Add challenge from message 2 */
+        memcpy(&ntlmv2_response[8], challenge, 8);
+
+        /* hmac-md5 */
+        gen_hmac_md5(&ntlmv2_response[8], ntlmv2_blob_size + 8, ntlmv2_hash,
+                     MD5_DIGEST_LENGTH, ntlmv2_hmacmd5);
+
+        /* Add hmac-md5 result to the blob.
+         * Note: This overwrites challenge previously written at
+         * ntlmv2_response[8..15] */
+        memcpy(ntlmv2_response, ntlmv2_hmacmd5, MD5_DIGEST_LENGTH);
+    }
+    else /* Generate NTLM response */
+    {
+        unsigned char key1[DES_KEY_LENGTH], key2[DES_KEY_LENGTH];
+        unsigned char key3[DES_KEY_LENGTH];
+
+        create_des_keys(md4_hash, key1);
+        cipher_des_encrypt_ecb(key1, challenge, ntlm_response);
+
+        create_des_keys(&md4_hash[DES_KEY_LENGTH - 1], key2);
+        cipher_des_encrypt_ecb(key2, challenge, &ntlm_response[DES_KEY_LENGTH]);
+
+        create_des_keys(&md4_hash[2 * (DES_KEY_LENGTH - 1)], key3);
+        cipher_des_encrypt_ecb(key3, challenge,
+                               &ntlm_response[DES_KEY_LENGTH * 2]);
+    }
+
+
+    memset(phase3, 0, sizeof(phase3));       /* clear reply */
+
+    strcpy((char *)phase3, "NTLMSSP\0");      /* signature */
+    phase3[8] = 3;     /* type 3 */
+
+    if (ntlmv2_enabled)      /* NTLMv2 response */
+    {
+        add_security_buffer(0x14, ntlmv2_response, ntlmv2_blob_size + 16,
+                            phase3, &phase3_bufpos);
+    }
+    else       /* NTLM response */
+    {
+        add_security_buffer(0x14, ntlm_response, 24, phase3, &phase3_bufpos);
+    }
+
+    /* username in ascii */
+    add_security_buffer(0x24, username, strlen(username), phase3,
+                        &phase3_bufpos);
+
+    /* Set domain. If <domain> is empty, default domain will be used
+     * (i.e. proxy's domain) */
+    add_security_buffer(0x1c, domain, strlen(domain), phase3, &phase3_bufpos);
+
+    /* other security buffers will be empty */
+    phase3[0x10] = phase3_bufpos;     /* lm not used */
+    phase3[0x30] = phase3_bufpos;     /* no workstation name supplied */
+    phase3[0x38] = phase3_bufpos;     /* no session key */
+
+    /* flags */
+    phase3[0x3c] = 0x02; /* negotiate oem */
+    phase3[0x3d] = 0x02; /* negotiate ntlm */
+
+    return ((const char *)make_base64_string2((unsigned char *)phase3,
+                                              phase3_bufpos, gc));
+}
+
+#else  /* if NTLM */
+static void
+dummy(void)
+{
+}
+#endif /* if NTLM */
diff --git a/src/openvpn/ntlm.h b/src/openvpn/ntlm.h
new file mode 100644
index 0000000..b0a6821
--- /dev/null
+++ b/src/openvpn/ntlm.h
@@ -0,0 +1,12 @@
+#ifndef NTLM_H
+#define NTLM_H
+
+#if NTLM
+
+const char *ntlm_phase_1(const struct http_proxy_info *p, struct gc_arena *gc);
+
+const char *ntlm_phase_3(const struct http_proxy_info *p, const char *phase_2, struct gc_arena *gc);
+
+#endif
+
+#endif
diff --git a/src/openvpn/occ-inline.h b/src/openvpn/occ-inline.h
new file mode 100644
index 0000000..7f6f1b2
--- /dev/null
+++ b/src/openvpn/occ-inline.h
@@ -0,0 +1,95 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OCC_INLINE_H
+#define OCC_INLINE_H
+
+#ifdef ENABLE_OCC
+
+/*
+ * Inline functions
+ */
+
+static inline int
+occ_reset_op(void)
+{
+    return -1;
+}
+
+/*
+ * Should we send an OCC_REQUEST message?
+ */
+static inline void
+check_send_occ_req(struct context *c)
+{
+    void check_send_occ_req_dowork(struct context *c);
+
+    if (event_timeout_defined(&c->c2.occ_interval)
+        && event_timeout_trigger(&c->c2.occ_interval,
+                                 &c->c2.timeval,
+                                 (!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
+    {
+        check_send_occ_req_dowork(c);
+    }
+}
+
+/*
+ * Should we send an MTU load test?
+ */
+static inline void
+check_send_occ_load_test(struct context *c)
+{
+    void check_send_occ_load_test_dowork(struct context *c);
+
+    if (event_timeout_defined(&c->c2.occ_mtu_load_test_interval)
+        && event_timeout_trigger(&c->c2.occ_mtu_load_test_interval,
+                                 &c->c2.timeval,
+                                 (!TO_LINK_DEF(c) && c->c2.occ_op < 0) ? ETT_DEFAULT : 0))
+    {
+        check_send_occ_load_test_dowork(c);
+    }
+}
+
+/*
+ * Should we send an OCC message?
+ */
+static inline void
+check_send_occ_msg(struct context *c)
+{
+    void check_send_occ_msg_dowork(struct context *c);
+
+    if (c->c2.occ_op >= 0)
+    {
+        if (!TO_LINK_DEF(c))
+        {
+            check_send_occ_msg_dowork(c);
+        }
+        else
+        {
+            tv_clear(&c->c2.timeval); /* ZERO-TIMEOUT */
+        }
+    }
+}
+
+#endif /* ifdef ENABLE_OCC */
+#endif /* ifndef OCC_INLINE_H */
diff --git a/src/openvpn/occ.c b/src/openvpn/occ.c
new file mode 100644
index 0000000..80504af
--- /dev/null
+++ b/src/openvpn/occ.c
@@ -0,0 +1,435 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_OCC
+
+#include "occ.h"
+
+#include "memdbg.h"
+
+#include "forward-inline.h"
+#include "occ-inline.h"
+
+/*
+ * This random string identifies an OpenVPN
+ * Configuration Control packet.
+ * It should be of sufficient length and randomness
+ * so as not to collide with other tunnel data.
+ *
+ * The OCC protocol is as follows:
+ *
+ * occ_magic -- (16 octets)
+ *
+ * type [OCC_REQUEST | OCC_REPLY] (1 octet)
+ * null terminated options string if OCC_REPLY (variable)
+ *
+ * When encryption is used, the OCC packet
+ * is encapsulated within the encrypted
+ * envelope.
+ *
+ * OCC_STRING_SIZE must be set to sizeof (occ_magic)
+ */
+
+const uint8_t occ_magic[] = {
+    0x28, 0x7f, 0x34, 0x6b, 0xd4, 0xef, 0x7a, 0x81,
+    0x2d, 0x56, 0xb8, 0xd3, 0xaf, 0xc5, 0x45, 0x9c
+};
+
+static const struct mtu_load_test mtu_load_test_sequence[] = {
+
+    {OCC_MTU_LOAD_REQUEST, -1000},
+    {OCC_MTU_LOAD, -1000},
+    {OCC_MTU_LOAD_REQUEST, -1000},
+    {OCC_MTU_LOAD, -1000},
+    {OCC_MTU_LOAD_REQUEST, -1000},
+    {OCC_MTU_LOAD, -1000},
+
+    {OCC_MTU_LOAD_REQUEST, -750},
+    {OCC_MTU_LOAD, -750},
+    {OCC_MTU_LOAD_REQUEST, -750},
+    {OCC_MTU_LOAD, -750},
+    {OCC_MTU_LOAD_REQUEST, -750},
+    {OCC_MTU_LOAD, -750},
+
+    {OCC_MTU_LOAD_REQUEST, -500},
+    {OCC_MTU_LOAD, -500},
+    {OCC_MTU_LOAD_REQUEST, -500},
+    {OCC_MTU_LOAD, -500},
+    {OCC_MTU_LOAD_REQUEST, -500},
+    {OCC_MTU_LOAD, -500},
+
+    {OCC_MTU_LOAD_REQUEST, -400},
+    {OCC_MTU_LOAD, -400},
+    {OCC_MTU_LOAD_REQUEST, -400},
+    {OCC_MTU_LOAD, -400},
+    {OCC_MTU_LOAD_REQUEST, -400},
+    {OCC_MTU_LOAD, -400},
+
+    {OCC_MTU_LOAD_REQUEST, -300},
+    {OCC_MTU_LOAD, -300},
+    {OCC_MTU_LOAD_REQUEST, -300},
+    {OCC_MTU_LOAD, -300},
+    {OCC_MTU_LOAD_REQUEST, -300},
+    {OCC_MTU_LOAD, -300},
+
+    {OCC_MTU_LOAD_REQUEST, -200},
+    {OCC_MTU_LOAD, -200},
+    {OCC_MTU_LOAD_REQUEST, -200},
+    {OCC_MTU_LOAD, -200},
+    {OCC_MTU_LOAD_REQUEST, -200},
+    {OCC_MTU_LOAD, -200},
+
+    {OCC_MTU_LOAD_REQUEST, -150},
+    {OCC_MTU_LOAD, -150},
+    {OCC_MTU_LOAD_REQUEST, -150},
+    {OCC_MTU_LOAD, -150},
+    {OCC_MTU_LOAD_REQUEST, -150},
+    {OCC_MTU_LOAD, -150},
+
+    {OCC_MTU_LOAD_REQUEST, -100},
+    {OCC_MTU_LOAD, -100},
+    {OCC_MTU_LOAD_REQUEST, -100},
+    {OCC_MTU_LOAD, -100},
+    {OCC_MTU_LOAD_REQUEST, -100},
+    {OCC_MTU_LOAD, -100},
+
+    {OCC_MTU_LOAD_REQUEST, -50},
+    {OCC_MTU_LOAD, -50},
+    {OCC_MTU_LOAD_REQUEST, -50},
+    {OCC_MTU_LOAD, -50},
+    {OCC_MTU_LOAD_REQUEST, -50},
+    {OCC_MTU_LOAD, -50},
+
+    {OCC_MTU_LOAD_REQUEST, 0},
+    {OCC_MTU_LOAD, 0},
+    {OCC_MTU_LOAD_REQUEST, 0},
+    {OCC_MTU_LOAD, 0},
+    {OCC_MTU_LOAD_REQUEST, 0},
+    {OCC_MTU_LOAD, 0},
+
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+    {OCC_MTU_REQUEST, 0},
+
+    {-1, 0}
+};
+
+void
+check_send_occ_req_dowork(struct context *c)
+{
+    if (++c->c2.occ_n_tries >= OCC_N_TRIES)
+    {
+        if (c->options.ce.remote)
+        {
+            /*
+             * No OCC_REPLY from peer after repeated attempts.
+             * Give up.
+             */
+            msg(D_SHOW_OCC,
+                "NOTE: failed to obtain options consistency info from peer -- "
+                "this could occur if the remote peer is running a version of "
+                PACKAGE_NAME
+                " before 1.5-beta8 or if there is a network connectivity problem, and will not necessarily prevent "
+                PACKAGE_NAME
+                " from running (" counter_format " bytes received from peer, " counter_format
+                " bytes authenticated data channel traffic) -- you can disable the options consistency "
+                "check with --disable-occ.",
+                c->c2.link_read_bytes,
+                c->c2.link_read_bytes_auth);
+        }
+        event_timeout_clear(&c->c2.occ_interval);
+    }
+    else
+    {
+        c->c2.occ_op = OCC_REQUEST;
+
+        /*
+         * If we don't hear back from peer, send another
+         * OCC_REQUEST in OCC_INTERVAL_SECONDS.
+         */
+        event_timeout_reset(&c->c2.occ_interval);
+    }
+}
+
+void
+check_send_occ_load_test_dowork(struct context *c)
+{
+    if (CONNECTION_ESTABLISHED(c))
+    {
+        const struct mtu_load_test *entry;
+
+        if (!c->c2.occ_mtu_load_n_tries)
+        {
+            msg(M_INFO,
+                "NOTE: Beginning empirical MTU test -- results should be available in 3 to 4 minutes.");
+        }
+
+        entry = &mtu_load_test_sequence[c->c2.occ_mtu_load_n_tries++];
+        if (entry->op >= 0)
+        {
+            c->c2.occ_op = entry->op;
+            c->c2.occ_mtu_load_size =
+                EXPANDED_SIZE(&c->c2.frame) + entry->delta;
+        }
+        else
+        {
+            msg(M_INFO,
+                "NOTE: failed to empirically measure MTU (requires " PACKAGE_NAME " 1.5 or higher at other end of connection).");
+            event_timeout_clear(&c->c2.occ_mtu_load_test_interval);
+            c->c2.occ_mtu_load_n_tries = 0;
+        }
+    }
+}
+
+void
+check_send_occ_msg_dowork(struct context *c)
+{
+    bool doit = false;
+
+    c->c2.buf = c->c2.buffers->aux_buf;
+    ASSERT(buf_init(&c->c2.buf, FRAME_HEADROOM(&c->c2.frame)));
+    ASSERT(buf_safe(&c->c2.buf, MAX_RW_SIZE_TUN(&c->c2.frame)));
+    ASSERT(buf_write(&c->c2.buf, occ_magic, OCC_STRING_SIZE));
+
+    switch (c->c2.occ_op)
+    {
+        case OCC_REQUEST:
+            if (!buf_write_u8(&c->c2.buf, OCC_REQUEST))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_REQUEST");
+            doit = true;
+            break;
+
+        case OCC_REPLY:
+            if (!c->c2.options_string_local)
+            {
+                break;
+            }
+            if (!buf_write_u8(&c->c2.buf, OCC_REPLY))
+            {
+                break;
+            }
+            if (!buf_write(&c->c2.buf, c->c2.options_string_local,
+                           strlen(c->c2.options_string_local) + 1))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_REPLY");
+            doit = true;
+            break;
+
+        case OCC_MTU_REQUEST:
+            if (!buf_write_u8(&c->c2.buf, OCC_MTU_REQUEST))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_MTU_REQUEST");
+            doit = true;
+            break;
+
+        case OCC_MTU_REPLY:
+            if (!buf_write_u8(&c->c2.buf, OCC_MTU_REPLY))
+            {
+                break;
+            }
+            if (!buf_write_u16(&c->c2.buf, c->c2.max_recv_size_local))
+            {
+                break;
+            }
+            if (!buf_write_u16(&c->c2.buf, c->c2.max_send_size_local))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_MTU_REPLY");
+            doit = true;
+            break;
+
+        case OCC_MTU_LOAD_REQUEST:
+            if (!buf_write_u8(&c->c2.buf, OCC_MTU_LOAD_REQUEST))
+            {
+                break;
+            }
+            if (!buf_write_u16(&c->c2.buf, c->c2.occ_mtu_load_size))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_MTU_LOAD_REQUEST");
+            doit = true;
+            break;
+
+        case OCC_MTU_LOAD:
+        {
+            int need_to_add;
+
+            if (!buf_write_u8(&c->c2.buf, OCC_MTU_LOAD))
+            {
+                break;
+            }
+            need_to_add = min_int(c->c2.occ_mtu_load_size, EXPANDED_SIZE(&c->c2.frame))
+                          - OCC_STRING_SIZE
+                          - sizeof(uint8_t)
+                          - EXTRA_FRAME(&c->c2.frame);
+
+            while (need_to_add > 0)
+            {
+                /*
+                 * Fill the load test packet with pseudo-random bytes.
+                 */
+                if (!buf_write_u8(&c->c2.buf, get_random() & 0xFF))
+                {
+                    break;
+                }
+                --need_to_add;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_MTU_LOAD min_int(%d-%d-%d-%d,%d) size=%d",
+                 c->c2.occ_mtu_load_size,
+                 OCC_STRING_SIZE,
+                 (int) sizeof(uint8_t),
+                 EXTRA_FRAME(&c->c2.frame),
+                 MAX_RW_SIZE_TUN(&c->c2.frame),
+                 BLEN(&c->c2.buf));
+            doit = true;
+        }
+        break;
+
+        case OCC_EXIT:
+            if (!buf_write_u8(&c->c2.buf, OCC_EXIT))
+            {
+                break;
+            }
+            dmsg(D_PACKET_CONTENT, "SENT OCC_EXIT");
+            doit = true;
+            break;
+    }
+
+    if (doit)
+    {
+        /*
+         * We will treat the packet like any other outgoing packet,
+         * compress, encrypt, sign, etc.
+         */
+        encrypt_sign(c, true);
+    }
+
+    c->c2.occ_op = -1;
+}
+
+void
+process_received_occ_msg(struct context *c)
+{
+    ASSERT(buf_advance(&c->c2.buf, OCC_STRING_SIZE));
+    switch (buf_read_u8(&c->c2.buf))
+    {
+        case OCC_REQUEST:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_REQUEST");
+            c->c2.occ_op = OCC_REPLY;
+            break;
+
+        case OCC_MTU_REQUEST:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_MTU_REQUEST");
+            c->c2.occ_op = OCC_MTU_REPLY;
+            break;
+
+        case OCC_MTU_LOAD_REQUEST:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_MTU_LOAD_REQUEST");
+            c->c2.occ_mtu_load_size = buf_read_u16(&c->c2.buf);
+            if (c->c2.occ_mtu_load_size >= 0)
+            {
+                c->c2.occ_op = OCC_MTU_LOAD;
+            }
+            break;
+
+        case OCC_REPLY:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_REPLY");
+            if (c->options.occ && !TLS_MODE(c) && c->c2.options_string_remote)
+            {
+                if (!options_cmp_equal_safe((char *) BPTR(&c->c2.buf),
+                                            c->c2.options_string_remote,
+                                            c->c2.buf.len))
+                {
+                    options_warning_safe((char *) BPTR(&c->c2.buf),
+                                         c->c2.options_string_remote,
+                                         c->c2.buf.len);
+                }
+            }
+            event_timeout_clear(&c->c2.occ_interval);
+            break;
+
+        case OCC_MTU_REPLY:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_MTU_REPLY");
+            c->c2.max_recv_size_remote = buf_read_u16(&c->c2.buf);
+            c->c2.max_send_size_remote = buf_read_u16(&c->c2.buf);
+            if (c->options.mtu_test
+                && c->c2.max_recv_size_remote > 0
+                && c->c2.max_send_size_remote > 0)
+            {
+                msg(M_INFO, "NOTE: Empirical MTU test completed [Tried,Actual] local->remote=[%d,%d] remote->local=[%d,%d]",
+                    c->c2.max_send_size_local,
+                    c->c2.max_recv_size_remote,
+                    c->c2.max_send_size_remote,
+                    c->c2.max_recv_size_local);
+                if (!c->options.ce.fragment
+                    && (proto_is_dgram(c->options.ce.proto))
+                    && c->c2.max_send_size_local > TUN_MTU_MIN
+                    && (c->c2.max_recv_size_remote < c->c2.max_send_size_local
+                        || c->c2.max_recv_size_local < c->c2.max_send_size_remote))
+                {
+                    msg(M_INFO, "NOTE: This connection is unable to accommodate a UDP packet size of %d. Consider using --fragment or --mssfix options as a workaround.",
+                        c->c2.max_send_size_local);
+                }
+            }
+            event_timeout_clear(&c->c2.occ_mtu_load_test_interval);
+            break;
+
+        case OCC_EXIT:
+            dmsg(D_PACKET_CONTENT, "RECEIVED OCC_EXIT");
+            c->sig->signal_received = SIGTERM;
+            c->sig->signal_text = "remote-exit";
+            break;
+    }
+    c->c2.buf.len = 0; /* don't pass packet on */
+}
+
+#else  /* ifdef ENABLE_OCC */
+static void
+dummy(void)
+{
+}
+#endif /* ifdef ENABLE_OCC */
diff --git a/src/openvpn/occ.h b/src/openvpn/occ.h
new file mode 100644
index 0000000..f6ff5f9
--- /dev/null
+++ b/src/openvpn/occ.h
@@ -0,0 +1,94 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OCC_H
+#define OCC_H
+
+#ifdef ENABLE_OCC
+
+#include "forward.h"
+
+/* OCC_STRING_SIZE must be set to sizeof (occ_magic) */
+#define OCC_STRING_SIZE 16
+
+/*
+ * OCC (OpenVPN Configuration Control) protocol opcodes.
+ */
+
+#define OCC_REQUEST   0         /* request options string from peer */
+#define OCC_REPLY     1         /* deliver options string to peer */
+
+/*
+ * Send an OCC_REQUEST once every OCC_INTERVAL
+ * seconds until a reply is received.
+ *
+ * If we haven't received a reply after
+ * OCC_N_TRIES, give up.
+ */
+#define OCC_INTERVAL_SECONDS 10
+#define OCC_N_TRIES          12
+
+/*
+ * Other OCC protocol opcodes used to estimate the MTU empirically.
+ */
+#define OCC_MTU_LOAD_REQUEST   2        /* Ask peer to send a big packet to us */
+#define OCC_MTU_LOAD           3        /* Send a big packet to peer */
+#define OCC_MTU_REQUEST        4        /* Ask peer to tell us the largest
+                                         * packet it has received from us so far */
+#define OCC_MTU_REPLY          5        /* Send largest packet size to peer */
+
+/*
+ * Process one command from mtu_load_test_sequence
+ * once every n seconds, if --mtu-test is specified.
+ */
+#define OCC_MTU_LOAD_INTERVAL_SECONDS 3
+
+/*
+ * Send an exit message to remote.
+ */
+#define OCC_EXIT               6
+
+/*
+ * Used to conduct a load test command sequence
+ * of UDP connection for empirical MTU measurement.
+ */
+struct mtu_load_test
+{
+    int op;                     /* OCC opcode to send to peer */
+    int delta;                  /* determine packet size to send by using
+                                 * this delta against currently
+                                 * configured MTU */
+};
+
+extern const uint8_t occ_magic[];
+
+static inline bool
+is_occ_msg(const struct buffer *buf)
+{
+    return buf_string_match_head(buf, occ_magic, OCC_STRING_SIZE);
+}
+
+void process_received_occ_msg(struct context *c);
+
+#endif /* ifdef ENABLE_OCC */
+#endif /* ifndef OCC_H */
diff --git a/src/openvpn/openssl_compat.h b/src/openvpn/openssl_compat.h
new file mode 100644
index 0000000..8acc7d1
--- /dev/null
+++ b/src/openvpn/openssl_compat.h
@@ -0,0 +1,808 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file OpenSSL compatibility stub
+ *
+ * This file provide compatibility stubs for the OpenSSL libraries
+ * prior to version 1.1. This version introduces many changes in the
+ * library interface, including the fact that various objects and
+ * structures are not fully opaque.
+ */
+
+#ifndef OPENSSL_COMPAT_H_
+#define OPENSSL_COMPAT_H_
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "buffer.h"
+
+#include <openssl/ssl.h>
+#include <openssl/x509.h>
+
+#if !defined(HAVE_EVP_MD_CTX_RESET)
+/**
+ * Reset a message digest context
+ *
+ * @param ctx                 The message digest context
+ * @return                    1 on success, 0 on error
+ */
+static inline int
+EVP_MD_CTX_reset(EVP_MD_CTX *ctx)
+{
+    EVP_MD_CTX_cleanup(ctx);
+    return 1;
+}
+#endif
+
+#if !defined(HAVE_EVP_MD_CTX_FREE)
+/**
+ * Free an existing message digest context
+ *
+ * @param ctx                 The message digest context
+ */
+static inline void
+EVP_MD_CTX_free(EVP_MD_CTX *ctx)
+{
+    free(ctx);
+}
+#endif
+
+#if !defined(HAVE_EVP_MD_CTX_NEW)
+/**
+ * Allocate a new message digest object
+ *
+ * @return                    A zero'ed message digest object
+ */
+static inline EVP_MD_CTX *
+EVP_MD_CTX_new(void)
+{
+    EVP_MD_CTX *ctx = NULL;
+    ALLOC_OBJ_CLEAR(ctx, EVP_MD_CTX);
+    return ctx;
+}
+#endif
+
+#if !defined(HAVE_EVP_CIPHER_CTX_RESET)
+#define EVP_CIPHER_CTX_reset EVP_CIPHER_CTX_init
+#endif
+
+#if !defined(HAVE_X509_GET0_NOTBEFORE)
+#define X509_get0_notBefore X509_get_notBefore
+#endif
+
+#if !defined(HAVE_X509_GET0_NOTAFTER)
+#define X509_get0_notAfter X509_get_notAfter
+#endif
+
+#if !defined(HAVE_HMAC_CTX_RESET)
+/**
+ * Reset a HMAC context
+ *
+ * OpenSSL 1.1+ removes APIs HMAC_CTX_init() and HMAC_CTX_cleanup()
+ * and replace them with a single call that does a cleanup followed
+ * by an init. A proper _reset() for OpenSSL < 1.1 should perform
+ * a similar set of operations.
+ *
+ * It means that before we kill a HMAC context, we'll have to cleanup
+ * again, as we probably have allocated a few resources when we forced
+ * an init.
+ *
+ * @param ctx                 The HMAC context
+ * @return                    1 on success, 0 on error
+ */
+static inline int
+HMAC_CTX_reset(HMAC_CTX *ctx)
+{
+    HMAC_CTX_cleanup(ctx);
+    HMAC_CTX_init(ctx);
+    return 1;
+}
+#endif
+
+#if !defined(HAVE_HMAC_CTX_FREE)
+/**
+ * Cleanup and free an existing HMAC context
+ *
+ * @param ctx                 The HMAC context
+ */
+static inline void
+HMAC_CTX_free(HMAC_CTX *ctx)
+{
+    HMAC_CTX_cleanup(ctx);
+    free(ctx);
+}
+#endif
+
+#if !defined(HAVE_HMAC_CTX_NEW)
+/**
+ * Allocate a new HMAC context object
+ *
+ * @return                    A zero'ed HMAC context object
+ */
+static inline HMAC_CTX *
+HMAC_CTX_new(void)
+{
+    HMAC_CTX *ctx = NULL;
+    ALLOC_OBJ_CLEAR(ctx, HMAC_CTX);
+    return ctx;
+}
+#endif
+
+#if !defined(HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB_USERDATA)
+/**
+ * Fetch the default password callback user data from the SSL context
+ *
+ * @param ctx                SSL context
+ * @return                   The password callback user data
+ */
+static inline void *
+SSL_CTX_get_default_passwd_cb_userdata(SSL_CTX *ctx)
+{
+    return ctx ? ctx->default_passwd_callback_userdata : NULL;
+}
+#endif
+
+#if !defined(HAVE_SSL_CTX_GET_DEFAULT_PASSWD_CB)
+/**
+ * Fetch the default password callback from the SSL context
+ *
+ * @param ctx                SSL context
+ * @return                   The password callback
+ */
+static inline pem_password_cb *
+SSL_CTX_get_default_passwd_cb(SSL_CTX *ctx)
+{
+    return ctx ? ctx->default_passwd_callback : NULL;
+}
+#endif
+
+#if !defined(HAVE_X509_GET0_PUBKEY)
+/**
+ * Get the public key from a X509 certificate
+ *
+ * @param x                  X509 certificate
+ * @return                   The certificate public key
+ */
+static inline EVP_PKEY *
+X509_get0_pubkey(const X509 *x)
+{
+    return (x && x->cert_info && x->cert_info->key) ?
+           x->cert_info->key->pkey : NULL;
+}
+#endif
+
+#if !defined(HAVE_X509_STORE_GET0_OBJECTS)
+/**
+ * Fetch the X509 object stack from the X509 store
+ *
+ * @param store              X509 object store
+ * @return                   the X509 object stack
+ */
+static inline STACK_OF(X509_OBJECT) *
+X509_STORE_get0_objects(X509_STORE *store)
+{
+    return store ? store->objs : NULL;
+}
+#endif
+
+#if !defined(HAVE_X509_OBJECT_FREE)
+/**
+ * Destroy a X509 object
+ *
+ * @param obj                X509 object
+ */
+static inline void
+X509_OBJECT_free(X509_OBJECT *obj)
+{
+    if (obj)
+    {
+        X509_OBJECT_free_contents(obj);
+        OPENSSL_free(obj);
+    }
+}
+#endif
+
+#if !defined(HAVE_X509_OBJECT_GET_TYPE)
+/**
+ * Get the type of an X509 object
+ *
+ * @param obj                X509 object
+ * @return                   The underlying object type
+ */
+static inline int
+X509_OBJECT_get_type(const X509_OBJECT *obj)
+{
+    return obj ? obj->type : X509_LU_FAIL;
+}
+#endif
+
+#if !defined(HAVE_EVP_PKEY_GET0_RSA)
+/**
+ * Get the RSA object of a public key
+ *
+ * @param pkey                Public key object
+ * @return                    The underlying RSA object
+ */
+static inline RSA *
+EVP_PKEY_get0_RSA(EVP_PKEY *pkey)
+{
+    return (pkey && pkey->type == EVP_PKEY_RSA) ? pkey->pkey.rsa : NULL;
+}
+#endif
+
+#if !defined(HAVE_EVP_PKEY_GET0_EC_KEY) && !defined(OPENSSL_NO_EC)
+/**
+ * Get the EC_KEY object of a public key
+ *
+ * @param pkey                Public key object
+ * @return                    The underlying EC_KEY object
+ */
+static inline EC_KEY *
+EVP_PKEY_get0_EC_KEY(EVP_PKEY *pkey)
+{
+    return (pkey && pkey->type == EVP_PKEY_EC) ? pkey->pkey.ec : NULL;
+}
+#endif
+
+#if !defined(HAVE_EVP_PKEY_ID)
+/**
+ * Get the PKEY type
+ *
+ * @param pkey                Public key object
+ * @return                    The key type
+ */
+static inline int
+EVP_PKEY_id(const EVP_PKEY *pkey)
+{
+    return pkey ? pkey->type : EVP_PKEY_NONE;
+}
+#endif
+
+#if !defined(HAVE_EVP_PKEY_GET0_DSA)
+/**
+ * Get the DSA object of a public key
+ *
+ * @param pkey                Public key object
+ * @return                    The underlying DSA object
+ */
+static inline DSA *
+EVP_PKEY_get0_DSA(EVP_PKEY *pkey)
+{
+    return (pkey && pkey->type == EVP_PKEY_DSA) ? pkey->pkey.dsa : NULL;
+}
+#endif
+
+#if !defined(HAVE_RSA_SET_FLAGS)
+/**
+ * Set the RSA flags
+ *
+ * @param rsa                 The RSA object
+ * @param flags               New flags value
+ */
+static inline void
+RSA_set_flags(RSA *rsa, int flags)
+{
+    if (rsa)
+    {
+        rsa->flags = flags;
+    }
+}
+#endif
+
+#if !defined(HAVE_RSA_GET0_KEY)
+/**
+ * Get the RSA parameters
+ *
+ * @param rsa                 The RSA object
+ * @param n                   The @c n parameter
+ * @param e                   The @c e parameter
+ * @param d                   The @c d parameter
+ */
+static inline void
+RSA_get0_key(const RSA *rsa, const BIGNUM **n,
+             const BIGNUM **e, const BIGNUM **d)
+{
+    if (n != NULL)
+    {
+        *n = rsa ? rsa->n : NULL;
+    }
+    if (e != NULL)
+    {
+        *e = rsa ? rsa->e : NULL;
+    }
+    if (d != NULL)
+    {
+        *d = rsa ? rsa->d : NULL;
+    }
+}
+#endif
+
+#if !defined(HAVE_RSA_SET0_KEY)
+/**
+ * Set the RSA parameters
+ *
+ * @param rsa                 The RSA object
+ * @param n                   The @c n parameter
+ * @param e                   The @c e parameter
+ * @param d                   The @c d parameter
+ * @return                    1 on success, 0 on error
+ */
+static inline int
+RSA_set0_key(RSA *rsa, BIGNUM *n, BIGNUM *e, BIGNUM *d)
+{
+    if ((rsa->n == NULL && n == NULL)
+        || (rsa->e == NULL && e == NULL))
+    {
+        return 0;
+    }
+
+    if (n != NULL)
+    {
+        BN_free(rsa->n);
+        rsa->n = n;
+    }
+    if (e != NULL)
+    {
+        BN_free(rsa->e);
+        rsa->e = e;
+    }
+    if (d != NULL)
+    {
+        BN_free(rsa->d);
+        rsa->d = d;
+    }
+
+    return 1;
+}
+#endif
+
+#if !defined(HAVE_RSA_BITS)
+/**
+ * Number of significant RSA bits
+ *
+ * @param rsa                The RSA object ; shall not be NULL
+ * @return                   The number of RSA bits or 0 on error
+ */
+static inline int
+RSA_bits(const RSA *rsa)
+{
+    const BIGNUM *n = NULL;
+    RSA_get0_key(rsa, &n, NULL, NULL);
+    return n ? BN_num_bits(n) : 0;
+}
+#endif
+
+#if !defined(HAVE_DSA_GET0_PQG)
+/**
+ * Get the DSA parameters
+ *
+ * @param dsa                 The DSA object
+ * @param p                   The @c p parameter
+ * @param q                   The @c q parameter
+ * @param g                   The @c g parameter
+ */
+static inline void
+DSA_get0_pqg(const DSA *dsa, const BIGNUM **p,
+             const BIGNUM **q, const BIGNUM **g)
+{
+    if (p != NULL)
+    {
+        *p = dsa ? dsa->p : NULL;
+    }
+    if (q != NULL)
+    {
+        *q = dsa ? dsa->q : NULL;
+    }
+    if (g != NULL)
+    {
+        *g = dsa ? dsa->g : NULL;
+    }
+}
+#endif
+
+#if !defined(HAVE_DSA_BITS)
+/**
+ * Number of significant DSA bits
+ *
+ * @param rsa                The DSA object ; shall not be NULL
+ * @return                   The number of DSA bits or 0 on error
+ */
+static inline int
+DSA_bits(const DSA *dsa)
+{
+    const BIGNUM *p = NULL;
+    DSA_get0_pqg(dsa, &p, NULL, NULL);
+    return p ? BN_num_bits(p) : 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_NEW)
+/**
+ * Allocate a new RSA method object
+ *
+ * @param name               The object name
+ * @param flags              Configuration flags
+ * @return                   A new RSA method object
+ */
+static inline RSA_METHOD *
+RSA_meth_new(const char *name, int flags)
+{
+    RSA_METHOD *rsa_meth = NULL;
+    ALLOC_OBJ_CLEAR(rsa_meth, RSA_METHOD);
+    rsa_meth->name = string_alloc(name, NULL);
+    rsa_meth->flags = flags;
+    return rsa_meth;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_FREE)
+/**
+ * Free an existing RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ */
+static inline void
+RSA_meth_free(RSA_METHOD *meth)
+{
+    if (meth)
+    {
+        /* OpenSSL defines meth->name to be a const pointer, yet we
+         * feed it with an allocated string (from RSA_meth_new()).
+         * Thus we are allowed to free it here. In order to avoid a
+         * "passing 'const char *' to parameter of type 'void *' discards
+         * qualifiers" warning, we force the pointer to be a non-const value.
+         */
+        free((char *)meth->name);
+        free(meth);
+    }
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_PUB_ENC)
+/**
+ * Set the public encoding function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param pub_enc            the public encoding function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_pub_enc(RSA_METHOD *meth,
+                     int (*pub_enc) (int flen, const unsigned char *from,
+                                     unsigned char *to, RSA *rsa,
+                                     int padding))
+{
+    if (meth)
+    {
+        meth->rsa_pub_enc = pub_enc;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_PUB_DEC)
+/**
+ * Set the public decoding function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param pub_dec            the public decoding function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_pub_dec(RSA_METHOD *meth,
+                     int (*pub_dec) (int flen, const unsigned char *from,
+                                     unsigned char *to, RSA *rsa,
+                                     int padding))
+{
+    if (meth)
+    {
+        meth->rsa_pub_dec = pub_dec;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_PRIV_ENC)
+/**
+ * Set the private encoding function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param priv_enc           the private encoding function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_priv_enc(RSA_METHOD *meth,
+                      int (*priv_enc) (int flen, const unsigned char *from,
+                                       unsigned char *to, RSA *rsa,
+                                       int padding))
+{
+    if (meth)
+    {
+        meth->rsa_priv_enc = priv_enc;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_PRIV_DEC)
+/**
+ * Set the private decoding function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param priv_dec           the private decoding function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_priv_dec(RSA_METHOD *meth,
+                      int (*priv_dec) (int flen, const unsigned char *from,
+                                       unsigned char *to, RSA *rsa,
+                                       int padding))
+{
+    if (meth)
+    {
+        meth->rsa_priv_dec = priv_dec;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_INIT)
+/**
+ * Set the init function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param init               the init function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_init(RSA_METHOD *meth, int (*init) (RSA *rsa))
+{
+    if (meth)
+    {
+        meth->init = init;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined (HAVE_RSA_METH_SET_SIGN)
+/**
+ * Set the sign function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param sign               The sign function
+ * @return                   1 on success, 0 on error
+ */
+static inline
+int RSA_meth_set_sign(RSA_METHOD *meth,
+                      int (*sign) (int type, const unsigned char *m,
+                                   unsigned int m_length,
+                                   unsigned char *sigret, unsigned int *siglen,
+                                   const RSA *rsa))
+{
+    meth->rsa_sign = sign;
+    return 1;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET_FINISH)
+/**
+ * Set the finish function of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param finish             the finish function
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set_finish(RSA_METHOD *meth, int (*finish) (RSA *rsa))
+{
+    if (meth)
+    {
+        meth->finish = finish;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_SET0_APP_DATA)
+/**
+ * Set the application data of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @param app_data           Application data
+ * @return                   1 on success, 0 on error
+ */
+static inline int
+RSA_meth_set0_app_data(RSA_METHOD *meth, void *app_data)
+{
+    if (meth)
+    {
+        meth->app_data = app_data;
+        return 1;
+    }
+    return 0;
+}
+#endif
+
+#if !defined(HAVE_RSA_METH_GET0_APP_DATA)
+/**
+ * Get the application data of an RSA_METHOD object
+ *
+ * @param meth               The RSA_METHOD object
+ * @return                   pointer to application data, may be NULL
+ */
+static inline void *
+RSA_meth_get0_app_data(const RSA_METHOD *meth)
+{
+    return meth ? meth->app_data : NULL;
+}
+#endif
+
+#if !defined(HAVE_EC_GROUP_ORDER_BITS) && !defined(OPENSSL_NO_EC)
+/**
+ * Gets the number of bits of the order of an EC_GROUP
+ *
+ *  @param  group               EC_GROUP object
+ *  @return                     number of bits of group order.
+ */
+static inline int
+EC_GROUP_order_bits(const EC_GROUP *group)
+{
+    BIGNUM* order = BN_new();
+    EC_GROUP_get_order(group, order, NULL);
+    int bits = BN_num_bits(order);
+    BN_free(order);
+    return bits;
+}
+#endif
+
+/* SSLeay symbols have been renamed in OpenSSL 1.1 */
+#if !defined(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT)
+#define RSA_F_RSA_OSSL_PRIVATE_ENCRYPT       RSA_F_RSA_EAY_PRIVATE_ENCRYPT
+#endif
+
+#ifndef SSL_CTX_get_min_proto_version
+/** Return the min SSL protocol version currently enabled in the context.
+ *  If no valid version >= TLS1.0 is found, return 0. */
+static inline int
+SSL_CTX_get_min_proto_version(SSL_CTX *ctx)
+{
+    long sslopt = SSL_CTX_get_options(ctx);
+    if (!(sslopt & SSL_OP_NO_TLSv1))
+    {
+        return TLS1_VERSION;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (!(sslopt & SSL_OP_NO_TLSv1_1))
+    {
+        return TLS1_1_VERSION;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (!(sslopt & SSL_OP_NO_TLSv1_2))
+    {
+        return TLS1_2_VERSION;
+    }
+#endif
+    return 0;
+}
+#endif /* SSL_CTX_get_min_proto_version */
+
+#ifndef SSL_CTX_get_max_proto_version
+/** Return the max SSL protocol version currently enabled in the context.
+ *  If no valid version >= TLS1.0 is found, return 0. */
+static inline int
+SSL_CTX_get_max_proto_version(SSL_CTX *ctx)
+{
+    long sslopt = SSL_CTX_get_options(ctx);
+#ifdef SSL_OP_NO_TLSv1_2
+    if (!(sslopt & SSL_OP_NO_TLSv1_2))
+    {
+        return TLS1_2_VERSION;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_1
+    if (!(sslopt & SSL_OP_NO_TLSv1_1))
+    {
+        return TLS1_1_VERSION;
+    }
+#endif
+    if (!(sslopt & SSL_OP_NO_TLSv1))
+    {
+        return TLS1_VERSION;
+    }
+    return 0;
+}
+#endif /* SSL_CTX_get_max_proto_version */
+
+#ifndef SSL_CTX_set_min_proto_version
+/** Mimics SSL_CTX_set_min_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_min_proto_version(SSL_CTX *ctx, long tls_ver_min)
+{
+    long sslopt = SSL_OP_NO_SSLv2 | SSL_OP_NO_SSLv3; /* Never do < TLS 1.0 */
+
+    if (tls_ver_min > TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_min > TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_min > TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_min_proto_version */
+
+#ifndef SSL_CTX_set_max_proto_version
+/** Mimics SSL_CTX_set_max_proto_version for OpenSSL < 1.1 */
+static inline int
+SSL_CTX_set_max_proto_version(SSL_CTX *ctx, long tls_ver_max)
+{
+    long sslopt = 0;
+
+    if (tls_ver_max < TLS1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1;
+    }
+#ifdef SSL_OP_NO_TLSv1_1
+    if (tls_ver_max < TLS1_1_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_1;
+    }
+#endif
+#ifdef SSL_OP_NO_TLSv1_2
+    if (tls_ver_max < TLS1_2_VERSION)
+    {
+        sslopt |= SSL_OP_NO_TLSv1_2;
+    }
+#endif
+    SSL_CTX_set_options(ctx, sslopt);
+
+    return 1;
+}
+#endif /* SSL_CTX_set_max_proto_version */
+
+#endif /* OPENSSL_COMPAT_H_ */
diff --git a/src/openvpn/openvpn.c b/src/openvpn/openvpn.c
new file mode 100644
index 0000000..3d244fc
--- /dev/null
+++ b/src/openvpn/openvpn.c
@@ -0,0 +1,389 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "init.h"
+#include "forward.h"
+#include "multi.h"
+#include "win32.h"
+#include "platform.h"
+
+#include "memdbg.h"
+
+#include "forward-inline.h"
+
+#define P2P_CHECK_SIG() EVENT_LOOP_CHECK_SIGNAL(c, process_signal_p2p, c);
+
+static bool
+process_signal_p2p(struct context *c)
+{
+    remap_signal(c);
+    return process_signal(c);
+}
+
+/* Write our PID to a file */
+static void
+write_pid(const char *filename)
+{
+    if (filename)
+    {
+        unsigned int pid = 0;
+        FILE *fp = platform_fopen(filename, "w");
+        if (!fp)
+        {
+            msg(M_ERR, "Open error on pid file %s", filename);
+        }
+
+        pid = platform_getpid();
+        fprintf(fp, "%u\n", pid);
+        if (fclose(fp))
+        {
+            msg(M_ERR, "Close error on pid file %s", filename);
+        }
+    }
+}
+
+
+/**************************************************************************/
+/**
+ * Main event loop for OpenVPN in client mode, where only one VPN tunnel
+ * is active.
+ * @ingroup eventloop
+ *
+ * @param c - The context structure of the single active VPN tunnel.
+ */
+static void
+tunnel_point_to_point(struct context *c)
+{
+    context_clear_2(c);
+
+    /* set point-to-point mode */
+    c->mode = CM_P2P;
+
+    /* initialize tunnel instance */
+    init_instance_handle_signals(c, c->es, CC_HARD_USR1_TO_HUP);
+    if (IS_SIG(c))
+    {
+        return;
+    }
+
+    /* main event loop */
+    while (true)
+    {
+        perf_push(PERF_EVENT_LOOP);
+
+        /* process timers, TLS, etc. */
+        pre_select(c);
+        P2P_CHECK_SIG();
+
+        /* set up and do the I/O wait */
+        io_wait(c, p2p_iow_flags(c));
+        P2P_CHECK_SIG();
+
+        /* timeout? */
+        if (c->c2.event_set_status == ES_TIMEOUT)
+        {
+            perf_pop();
+            continue;
+        }
+
+        /* process the I/O which triggered select */
+        process_io(c);
+        P2P_CHECK_SIG();
+
+        perf_pop();
+    }
+
+    uninit_management_callback();
+
+    /* tear down tunnel instance (unless --persist-tun) */
+    close_instance(c);
+}
+
+#undef PROCESS_SIGNAL_P2P
+
+
+/**************************************************************************/
+/**
+ * OpenVPN's main init-run-cleanup loop.
+ * @ingroup eventloop
+ *
+ * This function contains the two outer OpenVPN loops.  Its structure is
+ * as follows:
+ *  - Once-per-process initialization.
+ *  - Outer loop, run at startup and then once per \c SIGHUP:
+ *    - Level 1 initialization
+ *    - Inner loop, run at startup and then once per \c SIGUSR1:
+ *      - Call event loop function depending on client or server mode:
+ *        - \c tunnel_point_to_point()
+ *        - \c tunnel_server()
+ *    - Level 1 cleanup
+ *  - Once-per-process cleanup.
+ *
+ * @param argc - Commandline argument count.
+ * @param argv - Commandline argument values.
+ */
+static
+int
+openvpn_main(int argc, char *argv[])
+{
+    struct context c;
+
+#if PEDANTIC
+    fprintf(stderr, "Sorry, I was built with --enable-pedantic and I am incapable of doing any real work!\n");
+    return 1;
+#endif
+
+#ifdef _WIN32
+    SetConsoleOutputCP(CP_UTF8);
+#endif
+
+    CLEAR(c);
+
+    /* signify first time for components which can
+     * only be initialized once per program instantiation. */
+    c.first_time = true;
+
+    /* initialize program-wide statics */
+    if (init_static())
+    {
+        /*
+         * This loop is initially executed on startup and then
+         * once per SIGHUP.
+         */
+        do
+        {
+            /* enter pre-initialization mode with regard to signal handling */
+            pre_init_signal_catch();
+
+            /* zero context struct but leave first_time member alone */
+            context_clear_all_except_first_time(&c);
+
+            /* static signal info object */
+            CLEAR(siginfo_static);
+            c.sig = &siginfo_static;
+
+            /* initialize garbage collector scoped to context object */
+            gc_init(&c.gc);
+
+            /* initialize environmental variable store */
+            c.es = env_set_create(NULL);
+#ifdef _WIN32
+            set_win_sys_path_via_env(c.es);
+#endif
+
+#ifdef ENABLE_MANAGEMENT
+            /* initialize management subsystem */
+            init_management();
+#endif
+
+            /* initialize options to default state */
+            init_options(&c.options, true);
+
+            /* parse command line options, and read configuration file */
+            parse_argv(&c.options, argc, argv, M_USAGE, OPT_P_DEFAULT, NULL, c.es);
+
+#ifdef ENABLE_PLUGIN
+            /* plugins may contribute options configuration */
+            init_verb_mute(&c, IVM_LEVEL_1);
+            init_plugins(&c);
+            open_plugins(&c, true, OPENVPN_PLUGIN_INIT_PRE_CONFIG_PARSE);
+#endif
+
+            /* init verbosity and mute levels */
+            init_verb_mute(&c, IVM_LEVEL_1);
+
+            /* set dev options */
+            init_options_dev(&c.options);
+
+            /* openssl print info? */
+            if (print_openssl_info(&c.options))
+            {
+                break;
+            }
+
+            /* --genkey mode? */
+            if (do_genkey(&c.options))
+            {
+                break;
+            }
+
+            /* tun/tap persist command? */
+            if (do_persist_tuntap(&c.options))
+            {
+                break;
+            }
+
+            /* sanity check on options */
+            options_postprocess(&c.options);
+
+            /* show all option settings */
+            show_settings(&c.options);
+
+            /* print version number */
+            msg(M_INFO, "%s", title_string);
+#ifdef _WIN32
+            show_windows_version(M_INFO);
+#endif
+            show_library_versions(M_INFO);
+
+            /* misc stuff */
+            pre_setup(&c.options);
+
+            /* test crypto? */
+            if (do_test_crypto(&c.options))
+            {
+                break;
+            }
+
+            /* Query passwords before becoming a daemon if we don't use the
+             * management interface to get them. */
+#ifdef ENABLE_MANAGEMENT
+            if (!(c.options.management_flags & MF_QUERY_PASSWORDS))
+#endif
+            init_query_passwords(&c);
+
+            /* become a daemon if --daemon */
+            if (c.first_time)
+            {
+                c.did_we_daemonize = possibly_become_daemon(&c.options);
+                write_pid(c.options.writepid);
+            }
+
+#ifdef ENABLE_MANAGEMENT
+            /* open management subsystem */
+            if (!open_management(&c))
+            {
+                break;
+            }
+            /* query for passwords through management interface, if needed */
+            if (c.options.management_flags & MF_QUERY_PASSWORDS)
+            {
+                init_query_passwords(&c);
+            }
+#endif
+
+            /* set certain options as environmental variables */
+            setenv_settings(c.es, &c.options);
+
+            /* finish context init */
+            context_init_1(&c);
+
+            do
+            {
+                /* run tunnel depending on mode */
+                switch (c.options.mode)
+                {
+                    case MODE_POINT_TO_POINT:
+                        tunnel_point_to_point(&c);
+                        break;
+
+#if P2MP_SERVER
+                    case MODE_SERVER:
+                        tunnel_server(&c);
+                        break;
+
+#endif
+                    default:
+                        ASSERT(0);
+                }
+
+                /* indicates first iteration -- has program-wide scope */
+                c.first_time = false;
+
+                /* any signals received? */
+                if (IS_SIG(&c))
+                {
+                    print_signal(c.sig, NULL, M_INFO);
+                }
+
+                /* pass restart status to management subsystem */
+                signal_restart_status(c.sig);
+            }
+            while (c.sig->signal_received == SIGUSR1);
+
+            env_set_destroy(c.es);
+            uninit_options(&c.options);
+            gc_reset(&c.gc);
+        }
+        while (c.sig->signal_received == SIGHUP);
+    }
+
+    context_gc_free(&c);
+
+#ifdef ENABLE_MANAGEMENT
+    /* close management interface */
+    close_management();
+#endif
+
+    /* uninitialize program-wide statics */
+    uninit_static();
+
+    openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    return 0;                               /* NOTREACHED */
+}
+
+#ifdef _WIN32
+int
+wmain(int argc, wchar_t *wargv[])
+{
+    char **argv;
+    int ret;
+    int i;
+
+    if ((argv = calloc(argc+1, sizeof(char *))) == NULL)
+    {
+        return 1;
+    }
+
+    for (i = 0; i < argc; i++)
+    {
+        int n = WideCharToMultiByte(CP_UTF8, 0, wargv[i], -1, NULL, 0, NULL, NULL);
+        argv[i] = malloc(n);
+        WideCharToMultiByte(CP_UTF8, 0, wargv[i], -1, argv[i], n, NULL, NULL);
+    }
+
+    ret = openvpn_main(argc, argv);
+
+    for (i = 0; i < argc; i++)
+    {
+        free(argv[i]);
+    }
+    free(argv);
+
+    return ret;
+}
+#else  /* ifdef _WIN32 */
+int
+main(int argc, char *argv[])
+{
+    return openvpn_main(argc, argv);
+}
+#endif /* ifdef _WIN32 */
diff --git a/src/openvpn/openvpn.h b/src/openvpn/openvpn.h
new file mode 100644
index 0000000..ed7975c
--- /dev/null
+++ b/src/openvpn/openvpn.h
@@ -0,0 +1,598 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_H
+#define OPENVPN_H
+
+#include "buffer.h"
+#include "options.h"
+#include "socket.h"
+#include "crypto.h"
+#include "ssl.h"
+#include "packet_id.h"
+#include "comp.h"
+#include "tun.h"
+#include "interval.h"
+#include "status.h"
+#include "fragment.h"
+#include "shaper.h"
+#include "route.h"
+#include "proxy.h"
+#include "socks.h"
+#include "sig.h"
+#include "misc.h"
+#include "mbuf.h"
+#include "pool.h"
+#include "plugin.h"
+#include "manage.h"
+#include "pf.h"
+
+/*
+ * Our global key schedules, packaged thusly
+ * to facilitate --persist-key.
+ */
+
+struct key_schedule
+{
+#ifdef ENABLE_CRYPTO
+    /* which cipher, HMAC digest, and key sizes are we using? */
+    struct key_type key_type;
+
+    /* pre-shared static key, read from a file */
+    struct key_ctx_bi static_key;
+
+    /* our global SSL context */
+    struct tls_root_ctx ssl_ctx;
+
+    /* optional TLS control channel wrapping */
+    struct key_type tls_auth_key_type;
+    struct key_ctx_bi tls_wrap_key;
+#else                           /* ENABLE_CRYPTO */
+    int dummy;
+#endif                          /* ENABLE_CRYPTO */
+};
+
+/*
+ * struct packet_id_persist should be empty if we are not
+ * building with crypto.
+ */
+#ifndef PACKET_ID_H
+struct packet_id_persist
+{
+    int dummy;
+};
+static inline void
+packet_id_persist_init(struct packet_id_persist *p)
+{
+}
+#endif
+
+/*
+ * Packet processing buffers.
+ */
+struct context_buffers
+{
+    /* miscellaneous buffer, used by ping, occ, etc. */
+    struct buffer aux_buf;
+
+    /* workspace buffers used by crypto routines */
+#ifdef ENABLE_CRYPTO
+    struct buffer encrypt_buf;
+    struct buffer decrypt_buf;
+#endif
+
+    /* workspace buffers for compression */
+#ifdef USE_COMP
+    struct buffer compress_buf;
+    struct buffer decompress_buf;
+#endif
+
+    /*
+     * Buffers used to read from TUN device
+     * and TCP/UDP port.
+     */
+    struct buffer read_link_buf;
+    struct buffer read_tun_buf;
+};
+
+/*
+ * always-persistent context variables
+ */
+struct context_persist
+{
+    int restart_sleep_seconds;
+};
+
+
+/**************************************************************************/
+/**
+ * Level 0 %context containing information related to the OpenVPN process.
+ *
+ * Level 0 state is initialized once at program startup, and then remains
+ * throughout the lifetime of the OpenVPN process.  This structure
+ * contains information related to the process's PID, user, group, and
+ * privileges.
+ */
+struct context_0
+{
+    /* workspace for --user/--group */
+    bool uid_gid_specified;
+    /* helper which tells us whether we should keep trying to drop privileges */
+    bool uid_gid_chroot_set;
+    struct platform_state_user platform_state_user;
+    struct platform_state_group platform_state_group;
+};
+
+
+/**
+ * Level 1 %context containing state that persists across \c SIGUSR1
+ * restarts.
+ *
+ * Level 1 state is reset on \c SIGHUP restarts.  This structure is
+ * initialized for every iteration of the \c main() function's outer \c
+ * SIGHUP loop, but persists over iteration of that function's inner \c
+ * SIGUSR1 loop.
+ */
+struct context_1
+{
+    struct link_socket_addr link_socket_addr;
+    /**< Local and remote addresses on the
+     *   external network. */
+
+    /* tunnel session keys */
+    struct key_schedule ks;
+
+    /* preresolved and cached host names */
+    struct cached_dns_entry *dns_cache;
+
+    /* persist crypto sequence number to/from file */
+    struct packet_id_persist pid_persist;
+
+    struct tuntap *tuntap;      /**< Tun/tap virtual network interface. */
+    bool tuntap_owned;          /**< Whether the tun/tap interface should
+                                 *   be cleaned up when this %context is
+                                 *   cleaned up. */
+
+    struct route_list *route_list;
+    /**< List of routing information. See the
+     *   \c --route command line option. */
+
+    /* list of --route-ipv6 directives */
+    struct route_ipv6_list *route_ipv6_list;
+
+    /* --status file */
+    struct status_output *status_output;
+    bool status_output_owned;
+
+    /* HTTP proxy object */
+    struct http_proxy_info *http_proxy;
+    bool http_proxy_owned;
+
+    /* SOCKS proxy object */
+    struct socks_proxy_info *socks_proxy;
+    bool socks_proxy_owned;
+
+#if P2MP
+
+#if P2MP_SERVER
+    /* persist --ifconfig-pool db to file */
+    struct ifconfig_pool_persist *ifconfig_pool_persist;
+    bool ifconfig_pool_persist_owned;
+#endif
+
+    /* if client mode, hash of option strings we pulled from server */
+    struct sha256_digest pulled_options_digest_save;
+    /**< Hash of option strings received from the
+     *   remote OpenVPN server.  Only used in
+     *   client-mode. */
+
+    struct user_pass *auth_user_pass;
+    /**< Username and password for
+     *   authentication. */
+
+    const char *ciphername;     /**< Data channel cipher from config file */
+    const char *authname;       /**< Data channel auth from config file */
+    int keysize;                /**< Data channel keysize from config file */
+#endif
+};
+
+/**
+ * Level 2 %context containing state that is reset on both \c SIGHUP and
+ * \c SIGUSR1 restarts.
+ *
+ * This structure is initialized at the top of the \c
+ * tunnel_point_to_point(), \c tunnel_server_udp_single_threaded(), and \c
+ * tunnel_server_tcp() functions.  In other words, it is reset for every
+ * iteration of the \c main() function's inner \c SIGUSR1 loop.
+ */
+struct context_2
+{
+    struct gc_arena gc;         /**< Garbage collection arena for
+                                 *   allocations done in the level 2 scope
+                                 *   of this context_2 structure. */
+
+    /* our global wait events */
+    struct event_set *event_set;
+    int event_set_max;
+    bool event_set_owned;
+
+    /* event flags returned by io_wait */
+#define SOCKET_READ       (1<<0)
+#define SOCKET_WRITE      (1<<1)
+#define TUN_READ          (1<<2)
+#define TUN_WRITE         (1<<3)
+#define ES_ERROR          (1<<4)
+#define ES_TIMEOUT        (1<<5)
+#ifdef ENABLE_MANAGEMENT
+#define MANAGEMENT_READ  (1<<6)
+#define MANAGEMENT_WRITE (1<<7)
+#endif
+#ifdef ENABLE_ASYNC_PUSH
+#define FILE_CLOSED       (1<<8)
+#endif
+
+    unsigned int event_set_status;
+
+    struct link_socket *link_socket;     /* socket used for TCP/UDP connection to remote */
+    bool link_socket_owned;
+    struct link_socket_info *link_socket_info;
+    const struct link_socket *accept_from; /* possibly do accept() on a parent link_socket */
+
+    struct link_socket_actual *to_link_addr;    /* IP address of remote */
+    struct link_socket_actual from;             /* address of incoming datagram */
+
+    /* MTU frame parameters */
+    struct frame frame;                         /* Active frame parameters */
+    struct frame frame_initial;                 /* Restored on new session */
+
+#ifdef ENABLE_FRAGMENT
+    /* Object to handle advanced MTU negotiation and datagram fragmentation */
+    struct fragment_master *fragment;
+    struct frame frame_fragment;
+    struct frame frame_fragment_initial;
+    struct frame frame_fragment_omit;
+#endif
+
+#ifdef ENABLE_FEATURE_SHAPER
+    /*
+     * Traffic shaper object.
+     */
+    struct shaper shaper;
+#endif
+
+    /*
+     * Statistics
+     */
+    counter_type tun_read_bytes;
+    counter_type tun_write_bytes;
+    counter_type link_read_bytes;
+    counter_type link_read_bytes_auth;
+    counter_type link_write_bytes;
+#ifdef PACKET_TRUNCATION_CHECK
+    counter_type n_trunc_tun_read;
+    counter_type n_trunc_tun_write;
+    counter_type n_trunc_pre_encrypt;
+    counter_type n_trunc_post_decrypt;
+#endif
+
+    /*
+     * Timer objects for ping and inactivity
+     * timeout features.
+     */
+    struct event_timeout wait_for_connect;
+    struct event_timeout ping_send_interval;
+    struct event_timeout ping_rec_interval;
+
+    /* --inactive */
+    struct event_timeout inactivity_interval;
+    int inactivity_bytes;
+
+#ifdef ENABLE_OCC
+    /* the option strings must match across peers */
+    char *options_string_local;
+    char *options_string_remote;
+
+    int occ_op;                 /* INIT to -1 */
+    int occ_n_tries;
+    struct event_timeout occ_interval;
+#endif
+
+    /*
+     * Keep track of maximum packet size received so far
+     * (of authenticated packets).
+     */
+    int original_recv_size;     /* temporary */
+    int max_recv_size_local;    /* max packet size received */
+    int max_recv_size_remote;   /* max packet size received by remote */
+    int max_send_size_local;    /* max packet size sent */
+    int max_send_size_remote;   /* max packet size sent by remote */
+
+#ifdef ENABLE_OCC
+    /* remote wants us to send back a load test packet of this size */
+    int occ_mtu_load_size;
+
+    struct event_timeout occ_mtu_load_test_interval;
+    int occ_mtu_load_n_tries;
+#endif
+
+#ifdef ENABLE_CRYPTO
+
+    /*
+     * TLS-mode crypto objects.
+     */
+    struct tls_multi *tls_multi; /**< TLS state structure for this VPN
+                                  *   tunnel. */
+
+    struct tls_auth_standalone *tls_auth_standalone;
+    /**< TLS state structure required for the
+     *   initial authentication of a client's
+     *   connection attempt.  This structure
+     *   is used by the \c
+     *   tls_pre_decrypt_lite() function when
+     *   it performs the HMAC firewall check
+     *   on the first connection packet
+     *   received from a new client.  See the
+     *   \c --tls-auth commandline option. */
+
+    /* used to optimize calls to tls_multi_process */
+    struct interval tmp_int;
+
+    /* throw this signal on TLS errors */
+    int tls_exit_signal;
+
+    struct crypto_options crypto_options;
+    /**< Security parameters and crypto state
+     *   used by the \link data_crypto Data
+     *   Channel Crypto module\endlink to
+     *   process data channel packet. */
+
+    struct event_timeout packet_id_persist_interval;
+
+#endif /* ENABLE_CRYPTO */
+
+#ifdef USE_COMP
+    struct compress_context *comp_context;
+    /**< Compression context used by the
+     *   \link compression Data Channel
+     *   Compression module\endlink. */
+#endif
+
+    /*
+     * Buffers used for packet processing.
+     */
+    struct context_buffers *buffers;
+    bool buffers_owned; /* if true, we should free all buffers on close */
+
+    /*
+     * These buffers don't actually allocate storage, they are used
+     * as pointers to the allocated buffers in
+     * struct context_buffers.
+     */
+    struct buffer buf;
+    struct buffer to_tun;
+    struct buffer to_link;
+
+    /* should we print R|W|r|w to console on packet transfers? */
+    bool log_rw;
+
+    /* route stuff */
+    struct event_timeout route_wakeup;
+    struct event_timeout route_wakeup_expire;
+
+    /* did we open tun/tap dev during this cycle? */
+    bool did_open_tun;
+
+    /*
+     * Event loop info
+     */
+
+    /* how long to wait on link/tun read before we will need to be serviced */
+    struct timeval timeval;
+
+    /* next wakeup for processing coarse timers (>1 sec resolution) */
+    time_t coarse_timer_wakeup;
+
+    /* maintain a random delta to add to timeouts to avoid contexts
+     * waking up simultaneously */
+    time_t update_timeout_random_component;
+    struct timeval timeout_random_component;
+
+    /* Timer for everything up to the first packet from the *OpenVPN* server
+     * socks, http proxy, and tcp packets do not count */
+    struct event_timeout server_poll_interval;
+
+    /* indicates that the do_up_delay function has run */
+    bool do_up_ran;
+
+#ifdef ENABLE_OCC
+    /* indicates that we have received a SIGTERM when
+     * options->explicit_exit_notification is enabled,
+     * but we have not exited yet */
+    time_t explicit_exit_notification_time_wait;
+    struct event_timeout explicit_exit_notification_interval;
+#endif
+
+    /* environmental variables to pass to scripts */
+    struct env_set *es;
+    bool es_owned;
+
+    /* don't wait for TUN/TAP/UDP to be ready to accept write */
+    bool fast_io;
+
+#if P2MP
+
+#if P2MP_SERVER
+    /* --ifconfig endpoints to be pushed to client */
+    bool push_reply_deferred;
+#ifdef ENABLE_ASYNC_PUSH
+    bool push_request_received;
+#endif
+    bool push_ifconfig_defined;
+    time_t sent_push_reply_expiry;
+    in_addr_t push_ifconfig_local;
+    in_addr_t push_ifconfig_remote_netmask;
+    in_addr_t push_ifconfig_local_alias;
+
+    bool push_ifconfig_ipv6_defined;
+    struct in6_addr push_ifconfig_ipv6_local;
+    int push_ifconfig_ipv6_netbits;
+    struct in6_addr push_ifconfig_ipv6_remote;
+
+    /* client authentication state, CAS_SUCCEEDED must be 0 */
+#define CAS_SUCCEEDED 0
+#define CAS_PENDING   1
+#define CAS_FAILED    2
+#define CAS_PARTIAL   3  /* at least one client-connect script/plugin
+                          * succeeded while a later one in the chain failed */
+    int context_auth;
+#endif /* if P2MP_SERVER */
+
+    struct event_timeout push_request_interval;
+    int n_sent_push_requests;
+    bool did_pre_pull_restore;
+
+    /* hash of pulled options, so we can compare when options change */
+    bool pulled_options_digest_init_done;
+    md_ctx_t *pulled_options_state;
+    struct sha256_digest pulled_options_digest;
+
+    struct event_timeout scheduled_exit;
+    int scheduled_exit_signal;
+#endif /* if P2MP */
+
+    /* packet filter */
+#ifdef ENABLE_PF
+    struct pf_context pf;
+#endif
+
+#ifdef MANAGEMENT_DEF_AUTH
+    struct man_def_auth_context mda_context;
+#endif
+
+#ifdef ENABLE_ASYNC_PUSH
+    int inotify_fd; /* descriptor for monitoring file changes */
+#endif
+};
+
+
+/**
+ * Contains all state information for one tunnel.
+ *
+ * This structure represents one VPN tunnel.  It is used to store state
+ * information related to a VPN tunnel, but also includes process-wide
+ * data, such as configuration options.
+ *
+ * The @ref tunnel_state "Structure of VPN tunnel state storage" related
+ * page describes how this structure is used in client-mode and
+ * server-mode.
+ */
+struct context
+{
+    struct options options;     /**< Options loaded from command line or
+                                 *   configuration file. */
+
+    bool first_time;            /**< True on the first iteration of
+                                 *   OpenVPN's main loop. */
+
+    /* context modes */
+#define CM_P2P            0  /* standalone point-to-point session or client */
+#define CM_TOP            1  /* top level of a multi-client or point-to-multipoint server */
+#define CM_TOP_CLONE      2  /* clone of a CM_TOP context for one thread */
+#define CM_CHILD_UDP      3  /* child context of a CM_TOP or CM_THREAD */
+#define CM_CHILD_TCP      4  /* child context of a CM_TOP or CM_THREAD */
+    int mode;                   /**< Role of this context within the
+                                 *   OpenVPN process.  Valid values are \c
+                                 *   CM_P2P, \c CM_TOP, \c CM_TOP_CLONE,
+                                 *   \c CM_CHILD_UDP, and \c CM_CHILD_TCP. */
+
+    struct gc_arena gc;         /**< Garbage collection arena for
+                                 *   allocations done in the scope of this
+                                 *   context structure. */
+
+    struct env_set *es;         /**< Set of environment variables. */
+
+    struct signal_info *sig;    /**< Internal error signaling object. */
+
+    struct plugin_list *plugins; /**< List of plug-ins. */
+    bool plugins_owned;         /**< Whether the plug-ins should be
+                                 *   cleaned up when this %context is
+                                 *   cleaned up. */
+
+    bool did_we_daemonize;      /**< Whether demonization has already
+                                 *   taken place. */
+
+    struct context_persist persist;
+    /**< Persistent %context. */
+    struct context_0 *c0;       /**< Level 0 %context. */
+    struct context_1 c1;        /**< Level 1 %context. */
+    struct context_2 c2;        /**< Level 2 %context. */
+};
+
+/*
+ * Check for a signal when inside an event loop
+ */
+#define EVENT_LOOP_CHECK_SIGNAL(c, func, arg)   \
+    if (IS_SIG(c))                           \
+    {                                       \
+        const int brk = func(arg);           \
+        perf_pop();                          \
+        if (brk) {                              \
+            break;}                              \
+        else {                                  \
+            continue;}                           \
+    }
+
+/*
+ * Macros for referencing objects which may not
+ * have been compiled in.
+ */
+
+#ifdef ENABLE_CRYPTO
+#define TLS_MODE(c) ((c)->c2.tls_multi != NULL)
+#define PROTO_DUMP_FLAGS (check_debug_level(D_LINK_RW_VERBOSE) ? (PD_SHOW_DATA|PD_VERBOSE) : 0)
+#define PROTO_DUMP(buf, gc) protocol_dump((buf), \
+                                          PROTO_DUMP_FLAGS   \
+                                          |(c->c2.tls_multi ? PD_TLS : 0)   \
+                                          |(c->options.tls_auth_file ? c->c1.ks.key_type.hmac_length : 0), \
+                                          gc)
+#else  /* ifdef ENABLE_CRYPTO */
+#define TLS_MODE(c) (false)
+#define PROTO_DUMP(buf, gc) format_hex(BPTR(buf), BLEN(buf), 80, gc)
+#endif
+
+#ifdef ENABLE_CRYPTO
+#define MD5SUM(buf, len, gc) md5sum((buf), (len), 0, (gc))
+#else
+#define MD5SUM(buf, len, gc) "[unavailable]"
+#endif
+
+#ifdef ENABLE_CRYPTO
+#define CIPHER_ENABLED(c) (c->c1.ks.key_type.cipher != NULL)
+#else
+#define CIPHER_ENABLED(c) (false)
+#endif
+
+/* this represents "disabled peer-id" */
+#define MAX_PEER_ID 0xFFFFFF
+
+#endif /* ifndef OPENVPN_H */
diff --git a/src/openvpn/openvpn_win32_resources.rc b/src/openvpn/openvpn_win32_resources.rc
new file mode 100644
index 0000000..e4f1ee9
--- /dev/null
+++ b/src/openvpn/openvpn_win32_resources.rc
@@ -0,0 +1,43 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#else
+#include <config-msvc-version.h>
+#endif
+#include <winresrc.h>
+
+#pragma code_page(65001) /* UTF8 */
+
+LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
+
+VS_VERSION_INFO VERSIONINFO
+ FILEVERSION OPENVPN_VERSION_RESOURCE
+ PRODUCTVERSION OPENVPN_VERSION_RESOURCE
+ FILEFLAGSMASK 0x3fL
+#ifdef _DEBUG
+ FILEFLAGS 0x1L
+#else
+ FILEFLAGS 0x0L
+#endif
+ FILEOS 0x40004L
+ FILETYPE VFT_APP
+ FILESUBTYPE 0x0L
+BEGIN
+    BLOCK "StringFileInfo"
+    BEGIN
+        BLOCK "040904b0"
+        BEGIN
+            VALUE "CompanyName", "The OpenVPN Project"
+            VALUE "FileDescription", "OpenVPN Daemon"
+            VALUE "FileVersion", PACKAGE_VERSION ".0"
+            VALUE "InternalName", "OpenVPN"
+            VALUE "LegalCopyright", "Copyright © The OpenVPN Project" 
+            VALUE "OriginalFilename", "openvpn.exe"
+            VALUE "ProductName", "OpenVPN"
+            VALUE "ProductVersion", PACKAGE_VERSION ".0"
+        END
+    END
+    BLOCK "VarFileInfo"
+    BEGIN
+        VALUE "Translation", 0x409, 1200
+    END
+END
diff --git a/src/openvpn/options.c b/src/openvpn/options.c
new file mode 100644
index 0000000..32e4c95
--- /dev/null
+++ b/src/openvpn/options.c
@@ -0,0 +1,8295 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2008-2013 David Sommerseth <dazo@users.sourceforge.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * 2004-01-28: Added Socks5 proxy support
+ *   (Christof Meerwald, http://cmeerw.org)
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+#ifdef HAVE_CONFIG_VERSION_H
+#include "config-version.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "common.h"
+#include "shaper.h"
+#include "crypto.h"
+#include "ssl.h"
+#include "options.h"
+#include "misc.h"
+#include "socket.h"
+#include "packet_id.h"
+#include "pkcs11.h"
+#include "win32.h"
+#include "push.h"
+#include "pool.h"
+#include "helper.h"
+#include "manage.h"
+#include "forward.h"
+#include "ssl_verify.h"
+#include "platform.h"
+#include <ctype.h>
+
+#include "memdbg.h"
+
+const char title_string[] =
+    PACKAGE_STRING
+#ifdef CONFIGURE_GIT_REVISION
+    " [git:" CONFIGURE_GIT_REVISION CONFIGURE_GIT_FLAGS "]"
+#endif
+    " " TARGET_ALIAS
+#ifdef ENABLE_CRYPTO
+#if defined(ENABLE_CRYPTO_MBEDTLS)
+    " [SSL (mbed TLS)]"
+#elif defined(ENABLE_CRYPTO_OPENSSL)
+    " [SSL (OpenSSL)]"
+#else
+    " [SSL]"
+#endif /* defined(ENABLE_CRYPTO_MBEDTLS) */
+#endif /* ENABLE_CRYPTO */
+#ifdef USE_COMP
+#ifdef ENABLE_LZO
+    " [LZO]"
+#endif
+#ifdef ENABLE_LZ4
+    " [LZ4]"
+#endif
+#ifdef ENABLE_COMP_STUB
+    " [COMP_STUB]"
+#endif
+#endif /* USE_COMP */
+#if EPOLL
+    " [EPOLL]"
+#endif
+#ifdef PRODUCT_TAP_DEBUG
+    " [TAPDBG]"
+#endif
+#ifdef ENABLE_PKCS11
+    " [PKCS11]"
+#endif
+#if ENABLE_IP_PKTINFO
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+    " [MH/PKTINFO]"
+#elif defined(IP_RECVDSTADDR)
+    " [MH/RECVDA]"
+#endif
+#endif
+#ifdef HAVE_AEAD_CIPHER_MODES
+    " [AEAD]"
+#endif
+    " built on " __DATE__
+;
+
+#ifndef ENABLE_SMALL
+
+static const char usage_message[] =
+    "%s\n"
+    "\n"
+    "General Options:\n"
+    "--config file   : Read configuration options from file.\n"
+    "--help          : Show options.\n"
+    "--version       : Show copyright and version information.\n"
+    "\n"
+    "Tunnel Options:\n"
+    "--local host    : Local host name or ip address. Implies --bind.\n"
+    "--remote host [port] : Remote host name or ip address.\n"
+    "--remote-random : If multiple --remote options specified, choose one randomly.\n"
+    "--remote-random-hostname : Add a random string to remote DNS name.\n"
+    "--mode m        : Major mode, m = 'p2p' (default, point-to-point) or 'server'.\n"
+    "--proto p       : Use protocol p for communicating with peer.\n"
+    "                  p = udp (default), tcp-server, or tcp-client\n"
+    "--proto-force p : only consider protocol p in list of connection profiles.\n"
+    "                  p = udp6, tcp6-server, or tcp6-client (ipv6)\n"
+    "--connect-retry n [m] : For client, number of seconds to wait between\n"
+    "                  connection retries (default=%d). On repeated retries\n"
+    "                  the wait time is exponentially increased to a maximum of m\n"
+    "                  (default=%d).\n"
+    "--connect-retry-max n : Maximum connection attempt retries, default infinite.\n"
+    "--http-proxy s p [up] [auth] : Connect to remote host\n"
+    "                  through an HTTP proxy at address s and port p.\n"
+    "                  If proxy authentication is required,\n"
+    "                  up is a file containing username/password on 2 lines, or\n"
+    "                  'stdin' to prompt from console.  Add auth='ntlm' if\n"
+    "                  the proxy requires NTLM authentication.\n"
+    "--http-proxy s p 'auto[-nct]' : Like the above directive, but automatically\n"
+    "                  determine auth method and query for username/password\n"
+    "                  if needed.  auto-nct disables weak proxy auth methods.\n"
+    "--http-proxy-option type [parm] : Set extended HTTP proxy options.\n"
+    "                                  Repeat to set multiple options.\n"
+    "                  VERSION version (default=1.0)\n"
+    "                  AGENT user-agent\n"
+    "--socks-proxy s [p] [up] : Connect to remote host through a Socks5 proxy at\n"
+    "                  address s and port p (default port = 1080).\n"
+    "                  If proxy authentication is required,\n"
+    "                  up is a file containing username/password on 2 lines, or\n"
+    "                  'stdin' to prompt for console.\n"
+    "--socks-proxy-retry : Retry indefinitely on Socks proxy errors.\n"
+    "--resolv-retry n: If hostname resolve fails for --remote, retry\n"
+    "                  resolve for n seconds before failing (disabled by default).\n"
+    "                  Set n=\"infinite\" to retry indefinitely.\n"
+    "--float         : Allow remote to change its IP address/port, such as through\n"
+    "                  DHCP (this is the default if --remote is not used).\n"
+    "--ipchange cmd  : Run command cmd on remote ip address initial\n"
+    "                  setting or change -- execute as: cmd ip-address port#\n"
+    "--port port     : TCP/UDP port # for both local and remote.\n"
+    "--lport port    : TCP/UDP port # for local (default=%s). Implies --bind.\n"
+    "--rport port    : TCP/UDP port # for remote (default=%s).\n"
+    "--bind          : Bind to local address and port. (This is the default unless\n"
+    "                  --proto tcp-client"
+    " or --http-proxy"
+    " or --socks-proxy"
+    " is used).\n"
+    "--nobind        : Do not bind to local address and port.\n"
+    "--dev tunX|tapX : tun/tap device (X can be omitted for dynamic device.\n"
+    "--dev-type dt   : Which device type are we using? (dt = tun or tap) Use\n"
+    "                  this option only if the tun/tap device used with --dev\n"
+    "                  does not begin with \"tun\" or \"tap\".\n"
+    "--dev-node node : Explicitly set the device node rather than using\n"
+    "                  /dev/net/tun, /dev/tun, /dev/tap, etc.\n"
+    "--lladdr hw     : Set the link layer address of the tap device.\n"
+    "--topology t    : Set --dev tun topology: 'net30', 'p2p', or 'subnet'.\n"
+#ifdef ENABLE_IPROUTE
+    "--iproute cmd   : Use this command instead of default " IPROUTE_PATH ".\n"
+#endif
+    "--ifconfig l rn : TUN: configure device to use IP address l as a local\n"
+    "                  endpoint and rn as a remote endpoint.  l & rn should be\n"
+    "                  swapped on the other peer.  l & rn must be private\n"
+    "                  addresses outside of the subnets used by either peer.\n"
+    "                  TAP: configure device to use IP address l as a local\n"
+    "                  endpoint and rn as a subnet mask.\n"
+    "--ifconfig-ipv6 l r : configure device to use IPv6 address l as local\n"
+    "                      endpoint (as a /64) and r as remote endpoint\n"
+    "--ifconfig-noexec : Don't actually execute ifconfig/netsh command, instead\n"
+    "                    pass --ifconfig parms by environment to scripts.\n"
+    "--ifconfig-nowarn : Don't warn if the --ifconfig option on this side of the\n"
+    "                    connection doesn't match the remote side.\n"
+    "--route network [netmask] [gateway] [metric] :\n"
+    "                  Add route to routing table after connection\n"
+    "                  is established.  Multiple routes can be specified.\n"
+    "                  netmask default: 255.255.255.255\n"
+    "                  gateway default: taken from --route-gateway or --ifconfig\n"
+    "                  Specify default by leaving blank or setting to \"nil\".\n"
+    "--route-ipv6 network/bits [gateway] [metric] :\n"
+    "                  Add IPv6 route to routing table after connection\n"
+    "                  is established.  Multiple routes can be specified.\n"
+    "                  gateway default: taken from 'remote' in --ifconfig-ipv6\n"
+    "--route-gateway gw|'dhcp' : Specify a default gateway for use with --route.\n"
+    "--route-metric m : Specify a default metric for use with --route.\n"
+    "--route-delay n [w] : Delay n seconds after connection initiation before\n"
+    "                  adding routes (may be 0).  If not specified, routes will\n"
+    "                  be added immediately after tun/tap open.  On Windows, wait\n"
+    "                  up to w seconds for TUN/TAP adapter to come up.\n"
+    "--route-up cmd  : Run command cmd after routes are added.\n"
+    "--route-pre-down cmd : Run command cmd before routes are removed.\n"
+    "--route-noexec  : Don't add routes automatically.  Instead pass routes to\n"
+    "                  --route-up script using environmental variables.\n"
+    "--route-nopull  : When used with --client or --pull, accept options pushed\n"
+    "                  by server EXCEPT for routes and dhcp options.\n"
+    "--allow-pull-fqdn : Allow client to pull DNS names from server for\n"
+    "                    --ifconfig, --route, and --route-gateway.\n"
+    "--redirect-gateway [flags]: Automatically execute routing\n"
+    "                  commands to redirect all outgoing IP traffic through the\n"
+    "                  VPN.  Add 'local' flag if both " PACKAGE_NAME " servers are directly\n"
+    "                  connected via a common subnet, such as with WiFi.\n"
+    "                  Add 'def1' flag to set default route using using 0.0.0.0/1\n"
+    "                  and 128.0.0.0/1 rather than 0.0.0.0/0.  Add 'bypass-dhcp'\n"
+    "                  flag to add a direct route to DHCP server, bypassing tunnel.\n"
+    "                  Add 'bypass-dns' flag to similarly bypass tunnel for DNS.\n"
+    "--redirect-private [flags]: Like --redirect-gateway, but omit actually changing\n"
+    "                  the default gateway.  Useful when pushing private subnets.\n"
+    "--client-nat snat|dnat network netmask alias : on client add 1-to-1 NAT rule.\n"
+#ifdef ENABLE_PUSH_PEER_INFO
+    "--push-peer-info : (client only) push client info to server.\n"
+#endif
+    "--setenv name value : Set a custom environmental variable to pass to script.\n"
+    "--setenv FORWARD_COMPATIBLE 1 : Relax config file syntax checking to allow\n"
+    "                  directives for future OpenVPN versions to be ignored.\n"
+    "--ignore-unkown-option opt1 opt2 ...: Relax config file syntax. Allow\n"
+    "                  these options to be ignored when unknown\n"
+    "--script-security level: Where level can be:\n"
+    "                  0 -- strictly no calling of external programs\n"
+    "                  1 -- (default) only call built-ins such as ifconfig\n"
+    "                  2 -- allow calling of built-ins and scripts\n"
+    "                  3 -- allow password to be passed to scripts via env\n"
+    "--shaper n      : Restrict output to peer to n bytes per second.\n"
+    "--keepalive n m : Helper option for setting timeouts in server mode.  Send\n"
+    "                  ping once every n seconds, restart if ping not received\n"
+    "                  for m seconds.\n"
+    "--inactive n [bytes] : Exit after n seconds of activity on tun/tap device\n"
+    "                  produces a combined in/out byte count < bytes.\n"
+    "--ping-exit n   : Exit if n seconds pass without reception of remote ping.\n"
+    "--ping-restart n: Restart if n seconds pass without reception of remote ping.\n"
+    "--ping-timer-rem: Run the --ping-exit/--ping-restart timer only if we have a\n"
+    "                  remote address.\n"
+    "--ping n        : Ping remote once every n seconds over TCP/UDP port.\n"
+#if ENABLE_IP_PKTINFO
+    "--multihome     : Configure a multi-homed UDP server.\n"
+#endif
+    "--fast-io       : (experimental) Optimize TUN/TAP/UDP writes.\n"
+    "--remap-usr1 s  : On SIGUSR1 signals, remap signal (s='SIGHUP' or 'SIGTERM').\n"
+    "--persist-tun   : Keep tun/tap device open across SIGUSR1 or --ping-restart.\n"
+    "--persist-remote-ip : Keep remote IP address across SIGUSR1 or --ping-restart.\n"
+    "--persist-local-ip  : Keep local IP address across SIGUSR1 or --ping-restart.\n"
+    "--persist-key   : Don't re-read key files across SIGUSR1 or --ping-restart.\n"
+#if PASSTOS_CAPABILITY
+    "--passtos       : TOS passthrough (applies to IPv4 only).\n"
+#endif
+    "--tun-mtu n     : Take the tun/tap device MTU to be n and derive the\n"
+    "                  TCP/UDP MTU from it (default=%d).\n"
+    "--tun-mtu-extra n : Assume that tun/tap device might return as many\n"
+    "                  as n bytes more than the tun-mtu size on read\n"
+    "                  (default TUN=0 TAP=%d).\n"
+    "--link-mtu n    : Take the TCP/UDP device MTU to be n and derive the tun MTU\n"
+    "                  from it.\n"
+    "--mtu-disc type : Should we do Path MTU discovery on TCP/UDP channel?\n"
+    "                  'no'    -- Never send DF (Don't Fragment) frames\n"
+    "                  'maybe' -- Use per-route hints\n"
+    "                  'yes'   -- Always DF (Don't Fragment)\n"
+#ifdef ENABLE_OCC
+    "--mtu-test      : Empirically measure and report MTU.\n"
+#endif
+#ifdef ENABLE_FRAGMENT
+    "--fragment max  : Enable internal datagram fragmentation so that no UDP\n"
+    "                  datagrams are sent which are larger than max bytes.\n"
+    "                  Adds 4 bytes of overhead per datagram.\n"
+#endif
+    "--mssfix [n]    : Set upper bound on TCP MSS, default = tun-mtu size\n"
+    "                  or --fragment max value, whichever is lower.\n"
+    "--sndbuf size   : Set the TCP/UDP send buffer size.\n"
+    "--rcvbuf size   : Set the TCP/UDP receive buffer size.\n"
+#if defined(TARGET_LINUX) && HAVE_DECL_SO_MARK
+    "--mark value    : Mark encrypted packets being sent with value. The mark value\n"
+    "                  can be matched in policy routing and packetfilter rules.\n"
+#endif
+    "--txqueuelen n  : Set the tun/tap TX queue length to n (Linux only).\n"
+#ifdef ENABLE_MEMSTATS
+    "--memstats file : Write live usage stats to memory mapped binary file.\n"
+#endif
+    "--mlock         : Disable Paging -- ensures key material and tunnel\n"
+    "                  data will never be written to disk.\n"
+    "--up cmd        : Run command cmd after successful tun device open.\n"
+    "                  Execute as: cmd tun/tap-dev tun-mtu link-mtu \\\n"
+    "                              ifconfig-local-ip ifconfig-remote-ip\n"
+    "                  (pre --user or --group UID/GID change)\n"
+    "--up-delay      : Delay tun/tap open and possible --up script execution\n"
+    "                  until after TCP/UDP connection establishment with peer.\n"
+    "--down cmd      : Run command cmd after tun device close.\n"
+    "                  (post --user/--group UID/GID change and/or --chroot)\n"
+    "                  (command parameters are same as --up option)\n"
+    "--down-pre      : Run --down command before TUN/TAP close.\n"
+    "--up-restart    : Run up/down commands for all restarts including those\n"
+    "                  caused by --ping-restart or SIGUSR1\n"
+    "--user user     : Set UID to user after initialization.\n"
+    "--group group   : Set GID to group after initialization.\n"
+    "--chroot dir    : Chroot to this directory after initialization.\n"
+#ifdef ENABLE_SELINUX
+    "--setcon context: Apply this SELinux context after initialization.\n"
+#endif
+    "--cd dir        : Change to this directory before initialization.\n"
+    "--daemon [name] : Become a daemon after initialization.\n"
+    "                  The optional 'name' parameter will be passed\n"
+    "                  as the program name to the system logger.\n"
+    "--syslog [name] : Output to syslog, but do not become a daemon.\n"
+    "                  See --daemon above for a description of the 'name' parm.\n"
+    "--inetd [name] ['wait'|'nowait'] : Run as an inetd or xinetd server.\n"
+    "                  See --daemon above for a description of the 'name' parm.\n"
+    "--log file      : Output log to file which is created/truncated on open.\n"
+    "--log-append file : Append log to file, or create file if nonexistent.\n"
+    "--suppress-timestamps : Don't log timestamps to stdout/stderr.\n"
+    "--machine-readable-output : Always log timestamp, message flags to stdout/stderr.\n"
+    "--writepid file : Write main process ID to file.\n"
+    "--nice n        : Change process priority (>0 = lower, <0 = higher).\n"
+    "--echo [parms ...] : Echo parameters to log output.\n"
+    "--verb n        : Set output verbosity to n (default=%d):\n"
+    "                  (Level 3 is recommended if you want a good summary\n"
+    "                  of what's happening without being swamped by output).\n"
+    "                : 0 -- no output except fatal errors\n"
+    "                : 1 -- startup info + connection initiated messages +\n"
+    "                       non-fatal encryption & net errors\n"
+    "                : 2,3 -- show TLS negotiations & route info\n"
+    "                : 4 -- show parameters\n"
+    "                : 5 -- show 'RrWw' chars on console for each packet sent\n"
+    "                       and received from TCP/UDP (caps) or tun/tap (lc)\n"
+    "                : 6 to 11 -- debug messages of increasing verbosity\n"
+    "--mute n        : Log at most n consecutive messages in the same category.\n"
+    "--status file n : Write operational status to file every n seconds.\n"
+    "--status-version [n] : Choose the status file format version number.\n"
+    "                  Currently, n can be 1, 2, or 3 (default=1).\n"
+#ifdef ENABLE_OCC
+    "--disable-occ   : Disable options consistency check between peers.\n"
+#endif
+#ifdef ENABLE_DEBUG
+    "--gremlin mask  : Special stress testing mode (for debugging only).\n"
+#endif
+#if defined(USE_COMP)
+    "--compress alg  : Use compression algorithm alg\n"
+#if defined(ENABLE_LZO)
+    "--comp-lzo      : Use LZO compression -- may add up to 1 byte per\n"
+    "                  packet for uncompressible data.\n"
+    "--comp-noadapt  : Don't use adaptive compression when --comp-lzo\n"
+    "                  is specified.\n"
+#endif
+#endif
+#ifdef ENABLE_MANAGEMENT
+    "--management ip port [pass] : Enable a TCP server on ip:port to handle\n"
+    "                  management functions.  pass is a password file\n"
+    "                  or 'stdin' to prompt from console.\n"
+#if UNIX_SOCK_SUPPORT
+    "                  To listen on a unix domain socket, specific the pathname\n"
+    "                  in place of ip and use 'unix' as the port number.\n"
+#endif
+    "--management-client : Management interface will connect as a TCP client to\n"
+    "                      ip/port rather than listen as a TCP server.\n"
+    "--management-query-passwords : Query management channel for private key\n"
+    "                  and auth-user-pass passwords.\n"
+    "--management-query-proxy : Query management channel for proxy information.\n"
+    "--management-query-remote : Query management channel for --remote directive.\n"
+    "--management-hold : Start " PACKAGE_NAME " in a hibernating state, until a client\n"
+    "                    of the management interface explicitly starts it.\n"
+    "--management-signal : Issue SIGUSR1 when management disconnect event occurs.\n"
+    "--management-forget-disconnect : Forget passwords when management disconnect\n"
+    "                                 event occurs.\n"
+    "--management-up-down : Report tunnel up/down events to management interface.\n"
+    "--management-log-cache n : Cache n lines of log file history for usage\n"
+    "                  by the management channel.\n"
+#if UNIX_SOCK_SUPPORT
+    "--management-client-user u  : When management interface is a unix socket, only\n"
+    "                              allow connections from user u.\n"
+    "--management-client-group g : When management interface is a unix socket, only\n"
+    "                              allow connections from group g.\n"
+#endif
+#ifdef MANAGEMENT_DEF_AUTH
+    "--management-client-auth : gives management interface client the responsibility\n"
+    "                           to authenticate clients after their client certificate\n"
+    "			      has been verified.\n"
+#endif
+#ifdef MANAGEMENT_PF
+    "--management-client-pf : management interface clients must specify a packet\n"
+    "                         filter file for each connecting client.\n"
+#endif
+#endif /* ifdef ENABLE_MANAGEMENT */
+#ifdef ENABLE_PLUGIN
+    "--plugin m [str]: Load plug-in module m passing str as an argument\n"
+    "                  to its initialization function.\n"
+#endif
+#if P2MP
+#if P2MP_SERVER
+    "\n"
+    "Multi-Client Server options (when --mode server is used):\n"
+    "--server network netmask : Helper option to easily configure server mode.\n"
+    "--server-ipv6 network/bits : Configure IPv6 server mode.\n"
+    "--server-bridge [IP netmask pool-start-IP pool-end-IP] : Helper option to\n"
+    "                    easily configure ethernet bridging server mode.\n"
+    "--push \"option\" : Push a config file option back to the peer for remote\n"
+    "                  execution.  Peer must specify --pull in its config file.\n"
+    "--push-reset    : Don't inherit global push list for specific\n"
+    "                  client instance.\n"
+    "--ifconfig-pool start-IP end-IP [netmask] : Set aside a pool of subnets\n"
+    "                  to be dynamically allocated to connecting clients.\n"
+    "--ifconfig-pool-linear : (DEPRECATED) Use individual addresses rather \n"
+    "                  than /30 subnets\n in tun mode.  Not compatible with\n"
+    "                  Windows clients.\n"
+    "--ifconfig-pool-persist file [seconds] : Persist/unpersist ifconfig-pool\n"
+    "                  data to file, at seconds intervals (default=600).\n"
+    "                  If seconds=0, file will be treated as read-only.\n"
+    "--ifconfig-ipv6-pool base-IP/bits : set aside an IPv6 network block\n"
+    "                  to be dynamically allocated to connecting clients.\n"
+    "--ifconfig-push local remote-netmask : Push an ifconfig option to remote,\n"
+    "                  overrides --ifconfig-pool dynamic allocation.\n"
+    "                  Only valid in a client-specific config file.\n"
+    "--ifconfig-ipv6-push local/bits remote : Push an ifconfig-ipv6 option to\n"
+    "                  remote, overrides --ifconfig-ipv6-pool allocation.\n"
+    "                  Only valid in a client-specific config file.\n"
+    "--iroute network [netmask] : Route subnet to client.\n"
+    "--iroute-ipv6 network/bits : Route IPv6 subnet to client.\n"
+    "                  Sets up internal routes only.\n"
+    "                  Only valid in a client-specific config file.\n"
+    "--disable       : Client is disabled.\n"
+    "                  Only valid in a client-specific config file.\n"
+    "--client-cert-not-required : (DEPRECATED) Don't require client certificate, client\n"
+    "                  will authenticate using username/password.\n"
+    "--verify-client-cert [none|optional|require] : perform no, optional or\n"
+    "                  mandatory client certificate verification.\n"
+    "                  Default is to require the client to supply a certificate.\n"
+    "--username-as-common-name  : For auth-user-pass authentication, use\n"
+    "                  the authenticated username as the common name,\n"
+    "                  rather than the common name from the client cert.\n"
+    "--auth-user-pass-verify cmd method: Query client for username/password and\n"
+    "                  run command cmd to verify.  If method='via-env', pass\n"
+    "                  user/pass via environment, if method='via-file', pass\n"
+    "                  user/pass via temporary file.\n"
+    "--auth-gen-token  [lifetime] Generate a random authentication token which is pushed\n"
+    "                  to each client, replacing the password.  Usefull when\n"
+    "                  OTP based two-factor auth mechanisms are in use and\n"
+    "                  --reneg-* options are enabled. Optionally a lifetime in seconds\n"
+    "                  for generated tokens can be set.\n"
+    "--opt-verify    : Clients that connect with options that are incompatible\n"
+    "                  with those of the server will be disconnected.\n"
+    "--auth-user-pass-optional : Allow connections by clients that don't\n"
+    "                  specify a username/password.\n"
+    "--no-name-remapping : (DEPRECATED) Allow Common Name and X509 Subject to include\n"
+    "                      any printable character.\n"
+    "--client-to-client : Internally route client-to-client traffic.\n"
+    "--duplicate-cn  : Allow multiple clients with the same common name to\n"
+    "                  concurrently connect.\n"
+    "--client-connect cmd : Run command cmd on client connection.\n"
+    "--client-disconnect cmd : Run command cmd on client disconnection.\n"
+    "--client-config-dir dir : Directory for custom client config files.\n"
+    "--ccd-exclusive : Refuse connection unless custom client config is found.\n"
+    "--tmp-dir dir   : Temporary directory, used for --client-connect return file and plugin communication.\n"
+    "--hash-size r v : Set the size of the real address hash table to r and the\n"
+    "                  virtual address table to v.\n"
+    "--bcast-buffers n : Allocate n broadcast buffers.\n"
+    "--tcp-queue-limit n : Maximum number of queued TCP output packets.\n"
+    "--tcp-nodelay   : Macro that sets TCP_NODELAY socket flag on the server\n"
+    "                  as well as pushes it to connecting clients.\n"
+    "--learn-address cmd : Run command cmd to validate client virtual addresses.\n"
+    "--connect-freq n s : Allow a maximum of n new connections per s seconds.\n"
+    "--max-clients n : Allow a maximum of n simultaneously connected clients.\n"
+    "--max-routes-per-client n : Allow a maximum of n internal routes per client.\n"
+    "--stale-routes-check n [t] : Remove routes with a last activity timestamp\n"
+    "                             older than n seconds. Run this check every t\n"
+    "                             seconds (defaults to n).\n"
+    "--explicit-exit-notify [n] : In UDP server mode send [RESTART] command on exit/restart to connected\n"
+    "                             clients. n = 1 - reconnect to same server,\n"
+    "                             2 - advance to next server, default=1.\n"
+#if PORT_SHARE
+    "--port-share host port [dir] : When run in TCP mode, proxy incoming HTTPS\n"
+    "                  sessions to a web server at host:port.  dir specifies an\n"
+    "                  optional directory to write origin IP:port data.\n"
+#endif
+#endif /* if P2MP_SERVER */
+    "\n"
+    "Client options (when connecting to a multi-client server):\n"
+    "--client         : Helper option to easily configure client mode.\n"
+    "--auth-user-pass [up] : Authenticate with server using username/password.\n"
+    "                  up is a file containing the username on the first line,\n"
+    "                  and a password on the second. If either the password or both\n"
+    "                  the username and the password are omitted OpenVPN will prompt\n"
+    "                  for them from console.\n"
+    "--pull           : Accept certain config file options from the peer as if they\n"
+    "                  were part of the local config file.  Must be specified\n"
+    "                  when connecting to a '--mode server' remote host.\n"
+    "--pull-filter accept|ignore|reject t : Filter each option received from the\n"
+    "                  server if it starts with the text t. The action flag accept,\n"
+    "                  ignore or reject causes the option to be allowed, removed or\n"
+    "                  rejected with error. May be specified multiple times, and\n"
+    "                  each filter is applied in the order of appearance.\n"
+    "--auth-retry t  : How to handle auth failures.  Set t to\n"
+    "                  none (default), interact, or nointeract.\n"
+    "--static-challenge t e : Enable static challenge/response protocol using\n"
+    "                  challenge text t, with e indicating echo flag (0|1)\n"
+    "--connect-timeout n : when polling possible remote servers to connect to\n"
+    "                  in a round-robin fashion, spend no more than n seconds\n"
+    "                  waiting for a response before trying the next server.\n"
+    "--allow-recursive-routing : When this option is set, OpenVPN will not drop\n"
+    "                  incoming tun packets with same destination as host.\n"
+#endif /* if P2MP */
+#ifdef ENABLE_OCC
+    "--explicit-exit-notify [n] : On exit/restart, send exit signal to\n"
+    "                  server/remote. n = # of retries, default=1.\n"
+#endif
+#ifdef ENABLE_CRYPTO
+    "\n"
+    "Data Channel Encryption Options (must be compatible between peers):\n"
+    "(These options are meaningful for both Static Key & TLS-mode)\n"
+    "--secret f [d]  : Enable Static Key encryption mode (non-TLS).\n"
+    "                  Use shared secret file f, generate with --genkey.\n"
+    "                  The optional d parameter controls key directionality.\n"
+    "                  If d is specified, use separate keys for each\n"
+    "                  direction, set d=0 on one side of the connection,\n"
+    "                  and d=1 on the other side.\n"
+    "--auth alg      : Authenticate packets with HMAC using message\n"
+    "                  digest algorithm alg (default=%s).\n"
+    "                  (usually adds 16 or 20 bytes per packet)\n"
+    "                  Set alg=none to disable authentication.\n"
+    "--cipher alg    : Encrypt packets with cipher algorithm alg\n"
+    "                  (default=%s).\n"
+    "                  Set alg=none to disable encryption.\n"
+    "--ncp-ciphers list : List of ciphers that are allowed to be negotiated.\n"
+    "--ncp-disable   : Disable cipher negotiation.\n"
+    "--prng alg [nsl] : For PRNG, use digest algorithm alg, and\n"
+    "                   nonce_secret_len=nsl.  Set alg=none to disable PRNG.\n"
+#ifdef HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH
+    "--keysize n     : (DEPRECATED) Size of cipher key in bits (optional).\n"
+    "                  If unspecified, defaults to cipher-specific default.\n"
+#endif
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    "--engine [name] : Enable OpenSSL hardware crypto engine functionality.\n"
+#endif
+    "--no-replay     : (DEPRECATED) Disable replay protection.\n"
+    "--mute-replay-warnings : Silence the output of replay warnings to log file.\n"
+    "--replay-window n [t]  : Use a replay protection sliding window of size n\n"
+    "                         and a time window of t seconds.\n"
+    "                         Default n=%d t=%d\n"
+    "--no-iv         : Disable cipher IV -- only allowed with CBC mode ciphers.\n"
+    "--replay-persist file : Persist replay-protection state across sessions\n"
+    "                  using file.\n"
+    "--test-crypto   : Run a self-test of crypto features enabled.\n"
+    "                  For debugging only.\n"
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    "--use-prediction-resistance: Enable prediction resistance on the random\n"
+    "                             number generator.\n"
+#endif
+    "\n"
+    "TLS Key Negotiation Options:\n"
+    "(These options are meaningful only for TLS-mode)\n"
+    "--tls-server    : Enable TLS and assume server role during TLS handshake.\n"
+    "--tls-client    : Enable TLS and assume client role during TLS handshake.\n"
+    "--key-method m  : (DEPRECATED) Data channel key exchange method.  m should be a method\n"
+    "                  number, such as 1 (default), 2, etc.\n"
+    "--ca file       : Certificate authority file in .pem format containing\n"
+    "                  root certificate.\n"
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    "--capath dir    : A directory of trusted certificates (CAs"
+    " and CRLs).\n"
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+    "--dh file       : File containing Diffie Hellman parameters\n"
+    "                  in .pem format (for --tls-server only).\n"
+    "                  Use \"openssl dhparam -out dh1024.pem 1024\" to generate.\n"
+    "--cert file     : Local certificate in .pem format -- must be signed\n"
+    "                  by a Certificate Authority in --ca file.\n"
+    "--extra-certs file : one or more PEM certs that complete the cert chain.\n"
+    "--key file      : Local private key in .pem format.\n"
+    "--tls-version-min <version> ['or-highest'] : sets the minimum TLS version we\n"
+    "    will accept from the peer.  If version is unrecognized and 'or-highest'\n"
+    "    is specified, require max TLS version supported by SSL implementation.\n"
+    "--tls-version-max <version> : sets the maximum TLS version we will use.\n"
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    "--pkcs12 file   : PKCS#12 file containing local private key, local certificate\n"
+    "                  and optionally the root CA certificate.\n"
+#endif
+#ifdef ENABLE_X509ALTUSERNAME
+    "--x509-username-field : Field in x509 certificate containing the username.\n"
+    "                        Default is CN in the Subject field.\n"
+#endif
+    "--verify-hash hash [algo] : Specify fingerprint for level-1 certificate.\n"
+    "                            Valid algo flags are SHA1 and SHA256. \n"
+#ifdef _WIN32
+    "--cryptoapicert select-string : Load the certificate and private key from the\n"
+    "                  Windows Certificate System Store.\n"
+#endif
+    "--tls-cipher l  : A list l of allowable TLS ciphers separated by : (optional).\n"
+    "                : Use --show-tls to see a list of supported TLS ciphers.\n"
+    "--tls-cert-profile p : Set the allowed certificate crypto algorithm profile\n"
+    "                  (default=legacy).\n"
+    "--tls-timeout n : Packet retransmit timeout on TLS control channel\n"
+    "                  if no ACK from remote within n seconds (default=%d).\n"
+    "--reneg-bytes n : Renegotiate data chan. key after n bytes sent and recvd.\n"
+    "--reneg-pkts n  : Renegotiate data chan. key after n packets sent and recvd.\n"
+    "--reneg-sec n   : Renegotiate data chan. key after n seconds (default=%d).\n"
+    "--hand-window n : Data channel key exchange must finalize within n seconds\n"
+    "                  of handshake initiation by any peer (default=%d).\n"
+    "--tran-window n : Transition window -- old key can live this many seconds\n"
+    "                  after new key renegotiation begins (default=%d).\n"
+    "--single-session: Allow only one session (reset state on restart).\n"
+    "--tls-exit      : Exit on TLS negotiation failure.\n"
+    "--tls-auth f [d]: Add an additional layer of authentication on top of the TLS\n"
+    "                  control channel to protect against attacks on the TLS stack\n"
+    "                  and DoS attacks.\n"
+    "                  f (required) is a shared-secret key file.\n"
+    "                  The optional d parameter controls key directionality,\n"
+    "                  see --secret option for more info.\n"
+    "--tls-crypt key : Add an additional layer of authenticated encryption on top\n"
+    "                  of the TLS control channel to hide the TLS certificate,\n"
+    "                  provide basic post-quantum security and protect against\n"
+    "                  attacks on the TLS stack and DoS attacks.\n"
+    "                  key (required) provides the pre-shared key file.\n"
+    "                  see --secret option for more info.\n"
+    "--askpass [file]: Get PEM password from controlling tty before we daemonize.\n"
+    "--auth-nocache  : Don't cache --askpass or --auth-user-pass passwords.\n"
+    "--crl-verify crl ['dir']: Check peer certificate against a CRL.\n"
+    "--tls-verify cmd: Run command cmd to verify the X509 name of a\n"
+    "                  pending TLS connection that has otherwise passed all other\n"
+    "                  tests of certification.  cmd should return 0 to allow\n"
+    "                  TLS handshake to proceed, or 1 to fail.  (cmd is\n"
+    "                  executed as 'cmd certificate_depth subject')\n"
+    "--tls-export-cert [directory] : Get peer cert in PEM format and store it \n"
+    "                  in an openvpn temporary file in [directory]. Peer cert is \n"
+    "                  stored before tls-verify script execution and deleted after.\n"
+    "--verify-x509-name name: Accept connections only from a host with X509 subject\n"
+    "                  DN name. The remote host must also pass all other tests\n"
+    "                  of verification.\n"
+    "--ns-cert-type t: (DEPRECATED) Require that peer certificate was signed with \n"
+    "                  an explicit nsCertType designation t = 'client' | 'server'.\n"
+    "--x509-track x  : Save peer X509 attribute x in environment for use by\n"
+    "                  plugins and management interface.\n"
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10001000
+    "--keying-material-exporter label len : Save Exported Keying Material (RFC5705)\n"
+    "                  of len bytes (min. 16 bytes) using label in environment for use by plugins.\n"
+#endif
+    "--remote-cert-ku v ... : Require that the peer certificate was signed with\n"
+    "                  explicit key usage, you can specify more than one value.\n"
+    "                  value should be given in hex format.\n"
+    "--remote-cert-eku oid : Require that the peer certificate was signed with\n"
+    "                  explicit extended key usage. Extended key usage can be encoded\n"
+    "                  as an object identifier or OpenSSL string representation.\n"
+    "--remote-cert-tls t: Require that peer certificate was signed with explicit\n"
+    "                  key usage and extended key usage based on RFC3280 TLS rules.\n"
+    "                  t = 'client' | 'server'.\n"
+#ifdef ENABLE_PKCS11
+    "\n"
+    "PKCS#11 Options:\n"
+    "--pkcs11-providers provider ... : PKCS#11 provider to load.\n"
+    "--pkcs11-protected-authentication [0|1] ... : Use PKCS#11 protected authentication\n"
+    "                              path. Set for each provider.\n"
+    "--pkcs11-private-mode hex ...   : PKCS#11 private key mode mask.\n"
+    "                              0       : Try  to determind automatically (default).\n"
+    "                              1       : Use Sign.\n"
+    "                              2       : Use SignRecover.\n"
+    "                              4       : Use Decrypt.\n"
+    "                              8       : Use Unwrap.\n"
+    "--pkcs11-cert-private [0|1] ... : Set if login should be performed before\n"
+    "                                  certificate can be accessed. Set for each provider.\n"
+    "--pkcs11-pin-cache seconds      : Number of seconds to cache PIN. The default is -1\n"
+    "                                  cache until token is removed.\n"
+    "--pkcs11-id-management          : Acquire identity from management interface.\n"
+    "--pkcs11-id serialized-id 'id'  : Identity to use, get using standalone --show-pkcs11-ids\n"
+#endif                  /* ENABLE_PKCS11 */
+    "\n"
+    "SSL Library information:\n"
+    "--show-ciphers  : Show cipher algorithms to use with --cipher option.\n"
+    "--show-digests  : Show message digest algorithms to use with --auth option.\n"
+    "--show-engines  : Show hardware crypto accelerator engines (if available).\n"
+    "--show-tls      : Show all TLS ciphers (TLS used only as a control channel).\n"
+#ifdef _WIN32
+    "\n"
+    "Windows Specific:\n"
+    "--win-sys path    : Pathname of Windows system directory. Default is the pathname\n"
+    "                    from SystemRoot environment variable.\n"
+    "--ip-win32 method : When using --ifconfig on Windows, set TAP-Windows adapter\n"
+    "                    IP address using method = manual, netsh, ipapi,\n"
+    "                    dynamic, or adaptive (default = adaptive).\n"
+    "                    Dynamic method allows two optional parameters:\n"
+    "                    offset: DHCP server address offset (> -256 and < 256).\n"
+    "                            If 0, use network address, if >0, take nth\n"
+    "                            address forward from network address, if <0,\n"
+    "                            take nth address backward from broadcast\n"
+    "                            address.\n"
+    "                            Default is 0.\n"
+    "                    lease-time: Lease time in seconds.\n"
+    "                                Default is one year.\n"
+    "--route-method    : Which method to use for adding routes on Windows?\n"
+    "                    adaptive (default) -- Try ipapi then fall back to exe.\n"
+    "                    ipapi -- Use IP helper API.\n"
+    "                    exe -- Call the route.exe shell command.\n"
+    "--dhcp-option type [parm] : Set extended TAP-Windows properties, must\n"
+    "                    be used with --ip-win32 dynamic.  For options\n"
+    "                    which allow multiple addresses,\n"
+    "                    --dhcp-option must be repeated.\n"
+    "                    DOMAIN name : Set DNS suffix\n"
+    "                    DNS addr    : Set domain name server address(es) (IPv4 and IPv6)\n"
+    "                    NTP         : Set NTP server address(es)\n"
+    "                    NBDD        : Set NBDD server address(es)\n"
+    "                    WINS addr   : Set WINS server address(es)\n"
+    "                    NBT type    : Set NetBIOS over TCP/IP Node type\n"
+    "                                  1: B, 2: P, 4: M, 8: H\n"
+    "                    NBS id      : Set NetBIOS scope ID\n"
+    "                    DISABLE-NBT : Disable Netbios-over-TCP/IP.\n"
+    "--dhcp-renew       : Ask Windows to renew the TAP adapter lease on startup.\n"
+    "--dhcp-pre-release : Ask Windows to release the previous TAP adapter lease on\n"
+    "                       startup.\n"
+    "--register-dns  : Run ipconfig /flushdns and ipconfig /registerdns\n"
+    "                  on connection initiation.\n"
+    "--tap-sleep n   : Sleep for n seconds after TAP adapter open before\n"
+    "                  attempting to set adapter properties.\n"
+    "--pause-exit         : When run from a console window, pause before exiting.\n"
+    "--service ex [0|1]   : For use when " PACKAGE_NAME " is being instantiated by a\n"
+    "                       service, and should not be used directly by end-users.\n"
+    "                       ex is the name of an event object which, when\n"
+    "                       signaled, will cause " PACKAGE_NAME " to exit.  A second\n"
+    "                       optional parameter controls the initial state of ex.\n"
+    "--show-net-up   : Show " PACKAGE_NAME "'s view of routing table and net adapter list\n"
+    "                  after TAP adapter is up and routes have been added.\n"
+#ifdef _WIN32
+    "--block-outside-dns   : Block DNS on other network adapters to prevent DNS leaks\n"
+#endif
+    "Windows Standalone Options:\n"
+    "\n"
+    "--show-adapters : Show all TAP-Windows adapters.\n"
+    "--show-net      : Show " PACKAGE_NAME "'s view of routing table and net adapter list.\n"
+    "--show-valid-subnets : Show valid subnets for --dev tun emulation.\n"
+    "--allow-nonadmin [TAP-adapter] : Allow " PACKAGE_NAME " running without admin privileges\n"
+    "                                 to access TAP adapter.\n"
+#endif /* ifdef _WIN32 */
+    "\n"
+    "Generate a random key (only for non-TLS static key encryption mode):\n"
+    "--genkey        : Generate a random key to be used as a shared secret,\n"
+    "                  for use with the --secret option.\n"
+    "--secret file   : Write key to file.\n"
+#endif                          /* ENABLE_CRYPTO */
+#ifdef ENABLE_FEATURE_TUN_PERSIST
+    "\n"
+    "Tun/tap config mode (available with linux 2.4+):\n"
+    "--mktun         : Create a persistent tunnel.\n"
+    "--rmtun         : Remove a persistent tunnel.\n"
+    "--dev tunX|tapX : tun/tap device\n"
+    "--dev-type dt   : Device type.  See tunnel options above for details.\n"
+    "--user user     : User to set privilege to.\n"
+    "--group group   : Group to set privilege to.\n"
+#endif
+#ifdef ENABLE_PKCS11
+    "\n"
+    "PKCS#11 standalone options:\n"
+#ifdef DEFAULT_PKCS11_MODULE
+    "--show-pkcs11-ids [provider] [cert_private] : Show PKCS#11 available ids.\n"
+#else
+    "--show-pkcs11-ids provider [cert_private] : Show PKCS#11 available ids.\n"
+#endif
+    "                                            --verb option can be added *BEFORE* this.\n"
+#endif                          /* ENABLE_PKCS11 */
+    "\n"
+    "General Standalone Options:\n"
+#ifdef ENABLE_DEBUG
+    "--show-gateway : Show info about default gateway.\n"
+#endif
+;
+
+#endif /* !ENABLE_SMALL */
+
+/*
+ * This is where the options defaults go.
+ * Any option not explicitly set here
+ * will be set to 0.
+ */
+void
+init_options(struct options *o, const bool init_gc)
+{
+    CLEAR(*o);
+    if (init_gc)
+    {
+        gc_init(&o->gc);
+        o->gc_owned = true;
+    }
+    o->mode = MODE_POINT_TO_POINT;
+    o->topology = TOP_NET30;
+    o->ce.proto = PROTO_UDP;
+    o->ce.af = AF_UNSPEC;
+    o->ce.bind_ipv6_only = false;
+    o->ce.connect_retry_seconds = 5;
+    o->ce.connect_retry_seconds_max = 300;
+    o->ce.connect_timeout = 120;
+    o->connect_retry_max = 0;
+    o->ce.local_port = o->ce.remote_port = OPENVPN_PORT;
+    o->verbosity = 1;
+    o->status_file_update_freq = 60;
+    o->status_file_version = 1;
+    o->ce.bind_local = true;
+    o->ce.tun_mtu = TUN_MTU_DEFAULT;
+    o->ce.link_mtu = LINK_MTU_DEFAULT;
+    o->ce.mtu_discover_type = -1;
+    o->ce.mssfix = MSSFIX_DEFAULT;
+    o->route_delay_window = 30;
+    o->resolve_retry_seconds = RESOLV_RETRY_INFINITE;
+    o->resolve_in_advance = false;
+    o->proto_force = -1;
+#ifdef ENABLE_OCC
+    o->occ = true;
+#endif
+#ifdef ENABLE_MANAGEMENT
+    o->management_log_history_cache = 250;
+    o->management_echo_buffer_size = 100;
+    o->management_state_buffer_size = 100;
+#endif
+#ifdef ENABLE_FEATURE_TUN_PERSIST
+    o->persist_mode = 1;
+#endif
+#ifdef TARGET_LINUX
+    o->tuntap_options.txqueuelen = 100;
+#endif
+#ifdef _WIN32
+#if 0
+    o->tuntap_options.ip_win32_type = IPW32_SET_ADAPTIVE;
+#else
+    o->tuntap_options.ip_win32_type = IPW32_SET_DHCP_MASQ;
+#endif
+    o->tuntap_options.dhcp_lease_time = 31536000; /* one year */
+    o->tuntap_options.dhcp_masq_offset = 0;     /* use network address as internal DHCP server address */
+    o->route_method = ROUTE_METHOD_ADAPTIVE;
+    o->block_outside_dns = false;
+#endif
+#if P2MP_SERVER
+    o->real_hash_size = 256;
+    o->virtual_hash_size = 256;
+    o->n_bcast_buf = 256;
+    o->tcp_queue_limit = 64;
+    o->max_clients = 1024;
+    o->max_routes_per_client = 256;
+    o->stale_routes_check_interval = 0;
+    o->ifconfig_pool_persist_refresh_freq = 600;
+#endif
+#if P2MP
+    o->scheduled_exit_interval = 5;
+#endif
+#ifdef ENABLE_CRYPTO
+    o->ciphername = "BF-CBC";
+#ifdef HAVE_AEAD_CIPHER_MODES /* IV_NCP=2 requires GCM support */
+    o->ncp_enabled = true;
+#else
+    o->ncp_enabled = false;
+#endif
+    o->ncp_ciphers = "AES-256-GCM:AES-128-GCM";
+    o->authname = "SHA1";
+    o->prng_hash = "SHA1";
+    o->prng_nonce_secret_len = 16;
+    o->replay = true;
+    o->replay_window = DEFAULT_SEQ_BACKTRACK;
+    o->replay_time = DEFAULT_TIME_BACKTRACK;
+    o->use_iv = true;
+    o->key_direction = KEY_DIRECTION_BIDIRECTIONAL;
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    o->use_prediction_resistance = false;
+#endif
+    o->key_method = 2;
+    o->tls_timeout = 2;
+    o->renegotiate_bytes = -1;
+    o->renegotiate_seconds = 3600;
+    o->handshake_window = 60;
+    o->transition_window = 3600;
+    o->tls_cert_profile = NULL;
+    o->ecdh_curve = NULL;
+#ifdef ENABLE_X509ALTUSERNAME
+    o->x509_username_field = X509_USERNAME_FIELD_DEFAULT;
+#endif
+#endif /* ENABLE_CRYPTO */
+#ifdef ENABLE_PKCS11
+    o->pkcs11_pin_cache_period = -1;
+#endif                  /* ENABLE_PKCS11 */
+
+/* P2MP server context features */
+#if P2MP_SERVER
+    o->auth_token_generate = false;
+
+    /* Set default --tmp-dir */
+#ifdef _WIN32
+    /* On Windows, find temp dir via enviroment variables */
+    o->tmp_dir = win_get_tempdir();
+#else
+    /* Non-windows platforms use $TMPDIR, and if not set, default to '/tmp' */
+    o->tmp_dir = getenv("TMPDIR");
+    if (!o->tmp_dir)
+    {
+        o->tmp_dir = "/tmp";
+    }
+#endif /* _WIN32 */
+#endif /* P2MP_SERVER */
+    o->allow_recursive_routing = false;
+}
+
+void
+uninit_options(struct options *o)
+{
+    if (o->gc_owned)
+    {
+        gc_free(&o->gc);
+    }
+}
+
+struct pull_filter
+{
+#define PUF_TYPE_UNDEF  0    /** undefined filter type */
+#define PUF_TYPE_ACCEPT 1    /** filter type to accept a matching option */
+#define PUF_TYPE_IGNORE 2    /** filter type to ignore a matching option */
+#define PUF_TYPE_REJECT 3    /** filter type to reject and trigger SIGUSR1 */
+    int type;
+    int size;
+    char *pattern;
+    struct pull_filter *next;
+};
+
+struct pull_filter_list
+{
+    struct pull_filter *head;
+    struct pull_filter *tail;
+};
+
+static const char *
+pull_filter_type_name(int type)
+{
+    if (type == PUF_TYPE_ACCEPT)
+    {
+        return "accept";
+    }
+    if (type == PUF_TYPE_IGNORE)
+    {
+        return "ignore";
+    }
+    if (type == PUF_TYPE_REJECT)
+    {
+        return "reject";
+    }
+    else
+    {
+        return "???";
+    }
+}
+
+#ifndef ENABLE_SMALL
+
+#define SHOW_PARM(name, value, format) msg(D_SHOW_PARMS, "  " #name " = " format, (value))
+#define SHOW_STR(var)       SHOW_PARM(var, (o->var ? o->var : "[UNDEF]"), "'%s'")
+#define SHOW_INT(var)       SHOW_PARM(var, o->var, "%d")
+#define SHOW_UINT(var)      SHOW_PARM(var, o->var, "%u")
+#define SHOW_UNSIGNED(var)  SHOW_PARM(var, o->var, "0x%08x")
+#define SHOW_BOOL(var)      SHOW_PARM(var, (o->var ? "ENABLED" : "DISABLED"), "%s");
+
+#endif
+
+static void
+setenv_connection_entry(struct env_set *es,
+                        const struct connection_entry *e,
+                        const int i)
+{
+    setenv_str_i(es, "proto", proto2ascii(e->proto, e->af, false), i);
+    setenv_str_i(es, "local", e->local, i);
+    setenv_str_i(es, "local_port", e->local_port, i);
+    setenv_str_i(es, "remote", e->remote, i);
+    setenv_str_i(es, "remote_port", e->remote_port, i);
+
+    if (e->http_proxy_options)
+    {
+        setenv_str_i(es, "http_proxy_server", e->http_proxy_options->server, i);
+        setenv_str_i(es, "http_proxy_port", e->http_proxy_options->port, i);
+    }
+    if (e->socks_proxy_server)
+    {
+        setenv_str_i(es, "socks_proxy_server", e->socks_proxy_server, i);
+        setenv_str_i(es, "socks_proxy_port", e->socks_proxy_port, i);
+    }
+}
+
+void
+setenv_settings(struct env_set *es, const struct options *o)
+{
+    setenv_str(es, "config", o->config);
+    setenv_int(es, "verb", o->verbosity);
+    setenv_int(es, "daemon", o->daemon);
+    setenv_int(es, "daemon_log_redirect", o->log);
+    setenv_unsigned(es, "daemon_start_time", time(NULL));
+    setenv_int(es, "daemon_pid", platform_getpid());
+
+    if (o->connection_list)
+    {
+        int i;
+        for (i = 0; i < o->connection_list->len; ++i)
+        {
+            setenv_connection_entry(es, o->connection_list->array[i], i+1);
+        }
+    }
+    else
+    {
+        setenv_connection_entry(es, &o->ce, 1);
+    }
+}
+
+static in_addr_t
+get_ip_addr(const char *ip_string, int msglevel, bool *error)
+{
+    unsigned int flags = GETADDR_HOST_ORDER;
+    bool succeeded = false;
+    in_addr_t ret;
+
+    if (msglevel & M_FATAL)
+    {
+        flags |= GETADDR_FATAL;
+    }
+
+    ret = getaddr(flags, ip_string, 0, &succeeded, NULL);
+    if (!succeeded && error)
+    {
+        *error = true;
+    }
+    return ret;
+}
+
+/**
+ * Returns newly allocated string containing address part without "/nn".
+ *
+ * If gc != NULL, the allocated memory is registered in the supplied gc.
+ */
+static char *
+get_ipv6_addr_no_netbits(const char *addr, struct gc_arena *gc)
+{
+    const char *end = strchr(addr, '/');
+    char *ret = NULL;
+    if (NULL == end)
+    {
+        ret = string_alloc(addr, gc);
+    }
+    else
+    {
+        size_t len = end - addr;
+        ret = gc_malloc(len + 1, true, gc);
+        memcpy(ret, addr, len);
+    }
+    return ret;
+}
+
+static bool
+ipv6_addr_safe_hexplusbits( const char *ipv6_prefix_spec )
+{
+    struct in6_addr t_addr;
+    unsigned int t_bits;
+
+    return get_ipv6_addr( ipv6_prefix_spec, &t_addr, &t_bits, M_WARN );
+}
+
+static char *
+string_substitute(const char *src, int from, int to, struct gc_arena *gc)
+{
+    char *ret = (char *) gc_malloc(strlen(src) + 1, true, gc);
+    char *dest = ret;
+    char c;
+
+    do
+    {
+        c = *src++;
+        if (c == from)
+        {
+            c = to;
+        }
+        *dest++ = c;
+    }
+    while (c);
+    return ret;
+}
+
+#ifdef ENABLE_CRYPTO
+static uint8_t *
+parse_hash_fingerprint(const char *str, int nbytes, int msglevel, struct gc_arena *gc)
+{
+    int i;
+    const char *cp = str;
+    uint8_t *ret = (uint8_t *) gc_malloc(nbytes, true, gc);
+    char term = 1;
+    int byte;
+    char bs[3];
+
+    for (i = 0; i < nbytes; ++i)
+    {
+        if (strlen(cp) < 2)
+        {
+            msg(msglevel, "format error in hash fingerprint: %s", str);
+        }
+        bs[0] = *cp++;
+        bs[1] = *cp++;
+        bs[2] = 0;
+        byte = 0;
+        if (sscanf(bs, "%x", &byte) != 1)
+        {
+            msg(msglevel, "format error in hash fingerprint hex byte: %s", str);
+        }
+        ret[i] = (uint8_t)byte;
+        term = *cp++;
+        if (term != ':' && term != 0)
+        {
+            msg(msglevel, "format error in hash fingerprint delimiter: %s", str);
+        }
+        if (term == 0)
+        {
+            break;
+        }
+    }
+    if (term != 0 || i != nbytes-1)
+    {
+        msg(msglevel, "hash fingerprint is different length than expected (%d bytes): %s", nbytes, str);
+    }
+    return ret;
+}
+#endif /* ifdef ENABLE_CRYPTO */
+
+#ifdef _WIN32
+
+#ifndef ENABLE_SMALL
+
+static void
+show_dhcp_option_addrs(const char *name, const in_addr_t *array, int len)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    for (i = 0; i < len; ++i)
+    {
+        msg(D_SHOW_PARMS, "  %s[%d] = %s",
+            name,
+            i,
+            print_in_addr_t(array[i], 0, &gc));
+    }
+    gc_free(&gc);
+}
+
+static void
+show_tuntap_options(const struct tuntap_options *o)
+{
+    SHOW_BOOL(ip_win32_defined);
+    SHOW_INT(ip_win32_type);
+    SHOW_INT(dhcp_masq_offset);
+    SHOW_INT(dhcp_lease_time);
+    SHOW_INT(tap_sleep);
+    SHOW_BOOL(dhcp_options);
+    SHOW_BOOL(dhcp_renew);
+    SHOW_BOOL(dhcp_pre_release);
+    SHOW_STR(domain);
+    SHOW_STR(netbios_scope);
+    SHOW_INT(netbios_node_type);
+    SHOW_BOOL(disable_nbt);
+
+    show_dhcp_option_addrs("DNS", o->dns, o->dns_len);
+    show_dhcp_option_addrs("WINS", o->wins, o->wins_len);
+    show_dhcp_option_addrs("NTP", o->ntp, o->ntp_len);
+    show_dhcp_option_addrs("NBDD", o->nbdd, o->nbdd_len);
+}
+
+#endif /* ifndef ENABLE_SMALL */
+#endif /* ifdef _WIN32 */
+
+#if defined(_WIN32) || defined(TARGET_ANDROID)
+static void
+dhcp_option_dns6_parse(const char *parm, struct in6_addr *dns6_list, int *len, int msglevel)
+{
+    struct in6_addr addr;
+    if (*len >= N_DHCP_ADDR)
+    {
+        msg(msglevel, "--dhcp-option DNS: maximum of %d IPv6 dns servers can be specified",
+            N_DHCP_ADDR);
+    }
+    else if (get_ipv6_addr(parm, &addr, NULL, msglevel))
+    {
+        dns6_list[(*len)++] = addr;
+    }
+}
+static void
+dhcp_option_address_parse(const char *name, const char *parm, in_addr_t *array, int *len, int msglevel)
+{
+    if (*len >= N_DHCP_ADDR)
+    {
+        msg(msglevel, "--dhcp-option %s: maximum of %d %s servers can be specified",
+            name,
+            N_DHCP_ADDR,
+            name);
+    }
+    else
+    {
+        if (ip_addr_dotted_quad_safe(parm)) /* FQDN -- IP address only */
+        {
+            bool error = false;
+            const in_addr_t addr = get_ip_addr(parm, msglevel, &error);
+            if (!error)
+            {
+                array[(*len)++] = addr;
+            }
+        }
+        else
+        {
+            msg(msglevel, "dhcp-option parameter %s '%s' must be an IP address", name, parm);
+        }
+    }
+}
+
+#endif /* if defined(_WIN32) || defined(TARGET_ANDROID) */
+
+#if P2MP
+
+#ifndef ENABLE_SMALL
+
+static void
+show_p2mp_parms(const struct options *o)
+{
+    struct gc_arena gc = gc_new();
+
+#if P2MP_SERVER
+    msg(D_SHOW_PARMS, "  server_network = %s", print_in_addr_t(o->server_network, 0, &gc));
+    msg(D_SHOW_PARMS, "  server_netmask = %s", print_in_addr_t(o->server_netmask, 0, &gc));
+    msg(D_SHOW_PARMS, "  server_network_ipv6 = %s", print_in6_addr(o->server_network_ipv6, 0, &gc) );
+    SHOW_INT(server_netbits_ipv6);
+    msg(D_SHOW_PARMS, "  server_bridge_ip = %s", print_in_addr_t(o->server_bridge_ip, 0, &gc));
+    msg(D_SHOW_PARMS, "  server_bridge_netmask = %s", print_in_addr_t(o->server_bridge_netmask, 0, &gc));
+    msg(D_SHOW_PARMS, "  server_bridge_pool_start = %s", print_in_addr_t(o->server_bridge_pool_start, 0, &gc));
+    msg(D_SHOW_PARMS, "  server_bridge_pool_end = %s", print_in_addr_t(o->server_bridge_pool_end, 0, &gc));
+    if (o->push_list.head)
+    {
+        const struct push_entry *e = o->push_list.head;
+        while (e)
+        {
+            if (e->enable)
+            {
+                msg(D_SHOW_PARMS, "  push_entry = '%s'", e->option);
+            }
+            e = e->next;
+        }
+    }
+    SHOW_BOOL(ifconfig_pool_defined);
+    msg(D_SHOW_PARMS, "  ifconfig_pool_start = %s", print_in_addr_t(o->ifconfig_pool_start, 0, &gc));
+    msg(D_SHOW_PARMS, "  ifconfig_pool_end = %s", print_in_addr_t(o->ifconfig_pool_end, 0, &gc));
+    msg(D_SHOW_PARMS, "  ifconfig_pool_netmask = %s", print_in_addr_t(o->ifconfig_pool_netmask, 0, &gc));
+    SHOW_STR(ifconfig_pool_persist_filename);
+    SHOW_INT(ifconfig_pool_persist_refresh_freq);
+    SHOW_BOOL(ifconfig_ipv6_pool_defined);
+    msg(D_SHOW_PARMS, "  ifconfig_ipv6_pool_base = %s", print_in6_addr(o->ifconfig_ipv6_pool_base, 0, &gc));
+    SHOW_INT(ifconfig_ipv6_pool_netbits);
+    SHOW_INT(n_bcast_buf);
+    SHOW_INT(tcp_queue_limit);
+    SHOW_INT(real_hash_size);
+    SHOW_INT(virtual_hash_size);
+    SHOW_STR(client_connect_script);
+    SHOW_STR(learn_address_script);
+    SHOW_STR(client_disconnect_script);
+    SHOW_STR(client_config_dir);
+    SHOW_BOOL(ccd_exclusive);
+    SHOW_STR(tmp_dir);
+    SHOW_BOOL(push_ifconfig_defined);
+    msg(D_SHOW_PARMS, "  push_ifconfig_local = %s", print_in_addr_t(o->push_ifconfig_local, 0, &gc));
+    msg(D_SHOW_PARMS, "  push_ifconfig_remote_netmask = %s", print_in_addr_t(o->push_ifconfig_remote_netmask, 0, &gc));
+    SHOW_BOOL(push_ifconfig_ipv6_defined);
+    msg(D_SHOW_PARMS, "  push_ifconfig_ipv6_local = %s/%d", print_in6_addr(o->push_ifconfig_ipv6_local, 0, &gc), o->push_ifconfig_ipv6_netbits );
+    msg(D_SHOW_PARMS, "  push_ifconfig_ipv6_remote = %s", print_in6_addr(o->push_ifconfig_ipv6_remote, 0, &gc));
+    SHOW_BOOL(enable_c2c);
+    SHOW_BOOL(duplicate_cn);
+    SHOW_INT(cf_max);
+    SHOW_INT(cf_per);
+    SHOW_INT(max_clients);
+    SHOW_INT(max_routes_per_client);
+    SHOW_STR(auth_user_pass_verify_script);
+    SHOW_BOOL(auth_user_pass_verify_script_via_file);
+    SHOW_BOOL(auth_token_generate);
+    SHOW_INT(auth_token_lifetime);
+#if PORT_SHARE
+    SHOW_STR(port_share_host);
+    SHOW_STR(port_share_port);
+#endif
+#endif /* P2MP_SERVER */
+
+    SHOW_BOOL(client);
+    SHOW_BOOL(pull);
+    SHOW_STR(auth_user_pass_file);
+
+    gc_free(&gc);
+}
+
+#endif /* ! ENABLE_SMALL */
+
+#if P2MP_SERVER
+
+static void
+option_iroute(struct options *o,
+              const char *network_str,
+              const char *netmask_str,
+              int msglevel)
+{
+    struct iroute *ir;
+
+    ALLOC_OBJ_GC(ir, struct iroute, &o->gc);
+    ir->network = getaddr(GETADDR_HOST_ORDER, network_str, 0, NULL, NULL);
+    ir->netbits = -1;
+
+    if (netmask_str)
+    {
+        const in_addr_t netmask = getaddr(GETADDR_HOST_ORDER, netmask_str, 0, NULL, NULL);
+        if (!netmask_to_netbits(ir->network, netmask, &ir->netbits))
+        {
+            msg(msglevel, "in --iroute %s %s : Bad network/subnet specification",
+                network_str,
+                netmask_str);
+            return;
+        }
+    }
+
+    ir->next = o->iroutes;
+    o->iroutes = ir;
+}
+
+static void
+option_iroute_ipv6(struct options *o,
+                   const char *prefix_str,
+                   int msglevel)
+{
+    struct iroute_ipv6 *ir;
+
+    ALLOC_OBJ_GC(ir, struct iroute_ipv6, &o->gc);
+
+    if (!get_ipv6_addr(prefix_str, &ir->network, &ir->netbits, msglevel ))
+    {
+        msg(msglevel, "in --iroute-ipv6 %s: Bad IPv6 prefix specification",
+            prefix_str);
+        return;
+    }
+
+    ir->next = o->iroutes_ipv6;
+    o->iroutes_ipv6 = ir;
+}
+#endif /* P2MP_SERVER */
+#endif /* P2MP */
+
+#ifndef ENABLE_SMALL
+static void
+show_http_proxy_options(const struct http_proxy_options *o)
+{
+    int i;
+    msg(D_SHOW_PARMS, "BEGIN http_proxy");
+    SHOW_STR(server);
+    SHOW_STR(port);
+    SHOW_STR(auth_method_string);
+    SHOW_STR(auth_file);
+    SHOW_STR(http_version);
+    SHOW_STR(user_agent);
+    for  (i = 0; i < MAX_CUSTOM_HTTP_HEADER && o->custom_headers[i].name; i++)
+    {
+        if (o->custom_headers[i].content)
+        {
+            msg(D_SHOW_PARMS, "  custom_header[%d] = %s: %s", i,
+                o->custom_headers[i].name, o->custom_headers[i].content);
+        }
+        else
+        {
+            msg(D_SHOW_PARMS, "  custom_header[%d] = %s", i,
+                o->custom_headers[i].name);
+        }
+    }
+    msg(D_SHOW_PARMS, "END http_proxy");
+}
+#endif /* ifndef ENABLE_SMALL */
+
+void
+options_detach(struct options *o)
+{
+    gc_detach(&o->gc);
+    o->routes = NULL;
+    o->client_nat = NULL;
+#if P2MP_SERVER
+    clone_push_list(o);
+#endif
+}
+
+void
+rol_check_alloc(struct options *options)
+{
+    if (!options->routes)
+    {
+        options->routes = new_route_option_list(&options->gc);
+    }
+}
+
+static void
+rol6_check_alloc(struct options *options)
+{
+    if (!options->routes_ipv6)
+    {
+        options->routes_ipv6 = new_route_ipv6_option_list(&options->gc);
+    }
+}
+
+static void
+cnol_check_alloc(struct options *options)
+{
+    if (!options->client_nat)
+    {
+        options->client_nat = new_client_nat_list(&options->gc);
+    }
+}
+
+#ifndef ENABLE_SMALL
+static void
+show_connection_entry(const struct connection_entry *o)
+{
+    msg(D_SHOW_PARMS, "  proto = %s", proto2ascii(o->proto, o->af, false));
+    SHOW_STR(local);
+    SHOW_STR(local_port);
+    SHOW_STR(remote);
+    SHOW_STR(remote_port);
+    SHOW_BOOL(remote_float);
+    SHOW_BOOL(bind_defined);
+    SHOW_BOOL(bind_local);
+    SHOW_BOOL(bind_ipv6_only);
+    SHOW_INT(connect_retry_seconds);
+    SHOW_INT(connect_timeout);
+
+    if (o->http_proxy_options)
+    {
+        show_http_proxy_options(o->http_proxy_options);
+    }
+    SHOW_STR(socks_proxy_server);
+    SHOW_STR(socks_proxy_port);
+    SHOW_INT(tun_mtu);
+    SHOW_BOOL(tun_mtu_defined);
+    SHOW_INT(link_mtu);
+    SHOW_BOOL(link_mtu_defined);
+    SHOW_INT(tun_mtu_extra);
+    SHOW_BOOL(tun_mtu_extra_defined);
+
+    SHOW_INT(mtu_discover_type);
+
+#ifdef ENABLE_FRAGMENT
+    SHOW_INT(fragment);
+#endif
+    SHOW_INT(mssfix);
+
+#ifdef ENABLE_OCC
+    SHOW_INT(explicit_exit_notification);
+#endif
+}
+
+
+static void
+show_connection_entries(const struct options *o)
+{
+    if (o->connection_list)
+    {
+        const struct connection_list *l = o->connection_list;
+        int i;
+        for (i = 0; i < l->len; ++i)
+        {
+            msg(D_SHOW_PARMS, "Connection profiles [%d]:", i);
+            show_connection_entry(l->array[i]);
+        }
+    }
+    else
+    {
+        msg(D_SHOW_PARMS, "Connection profiles [default]:");
+        show_connection_entry(&o->ce);
+    }
+    msg(D_SHOW_PARMS, "Connection profiles END");
+}
+
+static void
+show_pull_filter_list(const struct pull_filter_list *l)
+{
+    struct pull_filter *f;
+    if (!l)
+    {
+        return;
+    }
+
+    msg(D_SHOW_PARMS, "  Pull filters:");
+    for (f = l->head; f; f = f->next)
+    {
+        msg(D_SHOW_PARMS, "    %s \"%s\"", pull_filter_type_name(f->type), f->pattern);
+    }
+}
+
+#endif /* ifndef ENABLE_SMALL */
+
+void
+show_settings(const struct options *o)
+{
+#ifndef ENABLE_SMALL
+    msg(D_SHOW_PARMS, "Current Parameter Settings:");
+
+    SHOW_STR(config);
+
+    SHOW_INT(mode);
+
+#ifdef ENABLE_FEATURE_TUN_PERSIST
+    SHOW_BOOL(persist_config);
+    SHOW_INT(persist_mode);
+#endif
+
+#ifdef ENABLE_CRYPTO
+    SHOW_BOOL(show_ciphers);
+    SHOW_BOOL(show_digests);
+    SHOW_BOOL(show_engines);
+    SHOW_BOOL(genkey);
+    SHOW_STR(key_pass_file);
+    SHOW_BOOL(show_tls_ciphers);
+#endif
+
+    SHOW_INT(connect_retry_max);
+    show_connection_entries(o);
+
+    SHOW_BOOL(remote_random);
+
+    SHOW_STR(ipchange);
+    SHOW_STR(dev);
+    SHOW_STR(dev_type);
+    SHOW_STR(dev_node);
+    SHOW_STR(lladdr);
+    SHOW_INT(topology);
+    SHOW_STR(ifconfig_local);
+    SHOW_STR(ifconfig_remote_netmask);
+    SHOW_BOOL(ifconfig_noexec);
+    SHOW_BOOL(ifconfig_nowarn);
+    SHOW_STR(ifconfig_ipv6_local);
+    SHOW_INT(ifconfig_ipv6_netbits);
+    SHOW_STR(ifconfig_ipv6_remote);
+
+#ifdef ENABLE_FEATURE_SHAPER
+    SHOW_INT(shaper);
+#endif
+#ifdef ENABLE_OCC
+    SHOW_INT(mtu_test);
+#endif
+
+    SHOW_BOOL(mlock);
+
+    SHOW_INT(keepalive_ping);
+    SHOW_INT(keepalive_timeout);
+    SHOW_INT(inactivity_timeout);
+    SHOW_INT(ping_send_timeout);
+    SHOW_INT(ping_rec_timeout);
+    SHOW_INT(ping_rec_timeout_action);
+    SHOW_BOOL(ping_timer_remote);
+    SHOW_INT(remap_sigusr1);
+    SHOW_BOOL(persist_tun);
+    SHOW_BOOL(persist_local_ip);
+    SHOW_BOOL(persist_remote_ip);
+    SHOW_BOOL(persist_key);
+
+#if PASSTOS_CAPABILITY
+    SHOW_BOOL(passtos);
+#endif
+
+    SHOW_INT(resolve_retry_seconds);
+    SHOW_BOOL(resolve_in_advance);
+
+    SHOW_STR(username);
+    SHOW_STR(groupname);
+    SHOW_STR(chroot_dir);
+    SHOW_STR(cd_dir);
+#ifdef ENABLE_SELINUX
+    SHOW_STR(selinux_context);
+#endif
+    SHOW_STR(writepid);
+    SHOW_STR(up_script);
+    SHOW_STR(down_script);
+    SHOW_BOOL(down_pre);
+    SHOW_BOOL(up_restart);
+    SHOW_BOOL(up_delay);
+    SHOW_BOOL(daemon);
+    SHOW_INT(inetd);
+    SHOW_BOOL(log);
+    SHOW_BOOL(suppress_timestamps);
+    SHOW_BOOL(machine_readable_output);
+    SHOW_INT(nice);
+    SHOW_INT(verbosity);
+    SHOW_INT(mute);
+#ifdef ENABLE_DEBUG
+    SHOW_INT(gremlin);
+#endif
+    SHOW_STR(status_file);
+    SHOW_INT(status_file_version);
+    SHOW_INT(status_file_update_freq);
+
+#ifdef ENABLE_OCC
+    SHOW_BOOL(occ);
+#endif
+    SHOW_INT(rcvbuf);
+    SHOW_INT(sndbuf);
+#if defined(TARGET_LINUX) && HAVE_DECL_SO_MARK
+    SHOW_INT(mark);
+#endif
+    SHOW_INT(sockflags);
+
+    SHOW_BOOL(fast_io);
+
+#ifdef USE_COMP
+    SHOW_INT(comp.alg);
+    SHOW_INT(comp.flags);
+#endif
+
+    SHOW_STR(route_script);
+    SHOW_STR(route_default_gateway);
+    SHOW_INT(route_default_metric);
+    SHOW_BOOL(route_noexec);
+    SHOW_INT(route_delay);
+    SHOW_INT(route_delay_window);
+    SHOW_BOOL(route_delay_defined);
+    SHOW_BOOL(route_nopull);
+    SHOW_BOOL(route_gateway_via_dhcp);
+    SHOW_BOOL(allow_pull_fqdn);
+    show_pull_filter_list(o->pull_filter_list);
+
+    if (o->routes)
+    {
+        print_route_options(o->routes, D_SHOW_PARMS);
+    }
+
+    if (o->client_nat)
+    {
+        print_client_nat_list(o->client_nat, D_SHOW_PARMS);
+    }
+
+#ifdef ENABLE_MANAGEMENT
+    SHOW_STR(management_addr);
+    SHOW_STR(management_port);
+    SHOW_STR(management_user_pass);
+    SHOW_INT(management_log_history_cache);
+    SHOW_INT(management_echo_buffer_size);
+    SHOW_STR(management_write_peer_info_file);
+    SHOW_STR(management_client_user);
+    SHOW_STR(management_client_group);
+    SHOW_INT(management_flags);
+#endif
+#ifdef ENABLE_PLUGIN
+    if (o->plugin_list)
+    {
+        plugin_option_list_print(o->plugin_list, D_SHOW_PARMS);
+    }
+#endif
+
+#ifdef ENABLE_CRYPTO
+    SHOW_STR(shared_secret_file);
+    SHOW_PARM(key_direction, keydirection2ascii(o->key_direction, false, true), "%s");
+    SHOW_STR(ciphername);
+    SHOW_BOOL(ncp_enabled);
+    SHOW_STR(ncp_ciphers);
+    SHOW_STR(authname);
+    SHOW_STR(prng_hash);
+    SHOW_INT(prng_nonce_secret_len);
+    SHOW_INT(keysize);
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    SHOW_BOOL(engine);
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+    SHOW_BOOL(replay);
+    SHOW_BOOL(mute_replay_warnings);
+    SHOW_INT(replay_window);
+    SHOW_INT(replay_time);
+    SHOW_STR(packet_id_file);
+    SHOW_BOOL(use_iv);
+    SHOW_BOOL(test_crypto);
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    SHOW_BOOL(use_prediction_resistance);
+#endif
+
+    SHOW_BOOL(tls_server);
+    SHOW_BOOL(tls_client);
+    SHOW_INT(key_method);
+    SHOW_STR(ca_file);
+    SHOW_STR(ca_path);
+    SHOW_STR(dh_file);
+#ifdef MANAGMENT_EXTERNAL_KEY
+    if ((o->management_flags & MF_EXTERNAL_CERT))
+    {
+        SHOW_PARM("cert_file","EXTERNAL_CERT","%s");
+    }
+    else
+#endif
+    SHOW_STR(cert_file);
+    SHOW_STR(extra_certs_file);
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+    if ((o->management_flags & MF_EXTERNAL_KEY))
+    {
+        SHOW_PARM("priv_key_file","EXTERNAL_PRIVATE_KEY","%s");
+    }
+    else
+#endif
+    SHOW_STR(priv_key_file);
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    SHOW_STR(pkcs12_file);
+#endif
+#ifdef ENABLE_CRYPTOAPI
+    SHOW_STR(cryptoapi_cert);
+#endif
+    SHOW_STR(cipher_list);
+    SHOW_STR(cipher_list_tls13);
+    SHOW_STR(tls_cert_profile);
+    SHOW_STR(tls_verify);
+    SHOW_STR(tls_export_cert);
+    SHOW_INT(verify_x509_type);
+    SHOW_STR(verify_x509_name);
+    SHOW_STR(crl_file);
+    SHOW_INT(ns_cert_type);
+    {
+        int i;
+        for (i = 0; i<MAX_PARMS; i++)
+        {
+            SHOW_INT(remote_cert_ku[i]);
+        }
+    }
+    SHOW_STR(remote_cert_eku);
+    SHOW_INT(ssl_flags);
+
+    SHOW_INT(tls_timeout);
+
+    SHOW_INT(renegotiate_bytes);
+    SHOW_INT(renegotiate_packets);
+    SHOW_INT(renegotiate_seconds);
+
+    SHOW_INT(handshake_window);
+    SHOW_INT(transition_window);
+
+    SHOW_BOOL(single_session);
+#ifdef ENABLE_PUSH_PEER_INFO
+    SHOW_BOOL(push_peer_info);
+#endif
+    SHOW_BOOL(tls_exit);
+
+    SHOW_STR(tls_auth_file);
+    SHOW_STR(tls_crypt_file);
+#endif /* ENABLE_CRYPTO */
+
+#ifdef ENABLE_PKCS11
+    {
+        int i;
+        for (i = 0; i<MAX_PARMS && o->pkcs11_providers[i] != NULL; i++)
+        {
+            SHOW_PARM(pkcs11_providers, o->pkcs11_providers[i], "%s");
+        }
+    }
+    {
+        int i;
+        for (i = 0; i<MAX_PARMS; i++)
+        {
+            SHOW_PARM(pkcs11_protected_authentication, o->pkcs11_protected_authentication[i] ? "ENABLED" : "DISABLED", "%s");
+        }
+    }
+    {
+        int i;
+        for (i = 0; i<MAX_PARMS; i++)
+        {
+            SHOW_PARM(pkcs11_private_mode, o->pkcs11_private_mode[i], "%08x");
+        }
+    }
+    {
+        int i;
+        for (i = 0; i<MAX_PARMS; i++)
+        {
+            SHOW_PARM(pkcs11_cert_private, o->pkcs11_cert_private[i] ? "ENABLED" : "DISABLED", "%s");
+        }
+    }
+    SHOW_INT(pkcs11_pin_cache_period);
+    SHOW_STR(pkcs11_id);
+    SHOW_BOOL(pkcs11_id_management);
+#endif                  /* ENABLE_PKCS11 */
+
+#if P2MP
+    show_p2mp_parms(o);
+#endif
+
+#ifdef _WIN32
+    SHOW_BOOL(show_net_up);
+    SHOW_INT(route_method);
+    SHOW_BOOL(block_outside_dns);
+    show_tuntap_options(&o->tuntap_options);
+#endif
+#endif /* ifndef ENABLE_SMALL */
+}
+
+#undef SHOW_PARM
+#undef SHOW_STR
+#undef SHOW_INT
+#undef SHOW_BOOL
+
+#ifdef ENABLE_MANAGEMENT
+
+static struct http_proxy_options *
+parse_http_proxy_override(const char *server,
+                          const char *port,
+                          const char *flags,
+                          const int msglevel,
+                          struct gc_arena *gc)
+{
+    if (server && port)
+    {
+        struct http_proxy_options *ho;
+        ALLOC_OBJ_CLEAR_GC(ho, struct http_proxy_options, gc);
+        ho->server = string_alloc(server, gc);
+        ho->port = port;
+        if (flags && !strcmp(flags, "nct"))
+        {
+            ho->auth_retry = PAR_NCT;
+        }
+        else
+        {
+            ho->auth_retry = PAR_ALL;
+        }
+        ho->http_version = "1.0";
+        ho->user_agent = "OpenVPN-Autoproxy/1.0";
+        return ho;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+static void
+options_postprocess_http_proxy_override(struct options *o)
+{
+    const struct connection_list *l = o->connection_list;
+    int i;
+    bool succeed = false;
+    for (i = 0; i < l->len; ++i)
+    {
+        struct connection_entry *ce = l->array[i];
+        if (ce->proto == PROTO_TCP_CLIENT || ce->proto == PROTO_TCP)
+        {
+            ce->http_proxy_options = o->http_proxy_override;
+            succeed = true;
+        }
+    }
+    if (succeed)
+    {
+        for (i = 0; i < l->len; ++i)
+        {
+            struct connection_entry *ce = l->array[i];
+            if (ce->proto == PROTO_UDP)
+            {
+                ce->flags |= CE_DISABLED;
+            }
+        }
+    }
+    else
+    {
+        msg(M_WARN, "Note: option http-proxy-override ignored because no TCP-based connection profiles are defined");
+    }
+}
+
+#endif /* ifdef ENABLE_MANAGEMENT */
+
+static struct connection_list *
+alloc_connection_list_if_undef(struct options *options)
+{
+    if (!options->connection_list)
+    {
+        ALLOC_OBJ_CLEAR_GC(options->connection_list, struct connection_list, &options->gc);
+    }
+    return options->connection_list;
+}
+
+static struct connection_entry *
+alloc_connection_entry(struct options *options, const int msglevel)
+{
+    struct connection_list *l = alloc_connection_list_if_undef(options);
+    struct connection_entry *e;
+
+    if (l->len >= CONNECTION_LIST_SIZE)
+    {
+        msg(msglevel, "Maximum number of 'connection' options (%d) exceeded", CONNECTION_LIST_SIZE);
+        return NULL;
+    }
+    ALLOC_OBJ_GC(e, struct connection_entry, &options->gc);
+    l->array[l->len++] = e;
+    return e;
+}
+
+static struct remote_list *
+alloc_remote_list_if_undef(struct options *options)
+{
+    if (!options->remote_list)
+    {
+        ALLOC_OBJ_CLEAR_GC(options->remote_list, struct remote_list, &options->gc);
+    }
+    return options->remote_list;
+}
+
+static struct remote_entry *
+alloc_remote_entry(struct options *options, const int msglevel)
+{
+    struct remote_list *l = alloc_remote_list_if_undef(options);
+    struct remote_entry *e;
+
+    if (l->len >= CONNECTION_LIST_SIZE)
+    {
+        msg(msglevel, "Maximum number of 'remote' options (%d) exceeded", CONNECTION_LIST_SIZE);
+        return NULL;
+    }
+    ALLOC_OBJ_GC(e, struct remote_entry, &options->gc);
+    l->array[l->len++] = e;
+    return e;
+}
+
+static struct pull_filter_list *
+alloc_pull_filter_list(struct options *o)
+{
+    if (!o->pull_filter_list)
+    {
+        ALLOC_OBJ_CLEAR_GC(o->pull_filter_list, struct pull_filter_list, &o->gc);
+    }
+    return o->pull_filter_list;
+}
+
+static struct pull_filter *
+alloc_pull_filter(struct options *o, const int msglevel)
+{
+    struct pull_filter_list *l = alloc_pull_filter_list(o);
+    struct pull_filter *f;
+
+    ALLOC_OBJ_CLEAR_GC(f, struct pull_filter, &o->gc);
+    if (l->head)
+    {
+        ASSERT(l->tail);
+        l->tail->next = f;
+    }
+    else
+    {
+        ASSERT(!l->tail);
+        l->head = f;
+    }
+    l->tail = f;
+    return f;
+}
+
+static void
+connection_entry_load_re(struct connection_entry *ce, const struct remote_entry *re)
+{
+    if (re->remote)
+    {
+        ce->remote = re->remote;
+    }
+    if (re->remote_port)
+    {
+        ce->remote_port = re->remote_port;
+    }
+    if (re->proto >= 0)
+    {
+        ce->proto = re->proto;
+    }
+    if (re->af > 0)
+    {
+        ce->af = re->af;
+    }
+}
+
+static void
+options_postprocess_verify_ce(const struct options *options, const struct connection_entry *ce)
+{
+    struct options defaults;
+    int dev = DEV_TYPE_UNDEF;
+    bool pull = false;
+
+    init_options(&defaults, true);
+
+#ifdef ENABLE_CRYPTO
+    if (options->test_crypto)
+    {
+        notnull(options->shared_secret_file, "key file (--secret)");
+    }
+    else
+#endif
+    notnull(options->dev, "TUN/TAP device (--dev)");
+
+    /*
+     * Get tun/tap/null device type
+     */
+    dev = dev_type_enum(options->dev, options->dev_type);
+
+    /*
+     * If "proto tcp" is specified, make sure we know whether it is
+     * tcp-client or tcp-server.
+     */
+    if (ce->proto == PROTO_TCP)
+    {
+        msg(M_USAGE, "--proto tcp is ambiguous in this context.  Please specify --proto tcp-server or --proto tcp-client");
+    }
+
+    /*
+     * Sanity check on daemon/inetd modes
+     */
+
+    if (options->daemon && options->inetd)
+    {
+        msg(M_USAGE, "only one of --daemon or --inetd may be specified");
+    }
+
+    if (options->inetd && (ce->local || ce->remote))
+    {
+        msg(M_USAGE, "--local or --remote cannot be used with --inetd");
+    }
+
+    if (options->inetd && ce->proto == PROTO_TCP_CLIENT)
+    {
+        msg(M_USAGE, "--proto tcp-client cannot be used with --inetd");
+    }
+
+    if (options->inetd == INETD_NOWAIT && ce->proto != PROTO_TCP_SERVER)
+    {
+        msg(M_USAGE, "--inetd nowait can only be used with --proto tcp-server");
+    }
+
+    if (options->inetd == INETD_NOWAIT
+#ifdef ENABLE_CRYPTO
+        && !(options->tls_server || options->tls_client)
+#endif
+        )
+    {
+        msg(M_USAGE, "--inetd nowait can only be used in TLS mode");
+    }
+
+    if (options->inetd == INETD_NOWAIT && dev != DEV_TYPE_TAP)
+    {
+        msg(M_USAGE, "--inetd nowait only makes sense in --dev tap mode");
+    }
+
+
+    if (options->lladdr && dev != DEV_TYPE_TAP)
+    {
+        msg(M_USAGE, "--lladdr can only be used in --dev tap mode");
+    }
+
+    /*
+     * Sanity check on MTU parameters
+     */
+    if (options->ce.tun_mtu_defined && options->ce.link_mtu_defined)
+    {
+        msg(M_USAGE, "only one of --tun-mtu or --link-mtu may be defined (note that --ifconfig implies --link-mtu %d)", LINK_MTU_DEFAULT);
+    }
+
+#ifdef ENABLE_OCC
+    if (!proto_is_udp(ce->proto) && options->mtu_test)
+    {
+        msg(M_USAGE, "--mtu-test only makes sense with --proto udp");
+    }
+#endif
+
+    /* will we be pulling options from server? */
+#if P2MP
+    pull = options->pull;
+#endif
+
+    /*
+     * Sanity check on --local, --remote, and --ifconfig
+     */
+
+    if (proto_is_net(ce->proto)
+        && string_defined_equal(ce->local, ce->remote)
+        && string_defined_equal(ce->local_port, ce->remote_port))
+    {
+        msg(M_USAGE, "--remote and --local addresses are the same");
+    }
+
+    if (string_defined_equal(ce->remote, options->ifconfig_local)
+        || string_defined_equal(ce->remote, options->ifconfig_remote_netmask))
+    {
+        msg(M_USAGE, "--local and --remote addresses must be distinct from --ifconfig addresses");
+    }
+
+    if (string_defined_equal(ce->local, options->ifconfig_local)
+        || string_defined_equal(ce->local, options->ifconfig_remote_netmask))
+    {
+        msg(M_USAGE, "--local addresses must be distinct from --ifconfig addresses");
+    }
+
+    if (string_defined_equal(options->ifconfig_local, options->ifconfig_remote_netmask))
+    {
+        msg(M_USAGE, "local and remote/netmask --ifconfig addresses must be different");
+    }
+
+    if (ce->bind_defined && !ce->bind_local)
+    {
+        msg(M_USAGE, "--bind and --nobind can't be used together");
+    }
+
+    if (ce->local && !ce->bind_local)
+    {
+        msg(M_USAGE, "--local and --nobind don't make sense when used together");
+    }
+
+    if (ce->local_port_defined && !ce->bind_local)
+    {
+        msg(M_USAGE, "--lport and --nobind don't make sense when used together");
+    }
+
+    if (!ce->remote && !ce->bind_local)
+    {
+        msg(M_USAGE, "--nobind doesn't make sense unless used with --remote");
+    }
+
+    /*
+     * Check for consistency of management options
+     */
+#ifdef ENABLE_MANAGEMENT
+    if (!options->management_addr
+        && (options->management_flags
+            || options->management_write_peer_info_file
+            || options->management_log_history_cache != defaults.management_log_history_cache))
+    {
+        msg(M_USAGE, "--management is not specified, however one or more options which modify the behavior of --management were specified");
+    }
+
+    if ((options->management_client_user || options->management_client_group)
+        && !(options->management_flags & MF_UNIX_SOCK))
+    {
+        msg(M_USAGE, "--management-client-(user|group) can only be used on unix domain sockets");
+    }
+
+    if (options->management_addr
+        && !(options->management_flags & MF_UNIX_SOCK)
+        && (!options->management_user_pass))
+    {
+        msg(M_WARN, "WARNING: Using --management on a TCP port WITHOUT "
+            "passwords is STRONGLY discouraged and considered insecure");
+    }
+
+#endif
+
+    /*
+     * Windows-specific options.
+     */
+
+#ifdef _WIN32
+    if (dev == DEV_TYPE_TUN && !(pull || (options->ifconfig_local && options->ifconfig_remote_netmask)))
+    {
+        msg(M_USAGE, "On Windows, --ifconfig is required when --dev tun is used");
+    }
+
+    if ((options->tuntap_options.ip_win32_defined)
+        && !(pull || (options->ifconfig_local && options->ifconfig_remote_netmask)))
+    {
+        msg(M_USAGE, "On Windows, --ip-win32 doesn't make sense unless --ifconfig is also used");
+    }
+
+    if (options->tuntap_options.dhcp_options
+        && options->tuntap_options.ip_win32_type != IPW32_SET_DHCP_MASQ
+        && options->tuntap_options.ip_win32_type != IPW32_SET_ADAPTIVE)
+    {
+        msg(M_USAGE, "--dhcp-options requires --ip-win32 dynamic or adaptive");
+    }
+#endif
+
+    /*
+     * Check that protocol options make sense.
+     */
+
+#ifdef ENABLE_FRAGMENT
+    if (!proto_is_udp(ce->proto) && ce->fragment)
+    {
+        msg(M_USAGE, "--fragment can only be used with --proto udp");
+    }
+#endif
+
+#ifdef ENABLE_OCC
+    if (!proto_is_udp(ce->proto) && ce->explicit_exit_notification)
+    {
+        msg(M_USAGE, "--explicit-exit-notify can only be used with --proto udp");
+    }
+#endif
+
+    if (!ce->remote && ce->proto == PROTO_TCP_CLIENT)
+    {
+        msg(M_USAGE, "--remote MUST be used in TCP Client mode");
+    }
+
+    if ((ce->http_proxy_options) && ce->proto != PROTO_TCP_CLIENT)
+    {
+        msg(M_USAGE, "--http-proxy MUST be used in TCP Client mode (i.e. --proto tcp-client)");
+    }
+    if ((ce->http_proxy_options) && !ce->http_proxy_options->server)
+    {
+        msg(M_USAGE, "--http-proxy not specified but other http proxy options present");
+    }
+
+    if (ce->http_proxy_options && ce->socks_proxy_server)
+    {
+        msg(M_USAGE, "--http-proxy can not be used together with --socks-proxy");
+    }
+
+    if (ce->socks_proxy_server && ce->proto == PROTO_TCP_SERVER)
+    {
+        msg(M_USAGE, "--socks-proxy can not be used in TCP Server mode");
+    }
+
+    if (ce->proto == PROTO_TCP_SERVER && (options->connection_list->len > 1))
+    {
+        msg(M_USAGE, "TCP server mode allows at most one --remote address");
+    }
+
+#if P2MP_SERVER
+
+    /*
+     * Check consistency of --mode server options.
+     */
+    if (options->mode == MODE_SERVER)
+    {
+        if (!(dev == DEV_TYPE_TUN || dev == DEV_TYPE_TAP))
+        {
+            msg(M_USAGE, "--mode server only works with --dev tun or --dev tap");
+        }
+        if (options->pull)
+        {
+            msg(M_USAGE, "--pull cannot be used with --mode server");
+        }
+        if (options->pull_filter_list)
+        {
+            msg(M_WARN, "--pull-filter ignored for --mode server");
+        }
+        if (!(proto_is_udp(ce->proto) || ce->proto == PROTO_TCP_SERVER))
+        {
+            msg(M_USAGE, "--mode server currently only supports "
+                "--proto udp or --proto tcp-server or proto tcp6-server");
+        }
+#if PORT_SHARE
+        if ((options->port_share_host || options->port_share_port)
+            && (ce->proto != PROTO_TCP_SERVER))
+        {
+            msg(M_USAGE, "--port-share only works in TCP server mode "
+                "(--proto tcp-server or tcp6-server)");
+        }
+#endif
+        if (!options->tls_server)
+        {
+            msg(M_USAGE, "--mode server requires --tls-server");
+        }
+        if (ce->remote)
+        {
+            msg(M_USAGE, "--remote cannot be used with --mode server");
+        }
+        if (!ce->bind_local)
+        {
+            msg(M_USAGE, "--nobind cannot be used with --mode server");
+        }
+        if (ce->http_proxy_options)
+        {
+            msg(M_USAGE, "--http-proxy cannot be used with --mode server");
+        }
+        if (ce->socks_proxy_server)
+        {
+            msg(M_USAGE, "--socks-proxy cannot be used with --mode server");
+        }
+        /* <connection> blocks force to have a remote embedded, so we check for the
+         * --remote and bail out if it  is present */
+        if (options->connection_list->len >1
+            || options->connection_list->array[0]->remote)
+        {
+            msg(M_USAGE, "<connection> cannot be used with --mode server");
+        }
+
+        if (options->shaper)
+        {
+            msg(M_USAGE, "--shaper cannot be used with --mode server");
+        }
+        if (options->inetd)
+        {
+            msg(M_USAGE, "--inetd cannot be used with --mode server");
+        }
+        if (options->ipchange)
+        {
+            msg(M_USAGE, "--ipchange cannot be used with --mode server (use --client-connect instead)");
+        }
+        if (!(proto_is_dgram(ce->proto) || ce->proto == PROTO_TCP_SERVER))
+        {
+            msg(M_USAGE, "--mode server currently only supports "
+                "--proto udp or --proto tcp-server or --proto tcp6-server");
+        }
+        if (!proto_is_udp(ce->proto) && (options->cf_max || options->cf_per))
+        {
+            msg(M_USAGE, "--connect-freq only works with --mode server --proto udp.  Try --max-clients instead.");
+        }
+        if (!(dev == DEV_TYPE_TAP || (dev == DEV_TYPE_TUN && options->topology == TOP_SUBNET)) && options->ifconfig_pool_netmask)
+        {
+            msg(M_USAGE, "The third parameter to --ifconfig-pool (netmask) is only valid in --dev tap mode");
+        }
+        if (options->routes && (options->routes->flags & RG_ENABLE))
+        {
+            msg(M_USAGE, "--redirect-gateway cannot be used with --mode server (however --push \"redirect-gateway\" is fine)");
+        }
+        if (options->route_delay_defined)
+        {
+            msg(M_USAGE, "--route-delay cannot be used with --mode server");
+        }
+        if (options->up_delay)
+        {
+            msg(M_USAGE, "--up-delay cannot be used with --mode server");
+        }
+        if (!options->ifconfig_pool_defined && options->ifconfig_pool_persist_filename)
+        {
+            msg(M_USAGE, "--ifconfig-pool-persist must be used with --ifconfig-pool");
+        }
+        if (options->ifconfig_ipv6_pool_defined && !options->ifconfig_ipv6_local)
+        {
+            msg(M_USAGE, "--ifconfig-ipv6-pool needs --ifconfig-ipv6");
+        }
+        if (options->allow_recursive_routing)
+        {
+            msg(M_USAGE, "--allow-recursive-routing cannot be used with --mode server");
+        }
+        if (options->auth_user_pass_file)
+        {
+            msg(M_USAGE, "--auth-user-pass cannot be used with --mode server (it should be used on the client side only)");
+        }
+        if (options->ccd_exclusive && !options->client_config_dir)
+        {
+            msg(M_USAGE, "--ccd-exclusive must be used with --client-config-dir");
+        }
+        if (options->key_method != 2)
+        {
+            msg(M_USAGE, "--mode server requires --key-method 2");
+        }
+
+        {
+            const bool ccnr = (options->auth_user_pass_verify_script
+                               || PLUGIN_OPTION_LIST(options)
+                               || MAN_CLIENT_AUTH_ENABLED(options));
+            const char *postfix = "must be used with --management-client-auth, an --auth-user-pass-verify script, or plugin";
+            if ((options->ssl_flags & (SSLF_CLIENT_CERT_NOT_REQUIRED|SSLF_CLIENT_CERT_OPTIONAL)) && !ccnr)
+            {
+                msg(M_USAGE, "--verify-client-cert none|optional %s", postfix);
+            }
+            if ((options->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) && !ccnr)
+            {
+                msg(M_USAGE, "--username-as-common-name %s", postfix);
+            }
+            if ((options->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) && !ccnr)
+            {
+                msg(M_USAGE, "--auth-user-pass-optional %s", postfix);
+            }
+        }
+    }
+    else
+    {
+        /*
+         * When not in server mode, err if parameters are
+         * specified which require --mode server.
+         */
+        if (options->ifconfig_pool_defined || options->ifconfig_pool_persist_filename)
+        {
+            msg(M_USAGE, "--ifconfig-pool/--ifconfig-pool-persist requires --mode server");
+        }
+        if (options->ifconfig_ipv6_pool_defined)
+        {
+            msg(M_USAGE, "--ifconfig-ipv6-pool requires --mode server");
+        }
+        if (options->real_hash_size != defaults.real_hash_size
+            || options->virtual_hash_size != defaults.virtual_hash_size)
+        {
+            msg(M_USAGE, "--hash-size requires --mode server");
+        }
+        if (options->learn_address_script)
+        {
+            msg(M_USAGE, "--learn-address requires --mode server");
+        }
+        if (options->client_connect_script)
+        {
+            msg(M_USAGE, "--client-connect requires --mode server");
+        }
+        if (options->client_disconnect_script)
+        {
+            msg(M_USAGE, "--client-disconnect requires --mode server");
+        }
+        if (options->client_config_dir || options->ccd_exclusive)
+        {
+            msg(M_USAGE, "--client-config-dir/--ccd-exclusive requires --mode server");
+        }
+        if (options->enable_c2c)
+        {
+            msg(M_USAGE, "--client-to-client requires --mode server");
+        }
+        if (options->duplicate_cn)
+        {
+            msg(M_USAGE, "--duplicate-cn requires --mode server");
+        }
+        if (options->cf_max || options->cf_per)
+        {
+            msg(M_USAGE, "--connect-freq requires --mode server");
+        }
+        if (options->ssl_flags & (SSLF_CLIENT_CERT_NOT_REQUIRED|SSLF_CLIENT_CERT_OPTIONAL))
+        {
+            msg(M_USAGE, "--client-cert-not-required and --verify-client-cert require --mode server");
+        }
+        if (options->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME)
+        {
+            msg(M_USAGE, "--username-as-common-name requires --mode server");
+        }
+        if (options->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL)
+        {
+            msg(M_USAGE, "--auth-user-pass-optional requires --mode server");
+        }
+        if (options->ssl_flags & SSLF_OPT_VERIFY)
+        {
+            msg(M_USAGE, "--opt-verify requires --mode server");
+        }
+        if (options->server_flags & SF_TCP_NODELAY_HELPER)
+        {
+            msg(M_WARN, "WARNING: setting tcp-nodelay on the client side will not "
+                "affect the server. To have TCP_NODELAY in both direction use "
+                "tcp-nodelay in the server configuration instead.");
+        }
+        if (options->auth_user_pass_verify_script)
+        {
+            msg(M_USAGE, "--auth-user-pass-verify requires --mode server");
+        }
+        if (options->auth_token_generate)
+        {
+            msg(M_USAGE, "--auth-gen-token requires --mode server");
+        }
+#if PORT_SHARE
+        if (options->port_share_host || options->port_share_port)
+        {
+            msg(M_USAGE, "--port-share requires TCP server mode (--mode server --proto tcp-server)");
+        }
+#endif
+
+        if (options->stale_routes_check_interval)
+        {
+            msg(M_USAGE, "--stale-routes-check requires --mode server");
+        }
+        if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NO_NAME_REMAPPING))
+        {
+            msg(M_USAGE, "--compat-x509-names no-remapping requires --mode server");
+        }
+    }
+#endif /* P2MP_SERVER */
+
+#ifdef ENABLE_CRYPTO
+
+    if (options->ncp_enabled && !tls_check_ncp_cipher_list(options->ncp_ciphers))
+    {
+        msg(M_USAGE, "NCP cipher list contains unsupported ciphers.");
+    }
+    if (options->ncp_enabled && !options->use_iv)
+    {
+        msg(M_USAGE, "--no-iv not allowed when NCP is enabled.");
+    }
+    if (!options->use_iv)
+    {
+        msg(M_WARN, "WARNING: --no-iv is deprecated and will be removed in 2.5");
+    }
+
+    if (options->keysize)
+    {
+        msg(M_WARN, "WARNING: --keysize is DEPRECATED and will be removed in OpenVPN 2.6");
+    }
+
+    if (!options->replay)
+    {
+        msg(M_WARN, "WARNING: --no-replay is DEPRECATED and will be removed in OpenVPN 2.5");
+    }
+
+    /*
+     * Check consistency of replay options
+     */
+    if (!options->replay
+        && (options->replay_window != defaults.replay_window
+            || options->replay_time != defaults.replay_time))
+    {
+        msg(M_USAGE, "--replay-window doesn't make sense when replay protection is disabled with --no-replay");
+    }
+
+    /*
+     * SSL/TLS mode sanity checks.
+     */
+    if (options->tls_server + options->tls_client
+        +(options->shared_secret_file != NULL) > 1)
+    {
+        msg(M_USAGE, "specify only one of --tls-server, --tls-client, or --secret");
+    }
+
+    if (options->ssl_flags & (SSLF_CLIENT_CERT_NOT_REQUIRED|SSLF_CLIENT_CERT_OPTIONAL))
+    {
+        msg(M_WARN, "WARNING: POTENTIALLY DANGEROUS OPTION "
+            "--verify-client-cert none|optional (or --client-cert-not-required) "
+            "may accept clients which do not present a certificate");
+    }
+
+    if (options->key_method == 1)
+    {
+        msg(M_WARN, "WARNING: --key-method 1 is deprecated and will be removed "
+            "in OpenVPN 2.5.  By default --key-method 2 will be used if not set "
+            "in the configuration file, which is the recommended approach.");
+    }
+
+    const int tls_version_max =
+        (options->ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT)
+        & SSLF_TLS_VERSION_MAX_MASK;
+    const int tls_version_min =
+        (options->ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT)
+        & SSLF_TLS_VERSION_MIN_MASK;
+
+    if (tls_version_max > 0 && tls_version_max < tls_version_min)
+    {
+        msg(M_USAGE, "--tls-version-min bigger than --tls-version-max");
+    }
+
+    if (options->tls_server || options->tls_client)
+    {
+#ifdef ENABLE_PKCS11
+        if (options->pkcs11_providers[0])
+        {
+            notnull(options->ca_file, "CA file (--ca)");
+
+            if (options->pkcs11_id_management && options->pkcs11_id != NULL)
+            {
+                msg(M_USAGE, "Parameter --pkcs11-id cannot be used when --pkcs11-id-management is also specified.");
+            }
+            if (!options->pkcs11_id_management && options->pkcs11_id == NULL)
+            {
+                msg(M_USAGE, "Parameter --pkcs11-id or --pkcs11-id-management should be specified.");
+            }
+            if (options->cert_file)
+            {
+                msg(M_USAGE, "Parameter --cert cannot be used when --pkcs11-provider is also specified.");
+            }
+            if (options->priv_key_file)
+            {
+                msg(M_USAGE, "Parameter --key cannot be used when --pkcs11-provider is also specified.");
+            }
+#ifdef MANAGMENT_EXTERNAL_KEY
+            if (options->management_flags & MF_EXTERNAL_KEY)
+            {
+                msg(M_USAGE, "Parameter --management-external-key cannot be used when --pkcs11-provider is also specified.");
+            }
+            if (options->management_flags & MF_EXTERNAL_CERT)
+            {
+                msg(M_USAGE, "Parameter --management-external-cert cannot be used when --pkcs11-provider is also specified.");
+            }
+#endif
+            if (options->pkcs12_file)
+            {
+                msg(M_USAGE, "Parameter --pkcs12 cannot be used when --pkcs11-provider is also specified.");
+            }
+#ifdef ENABLE_CRYPTOAPI
+            if (options->cryptoapi_cert)
+            {
+                msg(M_USAGE, "Parameter --cryptoapicert cannot be used when --pkcs11-provider is also specified.");
+            }
+#endif
+        }
+        else
+#endif /* ifdef ENABLE_PKCS11 */
+#ifdef MANAGMENT_EXTERNAL_KEY
+        if ((options->management_flags & MF_EXTERNAL_KEY) && options->priv_key_file)
+        {
+            msg(M_USAGE, "--key and --management-external-key are mutually exclusive");
+        }
+        else if ((options->management_flags & MF_EXTERNAL_CERT))
+        {
+            if (options->cert_file)
+            {
+                msg(M_USAGE, "--cert and --management-external-cert are mutually exclusive");
+            }
+            else if (!(options->management_flags & MF_EXTERNAL_KEY))
+            {
+                msg(M_USAGE, "--management-external-cert must be used with --management-external-key");
+            }
+        }
+        else
+#endif
+#ifdef ENABLE_CRYPTOAPI
+        if (options->cryptoapi_cert)
+        {
+            if ((!(options->ca_file)) && (!(options->ca_path)))
+            {
+                msg(M_USAGE, "You must define CA file (--ca) or CA path (--capath)");
+            }
+            if (options->cert_file)
+            {
+                msg(M_USAGE, "Parameter --cert cannot be used when --cryptoapicert is also specified.");
+            }
+            if (options->priv_key_file)
+            {
+                msg(M_USAGE, "Parameter --key cannot be used when --cryptoapicert is also specified.");
+            }
+            if (options->pkcs12_file)
+            {
+                msg(M_USAGE, "Parameter --pkcs12 cannot be used when --cryptoapicert is also specified.");
+            }
+#ifdef MANAGMENT_EXTERNAL_KEY
+            if (options->management_flags & MF_EXTERNAL_KEY)
+            {
+                msg(M_USAGE, "Parameter --management-external-key cannot be used when --cryptoapicert is also specified.");
+            }
+            if (options->management_flags & MF_EXTERNAL_CERT)
+            {
+                msg(M_USAGE, "Parameter --management-external-cert cannot be used when --cryptoapicert is also specified.");
+            }
+#endif
+        }
+        else
+#endif /* ifdef ENABLE_CRYPTOAPI */
+        if (options->pkcs12_file)
+        {
+#ifdef ENABLE_CRYPTO_MBEDTLS
+            msg(M_USAGE, "Parameter --pkcs12 cannot be used with the mbed TLS version version of OpenVPN.");
+#else
+            if (options->ca_path)
+            {
+                msg(M_USAGE, "Parameter --capath cannot be used when --pkcs12 is also specified.");
+            }
+            if (options->cert_file)
+            {
+                msg(M_USAGE, "Parameter --cert cannot be used when --pkcs12 is also specified.");
+            }
+            if (options->priv_key_file)
+            {
+                msg(M_USAGE, "Parameter --key cannot be used when --pkcs12 is also specified.");
+            }
+#ifdef MANAGMENT_EXTERNAL_KEY
+            if (options->management_flags & MF_EXTERNAL_KEY)
+            {
+                msg(M_USAGE, "Parameter --management-external-key cannot be used when --pkcs12 is also specified.");
+            }
+            if (options->management_flags & MF_EXTERNAL_CERT)
+            {
+                msg(M_USAGE, "Parameter --management-external-cert cannot be used when --pkcs12 is also specified.");
+            }
+#endif
+#endif /* ifdef ENABLE_CRYPTO_MBEDTLS */
+        }
+        else
+        {
+#ifdef ENABLE_CRYPTO_MBEDTLS
+            if (!(options->ca_file))
+            {
+                msg(M_USAGE, "You must define CA file (--ca)");
+            }
+            if (options->ca_path)
+            {
+                msg(M_USAGE, "Parameter --capath cannot be used with the mbed TLS version version of OpenVPN.");
+            }
+#else  /* ifdef ENABLE_CRYPTO_MBEDTLS */
+            if ((!(options->ca_file)) && (!(options->ca_path)))
+            {
+                msg(M_USAGE, "You must define CA file (--ca) or CA path (--capath)");
+            }
+#endif
+            if (pull)
+            {
+
+                const int sum =
+#ifdef MANAGMENT_EXTERNAL_KEY
+                    ((options->cert_file != NULL) || (options->management_flags & MF_EXTERNAL_CERT))
+                    +((options->priv_key_file != NULL) || (options->management_flags & MF_EXTERNAL_KEY));
+#else
+                    (options->cert_file != NULL) + (options->priv_key_file != NULL);
+#endif
+
+                if (sum == 0)
+                {
+#if P2MP
+                    if (!options->auth_user_pass_file)
+#endif
+                    msg(M_USAGE, "No client-side authentication method is specified.  You must use either --cert/--key, --pkcs12, or --auth-user-pass");
+                }
+                else if (sum == 2)
+                {
+                }
+                else
+                {
+                    msg(M_USAGE, "If you use one of --cert or --key, you must use them both");
+                }
+            }
+            else
+            {
+#ifdef MANAGMENT_EXTERNAL_KEY
+                if (!(options->management_flags & MF_EXTERNAL_CERT))
+#endif
+                notnull(options->cert_file, "certificate file (--cert) or PKCS#12 file (--pkcs12)");
+#ifdef MANAGMENT_EXTERNAL_KEY
+                if (!(options->management_flags & MF_EXTERNAL_KEY))
+#endif
+                notnull(options->priv_key_file, "private key file (--key) or PKCS#12 file (--pkcs12)");
+            }
+        }
+        if (options->tls_auth_file && options->tls_crypt_file)
+        {
+            msg(M_USAGE, "--tls-auth and --tls-crypt are mutually exclusive");
+        }
+    }
+    else
+    {
+        /*
+         * Make sure user doesn't specify any TLS options
+         * when in non-TLS mode.
+         */
+
+#define MUST_BE_UNDEF(parm) if (options->parm != defaults.parm) {msg(M_USAGE, err, #parm); \
+}
+
+        const char err[] = "Parameter %s can only be specified in TLS-mode, i.e. where --tls-server or --tls-client is also specified.";
+
+        MUST_BE_UNDEF(ca_file);
+        MUST_BE_UNDEF(ca_path);
+        MUST_BE_UNDEF(dh_file);
+        MUST_BE_UNDEF(cert_file);
+        MUST_BE_UNDEF(priv_key_file);
+#ifndef ENABLE_CRYPTO_MBEDTLS
+        MUST_BE_UNDEF(pkcs12_file);
+#endif
+        MUST_BE_UNDEF(cipher_list);
+        MUST_BE_UNDEF(cipher_list_tls13);
+        MUST_BE_UNDEF(tls_cert_profile);
+        MUST_BE_UNDEF(tls_verify);
+        MUST_BE_UNDEF(tls_export_cert);
+        MUST_BE_UNDEF(verify_x509_name);
+        MUST_BE_UNDEF(tls_timeout);
+        MUST_BE_UNDEF(renegotiate_bytes);
+        MUST_BE_UNDEF(renegotiate_packets);
+        MUST_BE_UNDEF(renegotiate_seconds);
+        MUST_BE_UNDEF(handshake_window);
+        MUST_BE_UNDEF(transition_window);
+        MUST_BE_UNDEF(tls_auth_file);
+        MUST_BE_UNDEF(tls_crypt_file);
+        MUST_BE_UNDEF(single_session);
+#ifdef ENABLE_PUSH_PEER_INFO
+        MUST_BE_UNDEF(push_peer_info);
+#endif
+        MUST_BE_UNDEF(tls_exit);
+        MUST_BE_UNDEF(crl_file);
+        MUST_BE_UNDEF(key_method);
+        MUST_BE_UNDEF(ns_cert_type);
+        MUST_BE_UNDEF(remote_cert_ku[0]);
+        MUST_BE_UNDEF(remote_cert_eku);
+#ifdef ENABLE_PKCS11
+        MUST_BE_UNDEF(pkcs11_providers[0]);
+        MUST_BE_UNDEF(pkcs11_private_mode[0]);
+        MUST_BE_UNDEF(pkcs11_id);
+        MUST_BE_UNDEF(pkcs11_id_management);
+#endif
+
+        if (pull)
+        {
+            msg(M_USAGE, err, "--pull");
+        }
+    }
+#undef MUST_BE_UNDEF
+#endif /* ENABLE_CRYPTO */
+
+#if P2MP
+    if (options->auth_user_pass_file && !options->pull)
+    {
+        msg(M_USAGE, "--auth-user-pass requires --pull");
+    }
+#endif
+
+    uninit_options(&defaults);
+}
+
+static void
+options_postprocess_mutate_ce(struct options *o, struct connection_entry *ce)
+{
+    const int dev = dev_type_enum(o->dev, o->dev_type);
+
+#if P2MP_SERVER
+    if (o->server_defined || o->server_bridge_defined || o->server_bridge_proxy_dhcp)
+    {
+        if (ce->proto == PROTO_TCP)
+        {
+            ce->proto = PROTO_TCP_SERVER;
+        }
+    }
+#endif
+#if P2MP
+    if (o->client)
+    {
+        if (ce->proto == PROTO_TCP)
+        {
+            ce->proto = PROTO_TCP_CLIENT;
+        }
+    }
+#endif
+
+    if (ce->proto == PROTO_TCP_CLIENT && !ce->local && !ce->local_port_defined && !ce->bind_defined)
+    {
+        ce->bind_local = false;
+    }
+
+    if (ce->proto == PROTO_UDP && ce->socks_proxy_server && !ce->local && !ce->local_port_defined && !ce->bind_defined)
+    {
+        ce->bind_local = false;
+    }
+
+    if (!ce->bind_local)
+    {
+        ce->local_port = NULL;
+    }
+
+    /* if protocol forcing is enabled, disable all protocols except for the forced one */
+    if (o->proto_force >= 0 && o->proto_force != ce->proto)
+    {
+        ce->flags |= CE_DISABLED;
+    }
+
+    /*
+     * If --mssfix is supplied without a parameter, default
+     * it to --fragment value, if --fragment is specified.
+     */
+    if (o->ce.mssfix_default)
+    {
+#ifdef ENABLE_FRAGMENT
+        if (ce->fragment)
+        {
+            ce->mssfix = ce->fragment;
+        }
+#else
+        msg(M_USAGE, "--mssfix must specify a parameter");
+#endif
+    }
+
+    /* our socks code is not fully IPv6 enabled yet (TCP works, UDP not)
+     * so fall back to IPv4-only (trac #1221)
+     */
+    if (ce->socks_proxy_server && proto_is_udp(ce->proto) && ce->af != AF_INET)
+    {
+        if (ce->af == AF_INET6)
+        {
+            msg(M_INFO, "WARNING: '--proto udp6' is not compatible with "
+                "'--socks-proxy' today.  Forcing IPv4 mode." );
+        }
+        else
+        {
+            msg(M_INFO, "NOTICE: dual-stack mode for '--proto udp' does not "
+                "work correctly with '--socks-proxy' today.  Forcing IPv4." );
+        }
+        ce->af = AF_INET;
+    }
+
+    /*
+     * Set MTU defaults
+     */
+    {
+        if (!ce->tun_mtu_defined && !ce->link_mtu_defined)
+        {
+            ce->tun_mtu_defined = true;
+        }
+        if ((dev == DEV_TYPE_TAP) && !ce->tun_mtu_extra_defined)
+        {
+            ce->tun_mtu_extra_defined = true;
+            ce->tun_mtu_extra = TAP_MTU_EXTRA_DEFAULT;
+        }
+    }
+
+}
+
+#ifdef _WIN32
+/* If iservice is in use, we need def1 method for redirect-gateway */
+static void
+remap_redirect_gateway_flags(struct options *opt)
+{
+    if (opt->routes
+        && opt->route_method == ROUTE_METHOD_SERVICE
+        && opt->routes->flags & RG_REROUTE_GW
+        && !(opt->routes->flags & RG_DEF1))
+    {
+        msg(M_INFO, "Flag 'def1' added to --redirect-gateway (iservice is in use)");
+        opt->routes->flags |= RG_DEF1;
+    }
+}
+#endif
+
+static void
+options_postprocess_mutate_invariant(struct options *options)
+{
+#ifdef _WIN32
+    const int dev = dev_type_enum(options->dev, options->dev_type);
+#endif
+
+    /*
+     * In forking TCP server mode, you don't need to ifconfig
+     * the tap device (the assumption is that it will be bridged).
+     */
+    if (options->inetd == INETD_NOWAIT)
+    {
+        options->ifconfig_noexec = true;
+    }
+
+#ifdef _WIN32
+    if ((dev == DEV_TYPE_TUN || dev == DEV_TYPE_TAP) && !options->route_delay_defined)
+    {
+        if (options->mode == MODE_POINT_TO_POINT)
+        {
+            options->route_delay_defined = true;
+            options->route_delay = 5; /* Vista sometimes has a race without this */
+        }
+    }
+
+    if (options->ifconfig_noexec)
+    {
+        options->tuntap_options.ip_win32_type = IPW32_SET_MANUAL;
+        options->ifconfig_noexec = false;
+    }
+
+    remap_redirect_gateway_flags(options);
+#endif
+
+#if P2MP_SERVER
+    /*
+     * Check consistency of --mode server options.
+     */
+    if (options->mode == MODE_SERVER)
+    {
+#ifdef _WIN32
+        /*
+         * We need to explicitly set --tap-sleep because
+         * we do not schedule event timers in the top-level context.
+         */
+        options->tuntap_options.tap_sleep = 10;
+        if (options->route_delay_defined && options->route_delay)
+        {
+            options->tuntap_options.tap_sleep = options->route_delay;
+        }
+        options->route_delay_defined = false;
+#endif
+    }
+#endif
+
+#ifdef DEFAULT_PKCS11_MODULE
+    /* If p11-kit is present on the system then load its p11-kit-proxy.so
+     * by default if the user asks for PKCS#11 without otherwise specifying
+     * the module to use. */
+    if (!options->pkcs11_providers[0]
+        && (options->pkcs11_id || options->pkcs11_id_management))
+    {
+        options->pkcs11_providers[0] = DEFAULT_PKCS11_MODULE;
+    }
+#endif
+}
+
+static void
+options_postprocess_verify(const struct options *o)
+{
+    if (o->connection_list)
+    {
+        int i;
+        for (i = 0; i < o->connection_list->len; ++i)
+        {
+            options_postprocess_verify_ce(o, o->connection_list->array[i]);
+        }
+    }
+    else
+    {
+        options_postprocess_verify_ce(o, &o->ce);
+    }
+}
+
+static void
+options_postprocess_mutate(struct options *o)
+{
+    int i;
+    /*
+     * Process helper-type options which map to other, more complex
+     * sequences of options.
+     */
+    helper_client_server(o);
+    helper_keepalive(o);
+    helper_tcp_nodelay(o);
+
+    options_postprocess_mutate_invariant(o);
+
+    if (o->remote_list && !o->connection_list)
+    {
+        /*
+         * Convert remotes into connection list
+         */
+        const struct remote_list *rl = o->remote_list;
+        for (i = 0; i < rl->len; ++i)
+        {
+            const struct remote_entry *re = rl->array[i];
+            struct connection_entry ce = o->ce;
+            struct connection_entry *ace;
+
+            ASSERT(re->remote);
+            connection_entry_load_re(&ce, re);
+            ace = alloc_connection_entry(o, M_USAGE);
+            ASSERT(ace);
+            *ace = ce;
+        }
+    }
+    else if (!o->remote_list && !o->connection_list)
+    {
+        struct connection_entry *ace;
+        ace = alloc_connection_entry(o, M_USAGE);
+        ASSERT(ace);
+        *ace = o->ce;
+    }
+
+    ASSERT(o->connection_list);
+    for (i = 0; i < o->connection_list->len; ++i)
+    {
+        options_postprocess_mutate_ce(o, o->connection_list->array[i]);
+    }
+
+#ifdef ENABLE_CRYPTO
+    if (o->tls_server)
+    {
+        /* Check that DH file is specified, or explicitly disabled */
+        notnull(o->dh_file, "DH file (--dh)");
+        if (streq(o->dh_file, "none"))
+        {
+            o->dh_file = NULL;
+        }
+    }
+    else if (o->dh_file)
+    {
+        /* DH file is only meaningful in a tls-server context. */
+        msg(M_WARN, "WARNING: Ignoring option 'dh' in tls-client mode, please only "
+                    "include this in your server configuration");
+        o->dh_file = NULL;
+    }
+
+    /* cipher negotiation (NCP) currently assumes --pull or --mode server */
+    if (o->ncp_enabled
+        && !(o->pull || o->mode == MODE_SERVER) )
+    {
+        msg( M_WARN, "disabling NCP mode (--ncp-disable) because not "
+             "in P2MP client or server mode" );
+        o->ncp_enabled = false;
+    }
+#endif
+
+#if ENABLE_MANAGEMENT
+    if (o->http_proxy_override)
+    {
+        options_postprocess_http_proxy_override(o);
+    }
+#endif
+
+#if P2MP
+    /*
+     * Save certain parms before modifying options via --pull
+     */
+    pre_pull_save(o);
+#endif
+}
+
+/*
+ *  Check file/directory sanity
+ *
+ */
+#ifndef ENABLE_SMALL  /** Expect people using the stripped down version to know what they do */
+
+#define CHKACC_FILE (1<<0)       /** Check for a file/directory precense */
+#define CHKACC_DIRPATH (1<<1)    /** Check for directory precense where a file should reside */
+#define CHKACC_FILEXSTWR (1<<2)  /** If file exists, is it writable? */
+#define CHKACC_INLINE (1<<3)     /** File is present if it's an inline file */
+#define CHKACC_ACPTSTDIN (1<<4)  /** If filename is stdin, it's allowed and "exists" */
+#define CHKACC_PRIVATE (1<<5)    /** Warn if this (private) file is group/others accessible */
+
+static bool
+check_file_access(const int type, const char *file, const int mode, const char *opt)
+{
+    int errcode = 0;
+
+    /* If no file configured, no errors to look for */
+    if (!file)
+    {
+        return false;
+    }
+
+    /* If this may be an inline file, and the proper inline "filename" is set - no issues */
+    if ((type & CHKACC_INLINE) && streq(file, INLINE_FILE_TAG) )
+    {
+        return false;
+    }
+
+    /* If stdin is allowed and the file name is 'stdin', then do no
+     * further checks as stdin is always available
+     */
+    if ( (type & CHKACC_ACPTSTDIN) && streq(file, "stdin") )
+    {
+        return false;
+    }
+
+    /* Is the directory path leading to the given file accessible? */
+    if (type & CHKACC_DIRPATH)
+    {
+        char *fullpath = string_alloc(file, NULL); /* POSIX dirname() implementaion may modify its arguments */
+        char *dirpath = dirname(fullpath);
+
+        if (platform_access(dirpath, mode|X_OK) != 0)
+        {
+            errcode = errno;
+        }
+        free(fullpath);
+    }
+
+    /* Is the file itself accessible? */
+    if (!errcode && (type & CHKACC_FILE) && (platform_access(file, mode) != 0) )
+    {
+        errcode = errno;
+    }
+
+    /* If the file exists and is accessible, is it writable? */
+    if (!errcode && (type & CHKACC_FILEXSTWR) && (platform_access(file, F_OK) == 0) )
+    {
+        if (platform_access(file, W_OK) != 0)
+        {
+            errcode = errno;
+        }
+    }
+
+    /* Warn if a given private file is group/others accessible. */
+    if (type & CHKACC_PRIVATE)
+    {
+        platform_stat_t st;
+        if (platform_stat(file, &st))
+        {
+            msg(M_WARN | M_ERRNO, "WARNING: cannot stat file '%s'", file);
+        }
+#ifndef _WIN32
+        else
+        {
+            if (st.st_mode & (S_IRWXG|S_IRWXO))
+            {
+                msg(M_WARN, "WARNING: file '%s' is group or others accessible", file);
+            }
+        }
+#endif
+    }
+
+    /* Scream if an error is found */
+    if (errcode > 0)
+    {
+        msg(M_NOPREFIX | M_OPTERR | M_ERRNO, "%s fails with '%s'", opt, file);
+    }
+
+    /* Return true if an error occured */
+    return (errcode != 0 ? true : false);
+}
+
+/* A wrapper for check_file_access() which also takes a chroot directory.
+ * If chroot is NULL, behaviour is exactly the same as calling check_file_access() directly,
+ * otherwise it will look for the file inside the given chroot directory instead.
+ */
+static bool
+check_file_access_chroot(const char *chroot, const int type, const char *file, const int mode, const char *opt)
+{
+    bool ret = false;
+
+    /* If no file configured, no errors to look for */
+    if (!file)
+    {
+        return false;
+    }
+
+    /* If chroot is set, look for the file/directory inside the chroot */
+    if (chroot)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer chroot_file;
+        int len = 0;
+
+        /* Build up a new full path including chroot directory */
+        len = strlen(chroot) + strlen(PATH_SEPARATOR_STR) + strlen(file) + 1;
+        chroot_file = alloc_buf_gc(len, &gc);
+        buf_printf(&chroot_file, "%s%s%s", chroot, PATH_SEPARATOR_STR, file);
+        ASSERT(chroot_file.len > 0);
+
+        ret = check_file_access(type, BSTR(&chroot_file), mode, opt);
+        gc_free(&gc);
+    }
+    else
+    {
+        /* No chroot in play, just call core file check function */
+        ret = check_file_access(type, file, mode, opt);
+    }
+    return ret;
+}
+
+
+/*
+ * Verifies that the path in the "command" that comes after certain script options (e.g., --up) is a
+ * valid file with appropriate permissions.
+ *
+ * "command" consists of a path, optionally followed by a space, which may be
+ * followed by arbitrary arguments. It is NOT a full shell command line -- shell expansion is not
+ * performed.
+ *
+ * The path and arguments in "command" may be single- or double-quoted or escaped.
+ *
+ * The path is extracted from "command", then check_file_access() is called to check it. The
+ * arguments, if any, are ignored.
+ *
+ * Note that the type, mode, and opt arguments to this routine are the same as the corresponding
+ * check_file_access() arguments.
+ */
+static bool
+check_cmd_access(const char *command, const char *opt, const char *chroot)
+{
+    struct argv argv;
+    bool return_code;
+
+    /* If no command was set, there are no errors to look for */
+    if (!command)
+    {
+        return false;
+    }
+
+    /* Extract executable path and arguments */
+    argv = argv_new();
+    argv_parse_cmd(&argv, command);
+
+    /* if an executable is specified then check it; otherwise, complain */
+    if (argv.argv[0])
+    {
+        /* Scripts requires R_OK as well, but that might fail on binaries which
+         * only requires X_OK to function on Unix - a scenario not unlikely to
+         * be seen on suid binaries.
+         */
+        return_code = check_file_access_chroot(chroot, CHKACC_FILE, argv.argv[0], X_OK, opt);
+    }
+    else
+    {
+        msg(M_NOPREFIX|M_OPTERR, "%s fails with '%s': No path to executable.",
+            opt, command);
+        return_code = true;
+    }
+
+    argv_reset(&argv);
+
+    return return_code;
+}
+
+/*
+ * Sanity check of all file/dir options.  Checks that file/dir
+ * is accessible by OpenVPN
+ */
+static void
+options_postprocess_filechecks(struct options *options)
+{
+    bool errs = false;
+
+#ifdef ENABLE_CRYPTO
+    /* ** SSL/TLS/crypto related files ** */
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE, options->dh_file, R_OK, "--dh");
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE, options->ca_file, R_OK, "--ca");
+    errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE, options->ca_path, R_OK, "--capath");
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE, options->cert_file, R_OK, "--cert");
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE, options->extra_certs_file, R_OK,
+                              "--extra-certs");
+#ifdef MANAGMENT_EXTERNAL_KEY
+    if (!(options->management_flags & MF_EXTERNAL_KEY))
+#endif
+    {
+        errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE|CHKACC_PRIVATE,
+                                  options->priv_key_file, R_OK, "--key");
+    }
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE|CHKACC_PRIVATE,
+                              options->pkcs12_file, R_OK, "--pkcs12");
+
+    if (options->ssl_flags & SSLF_CRL_VERIFY_DIR)
+    {
+        errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE, options->crl_file, R_OK|X_OK,
+                                         "--crl-verify directory");
+    }
+    else
+    {
+        errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE|CHKACC_INLINE,
+                                         options->crl_file, R_OK, "--crl-verify");
+    }
+
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE|CHKACC_PRIVATE,
+                              options->tls_auth_file, R_OK, "--tls-auth");
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE|CHKACC_PRIVATE,
+                              options->tls_crypt_file, R_OK, "--tls-crypt");
+    errs |= check_file_access(CHKACC_FILE|CHKACC_INLINE|CHKACC_PRIVATE,
+                              options->shared_secret_file, R_OK, "--secret");
+    errs |= check_file_access(CHKACC_DIRPATH|CHKACC_FILEXSTWR,
+                              options->packet_id_file, R_OK|W_OK, "--replay-persist");
+
+    /* ** Password files ** */
+    errs |= check_file_access(CHKACC_FILE|CHKACC_ACPTSTDIN|CHKACC_PRIVATE,
+                              options->key_pass_file, R_OK, "--askpass");
+#endif /* ENABLE_CRYPTO */
+#ifdef ENABLE_MANAGEMENT
+    errs |= check_file_access(CHKACC_FILE|CHKACC_ACPTSTDIN|CHKACC_PRIVATE,
+                              options->management_user_pass, R_OK,
+                              "--management user/password file");
+#endif /* ENABLE_MANAGEMENT */
+#if P2MP
+    errs |= check_file_access(CHKACC_FILE|CHKACC_ACPTSTDIN|CHKACC_PRIVATE,
+                              options->auth_user_pass_file, R_OK,
+                              "--auth-user-pass");
+#endif /* P2MP */
+
+    /* ** System related ** */
+    errs |= check_file_access(CHKACC_FILE, options->chroot_dir,
+                              R_OK|X_OK, "--chroot directory");
+    errs |= check_file_access(CHKACC_DIRPATH|CHKACC_FILEXSTWR, options->writepid,
+                              R_OK|W_OK, "--writepid");
+
+    /* ** Log related ** */
+    errs |= check_file_access(CHKACC_DIRPATH|CHKACC_FILEXSTWR, options->status_file,
+                              R_OK|W_OK, "--status");
+
+    /* ** Config related ** */
+#ifdef ENABLE_CRYPTO
+    errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE, options->tls_export_cert,
+                                     R_OK|W_OK|X_OK, "--tls-export-cert");
+#endif /* ENABLE_CRYPTO */
+#if P2MP_SERVER
+    errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE, options->client_config_dir,
+                                     R_OK|X_OK, "--client-config-dir");
+    errs |= check_file_access_chroot(options->chroot_dir, CHKACC_FILE, options->tmp_dir,
+                                     R_OK|W_OK|X_OK, "Temporary directory (--tmp-dir)");
+
+#endif /* P2MP_SERVER */
+
+    if (errs)
+    {
+        msg(M_USAGE, "Please correct these errors.");
+    }
+}
+#endif /* !ENABLE_SMALL */
+
+/*
+ * Sanity check on options.
+ * Also set some options based on other
+ * options.
+ */
+void
+options_postprocess(struct options *options)
+{
+    options_postprocess_mutate(options);
+    options_postprocess_verify(options);
+#ifndef ENABLE_SMALL
+    options_postprocess_filechecks(options);
+#endif /* !ENABLE_SMALL */
+}
+
+#if P2MP
+
+/*
+ * Save/Restore certain option defaults before --pull is applied.
+ */
+
+void
+pre_pull_save(struct options *o)
+{
+    if (o->pull)
+    {
+        ALLOC_OBJ_CLEAR_GC(o->pre_pull, struct options_pre_pull, &o->gc);
+        o->pre_pull->tuntap_options = o->tuntap_options;
+        o->pre_pull->tuntap_options_defined = true;
+        o->pre_pull->foreign_option_index = o->foreign_option_index;
+        if (o->routes)
+        {
+            o->pre_pull->routes = clone_route_option_list(o->routes, &o->gc);
+            o->pre_pull->routes_defined = true;
+        }
+        if (o->routes_ipv6)
+        {
+            o->pre_pull->routes_ipv6 = clone_route_ipv6_option_list(o->routes_ipv6, &o->gc);
+            o->pre_pull->routes_ipv6_defined = true;
+        }
+        if (o->client_nat)
+        {
+            o->pre_pull->client_nat = clone_client_nat_option_list(o->client_nat, &o->gc);
+            o->pre_pull->client_nat_defined = true;
+        }
+    }
+}
+
+void
+pre_pull_restore(struct options *o, struct gc_arena *gc)
+{
+    const struct options_pre_pull *pp = o->pre_pull;
+    if (pp)
+    {
+        CLEAR(o->tuntap_options);
+        if (pp->tuntap_options_defined)
+        {
+            o->tuntap_options = pp->tuntap_options;
+        }
+
+        if (pp->routes_defined)
+        {
+            rol_check_alloc(o);
+            copy_route_option_list(o->routes, pp->routes, gc);
+        }
+        else
+        {
+            o->routes = NULL;
+        }
+
+        if (pp->routes_ipv6_defined)
+        {
+            rol6_check_alloc(o);
+            copy_route_ipv6_option_list(o->routes_ipv6, pp->routes_ipv6, gc);
+        }
+        else
+        {
+            o->routes_ipv6 = NULL;
+        }
+
+        if (pp->client_nat_defined)
+        {
+            cnol_check_alloc(o);
+            copy_client_nat_option_list(o->client_nat, pp->client_nat);
+        }
+        else
+        {
+            o->client_nat = NULL;
+        }
+
+        o->foreign_option_index = pp->foreign_option_index;
+    }
+
+    o->push_continuation = 0;
+    o->push_option_types_found = 0;
+}
+
+#endif /* if P2MP */
+
+#ifdef ENABLE_OCC
+
+/**
+ * Calculate the link-mtu to advertise to our peer.  The actual value is not
+ * relevant, because we will possibly perform data channel cipher negotiation
+ * after this, but older clients will log warnings if we do not supply them the
+ * value they expect.  This assumes that the traditional cipher/auth directives
+ * in the config match the config of the peer.
+ */
+static size_t
+calc_options_string_link_mtu(const struct options *o, const struct frame *frame)
+{
+    size_t link_mtu = EXPANDED_SIZE(frame);
+#ifdef ENABLE_CRYPTO
+    if (o->pull || o->mode == MODE_SERVER)
+    {
+        struct frame fake_frame = *frame;
+        struct key_type fake_kt;
+        init_key_type(&fake_kt, o->ciphername, o->authname, o->keysize, true,
+                      false);
+        frame_remove_from_extra_frame(&fake_frame, crypto_max_overhead());
+        crypto_adjust_frame_parameters(&fake_frame, &fake_kt, o->use_iv,
+                                       o->replay, cipher_kt_mode_ofb_cfb(fake_kt.cipher));
+        frame_finalize(&fake_frame, o->ce.link_mtu_defined, o->ce.link_mtu,
+                       o->ce.tun_mtu_defined, o->ce.tun_mtu);
+        msg(D_MTU_DEBUG, "%s: link-mtu %u -> %d", __func__, (unsigned int) link_mtu,
+            EXPANDED_SIZE(&fake_frame));
+        link_mtu = EXPANDED_SIZE(&fake_frame);
+    }
+#endif
+    return link_mtu;
+}
+
+/*
+ * Build an options string to represent data channel encryption options.
+ * This string must match exactly between peers.  The keysize is checked
+ * separately by read_key().
+ *
+ * The following options must match on both peers:
+ *
+ * Tunnel options:
+ *
+ * --dev tun|tap [unit number need not match]
+ * --dev-type tun|tap
+ * --link-mtu
+ * --udp-mtu
+ * --tun-mtu
+ * --proto udp
+ * --proto tcp-client [matched with --proto tcp-server
+ *                     on the other end of the connection]
+ * --proto tcp-server [matched with --proto tcp-client on
+ *                     the other end of the connection]
+ * --tun-ipv6
+ * --ifconfig x y [matched with --ifconfig y x on
+ *                 the other end of the connection]
+ *
+ * --comp-lzo
+ * --compress alg
+ * --fragment
+ *
+ * Crypto Options:
+ *
+ * --cipher
+ * --auth
+ * --keysize
+ * --secret
+ * --no-replay
+ * --no-iv
+ *
+ * SSL Options:
+ *
+ * --tls-auth
+ * --tls-client [matched with --tls-server on
+ *               the other end of the connection]
+ * --tls-server [matched with --tls-client on
+ *               the other end of the connection]
+ */
+char *
+options_string(const struct options *o,
+               const struct frame *frame,
+               struct tuntap *tt,
+               bool remote,
+               struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf(OPTION_LINE_SIZE);
+    bool tt_local = false;
+
+    buf_printf(&out, "V4");
+
+    /*
+     * Tunnel Options
+     */
+
+    buf_printf(&out, ",dev-type %s", dev_type_string(o->dev, o->dev_type));
+    buf_printf(&out, ",link-mtu %u", (unsigned int) calc_options_string_link_mtu(o, frame));
+    buf_printf(&out, ",tun-mtu %d", PAYLOAD_SIZE(frame));
+    buf_printf(&out, ",proto %s",  proto_remote(o->ce.proto, remote));
+
+    /* send tun_ipv6 only in peer2peer mode - in client/server mode, it
+     * is usually pushed by the server, triggering a non-helpful warning
+     */
+    if (o->ifconfig_ipv6_local && o->mode == MODE_POINT_TO_POINT && !PULL_DEFINED(o))
+    {
+        buf_printf(&out, ",tun-ipv6");
+    }
+
+    /*
+     * Try to get ifconfig parameters into the options string.
+     * If tt is undefined, make a temporary instantiation.
+     */
+    if (!tt)
+    {
+        tt = init_tun(o->dev,
+                      o->dev_type,
+                      o->topology,
+                      o->ifconfig_local,
+                      o->ifconfig_remote_netmask,
+                      o->ifconfig_ipv6_local,
+                      o->ifconfig_ipv6_netbits,
+                      o->ifconfig_ipv6_remote,
+                      NULL,
+                      NULL,
+                      false,
+                      NULL);
+        if (tt)
+        {
+            tt_local = true;
+        }
+    }
+
+    if (tt && o->mode == MODE_POINT_TO_POINT && !PULL_DEFINED(o))
+    {
+        const char *ios = ifconfig_options_string(tt, remote, o->ifconfig_nowarn, gc);
+        if (ios && strlen(ios))
+        {
+            buf_printf(&out, ",ifconfig %s", ios);
+        }
+    }
+    if (tt_local)
+    {
+        free(tt);
+        tt = NULL;
+    }
+
+#ifdef USE_COMP
+    if (o->comp.alg != COMP_ALG_UNDEF)
+    {
+        buf_printf(&out, ",comp-lzo"); /* for compatibility, this simply indicates that compression context is active, not necessarily LZO per-se */
+    }
+#endif
+
+#ifdef ENABLE_FRAGMENT
+    if (o->ce.fragment)
+    {
+        buf_printf(&out, ",mtu-dynamic");
+    }
+#endif
+
+#ifdef ENABLE_CRYPTO
+
+#define TLS_CLIENT (o->tls_client)
+#define TLS_SERVER (o->tls_server)
+
+    /*
+     * Key direction
+     */
+    {
+        const char *kd = keydirection2ascii(o->key_direction, remote, false);
+        if (kd)
+        {
+            buf_printf(&out, ",keydir %s", kd);
+        }
+    }
+
+    /*
+     * Crypto Options
+     */
+    if (o->shared_secret_file || TLS_CLIENT || TLS_SERVER)
+    {
+        struct key_type kt;
+
+        ASSERT((o->shared_secret_file != NULL)
+               + (TLS_CLIENT == true)
+               + (TLS_SERVER == true)
+               <= 1);
+
+        init_key_type(&kt, o->ciphername, o->authname, o->keysize, true,
+                      false);
+
+        buf_printf(&out, ",cipher %s",
+                   translate_cipher_name_to_openvpn(cipher_kt_name(kt.cipher)));
+        buf_printf(&out, ",auth %s", md_kt_name(kt.digest));
+        buf_printf(&out, ",keysize %d", kt.cipher_length * 8);
+        if (o->shared_secret_file)
+        {
+            buf_printf(&out, ",secret");
+        }
+        if (!o->replay)
+        {
+            buf_printf(&out, ",no-replay");
+        }
+        if (!o->use_iv)
+        {
+            buf_printf(&out, ",no-iv");
+        }
+
+#ifdef ENABLE_PREDICTION_RESISTANCE
+        if (o->use_prediction_resistance)
+        {
+            buf_printf(&out, ",use-prediction-resistance");
+        }
+#endif
+    }
+
+    /*
+     * SSL Options
+     */
+    {
+        if (TLS_CLIENT || TLS_SERVER)
+        {
+            if (o->tls_auth_file)
+            {
+                buf_printf(&out, ",tls-auth");
+            }
+            /* Not adding tls-crypt here, because we won't reach this code if
+             * tls-auth/tls-crypt does not match.  Removing tls-auth here would
+             * break stuff, so leaving that in place. */
+
+            if (o->key_method > 1)
+            {
+                buf_printf(&out, ",key-method %d", o->key_method);
+            }
+        }
+
+        if (remote)
+        {
+            if (TLS_CLIENT)
+            {
+                buf_printf(&out, ",tls-server");
+            }
+            else if (TLS_SERVER)
+            {
+                buf_printf(&out, ",tls-client");
+            }
+        }
+        else
+        {
+            if (TLS_CLIENT)
+            {
+                buf_printf(&out, ",tls-client");
+            }
+            else if (TLS_SERVER)
+            {
+                buf_printf(&out, ",tls-server");
+            }
+        }
+    }
+
+#undef TLS_CLIENT
+#undef TLS_SERVER
+
+#endif /* ENABLE_CRYPTO */
+
+    return BSTR(&out);
+}
+
+/*
+ * Compare option strings for equality.
+ * If the first two chars of the strings differ, it means that
+ * we are looking at different versions of the options string,
+ * therefore don't compare them and return true.
+ */
+
+bool
+options_cmp_equal(char *actual, const char *expected)
+{
+    return options_cmp_equal_safe(actual, expected, strlen(actual) + 1);
+}
+
+void
+options_warning(char *actual, const char *expected)
+{
+    options_warning_safe(actual, expected, strlen(actual) + 1);
+}
+
+static const char *
+options_warning_extract_parm1(const char *option_string,
+                              struct gc_arena *gc_ret)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer b = string_alloc_buf(option_string, &gc);
+    char *p = gc_malloc(OPTION_PARM_SIZE, false, &gc);
+    const char *ret;
+
+    buf_parse(&b, ' ', p, OPTION_PARM_SIZE);
+    ret = string_alloc(p, gc_ret);
+    gc_free(&gc);
+    return ret;
+}
+
+static void
+options_warning_safe_scan2(const int msglevel,
+                           const int delim,
+                           const bool report_inconsistent,
+                           const char *p1,
+                           const struct buffer *b2_src,
+                           const char *b1_name,
+                           const char *b2_name)
+{
+    /* We will stop sending 'key-method', 'keydir', 'proto' and 'tls-auth' in
+     * OCC in a future version (because it's not useful). To reduce questions
+     * when interoperating, we no longer printing a warning about it.
+     */
+    if (strprefix(p1, "key-method ")
+        || strprefix(p1, "keydir ")
+        || strprefix(p1, "proto ")
+        || strprefix(p1, "tls-auth ")
+        || strprefix(p1, "tun-ipv6"))
+    {
+        return;
+    }
+
+    if (strlen(p1) > 0)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer b2 = *b2_src;
+        const char *p1_prefix = options_warning_extract_parm1(p1, &gc);
+        char *p2 = gc_malloc(OPTION_PARM_SIZE, false, &gc);
+
+        while (buf_parse(&b2, delim, p2, OPTION_PARM_SIZE))
+        {
+            if (strlen(p2))
+            {
+                const char *p2_prefix = options_warning_extract_parm1(p2, &gc);
+
+                if (!strcmp(p1, p2))
+                {
+                    goto done;
+                }
+                if (!strcmp(p1_prefix, p2_prefix))
+                {
+                    if (report_inconsistent)
+                    {
+                        msg(msglevel, "WARNING: '%s' is used inconsistently, %s='%s', %s='%s'",
+                            safe_print(p1_prefix, &gc),
+                            b1_name,
+                            safe_print(p1, &gc),
+                            b2_name,
+                            safe_print(p2, &gc));
+                    }
+                    goto done;
+                }
+            }
+        }
+
+        msg(msglevel, "WARNING: '%s' is present in %s config but missing in %s config, %s='%s'",
+            safe_print(p1_prefix, &gc),
+            b1_name,
+            b2_name,
+            b1_name,
+            safe_print(p1, &gc));
+
+done:
+        gc_free(&gc);
+    }
+}
+
+static void
+options_warning_safe_scan1(const int msglevel,
+                           const int delim,
+                           const bool report_inconsistent,
+                           const struct buffer *b1_src,
+                           const struct buffer *b2_src,
+                           const char *b1_name,
+                           const char *b2_name)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer b = *b1_src;
+    char *p = gc_malloc(OPTION_PARM_SIZE, true, &gc);
+
+    while (buf_parse(&b, delim, p, OPTION_PARM_SIZE))
+    {
+        options_warning_safe_scan2(msglevel, delim, report_inconsistent, p, b2_src, b1_name, b2_name);
+    }
+
+    gc_free(&gc);
+}
+
+static void
+options_warning_safe_ml(const int msglevel, char *actual, const char *expected, size_t actual_n)
+{
+    struct gc_arena gc = gc_new();
+
+    if (actual_n > 0)
+    {
+        struct buffer local = alloc_buf_gc(OPTION_PARM_SIZE + 16, &gc);
+        struct buffer remote = alloc_buf_gc(OPTION_PARM_SIZE + 16, &gc);
+        actual[actual_n - 1] = 0;
+
+        buf_printf(&local, "version %s", expected);
+        buf_printf(&remote, "version %s", actual);
+
+        options_warning_safe_scan1(msglevel, ',', true,
+                                   &local, &remote,
+                                   "local", "remote");
+
+        options_warning_safe_scan1(msglevel, ',', false,
+                                   &remote, &local,
+                                   "remote", "local");
+    }
+
+    gc_free(&gc);
+}
+
+bool
+options_cmp_equal_safe(char *actual, const char *expected, size_t actual_n)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = true;
+
+    if (actual_n > 0)
+    {
+        actual[actual_n - 1] = 0;
+#ifndef ENABLE_STRICT_OPTIONS_CHECK
+        if (strncmp(actual, expected, 2))
+        {
+            msg(D_SHOW_OCC, "NOTE: Options consistency check may be skewed by version differences");
+            options_warning_safe_ml(D_SHOW_OCC, actual, expected, actual_n);
+        }
+        else
+#endif
+        ret = !strcmp(actual, expected);
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+void
+options_warning_safe(char *actual, const char *expected, size_t actual_n)
+{
+    options_warning_safe_ml(M_WARN, actual, expected, actual_n);
+}
+
+const char *
+options_string_version(const char *s, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(4, gc);
+    strncpynt((char *) BPTR(&out), s, 3);
+    return BSTR(&out);
+}
+
+#endif /* ENABLE_OCC */
+
+char *
+options_string_extract_option(const char *options_string,const char *opt_name,
+                              struct gc_arena *gc)
+{
+    char *ret = NULL;
+    const size_t opt_name_len = strlen(opt_name);
+
+    const char *p = options_string;
+    while (p)
+    {
+        if (0 == strncmp(p, opt_name, opt_name_len)
+            && strlen(p) > (opt_name_len+1) && p[opt_name_len] == ' ')
+        {
+            /* option found, extract value */
+            const char *start = &p[opt_name_len+1];
+            const char *end = strchr(p, ',');
+            size_t val_len = end ? end - start : strlen(start);
+            ret = gc_malloc(val_len+1, true, gc);
+            memcpy(ret, start, val_len);
+            break;
+        }
+        p = strchr(p, ',');
+        if (p)
+        {
+            p++; /* skip delimiter */
+        }
+    }
+    return ret;
+}
+
+static void
+foreign_option(struct options *o, char *argv[], int len, struct env_set *es)
+{
+    if (len > 0)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer name = alloc_buf_gc(OPTION_PARM_SIZE, &gc);
+        struct buffer value = alloc_buf_gc(OPTION_PARM_SIZE, &gc);
+        int i;
+        bool first = true;
+        bool good = true;
+
+        good &= buf_printf(&name, "foreign_option_%d", o->foreign_option_index + 1);
+        ++o->foreign_option_index;
+        for (i = 0; i < len; ++i)
+        {
+            if (argv[i])
+            {
+                if (!first)
+                {
+                    good &= buf_printf(&value, " ");
+                }
+                good &= buf_printf(&value, "%s", argv[i]);
+                first = false;
+            }
+        }
+        if (good)
+        {
+            setenv_str(es, BSTR(&name), BSTR(&value));
+        }
+        else
+        {
+            msg(M_WARN, "foreign_option: name/value overflow");
+        }
+        gc_free(&gc);
+    }
+}
+
+/*
+ * parse/print topology coding
+ */
+
+int
+parse_topology(const char *str, const int msglevel)
+{
+    if (streq(str, "net30"))
+    {
+        return TOP_NET30;
+    }
+    else if (streq(str, "p2p"))
+    {
+        return TOP_P2P;
+    }
+    else if (streq(str, "subnet"))
+    {
+        return TOP_SUBNET;
+    }
+    else
+    {
+        msg(msglevel, "--topology must be net30, p2p, or subnet");
+        return TOP_UNDEF;
+    }
+}
+
+const char *
+print_topology(const int topology)
+{
+    switch (topology)
+    {
+        case TOP_UNDEF:
+            return "undef";
+
+        case TOP_NET30:
+            return "net30";
+
+        case TOP_P2P:
+            return "p2p";
+
+        case TOP_SUBNET:
+            return "subnet";
+
+        default:
+            return "unknown";
+    }
+}
+
+#if P2MP
+
+/*
+ * Manage auth-retry variable
+ */
+
+static int global_auth_retry; /* GLOBAL */
+
+int
+auth_retry_get(void)
+{
+    return global_auth_retry;
+}
+
+bool
+auth_retry_set(const int msglevel, const char *option)
+{
+    if (streq(option, "interact"))
+    {
+        global_auth_retry = AR_INTERACT;
+    }
+    else if (streq(option, "nointeract"))
+    {
+        global_auth_retry = AR_NOINTERACT;
+    }
+    else if (streq(option, "none"))
+    {
+        global_auth_retry = AR_NONE;
+    }
+    else
+    {
+        msg(msglevel, "--auth-retry method must be 'interact', 'nointeract', or 'none'");
+        return false;
+    }
+    return true;
+}
+
+const char *
+auth_retry_print(void)
+{
+    switch (global_auth_retry)
+    {
+        case AR_NONE:
+            return "none";
+
+        case AR_NOINTERACT:
+            return "nointeract";
+
+        case AR_INTERACT:
+            return "interact";
+
+        default:
+            return "???";
+    }
+}
+
+#endif /* if P2MP */
+
+/*
+ * Print the help message.
+ */
+static void
+usage(void)
+{
+    FILE *fp = msg_fp(0);
+
+#ifdef ENABLE_SMALL
+
+    fprintf(fp, "Usage message not available\n");
+
+#else
+
+    struct options o;
+    init_options(&o, true);
+
+#ifdef ENABLE_CRYPTO
+    fprintf(fp, usage_message,
+            title_string,
+            o.ce.connect_retry_seconds,
+            o.ce.connect_retry_seconds_max,
+            o.ce.local_port, o.ce.remote_port,
+            TUN_MTU_DEFAULT, TAP_MTU_EXTRA_DEFAULT,
+            o.verbosity,
+            o.authname, o.ciphername,
+            o.replay_window, o.replay_time,
+            o.tls_timeout, o.renegotiate_seconds,
+            o.handshake_window, o.transition_window);
+#else  /* ifdef ENABLE_CRYPTO */
+    fprintf(fp, usage_message,
+            title_string,
+            o.ce.connect_retry_seconds,
+            o.ce.connect_retry_seconds_max,
+            o.ce.local_port, o.ce.remote_port,
+            TUN_MTU_DEFAULT, TAP_MTU_EXTRA_DEFAULT,
+            o.verbosity);
+#endif
+    fflush(fp);
+
+#endif /* ENABLE_SMALL */
+
+    openvpn_exit(OPENVPN_EXIT_STATUS_USAGE); /* exit point */
+}
+
+void
+usage_small(void)
+{
+    msg(M_WARN|M_NOPREFIX, "Use --help for more information.");
+    openvpn_exit(OPENVPN_EXIT_STATUS_USAGE); /* exit point */
+}
+
+#ifdef _WIN32
+void
+show_windows_version(const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    msg(flags, "Windows version %s", win32_version_string(&gc, true));
+    gc_free(&gc);
+}
+#endif
+
+void
+show_library_versions(const unsigned int flags)
+{
+#ifdef ENABLE_CRYPTO
+#define SSL_LIB_VER_STR get_ssl_library_version()
+#else
+#define SSL_LIB_VER_STR ""
+#endif
+#ifdef ENABLE_LZO
+#define LZO_LIB_VER_STR ", LZO ", lzo_version_string()
+#else
+#define LZO_LIB_VER_STR "", ""
+#endif
+
+    msg(flags, "library versions: %s%s%s", SSL_LIB_VER_STR, LZO_LIB_VER_STR);
+
+#undef SSL_LIB_VER_STR
+#undef LZO_LIB_VER_STR
+}
+
+static void
+usage_version(void)
+{
+    msg(M_INFO|M_NOPREFIX, "%s", title_string);
+    show_library_versions( M_INFO|M_NOPREFIX );
+#ifdef _WIN32
+    show_windows_version( M_INFO|M_NOPREFIX );
+#endif
+    msg(M_INFO|M_NOPREFIX, "Originally developed by James Yonan");
+    msg(M_INFO|M_NOPREFIX, "Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>");
+#ifndef ENABLE_SMALL
+#ifdef CONFIGURE_DEFINES
+    msg(M_INFO|M_NOPREFIX, "Compile time defines: %s", CONFIGURE_DEFINES);
+#endif
+#ifdef CONFIGURE_SPECIAL_BUILD
+    msg(M_INFO|M_NOPREFIX, "special build: %s", CONFIGURE_SPECIAL_BUILD);
+#endif
+#endif
+    openvpn_exit(OPENVPN_EXIT_STATUS_USAGE); /* exit point */
+}
+
+void
+notnull(const char *arg, const char *description)
+{
+    if (!arg)
+    {
+        msg(M_USAGE, "You must define %s", description);
+    }
+}
+
+bool
+string_defined_equal(const char *s1, const char *s2)
+{
+    if (s1 && s2)
+    {
+        return !strcmp(s1, s2);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+#if 0
+static void
+ping_rec_err(int msglevel)
+{
+    msg(msglevel, "only one of --ping-exit or --ping-restart options may be specified");
+}
+#endif
+
+static int
+positive_atoi(const char *str)
+{
+    const int i = atoi(str);
+    return i < 0 ? 0 : i;
+}
+
+#ifdef _WIN32  /* This function is only used when compiling on Windows */
+static unsigned int
+atou(const char *str)
+{
+    unsigned int val = 0;
+    sscanf(str, "%u", &val);
+    return val;
+}
+#endif
+
+static inline bool
+space(unsigned char c)
+{
+    return c == '\0' || isspace(c);
+}
+
+int
+parse_line(const char *line,
+           char *p[],
+           const int n,
+           const char *file,
+           const int line_num,
+           int msglevel,
+           struct gc_arena *gc)
+{
+    const int STATE_INITIAL = 0;
+    const int STATE_READING_QUOTED_PARM = 1;
+    const int STATE_READING_UNQUOTED_PARM = 2;
+    const int STATE_DONE = 3;
+    const int STATE_READING_SQUOTED_PARM = 4;
+
+    const char *error_prefix = "";
+
+    int ret = 0;
+    const char *c = line;
+    int state = STATE_INITIAL;
+    bool backslash = false;
+    char in, out;
+
+#ifdef ENABLE_PKCS11
+#   define PARM_SIZE USER_PASS_LEN
+#else
+#   define PARM_SIZE OPTION_PARM_SIZE
+#endif
+    char parm[PARM_SIZE];
+    unsigned int parm_len = 0;
+
+    msglevel &= ~M_OPTERR;
+
+    if (msglevel & M_MSG_VIRT_OUT)
+    {
+        error_prefix = "ERROR: ";
+    }
+
+    do
+    {
+        in = *c;
+        out = 0;
+
+        if (!backslash && in == '\\' && state != STATE_READING_SQUOTED_PARM)
+        {
+            backslash = true;
+        }
+        else
+        {
+            if (state == STATE_INITIAL)
+            {
+                if (!space(in))
+                {
+                    if (in == ';' || in == '#') /* comment */
+                    {
+                        break;
+                    }
+                    if (!backslash && in == '\"')
+                    {
+                        state = STATE_READING_QUOTED_PARM;
+                    }
+                    else if (!backslash && in == '\'')
+                    {
+                        state = STATE_READING_SQUOTED_PARM;
+                    }
+                    else
+                    {
+                        out = in;
+                        state = STATE_READING_UNQUOTED_PARM;
+                    }
+                }
+            }
+            else if (state == STATE_READING_UNQUOTED_PARM)
+            {
+                if (!backslash && space(in))
+                {
+                    state = STATE_DONE;
+                }
+                else
+                {
+                    out = in;
+                }
+            }
+            else if (state == STATE_READING_QUOTED_PARM)
+            {
+                if (!backslash && in == '\"')
+                {
+                    state = STATE_DONE;
+                }
+                else
+                {
+                    out = in;
+                }
+            }
+            else if (state == STATE_READING_SQUOTED_PARM)
+            {
+                if (in == '\'')
+                {
+                    state = STATE_DONE;
+                }
+                else
+                {
+                    out = in;
+                }
+            }
+            if (state == STATE_DONE)
+            {
+                /* ASSERT (parm_len > 0); */
+                p[ret] = gc_malloc(parm_len + 1, true, gc);
+                memcpy(p[ret], parm, parm_len);
+                p[ret][parm_len] = '\0';
+                state = STATE_INITIAL;
+                parm_len = 0;
+                ++ret;
+            }
+
+            if (backslash && out)
+            {
+                if (!(out == '\\' || out == '\"' || space(out)))
+                {
+#ifdef ENABLE_SMALL
+                    msg(msglevel, "%sOptions warning: Bad backslash ('\\') usage in %s:%d", error_prefix, file, line_num);
+#else
+                    msg(msglevel, "%sOptions warning: Bad backslash ('\\') usage in %s:%d: remember that backslashes are treated as shell-escapes and if you need to pass backslash characters as part of a Windows filename, you should use double backslashes such as \"c:\\\\" PACKAGE "\\\\static.key\"", error_prefix, file, line_num);
+#endif
+                    return 0;
+                }
+            }
+            backslash = false;
+        }
+
+        /* store parameter character */
+        if (out)
+        {
+            if (parm_len >= SIZE(parm))
+            {
+                parm[SIZE(parm) - 1] = 0;
+                msg(msglevel, "%sOptions error: Parameter at %s:%d is too long (%d chars max): %s",
+                    error_prefix, file, line_num, (int) SIZE(parm), parm);
+                return 0;
+            }
+            parm[parm_len++] = out;
+        }
+
+        /* avoid overflow if too many parms in one config file line */
+        if (ret >= n)
+        {
+            break;
+        }
+
+    } while (*c++ != '\0');
+
+    if (state == STATE_READING_QUOTED_PARM)
+    {
+        msg(msglevel, "%sOptions error: No closing quotation (\") in %s:%d", error_prefix, file, line_num);
+        return 0;
+    }
+    if (state == STATE_READING_SQUOTED_PARM)
+    {
+        msg(msglevel, "%sOptions error: No closing single quotation (\') in %s:%d", error_prefix, file, line_num);
+        return 0;
+    }
+    if (state != STATE_INITIAL)
+    {
+        msg(msglevel, "%sOptions error: Residual parse state (%d) in %s:%d", error_prefix, state, file, line_num);
+        return 0;
+    }
+#if 0
+    {
+        int i;
+        for (i = 0; i < ret; ++i)
+        {
+            msg(M_INFO|M_NOPREFIX, "%s:%d ARG[%d] '%s'", file, line_num, i, p[i]);
+        }
+    }
+#endif
+    return ret;
+}
+
+static void
+bypass_doubledash(char **p)
+{
+    if (strlen(*p) >= 3 && !strncmp(*p, "--", 2))
+    {
+        *p += 2;
+    }
+}
+
+struct in_src {
+#define IS_TYPE_FP 1
+#define IS_TYPE_BUF 2
+    int type;
+    union {
+        FILE *fp;
+        struct buffer *multiline;
+    } u;
+};
+
+static bool
+in_src_get(const struct in_src *is, char *line, const int size)
+{
+    if (is->type == IS_TYPE_FP)
+    {
+        return BOOL_CAST(fgets(line, size, is->u.fp));
+    }
+    else if (is->type == IS_TYPE_BUF)
+    {
+        bool status = buf_parse(is->u.multiline, '\n', line, size);
+        if ((int) strlen(line) + 1 < size)
+        {
+            strcat(line, "\n");
+        }
+        return status;
+    }
+    else
+    {
+        ASSERT(0);
+        return false;
+    }
+}
+
+static char *
+read_inline_file(struct in_src *is, const char *close_tag, struct gc_arena *gc)
+{
+    char line[OPTION_LINE_SIZE];
+    struct buffer buf = alloc_buf(8*OPTION_LINE_SIZE);
+    char *ret;
+    bool endtagfound = false;
+
+    while (in_src_get(is, line, sizeof(line)))
+    {
+        char *line_ptr = line;
+        /* Remove leading spaces */
+        while (isspace(*line_ptr))
+        {
+            line_ptr++;
+        }
+        if (!strncmp(line_ptr, close_tag, strlen(close_tag)))
+        {
+            endtagfound = true;
+            break;
+        }
+        if (!buf_safe(&buf, strlen(line)+1))
+        {
+            /* Increase buffer size */
+            struct buffer buf2 = alloc_buf(buf.capacity * 2);
+            ASSERT(buf_copy(&buf2, &buf));
+            buf_clear(&buf);
+            free_buf(&buf);
+            buf = buf2;
+        }
+        buf_printf(&buf, "%s", line);
+    }
+    if (!endtagfound)
+    {
+        msg(M_FATAL, "ERROR: Endtag %s missing", close_tag);
+    }
+    ret = string_alloc(BSTR(&buf), gc);
+    buf_clear(&buf);
+    free_buf(&buf);
+    secure_memzero(line, sizeof(line));
+    return ret;
+}
+
+static bool
+check_inline_file(struct in_src *is, char *p[], struct gc_arena *gc)
+{
+    bool ret = false;
+    if (p[0] && !p[1])
+    {
+        char *arg = p[0];
+        if (arg[0] == '<' && arg[strlen(arg)-1] == '>')
+        {
+            struct buffer close_tag;
+            arg[strlen(arg)-1] = '\0';
+            p[0] = string_alloc(arg+1, gc);
+            p[1] = string_alloc(INLINE_FILE_TAG, gc);
+            close_tag = alloc_buf(strlen(p[0]) + 4);
+            buf_printf(&close_tag, "</%s>", p[0]);
+            p[2] = read_inline_file(is, BSTR(&close_tag), gc);
+            p[3] = NULL;
+            free_buf(&close_tag);
+            ret = true;
+        }
+    }
+    return ret;
+}
+
+static bool
+check_inline_file_via_fp(FILE *fp, char *p[], struct gc_arena *gc)
+{
+    struct in_src is;
+    is.type = IS_TYPE_FP;
+    is.u.fp = fp;
+    return check_inline_file(&is, p, gc);
+}
+
+static bool
+check_inline_file_via_buf(struct buffer *multiline, char *p[], struct gc_arena *gc)
+{
+    struct in_src is;
+    is.type = IS_TYPE_BUF;
+    is.u.multiline = multiline;
+    return check_inline_file(&is, p, gc);
+}
+
+static void
+add_option(struct options *options,
+           char *p[],
+           const char *file,
+           int line,
+           const int level,
+           const int msglevel,
+           const unsigned int permission_mask,
+           unsigned int *option_types_found,
+           struct env_set *es);
+
+static void
+read_config_file(struct options *options,
+                 const char *file,
+                 int level,
+                 const char *top_file,
+                 const int top_line,
+                 const int msglevel,
+                 const unsigned int permission_mask,
+                 unsigned int *option_types_found,
+                 struct env_set *es)
+{
+    const int max_recursive_levels = 10;
+    FILE *fp;
+    int line_num;
+    char line[OPTION_LINE_SIZE+1];
+    char *p[MAX_PARMS+1];
+
+    ++level;
+    if (level <= max_recursive_levels)
+    {
+        if (streq(file, "stdin"))
+        {
+            fp = stdin;
+        }
+        else
+        {
+            fp = platform_fopen(file, "r");
+        }
+        if (fp)
+        {
+            line_num = 0;
+            while (fgets(line, sizeof(line), fp))
+            {
+                int offset = 0;
+                CLEAR(p);
+                ++line_num;
+                if (strlen(line) == OPTION_LINE_SIZE)
+                {
+                    msg(msglevel, "In %s:%d: Maximum option line length (%d) exceeded, line starts with %s",
+                        file, line_num, OPTION_LINE_SIZE, line);
+                }
+
+                /* Ignore UTF-8 BOM at start of stream */
+                if (line_num == 1 && strncmp(line, "\xEF\xBB\xBF", 3) == 0)
+                {
+                    offset = 3;
+                }
+                if (parse_line(line + offset, p, SIZE(p)-1, file, line_num, msglevel, &options->gc))
+                {
+                    bypass_doubledash(&p[0]);
+                    check_inline_file_via_fp(fp, p, &options->gc);
+                    add_option(options, p, file, line_num, level, msglevel, permission_mask, option_types_found, es);
+                }
+            }
+            if (fp != stdin)
+            {
+                fclose(fp);
+            }
+        }
+        else
+        {
+            msg(msglevel, "In %s:%d: Error opening configuration file: %s", top_file, top_line, file);
+        }
+    }
+    else
+    {
+        msg(msglevel, "In %s:%d: Maximum recursive include levels exceeded in include attempt of file %s -- probably you have a configuration file that tries to include itself.", top_file, top_line, file);
+    }
+    secure_memzero(line, sizeof(line));
+    CLEAR(p);
+}
+
+static void
+read_config_string(const char *prefix,
+                   struct options *options,
+                   const char *config,
+                   const int msglevel,
+                   const unsigned int permission_mask,
+                   unsigned int *option_types_found,
+                   struct env_set *es)
+{
+    char line[OPTION_LINE_SIZE];
+    struct buffer multiline;
+    int line_num = 0;
+
+    buf_set_read(&multiline, (uint8_t *)config, strlen(config));
+
+    while (buf_parse(&multiline, '\n', line, sizeof(line)))
+    {
+        char *p[MAX_PARMS+1];
+        CLEAR(p);
+        ++line_num;
+        if (parse_line(line, p, SIZE(p)-1, prefix, line_num, msglevel, &options->gc))
+        {
+            bypass_doubledash(&p[0]);
+            check_inline_file_via_buf(&multiline, p, &options->gc);
+            add_option(options, p, prefix, line_num, 0, msglevel, permission_mask, option_types_found, es);
+        }
+        CLEAR(p);
+    }
+    secure_memzero(line, sizeof(line));
+}
+
+void
+parse_argv(struct options *options,
+           const int argc,
+           char *argv[],
+           const int msglevel,
+           const unsigned int permission_mask,
+           unsigned int *option_types_found,
+           struct env_set *es)
+{
+    int i, j;
+
+    /* usage message */
+    if (argc <= 1)
+    {
+        usage();
+    }
+
+    /* config filename specified only? */
+    if (argc == 2 && strncmp(argv[1], "--", 2))
+    {
+        char *p[MAX_PARMS];
+        CLEAR(p);
+        p[0] = "config";
+        p[1] = argv[1];
+        add_option(options, p, NULL, 0, 0, msglevel, permission_mask, option_types_found, es);
+    }
+    else
+    {
+        /* parse command line */
+        for (i = 1; i < argc; ++i)
+        {
+            char *p[MAX_PARMS];
+            CLEAR(p);
+            p[0] = argv[i];
+            if (strncmp(p[0], "--", 2))
+            {
+                msg(msglevel, "I'm trying to parse \"%s\" as an --option parameter but I don't see a leading '--'", p[0]);
+            }
+            else
+            {
+                p[0] += 2;
+            }
+
+            for (j = 1; j < MAX_PARMS; ++j)
+            {
+                if (i + j < argc)
+                {
+                    char *arg = argv[i + j];
+                    if (strncmp(arg, "--", 2))
+                    {
+                        p[j] = arg;
+                    }
+                    else
+                    {
+                        break;
+                    }
+                }
+            }
+            add_option(options, p, NULL, 0, 0, msglevel, permission_mask, option_types_found, es);
+            i += j - 1;
+        }
+    }
+}
+
+/**
+ * Filter an option line by all pull filters.
+ *
+ * If a match is found, the line is modified depending on
+ * the filter type, and returns true. If the filter type is
+ * reject, SIGUSR1 is triggered and the return value is false.
+ * In that case the caller must end the push processing.
+ */
+static bool
+apply_pull_filter(const struct options *o, char *line)
+{
+    struct pull_filter *f;
+
+    if (!o->pull_filter_list)
+    {
+        return true;
+    }
+
+    for (f = o->pull_filter_list->head; f; f = f->next)
+    {
+        if (f->type == PUF_TYPE_ACCEPT && strncmp(line, f->pattern, f->size) == 0)
+        {
+            msg(D_LOW, "Pushed option accepted by filter: '%s'", line);
+            return true;
+        }
+        else if (f->type == PUF_TYPE_IGNORE && strncmp(line, f->pattern, f->size) == 0)
+        {
+            msg(D_PUSH, "Pushed option removed by filter: '%s'", line);
+            *line = '\0';
+            return true;
+        }
+        else if (f->type == PUF_TYPE_REJECT && strncmp(line, f->pattern, f->size) == 0)
+        {
+            msg(M_WARN, "Pushed option rejected by filter: '%s'. Restarting.", line);
+            *line = '\0';
+            throw_signal_soft(SIGUSR1, "Offending option received from server");
+            return false;
+        }
+    }
+    return true;
+}
+
+bool
+apply_push_options(struct options *options,
+                   struct buffer *buf,
+                   unsigned int permission_mask,
+                   unsigned int *option_types_found,
+                   struct env_set *es)
+{
+    char line[OPTION_PARM_SIZE];
+    int line_num = 0;
+    const char *file = "[PUSH-OPTIONS]";
+    const int msglevel = D_PUSH_ERRORS|M_OPTERR;
+
+    while (buf_parse(buf, ',', line, sizeof(line)))
+    {
+        char *p[MAX_PARMS+1];
+        CLEAR(p);
+        ++line_num;
+        if (!apply_pull_filter(options, line))
+        {
+            return false; /* Cause push/pull error and stop push processing */
+        }
+        if (parse_line(line, p, SIZE(p)-1, file, line_num, msglevel, &options->gc))
+        {
+            add_option(options, p, file, line_num, 0, msglevel, permission_mask, option_types_found, es);
+        }
+    }
+    return true;
+}
+
+void
+options_server_import(struct options *o,
+                      const char *filename,
+                      int msglevel,
+                      unsigned int permission_mask,
+                      unsigned int *option_types_found,
+                      struct env_set *es)
+{
+    msg(D_PUSH, "OPTIONS IMPORT: reading client specific options from: %s", filename);
+    read_config_file(o,
+                     filename,
+                     0,
+                     filename,
+                     0,
+                     msglevel,
+                     permission_mask,
+                     option_types_found,
+                     es);
+}
+
+void
+options_string_import(struct options *options,
+                      const char *config,
+                      const int msglevel,
+                      const unsigned int permission_mask,
+                      unsigned int *option_types_found,
+                      struct env_set *es)
+{
+    read_config_string("[CONFIG-STRING]", options, config, msglevel, permission_mask, option_types_found, es);
+}
+
+#if P2MP
+
+#define VERIFY_PERMISSION(mask) { if (!verify_permission(p[0], file, line, (mask), permission_mask, option_types_found, msglevel, options)) {goto err;}}
+
+static bool
+verify_permission(const char *name,
+                  const char *file,
+                  int line,
+                  const unsigned int type,
+                  const unsigned int allowed,
+                  unsigned int *found,
+                  const int msglevel,
+                  struct options *options)
+{
+    if (!(type & allowed))
+    {
+        msg(msglevel, "option '%s' cannot be used in this context (%s)", name, file);
+        return false;
+    }
+
+    if (found)
+    {
+        *found |= type;
+    }
+
+#ifndef ENABLE_SMALL
+    /* Check if this options is allowed in connection block,
+     * but we are currently not in a connection block
+     * unless this is a pushed option.
+     * Parsing a connection block uses a temporary options struct without
+     * connection_list
+     */
+
+    if ((type & OPT_P_CONNECTION) && options->connection_list
+        && !(allowed & OPT_P_PULL_MODE))
+    {
+        if (file)
+        {
+            msg(M_WARN, "Option '%s' in %s:%d is ignored by previous <connection> blocks ", name, file, line);
+        }
+        else
+        {
+            msg(M_WARN, "Option '%s' is ignored by previous <connection> blocks", name);
+        }
+    }
+#endif
+    return true;
+}
+
+#else  /* if P2MP */
+
+#define VERIFY_PERMISSION(mask)
+
+#endif /* if P2MP */
+
+/*
+ * Check that an option doesn't have too
+ * many parameters.
+ */
+
+#define NM_QUOTE_HINT (1<<0)
+
+static bool
+no_more_than_n_args(const int msglevel,
+                    char *p[],
+                    const int max,
+                    const unsigned int flags)
+{
+    const int len = string_array_len((const char **)p);
+
+    if (!len)
+    {
+        return false;
+    }
+
+    if (len > max)
+    {
+        msg(msglevel, "the --%s directive should have at most %d parameter%s.%s",
+            p[0],
+            max - 1,
+            max >= 3 ? "s" : "",
+            (flags & NM_QUOTE_HINT) ? "  To pass a list of arguments as one of the parameters, try enclosing them in double quotes (\"\")." : "");
+        return false;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+static inline int
+msglevel_forward_compatible(struct options *options, const int msglevel)
+{
+    return options->forward_compatible ? M_WARN : msglevel;
+}
+
+static void
+set_user_script(struct options *options,
+                const char **script,
+                const char *new_script,
+                const char *type,
+                bool in_chroot)
+{
+    if (*script)
+    {
+        msg(M_WARN, "Multiple --%s scripts defined.  "
+            "The previously configured script is overridden.", type);
+    }
+    *script = new_script;
+    options->user_script_used = true;
+
+#ifndef ENABLE_SMALL
+    {
+        char script_name[100];
+        openvpn_snprintf(script_name, sizeof(script_name),
+                         "--%s script", type);
+
+        if (check_cmd_access(*script, script_name, (in_chroot ? options->chroot_dir : NULL)))
+        {
+            msg(M_USAGE, "Please correct this error.");
+        }
+
+    }
+#endif
+}
+
+
+static void
+add_option(struct options *options,
+           char *p[],
+           const char *file,
+           int line,
+           const int level,
+           const int msglevel,
+           const unsigned int permission_mask,
+           unsigned int *option_types_found,
+           struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    const bool pull_mode = BOOL_CAST(permission_mask & OPT_P_PULL_MODE);
+    int msglevel_fc = msglevel_forward_compatible(options, msglevel);
+
+    ASSERT(MAX_PARMS >= 7);
+
+    /*
+     * If directive begins with "setenv opt" prefix, don't raise an error if
+     * directive is unrecognized.
+     */
+    if (streq(p[0], "setenv") && p[1] && streq(p[1], "opt") && !(permission_mask & OPT_P_PULL_MODE))
+    {
+        if (!p[2])
+        {
+            p[2] = "setenv opt"; /* will trigger an error that includes setenv opt */
+        }
+        p += 2;
+        msglevel_fc = M_WARN;
+    }
+
+    if (!file)
+    {
+        file = "[CMD-LINE]";
+        line = 1;
+    }
+    if (streq(p[0], "help"))
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        usage();
+        if (p[1])
+        {
+            msg(msglevel, "--help does not accept any parameters");
+            goto err;
+        }
+    }
+    if (streq(p[0], "version") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        usage_version();
+    }
+    else if (streq(p[0], "config") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_CONFIG);
+
+        /* save first config file only in options */
+        if (!options->config)
+        {
+            options->config = p[1];
+        }
+
+        read_config_file(options, p[1], level, file, line, msglevel, permission_mask, option_types_found, es);
+    }
+#if defined(ENABLE_DEBUG) && !defined(ENABLE_SMALL)
+    else if (streq(p[0], "show-gateway") && !p[2])
+    {
+        struct route_gateway_info rgi;
+        struct route_ipv6_gateway_info rgi6;
+        struct in6_addr remote = IN6ADDR_ANY_INIT;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[1])
+        {
+            get_ipv6_addr(p[1], &remote, NULL, M_WARN);
+        }
+        get_default_gateway(&rgi);
+        get_default_gateway_ipv6(&rgi6, &remote);
+        print_default_gateway(M_INFO, &rgi, &rgi6);
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+#endif
+#if 0
+    else if (streq(p[0], "foreign-option") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        foreign_option(options, p, 3, es);
+    }
+#endif
+    else if (streq(p[0], "echo") || streq(p[0], "parameter"))
+    {
+        struct buffer string = alloc_buf_gc(OPTION_PARM_SIZE, &gc);
+        int j;
+        bool good = true;
+
+        VERIFY_PERMISSION(OPT_P_ECHO);
+
+        for (j = 1; j < MAX_PARMS; ++j)
+        {
+            if (!p[j])
+            {
+                break;
+            }
+            if (j > 1)
+            {
+                good &= buf_printf(&string, " ");
+            }
+            good &= buf_printf(&string, "%s", p[j]);
+        }
+        if (good)
+        {
+#if 0
+            /* removed for now since ECHO can potentially include
+             * security-sensitive strings */
+            msg(M_INFO, "%s:%s",
+                pull_mode ? "ECHO-PULL" : "ECHO",
+                BSTR(&string));
+#endif
+#ifdef ENABLE_MANAGEMENT
+            if (management)
+            {
+                management_echo(management, BSTR(&string), pull_mode);
+            }
+#endif
+        }
+        else
+        {
+            msg(M_WARN, "echo/parameter option overflow");
+        }
+    }
+#ifdef ENABLE_MANAGEMENT
+    else if (streq(p[0], "management") && p[1] && p[2] && !p[4])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[2], "unix"))
+        {
+#if UNIX_SOCK_SUPPORT
+            options->management_flags |= MF_UNIX_SOCK;
+#else
+            msg(msglevel, "MANAGEMENT: this platform does not support unix domain sockets");
+            goto err;
+#endif
+        }
+
+        options->management_addr = p[1];
+        options->management_port = p[2];
+        if (p[3])
+        {
+            options->management_user_pass = p[3];
+        }
+    }
+    else if (streq(p[0], "management-client-user") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_client_user = p[1];
+    }
+    else if (streq(p[0], "management-client-group") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_client_group = p[1];
+    }
+    else if (streq(p[0], "management-query-passwords") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_QUERY_PASSWORDS;
+    }
+    else if (streq(p[0], "management-query-remote") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_QUERY_REMOTE;
+    }
+    else if (streq(p[0], "management-query-proxy") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_QUERY_PROXY;
+    }
+    else if (streq(p[0], "management-hold") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_HOLD;
+    }
+    else if (streq(p[0], "management-signal") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_SIGNAL;
+    }
+    else if (streq(p[0], "management-forget-disconnect") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_FORGET_DISCONNECT;
+    }
+    else if (streq(p[0], "management-up-down") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_UP_DOWN;
+    }
+    else if (streq(p[0], "management-client") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_CONNECT_AS_CLIENT;
+        options->management_write_peer_info_file = p[1];
+    }
+#ifdef MANAGMENT_EXTERNAL_KEY
+    else if (streq(p[0], "management-external-key") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_EXTERNAL_KEY;
+    }
+    else if (streq(p[0], "management-external-cert") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_EXTERNAL_CERT;
+        options->management_certificate = p[1];
+    }
+#endif
+#ifdef MANAGEMENT_DEF_AUTH
+    else if (streq(p[0], "management-client-auth") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= MF_CLIENT_AUTH;
+    }
+#endif
+#ifdef MANAGEMENT_PF
+    else if (streq(p[0], "management-client-pf") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->management_flags |= (MF_CLIENT_PF | MF_CLIENT_AUTH);
+    }
+#endif
+    else if (streq(p[0], "management-log-cache") && p[1] && !p[2])
+    {
+        int cache;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        cache = atoi(p[1]);
+        if (cache < 1)
+        {
+            msg(msglevel, "--management-log-cache parameter is out of range");
+            goto err;
+        }
+        options->management_log_history_cache = cache;
+    }
+#endif /* ifdef ENABLE_MANAGEMENT */
+#ifdef ENABLE_PLUGIN
+    else if (streq(p[0], "plugin") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_PLUGIN);
+        if (!options->plugin_list)
+        {
+            options->plugin_list = plugin_option_list_new(&options->gc);
+        }
+        if (!plugin_option_list_add(options->plugin_list, &p[1], &options->gc))
+        {
+            msg(msglevel, "plugin add failed: %s", p[1]);
+            goto err;
+        }
+    }
+#endif
+    else if (streq(p[0], "mode") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "p2p"))
+        {
+            options->mode = MODE_POINT_TO_POINT;
+        }
+#if P2MP_SERVER
+        else if (streq(p[1], "server"))
+        {
+            options->mode = MODE_SERVER;
+        }
+#endif
+        else
+        {
+            msg(msglevel, "Bad --mode parameter: %s", p[1]);
+            goto err;
+        }
+    }
+    else if (streq(p[0], "dev") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->dev = p[1];
+    }
+    else if (streq(p[0], "dev-type") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->dev_type = p[1];
+    }
+    else if (streq(p[0], "dev-node") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->dev_node = p[1];
+    }
+    else if (streq(p[0], "lladdr") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        if (mac_addr_safe(p[1])) /* MAC address only */
+        {
+            options->lladdr = p[1];
+        }
+        else
+        {
+            msg(msglevel, "lladdr parm '%s' must be a MAC address", p[1]);
+            goto err;
+        }
+    }
+    else if (streq(p[0], "topology") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        options->topology = parse_topology(p[1], msglevel);
+    }
+    else if (streq(p[0], "tun-ipv6") && !p[1])
+    {
+        if (!pull_mode)
+        {
+            msg(M_WARN, "Note: option tun-ipv6 is ignored because modern operating systems do not need special IPv6 tun handling anymore.");
+        }
+    }
+#ifdef ENABLE_IPROUTE
+    else if (streq(p[0], "iproute") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        iproute_path = p[1];
+    }
+#endif
+    else if (streq(p[0], "ifconfig") && p[1] && p[2] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        if (ip_or_dns_addr_safe(p[1], options->allow_pull_fqdn) && ip_or_dns_addr_safe(p[2], options->allow_pull_fqdn)) /* FQDN -- may be DNS name */
+        {
+            options->ifconfig_local = p[1];
+            options->ifconfig_remote_netmask = p[2];
+        }
+        else
+        {
+            msg(msglevel, "ifconfig parms '%s' and '%s' must be valid addresses", p[1], p[2]);
+            goto err;
+        }
+    }
+    else if (streq(p[0], "ifconfig-ipv6") && p[1] && p[2] && !p[3])
+    {
+        unsigned int netbits;
+
+        VERIFY_PERMISSION(OPT_P_UP);
+        if (get_ipv6_addr( p[1], NULL, &netbits, msglevel )
+            && ipv6_addr_safe( p[2] ) )
+        {
+            if (netbits < 64 || netbits > 124)
+            {
+                msg( msglevel, "ifconfig-ipv6: /netbits must be between 64 and 124, not '/%d'", netbits );
+                goto err;
+            }
+
+            options->ifconfig_ipv6_local = get_ipv6_addr_no_netbits(p[1], &options->gc);
+            options->ifconfig_ipv6_netbits = netbits;
+            options->ifconfig_ipv6_remote = p[2];
+        }
+        else
+        {
+            msg(msglevel, "ifconfig-ipv6 parms '%s' and '%s' must be valid addresses", p[1], p[2]);
+            goto err;
+        }
+    }
+    else if (streq(p[0], "ifconfig-noexec") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        options->ifconfig_noexec = true;
+    }
+    else if (streq(p[0], "ifconfig-nowarn") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        options->ifconfig_nowarn = true;
+    }
+    else if (streq(p[0], "local") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.local = p[1];
+    }
+    else if (streq(p[0], "remote-random") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->remote_random = true;
+    }
+    else if (streq(p[0], "connection") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            struct options sub;
+            struct connection_entry *e;
+
+            init_options(&sub, true);
+            sub.ce = options->ce;
+            read_config_string("[CONNECTION-OPTIONS]", &sub, p[2], msglevel, OPT_P_CONNECTION, option_types_found, es);
+            if (!sub.ce.remote)
+            {
+                msg(msglevel, "Each 'connection' block must contain exactly one 'remote' directive");
+                uninit_options(&sub);
+                goto err;
+            }
+
+            e = alloc_connection_entry(options, msglevel);
+            if (!e)
+            {
+                uninit_options(&sub);
+                goto err;
+            }
+            *e = sub.ce;
+            gc_transfer(&options->gc, &sub.gc);
+            uninit_options(&sub);
+        }
+    }
+    else if (streq(p[0], "ignore-unknown-option") && p[1])
+    {
+        int i;
+        int j;
+        int numignored = 0;
+        const char **ignore;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        /* Find out how many options to be ignored */
+        for (i = 1; p[i]; i++)
+        {
+            numignored++;
+        }
+
+        /* add number of options already ignored */
+        for (i = 0; options->ignore_unknown_option
+             && options->ignore_unknown_option[i]; i++)
+        {
+            numignored++;
+        }
+
+        /* Allocate array */
+        ALLOC_ARRAY_GC(ignore, const char *, numignored+1, &options->gc);
+        for (i = 0; options->ignore_unknown_option
+             && options->ignore_unknown_option[i]; i++)
+        {
+            ignore[i] = options->ignore_unknown_option[i];
+        }
+
+        options->ignore_unknown_option = ignore;
+
+        for (j = 1; p[j]; j++)
+        {
+            /* Allow the user to specify ignore-unknown-option --opt too */
+            if (p[j][0]=='-' && p[j][1]=='-')
+            {
+                options->ignore_unknown_option[i] = (p[j]+2);
+            }
+            else
+            {
+                options->ignore_unknown_option[i] = p[j];
+            }
+            i++;
+        }
+
+        options->ignore_unknown_option[i] = NULL;
+    }
+#if ENABLE_MANAGEMENT
+    else if (streq(p[0], "http-proxy-override") && p[1] && p[2] && !p[4])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->http_proxy_override = parse_http_proxy_override(p[1], p[2], p[3], msglevel, &options->gc);
+        if (!options->http_proxy_override)
+        {
+            goto err;
+        }
+    }
+#endif
+    else if (streq(p[0], "remote") && p[1] && !p[4])
+    {
+        struct remote_entry re;
+        re.remote = re.remote_port = NULL;
+        re.proto = -1;
+        re.af = 0;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        re.remote = p[1];
+        if (p[2])
+        {
+            re.remote_port = p[2];
+            if (p[3])
+            {
+                const int proto = ascii2proto(p[3]);
+                const sa_family_t af = ascii2af(p[3]);
+                if (proto < 0)
+                {
+                    msg(msglevel, "remote: bad protocol associated with host %s: '%s'", p[1], p[3]);
+                    goto err;
+                }
+                re.proto = proto;
+                re.af = af;
+            }
+        }
+        if (permission_mask & OPT_P_GENERAL)
+        {
+            struct remote_entry *e = alloc_remote_entry(options, msglevel);
+            if (!e)
+            {
+                goto err;
+            }
+            *e = re;
+        }
+        else if (permission_mask & OPT_P_CONNECTION)
+        {
+            connection_entry_load_re(&options->ce, &re);
+        }
+    }
+    else if (streq(p[0], "resolv-retry") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "infinite"))
+        {
+            options->resolve_retry_seconds = RESOLV_RETRY_INFINITE;
+        }
+        else
+        {
+            options->resolve_retry_seconds = positive_atoi(p[1]);
+        }
+    }
+    else if ((streq(p[0], "preresolve") || streq(p[0], "ip-remote-hint")) && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->resolve_in_advance = true;
+        /* Note the ip-remote-hint and the argument p[1] are for
+         * backward compatibility */
+        if (p[1])
+        {
+            options->ip_remote_hint = p[1];
+        }
+    }
+    else if (streq(p[0], "connect-retry") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.connect_retry_seconds = positive_atoi(p[1]);
+        /*
+         * Limit the base value of retry wait interval to 16 bits to avoid
+         * overflow when scaled up for exponential backoff
+         */
+        if (options->ce.connect_retry_seconds > 0xFFFF)
+        {
+            options->ce.connect_retry_seconds = 0xFFFF;
+            msg(M_WARN, "connect retry wait interval truncated to %d",
+                options->ce.connect_retry_seconds);
+        }
+
+        if (p[2])
+        {
+            options->ce.connect_retry_seconds_max =
+                max_int(positive_atoi(p[2]), options->ce.connect_retry_seconds);
+        }
+    }
+    else if ((streq(p[0], "connect-timeout") || streq(p[0], "server-poll-timeout"))
+             && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.connect_timeout = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "connect-retry-max") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->connect_retry_max = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "ipchange") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options,
+                        &options->ipchange,
+                        string_substitute(p[1], ',', ' ', &options->gc),
+                        "ipchange", true);
+    }
+    else if (streq(p[0], "float") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.remote_float = true;
+    }
+#ifdef ENABLE_DEBUG
+    else if (streq(p[0], "gremlin") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->gremlin = positive_atoi(p[1]);
+    }
+#endif
+    else if (streq(p[0], "chroot") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->chroot_dir = p[1];
+    }
+    else if (streq(p[0], "cd") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (platform_chdir(p[1]))
+        {
+            msg(M_ERR, "cd to '%s' failed", p[1]);
+            goto err;
+        }
+        options->cd_dir = p[1];
+    }
+#ifdef ENABLE_SELINUX
+    else if (streq(p[0], "setcon") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->selinux_context = p[1];
+    }
+#endif
+    else if (streq(p[0], "writepid") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->writepid = p[1];
+    }
+    else if (streq(p[0], "up") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->up_script, p[1], "up", false);
+    }
+    else if (streq(p[0], "down") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->down_script, p[1], "down", true);
+    }
+    else if (streq(p[0], "down-pre") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->down_pre = true;
+    }
+    else if (streq(p[0], "up-delay") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->up_delay = true;
+    }
+    else if (streq(p[0], "up-restart") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->up_restart = true;
+    }
+    else if (streq(p[0], "syslog") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        open_syslog(p[1], false);
+    }
+    else if (streq(p[0], "daemon") && !p[2])
+    {
+        bool didit = false;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (!options->daemon)
+        {
+            options->daemon = didit = true;
+            open_syslog(p[1], false);
+        }
+        if (p[1])
+        {
+            if (!didit)
+            {
+                msg(M_WARN, "WARNING: Multiple --daemon directives specified, ignoring --daemon %s. (Note that initscripts sometimes add their own --daemon directive.)", p[1]);
+                goto err;
+            }
+        }
+    }
+    else if (streq(p[0], "inetd") && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (!options->inetd)
+        {
+            int z;
+            const char *name = NULL;
+            const char *opterr = "when --inetd is used with two parameters, one of them must be 'wait' or 'nowait' and the other must be a daemon name to use for system logging";
+
+            options->inetd = -1;
+
+            for (z = 1; z <= 2; ++z)
+            {
+                if (p[z])
+                {
+                    if (streq(p[z], "wait"))
+                    {
+                        if (options->inetd != -1)
+                        {
+                            msg(msglevel, "%s", opterr);
+                            goto err;
+                        }
+                        else
+                        {
+                            options->inetd = INETD_WAIT;
+                        }
+                    }
+                    else if (streq(p[z], "nowait"))
+                    {
+                        if (options->inetd != -1)
+                        {
+                            msg(msglevel, "%s", opterr);
+                            goto err;
+                        }
+                        else
+                        {
+                            options->inetd = INETD_NOWAIT;
+                        }
+                    }
+                    else
+                    {
+                        if (name != NULL)
+                        {
+                            msg(msglevel, "%s", opterr);
+                            goto err;
+                        }
+                        name = p[z];
+                    }
+                }
+            }
+
+            /* default */
+            if (options->inetd == -1)
+            {
+                options->inetd = INETD_WAIT;
+            }
+
+            save_inetd_socket_descriptor();
+            open_syslog(name, true);
+        }
+    }
+    else if (streq(p[0], "log") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->log = true;
+        redirect_stdout_stderr(p[1], false);
+    }
+    else if (streq(p[0], "suppress-timestamps") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->suppress_timestamps = true;
+        set_suppress_timestamps(true);
+    }
+    else if (streq(p[0], "machine-readable-output") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->machine_readable_output = true;
+        set_machine_readable_output(true);
+    }
+    else if (streq(p[0], "log-append") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->log = true;
+        redirect_stdout_stderr(p[1], true);
+    }
+#ifdef ENABLE_MEMSTATS
+    else if (streq(p[0], "memstats") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->memstats_fn = p[1];
+    }
+#endif
+    else if (streq(p[0], "mlock") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->mlock = true;
+    }
+#if ENABLE_IP_PKTINFO
+    else if (streq(p[0], "multihome") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->sockflags |= SF_USE_IP_PKTINFO;
+    }
+#endif
+    else if (streq(p[0], "verb") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MESSAGES);
+        options->verbosity = positive_atoi(p[1]);
+#if !defined(ENABLE_DEBUG) && !defined(ENABLE_SMALL)
+        /* Warn when a debug verbosity is supplied when built without debug support */
+        if (options->verbosity >= 7)
+        {
+            msg(M_WARN, "NOTE: debug verbosity (--verb %d) is enabled but this build lacks debug support.",
+                options->verbosity);
+        }
+#endif
+    }
+    else if (streq(p[0], "mute") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MESSAGES);
+        options->mute = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "errors-to-stderr") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_MESSAGES);
+        errors_to_stderr();
+    }
+    else if (streq(p[0], "status") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->status_file = p[1];
+        if (p[2])
+        {
+            options->status_file_update_freq = positive_atoi(p[2]);
+        }
+    }
+    else if (streq(p[0], "status-version") && p[1] && !p[2])
+    {
+        int version;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        version = atoi(p[1]);
+        if (version < 1 || version > 3)
+        {
+            msg(msglevel, "--status-version must be 1 to 3");
+            goto err;
+        }
+        options->status_file_version = version;
+    }
+    else if (streq(p[0], "remap-usr1") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "SIGHUP"))
+        {
+            options->remap_sigusr1 = SIGHUP;
+        }
+        else if (streq(p[1], "SIGTERM"))
+        {
+            options->remap_sigusr1 = SIGTERM;
+        }
+        else
+        {
+            msg(msglevel, "--remap-usr1 parm must be 'SIGHUP' or 'SIGTERM'");
+            goto err;
+        }
+    }
+    else if ((streq(p[0], "link-mtu") || streq(p[0], "udp-mtu")) && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        options->ce.link_mtu = positive_atoi(p[1]);
+        options->ce.link_mtu_defined = true;
+    }
+    else if (streq(p[0], "tun-mtu") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        options->ce.tun_mtu = positive_atoi(p[1]);
+        options->ce.tun_mtu_defined = true;
+    }
+    else if (streq(p[0], "tun-mtu-extra") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        options->ce.tun_mtu_extra = positive_atoi(p[1]);
+        options->ce.tun_mtu_extra_defined = true;
+    }
+#ifdef ENABLE_FRAGMENT
+    else if (streq(p[0], "mtu-dynamic"))
+    {
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        msg(msglevel, "--mtu-dynamic has been replaced by --fragment");
+        goto err;
+    }
+    else if (streq(p[0], "fragment") && p[1] && !p[2])
+    {
+/*      VERIFY_PERMISSION (OPT_P_MTU); */
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        options->ce.fragment = positive_atoi(p[1]);
+    }
+#endif
+    else if (streq(p[0], "mtu-disc") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_MTU|OPT_P_CONNECTION);
+        options->ce.mtu_discover_type = translate_mtu_discover_type_name(p[1]);
+    }
+#ifdef ENABLE_OCC
+    else if (streq(p[0], "mtu-test") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->mtu_test = true;
+    }
+#endif
+    else if (streq(p[0], "nice") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_NICE);
+        options->nice = atoi(p[1]);
+    }
+    else if (streq(p[0], "rcvbuf") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_SOCKBUF);
+        options->rcvbuf = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "sndbuf") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_SOCKBUF);
+        options->sndbuf = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "mark") && p[1] && !p[2])
+    {
+#if defined(TARGET_LINUX) && HAVE_DECL_SO_MARK
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->mark = atoi(p[1]);
+#endif
+    }
+    else if (streq(p[0], "socket-flags"))
+    {
+        int j;
+        VERIFY_PERMISSION(OPT_P_SOCKFLAGS);
+        for (j = 1; j < MAX_PARMS && p[j]; ++j)
+        {
+            if (streq(p[j], "TCP_NODELAY"))
+            {
+                options->sockflags |= SF_TCP_NODELAY;
+            }
+            else
+            {
+                msg(msglevel, "unknown socket flag: %s", p[j]);
+            }
+        }
+    }
+    else if (streq(p[0], "txqueuelen") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+#ifdef TARGET_LINUX
+        options->tuntap_options.txqueuelen = positive_atoi(p[1]);
+#else
+        msg(msglevel, "--txqueuelen not supported on this OS");
+        goto err;
+#endif
+    }
+    else if (streq(p[0], "shaper") && p[1] && !p[2])
+    {
+#ifdef ENABLE_FEATURE_SHAPER
+        int shaper;
+
+        VERIFY_PERMISSION(OPT_P_SHAPER);
+        shaper = atoi(p[1]);
+        if (shaper < SHAPER_MIN || shaper > SHAPER_MAX)
+        {
+            msg(msglevel, "Bad shaper value, must be between %d and %d",
+                SHAPER_MIN, SHAPER_MAX);
+            goto err;
+        }
+        options->shaper = shaper;
+#else /* ENABLE_FEATURE_SHAPER */
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        msg(msglevel, "--shaper requires the gettimeofday() function which is missing");
+        goto err;
+#endif /* ENABLE_FEATURE_SHAPER */
+    }
+    else if (streq(p[0], "port") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.local_port = options->ce.remote_port = p[1];
+    }
+    else if (streq(p[0], "lport") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.local_port_defined = true;
+        options->ce.local_port = p[1];
+    }
+    else if (streq(p[0], "rport") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.remote_port = p[1];
+    }
+    else if (streq(p[0], "bind") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.bind_defined = true;
+        if (p[1] && streq(p[1], "ipv6only"))
+        {
+            options->ce.bind_ipv6_only = true;
+        }
+
+    }
+    else if (streq(p[0], "nobind") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        options->ce.bind_local = false;
+    }
+    else if (streq(p[0], "fast-io") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->fast_io = true;
+    }
+    else if (streq(p[0], "inactive") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_TIMER);
+        options->inactivity_timeout = positive_atoi(p[1]);
+        if (p[2])
+        {
+            options->inactivity_minimum_bytes = positive_atoi(p[2]);
+        }
+    }
+    else if (streq(p[0], "proto") && p[1] && !p[2])
+    {
+        int proto;
+        sa_family_t af;
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        proto = ascii2proto(p[1]);
+        af = ascii2af(p[1]);
+        if (proto < 0)
+        {
+            msg(msglevel, "Bad protocol: '%s'.  Allowed protocols with --proto option: %s",
+                p[1],
+                proto2ascii_all(&gc));
+            goto err;
+        }
+        options->ce.proto = proto;
+        options->ce.af = af;
+    }
+    else if (streq(p[0], "proto-force") && p[1] && !p[2])
+    {
+        int proto_force;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        proto_force = ascii2proto(p[1]);
+        if (proto_force < 0)
+        {
+            msg(msglevel, "Bad --proto-force protocol: '%s'", p[1]);
+            goto err;
+        }
+        options->proto_force = proto_force;
+    }
+    else if (streq(p[0], "http-proxy") && p[1] && !p[5])
+    {
+        struct http_proxy_options *ho;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+
+        {
+            if (!p[2])
+            {
+                msg(msglevel, "http-proxy port number not defined");
+                goto err;
+            }
+
+            ho = init_http_proxy_options_once(&options->ce.http_proxy_options, &options->gc);
+
+            ho->server = p[1];
+            ho->port = p[2];
+        }
+
+        if (p[3])
+        {
+            /* auto -- try to figure out proxy addr, port, and type automatically */
+            /* semiauto -- given proxy addr:port, try to figure out type automatically */
+            /* (auto|semiauto)-nct -- disable proxy auth cleartext protocols (i.e. basic auth) */
+            if (streq(p[3], "auto"))
+            {
+                ho->auth_retry = PAR_ALL;
+            }
+            else if (streq(p[3], "auto-nct"))
+            {
+                ho->auth_retry = PAR_NCT;
+            }
+            else
+            {
+                ho->auth_method_string = "basic";
+                ho->auth_file = p[3];
+
+                if (p[4])
+                {
+                    ho->auth_method_string = p[4];
+                }
+            }
+        }
+        else
+        {
+            ho->auth_method_string = "none";
+        }
+    }
+    else if (streq(p[0], "http-proxy-user-pass") && p[1])
+    {
+        struct http_proxy_options *ho;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ho = init_http_proxy_options_once(&options->ce.http_proxy_options, &options->gc);
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            ho->auth_file = p[2];
+            ho->inline_creds = true;
+        }
+        else
+        {
+            ho->auth_file = p[1];
+        }
+    }
+    else if (streq(p[0], "http-proxy-retry") || streq(p[0], "socks-proxy-retry"))
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        msg(M_WARN, "DEPRECATED OPTION: http-proxy-retry and socks-proxy-retry: "
+            "In OpenVPN 2.4 proxy connection retries are handled like regular connections. "
+            "Use connect-retry-max 1 to get a similar behavior as before.");
+    }
+    else if (streq(p[0], "http-proxy-timeout") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        msg(M_WARN, "DEPRECATED OPTION: http-proxy-timeout: In OpenVPN 2.4 the timeout until a connection to a "
+            "server is established is managed with a single timeout set by connect-timeout");
+    }
+    else if (streq(p[0], "http-proxy-option") && p[1] && !p[4])
+    {
+        struct http_proxy_options *ho;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        ho = init_http_proxy_options_once(&options->ce.http_proxy_options, &options->gc);
+
+        if (streq(p[1], "VERSION") && p[2] && !p[3])
+        {
+            ho->http_version = p[2];
+        }
+        else if (streq(p[1], "AGENT") && p[2] && !p[3])
+        {
+            ho->user_agent = p[2];
+        }
+        else if ((streq(p[1], "EXT1") || streq(p[1], "EXT2") || streq(p[1], "CUSTOM-HEADER"))
+                 && p[2])
+        {
+            /* In the wild patched versions use both EXT1/2 and CUSTOM-HEADER
+             * with either two argument or one */
+
+            struct http_custom_header *custom_header = NULL;
+            int i;
+            /* Find the first free header */
+            for (i = 0; i < MAX_CUSTOM_HTTP_HEADER; i++)
+            {
+                if (!ho->custom_headers[i].name)
+                {
+                    custom_header = &ho->custom_headers[i];
+                    break;
+                }
+            }
+            if (!custom_header)
+            {
+                msg(msglevel, "Cannot use more than %d http-proxy-option CUSTOM-HEADER : '%s'", MAX_CUSTOM_HTTP_HEADER, p[1]);
+            }
+            else
+            {
+                /* We will save p[2] and p[3], the proxy code will detect if
+                 * p[3] is NULL */
+                custom_header->name = p[2];
+                custom_header->content = p[3];
+            }
+        }
+        else
+        {
+            msg(msglevel, "Bad http-proxy-option or missing or extra parameter: '%s'", p[1]);
+        }
+    }
+    else if (streq(p[0], "socks-proxy") && p[1] && !p[4])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+
+        if (p[2])
+        {
+            options->ce.socks_proxy_port = p[2];
+        }
+        else
+        {
+            options->ce.socks_proxy_port = "1080";
+        }
+        options->ce.socks_proxy_server = p[1];
+        options->ce.socks_proxy_authfile = p[3]; /* might be NULL */
+    }
+    else if (streq(p[0], "keepalive") && p[1] && p[2] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->keepalive_ping = atoi(p[1]);
+        options->keepalive_timeout = atoi(p[2]);
+    }
+    else if (streq(p[0], "ping") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TIMER);
+        options->ping_send_timeout = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "ping-exit") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TIMER);
+        options->ping_rec_timeout = positive_atoi(p[1]);
+        options->ping_rec_timeout_action = PING_EXIT;
+    }
+    else if (streq(p[0], "ping-restart") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TIMER);
+        options->ping_rec_timeout = positive_atoi(p[1]);
+        options->ping_rec_timeout_action = PING_RESTART;
+    }
+    else if (streq(p[0], "ping-timer-rem") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_TIMER);
+        options->ping_timer_remote = true;
+    }
+#ifdef ENABLE_OCC
+    else if (streq(p[0], "explicit-exit-notify") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION|OPT_P_EXPLICIT_NOTIFY);
+        if (p[1])
+        {
+            options->ce.explicit_exit_notification = positive_atoi(p[1]);
+        }
+        else
+        {
+            options->ce.explicit_exit_notification = 1;
+        }
+    }
+#endif
+    else if (streq(p[0], "persist-tun") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_PERSIST);
+        options->persist_tun = true;
+    }
+    else if (streq(p[0], "persist-key") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_PERSIST);
+        options->persist_key = true;
+    }
+    else if (streq(p[0], "persist-local-ip") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_PERSIST_IP);
+        options->persist_local_ip = true;
+    }
+    else if (streq(p[0], "persist-remote-ip") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_PERSIST_IP);
+        options->persist_remote_ip = true;
+    }
+    else if (streq(p[0], "client-nat") && p[1] && p[2] && p[3] && p[4] && !p[5])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE);
+        cnol_check_alloc(options);
+        add_client_nat_to_option_list(options->client_nat, p[1], p[2], p[3], p[4], msglevel);
+    }
+    else if (streq(p[0], "route") && p[1] && !p[5])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE);
+        rol_check_alloc(options);
+        if (pull_mode)
+        {
+            if (!ip_or_dns_addr_safe(p[1], options->allow_pull_fqdn) && !is_special_addr(p[1])) /* FQDN -- may be DNS name */
+            {
+                msg(msglevel, "route parameter network/IP '%s' must be a valid address", p[1]);
+                goto err;
+            }
+            if (p[2] && !ip_addr_dotted_quad_safe(p[2])) /* FQDN -- must be IP address */
+            {
+                msg(msglevel, "route parameter netmask '%s' must be an IP address", p[2]);
+                goto err;
+            }
+            if (p[3] && !ip_or_dns_addr_safe(p[3], options->allow_pull_fqdn) && !is_special_addr(p[3])) /* FQDN -- may be DNS name */
+            {
+                msg(msglevel, "route parameter gateway '%s' must be a valid address", p[3]);
+                goto err;
+            }
+        }
+        add_route_to_option_list(options->routes, p[1], p[2], p[3], p[4]);
+    }
+    else if (streq(p[0], "route-ipv6") && p[1] && !p[4])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE);
+        rol6_check_alloc(options);
+        if (pull_mode)
+        {
+            if (!ipv6_addr_safe_hexplusbits(p[1]))
+            {
+                msg(msglevel, "route-ipv6 parameter network/IP '%s' must be a valid address", p[1]);
+                goto err;
+            }
+            if (p[2] && !ipv6_addr_safe(p[2]))
+            {
+                msg(msglevel, "route-ipv6 parameter gateway '%s' must be a valid address", p[2]);
+                goto err;
+            }
+            /* p[3] is metric, if present */
+        }
+        add_route_ipv6_to_option_list(options->routes_ipv6, p[1], p[2], p[3]);
+    }
+    else if (streq(p[0], "max-routes") && !p[2])
+    {
+        msg(M_WARN, "DEPRECATED OPTION: --max-routes option ignored."
+            "The number of routes is unlimited as of OpenVPN 2.4. "
+            "This option will be removed in a future version, "
+            "please remove it from your configuration.");
+    }
+    else if (streq(p[0], "route-gateway") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE_EXTRAS);
+        if (streq(p[1], "dhcp"))
+        {
+            options->route_gateway_via_dhcp = true;
+        }
+        else
+        {
+            if (ip_or_dns_addr_safe(p[1], options->allow_pull_fqdn) || is_special_addr(p[1])) /* FQDN -- may be DNS name */
+            {
+                options->route_default_gateway = p[1];
+            }
+            else
+            {
+                msg(msglevel, "route-gateway parm '%s' must be a valid address", p[1]);
+                goto err;
+            }
+        }
+    }
+    else if (streq(p[0], "route-metric") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE);
+        options->route_default_metric = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "route-delay") && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE_EXTRAS);
+        options->route_delay_defined = true;
+        if (p[1])
+        {
+            options->route_delay = positive_atoi(p[1]);
+            if (p[2])
+            {
+                options->route_delay_window = positive_atoi(p[2]);
+            }
+        }
+        else
+        {
+            options->route_delay = 0;
+        }
+    }
+    else if (streq(p[0], "route-up") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->route_script, p[1], "route-up", false);
+    }
+    else if (streq(p[0], "route-pre-down") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options,
+                        &options->route_predown_script,
+                        p[1],
+                        "route-pre-down", true);
+    }
+    else if (streq(p[0], "route-noexec") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        options->route_noexec = true;
+    }
+    else if (streq(p[0], "route-nopull") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->route_nopull = true;
+    }
+    else if (streq(p[0], "pull-filter") && p[1] && p[2] && !p[3])
+    {
+        struct pull_filter *f;
+        VERIFY_PERMISSION(OPT_P_GENERAL)
+        f = alloc_pull_filter(options, msglevel);
+
+        if (strcmp("accept", p[1]) == 0)
+        {
+            f->type = PUF_TYPE_ACCEPT;
+        }
+        else if (strcmp("ignore", p[1]) == 0)
+        {
+            f->type = PUF_TYPE_IGNORE;
+        }
+        else if (strcmp("reject", p[1]) == 0)
+        {
+            f->type = PUF_TYPE_REJECT;
+        }
+        else
+        {
+            msg(msglevel, "Unknown --pull-filter type: %s", p[1]);
+            goto err;
+        }
+        f->pattern = p[2];
+        f->size = strlen(p[2]);
+    }
+    else if (streq(p[0], "allow-pull-fqdn") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->allow_pull_fqdn = true;
+    }
+    else if (streq(p[0], "redirect-gateway") || streq(p[0], "redirect-private"))
+    {
+        int j;
+        VERIFY_PERMISSION(OPT_P_ROUTE);
+        rol_check_alloc(options);
+        if (streq(p[0], "redirect-gateway"))
+        {
+            options->routes->flags |= RG_REROUTE_GW;
+        }
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            if (streq(p[j], "local"))
+            {
+                options->routes->flags |= RG_LOCAL;
+            }
+            else if (streq(p[j], "autolocal"))
+            {
+                options->routes->flags |= RG_AUTO_LOCAL;
+            }
+            else if (streq(p[j], "def1"))
+            {
+                options->routes->flags |= RG_DEF1;
+            }
+            else if (streq(p[j], "bypass-dhcp"))
+            {
+                options->routes->flags |= RG_BYPASS_DHCP;
+            }
+            else if (streq(p[j], "bypass-dns"))
+            {
+                options->routes->flags |= RG_BYPASS_DNS;
+            }
+            else if (streq(p[j], "block-local"))
+            {
+                options->routes->flags |= RG_BLOCK_LOCAL;
+            }
+            else if (streq(p[j], "ipv6"))
+            {
+                rol6_check_alloc(options);
+                options->routes_ipv6->flags |= RG_REROUTE_GW;
+            }
+            else if (streq(p[j], "!ipv4"))
+            {
+                options->routes->flags &= ~RG_REROUTE_GW;
+            }
+            else
+            {
+                msg(msglevel, "unknown --%s flag: %s", p[0], p[j]);
+                goto err;
+            }
+        }
+#ifdef _WIN32
+        /* we need this here to handle pushed --redirect-gateway */
+        remap_redirect_gateway_flags(options);
+#endif
+        options->routes->flags |= RG_ENABLE;
+    }
+    else if (streq(p[0], "remote-random-hostname") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->sockflags |= SF_HOST_RANDOMIZE;
+    }
+    else if (streq(p[0], "setenv") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "REMOTE_RANDOM_HOSTNAME") && !p[2])
+        {
+            options->sockflags |= SF_HOST_RANDOMIZE;
+        }
+        else if (streq(p[1], "GENERIC_CONFIG"))
+        {
+            msg(msglevel, "this is a generic configuration and cannot directly be used");
+            goto err;
+        }
+#ifdef ENABLE_PUSH_PEER_INFO
+        else if (streq(p[1], "PUSH_PEER_INFO") && !p[2])
+        {
+            options->push_peer_info = true;
+        }
+#endif
+        else if (streq(p[1], "SERVER_POLL_TIMEOUT") && p[2])
+        {
+            options->ce.connect_timeout = positive_atoi(p[2]);
+        }
+        else
+        {
+            if (streq(p[1], "FORWARD_COMPATIBLE") && p[2] && streq(p[2], "1"))
+            {
+                options->forward_compatible = true;
+                msglevel_fc = msglevel_forward_compatible(options, msglevel);
+            }
+            setenv_str(es, p[1], p[2] ? p[2] : "");
+        }
+    }
+    else if (streq(p[0], "setenv-safe") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_SETENV);
+        setenv_str_safe(es, p[1], p[2] ? p[2] : "");
+    }
+    else if (streq(p[0], "script-security") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        script_security = atoi(p[1]);
+    }
+    else if (streq(p[0], "mssfix") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_CONNECTION);
+        if (p[1])
+        {
+            options->ce.mssfix = positive_atoi(p[1]);
+        }
+        else
+        {
+            options->ce.mssfix_default = true;
+        }
+
+    }
+#ifdef ENABLE_OCC
+    else if (streq(p[0], "disable-occ") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->occ = false;
+    }
+#endif
+#if P2MP
+#if P2MP_SERVER
+    else if (streq(p[0], "server") && p[1] && p[2] && !p[4])
+    {
+        const int lev = M_WARN;
+        bool error = false;
+        in_addr_t network, netmask;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        network = get_ip_addr(p[1], lev, &error);
+        netmask = get_ip_addr(p[2], lev, &error);
+        if (error || !network || !netmask)
+        {
+            msg(msglevel, "error parsing --server parameters");
+            goto err;
+        }
+        options->server_defined = true;
+        options->server_network = network;
+        options->server_netmask = netmask;
+
+        if (p[3])
+        {
+            if (streq(p[3], "nopool"))
+            {
+                options->server_flags |= SF_NOPOOL;
+            }
+            else
+            {
+                msg(msglevel, "error parsing --server: %s is not a recognized flag", p[3]);
+                goto err;
+            }
+        }
+    }
+    else if (streq(p[0], "server-ipv6") && p[1] && !p[3])
+    {
+        const int lev = M_WARN;
+        struct in6_addr network;
+        unsigned int netbits = 0;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (!get_ipv6_addr(p[1], &network, &netbits, lev) )
+        {
+            msg(msglevel, "error parsing --server-ipv6 parameter");
+            goto err;
+        }
+        if (netbits < 64 || netbits > 112)
+        {
+            msg( msglevel, "--server-ipv6 settings: only /64../112 supported right now (not /%d)", netbits );
+            goto err;
+        }
+        options->server_ipv6_defined = true;
+        options->server_network_ipv6 = network;
+        options->server_netbits_ipv6 = netbits;
+
+        if (p[2])       /* no "nopool" options or similar for IPv6 */
+        {
+            msg(msglevel, "error parsing --server-ipv6: %s is not a recognized flag", p[3]);
+            goto err;
+        }
+    }
+    else if (streq(p[0], "server-bridge") && p[1] && p[2] && p[3] && p[4] && !p[5])
+    {
+        const int lev = M_WARN;
+        bool error = false;
+        in_addr_t ip, netmask, pool_start, pool_end;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ip = get_ip_addr(p[1], lev, &error);
+        netmask = get_ip_addr(p[2], lev, &error);
+        pool_start = get_ip_addr(p[3], lev, &error);
+        pool_end = get_ip_addr(p[4], lev, &error);
+        if (error || !ip || !netmask || !pool_start || !pool_end)
+        {
+            msg(msglevel, "error parsing --server-bridge parameters");
+            goto err;
+        }
+        options->server_bridge_defined = true;
+        options->server_bridge_ip = ip;
+        options->server_bridge_netmask = netmask;
+        options->server_bridge_pool_start = pool_start;
+        options->server_bridge_pool_end = pool_end;
+    }
+    else if (streq(p[0], "server-bridge") && p[1] && streq(p[1], "nogw") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->server_bridge_proxy_dhcp = true;
+        options->server_flags |= SF_NO_PUSH_ROUTE_GATEWAY;
+    }
+    else if (streq(p[0], "server-bridge") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->server_bridge_proxy_dhcp = true;
+    }
+    else if (streq(p[0], "push") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_PUSH);
+        push_options(options, &p[1], msglevel, &options->gc);
+    }
+    else if (streq(p[0], "push-reset") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        push_reset(options);
+    }
+    else if (streq(p[0], "push-remove") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        msg(D_PUSH, "PUSH_REMOVE '%s'", p[1]);
+        push_remove_option(options,p[1]);
+    }
+    else if (streq(p[0], "ifconfig-pool") && p[1] && p[2] && !p[4])
+    {
+        const int lev = M_WARN;
+        bool error = false;
+        in_addr_t start, end, netmask = 0;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        start = get_ip_addr(p[1], lev, &error);
+        end = get_ip_addr(p[2], lev, &error);
+        if (p[3])
+        {
+            netmask = get_ip_addr(p[3], lev, &error);
+        }
+        if (error)
+        {
+            msg(msglevel, "error parsing --ifconfig-pool parameters");
+            goto err;
+        }
+        if (!ifconfig_pool_verify_range(msglevel, start, end))
+        {
+            goto err;
+        }
+
+        options->ifconfig_pool_defined = true;
+        options->ifconfig_pool_start = start;
+        options->ifconfig_pool_end = end;
+        if (netmask)
+        {
+            options->ifconfig_pool_netmask = netmask;
+        }
+    }
+    else if (streq(p[0], "ifconfig-pool-persist") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ifconfig_pool_persist_filename = p[1];
+        if (p[2])
+        {
+            options->ifconfig_pool_persist_refresh_freq = positive_atoi(p[2]);
+        }
+    }
+    else if (streq(p[0], "ifconfig-pool-linear") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->topology = TOP_P2P;
+        msg(M_WARN, "DEPRECATED OPTION: --ifconfig-pool-linear, use --topology p2p instead");
+    }
+    else if (streq(p[0], "ifconfig-ipv6-pool") && p[1] && !p[2])
+    {
+        const int lev = M_WARN;
+        struct in6_addr network;
+        unsigned int netbits = 0;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (!get_ipv6_addr(p[1], &network, &netbits, lev ) )
+        {
+            msg(msglevel, "error parsing --ifconfig-ipv6-pool parameters");
+            goto err;
+        }
+        if (netbits < 64 || netbits > 112)
+        {
+            msg( msglevel, "--ifconfig-ipv6-pool settings: only /64../112 supported right now (not /%d)", netbits );
+            goto err;
+        }
+
+        options->ifconfig_ipv6_pool_defined = true;
+        options->ifconfig_ipv6_pool_base = network;
+        options->ifconfig_ipv6_pool_netbits = netbits;
+    }
+    else if (streq(p[0], "hash-size") && p[1] && p[2] && !p[3])
+    {
+        int real, virtual;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        real = atoi(p[1]);
+        virtual = atoi(p[2]);
+        if (real < 1 || virtual < 1)
+        {
+            msg(msglevel, "--hash-size sizes must be >= 1 (preferably a power of 2)");
+            goto err;
+        }
+        options->real_hash_size = real;
+        options->virtual_hash_size = real;
+    }
+    else if (streq(p[0], "connect-freq") && p[1] && p[2] && !p[3])
+    {
+        int cf_max, cf_per;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        cf_max = atoi(p[1]);
+        cf_per = atoi(p[2]);
+        if (cf_max < 0 || cf_per < 0)
+        {
+            msg(msglevel, "--connect-freq parms must be > 0");
+            goto err;
+        }
+        options->cf_max = cf_max;
+        options->cf_per = cf_per;
+    }
+    else if (streq(p[0], "max-clients") && p[1] && !p[2])
+    {
+        int max_clients;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        max_clients = atoi(p[1]);
+        if (max_clients < 0)
+        {
+            msg(msglevel, "--max-clients must be at least 1");
+            goto err;
+        }
+        if (max_clients >= MAX_PEER_ID) /* max peer-id value */
+        {
+            msg(msglevel, "--max-clients must be less than %d", MAX_PEER_ID);
+            goto err;
+        }
+        options->max_clients = max_clients;
+    }
+    else if (streq(p[0], "max-routes-per-client") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_INHERIT);
+        options->max_routes_per_client = max_int(atoi(p[1]), 1);
+    }
+    else if (streq(p[0], "client-cert-not-required") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ssl_flags |= SSLF_CLIENT_CERT_NOT_REQUIRED;
+        msg(M_WARN, "DEPRECATED OPTION: --client-cert-not-required, use --verify-client-cert instead");
+    }
+    else if (streq(p[0], "verify-client-cert") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        /* Reset any existing flags */
+        options->ssl_flags &= ~SSLF_CLIENT_CERT_OPTIONAL;
+        options->ssl_flags &= ~SSLF_CLIENT_CERT_NOT_REQUIRED;
+        if (p[1])
+        {
+            if (streq(p[1], "none"))
+            {
+                options->ssl_flags |= SSLF_CLIENT_CERT_NOT_REQUIRED;
+            }
+            else if (streq(p[1], "optional"))
+            {
+                options->ssl_flags |= SSLF_CLIENT_CERT_OPTIONAL;
+            }
+            else if (!streq(p[1], "require"))
+            {
+                msg(msglevel, "parameter to --verify-client-cert must be 'none', 'optional' or 'require'");
+                goto err;
+            }
+        }
+    }
+    else if (streq(p[0], "username-as-common-name") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ssl_flags |= SSLF_USERNAME_AS_COMMON_NAME;
+    }
+    else if (streq(p[0], "auth-user-pass-optional") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ssl_flags |= SSLF_AUTH_USER_PASS_OPTIONAL;
+    }
+    else if (streq(p[0], "opt-verify") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ssl_flags |= SSLF_OPT_VERIFY;
+    }
+    else if (streq(p[0], "auth-user-pass-verify") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 3, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        if (p[2])
+        {
+            if (streq(p[2], "via-env"))
+            {
+                options->auth_user_pass_verify_script_via_file = false;
+            }
+            else if (streq(p[2], "via-file"))
+            {
+                options->auth_user_pass_verify_script_via_file = true;
+            }
+            else
+            {
+                msg(msglevel, "second parm to --auth-user-pass-verify must be 'via-env' or 'via-file'");
+                goto err;
+            }
+        }
+        else
+        {
+            msg(msglevel, "--auth-user-pass-verify requires a second parameter ('via-env' or 'via-file')");
+            goto err;
+        }
+        set_user_script(options,
+                        &options->auth_user_pass_verify_script,
+                        p[1], "auth-user-pass-verify", true);
+    }
+    else if (streq(p[0], "auth-gen-token"))
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->auth_token_generate = true;
+        options->auth_token_lifetime = p[1] ? positive_atoi(p[1]) : 0;
+    }
+    else if (streq(p[0], "client-connect") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->client_connect_script,
+                        p[1], "client-connect", true);
+    }
+    else if (streq(p[0], "client-disconnect") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->client_disconnect_script,
+                        p[1], "client-disconnect", true);
+    }
+    else if (streq(p[0], "learn-address") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->learn_address_script,
+                        p[1], "learn-address", true);
+    }
+    else if (streq(p[0], "tmp-dir") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tmp_dir = p[1];
+    }
+    else if (streq(p[0], "client-config-dir") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->client_config_dir = p[1];
+    }
+    else if (streq(p[0], "ccd-exclusive") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ccd_exclusive = true;
+    }
+    else if (streq(p[0], "bcast-buffers") && p[1] && !p[2])
+    {
+        int n_bcast_buf;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        n_bcast_buf = atoi(p[1]);
+        if (n_bcast_buf < 1)
+        {
+            msg(msglevel, "--bcast-buffers parameter must be > 0");
+        }
+        options->n_bcast_buf = n_bcast_buf;
+    }
+    else if (streq(p[0], "tcp-queue-limit") && p[1] && !p[2])
+    {
+        int tcp_queue_limit;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        tcp_queue_limit = atoi(p[1]);
+        if (tcp_queue_limit < 1)
+        {
+            msg(msglevel, "--tcp-queue-limit parameter must be > 0");
+        }
+        options->tcp_queue_limit = tcp_queue_limit;
+    }
+#if PORT_SHARE
+    else if (streq(p[0], "port-share") && p[1] && p[2] && !p[4])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->port_share_host = p[1];
+        options->port_share_port = p[2];
+        options->port_share_journal_dir = p[3];
+    }
+#endif
+    else if (streq(p[0], "client-to-client") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->enable_c2c = true;
+    }
+    else if (streq(p[0], "duplicate-cn") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->duplicate_cn = true;
+    }
+    else if (streq(p[0], "iroute") && p[1] && !p[3])
+    {
+        const char *netmask = NULL;
+
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        if (p[2])
+        {
+            netmask = p[2];
+        }
+        option_iroute(options, p[1], netmask, msglevel);
+    }
+    else if (streq(p[0], "iroute-ipv6") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        option_iroute_ipv6(options, p[1], msglevel);
+    }
+    else if (streq(p[0], "ifconfig-push") && p[1] && p[2] && !p[4])
+    {
+        in_addr_t local, remote_netmask;
+
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        local = getaddr(GETADDR_HOST_ORDER|GETADDR_RESOLVE, p[1], 0, NULL, NULL);
+        remote_netmask = getaddr(GETADDR_HOST_ORDER|GETADDR_RESOLVE, p[2], 0, NULL, NULL);
+        if (local && remote_netmask)
+        {
+            options->push_ifconfig_defined = true;
+            options->push_ifconfig_local = local;
+            options->push_ifconfig_remote_netmask = remote_netmask;
+            if (p[3])
+            {
+                options->push_ifconfig_local_alias = getaddr(GETADDR_HOST_ORDER|GETADDR_RESOLVE, p[3], 0, NULL, NULL);
+            }
+        }
+        else
+        {
+            msg(msglevel, "cannot parse --ifconfig-push addresses");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "ifconfig-push-constraint") && p[1] && p[2] && !p[3])
+    {
+        in_addr_t network, netmask;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        network = getaddr(GETADDR_HOST_ORDER|GETADDR_RESOLVE, p[1], 0, NULL, NULL);
+        netmask = getaddr(GETADDR_HOST_ORDER, p[2], 0, NULL, NULL);
+        if (network && netmask)
+        {
+            options->push_ifconfig_constraint_defined = true;
+            options->push_ifconfig_constraint_network = network;
+            options->push_ifconfig_constraint_netmask = netmask;
+        }
+        else
+        {
+            msg(msglevel, "cannot parse --ifconfig-push-constraint addresses");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "ifconfig-ipv6-push") && p[1] && !p[3])
+    {
+        struct in6_addr local, remote;
+        unsigned int netbits;
+
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+
+        if (!get_ipv6_addr( p[1], &local, &netbits, msglevel ) )
+        {
+            msg(msglevel, "cannot parse --ifconfig-ipv6-push addresses");
+            goto err;
+        }
+
+        if (p[2])
+        {
+            if (!get_ipv6_addr( p[2], &remote, NULL, msglevel ) )
+            {
+                msg( msglevel, "cannot parse --ifconfig-ipv6-push addresses");
+                goto err;
+            }
+        }
+        else
+        {
+            if (!options->ifconfig_ipv6_local
+                || !get_ipv6_addr( options->ifconfig_ipv6_local, &remote,
+                                   NULL, msglevel ) )
+            {
+                msg( msglevel, "second argument to --ifconfig-ipv6-push missing and no global --ifconfig-ipv6 address set");
+                goto err;
+            }
+        }
+
+        options->push_ifconfig_ipv6_defined = true;
+        options->push_ifconfig_ipv6_local = local;
+        options->push_ifconfig_ipv6_netbits = netbits;
+        options->push_ifconfig_ipv6_remote = remote;
+        options->push_ifconfig_ipv6_blocked = false;
+    }
+    else if (streq(p[0], "disable") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_INSTANCE);
+        options->disable = true;
+    }
+    else if (streq(p[0], "tcp-nodelay") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->server_flags |= SF_TCP_NODELAY_HELPER;
+    }
+    else if (streq(p[0], "stale-routes-check") && p[1] && !p[3])
+    {
+        int ageing_time, check_interval;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ageing_time = atoi(p[1]);
+        if (p[2])
+        {
+            check_interval = atoi(p[2]);
+        }
+        else
+        {
+            check_interval = ageing_time;
+        }
+
+        if (ageing_time < 1 || check_interval < 1)
+        {
+            msg(msglevel, "--stale-routes-check aging time and check interval must be >= 1");
+            goto err;
+        }
+        options->stale_routes_ageing_time  = ageing_time;
+        options->stale_routes_check_interval = check_interval;
+    }
+#endif /* P2MP_SERVER */
+
+    else if (streq(p[0], "client") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->client = true;
+    }
+    else if (streq(p[0], "pull") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->pull = true;
+    }
+    else if (streq(p[0], "push-continuation") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_PULL_MODE);
+        options->push_continuation = atoi(p[1]);
+    }
+    else if (streq(p[0], "auth-user-pass") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[1])
+        {
+            options->auth_user_pass_file = p[1];
+        }
+        else
+        {
+            options->auth_user_pass_file = "stdin";
+        }
+    }
+    else if (streq(p[0], "auth-retry") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        auth_retry_set(msglevel, p[1]);
+    }
+#ifdef ENABLE_CLIENT_CR
+    else if (streq(p[0], "static-challenge") && p[1] && p[2] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->sc_info.challenge_text = p[1];
+        if (atoi(p[2]))
+        {
+            options->sc_info.flags |= SC_ECHO;
+        }
+    }
+#endif
+#endif /* if P2MP */
+    else if (streq(p[0], "msg-channel") && p[1])
+    {
+#ifdef _WIN32
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        HANDLE process = GetCurrentProcess();
+        HANDLE handle = (HANDLE) atoi(p[1]);
+        if (!DuplicateHandle(process, handle, process, &options->msg_channel, 0,
+                             FALSE, DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS))
+        {
+            msg(msglevel, "could not duplicate service pipe handle");
+            goto err;
+        }
+        options->route_method = ROUTE_METHOD_SERVICE;
+#else  /* ifdef _WIN32 */
+        msg(msglevel, "--msg-channel is only supported on Windows");
+        goto err;
+#endif
+    }
+#ifdef _WIN32
+    else if (streq(p[0], "win-sys") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "env"))
+        {
+            msg(M_INFO, "NOTE: --win-sys env is default from OpenVPN 2.3.	 "
+                "This entry will now be ignored.  "
+                "Please remove this entry from your configuration file.");
+        }
+        else
+        {
+            set_win_sys_path(p[1], es);
+        }
+    }
+    else if (streq(p[0], "route-method") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE_EXTRAS);
+        if (streq(p[1], "adaptive"))
+        {
+            options->route_method = ROUTE_METHOD_ADAPTIVE;
+        }
+        else if (streq(p[1], "ipapi"))
+        {
+            options->route_method = ROUTE_METHOD_IPAPI;
+        }
+        else if (streq(p[1], "exe"))
+        {
+            options->route_method = ROUTE_METHOD_EXE;
+        }
+        else
+        {
+            msg(msglevel, "--route method must be 'adaptive', 'ipapi', or 'exe'");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "ip-win32") && p[1] && !p[4])
+    {
+        const int index = ascii2ipset(p[1]);
+        struct tuntap_options *to = &options->tuntap_options;
+
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+
+        if (index < 0)
+        {
+            msg(msglevel,
+                "Bad --ip-win32 method: '%s'.  Allowed methods: %s",
+                p[1],
+                ipset2ascii_all(&gc));
+            goto err;
+        }
+
+        if (index == IPW32_SET_ADAPTIVE)
+        {
+            options->route_delay_window = IPW32_SET_ADAPTIVE_DELAY_WINDOW;
+        }
+
+        if (index == IPW32_SET_DHCP_MASQ)
+        {
+            if (p[2])
+            {
+                if (!streq(p[2], "default"))
+                {
+                    int offset = atoi(p[2]);
+
+                    if (!(offset > -256 && offset < 256))
+                    {
+                        msg(msglevel, "--ip-win32 dynamic [offset] [lease-time]: offset (%d) must be > -256 and < 256", offset);
+                        goto err;
+                    }
+
+                    to->dhcp_masq_custom_offset = true;
+                    to->dhcp_masq_offset = offset;
+                }
+
+                if (p[3])
+                {
+                    const int min_lease = 30;
+                    int lease_time;
+                    lease_time = atoi(p[3]);
+                    if (lease_time < min_lease)
+                    {
+                        msg(msglevel, "--ip-win32 dynamic [offset] [lease-time]: lease time parameter (%d) must be at least %d seconds", lease_time, min_lease);
+                        goto err;
+                    }
+                    to->dhcp_lease_time = lease_time;
+                }
+            }
+        }
+        to->ip_win32_type = index;
+        to->ip_win32_defined = true;
+    }
+#endif /* ifdef _WIN32 */
+#if defined(_WIN32) || defined(TARGET_ANDROID)
+    else if (streq(p[0], "dhcp-option") && p[1] && !p[3])
+    {
+        struct tuntap_options *o = &options->tuntap_options;
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        bool ipv6dns = false;
+
+        if (streq(p[1], "DOMAIN") && p[2])
+        {
+            o->domain = p[2];
+        }
+        else if (streq(p[1], "NBS") && p[2])
+        {
+            o->netbios_scope = p[2];
+        }
+        else if (streq(p[1], "NBT") && p[2])
+        {
+            int t;
+            t = atoi(p[2]);
+            if (!(t == 1 || t == 2 || t == 4 || t == 8))
+            {
+                msg(msglevel, "--dhcp-option NBT: parameter (%d) must be 1, 2, 4, or 8", t);
+                goto err;
+            }
+            o->netbios_node_type = t;
+        }
+        else if ((streq(p[1], "DNS") || streq(p[1], "DNS6")) && p[2] && (!strstr(p[2], ":") || ipv6_addr_safe(p[2])))
+        {
+            if (strstr(p[2], ":"))
+            {
+                ipv6dns=true;
+                foreign_option(options, p, 3, es);
+                dhcp_option_dns6_parse(p[2], o->dns6, &o->dns6_len, msglevel);
+            }
+            else
+            {
+                dhcp_option_address_parse("DNS", p[2], o->dns, &o->dns_len, msglevel);
+            }
+        }
+        else if (streq(p[1], "WINS") && p[2])
+        {
+            dhcp_option_address_parse("WINS", p[2], o->wins, &o->wins_len, msglevel);
+        }
+        else if (streq(p[1], "NTP") && p[2])
+        {
+            dhcp_option_address_parse("NTP", p[2], o->ntp, &o->ntp_len, msglevel);
+        }
+        else if (streq(p[1], "NBDD") && p[2])
+        {
+            dhcp_option_address_parse("NBDD", p[2], o->nbdd, &o->nbdd_len, msglevel);
+        }
+        else if (streq(p[1], "DISABLE-NBT") && !p[2])
+        {
+            o->disable_nbt = 1;
+        }
+        else
+        {
+            msg(msglevel, "--dhcp-option: unknown option type '%s' or missing or unknown parameter", p[1]);
+            goto err;
+        }
+
+        /* flag that we have options to give to the TAP driver's DHCPv4 server
+         *  - skipped for "DNS6", as that's not a DHCPv4 option
+         */
+        if (!ipv6dns)
+        {
+            o->dhcp_options = true;
+        }
+    }
+#endif /* if defined(_WIN32) || defined(TARGET_ANDROID) */
+#ifdef _WIN32
+    else if (streq(p[0], "show-adapters") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        show_tap_win_adapters(M_INFO|M_NOPREFIX, M_WARN|M_NOPREFIX);
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "show-net") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        show_routes(M_INFO|M_NOPREFIX);
+        show_adapters(M_INFO|M_NOPREFIX);
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "show-net-up") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_UP);
+        options->show_net_up = true;
+    }
+    else if (streq(p[0], "tap-sleep") && p[1] && !p[2])
+    {
+        int s;
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        s = atoi(p[1]);
+        if (s < 0 || s >= 256)
+        {
+            msg(msglevel, "--tap-sleep parameter must be between 0 and 255");
+            goto err;
+        }
+        options->tuntap_options.tap_sleep = s;
+    }
+    else if (streq(p[0], "dhcp-renew") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        options->tuntap_options.dhcp_renew = true;
+    }
+    else if (streq(p[0], "dhcp-pre-release") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        options->tuntap_options.dhcp_pre_release = true;
+        options->tuntap_options.dhcp_renew = true;
+    }
+    else if (streq(p[0], "dhcp-release") && !p[1])
+    {
+        msg(M_WARN, "Obsolete option --dhcp-release detected. This is now on by default");
+    }
+    else if (streq(p[0], "dhcp-internal") && p[1] && !p[2]) /* standalone method for internal use */
+    {
+        unsigned int adapter_index;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        set_debug_level(options->verbosity, SDL_CONSTRAIN);
+        adapter_index = atou(p[1]);
+        sleep(options->tuntap_options.tap_sleep);
+        if (options->tuntap_options.dhcp_pre_release)
+        {
+            dhcp_release_by_adapter_index(adapter_index);
+        }
+        if (options->tuntap_options.dhcp_renew)
+        {
+            dhcp_renew_by_adapter_index(adapter_index);
+        }
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "register-dns") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        options->tuntap_options.register_dns = true;
+    }
+    else if (streq(p[0], "block-outside-dns") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        options->block_outside_dns = true;
+    }
+    else if (streq(p[0], "rdns-internal") && !p[1])
+    /* standalone method for internal use
+     *
+     * (if --register-dns is set, openvpn needs to call itself in a
+     *  sub-process to execute the required functions in a non-blocking
+     *  way, and uses --rdns-internal to signal that to itself)
+     */
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        set_debug_level(options->verbosity, SDL_CONSTRAIN);
+        if (options->tuntap_options.register_dns)
+        {
+            ipconfig_register_dns(NULL);
+        }
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "show-valid-subnets") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        show_valid_win32_tun_subnets();
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "pause-exit") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        set_pause_exit_win32();
+    }
+    else if (streq(p[0], "service") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->exit_event_name = p[1];
+        if (p[2])
+        {
+            options->exit_event_initial_state = (atoi(p[2]) != 0);
+        }
+    }
+    else if (streq(p[0], "allow-nonadmin") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        tap_allow_nonadmin_access(p[1]);
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "user") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        msg(M_WARN, "NOTE: --user option is not implemented on Windows");
+    }
+    else if (streq(p[0], "group") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        msg(M_WARN, "NOTE: --group option is not implemented on Windows");
+    }
+#else  /* ifdef _WIN32 */
+    else if (streq(p[0], "user") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->username = p[1];
+    }
+    else if (streq(p[0], "group") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->groupname = p[1];
+    }
+    else if (streq(p[0], "dhcp-option") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_IPWIN32);
+        foreign_option(options, p, 3, es);
+    }
+    else if (streq(p[0], "route-method") && p[1] && !p[2]) /* ignore when pushed to non-Windows OS */
+    {
+        VERIFY_PERMISSION(OPT_P_ROUTE_EXTRAS);
+    }
+#endif /* ifdef _WIN32 */
+#if PASSTOS_CAPABILITY
+    else if (streq(p[0], "passtos") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->passtos = true;
+    }
+#endif
+#if defined(USE_COMP)
+    else if (streq(p[0], "comp-lzo") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_COMP);
+
+#if defined(ENABLE_LZO)
+        if (p[1] && streq(p[1], "no"))
+#endif
+        {
+            options->comp.alg = COMP_ALG_STUB;
+            options->comp.flags = 0;
+        }
+#if defined(ENABLE_LZO)
+        else if (p[1])
+        {
+            if (streq(p[1], "yes"))
+            {
+                options->comp.alg = COMP_ALG_LZO;
+                options->comp.flags = 0;
+            }
+            else if (streq(p[1], "adaptive"))
+            {
+                options->comp.alg = COMP_ALG_LZO;
+                options->comp.flags = COMP_F_ADAPTIVE;
+            }
+            else
+            {
+                msg(msglevel, "bad comp-lzo option: %s -- must be 'yes', 'no', or 'adaptive'", p[1]);
+                goto err;
+            }
+        }
+        else
+        {
+            options->comp.alg = COMP_ALG_LZO;
+            options->comp.flags = COMP_F_ADAPTIVE;
+        }
+#endif /* if defined(ENABLE_LZO) */
+    }
+    else if (streq(p[0], "comp-noadapt") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_COMP);
+        options->comp.flags &= ~COMP_F_ADAPTIVE;
+    }
+    else if (streq(p[0], "compress") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_COMP);
+        if (p[1])
+        {
+            if (streq(p[1], "stub"))
+            {
+                options->comp.alg = COMP_ALG_STUB;
+                options->comp.flags = (COMP_F_SWAP|COMP_F_ADVERTISE_STUBS_ONLY);
+            }
+            else if (streq(p[1], "stub-v2"))
+            {
+                options->comp.alg = COMP_ALGV2_UNCOMPRESSED;
+                options->comp.flags = COMP_F_ADVERTISE_STUBS_ONLY;
+            }
+#if defined(ENABLE_LZO)
+            else if (streq(p[1], "lzo"))
+            {
+                options->comp.alg = COMP_ALG_LZO;
+                options->comp.flags = 0;
+            }
+#endif
+#if defined(ENABLE_LZ4)
+            else if (streq(p[1], "lz4"))
+            {
+                options->comp.alg = COMP_ALG_LZ4;
+                options->comp.flags = COMP_F_SWAP;
+            }
+            else if (streq(p[1], "lz4-v2"))
+            {
+                options->comp.alg = COMP_ALGV2_LZ4;
+                options->comp.flags = 0;
+            }
+#endif
+            else
+            {
+                msg(msglevel, "bad comp option: %s", p[1]);
+                goto err;
+            }
+        }
+        else
+        {
+            options->comp.alg = COMP_ALG_STUB;
+            options->comp.flags = COMP_F_SWAP;
+        }
+    }
+#endif /* USE_COMP */
+#ifdef ENABLE_CRYPTO
+    else if (streq(p[0], "show-ciphers") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->show_ciphers = true;
+    }
+    else if (streq(p[0], "show-digests") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->show_digests = true;
+    }
+    else if (streq(p[0], "show-engines") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->show_engines = true;
+    }
+    else if (streq(p[0], "key-direction") && p[1] && !p[2])
+    {
+        int key_direction;
+
+        key_direction = ascii2keydirection(msglevel, p[1]);
+        if (key_direction >= 0)
+        {
+            options->key_direction = key_direction;
+        }
+        else
+        {
+            goto err;
+        }
+    }
+    else if (streq(p[0], "secret") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->shared_secret_file_inline = p[2];
+        }
+        else if (p[2])
+        {
+            int key_direction;
+
+            key_direction = ascii2keydirection(msglevel, p[2]);
+            if (key_direction >= 0)
+            {
+                options->key_direction = key_direction;
+            }
+            else
+            {
+                goto err;
+            }
+        }
+        options->shared_secret_file = p[1];
+    }
+    else if (streq(p[0], "genkey") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->genkey = true;
+    }
+    else if (streq(p[0], "auth") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->authname = p[1];
+    }
+    else if (streq(p[0], "cipher") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_NCP);
+        options->ciphername = p[1];
+    }
+    else if (streq(p[0], "ncp-ciphers") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_INSTANCE);
+        options->ncp_ciphers = p[1];
+    }
+    else if (streq(p[0], "ncp-disable") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL|OPT_P_INSTANCE);
+        options->ncp_enabled = false;
+    }
+    else if (streq(p[0], "prng") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "none"))
+        {
+            options->prng_hash = NULL;
+        }
+        else
+        {
+            options->prng_hash = p[1];
+        }
+        if (p[2])
+        {
+            const int sl = atoi(p[2]);
+            if (sl >= NONCE_SECRET_LEN_MIN && sl <= NONCE_SECRET_LEN_MAX)
+            {
+                options->prng_nonce_secret_len = sl;
+            }
+            else
+            {
+                msg(msglevel, "prng parameter nonce_secret_len must be between %d and %d",
+                    NONCE_SECRET_LEN_MIN, NONCE_SECRET_LEN_MAX);
+                goto err;
+            }
+        }
+    }
+    else if (streq(p[0], "no-replay") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->replay = false;
+    }
+    else if (streq(p[0], "replay-window") && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[1])
+        {
+            int replay_window;
+
+            replay_window = atoi(p[1]);
+            if (!(MIN_SEQ_BACKTRACK <= replay_window && replay_window <= MAX_SEQ_BACKTRACK))
+            {
+                msg(msglevel, "replay-window window size parameter (%d) must be between %d and %d",
+                    replay_window,
+                    MIN_SEQ_BACKTRACK,
+                    MAX_SEQ_BACKTRACK);
+                goto err;
+            }
+            options->replay_window = replay_window;
+
+            if (p[2])
+            {
+                int replay_time;
+
+                replay_time = atoi(p[2]);
+                if (!(MIN_TIME_BACKTRACK <= replay_time && replay_time <= MAX_TIME_BACKTRACK))
+                {
+                    msg(msglevel, "replay-window time window parameter (%d) must be between %d and %d",
+                        replay_time,
+                        MIN_TIME_BACKTRACK,
+                        MAX_TIME_BACKTRACK);
+                    goto err;
+                }
+                options->replay_time = replay_time;
+            }
+        }
+        else
+        {
+            msg(msglevel, "replay-window option is missing window size parameter");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "mute-replay-warnings") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->mute_replay_warnings = true;
+    }
+    else if (streq(p[0], "no-iv") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->use_iv = false;
+    }
+    else if (streq(p[0], "replay-persist") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->packet_id_file = p[1];
+    }
+    else if (streq(p[0], "test-crypto") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->test_crypto = true;
+    }
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    else if (streq(p[0], "engine") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[1])
+        {
+            options->engine = p[1];
+        }
+        else
+        {
+            options->engine = "auto";
+        }
+    }
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+#ifdef HAVE_EVP_CIPHER_CTX_SET_KEY_LENGTH
+    else if (streq(p[0], "keysize") && p[1] && !p[2])
+    {
+        int keysize;
+
+        VERIFY_PERMISSION(OPT_P_NCP);
+        keysize = atoi(p[1]) / 8;
+        if (keysize < 0 || keysize > MAX_CIPHER_KEY_LENGTH)
+        {
+            msg(msglevel, "Bad keysize: %s", p[1]);
+            goto err;
+        }
+        options->keysize = keysize;
+    }
+#endif
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    else if (streq(p[0], "use-prediction-resistance") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->use_prediction_resistance = true;
+    }
+#endif
+    else if (streq(p[0], "show-tls") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->show_tls_ciphers = true;
+    }
+    else if (streq(p[0], "show-curves") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->show_curves = true;
+    }
+    else if (streq(p[0], "ecdh-curve") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ecdh_curve = p[1];
+    }
+    else if (streq(p[0], "tls-server") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tls_server = true;
+    }
+    else if (streq(p[0], "tls-client") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tls_client = true;
+    }
+    else if (streq(p[0], "ca") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ca_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->ca_file_inline = p[2];
+        }
+    }
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    else if (streq(p[0], "capath") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->ca_path = p[1];
+    }
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+    else if (streq(p[0], "dh") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->dh_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->dh_file_inline = p[2];
+        }
+    }
+    else if (streq(p[0], "cert") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->cert_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->cert_file_inline = p[2];
+        }
+    }
+    else if (streq(p[0], "extra-certs") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->extra_certs_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->extra_certs_file_inline = p[2];
+        }
+    }
+    else if (streq(p[0], "verify-hash") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        if (!p[2] || (p[2] && streq(p[2], "SHA1")))
+        {
+            options->verify_hash = parse_hash_fingerprint(p[1], SHA_DIGEST_LENGTH, msglevel, &options->gc);
+            options->verify_hash_algo = MD_SHA1;
+        }
+        else if (p[2] && streq(p[2], "SHA256"))
+        {
+            options->verify_hash = parse_hash_fingerprint(p[1], SHA256_DIGEST_LENGTH, msglevel, &options->gc);
+            options->verify_hash_algo = MD_SHA256;
+        }
+        else
+        {
+            msg(msglevel, "invalid or unsupported hashing algorithm: %s  (only SHA1 and SHA256 are valid)", p[2]);
+            goto err;
+        }
+    }
+#ifdef ENABLE_CRYPTOAPI
+    else if (streq(p[0], "cryptoapicert") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->cryptoapi_cert = p[1];
+    }
+#endif
+    else if (streq(p[0], "key") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->priv_key_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->priv_key_file_inline = p[2];
+        }
+    }
+    else if (streq(p[0], "tls-version-min") && p[1] && !p[3])
+    {
+        int ver;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ver = tls_version_parse(p[1], p[2]);
+        if (ver == TLS_VER_BAD)
+        {
+            msg(msglevel, "unknown tls-version-min parameter: %s", p[1]);
+            goto err;
+        }
+        options->ssl_flags &=
+            ~(SSLF_TLS_VERSION_MIN_MASK << SSLF_TLS_VERSION_MIN_SHIFT);
+        options->ssl_flags |= (ver << SSLF_TLS_VERSION_MIN_SHIFT);
+    }
+    else if (streq(p[0], "tls-version-max") && p[1] && !p[2])
+    {
+        int ver;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ver = tls_version_parse(p[1], NULL);
+        if (ver == TLS_VER_BAD)
+        {
+            msg(msglevel, "unknown tls-version-max parameter: %s", p[1]);
+            goto err;
+        }
+        options->ssl_flags &=
+            ~(SSLF_TLS_VERSION_MAX_MASK << SSLF_TLS_VERSION_MAX_SHIFT);
+        options->ssl_flags |= (ver << SSLF_TLS_VERSION_MAX_SHIFT);
+    }
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    else if (streq(p[0], "pkcs12") && p[1] && ((streq(p[1], INLINE_FILE_TAG) && p[2]) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->pkcs12_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->pkcs12_file_inline = p[2];
+        }
+    }
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+    else if (streq(p[0], "askpass") && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[1])
+        {
+            options->key_pass_file = p[1];
+        }
+        else
+        {
+            options->key_pass_file = "stdin";
+        }
+    }
+    else if (streq(p[0], "auth-nocache") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        ssl_set_auth_nocache();
+    }
+    else if (streq(p[0], "auth-token") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_ECHO);
+        ssl_set_auth_token(p[1]);
+#ifdef ENABLE_MANAGEMENT
+        if (management)
+        {
+            management_auth_token(management, p[1]);
+        }
+#endif
+    }
+    else if (streq(p[0], "single-session") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->single_session = true;
+    }
+#ifdef ENABLE_PUSH_PEER_INFO
+    else if (streq(p[0], "push-peer-info") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->push_peer_info = true;
+    }
+#endif
+    else if (streq(p[0], "tls-exit") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tls_exit = true;
+    }
+    else if (streq(p[0], "tls-cipher") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->cipher_list = p[1];
+    }
+    else if (streq(p[0], "tls-cert-profile") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tls_cert_profile = p[1];
+    }
+    else if (streq(p[0], "tls-ciphersuites") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->cipher_list_tls13 = p[1];
+    }
+    else if (streq(p[0], "crl-verify") && p[1] && ((p[2] && streq(p[2], "dir"))
+                                                   || (p[2] && streq(p[1], INLINE_FILE_TAG) ) || !p[2]) && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (p[2] && streq(p[2], "dir"))
+        {
+            options->ssl_flags |= SSLF_CRL_VERIFY_DIR;
+        }
+        options->crl_file = p[1];
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->crl_file_inline = p[2];
+        }
+    }
+    else if (streq(p[0], "tls-verify") && p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_SCRIPT);
+        if (!no_more_than_n_args(msglevel, p, 2, NM_QUOTE_HINT))
+        {
+            goto err;
+        }
+        set_user_script(options, &options->tls_verify,
+                        string_substitute(p[1], ',', ' ', &options->gc),
+                        "tls-verify", true);
+    }
+#ifndef ENABLE_CRYPTO_MBEDTLS
+    else if (streq(p[0], "tls-export-cert") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->tls_export_cert = p[1];
+    }
+#endif
+#if P2MP_SERVER
+    else if (streq(p[0], "compat-names") && ((p[1] && streq(p[1], "no-remapping")) || !p[1]) && !p[2])
+#else
+    else if (streq(p[0], "compat-names") && !p[1])
+#endif
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (options->verify_x509_type != VERIFY_X509_NONE)
+        {
+            msg(msglevel, "you cannot use --compat-names with --verify-x509-name");
+            goto err;
+        }
+        msg(M_WARN, "DEPRECATED OPTION: --compat-names, please update your configuration. This will be removed in OpenVPN 2.5.");
+        compat_flag(COMPAT_FLAG_SET | COMPAT_NAMES);
+#if P2MP_SERVER
+        if (p[1] && streq(p[1], "no-remapping"))
+        {
+            compat_flag(COMPAT_FLAG_SET | COMPAT_NO_NAME_REMAPPING);
+        }
+    }
+    else if (streq(p[0], "no-name-remapping") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (options->verify_x509_type != VERIFY_X509_NONE)
+        {
+            msg(msglevel, "you cannot use --no-name-remapping with --verify-x509-name");
+            goto err;
+        }
+        msg(M_WARN, "DEPRECATED OPTION: --no-name-remapping, please update your configuration. This will be removed in OpenVPN 2.5.");
+        compat_flag(COMPAT_FLAG_SET | COMPAT_NAMES);
+        compat_flag(COMPAT_FLAG_SET | COMPAT_NO_NAME_REMAPPING);
+#endif
+    }
+    else if (streq(p[0], "verify-x509-name") && p[1] && strlen(p[1]) && !p[3])
+    {
+        int type = VERIFY_X509_SUBJECT_DN;
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NAMES))
+        {
+            msg(msglevel, "you cannot use --verify-x509-name with "
+                "--compat-names or --no-name-remapping");
+            goto err;
+        }
+        if (p[2])
+        {
+            if (streq(p[2], "subject"))
+            {
+                type = VERIFY_X509_SUBJECT_DN;
+            }
+            else if (streq(p[2], "name"))
+            {
+                type = VERIFY_X509_SUBJECT_RDN;
+            }
+            else if (streq(p[2], "name-prefix"))
+            {
+                type = VERIFY_X509_SUBJECT_RDN_PREFIX;
+            }
+            else
+            {
+                msg(msglevel, "unknown X.509 name type: %s", p[2]);
+                goto err;
+            }
+        }
+        options->verify_x509_type = type;
+        options->verify_x509_name = p[1];
+    }
+    else if (streq(p[0], "ns-cert-type") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], "server"))
+        {
+            options->ns_cert_type = NS_CERT_CHECK_SERVER;
+        }
+        else if (streq(p[1], "client"))
+        {
+            options->ns_cert_type = NS_CERT_CHECK_CLIENT;
+        }
+        else
+        {
+            msg(msglevel, "--ns-cert-type must be 'client' or 'server'");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "remote-cert-ku"))
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        size_t j;
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            sscanf(p[j], "%x", &(options->remote_cert_ku[j-1]));
+        }
+        if (j == 1)
+        {
+            /* No specific KU required, but require KU to be present */
+            options->remote_cert_ku[0] = OPENVPN_KU_REQUIRED;
+        }
+    }
+    else if (streq(p[0], "remote-cert-eku") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->remote_cert_eku = p[1];
+    }
+    else if (streq(p[0], "remote-cert-tls") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        if (streq(p[1], "server"))
+        {
+            options->remote_cert_ku[0] = OPENVPN_KU_REQUIRED;
+            options->remote_cert_eku = "TLS Web Server Authentication";
+        }
+        else if (streq(p[1], "client"))
+        {
+            options->remote_cert_ku[0] = OPENVPN_KU_REQUIRED;
+            options->remote_cert_eku = "TLS Web Client Authentication";
+        }
+        else
+        {
+            msg(msglevel, "--remote-cert-tls must be 'client' or 'server'");
+            goto err;
+        }
+    }
+    else if (streq(p[0], "tls-timeout") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->tls_timeout = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "reneg-bytes") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->renegotiate_bytes = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "reneg-pkts") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->renegotiate_packets = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "reneg-sec") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->renegotiate_seconds = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "hand-window") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->handshake_window = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "tran-window") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_TLS_PARMS);
+        options->transition_window = positive_atoi(p[1]);
+    }
+    else if (streq(p[0], "tls-auth") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->tls_auth_file_inline = p[2];
+        }
+        else if (p[2])
+        {
+            int key_direction;
+
+            key_direction = ascii2keydirection(msglevel, p[2]);
+            if (key_direction >= 0)
+            {
+                options->key_direction = key_direction;
+            }
+            else
+            {
+                goto err;
+            }
+        }
+        options->tls_auth_file = p[1];
+    }
+    else if (streq(p[0], "tls-crypt") && p[1] && !p[3])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (streq(p[1], INLINE_FILE_TAG) && p[2])
+        {
+            options->tls_crypt_inline = p[2];
+        }
+        options->tls_crypt_file = p[1];
+    }
+    else if (streq(p[0], "key-method") && p[1] && !p[2])
+    {
+        int key_method;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        key_method = atoi(p[1]);
+        if (key_method < KEY_METHOD_MIN || key_method > KEY_METHOD_MAX)
+        {
+            msg(msglevel, "key_method parameter (%d) must be >= %d and <= %d",
+                key_method,
+                KEY_METHOD_MIN,
+                KEY_METHOD_MAX);
+            goto err;
+        }
+        options->key_method = key_method;
+    }
+    else if (streq(p[0], "x509-track") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        x509_track_add(&options->x509_track, p[1], msglevel, &options->gc);
+    }
+#ifdef ENABLE_X509ALTUSERNAME
+    else if (streq(p[0], "x509-username-field") && p[1] && !p[2])
+    {
+        /* This option used to automatically upcase the fieldname passed as the
+         * option argument, e.g., "ou" became "OU". Now, this "helpfulness" is
+         * fine-tuned by only upcasing Subject field attribute names which consist
+         * of all lower-case characters. Mixed-case attributes such as
+         * "emailAddress" are left as-is. An option parameter having the "ext:"
+         * prefix for matching X.509v3 extended fields will also remain unchanged.
+         */
+        char *s = p[1];
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        if (strncmp("ext:", s, 4) != 0)
+        {
+            size_t i = 0;
+            while (s[i] && !isupper(s[i]))
+            {
+                i++;
+            }
+            if (strlen(s) == i)
+            {
+                while ((*s = toupper(*s)) != '\0')
+                {
+                    s++;
+                }
+                msg(M_WARN, "DEPRECATED FEATURE: automatically upcased the "
+                    "--x509-username-field parameter to '%s'; please update your"
+                    "configuration", p[1]);
+            }
+        }
+        else if (!x509_username_field_ext_supported(s+4))
+        {
+            msg(msglevel, "Unsupported x509-username-field extension: %s", s);
+        }
+        options->x509_username_field = p[1];
+    }
+#endif /* ENABLE_X509ALTUSERNAME */
+#endif /* ENABLE_CRYPTO */
+#ifdef ENABLE_PKCS11
+    else if (streq(p[0], "show-pkcs11-ids") && !p[3])
+    {
+        char *provider =  p[1];
+        bool cert_private = (p[2] == NULL ? false : ( atoi(p[2]) != 0 ));
+
+#ifdef DEFAULT_PKCS11_MODULE
+        if (!provider)
+        {
+            provider = DEFAULT_PKCS11_MODULE;
+        }
+        else if (!p[2])
+        {
+            char *endp = NULL;
+            int i = strtol(provider, &endp, 10);
+
+            if (*endp == 0)
+            {
+                /* There was one argument, and it was purely numeric.
+                 * Interpret it as the cert_private argument */
+                provider = DEFAULT_PKCS11_MODULE;
+                cert_private = i;
+            }
+        }
+#else  /* ifdef DEFAULT_PKCS11_MODULE */
+        if (!provider)
+        {
+            msg(msglevel, "--show-pkcs11-ids requires a provider parameter");
+            goto err;
+        }
+#endif /* ifdef DEFAULT_PKCS11_MODULE */
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        set_debug_level(options->verbosity, SDL_CONSTRAIN);
+        show_pkcs11_ids(provider, cert_private);
+        openvpn_exit(OPENVPN_EXIT_STATUS_GOOD); /* exit point */
+    }
+    else if (streq(p[0], "pkcs11-providers") && p[1])
+    {
+        int j;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            options->pkcs11_providers[j-1] = p[j];
+        }
+    }
+    else if (streq(p[0], "pkcs11-protected-authentication"))
+    {
+        int j;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            options->pkcs11_protected_authentication[j-1] = atoi(p[j]) != 0 ? 1 : 0;
+        }
+    }
+    else if (streq(p[0], "pkcs11-private-mode") && p[1])
+    {
+        int j;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            sscanf(p[j], "%x", &(options->pkcs11_private_mode[j-1]));
+        }
+    }
+    else if (streq(p[0], "pkcs11-cert-private"))
+    {
+        int j;
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        for (j = 1; j < MAX_PARMS && p[j] != NULL; ++j)
+        {
+            options->pkcs11_cert_private[j-1] = atoi(p[j]) != 0 ? 1 : 0;
+        }
+    }
+    else if (streq(p[0], "pkcs11-pin-cache") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->pkcs11_pin_cache_period = atoi(p[1]);
+    }
+    else if (streq(p[0], "pkcs11-id") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->pkcs11_id = p[1];
+    }
+    else if (streq(p[0], "pkcs11-id-management") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->pkcs11_id_management = true;
+    }
+#endif /* ifdef ENABLE_PKCS11 */
+    else if (streq(p[0], "rmtun") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->persist_config = true;
+        options->persist_mode = 0;
+    }
+    else if (streq(p[0], "mktun") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->persist_config = true;
+        options->persist_mode = 1;
+    }
+    else if (streq(p[0], "peer-id") && p[1] && !p[2])
+    {
+        VERIFY_PERMISSION(OPT_P_PEER_ID);
+        options->use_peer_id = true;
+        options->peer_id = atoi(p[1]);
+    }
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10001000
+    else if (streq(p[0], "keying-material-exporter") && p[1] && p[2])
+    {
+        int ekm_length = positive_atoi(p[2]);
+
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+
+        if (strncmp(p[1], "EXPORTER", 8))
+        {
+            msg(msglevel, "Keying material exporter label must begin with "
+                "\"EXPORTER\"");
+            goto err;
+        }
+        if (ekm_length < 16 || ekm_length > 4095)
+        {
+            msg(msglevel, "Invalid keying material exporter length");
+            goto err;
+        }
+
+        options->keying_material_exporter_label = p[1];
+        options->keying_material_exporter_length = ekm_length;
+    }
+#endif /* if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10001000 */
+    else if (streq(p[0], "allow-recursive-routing") && !p[1])
+    {
+        VERIFY_PERMISSION(OPT_P_GENERAL);
+        options->allow_recursive_routing = true;
+    }
+    else
+    {
+        int i;
+        int msglevel = msglevel_fc;
+        /* Check if an option is in --ignore-unknown-option and
+         * set warning level to non fatal */
+        for (i = 0; options->ignore_unknown_option && options->ignore_unknown_option[i]; i++)
+        {
+            if (streq(p[0], options->ignore_unknown_option[i]))
+            {
+                msglevel = M_WARN;
+                break;
+            }
+        }
+        if (file)
+        {
+            msg(msglevel, "Unrecognized option or missing or extra parameter(s) in %s:%d: %s (%s)", file, line, p[0], PACKAGE_VERSION);
+        }
+        else
+        {
+            msg(msglevel, "Unrecognized option or missing or extra parameter(s): --%s (%s)", p[0], PACKAGE_VERSION);
+        }
+    }
+err:
+    gc_free(&gc);
+}
diff --git a/src/openvpn/options.h b/src/openvpn/options.h
new file mode 100644
index 0000000..f3cafea
--- /dev/null
+++ b/src/openvpn/options.h
@@ -0,0 +1,821 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * 2004-01-28: Added Socks5 proxy support
+ *   (Christof Meerwald, http://cmeerw.org)
+ */
+
+#ifndef OPTIONS_H
+#define OPTIONS_H
+
+#include "basic.h"
+#include "common.h"
+#include "mtu.h"
+#include "route.h"
+#include "tun.h"
+#include "socket.h"
+#include "plugin.h"
+#include "manage.h"
+#include "proxy.h"
+#include "comp.h"
+#include "pushlist.h"
+#include "clinat.h"
+#ifdef ENABLE_CRYPTO
+#include "crypto_backend.h"
+#endif
+
+
+/*
+ * Maximum number of parameters associated with an option,
+ * including the option name itself.
+ */
+#define MAX_PARMS 16
+
+/*
+ * Max size of options line and parameter.
+ */
+#define OPTION_PARM_SIZE 256
+#define OPTION_LINE_SIZE 256
+
+extern const char title_string[];
+
+#if P2MP
+
+/* certain options are saved before --pull modifications are applied */
+struct options_pre_pull
+{
+    bool tuntap_options_defined;
+    struct tuntap_options tuntap_options;
+
+    bool routes_defined;
+    struct route_option_list *routes;
+
+    bool routes_ipv6_defined;
+    struct route_ipv6_option_list *routes_ipv6;
+
+    bool client_nat_defined;
+    struct client_nat_option_list *client_nat;
+
+    int foreign_option_index;
+};
+
+#endif
+#if defined(ENABLE_CRYPTO) && !defined(ENABLE_CRYPTO_OPENSSL) && !defined(ENABLE_CRYPTO_MBEDTLS)
+#error "At least one of OpenSSL or mbed TLS needs to be defined."
+#endif
+
+struct connection_entry
+{
+    int proto;
+    sa_family_t af;
+    const char *local_port;
+    bool local_port_defined;
+    const char *remote_port;
+    const char *local;
+    const char *remote;
+    bool remote_float;
+    bool bind_defined;
+    bool bind_ipv6_only;
+    bool bind_local;
+    int connect_retry_seconds;
+    int connect_retry_seconds_max;
+    int connect_timeout;
+    struct http_proxy_options *http_proxy_options;
+    const char *socks_proxy_server;
+    const char *socks_proxy_port;
+    const char *socks_proxy_authfile;
+
+    int tun_mtu;         /* MTU of tun device */
+    bool tun_mtu_defined; /* true if user overriding parm with command line option */
+    int tun_mtu_extra;
+    bool tun_mtu_extra_defined;
+    int link_mtu;        /* MTU of device over which tunnel packets pass via TCP/UDP */
+    bool link_mtu_defined; /* true if user overriding parm with command line option */
+
+    /* Advanced MTU negotiation and datagram fragmentation options */
+    int mtu_discover_type; /* used if OS supports setting Path MTU discovery options on socket */
+
+    int fragment;        /* internal fragmentation size */
+    int mssfix;          /* Upper bound on TCP MSS */
+    bool mssfix_default; /* true if --mssfix was supplied without a parameter */
+
+    int explicit_exit_notification; /* Explicitly tell peer when we are exiting via OCC_EXIT or [RESTART] message */
+
+#define CE_DISABLED (1<<0)
+#define CE_MAN_QUERY_PROXY (1<<1)
+#define CE_MAN_QUERY_REMOTE_UNDEF  0
+#define CE_MAN_QUERY_REMOTE_QUERY  1
+#define CE_MAN_QUERY_REMOTE_ACCEPT 2
+#define CE_MAN_QUERY_REMOTE_MOD    3
+#define CE_MAN_QUERY_REMOTE_SKIP   4
+#define CE_MAN_QUERY_REMOTE_MASK   (0x07)
+#define CE_MAN_QUERY_REMOTE_SHIFT  (2)
+    unsigned int flags;
+};
+
+struct remote_entry
+{
+    const char *remote;
+    const char *remote_port;
+    int proto;
+    sa_family_t af;
+};
+
+#define CONNECTION_LIST_SIZE 64
+
+struct connection_list
+{
+    int len;
+    int current;
+    struct connection_entry *array[CONNECTION_LIST_SIZE];
+};
+
+struct remote_list
+{
+    int len;
+    struct remote_entry *array[CONNECTION_LIST_SIZE];
+};
+
+struct remote_host_store
+{
+#define RH_HOST_LEN 80
+    char host[RH_HOST_LEN];
+#define RH_PORT_LEN 20
+    char port[RH_PORT_LEN];
+};
+
+/* Command line options */
+struct options
+{
+    struct gc_arena gc;
+    bool gc_owned;
+
+    /* first config file */
+    const char *config;
+
+    /* major mode */
+#define MODE_POINT_TO_POINT 0
+#define MODE_SERVER         1
+    int mode;
+
+    /* enable forward compatibility for post-2.1 features */
+    bool forward_compatible;
+    /* list of options that should be ignored even if unknown */
+    const char **ignore_unknown_option;
+
+    /* persist parms */
+    bool persist_config;
+    int persist_mode;
+
+#ifdef ENABLE_CRYPTO
+    const char *key_pass_file;
+    bool show_ciphers;
+    bool show_digests;
+    bool show_engines;
+    bool show_tls_ciphers;
+    bool show_curves;
+    bool genkey;
+#endif
+
+    /* Networking parms */
+    int connect_retry_max;
+    struct connection_entry ce;
+    struct connection_list *connection_list;
+
+    struct remote_list *remote_list;
+    /* Do not advanced the connection or remote addr list*/
+    bool no_advance;
+    /* Counts the number of unsuccessful connection attempts */
+    unsigned int unsuccessful_attempts;
+
+#if ENABLE_MANAGEMENT
+    struct http_proxy_options *http_proxy_override;
+#endif
+
+    struct remote_host_store *rh_store;
+
+    bool remote_random;
+    const char *ipchange;
+    const char *dev;
+    const char *dev_type;
+    const char *dev_node;
+    const char *lladdr;
+    int topology; /* one of the TOP_x values from proto.h */
+    const char *ifconfig_local;
+    const char *ifconfig_remote_netmask;
+    const char *ifconfig_ipv6_local;
+    int ifconfig_ipv6_netbits;
+    const char *ifconfig_ipv6_remote;
+    bool ifconfig_noexec;
+    bool ifconfig_nowarn;
+#ifdef ENABLE_FEATURE_SHAPER
+    int shaper;
+#endif
+
+    int proto_force;
+
+#ifdef ENABLE_OCC
+    bool mtu_test;
+#endif
+
+#ifdef ENABLE_MEMSTATS
+    char *memstats_fn;
+#endif
+
+    bool mlock;
+
+    int keepalive_ping;         /* a proxy for ping/ping-restart */
+    int keepalive_timeout;
+
+    int inactivity_timeout;     /* --inactive */
+    int inactivity_minimum_bytes;
+
+    int ping_send_timeout;      /* Send a TCP/UDP ping to remote every n seconds */
+    int ping_rec_timeout;       /* Expect a TCP/UDP ping from remote at least once every n seconds */
+    bool ping_timer_remote;     /* Run ping timer only if we have a remote address */
+
+#define PING_UNDEF   0
+#define PING_EXIT    1
+#define PING_RESTART 2
+    int ping_rec_timeout_action; /* What action to take on ping_rec_timeout (exit or restart)? */
+
+    bool persist_tun;           /* Don't close/reopen TUN/TAP dev on SIGUSR1 or PING_RESTART */
+    bool persist_local_ip;      /* Don't re-resolve local address on SIGUSR1 or PING_RESTART */
+    bool persist_remote_ip;     /* Don't re-resolve remote address on SIGUSR1 or PING_RESTART */
+    bool persist_key;           /* Don't re-read key files on SIGUSR1 or PING_RESTART */
+
+#if PASSTOS_CAPABILITY
+    bool passtos;
+#endif
+
+    int resolve_retry_seconds;  /* If hostname resolve fails, retry for n seconds */
+    bool resolve_in_advance;
+    const char *ip_remote_hint;
+
+    struct tuntap_options tuntap_options;
+
+    /* Misc parms */
+    const char *username;
+    const char *groupname;
+    const char *chroot_dir;
+    const char *cd_dir;
+#ifdef ENABLE_SELINUX
+    char *selinux_context;
+#endif
+    const char *writepid;
+    const char *up_script;
+    const char *down_script;
+    bool user_script_used;
+    bool down_pre;
+    bool up_delay;
+    bool up_restart;
+    bool daemon;
+
+    int remap_sigusr1;
+
+    /* inetd modes defined in socket.h */
+    int inetd;
+
+    bool log;
+    bool suppress_timestamps;
+    bool machine_readable_output;
+    int nice;
+    int verbosity;
+    int mute;
+
+#ifdef ENABLE_DEBUG
+    int gremlin;
+#endif
+
+    const char *status_file;
+    int status_file_version;
+    int status_file_update_freq;
+
+    /* optimize TUN/TAP/UDP writes */
+    bool fast_io;
+
+#ifdef USE_COMP
+    struct compress_options comp;
+#endif
+
+    /* buffer sizes */
+    int rcvbuf;
+    int sndbuf;
+
+    /* mark value */
+    int mark;
+
+    /* socket flags */
+    unsigned int sockflags;
+
+    /* route management */
+    const char *route_script;
+    const char *route_predown_script;
+    const char *route_default_gateway;
+    int route_default_metric;
+    bool route_noexec;
+    int route_delay;
+    int route_delay_window;
+    bool route_delay_defined;
+    struct route_option_list *routes;
+    struct route_ipv6_option_list *routes_ipv6;                 /* IPv6 */
+    bool route_nopull;
+    bool route_gateway_via_dhcp;
+    bool allow_pull_fqdn; /* as a client, allow server to push a FQDN for certain parameters */
+    struct client_nat_option_list *client_nat;
+
+#ifdef ENABLE_OCC
+    /* Enable options consistency check between peers */
+    bool occ;
+#endif
+
+#ifdef ENABLE_MANAGEMENT
+    const char *management_addr;
+    const char *management_port;
+    const char *management_user_pass;
+    int management_log_history_cache;
+    int management_echo_buffer_size;
+    int management_state_buffer_size;
+    const char *management_write_peer_info_file;
+
+    const char *management_client_user;
+    const char *management_client_group;
+
+    /* Mask of MF_ values of manage.h */
+    unsigned int management_flags;
+    const char *management_certificate;
+#endif
+
+#ifdef ENABLE_PLUGIN
+    struct plugin_option_list *plugin_list;
+#endif
+
+
+
+#if P2MP
+
+#if P2MP_SERVER
+    /* the tmp dir is for now only used in the P2P server context */
+    const char *tmp_dir;
+    bool server_defined;
+    in_addr_t server_network;
+    in_addr_t server_netmask;
+    bool server_ipv6_defined;                           /* IPv6 */
+    struct in6_addr server_network_ipv6;                /* IPv6 */
+    unsigned int server_netbits_ipv6;                   /* IPv6 */
+
+#define SF_NOPOOL (1<<0)
+#define SF_TCP_NODELAY_HELPER (1<<1)
+#define SF_NO_PUSH_ROUTE_GATEWAY (1<<2)
+    unsigned int server_flags;
+
+    bool server_bridge_proxy_dhcp;
+
+    bool server_bridge_defined;
+    in_addr_t server_bridge_ip;
+    in_addr_t server_bridge_netmask;
+    in_addr_t server_bridge_pool_start;
+    in_addr_t server_bridge_pool_end;
+
+    struct push_list push_list;
+    bool ifconfig_pool_defined;
+    in_addr_t ifconfig_pool_start;
+    in_addr_t ifconfig_pool_end;
+    in_addr_t ifconfig_pool_netmask;
+    const char *ifconfig_pool_persist_filename;
+    int ifconfig_pool_persist_refresh_freq;
+
+    bool ifconfig_ipv6_pool_defined;                    /* IPv6 */
+    struct in6_addr ifconfig_ipv6_pool_base;            /* IPv6 */
+    int ifconfig_ipv6_pool_netbits;                     /* IPv6 */
+
+    int real_hash_size;
+    int virtual_hash_size;
+    const char *client_connect_script;
+    const char *client_disconnect_script;
+    const char *learn_address_script;
+    const char *client_config_dir;
+    bool ccd_exclusive;
+    bool disable;
+    int n_bcast_buf;
+    int tcp_queue_limit;
+    struct iroute *iroutes;
+    struct iroute_ipv6 *iroutes_ipv6;                   /* IPv6 */
+    bool push_ifconfig_defined;
+    in_addr_t push_ifconfig_local;
+    in_addr_t push_ifconfig_remote_netmask;
+    in_addr_t push_ifconfig_local_alias;
+    bool push_ifconfig_constraint_defined;
+    in_addr_t push_ifconfig_constraint_network;
+    in_addr_t push_ifconfig_constraint_netmask;
+    bool push_ifconfig_ipv6_defined;                    /* IPv6 */
+    struct in6_addr push_ifconfig_ipv6_local;           /* IPv6 */
+    int push_ifconfig_ipv6_netbits;                     /* IPv6 */
+    struct in6_addr push_ifconfig_ipv6_remote;          /* IPv6 */
+    bool push_ifconfig_ipv6_blocked;                    /* IPv6 */
+    bool enable_c2c;
+    bool duplicate_cn;
+    int cf_max;
+    int cf_per;
+    int max_clients;
+    int max_routes_per_client;
+    int stale_routes_check_interval;
+    int stale_routes_ageing_time;
+
+    const char *auth_user_pass_verify_script;
+    bool auth_user_pass_verify_script_via_file;
+    bool auth_token_generate;
+    unsigned int auth_token_lifetime;
+#if PORT_SHARE
+    char *port_share_host;
+    char *port_share_port;
+    const char *port_share_journal_dir;
+#endif
+#endif /* if P2MP_SERVER */
+
+    bool client;
+    bool pull; /* client pull of config options from server */
+    int push_continuation;
+    unsigned int push_option_types_found;
+    const char *auth_user_pass_file;
+    struct options_pre_pull *pre_pull;
+
+    int scheduled_exit_interval;
+
+#ifdef ENABLE_CLIENT_CR
+    struct static_challenge_info sc_info;
+#endif
+#endif /* if P2MP */
+
+#ifdef ENABLE_CRYPTO
+    /* Cipher parms */
+    const char *shared_secret_file;
+    const char *shared_secret_file_inline;
+    int key_direction;
+    const char *ciphername;
+    bool ncp_enabled;
+    const char *ncp_ciphers;
+    const char *authname;
+    int keysize;
+    const char *prng_hash;
+    int prng_nonce_secret_len;
+    const char *engine;
+    bool replay;
+    bool mute_replay_warnings;
+    int replay_window;
+    int replay_time;
+    const char *packet_id_file;
+    bool use_iv;
+    bool test_crypto;
+#ifdef ENABLE_PREDICTION_RESISTANCE
+    bool use_prediction_resistance;
+#endif
+
+    /* TLS (control channel) parms */
+    bool tls_server;
+    bool tls_client;
+    const char *ca_file;
+    const char *ca_path;
+    const char *dh_file;
+    const char *cert_file;
+    const char *extra_certs_file;
+    const char *priv_key_file;
+    const char *pkcs12_file;
+    const char *cipher_list;
+    const char *cipher_list_tls13;
+    const char *tls_cert_profile;
+    const char *ecdh_curve;
+    const char *tls_verify;
+    int verify_x509_type;
+    const char *verify_x509_name;
+    const char *tls_export_cert;
+    const char *crl_file;
+
+    const char *ca_file_inline;
+    const char *cert_file_inline;
+    const char *extra_certs_file_inline;
+    const char *crl_file_inline;
+    char *priv_key_file_inline;
+    const char *dh_file_inline;
+    const char *pkcs12_file_inline; /* contains the base64 encoding of pkcs12 file */
+
+    int ns_cert_type; /* set to 0, NS_CERT_CHECK_SERVER, or NS_CERT_CHECK_CLIENT */
+    unsigned remote_cert_ku[MAX_PARMS];
+    const char *remote_cert_eku;
+    uint8_t *verify_hash;
+    hash_algo_type verify_hash_algo;
+    unsigned int ssl_flags; /* set to SSLF_x flags from ssl.h */
+
+#ifdef ENABLE_PKCS11
+    const char *pkcs11_providers[MAX_PARMS];
+    unsigned pkcs11_private_mode[MAX_PARMS];
+    bool pkcs11_protected_authentication[MAX_PARMS];
+    bool pkcs11_cert_private[MAX_PARMS];
+    int pkcs11_pin_cache_period;
+    const char *pkcs11_id;
+    bool pkcs11_id_management;
+#endif
+
+#ifdef ENABLE_CRYPTOAPI
+    const char *cryptoapi_cert;
+#endif
+
+    /* data channel key exchange method */
+    int key_method;
+
+    /* Per-packet timeout on control channel */
+    int tls_timeout;
+
+    /* Data channel key renegotiation parameters */
+    int renegotiate_bytes;
+    int renegotiate_packets;
+    int renegotiate_seconds;
+
+    /* Data channel key handshake must finalize
+     * within n seconds of handshake initiation. */
+    int handshake_window;
+
+#ifdef ENABLE_X509ALTUSERNAME
+    /* Field used to be the username in X509 cert. */
+    char *x509_username_field;
+#endif
+
+    /* Old key allowed to live n seconds after new key goes active */
+    int transition_window;
+
+    /* Shared secret used for TLS control channel authentication */
+    const char *tls_auth_file;
+    const char *tls_auth_file_inline;
+
+    /* Shared secret used for TLS control channel authenticated encryption */
+    const char *tls_crypt_file;
+    const char *tls_crypt_inline;
+
+    /* Allow only one session */
+    bool single_session;
+
+#ifdef ENABLE_PUSH_PEER_INFO
+    bool push_peer_info;
+#endif
+
+    bool tls_exit;
+
+#endif /* ENABLE_CRYPTO */
+
+    const struct x509_track *x509_track;
+
+    /* special state parms */
+    int foreign_option_index;
+
+#ifdef _WIN32
+    HANDLE msg_channel;
+    const char *exit_event_name;
+    bool exit_event_initial_state;
+    bool show_net_up;
+    int route_method;
+    bool block_outside_dns;
+#endif
+
+    bool use_peer_id;
+    uint32_t peer_id;
+
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER >= 0x10001000
+    /* Keying Material Exporters [RFC 5705] */
+    const char *keying_material_exporter_label;
+    int keying_material_exporter_length;
+#endif
+
+    struct pull_filter_list *pull_filter_list;
+
+    /* Useful when packets sent by openvpn itself are not subject
+     * to the routing tables that would move packets into the tunnel. */
+    bool allow_recursive_routing;
+};
+
+#define streq(x, y) (!strcmp((x), (y)))
+
+/*
+ * Option classes.
+ */
+#define OPT_P_GENERAL         (1<<0)
+#define OPT_P_UP              (1<<1)
+#define OPT_P_ROUTE           (1<<2)
+#define OPT_P_IPWIN32         (1<<3)
+#define OPT_P_SCRIPT          (1<<4)
+#define OPT_P_SETENV          (1<<5)
+#define OPT_P_SHAPER          (1<<6)
+#define OPT_P_TIMER           (1<<7)
+#define OPT_P_PERSIST         (1<<8)
+#define OPT_P_PERSIST_IP      (1<<9)
+#define OPT_P_COMP            (1<<10) /* TODO */
+#define OPT_P_MESSAGES        (1<<11)
+#define OPT_P_NCP             (1<<12) /**< Negotiable crypto parameters */
+#define OPT_P_TLS_PARMS       (1<<13) /* TODO */
+#define OPT_P_MTU             (1<<14) /* TODO */
+#define OPT_P_NICE            (1<<15)
+#define OPT_P_PUSH            (1<<16)
+#define OPT_P_INSTANCE        (1<<17)
+#define OPT_P_CONFIG          (1<<18)
+#define OPT_P_EXPLICIT_NOTIFY (1<<19)
+#define OPT_P_ECHO            (1<<20)
+#define OPT_P_INHERIT         (1<<21)
+#define OPT_P_ROUTE_EXTRAS    (1<<22)
+#define OPT_P_PULL_MODE       (1<<23)
+#define OPT_P_PLUGIN          (1<<24)
+#define OPT_P_SOCKBUF         (1<<25)
+#define OPT_P_SOCKFLAGS       (1<<26)
+#define OPT_P_CONNECTION      (1<<27)
+#define OPT_P_PEER_ID         (1<<28)
+
+#define OPT_P_DEFAULT   (~(OPT_P_INSTANCE|OPT_P_PULL_MODE))
+
+#if P2MP
+#define PULL_DEFINED(opt) ((opt)->pull)
+#if P2MP_SERVER
+#define PUSH_DEFINED(opt) ((opt)->push_list)
+#endif
+#endif
+
+#ifndef PULL_DEFINED
+#define PULL_DEFINED(opt) (false)
+#endif
+
+#ifndef PUSH_DEFINED
+#define PUSH_DEFINED(opt) (false)
+#endif
+
+#ifdef _WIN32
+#define ROUTE_OPTION_FLAGS(o) ((o)->route_method & ROUTE_METHOD_MASK)
+#else
+#define ROUTE_OPTION_FLAGS(o) (0)
+#endif
+
+#ifdef ENABLE_FEATURE_SHAPER
+#define SHAPER_DEFINED(opt) ((opt)->shaper)
+#else
+#define SHAPER_DEFINED(opt) (false)
+#endif
+
+#ifdef ENABLE_PLUGIN
+#define PLUGIN_OPTION_LIST(opt) ((opt)->plugin_list)
+#else
+#define PLUGIN_OPTION_LIST(opt) (NULL)
+#endif
+
+#ifdef MANAGEMENT_DEF_AUTH
+#define MAN_CLIENT_AUTH_ENABLED(opt) ((opt)->management_flags & MF_CLIENT_AUTH)
+#else
+#define MAN_CLIENT_AUTH_ENABLED(opt) (false)
+#endif
+
+void parse_argv(struct options *options,
+                const int argc,
+                char *argv[],
+                const int msglevel,
+                const unsigned int permission_mask,
+                unsigned int *option_types_found,
+                struct env_set *es);
+
+void notnull(const char *arg, const char *description);
+
+void usage_small(void);
+
+void show_library_versions(const unsigned int flags);
+
+#ifdef _WIN32
+void show_windows_version(const unsigned int flags);
+
+#endif
+
+void init_options(struct options *o, const bool init_gc);
+
+void uninit_options(struct options *o);
+
+void setenv_settings(struct env_set *es, const struct options *o);
+
+void show_settings(const struct options *o);
+
+bool string_defined_equal(const char *s1, const char *s2);
+
+#ifdef ENABLE_OCC
+
+const char *options_string_version(const char *s, struct gc_arena *gc);
+
+char *options_string(const struct options *o,
+                     const struct frame *frame,
+                     struct tuntap *tt,
+                     bool remote,
+                     struct gc_arena *gc);
+
+bool options_cmp_equal_safe(char *actual, const char *expected, size_t actual_n);
+
+void options_warning_safe(char *actual, const char *expected, size_t actual_n);
+
+bool options_cmp_equal(char *actual, const char *expected);
+
+void options_warning(char *actual, const char *expected);
+
+#endif
+
+/**
+ * Given an OpenVPN options string, extract the value of an option.
+ *
+ * @param options_string        Zero-terminated, comma-separated options string
+ * @param opt_name              The name of the option to extract
+ * @param gc                    The gc to allocate the return value
+ *
+ * @return gc-allocated value of option with name opt_name if option was found,
+ *         or NULL otherwise.
+ */
+char *options_string_extract_option(const char *options_string,
+                                    const char *opt_name, struct gc_arena *gc);
+
+
+void options_postprocess(struct options *options);
+
+void pre_pull_save(struct options *o);
+
+void pre_pull_restore(struct options *o, struct gc_arena *gc);
+
+bool apply_push_options(struct options *options,
+                        struct buffer *buf,
+                        unsigned int permission_mask,
+                        unsigned int *option_types_found,
+                        struct env_set *es);
+
+void options_detach(struct options *o);
+
+void options_server_import(struct options *o,
+                           const char *filename,
+                           int msglevel,
+                           unsigned int permission_mask,
+                           unsigned int *option_types_found,
+                           struct env_set *es);
+
+void pre_pull_default(struct options *o);
+
+void rol_check_alloc(struct options *options);
+
+int parse_line(const char *line,
+               char *p[],
+               const int n,
+               const char *file,
+               const int line_num,
+               int msglevel,
+               struct gc_arena *gc);
+
+/*
+ * parse/print topology coding
+ */
+
+int parse_topology(const char *str, const int msglevel);
+
+const char *print_topology(const int topology);
+
+/*
+ * Manage auth-retry variable
+ */
+
+#if P2MP
+
+#define AR_NONE       0
+#define AR_INTERACT   1
+#define AR_NOINTERACT 2
+
+int auth_retry_get(void);
+
+bool auth_retry_set(const int msglevel, const char *option);
+
+const char *auth_retry_print(void);
+
+#endif
+
+void options_string_import(struct options *options,
+                           const char *config,
+                           const int msglevel,
+                           const unsigned int permission_mask,
+                           unsigned int *option_types_found,
+                           struct env_set *es);
+
+#endif /* ifndef OPTIONS_H */
diff --git a/src/openvpn/otime.c b/src/openvpn/otime.c
new file mode 100644
index 0000000..805aac9
--- /dev/null
+++ b/src/openvpn/otime.c
@@ -0,0 +1,208 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "otime.h"
+
+#include "memdbg.h"
+
+time_t now = 0;            /* GLOBAL */
+
+#if TIME_BACKTRACK_PROTECTION
+
+static time_t now_adj = 0; /* GLOBAL */
+time_t now_usec = 0;       /* GLOBAL */
+
+/*
+ * Try to filter out time instability caused by the system
+ * clock backtracking or jumping forward.
+ */
+
+void
+update_now(const time_t system_time)
+{
+    const int forward_threshold = 86400; /* threshold at which to dampen forward jumps */
+    const int backward_trigger  = 10;  /* backward jump must be >= this many seconds before we adjust */
+    time_t real_time = system_time + now_adj;
+
+    if (real_time > now)
+    {
+        const time_t overshoot = real_time - now - 1;
+        if (overshoot > forward_threshold && now_adj >= overshoot)
+        {
+            now_adj -= overshoot;
+            real_time -= overshoot;
+        }
+        now = real_time;
+    }
+    else if (real_time < now - backward_trigger)
+    {
+        now_adj += (now - real_time);
+    }
+}
+
+void
+update_now_usec(struct timeval *tv)
+{
+    const time_t last = now;
+    update_now(tv->tv_sec);
+    if (now > last || (now == last && tv->tv_usec > now_usec))
+    {
+        now_usec = tv->tv_usec;
+    }
+}
+
+#endif /* TIME_BACKTRACK_PROTECTION */
+
+/*
+ * Return a numerical string describing a struct timeval.
+ */
+const char *
+tv_string(const struct timeval *tv, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    buf_printf(&out, "[%d/%d]",
+               (int) tv->tv_sec,
+               (int )tv->tv_usec);
+    return BSTR(&out);
+}
+
+/*
+ * Return an ascii string describing an absolute
+ * date/time in a struct timeval.
+ *
+ */
+const char *
+tv_string_abs(const struct timeval *tv, struct gc_arena *gc)
+{
+    return time_string((time_t) tv->tv_sec,
+                       (int) tv->tv_usec,
+                       true,
+                       gc);
+}
+
+/* format a time_t as ascii, or use current time if 0 */
+
+const char *
+time_string(time_t t, int usec, bool show_usec, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    struct timeval tv;
+
+    if (t)
+    {
+        tv.tv_sec = t;
+        tv.tv_usec = usec;
+    }
+    else
+    {
+        gettimeofday(&tv, NULL);
+    }
+
+    t = tv.tv_sec;
+    buf_printf(&out, "%s", ctime(&t));
+    buf_rmtail(&out, '\n');
+
+    if (show_usec && tv.tv_usec)
+    {
+        buf_printf(&out, " us=%d", (int)tv.tv_usec);
+    }
+
+    return BSTR(&out);
+}
+
+/*
+ * Limit the frequency of an event stream.
+ *
+ * Used to control maximum rate of new
+ * incoming connections.
+ */
+
+struct frequency_limit *
+frequency_limit_init(int max, int per)
+{
+    struct frequency_limit *f;
+
+    ASSERT(max >= 0 && per >= 0);
+
+    ALLOC_OBJ(f, struct frequency_limit);
+    f->max = max;
+    f->per = per;
+    f->n = 0;
+    f->reset = 0;
+    return f;
+}
+
+void
+frequency_limit_free(struct frequency_limit *f)
+{
+    free(f);
+}
+
+bool
+frequency_limit_event_allowed(struct frequency_limit *f)
+{
+    if (f->per)
+    {
+        bool ret;
+        if (now >= f->reset + f->per)
+        {
+            f->reset = now;
+            f->n = 0;
+        }
+        ret = (++f->n <= f->max);
+        return ret;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+#ifdef TIME_TEST
+void
+time_test(void)
+{
+    struct timeval tv;
+    time_t t;
+    int i;
+    for (i = 0; i < 10000; ++i)
+    {
+        t = time(NULL);
+        gettimeofday(&tv, NULL);
+#if 1
+        msg(M_INFO, "t=%u s=%u us=%u",
+            (unsigned int)t,
+            (unsigned int)tv.tv_sec,
+            (unsigned int)tv.tv_usec);
+#endif
+    }
+}
+#endif
diff --git a/src/openvpn/otime.h b/src/openvpn/otime.h
new file mode 100644
index 0000000..a6f7ec2
--- /dev/null
+++ b/src/openvpn/otime.h
@@ -0,0 +1,307 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OTIME_H
+#define OTIME_H
+
+#include "common.h"
+#include "integer.h"
+#include "buffer.h"
+
+struct frequency_limit
+{
+    int max;
+    int per;
+    int n;
+    time_t reset;
+};
+
+struct frequency_limit *frequency_limit_init(int max, int per);
+
+void frequency_limit_free(struct frequency_limit *f);
+
+bool frequency_limit_event_allowed(struct frequency_limit *f);
+
+/* format a time_t as ascii, or use current time if 0 */
+const char *time_string(time_t t, int usec, bool show_usec, struct gc_arena *gc);
+
+/* struct timeval functions */
+
+const char *tv_string(const struct timeval *tv, struct gc_arena *gc);
+
+const char *tv_string_abs(const struct timeval *tv, struct gc_arena *gc);
+
+extern time_t now; /* updated frequently to time(NULL) */
+
+void time_test(void);
+
+#if TIME_BACKTRACK_PROTECTION
+
+void update_now(const time_t system_time);
+
+extern time_t now_usec;
+void update_now_usec(struct timeval *tv);
+
+static inline int
+openvpn_gettimeofday(struct timeval *tv, void *tz)
+{
+    const int status = gettimeofday(tv, tz);
+    if (!status)
+    {
+        update_now_usec(tv);
+        tv->tv_sec = now;
+        tv->tv_usec = now_usec;
+    }
+    return status;
+}
+
+static inline void
+update_time(void)
+{
+#ifdef _WIN32
+    /* on _WIN32, gettimeofday is faster than time(NULL) */
+    struct timeval tv;
+    openvpn_gettimeofday(&tv, NULL);
+#else
+    update_now(time(NULL));
+#endif
+}
+
+#else /* !TIME_BACKTRACK_PROTECTION */
+
+static inline void
+update_time(void)
+{
+#if defined(_WIN32)
+    /* on _WIN32, gettimeofday is faster than time(NULL) */
+    struct timeval tv;
+    if (!gettimeofday(&tv, NULL))
+    {
+        if (tv.tv_sec != now)
+        {
+            now = tv.tv_sec;
+        }
+    }
+#else  /* if defined(_WIN32) */
+    const time_t real_time = time(NULL);
+    if (real_time != now)
+    {
+        now = real_time;
+    }
+#endif
+}
+
+static inline int
+openvpn_gettimeofday(struct timeval *tv, void *tz)
+{
+    return gettimeofday(tv, tz);
+}
+
+#endif /* TIME_BACKTRACK_PROTECTION */
+
+static inline time_t
+openvpn_time(time_t *t)
+{
+    update_time();
+    if (t)
+    {
+        *t = now;
+    }
+    return now;
+}
+
+static inline void
+tv_clear(struct timeval *tv)
+{
+    tv->tv_sec = 0;
+    tv->tv_usec = 0;
+}
+
+static inline bool
+tv_defined(const struct timeval *tv)
+{
+    return tv->tv_sec > 0 && tv->tv_usec > 0;
+}
+
+/* return tv1 - tv2 in usec, constrained by max_seconds */
+static inline int
+tv_subtract(const struct timeval *tv1, const struct timeval *tv2, const unsigned int max_seconds)
+{
+    const int max_usec = max_seconds * 1000000;
+    const int sec_diff = tv1->tv_sec - tv2->tv_sec;
+
+    if (sec_diff > ((int)max_seconds + 10))
+    {
+        return max_usec;
+    }
+    else if (sec_diff < -((int)max_seconds + 10))
+    {
+        return -max_usec;
+    }
+    return constrain_int(sec_diff * 1000000 + (tv1->tv_usec - tv2->tv_usec), -max_usec, max_usec);
+}
+
+static inline void
+tv_add(struct timeval *dest, const struct timeval *src)
+{
+    dest->tv_sec += src->tv_sec;
+    dest->tv_usec += src->tv_usec;
+    dest->tv_sec += (dest->tv_usec >> 20);
+    dest->tv_usec &= 0x000FFFFF;
+    if (dest->tv_usec >= 1000000)
+    {
+        dest->tv_usec -= 1000000;
+        dest->tv_sec += 1;
+    }
+}
+
+static inline bool
+tv_lt(const struct timeval *t1, const struct timeval *t2)
+{
+    if (t1->tv_sec < t2->tv_sec)
+    {
+        return true;
+    }
+    else if (t1->tv_sec > t2->tv_sec)
+    {
+        return false;
+    }
+    else
+    {
+        return t1->tv_usec < t2->tv_usec;
+    }
+}
+
+static inline bool
+tv_le(const struct timeval *t1, const struct timeval *t2)
+{
+    if (t1->tv_sec < t2->tv_sec)
+    {
+        return true;
+    }
+    else if (t1->tv_sec > t2->tv_sec)
+    {
+        return false;
+    }
+    else
+    {
+        return t1->tv_usec <= t2->tv_usec;
+    }
+}
+
+static inline bool
+tv_ge(const struct timeval *t1, const struct timeval *t2)
+{
+    if (t1->tv_sec > t2->tv_sec)
+    {
+        return true;
+    }
+    else if (t1->tv_sec < t2->tv_sec)
+    {
+        return false;
+    }
+    else
+    {
+        return t1->tv_usec >= t2->tv_usec;
+    }
+}
+
+static inline bool
+tv_gt(const struct timeval *t1, const struct timeval *t2)
+{
+    if (t1->tv_sec > t2->tv_sec)
+    {
+        return true;
+    }
+    else if (t1->tv_sec < t2->tv_sec)
+    {
+        return false;
+    }
+    else
+    {
+        return t1->tv_usec > t2->tv_usec;
+    }
+}
+
+static inline bool
+tv_eq(const struct timeval *t1, const struct timeval *t2)
+{
+    return t1->tv_sec == t2->tv_sec && t1->tv_usec == t2->tv_usec;
+}
+
+static inline void
+tv_delta(struct timeval *dest, const struct timeval *t1, const struct timeval *t2)
+{
+    int sec = t2->tv_sec - t1->tv_sec;
+    int usec = t2->tv_usec - t1->tv_usec;
+
+    while (usec < 0)
+    {
+        usec += 1000000;
+        sec -= 1;
+    }
+
+    if (sec < 0)
+    {
+        usec = sec = 0;
+    }
+
+    dest->tv_sec = sec;
+    dest->tv_usec = usec;
+}
+
+#define TV_WITHIN_SIGMA_MAX_SEC 600
+#define TV_WITHIN_SIGMA_MAX_USEC (TV_WITHIN_SIGMA_MAX_SEC * 1000000)
+
+/*
+ * Is t1 and t2 within sigma microseconds of each other?
+ */
+static inline bool
+tv_within_sigma(const struct timeval *t1, const struct timeval *t2, unsigned int sigma)
+{
+    const int delta = tv_subtract(t1, t2, TV_WITHIN_SIGMA_MAX_SEC); /* sigma should be less than 10 minutes */
+    return -(int)sigma <= delta && delta <= (int)sigma;
+}
+
+/*
+ * Used to determine in how many seconds we should be
+ * called again.
+ */
+static inline void
+interval_earliest_wakeup(interval_t *wakeup, time_t at, time_t current)
+{
+    if (at > current)
+    {
+        const interval_t delta = (interval_t) (at - current);
+        if (delta < *wakeup)
+        {
+            *wakeup = delta;
+        }
+        if (*wakeup < 0)
+        {
+            *wakeup = 0;
+        }
+    }
+}
+
+#endif /* ifndef OTIME_H */
diff --git a/src/openvpn/packet_id.c b/src/openvpn/packet_id.c
new file mode 100644
index 0000000..d58761b
--- /dev/null
+++ b/src/openvpn/packet_id.c
@@ -0,0 +1,699 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * These routines are designed to catch replay attacks,
+ * where a man-in-the-middle captures packets and then
+ * attempts to replay them back later.
+ *
+ * We use the "sliding-window" algorithm, similar
+ * to IPSec.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "packet_id.h"
+#include "misc.h"
+#include "integer.h"
+
+#include "memdbg.h"
+
+/* #define PID_SIMULATE_BACKTRACK */
+
+/*
+ * Special time_t value that indicates that
+ * sequence number has expired.
+ */
+#define SEQ_UNSEEN  ((time_t)0)
+#define SEQ_EXPIRED ((time_t)1)
+
+static void packet_id_debug_print(int msglevel,
+                                  const struct packet_id_rec *p,
+                                  const struct packet_id_net *pin,
+                                  const char *message,
+                                  int value);
+
+static inline void
+packet_id_debug(int msglevel,
+                const struct packet_id_rec *p,
+                const struct packet_id_net *pin,
+                const char *message,
+                int value)
+{
+#ifdef ENABLE_DEBUG
+    if (unlikely(check_debug_level(msglevel)))
+    {
+        packet_id_debug_print(msglevel, p, pin, message, value);
+    }
+#endif
+}
+
+void
+packet_id_init(struct packet_id *p, int seq_backtrack, int time_backtrack, const char *name, int unit)
+{
+    dmsg(D_PID_DEBUG, "PID packet_id_init seq_backtrack=%d time_backtrack=%d",
+         seq_backtrack,
+         time_backtrack);
+
+    ASSERT(p);
+    CLEAR(*p);
+
+    p->rec.name = name;
+    p->rec.unit = unit;
+    if (seq_backtrack)
+    {
+        ASSERT(MIN_SEQ_BACKTRACK <= seq_backtrack && seq_backtrack <= MAX_SEQ_BACKTRACK);
+        ASSERT(MIN_TIME_BACKTRACK <= time_backtrack && time_backtrack <= MAX_TIME_BACKTRACK);
+        CIRC_LIST_ALLOC(p->rec.seq_list, struct seq_list, seq_backtrack);
+        p->rec.seq_backtrack = seq_backtrack;
+        p->rec.time_backtrack = time_backtrack;
+    }
+    p->rec.initialized = true;
+}
+
+void
+packet_id_free(struct packet_id *p)
+{
+    if (p)
+    {
+        dmsg(D_PID_DEBUG, "PID packet_id_free");
+        if (p->rec.seq_list)
+        {
+            free(p->rec.seq_list);
+        }
+        CLEAR(*p);
+    }
+}
+
+void
+packet_id_add(struct packet_id_rec *p, const struct packet_id_net *pin)
+{
+    const time_t local_now = now;
+    if (p->seq_list)
+    {
+        packet_id_type diff;
+
+        /*
+         * If time value increases, start a new
+         * sequence number sequence.
+         */
+        if (!CIRC_LIST_SIZE(p->seq_list)
+            || pin->time > p->time
+            || (pin->id >= (packet_id_type)p->seq_backtrack
+                && pin->id - (packet_id_type)p->seq_backtrack > p->id))
+        {
+            p->time = pin->time;
+            p->id = 0;
+            if (pin->id > (packet_id_type)p->seq_backtrack)
+            {
+                p->id = pin->id - (packet_id_type)p->seq_backtrack;
+            }
+            CIRC_LIST_RESET(p->seq_list);
+        }
+
+        while (p->id < pin->id
+#ifdef PID_SIMULATE_BACKTRACK
+               || (get_random() % 64) < 31
+#endif
+               )
+        {
+            CIRC_LIST_PUSH(p->seq_list, SEQ_UNSEEN);
+            ++p->id;
+        }
+
+        diff = p->id - pin->id;
+        if (diff < (packet_id_type) CIRC_LIST_SIZE(p->seq_list)
+            && local_now > SEQ_EXPIRED)
+        {
+            CIRC_LIST_ITEM(p->seq_list, diff) = local_now;
+        }
+    }
+    else
+    {
+        p->time = pin->time;
+        p->id = pin->id;
+    }
+}
+
+/*
+ * Expire sequence numbers which can no longer
+ * be accepted because they would violate
+ * time_backtrack.
+ */
+void
+packet_id_reap(struct packet_id_rec *p)
+{
+    const time_t local_now = now;
+    if (p->time_backtrack)
+    {
+        int i;
+        bool expire = false;
+        for (i = 0; i < CIRC_LIST_SIZE(p->seq_list); ++i)
+        {
+            const time_t t = CIRC_LIST_ITEM(p->seq_list, i);
+            if (t == SEQ_EXPIRED)
+            {
+                break;
+            }
+            if (!expire && t && t + p->time_backtrack < local_now)
+            {
+                expire = true;
+            }
+            if (expire)
+            {
+                CIRC_LIST_ITEM(p->seq_list, i) = SEQ_EXPIRED;
+            }
+        }
+    }
+    p->last_reap = local_now;
+}
+
+/*
+ * Return true if packet id is ok, or false if
+ * it is a replay.
+ */
+bool
+packet_id_test(struct packet_id_rec *p,
+               const struct packet_id_net *pin)
+{
+    packet_id_type diff;
+
+    packet_id_debug(D_PID_DEBUG, p, pin, "PID_TEST", 0);
+
+    ASSERT(p->initialized);
+
+    if (!pin->id)
+    {
+        return false;
+    }
+
+    if (p->seq_backtrack)
+    {
+        /*
+         * In backtrack mode, we allow packet reordering subject
+         * to the seq_backtrack and time_backtrack constraints.
+         *
+         * This mode is used with UDP.
+         */
+        if (pin->time == p->time)
+        {
+            /* is packet-id greater than any one we've seen yet? */
+            if (pin->id > p->id)
+            {
+                return true;
+            }
+
+            /* check packet-id sliding window for original/replay status */
+            diff = p->id - pin->id;
+
+            /* keep track of maximum backtrack seen for debugging purposes */
+            if ((int)diff > p->max_backtrack_stat)
+            {
+                p->max_backtrack_stat = (int)diff;
+                packet_id_debug(D_PID_DEBUG_LOW, p, pin, "PID_ERR replay-window backtrack occurred", p->max_backtrack_stat);
+            }
+
+            if (diff >= (packet_id_type) CIRC_LIST_SIZE(p->seq_list))
+            {
+                packet_id_debug(D_PID_DEBUG_LOW, p, pin, "PID_ERR large diff", diff);
+                return false;
+            }
+
+            {
+                const time_t v = CIRC_LIST_ITEM(p->seq_list, diff);
+                if (v == 0)
+                {
+                    return true;
+                }
+                else
+                {
+                    /* raised from D_PID_DEBUG_LOW to reduce verbosity */
+                    packet_id_debug(D_PID_DEBUG_MEDIUM, p, pin, "PID_ERR replay", diff);
+                    return false;
+                }
+            }
+        }
+        else if (pin->time < p->time) /* if time goes back, reject */
+        {
+            packet_id_debug(D_PID_DEBUG_LOW, p, pin, "PID_ERR time backtrack", 0);
+            return false;
+        }
+        else                        /* time moved forward */
+        {
+            return true;
+        }
+    }
+    else
+    {
+        /*
+         * In non-backtrack mode, all sequence number series must
+         * begin at some number n > 0 and must increment linearly without gaps.
+         *
+         * This mode is used with TCP.
+         */
+        if (pin->time == p->time)
+        {
+            return !p->id || pin->id == p->id + 1;
+        }
+        else if (pin->time < p->time) /* if time goes back, reject */
+        {
+            return false;
+        }
+        else                        /* time moved forward */
+        {
+            return pin->id == 1;
+        }
+    }
+}
+
+/*
+ * Read/write a packet ID to/from the buffer.  Short form is sequence number
+ * only.  Long form is sequence number and timestamp.
+ */
+
+bool
+packet_id_read(struct packet_id_net *pin, struct buffer *buf, bool long_form)
+{
+    packet_id_type net_id;
+    net_time_t net_time;
+
+    pin->id = 0;
+    pin->time = 0;
+
+    if (!buf_read(buf, &net_id, sizeof(net_id)))
+    {
+        return false;
+    }
+    pin->id = ntohpid(net_id);
+    if (long_form)
+    {
+        if (!buf_read(buf, &net_time, sizeof(net_time)))
+        {
+            return false;
+        }
+        pin->time = ntohtime(net_time);
+    }
+    return true;
+}
+
+static bool
+packet_id_send_update(struct packet_id_send *p, bool long_form)
+{
+    if (!p->time)
+    {
+        p->time = now;
+    }
+    if (p->id == PACKET_ID_MAX)
+    {
+        /* Packet ID only allowed to roll over if using long form and time has
+         * moved forward since last roll over.
+         */
+        if (!long_form || now <= p->time)
+        {
+            return false;
+        }
+        p->time = now;
+        p->id = 0;
+    }
+    p->id++;
+    return true;
+}
+
+bool
+packet_id_write(struct packet_id_send *p, struct buffer *buf, bool long_form,
+        bool prepend)
+{
+    if (!packet_id_send_update(p, long_form))
+    {
+        return false;
+    }
+
+    const packet_id_type net_id = htonpid(p->id);
+    const net_time_t net_time = htontime(p->time);
+    if (prepend)
+    {
+        if (long_form)
+        {
+            if (!buf_write_prepend(buf, &net_time, sizeof(net_time)))
+            {
+                return false;
+            }
+        }
+        if (!buf_write_prepend(buf, &net_id, sizeof(net_id)))
+        {
+            return false;
+        }
+    }
+    else
+    {
+        if (!buf_write(buf, &net_id, sizeof(net_id)))
+        {
+            return false;
+        }
+        if (long_form)
+        {
+            if (!buf_write(buf, &net_time, sizeof(net_time)))
+            {
+                return false;
+            }
+        }
+    }
+    return true;
+}
+
+const char *
+packet_id_net_print(const struct packet_id_net *pin, bool print_timestamp, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    buf_printf(&out, "[ #" packet_id_format, (packet_id_print_type)pin->id);
+    if (print_timestamp && pin->time)
+    {
+        buf_printf(&out, " / time = (" packet_id_format ") %s",
+                   (packet_id_print_type)pin->time,
+                   time_string(pin->time, 0, false, gc));
+    }
+
+    buf_printf(&out, " ]");
+    return BSTR(&out);
+}
+
+/* initialize the packet_id_persist structure in a disabled state */
+void
+packet_id_persist_init(struct packet_id_persist *p)
+{
+    p->filename = NULL;
+    p->fd = -1;
+    p->time = p->time_last_written = 0;
+    p->id = p->id_last_written = 0;
+}
+
+/* close the file descriptor if it is open, and switch to disabled state */
+void
+packet_id_persist_close(struct packet_id_persist *p)
+{
+    if (packet_id_persist_enabled(p))
+    {
+        if (close(p->fd))
+        {
+            msg(D_PID_PERSIST | M_ERRNO, "Close error on --replay-persist file %s", p->filename);
+        }
+        packet_id_persist_init(p);
+    }
+}
+
+/* load persisted rec packet_id (time and id) only once from file, and set state to enabled */
+void
+packet_id_persist_load(struct packet_id_persist *p, const char *filename)
+{
+    struct gc_arena gc = gc_new();
+    if (!packet_id_persist_enabled(p))
+    {
+        /* open packet-id persist file for both read and write */
+        p->fd = platform_open(filename,
+                              O_CREAT | O_RDWR | O_BINARY,
+                              S_IRUSR | S_IWUSR);
+        if (p->fd == -1)
+        {
+            msg(D_PID_PERSIST | M_ERRNO,
+                "Cannot open --replay-persist file %s for read/write",
+                filename);
+        }
+        else
+        {
+            struct packet_id_persist_file_image image;
+            ssize_t n;
+
+#if defined(HAVE_FLOCK) && defined(LOCK_EX) && defined(LOCK_NB)
+            if (flock(p->fd, LOCK_EX | LOCK_NB))
+            {
+                msg(M_ERR, "Cannot obtain exclusive lock on --replay-persist file %s", filename);
+            }
+#endif
+
+            p->filename = filename;
+            n = read(p->fd, &image, sizeof(image));
+            if (n == sizeof(image))
+            {
+                p->time = p->time_last_written = image.time;
+                p->id = p->id_last_written = image.id;
+                dmsg(D_PID_PERSIST_DEBUG, "PID Persist Read from %s: %s",
+                     p->filename, packet_id_persist_print(p, &gc));
+            }
+            else if (n == -1)
+            {
+                msg(D_PID_PERSIST | M_ERRNO,
+                    "Read error on --replay-persist file %s",
+                    p->filename);
+            }
+        }
+    }
+    gc_free(&gc);
+}
+
+/* save persisted rec packet_id (time and id) to file (only if enabled state) */
+void
+packet_id_persist_save(struct packet_id_persist *p)
+{
+    if (packet_id_persist_enabled(p) && p->time && (p->time != p->time_last_written
+                                                    || p->id != p->id_last_written))
+    {
+        struct packet_id_persist_file_image image;
+        ssize_t n;
+        off_t seek_ret;
+        struct gc_arena gc = gc_new();
+
+        image.time = p->time;
+        image.id = p->id;
+        seek_ret = lseek(p->fd, (off_t)0, SEEK_SET);
+        if (seek_ret == (off_t)0)
+        {
+            n = write(p->fd, &image, sizeof(image));
+            if (n == sizeof(image))
+            {
+                p->time_last_written = p->time;
+                p->id_last_written = p->id;
+                dmsg(D_PID_PERSIST_DEBUG, "PID Persist Write to %s: %s",
+                     p->filename, packet_id_persist_print(p, &gc));
+            }
+            else
+            {
+                msg(D_PID_PERSIST | M_ERRNO,
+                    "Cannot write to --replay-persist file %s",
+                    p->filename);
+            }
+        }
+        else
+        {
+            msg(D_PID_PERSIST | M_ERRNO,
+                "Cannot seek to beginning of --replay-persist file %s",
+                p->filename);
+        }
+        gc_free(&gc);
+    }
+}
+
+/* transfer packet_id_persist -> packet_id */
+void
+packet_id_persist_load_obj(const struct packet_id_persist *p, struct packet_id *pid)
+{
+    if (p && pid && packet_id_persist_enabled(p) && p->time)
+    {
+        pid->rec.time = p->time;
+        pid->rec.id = p->id;
+    }
+}
+
+const char *
+packet_id_persist_print(const struct packet_id_persist *p, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    buf_printf(&out, "[");
+
+    if (packet_id_persist_enabled(p))
+    {
+        buf_printf(&out, " #" packet_id_format, (packet_id_print_type)p->id);
+        if (p->time)
+        {
+            buf_printf(&out, " / time = (" packet_id_format ") %s",
+                       (packet_id_print_type)p->time,
+                       time_string(p->time, 0, false, gc));
+        }
+    }
+
+    buf_printf(&out, " ]");
+    return (char *)out.data;
+}
+
+#ifdef ENABLE_DEBUG
+
+static void
+packet_id_debug_print(int msglevel,
+                      const struct packet_id_rec *p,
+                      const struct packet_id_net *pin,
+                      const char *message,
+                      int value)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer out = alloc_buf_gc(256, &gc);
+    struct timeval tv;
+    const time_t prev_now = now;
+    const struct seq_list *sl = p->seq_list;
+    int i;
+
+    CLEAR(tv);
+    gettimeofday(&tv, NULL);
+
+    buf_printf(&out, "%s [%d]", message, value);
+    buf_printf(&out, " [%s-%d] [", p->name, p->unit);
+    for (i = 0; sl != NULL && i < sl->x_size; ++i)
+    {
+        char c;
+        time_t v;
+        int diff;
+
+        v = CIRC_LIST_ITEM(sl, i);
+        if (v == SEQ_UNSEEN)
+        {
+            c = '_';
+        }
+        else if (v == SEQ_EXPIRED)
+        {
+            c = 'E';
+        }
+        else
+        {
+            diff = (int) prev_now - v;
+            if (diff < 0)
+            {
+                c = 'N';
+            }
+            else if (diff < 10)
+            {
+                c = '0' + diff;
+            }
+            else
+            {
+                c = '>';
+            }
+        }
+        buf_printf(&out, "%c", c);
+    }
+    buf_printf(&out, "] " time_format ":" packet_id_format, (time_type)p->time, (packet_id_print_type)p->id);
+    if (pin)
+    {
+        buf_printf(&out, " " time_format ":" packet_id_format, (time_type)pin->time, (packet_id_print_type)pin->id);
+    }
+
+    buf_printf(&out, " t=" time_format "[%d]",
+               (time_type)prev_now,
+               (int)(prev_now - tv.tv_sec));
+
+    buf_printf(&out, " r=[%d,%d,%d,%d,%d]",
+               (int)(p->last_reap - tv.tv_sec),
+               p->seq_backtrack,
+               p->time_backtrack,
+               p->max_backtrack_stat,
+               (int)p->initialized);
+    if (sl != NULL)
+    {
+        buf_printf(&out, " sl=[%d,%d,%d,%d]",
+                   sl->x_head,
+                   sl->x_size,
+                   sl->x_cap,
+                   sl->x_sizeof);
+    }
+
+
+    msg(msglevel, "%s", BSTR(&out));
+    gc_free(&gc);
+}
+
+#endif /* ifdef ENABLE_DEBUG */
+
+#ifdef PID_TEST
+
+void
+packet_id_interactive_test(void)
+{
+    struct packet_id pid;
+    struct packet_id_net pin;
+    bool long_form;
+    bool count = 0;
+    bool test;
+
+    const int seq_backtrack = 10;
+    const int time_backtrack = 10;
+
+    packet_id_init(&pid, seq_backtrack, time_backtrack);
+
+    while (true)
+    {
+        char buf[80];
+        if (!fgets(buf, sizeof(buf), stdin))
+        {
+            break;
+        }
+        update_time();
+        if (sscanf(buf, "%lu,%u", &pin.time, &pin.id) == 2)
+        {
+            packet_id_reap_test(&pid.rec);
+            test = packet_id_test(&pid.rec, &pin);
+            printf("packet_id_test (" time_format ", " packet_id_format ") returned %d\n",
+                   (time_type)pin.time,
+                   (packet_id_print_type)pin.id,
+                   test);
+            if (test)
+            {
+                packet_id_add(&pid.rec, &pin);
+            }
+        }
+        else
+        {
+            long_form = (count < 20);
+            packet_id_alloc_outgoing(&pid.send, &pin, long_form);
+            printf("(" time_format "(" packet_id_format "), %d)\n",
+                   (time_type)pin.time,
+                   (packet_id_print_type)pin.id,
+                   long_form);
+            if (pid.send.id == 10)
+            {
+                pid.send.id = 0xFFFFFFF8;
+            }
+            ++count;
+        }
+    }
+    packet_id_free(&pid);
+}
+#endif /* ifdef PID_TEST */
+
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/packet_id.h b/src/openvpn/packet_id.h
new file mode 100644
index 0000000..f984e7c
--- /dev/null
+++ b/src/openvpn/packet_id.h
@@ -0,0 +1,345 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * These routines are designed to catch replay attacks,
+ * where a man-in-the-middle captures packets and then
+ * attempts to replay them back later.
+ */
+
+#ifdef ENABLE_CRYPTO
+
+#ifndef PACKET_ID_H
+#define PACKET_ID_H
+
+#include "circ_list.h"
+#include "buffer.h"
+#include "error.h"
+#include "otime.h"
+
+/*
+ * Enables OpenVPN to be compiled in special packet_id test mode.
+ */
+/*#define PID_TEST*/
+
+#if 1
+/*
+ * These are the types that members of
+ * a struct packet_id_net are converted
+ * to for network transmission.
+ */
+typedef uint32_t packet_id_type;
+#define PACKET_ID_MAX UINT32_MAX
+typedef uint32_t net_time_t;
+
+/*
+ * In TLS mode, when a packet ID gets to this level,
+ * start thinking about triggering a new
+ * SSL/TLS handshake.
+ */
+#define PACKET_ID_WRAP_TRIGGER 0xFF000000
+
+/* convert a packet_id_type from host to network order */
+#define htonpid(x) htonl(x)
+
+/* convert a packet_id_type from network to host order */
+#define ntohpid(x) ntohl(x)
+
+/* convert a time_t in host order to a net_time_t in network order */
+#define htontime(x) htonl((net_time_t)x)
+
+/* convert a net_time_t in network order to a time_t in host order */
+#define ntohtime(x) ((time_t)ntohl(x))
+
+#else  /* if 1 */
+
+/*
+ * DEBUGGING ONLY.
+ * Make packet_id_type and net_time_t small
+ * to test wraparound logic and corner cases.
+ */
+
+typedef uint8_t packet_id_type;
+typedef uint16_t net_time_t;
+
+#define PACKET_ID_WRAP_TRIGGER 0x80
+
+#define htonpid(x) (x)
+#define ntohpid(x) (x)
+#define htontime(x) htons((net_time_t)x)
+#define ntohtime(x) ((time_t)ntohs(x))
+
+#endif /* if 1 */
+
+/*
+ * Printf formats for special types
+ */
+#define packet_id_format "%u"
+typedef unsigned int packet_id_print_type;
+
+/*
+ * Maximum allowed backtrack in
+ * sequence number due to packets arriving
+ * out of order.
+ */
+#define MIN_SEQ_BACKTRACK 0
+#define MAX_SEQ_BACKTRACK 65536
+#define DEFAULT_SEQ_BACKTRACK 64
+
+/*
+ * Maximum allowed backtrack in
+ * seconds due to packets arriving
+ * out of order.
+ */
+#define MIN_TIME_BACKTRACK 0
+#define MAX_TIME_BACKTRACK 600
+#define DEFAULT_TIME_BACKTRACK 15
+
+/*
+ * Do a reap pass through the sequence number
+ * array once every n seconds in order to
+ * expire sequence numbers which can no longer
+ * be accepted because they would violate
+ * TIME_BACKTRACK.
+ */
+#define SEQ_REAP_INTERVAL 5
+
+CIRC_LIST(seq_list, time_t);
+
+/*
+ * This is the data structure we keep on the receiving side,
+ * to check that no packet-id (i.e. sequence number + optional timestamp)
+ * is accepted more than once.
+ */
+struct packet_id_rec
+{
+    time_t last_reap;         /* last call of packet_id_reap */
+    time_t time;              /* highest time stamp received */
+    packet_id_type id;        /* highest sequence number received */
+    int seq_backtrack;        /* set from --replay-window */
+    int time_backtrack;       /* set from --replay-window */
+    int max_backtrack_stat;   /* maximum backtrack seen so far */
+    bool initialized;         /* true if packet_id_init was called */
+    struct seq_list *seq_list; /* packet-id "memory" */
+    const char *name;
+    int unit;
+};
+
+/*
+ * file to facilitate cross-session persistence
+ * of time/id
+ */
+struct packet_id_persist
+{
+    const char *filename;
+    int fd;
+    time_t time;           /* time stamp */
+    packet_id_type id;     /* sequence number */
+    time_t time_last_written;
+    packet_id_type id_last_written;
+};
+
+struct packet_id_persist_file_image
+{
+    time_t time;           /* time stamp */
+    packet_id_type id;     /* sequence number */
+};
+
+/*
+ * Keep a record of our current packet-id state
+ * on the sending side.
+ */
+struct packet_id_send
+{
+    packet_id_type id;
+    time_t time;
+};
+
+/*
+ * Communicate packet-id over the wire.
+ * A short packet-id is just a 32 bit
+ * sequence number.  A long packet-id
+ * includes a timestamp as well.
+ *
+ * Long packet-ids are used as IVs for
+ * CFB/OFB ciphers.
+ *
+ * This data structure is always sent
+ * over the net in network byte order,
+ * by calling htonpid, ntohpid,
+ * htontime, and ntohtime on the
+ * data elements to change them
+ * to and from standard sizes.
+ *
+ * In addition, time is converted to
+ * a net_time_t before sending,
+ * since openvpn always
+ * uses a 32-bit time_t but some
+ * 64 bit platforms use a
+ * 64 bit time_t.
+ */
+struct packet_id_net
+{
+    packet_id_type id;
+    time_t time; /* converted to net_time_t before transmission */
+};
+
+struct packet_id
+{
+    struct packet_id_send send;
+    struct packet_id_rec rec;
+};
+
+void packet_id_init(struct packet_id *p, int seq_backtrack, int time_backtrack, const char *name, int unit);
+
+void packet_id_free(struct packet_id *p);
+
+/* should we accept an incoming packet id ? */
+bool packet_id_test(struct packet_id_rec *p,
+                    const struct packet_id_net *pin);
+
+/* change our current state to reflect an accepted packet id */
+void packet_id_add(struct packet_id_rec *p,
+                   const struct packet_id_net *pin);
+
+/* expire TIME_BACKTRACK sequence numbers */
+void packet_id_reap(struct packet_id_rec *p);
+
+/*
+ * packet ID persistence
+ */
+
+/* initialize the packet_id_persist structure in a disabled state */
+void packet_id_persist_init(struct packet_id_persist *p);
+
+/* close the file descriptor if it is open, and switch to disabled state */
+void packet_id_persist_close(struct packet_id_persist *p);
+
+/* load persisted rec packet_id (time and id) only once from file, and set state to enabled */
+void packet_id_persist_load(struct packet_id_persist *p, const char *filename);
+
+/* save persisted rec packet_id (time and id) to file (only if enabled state) */
+void packet_id_persist_save(struct packet_id_persist *p);
+
+/* transfer packet_id_persist -> packet_id */
+void packet_id_persist_load_obj(const struct packet_id_persist *p, struct packet_id *pid);
+
+/* return an ascii string representing a packet_id_persist object */
+const char *packet_id_persist_print(const struct packet_id_persist *p, struct gc_arena *gc);
+
+/*
+ * Read/write a packet ID to/from the buffer.  Short form is sequence number
+ * only.  Long form is sequence number and timestamp.
+ */
+
+bool packet_id_read(struct packet_id_net *pin, struct buffer *buf, bool long_form);
+
+/**
+ * Write a packet ID to buf, and update the packet ID state.
+ *
+ * @param p             Packet ID state.
+ * @param buf           Buffer to write the packet ID too
+ * @param long_form     If true, also update and write time_t to buf
+ * @param prepend       If true, prepend to buffer, otherwise apppend.
+ *
+ * @return true if successful, false otherwise.
+ */
+bool packet_id_write(struct packet_id_send *p, struct buffer *buf,
+        bool long_form, bool prepend);
+
+/*
+ * Inline functions.
+ */
+
+/** Is this struct packet_id initialized? */
+static inline bool
+packet_id_initialized(const struct packet_id *pid)
+{
+    return pid->rec.initialized;
+}
+
+/* are we in enabled state? */
+static inline bool
+packet_id_persist_enabled(const struct packet_id_persist *p)
+{
+    return p->fd >= 0;
+}
+
+/* transfer packet_id -> packet_id_persist */
+static inline void
+packet_id_persist_save_obj(struct packet_id_persist *p, const struct packet_id *pid)
+{
+    if (packet_id_persist_enabled(p) && pid->rec.time)
+    {
+        p->time = pid->rec.time;
+        p->id = pid->rec.id;
+    }
+}
+
+const char *packet_id_net_print(const struct packet_id_net *pin, bool print_timestamp, struct gc_arena *gc);
+
+#ifdef PID_TEST
+void packet_id_interactive_test(void);
+
+#endif
+
+static inline int
+packet_id_size(bool long_form)
+{
+    return sizeof(packet_id_type) + (long_form ? sizeof(net_time_t) : 0);
+}
+
+static inline bool
+packet_id_close_to_wrapping(const struct packet_id_send *p)
+{
+    return p->id >= PACKET_ID_WRAP_TRIGGER;
+}
+
+static inline bool
+check_timestamp_delta(time_t remote, unsigned int max_delta)
+{
+    unsigned int abs;
+    const time_t local_now = now;
+
+    if (local_now >= remote)
+    {
+        abs = local_now - remote;
+    }
+    else
+    {
+        abs = remote - local_now;
+    }
+    return abs <= max_delta;
+}
+
+static inline void
+packet_id_reap_test(struct packet_id_rec *p)
+{
+    if (p->last_reap + SEQ_REAP_INTERVAL <= now)
+    {
+        packet_id_reap(p);
+    }
+}
+
+#endif /* PACKET_ID_H */
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/perf.c b/src/openvpn/perf.c
new file mode 100644
index 0000000..d882358
--- /dev/null
+++ b/src/openvpn/perf.c
@@ -0,0 +1,329 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "perf.h"
+
+#ifdef ENABLE_PERFORMANCE_METRICS
+
+#include "error.h"
+#include "otime.h"
+
+#include "memdbg.h"
+
+static const char *metric_names[] = {
+    "PERF_BIO_READ_PLAINTEXT",
+    "PERF_BIO_WRITE_PLAINTEXT",
+    "PERF_BIO_READ_CIPHERTEXT",
+    "PERF_BIO_WRITE_CIPHERTEXT",
+    "PERF_TLS_MULTI_PROCESS",
+    "PERF_IO_WAIT",
+    "PERF_EVENT_LOOP",
+    "PERF_MULTI_CREATE_INSTANCE",
+    "PERF_MULTI_CLOSE_INSTANCE",
+    "PERF_MULTI_SHOW_STATS",
+    "PERF_MULTI_BCAST",
+    "PERF_MULTI_MCAST",
+    "PERF_SCRIPT",
+    "PERF_READ_IN_LINK",
+    "PERF_PROC_IN_LINK",
+    "PERF_READ_IN_TUN",
+    "PERF_PROC_IN_TUN",
+    "PERF_PROC_OUT_LINK",
+    "PERF_PROC_OUT_TUN",
+    "PERF_PROC_OUT_TUN_MTCP"
+};
+
+struct perf
+{
+#define PS_INITIAL            0
+#define PS_METER_RUNNING      1
+#define PS_METER_INTERRUPTED  2
+    int state;
+
+    struct timeval start;
+    double sofar;
+    double sum;
+    double max;
+    double count;
+};
+
+struct perf_set
+{
+    int stack_len;
+    int stack[STACK_N];
+    struct perf perf[PERF_N];
+};
+
+static struct perf_set perf_set;
+
+static void perf_print_state(int lev);
+
+static inline int
+get_stack_index(int sdelta)
+{
+    const int sindex = perf_set.stack_len + sdelta;
+    if (sindex >= 0 && sindex < STACK_N)
+    {
+        return sindex;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+static int
+get_perf_index(int sdelta)
+{
+    const int sindex = get_stack_index(sdelta);
+    if (sindex >= 0)
+    {
+        const int pindex = perf_set.stack[sindex];
+        if (pindex >= 0 && pindex < PERF_N)
+        {
+            return pindex;
+        }
+        else
+        {
+            return -1;
+        }
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+static struct perf *
+get_perf(int sdelta)
+{
+    const int pindex = get_perf_index(sdelta);
+    if (pindex >= 0)
+    {
+        return &perf_set.perf[pindex];
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+static void
+push_perf_index(int pindex)
+{
+    const int sindex = get_stack_index(0);
+    const int newlen = get_stack_index(1);
+    if (sindex >= 0 && newlen >= 0
+        && pindex >= 0 && pindex < PERF_N)
+    {
+        int i;
+        for (i = 0; i < sindex; ++i)
+        {
+            if (perf_set.stack[i] == pindex)
+            {
+                perf_print_state(M_INFO);
+                msg(M_FATAL, "PERF: push_perf_index %s failed",
+                    metric_names [pindex]);
+            }
+        }
+
+        perf_set.stack[sindex] = pindex;
+        perf_set.stack_len = newlen;
+    }
+    else
+    {
+        msg(M_FATAL, "PERF: push_perf_index: stack push error");
+    }
+}
+
+static void
+pop_perf_index(void)
+{
+    const int newlen = get_stack_index(-1);
+    if (newlen >= 0)
+    {
+        perf_set.stack_len = newlen;
+    }
+    else
+    {
+        msg(M_FATAL, "PERF: pop_perf_index: stack pop error");
+    }
+}
+
+static void
+state_must_be(const struct perf *p, const int wanted)
+{
+    if (p->state != wanted)
+    {
+        msg(M_FATAL, "PERF: bad state actual=%d wanted=%d",
+            p->state,
+            wanted);
+    }
+}
+
+static void
+update_sofar(struct perf *p)
+{
+    struct timeval current;
+    ASSERT(!gettimeofday(&current, NULL));
+    p->sofar += (double) tv_subtract(&current, &p->start, 600) / 1000000.0;
+    tv_clear(&p->start);
+}
+
+static void
+perf_start(struct perf *p)
+{
+    state_must_be(p, PS_INITIAL);
+    ASSERT(!gettimeofday(&p->start, NULL));
+    p->sofar = 0.0;
+    p->state = PS_METER_RUNNING;
+}
+
+static void
+perf_stop(struct perf *p)
+{
+    state_must_be(p, PS_METER_RUNNING);
+    update_sofar(p);
+    p->sum += p->sofar;
+    if (p->sofar > p->max)
+    {
+        p->max = p->sofar;
+    }
+    p->count += 1.0;
+    p->sofar = 0.0;
+    p->state = PS_INITIAL;
+}
+
+static void
+perf_interrupt(struct perf *p)
+{
+    state_must_be(p, PS_METER_RUNNING);
+    update_sofar(p);
+    p->state = PS_METER_INTERRUPTED;
+}
+
+static void
+perf_resume(struct perf *p)
+{
+    state_must_be(p, PS_METER_INTERRUPTED);
+    ASSERT(!gettimeofday(&p->start, NULL));
+    p->state = PS_METER_RUNNING;
+}
+
+void
+perf_push(int type)
+{
+    struct perf *prev;
+    struct perf *cur;
+
+    ASSERT(SIZE(metric_names) == PERF_N);
+    push_perf_index(type);
+
+    prev = get_perf(-2);
+    cur = get_perf(-1);
+
+    ASSERT(cur);
+
+    if (prev)
+    {
+        perf_interrupt(prev);
+    }
+    perf_start(cur);
+}
+
+void
+perf_pop(void)
+{
+    struct perf *prev;
+    struct perf *cur;
+
+    prev = get_perf(-2);
+    cur = get_perf(-1);
+
+    ASSERT(cur);
+    perf_stop(cur);
+
+    if (prev)
+    {
+        perf_resume(prev);
+    }
+
+    pop_perf_index();
+}
+
+void
+perf_output_results(void)
+{
+    int i;
+    msg(M_INFO, "LATENCY PROFILE (mean and max are in milliseconds)");
+    for (i = 0; i < PERF_N; ++i)
+    {
+        struct perf *p = &perf_set.perf[i];
+        if (p->count > 0.0)
+        {
+            const double mean = p->sum / p->count;
+            msg(M_INFO, "%s n=%.0f mean=%.3f max=%.3f", metric_names[i], p->count, mean*1000.0, p->max*1000.0);
+        }
+    }
+}
+
+static void
+perf_print_state(int lev)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    msg(lev, "PERF STATE");
+    msg(lev, "Stack:");
+    for (i = 0; i < perf_set.stack_len; ++i)
+    {
+        const int j = perf_set.stack[i];
+        const struct perf *p = &perf_set.perf[j];
+        msg(lev, "[%d] %s state=%d start=%s sofar=%f sum=%f max=%f count=%f",
+            i,
+            metric_names[j],
+            p->state,
+            tv_string(&p->start, &gc),
+            p->sofar,
+            p->sum,
+            p->max,
+            p->count);
+    }
+    gc_free(&gc);
+}
+
+#else  /* ifdef ENABLE_PERFORMANCE_METRICS */
+#ifdef _MSC_VER  /* Dummy function needed to avoid empty file compiler warning in Microsoft VC */
+static void
+dummy(void)
+{
+}
+#endif
+#endif /* ifdef ENABLE_PERFORMANCE_METRICS */
diff --git a/src/openvpn/perf.h b/src/openvpn/perf.h
new file mode 100644
index 0000000..9cf0343
--- /dev/null
+++ b/src/openvpn/perf.h
@@ -0,0 +1,92 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * The interval_ routines are designed to optimize the calling of a routine
+ * (normally tls_multi_process()) which can be called less frequently
+ * between triggers.
+ */
+
+#ifndef PERF_H
+#define PERF_H
+
+/*#define ENABLE_PERFORMANCE_METRICS*/
+
+/*
+ * Metrics
+ */
+#define PERF_BIO_READ_PLAINTEXT     0
+#define PERF_BIO_WRITE_PLAINTEXT    1
+#define PERF_BIO_READ_CIPHERTEXT    2
+#define PERF_BIO_WRITE_CIPHERTEXT   3
+#define PERF_TLS_MULTI_PROCESS      4
+#define PERF_IO_WAIT                5
+#define PERF_EVENT_LOOP             6
+#define PERF_MULTI_CREATE_INSTANCE  7
+#define PERF_MULTI_CLOSE_INSTANCE   8
+#define PERF_MULTI_SHOW_STATS       9
+#define PERF_MULTI_BCAST            10
+#define PERF_MULTI_MCAST            11
+#define PERF_SCRIPT                 12
+#define PERF_READ_IN_LINK           13
+#define PERF_PROC_IN_LINK           14
+#define PERF_READ_IN_TUN            15
+#define PERF_PROC_IN_TUN            16
+#define PERF_PROC_OUT_LINK          17
+#define PERF_PROC_OUT_TUN           18
+#define PERF_PROC_OUT_TUN_MTCP      19
+#define PERF_N                      20
+
+#ifdef ENABLE_PERFORMANCE_METRICS
+
+#include "basic.h"
+
+/*
+ * Stack size
+ */
+#define STACK_N               64
+
+void perf_push(int type);
+
+void perf_pop(void);
+
+void perf_output_results(void);
+
+#else  /* ifdef ENABLE_PERFORMANCE_METRICS */
+
+static inline void
+perf_push(int type)
+{
+}
+static inline void
+perf_pop(void)
+{
+}
+static inline void
+perf_output_results(void)
+{
+}
+
+#endif /* ifdef ENABLE_PERFORMANCE_METRICS */
+
+#endif /* ifndef PERF_H */
diff --git a/src/openvpn/pf-inline.h b/src/openvpn/pf-inline.h
new file mode 100644
index 0000000..90cc41c
--- /dev/null
+++ b/src/openvpn/pf-inline.h
@@ -0,0 +1,63 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#if defined(ENABLE_PF) && !defined(PF_INLINE_H)
+#define PF_INLINE_H
+
+/*
+ * Inline functions
+ */
+
+#define PCT_SRC  1
+#define PCT_DEST 2
+static inline bool
+pf_c2c_test(const struct context *src, const struct context *dest, const char *prefix)
+{
+    bool pf_cn_test(struct pf_set *pfs, const struct tls_multi *tm, const int type, const char *prefix);
+
+    return (!src->c2.pf.enabled  || pf_cn_test(src->c2.pf.pfs,  dest->c2.tls_multi, PCT_DEST, prefix))
+           && (!dest->c2.pf.enabled || pf_cn_test(dest->c2.pf.pfs, src->c2.tls_multi,  PCT_SRC,  prefix));
+}
+
+static inline bool
+pf_addr_test(const struct context *src, const struct mroute_addr *dest, const char *prefix)
+{
+    bool pf_addr_test_dowork(const struct context *src, const struct mroute_addr *dest, const char *prefix);
+
+    if (src->c2.pf.enabled)
+    {
+        return pf_addr_test_dowork(src, dest, prefix);
+    }
+    else
+    {
+        return true;
+    }
+}
+
+static inline bool
+pf_kill_test(const struct pf_set *pfs)
+{
+    return pfs->kill;
+}
+
+#endif /* if defined(ENABLE_PF) && !defined(PF_INLINE_H) */
diff --git a/src/openvpn/pf.c b/src/openvpn/pf.c
new file mode 100644
index 0000000..7277ae6
--- /dev/null
+++ b/src/openvpn/pf.c
@@ -0,0 +1,780 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* packet filter functions */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_PF)
+
+#include "init.h"
+#include "memdbg.h"
+#include "ssl_verify.h"
+
+#include "pf-inline.h"
+
+static void
+pf_destroy(struct pf_set *pfs)
+{
+    if (pfs)
+    {
+        if (pfs->cns.hash_table)
+        {
+            hash_free(pfs->cns.hash_table);
+        }
+
+        {
+            struct pf_cn_elem *l = pfs->cns.list;
+            while (l)
+            {
+                struct pf_cn_elem *next = l->next;
+                free(l->rule.cn);
+                free(l);
+                l = next;
+            }
+        }
+        {
+            struct pf_subnet *l = pfs->sns.list;
+            while (l)
+            {
+                struct pf_subnet *next = l->next;
+                free(l);
+                l = next;
+            }
+        }
+        free(pfs);
+    }
+}
+
+static bool
+add_client(const char *line, const char *prefix, const int line_num, struct pf_cn_elem ***next, const bool exclude)
+{
+    struct pf_cn_elem *e;
+    ALLOC_OBJ_CLEAR(e, struct pf_cn_elem);
+    e->rule.exclude = exclude;
+    e->rule.cn = string_alloc(line, NULL);
+    **next = e;
+    *next = &e->next;
+    return true;
+}
+
+static bool
+add_subnet(const char *line, const char *prefix, const int line_num, struct pf_subnet ***next, const bool exclude)
+{
+    struct in_addr network;
+    in_addr_t netmask = 0;
+
+    if (strcmp(line, "unknown"))
+    {
+        int netbits = 32;
+        char *div = strchr(line, '/');
+
+        if (div)
+        {
+            *div++ = '\0';
+            if (sscanf(div, "%d", &netbits) != 1)
+            {
+                msg(D_PF_INFO, "PF: %s/%d: bad '/n' subnet specifier: '%s'", prefix, line_num, div);
+                return false;
+            }
+            if (netbits < 0 || netbits > 32)
+            {
+                msg(D_PF_INFO, "PF: %s/%d: bad '/n' subnet specifier: must be between 0 and 32: '%s'", prefix, line_num, div);
+                return false;
+            }
+        }
+
+        if (openvpn_inet_aton(line, &network) != OIA_IP)
+        {
+            msg(D_PF_INFO, "PF: %s/%d: bad network address: '%s'", prefix, line_num, line);
+            return false;
+        }
+        netmask = netbits_to_netmask(netbits);
+        if ((network.s_addr & htonl(netmask)) != network.s_addr)
+        {
+            network.s_addr &= htonl(netmask);
+            msg(M_WARN, "WARNING: PF: %s/%d: incorrect subnet %s/%d changed to %s/%d", prefix, line_num, line, netbits, inet_ntoa(network), netbits);
+        }
+    }
+    else
+    {
+        /* match special "unknown" tag for addresses unrecognized by mroute */
+        network.s_addr = htonl(0);
+        netmask = IPV4_NETMASK_HOST;
+    }
+
+    {
+        struct pf_subnet *e;
+        ALLOC_OBJ_CLEAR(e, struct pf_subnet);
+        e->rule.exclude = exclude;
+        e->rule.network = ntohl(network.s_addr);
+        e->rule.netmask = netmask;
+        **next = e;
+        *next = &e->next;
+        return true;
+    }
+}
+
+static uint32_t
+cn_hash_function(const void *key, uint32_t iv)
+{
+    return hash_func((uint8_t *)key, strlen((char *)key) + 1, iv);
+}
+
+static bool
+cn_compare_function(const void *key1, const void *key2)
+{
+    return !strcmp((const char *)key1, (const char *)key2);
+}
+
+static bool
+genhash(struct pf_cn_set *cns, const char *prefix, const int n_clients)
+{
+    struct pf_cn_elem *e;
+    bool status = true;
+    int n_buckets = n_clients;
+
+    if (n_buckets < 16)
+    {
+        n_buckets = 16;
+    }
+    cns->hash_table = hash_init(n_buckets, 0, cn_hash_function, cn_compare_function);
+    for (e = cns->list; e != NULL; e = e->next)
+    {
+        if (!hash_add(cns->hash_table, e->rule.cn, &e->rule, false))
+        {
+            msg(D_PF_INFO, "PF: %s: duplicate common name in [clients] section: '%s'", prefix, e->rule.cn);
+            status = false;
+        }
+    }
+
+    return status;
+}
+
+static struct pf_set *
+pf_init(const struct buffer_list *bl, const char *prefix, const bool allow_kill)
+{
+#define MODE_UNDEF   0
+#define MODE_CLIENTS 1
+#define MODE_SUBNETS 2
+    int mode = MODE_UNDEF;
+    int line_num = 0;
+    int n_clients = 0;
+    int n_subnets = 0;
+    int n_errors = 0;
+    struct pf_set *pfs = NULL;
+    char line[PF_MAX_LINE_LEN];
+
+    ALLOC_OBJ_CLEAR(pfs, struct pf_set);
+    if (bl)
+    {
+        struct pf_cn_elem **cl = &pfs->cns.list;
+        struct pf_subnet **sl = &pfs->sns.list;
+        struct buffer_entry *be;
+
+        for (be = bl->head; be != NULL; be = be->next)
+        {
+            ++line_num;
+            strncpynt(line, BSTR(&be->buf), sizeof(line));
+            rm_trailing_chars(line, "\r\n\t ");
+            if (line[0] == '\0' || line[0] == '#')
+            {
+            }
+            else if (line[0] == '+' || line[0] == '-')
+            {
+                bool exclude = (line[0] == '-');
+
+                if (line[1] =='\0')
+                {
+                    msg(D_PF_INFO, "PF: %s/%d: no data after +/-: '%s'", prefix, line_num, line);
+                    ++n_errors;
+                }
+                else if (mode == MODE_CLIENTS)
+                {
+                    if (add_client(&line[1], prefix, line_num, &cl, exclude))
+                    {
+                        ++n_clients;
+                    }
+                    else
+                    {
+                        ++n_errors;
+                    }
+                }
+                else if (mode == MODE_SUBNETS)
+                {
+                    if (add_subnet(&line[1], prefix, line_num, &sl, exclude))
+                    {
+                        ++n_subnets;
+                    }
+                    else
+                    {
+                        ++n_errors;
+                    }
+                }
+                else if (mode == MODE_UNDEF)
+                {
+                }
+                else
+                {
+                    ASSERT(0);
+                }
+            }
+            else if (line[0] == '[')
+            {
+                if (!strcasecmp(line, "[clients accept]"))
+                {
+                    mode = MODE_CLIENTS;
+                    pfs->cns.default_allow = true;
+                }
+                else if (!strcasecmp(line, "[clients drop]"))
+                {
+                    mode = MODE_CLIENTS;
+                    pfs->cns.default_allow = false;
+                }
+                else if (!strcasecmp(line, "[subnets accept]"))
+                {
+                    mode = MODE_SUBNETS;
+                    pfs->sns.default_allow = true;
+                }
+                else if (!strcasecmp(line, "[subnets drop]"))
+                {
+                    mode = MODE_SUBNETS;
+                    pfs->sns.default_allow = false;
+                }
+                else if (!strcasecmp(line, "[end]"))
+                {
+                    goto done;
+                }
+                else if (allow_kill && !strcasecmp(line, "[kill]"))
+                {
+                    goto kill;
+                }
+                else
+                {
+                    mode = MODE_UNDEF;
+                    msg(D_PF_INFO, "PF: %s/%d unknown tag: '%s'", prefix, line_num, line);
+                    ++n_errors;
+                }
+            }
+            else
+            {
+                msg(D_PF_INFO, "PF: %s/%d line must begin with '+', '-', or '[' : '%s'", prefix, line_num, line);
+                ++n_errors;
+            }
+        }
+        ++n_errors;
+        msg(D_PF_INFO, "PF: %s: missing [end]", prefix);
+    }
+    else
+    {
+        msg(D_PF_INFO, "PF: %s: cannot open", prefix);
+        ++n_errors;
+    }
+
+done:
+    if (bl)
+    {
+        if (!n_errors)
+        {
+            if (!genhash(&pfs->cns, prefix, n_clients))
+            {
+                ++n_errors;
+            }
+        }
+        if (n_errors)
+        {
+            msg(D_PF_INFO, "PF: %s rejected due to %d error(s)", prefix, n_errors);
+        }
+    }
+    if (n_errors)
+    {
+        pf_destroy(pfs);
+        pfs = NULL;
+    }
+    return pfs;
+
+kill:
+    pf_destroy(pfs);
+    ALLOC_OBJ_CLEAR(pfs, struct pf_set);
+    pfs->kill = true;
+    return pfs;
+}
+
+#ifdef PLUGIN_PF
+static struct pf_set *
+pf_init_from_file(const char *fn)
+{
+    struct buffer_list *bl = buffer_list_file(fn, PF_MAX_LINE_LEN);
+    if (bl)
+    {
+        struct pf_set *pfs = pf_init(bl, fn, true);
+        buffer_list_free(bl);
+        return pfs;
+    }
+    else
+    {
+        msg(D_PF_INFO|M_ERRNO, "PF: %s: cannot open", fn);
+        return NULL;
+    }
+}
+#endif
+
+#ifdef ENABLE_DEBUG
+
+static const char *
+drop_accept(const bool accept)
+{
+    return accept ? "ACCEPT" : "DROP";
+}
+
+static const char *
+pct_name(const int type)
+{
+    switch (type)
+    {
+        case PCT_SRC:
+            return "SRC";
+
+        case PCT_DEST:
+            return "DEST";
+
+        default:
+            return "???";
+    }
+}
+
+static void
+pf_cn_test_print(const char *prefix,
+                 const int type,
+                 const char *prefix2,
+                 const char *cn,
+                 const bool allow,
+                 const struct pf_cn *rule)
+{
+    if (rule)
+    {
+        dmsg(D_PF_DEBUG, "PF: %s/%s/%s %s %s rule=[%s %s]",
+             prefix, prefix2, pct_name(type),
+             cn, drop_accept(allow),
+             rule->cn, drop_accept(!rule->exclude));
+    }
+    else
+    {
+        dmsg(D_PF_DEBUG, "PF: %s/%s/%s %s %s",
+             prefix, prefix2, pct_name(type),
+             cn, drop_accept(allow));
+    }
+}
+
+static void
+pf_addr_test_print(const char *prefix,
+                   const char *prefix2,
+                   const struct context *src,
+                   const struct mroute_addr *dest,
+                   const bool allow,
+                   const struct ipv4_subnet *rule)
+{
+    struct gc_arena gc = gc_new();
+    if (rule)
+    {
+        dmsg(D_PF_DEBUG, "PF: %s/%s %s %s %s rule=[%s/%s %s]",
+             prefix,
+             prefix2,
+             tls_common_name(src->c2.tls_multi, false),
+             mroute_addr_print_ex(dest, MAPF_SHOW_ARP, &gc),
+             drop_accept(allow),
+             print_in_addr_t(rule->network, 0, &gc),
+             print_in_addr_t(rule->netmask, 0, &gc),
+             drop_accept(!rule->exclude));
+    }
+    else
+    {
+        dmsg(D_PF_DEBUG, "PF: %s/%s %s %s %s",
+             prefix,
+             prefix2,
+             tls_common_name(src->c2.tls_multi, false),
+             mroute_addr_print_ex(dest, MAPF_SHOW_ARP, &gc),
+             drop_accept(allow));
+    }
+    gc_free(&gc);
+}
+
+#endif /* ifdef ENABLE_DEBUG */
+
+static inline struct pf_cn *
+lookup_cn_rule(struct hash *h, const char *cn, const uint32_t cn_hash)
+{
+    struct hash_element *he = hash_lookup_fast(h, hash_bucket(h, cn_hash), cn, cn_hash);
+    if (he)
+    {
+        return (struct pf_cn *) he->value;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+bool
+pf_cn_test(struct pf_set *pfs, const struct tls_multi *tm, const int type, const char *prefix)
+{
+    if (pfs && !pfs->kill)
+    {
+        const char *cn;
+        uint32_t cn_hash;
+        if (tls_common_name_hash(tm, &cn, &cn_hash))
+        {
+            const struct pf_cn *rule = lookup_cn_rule(pfs->cns.hash_table, cn, cn_hash);
+            if (rule)
+            {
+#ifdef ENABLE_DEBUG
+                if (check_debug_level(D_PF_DEBUG))
+                {
+                    pf_cn_test_print("PF_CN_MATCH", type, prefix, cn, !rule->exclude, rule);
+                }
+#endif
+                if (!rule->exclude)
+                {
+                    return true;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            else
+            {
+#ifdef ENABLE_DEBUG
+                if (check_debug_level(D_PF_DEBUG))
+                {
+                    pf_cn_test_print("PF_CN_DEFAULT", type, prefix, cn, pfs->cns.default_allow, NULL);
+                }
+#endif
+                if (pfs->cns.default_allow)
+                {
+                    return true;
+                }
+                else
+                {
+                    return false;
+                }
+            }
+        }
+    }
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_PF_DEBUG))
+    {
+        pf_cn_test_print("PF_CN_FAULT", type, prefix, tls_common_name(tm, false), false, NULL);
+    }
+#endif
+    return false;
+}
+
+bool
+pf_addr_test_dowork(const struct context *src, const struct mroute_addr *dest, const char *prefix)
+{
+    struct pf_set *pfs = src->c2.pf.pfs;
+    if (pfs && !pfs->kill)
+    {
+        const in_addr_t addr = in_addr_t_from_mroute_addr(dest);
+        const struct pf_subnet *se = pfs->sns.list;
+        while (se)
+        {
+            if ((addr & se->rule.netmask) == se->rule.network)
+            {
+#ifdef ENABLE_DEBUG
+                if (check_debug_level(D_PF_DEBUG))
+                {
+                    pf_addr_test_print("PF_ADDR_MATCH", prefix, src, dest, !se->rule.exclude, &se->rule);
+                }
+#endif
+                return !se->rule.exclude;
+            }
+            se = se->next;
+        }
+#ifdef ENABLE_DEBUG
+        if (check_debug_level(D_PF_DEBUG))
+        {
+            pf_addr_test_print("PF_ADDR_DEFAULT", prefix, src, dest, pfs->sns.default_allow, NULL);
+        }
+#endif
+        return pfs->sns.default_allow;
+    }
+    else
+    {
+#ifdef ENABLE_DEBUG
+        if (check_debug_level(D_PF_DEBUG))
+        {
+            pf_addr_test_print("PF_ADDR_FAULT", prefix, src, dest, false, NULL);
+        }
+#endif
+        return false;
+    }
+}
+
+#ifdef PLUGIN_PF
+void
+pf_check_reload(struct context *c)
+{
+    const int slow_wakeup = 15;
+    const int fast_wakeup = 1;
+    const int wakeup_transition = 60;
+    bool reloaded = false;
+
+    if (c->c2.pf.enabled
+        && c->c2.pf.filename
+        && event_timeout_trigger(&c->c2.pf.reload, &c->c2.timeval, ETT_DEFAULT))
+    {
+        platform_stat_t s;
+        if (!platform_stat(c->c2.pf.filename, &s))
+        {
+            if (s.st_mtime > c->c2.pf.file_last_mod)
+            {
+                struct pf_set *pfs = pf_init_from_file(c->c2.pf.filename);
+                if (pfs)
+                {
+                    if (c->c2.pf.pfs)
+                    {
+                        pf_destroy(c->c2.pf.pfs);
+                    }
+                    c->c2.pf.pfs = pfs;
+                    reloaded = true;
+                    if (pf_kill_test(pfs))
+                    {
+                        c->sig->signal_received = SIGTERM;
+                        c->sig->signal_text = "pf-kill";
+                    }
+                }
+                c->c2.pf.file_last_mod = s.st_mtime;
+            }
+        }
+        {
+            int wakeup = slow_wakeup;
+            if (!c->c2.pf.pfs && c->c2.pf.n_check_reload < wakeup_transition)
+            {
+                wakeup = fast_wakeup;
+            }
+            event_timeout_init(&c->c2.pf.reload, wakeup, now);
+            reset_coarse_timers(c);
+            c->c2.pf.n_check_reload++;
+        }
+    }
+#ifdef ENABLE_DEBUG
+    if (reloaded && check_debug_level(D_PF_DEBUG))
+    {
+        pf_context_print(&c->c2.pf, "pf_check_reload", D_PF_DEBUG);
+    }
+#endif
+}
+#endif /* ifdef PLUGIN_PF */
+
+#ifdef MANAGEMENT_PF
+bool
+pf_load_from_buffer_list(struct context *c, const struct buffer_list *config)
+{
+    struct pf_set *pfs = pf_init(config, "[SERVER-PF]", false);
+    if (pfs)
+    {
+        if (c->c2.pf.pfs)
+        {
+            pf_destroy(c->c2.pf.pfs);
+        }
+        c->c2.pf.pfs = pfs;
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+#endif
+
+void
+pf_init_context(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+#ifdef PLUGIN_PF
+    if (plugin_defined(c->plugins, OPENVPN_PLUGIN_ENABLE_PF))
+    {
+        const char *pf_file = create_temp_file(c->options.tmp_dir, "pf", &gc);
+        if (pf_file)
+        {
+            setenv_str(c->c2.es, "pf_file", pf_file);
+
+            if (plugin_call(c->plugins, OPENVPN_PLUGIN_ENABLE_PF, NULL, NULL, c->c2.es) == OPENVPN_PLUGIN_FUNC_SUCCESS)
+            {
+                event_timeout_init(&c->c2.pf.reload, 1, now);
+                c->c2.pf.filename = string_alloc(pf_file, &c->c2.gc);
+                c->c2.pf.enabled = true;
+#ifdef ENABLE_DEBUG
+                if (check_debug_level(D_PF_DEBUG))
+                {
+                    pf_context_print(&c->c2.pf, "pf_init_context#1", D_PF_DEBUG);
+                }
+#endif
+            }
+            else
+            {
+                msg(M_WARN, "WARNING: OPENVPN_PLUGIN_ENABLE_PF disabled");
+            }
+        }
+    }
+#endif /* ifdef PLUGIN_PF */
+#ifdef MANAGEMENT_PF
+    if (!c->c2.pf.enabled && management_enable_pf(management))
+    {
+        c->c2.pf.enabled = true;
+#ifdef ENABLE_DEBUG
+        if (check_debug_level(D_PF_DEBUG))
+        {
+            pf_context_print(&c->c2.pf, "pf_init_context#2", D_PF_DEBUG);
+        }
+#endif
+    }
+#endif
+    gc_free(&gc);
+}
+
+void
+pf_destroy_context(struct pf_context *pfc)
+{
+#ifdef PLUGIN_PF
+    if (pfc->filename)
+    {
+        platform_unlink(pfc->filename);
+    }
+#endif
+    if (pfc->pfs)
+    {
+        pf_destroy(pfc->pfs);
+    }
+}
+
+#ifdef ENABLE_DEBUG
+
+static void
+pf_subnet_set_print(const struct pf_subnet_set *s, const int lev)
+{
+    struct gc_arena gc = gc_new();
+    if (s)
+    {
+        struct pf_subnet *e;
+
+        msg(lev, "  ----- struct pf_subnet_set -----");
+        msg(lev, "  default_allow=%s", drop_accept(s->default_allow));
+
+        for (e = s->list; e != NULL; e = e->next)
+        {
+            msg(lev, "   %s/%s %s",
+                print_in_addr_t(e->rule.network, 0, &gc),
+                print_in_addr_t(e->rule.netmask, 0, &gc),
+                drop_accept(!e->rule.exclude));
+        }
+    }
+    gc_free(&gc);
+}
+
+static void
+pf_cn_set_print(const struct pf_cn_set *s, const int lev)
+{
+    if (s)
+    {
+        struct hash_iterator hi;
+        struct hash_element *he;
+
+        msg(lev, "  ----- struct pf_cn_set -----");
+        msg(lev, "  default_allow=%s", drop_accept(s->default_allow));
+
+        if (s->hash_table)
+        {
+            hash_iterator_init(s->hash_table, &hi);
+            while ((he = hash_iterator_next(&hi)))
+            {
+                struct pf_cn *e = (struct pf_cn *)he->value;
+                msg(lev, "   %s %s",
+                    e->cn,
+                    drop_accept(!e->exclude));
+            }
+
+            msg(lev, "  ----------");
+
+            {
+                struct pf_cn_elem *ce;
+                for (ce = s->list; ce != NULL; ce = ce->next)
+                {
+                    struct pf_cn *e = lookup_cn_rule(s->hash_table, ce->rule.cn, cn_hash_function(ce->rule.cn, 0));
+                    if (e)
+                    {
+                        msg(lev, "   %s %s",
+                            e->cn,
+                            drop_accept(!e->exclude));
+                    }
+                    else
+                    {
+                        msg(lev, "   %s LOOKUP FAILED", ce->rule.cn);
+                    }
+                }
+            }
+        }
+    }
+}
+
+static void
+pf_set_print(const struct pf_set *pfs, const int lev)
+{
+    if (pfs)
+    {
+        msg(lev, " ----- struct pf_set -----");
+        msg(lev, " kill=%d", pfs->kill);
+        pf_subnet_set_print(&pfs->sns, lev);
+        pf_cn_set_print(&pfs->cns, lev);
+    }
+}
+
+void
+pf_context_print(const struct pf_context *pfc, const char *prefix, const int lev)
+{
+    msg(lev, "----- %s : struct pf_context -----", prefix);
+    if (pfc)
+    {
+        msg(lev, "enabled=%d", pfc->enabled);
+#ifdef PLUGIN_PF
+        msg(lev, "filename='%s'", np(pfc->filename));
+        msg(lev, "file_last_mod=%u", (unsigned int)pfc->file_last_mod);
+        msg(lev, "n_check_reload=%u", pfc->n_check_reload);
+        msg(lev, "reload=[%d,%u,%u]", pfc->reload.defined, pfc->reload.n, (unsigned int)pfc->reload.last);
+#endif
+        pf_set_print(pfc->pfs, lev);
+    }
+    msg(lev, "--------------------");
+}
+
+#endif /* ifdef ENABLE_DEBUG */
+
+#endif /* if defined(ENABLE_PF) */
diff --git a/src/openvpn/pf.h b/src/openvpn/pf.h
new file mode 100644
index 0000000..ff75a00
--- /dev/null
+++ b/src/openvpn/pf.h
@@ -0,0 +1,104 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/* packet filter functions */
+
+#if defined(ENABLE_PF) && !defined(OPENVPN_PF_H)
+#define OPENVPN_PF_H
+
+#include "list.h"
+#include "mroute.h"
+
+#define PF_MAX_LINE_LEN 256
+
+struct context;
+
+struct ipv4_subnet {
+    bool exclude;
+    in_addr_t network;
+    in_addr_t netmask;
+};
+
+struct pf_subnet {
+    struct pf_subnet *next;
+    struct ipv4_subnet rule;
+};
+
+struct pf_subnet_set {
+    bool default_allow;
+    struct pf_subnet *list;
+};
+
+struct pf_cn {
+    bool exclude;
+    char *cn;
+};
+
+struct pf_cn_elem {
+    struct pf_cn_elem *next;
+    struct pf_cn rule;
+};
+
+struct pf_cn_set {
+    bool default_allow;
+    struct pf_cn_elem *list;
+    struct hash *hash_table;
+};
+
+struct pf_set {
+    bool kill;
+    struct pf_subnet_set sns;
+    struct pf_cn_set cns;
+};
+
+struct pf_context {
+    bool enabled;
+    struct pf_set *pfs;
+#ifdef PLUGIN_PF
+    char *filename;
+    time_t file_last_mod;
+    unsigned int n_check_reload;
+    struct event_timeout reload;
+#endif
+};
+
+void pf_init_context(struct context *c);
+
+void pf_destroy_context(struct pf_context *pfc);
+
+#ifdef PLUGIN_PF
+void pf_check_reload(struct context *c);
+
+#endif
+
+#ifdef MANAGEMENT_PF
+bool pf_load_from_buffer_list(struct context *c, const struct buffer_list *config);
+
+#endif
+
+#ifdef ENABLE_DEBUG
+void pf_context_print(const struct pf_context *pfc, const char *prefix, const int lev);
+
+#endif
+
+#endif /* if defined(ENABLE_PF) && !defined(OPENVPN_PF_H) */
diff --git a/src/openvpn/ping-inline.h b/src/openvpn/ping-inline.h
new file mode 100644
index 0000000..1a5c8bc
--- /dev/null
+++ b/src/openvpn/ping-inline.h
@@ -0,0 +1,64 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PING_INLINE_H
+#define PING_INLINE_H
+
+/*
+ * Should we exit or restart due to ping (or other authenticated packet)
+ * not received in n seconds?
+ */
+static inline void
+check_ping_restart(struct context *c)
+{
+    void check_ping_restart_dowork(struct context *c);
+
+    if (c->options.ping_rec_timeout
+        && event_timeout_trigger(&c->c2.ping_rec_interval,
+                                 &c->c2.timeval,
+                                 (!c->options.ping_timer_remote
+                                  || link_socket_actual_defined(&c->c1.link_socket_addr.actual))
+                                 ? ETT_DEFAULT : 15))
+    {
+        check_ping_restart_dowork(c);
+    }
+}
+
+/*
+ * Should we ping the remote?
+ */
+static inline void
+check_ping_send(struct context *c)
+{
+    void check_ping_send_dowork(struct context *c);
+
+    if (c->options.ping_send_timeout
+        && event_timeout_trigger(&c->c2.ping_send_interval,
+                                 &c->c2.timeval,
+                                 !TO_LINK_DEF(c) ? ETT_DEFAULT : 1))
+    {
+        check_ping_send_dowork(c);
+    }
+}
+
+#endif /* ifndef PING_INLINE_H */
diff --git a/src/openvpn/ping.c b/src/openvpn/ping.c
new file mode 100644
index 0000000..208170d
--- /dev/null
+++ b/src/openvpn/ping.c
@@ -0,0 +1,99 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "ping.h"
+
+#include "memdbg.h"
+
+#include "ping-inline.h"
+
+/*
+ * This random string identifies an OpenVPN ping packet.
+ * It should be of sufficient length and randomness
+ * so as not to collide with other tunnel data.
+ *
+ * PING_STRING_SIZE must be sizeof (ping_string)
+ */
+const uint8_t ping_string[] = {
+    0x2a, 0x18, 0x7b, 0xf3, 0x64, 0x1e, 0xb4, 0xcb,
+    0x07, 0xed, 0x2d, 0x0a, 0x98, 0x1f, 0xc7, 0x48
+};
+
+/*
+ * Should we exit or restart due to ping (or other authenticated packet)
+ * not received in n seconds?
+ */
+void
+check_ping_restart_dowork(struct context *c)
+{
+    struct gc_arena gc = gc_new();
+    switch (c->options.ping_rec_timeout_action)
+    {
+        case PING_EXIT:
+            msg(M_INFO, "%sInactivity timeout (--ping-exit), exiting",
+                format_common_name(c, &gc));
+            c->sig->signal_received = SIGTERM;
+            c->sig->signal_text = "ping-exit";
+            break;
+
+        case PING_RESTART:
+            msg(M_INFO, "%sInactivity timeout (--ping-restart), restarting",
+                format_common_name(c, &gc));
+            c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Ping Restart */
+            c->sig->signal_text = "ping-restart";
+            break;
+
+        default:
+            ASSERT(0);
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Should we ping the remote?
+ */
+void
+check_ping_send_dowork(struct context *c)
+{
+    c->c2.buf = c->c2.buffers->aux_buf;
+    ASSERT(buf_init(&c->c2.buf, FRAME_HEADROOM(&c->c2.frame)));
+    ASSERT(buf_safe(&c->c2.buf, MAX_RW_SIZE_TUN(&c->c2.frame)));
+    ASSERT(buf_write(&c->c2.buf, ping_string, sizeof(ping_string)));
+
+    /*
+     * We will treat the ping like any other outgoing packet,
+     * encrypt, sign, etc.
+     */
+    encrypt_sign(c, true);
+    /* Set length to 0, so it won't be counted as activity */
+    c->c2.buf.len = 0;
+    dmsg(D_PING, "SENT PING");
+}
diff --git a/src/openvpn/ping.h b/src/openvpn/ping.h
new file mode 100644
index 0000000..05793b4
--- /dev/null
+++ b/src/openvpn/ping.h
@@ -0,0 +1,46 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PING_H
+#define PING_H
+
+#include "init.h"
+#include "forward.h"
+
+/*
+ * Initial default --ping-restart before --pull
+ */
+#define PRE_PULL_INITIAL_PING_RESTART 120  /* in seconds */
+
+extern const uint8_t ping_string[];
+
+/* PING_STRING_SIZE must be sizeof (ping_string) */
+#define PING_STRING_SIZE 16
+
+static inline bool
+is_ping_msg(const struct buffer *buf)
+{
+    return buf_string_match(buf, ping_string, PING_STRING_SIZE);
+}
+
+#endif
diff --git a/src/openvpn/pkcs11.c b/src/openvpn/pkcs11.c
new file mode 100644
index 0000000..d40ca45
--- /dev/null
+++ b/src/openvpn/pkcs11.c
@@ -0,0 +1,1033 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_PKCS11)
+
+#include <pkcs11-helper-1.0/pkcs11h-certificate.h>
+#include "basic.h"
+#include "error.h"
+#include "manage.h"
+#include "base64.h"
+#include "pkcs11.h"
+#include "misc.h"
+#include "otime.h"
+#include "console.h"
+#include "pkcs11_backend.h"
+
+static
+time_t
+__mytime(void)
+{
+    return openvpn_time(NULL);
+}
+
+#if !defined(_WIN32)
+static
+int
+__mygettimeofday(struct timeval *tv)
+{
+    return gettimeofday(tv, NULL);
+}
+#endif
+
+static
+void
+__mysleep(const unsigned long usec)
+{
+#if defined(_WIN32)
+    Sleep(usec/1000);
+#else
+    usleep(usec);
+#endif
+}
+
+
+static pkcs11h_engine_system_t s_pkcs11h_sys_engine = {
+    malloc,
+    free,
+    __mytime,
+    __mysleep,
+#if defined(_WIN32)
+    NULL
+#else
+    __mygettimeofday
+#endif
+};
+
+static
+unsigned
+_pkcs11_msg_pkcs112openvpn(
+    const unsigned flags
+    )
+{
+    unsigned openvpn_flags;
+
+    switch (flags)
+    {
+        case PKCS11H_LOG_DEBUG2:
+            openvpn_flags = D_PKCS11_DEBUG;
+            break;
+
+        case PKCS11H_LOG_DEBUG1:
+            openvpn_flags = D_SHOW_PKCS11;
+            break;
+
+        case PKCS11H_LOG_INFO:
+            openvpn_flags = M_INFO;
+            break;
+
+        case PKCS11H_LOG_WARN:
+            openvpn_flags = M_WARN;
+            break;
+
+        case PKCS11H_LOG_ERROR:
+            openvpn_flags = M_FATAL;
+            break;
+
+        default:
+            openvpn_flags = M_FATAL;
+            break;
+    }
+
+#if defined(ENABLE_PKCS11_FORCE_DEBUG)
+    openvpn_flags = M_INFO;
+#endif
+
+    return openvpn_flags;
+}
+
+static
+unsigned
+_pkcs11_msg_openvpn2pkcs11(
+    const unsigned flags
+    )
+{
+    unsigned pkcs11_flags;
+
+    if ((flags & D_PKCS11_DEBUG) != 0)
+    {
+        pkcs11_flags = PKCS11H_LOG_DEBUG2;
+    }
+    else if ((flags & D_SHOW_PKCS11) != 0)
+    {
+        pkcs11_flags = PKCS11H_LOG_DEBUG1;
+    }
+    else if ((flags & M_INFO) != 0)
+    {
+        pkcs11_flags = PKCS11H_LOG_INFO;
+    }
+    else if ((flags & M_WARN) != 0)
+    {
+        pkcs11_flags = PKCS11H_LOG_WARN;
+    }
+    else if ((flags & M_FATAL) != 0)
+    {
+        pkcs11_flags = PKCS11H_LOG_ERROR;
+    }
+    else
+    {
+        pkcs11_flags = PKCS11H_LOG_ERROR;
+    }
+
+#if defined(ENABLE_PKCS11_FORCE_DEBUG)
+    pkcs11_flags = PKCS11H_LOG_DEBUG2;
+#endif
+
+    return pkcs11_flags;
+}
+
+static
+void
+_pkcs11_openvpn_log(
+    void *const global_data,
+    unsigned flags,
+    const char *const szFormat,
+    va_list args
+    )
+{
+    char Buffer[10*1024];
+
+    (void)global_data;
+
+    vsnprintf(Buffer, sizeof(Buffer), szFormat, args);
+    Buffer[sizeof(Buffer)-1] = 0;
+
+    msg(_pkcs11_msg_pkcs112openvpn(flags), "%s", Buffer);
+}
+
+static
+PKCS11H_BOOL
+_pkcs11_openvpn_token_prompt(
+    void *const global_data,
+    void *const user_data,
+    const pkcs11h_token_id_t token,
+    const unsigned retry
+    )
+{
+    struct user_pass token_resp;
+
+    (void)global_data;
+    (void)user_data;
+    (void)retry;
+
+    ASSERT(token!=NULL);
+
+    CLEAR(token_resp);
+    token_resp.defined = false;
+    token_resp.nocache = true;
+    openvpn_snprintf(
+        token_resp.username,
+        sizeof(token_resp.username),
+        "Please insert %s token",
+        token->label
+        );
+
+    if (
+        !get_user_pass(
+            &token_resp,
+            NULL,
+            "token-insertion-request",
+            GET_USER_PASS_MANAGEMENT|GET_USER_PASS_NEED_OK|GET_USER_PASS_NOFATAL
+            )
+        )
+    {
+        return false;
+    }
+    else
+    {
+        return strcmp(token_resp.password, "ok") == 0;
+    }
+}
+
+static
+PKCS11H_BOOL
+_pkcs11_openvpn_pin_prompt(
+    void *const global_data,
+    void *const user_data,
+    const pkcs11h_token_id_t token,
+    const unsigned retry,
+    char *const pin,
+    const size_t pin_max
+    )
+{
+    struct user_pass token_pass;
+    char prompt[1024];
+
+    (void)global_data;
+    (void)user_data;
+    (void)retry;
+
+    ASSERT(token!=NULL);
+
+    openvpn_snprintf(prompt, sizeof(prompt), "%s token", token->label);
+
+    token_pass.defined = false;
+    token_pass.nocache = true;
+
+    if (
+        !get_user_pass(
+            &token_pass,
+            NULL,
+            prompt,
+            GET_USER_PASS_MANAGEMENT|GET_USER_PASS_PASSWORD_ONLY|GET_USER_PASS_NOFATAL
+            )
+        )
+    {
+        return false;
+    }
+    else
+    {
+        strncpynt(pin, token_pass.password, pin_max);
+        purge_user_pass(&token_pass, true);
+
+        if (strlen(pin) == 0)
+        {
+            return false;
+        }
+        else
+        {
+            return true;
+        }
+    }
+}
+
+bool
+pkcs11_initialize(
+    const bool protected_auth,
+    const int nPINCachePeriod
+    )
+{
+    CK_RV rv = CKR_FUNCTION_FAILED;
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_initialize - entered"
+        );
+
+    if ((rv = pkcs11h_engine_setSystem(&s_pkcs11h_sys_engine)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot initialize system engine %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_initialize()) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot initialize %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setLogHook(_pkcs11_openvpn_log, NULL)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set hooks %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    pkcs11h_setLogLevel(_pkcs11_msg_openvpn2pkcs11(get_debug_level()));
+
+    if ((rv = pkcs11h_setForkMode(FALSE)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set fork mode %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setTokenPromptHook(_pkcs11_openvpn_token_prompt, NULL)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set hooks %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setPINPromptHook(_pkcs11_openvpn_pin_prompt, NULL)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set hooks %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setProtectedAuthentication(protected_auth)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set protected authentication mode %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setPINCachePeriod(nPINCachePeriod)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set Pcache period %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    rv = CKR_OK;
+
+cleanup:
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_initialize - return %ld-'%s'",
+        rv,
+        pkcs11h_getMessage(rv)
+        );
+
+    return rv == CKR_OK;
+}
+
+void
+pkcs11_terminate(void)
+{
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_terminate - entered"
+        );
+
+    pkcs11h_terminate();
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_terminate - return"
+        );
+}
+
+bool
+pkcs11_addProvider(
+    const char *const provider,
+    const bool protected_auth,
+    const unsigned private_mode,
+    const bool cert_private
+    )
+{
+    CK_RV rv = CKR_OK;
+
+    ASSERT(provider!=NULL);
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_addProvider - entered - provider='%s', private_mode=%08x",
+        provider,
+        private_mode
+        );
+
+    msg(
+        M_INFO,
+        "PKCS#11: Adding PKCS#11 provider '%s'",
+        provider
+        );
+
+    if (
+        (rv = pkcs11h_addProvider(
+             provider,
+             provider,
+             protected_auth,
+             private_mode,
+             PKCS11H_SLOTEVENT_METHOD_AUTO,
+             0,
+             cert_private
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot initialize provider '%s' %ld-'%s'", provider, rv, pkcs11h_getMessage(rv));
+    }
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_addProvider - return rv=%ld-'%s'",
+        rv,
+        pkcs11h_getMessage(rv)
+        );
+
+    return rv == CKR_OK;
+}
+
+int
+pkcs11_logout(void)
+{
+    return pkcs11h_logout() == CKR_OK;
+}
+
+int
+pkcs11_management_id_count(void)
+{
+    pkcs11h_certificate_id_list_t id_list = NULL;
+    pkcs11h_certificate_id_list_t t = NULL;
+    CK_RV rv = CKR_OK;
+    int count = 0;
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_management_id_count - entered"
+        );
+
+    if (
+        (rv = pkcs11h_certificate_enumCertificateIds(
+             PKCS11H_ENUM_METHOD_CACHE_EXIST,
+             NULL,
+             PKCS11H_PROMPT_MASK_ALLOW_ALL,
+             NULL,
+             &id_list
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate list %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    for (count = 0, t = id_list; t != NULL; t = t->next)
+    {
+        count++;
+    }
+
+cleanup:
+
+    if (id_list != NULL)
+    {
+        pkcs11h_certificate_freeCertificateIdList(id_list);
+        id_list = NULL;
+    }
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_management_id_count - return count=%d",
+        count
+        );
+
+    return count;
+}
+
+bool
+pkcs11_management_id_get(
+    const int index,
+    char **id,
+    char **base64
+    )
+{
+    pkcs11h_certificate_id_list_t id_list = NULL;
+    pkcs11h_certificate_id_list_t entry = NULL;
+#if 0 /* certificate_id seems to be unused -- JY */
+    pkcs11h_certificate_id_t certificate_id = NULL;
+#endif
+    pkcs11h_certificate_t certificate = NULL;
+    CK_RV rv = CKR_OK;
+    unsigned char *certificate_blob = NULL;
+    size_t certificate_blob_size = 0;
+    size_t max;
+    char *internal_id = NULL;
+    char *internal_base64 = NULL;
+    int count = 0;
+    bool success = false;
+
+    ASSERT(id!=NULL);
+    ASSERT(base64!=NULL);
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_management_id_get - entered index=%d",
+        index
+        );
+
+    *id = NULL;
+    *base64 = NULL;
+
+    if (
+        (rv = pkcs11h_certificate_enumCertificateIds(
+             PKCS11H_ENUM_METHOD_CACHE_EXIST,
+             NULL,
+             PKCS11H_PROMPT_MASK_ALLOW_ALL,
+             NULL,
+             &id_list
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate list %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    entry = id_list;
+    count = 0;
+    while (entry != NULL && count != index)
+    {
+        count++;
+        entry = entry->next;
+    }
+
+    if (entry == NULL)
+    {
+        dmsg(
+            D_PKCS11_DEBUG,
+            "PKCS#11: pkcs11_management_id_get - no certificate at index=%d",
+            index
+            );
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_serializeCertificateId(
+             NULL,
+             &max,
+             entry->certificate_id
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot serialize certificate id %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((internal_id = (char *)malloc(max)) == NULL)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot allocate memory");
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_serializeCertificateId(
+             internal_id,
+             &max,
+             entry->certificate_id
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot serialize certificate id %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_create(
+             entry->certificate_id,
+             NULL,
+             PKCS11H_PROMPT_MASK_ALLOW_ALL,
+             PKCS11H_PIN_CACHE_INFINITE,
+             &certificate
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_getCertificateBlob(
+             certificate,
+             NULL,
+             &certificate_blob_size
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate blob %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((certificate_blob = (unsigned char *)malloc(certificate_blob_size)) == NULL)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot allocate memory");
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_getCertificateBlob(
+             certificate,
+             certificate_blob,
+             &certificate_blob_size
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate blob %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (openvpn_base64_encode(certificate_blob, certificate_blob_size, &internal_base64) == -1)
+    {
+        msg(M_WARN, "PKCS#11: Cannot encode certificate");
+        goto cleanup;
+    }
+
+    *id = internal_id;
+    internal_id = NULL;
+    *base64 = internal_base64;
+    internal_base64 = NULL;
+    success = true;
+
+cleanup:
+
+    if (id_list != NULL)
+    {
+        pkcs11h_certificate_freeCertificateIdList(id_list);
+        id_list = NULL;
+    }
+
+    if (internal_id != NULL)
+    {
+        free(internal_id);
+        internal_id = NULL;
+    }
+
+    if (internal_base64 != NULL)
+    {
+        free(internal_base64);
+        internal_base64 = NULL;
+    }
+
+    if (certificate_blob != NULL)
+    {
+        free(certificate_blob);
+        certificate_blob = NULL;
+    }
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: pkcs11_management_id_get - return success=%d, id='%s'",
+        success ? 1 : 0,
+        *id
+        );
+
+    return success;
+}
+
+int
+tls_ctx_use_pkcs11(
+    struct tls_root_ctx *const ssl_ctx,
+    bool pkcs11_id_management,
+    const char *const pkcs11_id
+    )
+{
+    pkcs11h_certificate_id_t certificate_id = NULL;
+    pkcs11h_certificate_t certificate = NULL;
+    CK_RV rv = CKR_OK;
+
+    bool ok = false;
+
+    ASSERT(ssl_ctx!=NULL);
+    ASSERT(pkcs11_id_management || pkcs11_id!=NULL);
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: tls_ctx_use_pkcs11 - entered - ssl_ctx=%p, pkcs11_id_management=%d, pkcs11_id='%s'",
+        (void *)ssl_ctx,
+        pkcs11_id_management ? 1 : 0,
+        pkcs11_id
+        );
+
+    if (pkcs11_id_management)
+    {
+        struct user_pass id_resp;
+
+        CLEAR(id_resp);
+
+        id_resp.defined = false;
+        id_resp.nocache = true;
+        openvpn_snprintf(
+            id_resp.username,
+            sizeof(id_resp.username),
+            "Please specify PKCS#11 id to use"
+            );
+
+        if (
+            !get_user_pass(
+                &id_resp,
+                NULL,
+                "pkcs11-id-request",
+                GET_USER_PASS_MANAGEMENT|GET_USER_PASS_NEED_STR|GET_USER_PASS_NOFATAL
+                )
+            )
+        {
+            goto cleanup;
+        }
+
+        if (
+            (rv = pkcs11h_certificate_deserializeCertificateId(
+                 &certificate_id,
+                 id_resp.password
+                 )) != CKR_OK
+            )
+        {
+            msg(M_WARN, "PKCS#11: Cannot deserialize id %ld-'%s'", rv, pkcs11h_getMessage(rv));
+            goto cleanup;
+        }
+    }
+    else
+    {
+        if (
+            (rv = pkcs11h_certificate_deserializeCertificateId(
+                 &certificate_id,
+                 pkcs11_id
+                 )) != CKR_OK
+            )
+        {
+            msg(M_WARN, "PKCS#11: Cannot deserialize id %ld-'%s'", rv, pkcs11h_getMessage(rv));
+            goto cleanup;
+        }
+    }
+
+    if (
+        (rv = pkcs11h_certificate_create(
+             certificate_id,
+             NULL,
+             PKCS11H_PROMPT_MASK_ALLOW_ALL,
+             PKCS11H_PIN_CACHE_INFINITE,
+             &certificate
+             )) != CKR_OK
+        )
+    {
+        msg(M_WARN, "PKCS#11: Cannot get certificate %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (
+        (pkcs11_init_tls_session(
+             certificate,
+             ssl_ctx
+             ))
+        )
+    {
+        /* Handled by SSL context free */
+        certificate = NULL;
+        goto cleanup;
+    }
+
+    /* Handled by SSL context free */
+    certificate = NULL;
+    ok = true;
+
+cleanup:
+    if (certificate != NULL)
+    {
+        pkcs11h_certificate_freeCertificate(certificate);
+        certificate = NULL;
+    }
+
+    if (certificate_id != NULL)
+    {
+        pkcs11h_certificate_freeCertificateId(certificate_id);
+        certificate_id = NULL;
+    }
+
+    dmsg(
+        D_PKCS11_DEBUG,
+        "PKCS#11: tls_ctx_use_pkcs11 - return ok=%d, rv=%ld",
+        ok ? 1 : 0,
+        rv
+        );
+
+    return ok ? 1 : 0;
+}
+
+static
+PKCS11H_BOOL
+_pkcs11_openvpn_show_pkcs11_ids_pin_prompt(
+    void *const global_data,
+    void *const user_data,
+    const pkcs11h_token_id_t token,
+    const unsigned retry,
+    char *const pin,
+    const size_t pin_max
+    )
+{
+    struct gc_arena gc = gc_new();
+    struct buffer pass_prompt = alloc_buf_gc(128, &gc);
+
+    (void)global_data;
+    (void)user_data;
+    (void)retry;
+
+    ASSERT(token!=NULL);
+
+    buf_printf(&pass_prompt, "Please enter '%s' token PIN or 'cancel': ", token->display);
+    if (!query_user_SINGLE(BSTR(&pass_prompt), BLEN(&pass_prompt),
+                           pin, pin_max, false))
+    {
+        msg(M_FATAL, "Could not retrieve the PIN");
+    }
+
+    gc_free(&gc);
+
+    if (!strcmp(pin, "cancel"))
+    {
+        return FALSE;
+    }
+    else
+    {
+        return TRUE;
+    }
+}
+
+void
+show_pkcs11_ids(
+    const char *const provider,
+    bool cert_private
+    )
+{
+    struct gc_arena gc = gc_new();
+    pkcs11h_certificate_id_list_t user_certificates = NULL;
+    pkcs11h_certificate_id_list_t current = NULL;
+    CK_RV rv = CKR_FUNCTION_FAILED;
+
+    if ((rv = pkcs11h_initialize()) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot initialize %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setLogHook(_pkcs11_openvpn_log, NULL)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set hooks %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    pkcs11h_setLogLevel(_pkcs11_msg_openvpn2pkcs11(get_debug_level()));
+
+    if ((rv = pkcs11h_setProtectedAuthentication(TRUE)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set protected authentication %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if ((rv = pkcs11h_setPINPromptHook(_pkcs11_openvpn_show_pkcs11_ids_pin_prompt, NULL)) != CKR_OK)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot set PIN hook %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_addProvider(
+             provider,
+             provider,
+             TRUE,
+             0,
+             FALSE,
+             0,
+             cert_private ? TRUE : FALSE
+             )) != CKR_OK
+        )
+    {
+        msg(M_FATAL, "PKCS#11: Cannot add provider '%s' %ld-'%s'", provider, rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    if (
+        (rv = pkcs11h_certificate_enumCertificateIds(
+             PKCS11H_ENUM_METHOD_CACHE_EXIST,
+             NULL,
+             PKCS11H_PROMPT_MASK_ALLOW_ALL,
+             NULL,
+             &user_certificates
+             )) != CKR_OK
+        )
+    {
+        msg(M_FATAL, "PKCS#11: Cannot enumerate certificates %ld-'%s'", rv, pkcs11h_getMessage(rv));
+        goto cleanup;
+    }
+
+    msg(
+        M_INFO|M_NOPREFIX|M_NOLF,
+        (
+            "\n"
+            "The following objects are available for use.\n"
+            "Each object shown below may be used as parameter to\n"
+            "--pkcs11-id option please remember to use single quote mark.\n"
+        )
+        );
+    for (current = user_certificates; current != NULL; current = current->next)
+    {
+        pkcs11h_certificate_t certificate = NULL;
+        char *dn = NULL;
+        char serial[1024] = {0};
+        char *ser = NULL;
+        size_t ser_len = 0;
+
+        if (
+            (rv = pkcs11h_certificate_serializeCertificateId(
+                 NULL,
+                 &ser_len,
+                 current->certificate_id
+                 )) != CKR_OK
+            )
+        {
+            msg(M_FATAL, "PKCS#11: Cannot serialize certificate %ld-'%s'", rv, pkcs11h_getMessage(rv));
+            goto cleanup1;
+        }
+
+        if (
+            rv == CKR_OK
+            && (ser = (char *)malloc(ser_len)) == NULL
+            )
+        {
+            msg(M_FATAL, "PKCS#11: Cannot allocate memory");
+            goto cleanup1;
+        }
+
+        if (
+            (rv = pkcs11h_certificate_serializeCertificateId(
+                 ser,
+                 &ser_len,
+                 current->certificate_id
+                 )) != CKR_OK
+            )
+        {
+            msg(M_FATAL, "PKCS#11: Cannot serialize certificate %ld-'%s'", rv, pkcs11h_getMessage(rv));
+            goto cleanup1;
+        }
+
+        if (
+            (rv = pkcs11h_certificate_create(
+                 current->certificate_id,
+                 NULL,
+                 PKCS11H_PROMPT_MASK_ALLOW_ALL,
+                 PKCS11H_PIN_CACHE_INFINITE,
+                 &certificate
+                 ))
+            )
+        {
+            msg(M_FATAL, "PKCS#11: Cannot create certificate %ld-'%s'", rv, pkcs11h_getMessage(rv));
+            goto cleanup1;
+        }
+
+        if (
+            (dn = pkcs11_certificate_dn(
+                 certificate,
+                 &gc
+                 )) == NULL
+            )
+        {
+            goto cleanup1;
+        }
+
+        if (
+            (pkcs11_certificate_serial(
+                 certificate,
+                 serial,
+                 sizeof(serial)
+                 ))
+            )
+        {
+            goto cleanup1;
+        }
+
+        msg(
+            M_INFO|M_NOPREFIX|M_NOLF,
+            (
+                "\n"
+                "Certificate\n"
+                "       DN:             %s\n"
+                "       Serial:         %s\n"
+                "       Serialized id:  %s\n"
+            ),
+            dn,
+            serial,
+            ser
+            );
+
+cleanup1:
+
+        if (certificate != NULL)
+        {
+            pkcs11h_certificate_freeCertificate(certificate);
+            certificate = NULL;
+        }
+
+        if (ser != NULL)
+        {
+            free(ser);
+            ser = NULL;
+        }
+    }
+
+cleanup:
+    if (user_certificates != NULL)
+    {
+        pkcs11h_certificate_freeCertificateIdList(user_certificates);
+        user_certificates = NULL;
+    }
+
+    pkcs11h_terminate();
+    gc_free(&gc);
+}
+
+#else  /* if defined(ENABLE_PKCS11) */
+#ifdef _MSC_VER  /* Dummy function needed to avoid empty file compiler warning in Microsoft VC */
+static void
+dummy(void)
+{
+}
+#endif
+#endif /* ENABLE_PKCS11 */
diff --git a/src/openvpn/pkcs11.h b/src/openvpn/pkcs11.h
new file mode 100644
index 0000000..66c6a7e
--- /dev/null
+++ b/src/openvpn/pkcs11.h
@@ -0,0 +1,76 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef OPENVPN_PKCS11_H
+#define OPENVPN_PKCS11_H
+
+#if defined(ENABLE_PKCS11)
+
+#include "ssl_common.h"
+
+bool
+pkcs11_initialize(
+    const bool fProtectedAuthentication,
+    const int nPINCachePeriod
+    );
+
+void
+pkcs11_terminate();
+
+bool
+pkcs11_addProvider(
+    const char *const provider,
+    const bool fProtectedAuthentication,
+    const unsigned private_mode,
+    const bool fCertIsPrivate
+    );
+
+int
+pkcs11_logout();
+
+int
+pkcs11_management_id_count();
+
+bool
+pkcs11_management_id_get(
+    const int index,
+    char **id,
+    char **base64
+    );
+
+int
+tls_ctx_use_pkcs11(
+    struct tls_root_ctx *const ssl_ctx,
+    bool pkcs11_id_management,
+    const char *const pkcs11_id
+    );
+
+void
+show_pkcs11_ids(
+    const char *const provider,
+    bool cert_private
+    );
+
+#endif                  /* ENABLE_PKCS11 */
+
+#endif                  /* OPENVPN_PKCS11H_H */
diff --git a/src/openvpn/pkcs11_backend.h b/src/openvpn/pkcs11_backend.h
new file mode 100644
index 0000000..e8fb664
--- /dev/null
+++ b/src/openvpn/pkcs11_backend.h
@@ -0,0 +1,74 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file PKCS #11 SSL library-specific backend
+ */
+
+#ifndef PKCS11_BACKEND_H_
+#define PKCS11_BACKEND_H_
+
+#include "syshead.h"
+
+#if defined(ENABLE_PKCS11)
+
+#include "ssl_common.h"
+
+#include <pkcs11-helper-1.0/pkcs11h-certificate.h>
+
+/**
+ * Retrieve PKCS #11 Certificate's DN in a printable format.
+ *
+ * @param certificate   The PKCS #11 helper certificate object
+ * @param gc            Garbage collection pool to allocate memory in
+ *
+ * @return              Certificate's DN on success, NULL on failure
+ */
+char *pkcs11_certificate_dn(pkcs11h_certificate_t certificate, struct gc_arena *gc);
+
+/**
+ * Retrieve PKCS #11 Certificate's serial number in a printable format.
+ *
+ * @param certificate   The PKCS #11 helper certificate object
+ * @param serial        Buffer that the certificate's serial will be placed in.
+ * @param serial_len    Size of said buffer.
+ *
+ * @return              1 on failure, 0 on success
+ */
+int pkcs11_certificate_serial(pkcs11h_certificate_t certificate, char *serial,
+                              size_t serial_len);
+
+/**
+ * Load PKCS #11 Certificate's information into the given TLS context
+ *
+ * @param certificate   The PKCS #11 helper certificate object
+ * @param ssl_ctx       TLS context to use.
+ *
+ * @return              1 on failure, 0 on success
+ */
+int pkcs11_init_tls_session(pkcs11h_certificate_t certificate,
+                            struct tls_root_ctx *const ssl_ctx);
+
+#endif /* defined(ENABLE_PKCS11) */
+#endif /* PKCS11_BACKEND_H_ */
diff --git a/src/openvpn/pkcs11_mbedtls.c b/src/openvpn/pkcs11_mbedtls.c
new file mode 100644
index 0000000..7620624
--- /dev/null
+++ b/src/openvpn/pkcs11_mbedtls.c
@@ -0,0 +1,132 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file PKCS #11 mbed TLS backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_PKCS11) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "errlevel.h"
+#include "pkcs11_backend.h"
+#include "ssl_verify_backend.h"
+#include <mbedtls/pkcs11.h>
+#include <mbedtls/x509.h>
+
+int
+pkcs11_init_tls_session(pkcs11h_certificate_t certificate,
+                        struct tls_root_ctx *const ssl_ctx)
+{
+    int ret = 1;
+
+    ASSERT(NULL != ssl_ctx);
+
+    ALLOC_OBJ_CLEAR(ssl_ctx->crt_chain, mbedtls_x509_crt);
+    if (mbedtls_pkcs11_x509_cert_bind(ssl_ctx->crt_chain, certificate))
+    {
+        msg(M_FATAL, "PKCS#11: Cannot retrieve mbed TLS certificate object");
+        goto cleanup;
+    }
+
+    ALLOC_OBJ_CLEAR(ssl_ctx->priv_key_pkcs11, mbedtls_pkcs11_context);
+    if (mbedtls_pkcs11_priv_key_bind(ssl_ctx->priv_key_pkcs11, certificate))
+    {
+        msg(M_FATAL, "PKCS#11: Cannot initialize mbed TLS private key object");
+        goto cleanup;
+    }
+
+    ALLOC_OBJ_CLEAR(ssl_ctx->priv_key, mbedtls_pk_context);
+    if (!mbed_ok(mbedtls_pk_setup_rsa_alt(ssl_ctx->priv_key,
+                                          ssl_ctx->priv_key_pkcs11, mbedtls_ssl_pkcs11_decrypt,
+                                          mbedtls_ssl_pkcs11_sign, mbedtls_ssl_pkcs11_key_len)))
+    {
+        goto cleanup;
+    }
+
+    ret = 0;
+
+cleanup:
+    return ret;
+}
+
+char *
+pkcs11_certificate_dn(pkcs11h_certificate_t cert, struct gc_arena *gc)
+{
+    char *ret = NULL;
+    mbedtls_x509_crt mbed_crt = {0};
+
+    if (mbedtls_pkcs11_x509_cert_bind(&mbed_crt, cert))
+    {
+        msg(M_FATAL, "PKCS#11: Cannot retrieve mbed TLS certificate object");
+        goto cleanup;
+    }
+
+    if (!(ret = x509_get_subject(&mbed_crt, gc)))
+    {
+        msg(M_FATAL, "PKCS#11: mbed TLS cannot parse subject");
+        goto cleanup;
+    }
+
+cleanup:
+    mbedtls_x509_crt_free(&mbed_crt);
+
+    return ret;
+}
+
+int
+pkcs11_certificate_serial(pkcs11h_certificate_t cert, char *serial,
+                          size_t serial_len)
+{
+    int ret = 1;
+
+    mbedtls_x509_crt mbed_crt = {0};
+
+    if (mbedtls_pkcs11_x509_cert_bind(&mbed_crt, cert))
+    {
+        msg(M_FATAL, "PKCS#11: Cannot retrieve mbed TLS certificate object");
+        goto cleanup;
+    }
+
+    if (-1 == mbedtls_x509_serial_gets(serial, serial_len, &mbed_crt.serial))
+    {
+        msg(M_FATAL, "PKCS#11: mbed TLS cannot parse serial");
+        goto cleanup;
+    }
+
+    ret = 0;
+
+cleanup:
+    mbedtls_x509_crt_free(&mbed_crt);
+
+    return ret;
+}
+#endif /* defined(ENABLE_PKCS11) && defined(ENABLE_CRYPTO_MBEDTLS) */
diff --git a/src/openvpn/pkcs11_openssl.c b/src/openvpn/pkcs11_openssl.c
new file mode 100644
index 0000000..642769c
--- /dev/null
+++ b/src/openvpn/pkcs11_openssl.c
@@ -0,0 +1,194 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file PKCS #11 OpenSSL backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_PKCS11) && defined(ENABLE_CRYPTO_OPENSSL)
+
+#include "errlevel.h"
+#include "pkcs11_backend.h"
+#include "ssl_verify.h"
+#include <pkcs11-helper-1.0/pkcs11h-openssl.h>
+
+int
+pkcs11_init_tls_session(pkcs11h_certificate_t certificate,
+                        struct tls_root_ctx *const ssl_ctx)
+{
+    int ret = 1;
+
+    X509 *x509 = NULL;
+    EVP_PKEY *evp = NULL;
+    pkcs11h_openssl_session_t openssl_session = NULL;
+
+    if ((openssl_session = pkcs11h_openssl_createSession(certificate)) == NULL)
+    {
+        msg(M_WARN, "PKCS#11: Cannot initialize openssl session");
+        goto cleanup;
+    }
+
+    /*
+     * Will be released by openssl_session
+     */
+    certificate = NULL;
+
+    if ((evp = pkcs11h_openssl_session_getEVP(openssl_session)) == NULL)
+    {
+        msg(M_WARN, "PKCS#11: Unable get evp object");
+        goto cleanup;
+    }
+
+    if ((x509 = pkcs11h_openssl_session_getX509(openssl_session)) == NULL)
+    {
+        msg(M_WARN, "PKCS#11: Unable get certificate object");
+        goto cleanup;
+    }
+
+    if (!SSL_CTX_use_PrivateKey(ssl_ctx->ctx, evp))
+    {
+        msg(M_WARN, "PKCS#11: Cannot set private key for openssl");
+        goto cleanup;
+    }
+
+    if (!SSL_CTX_use_certificate(ssl_ctx->ctx, x509))
+    {
+        msg(M_WARN, "PKCS#11: Cannot set certificate for openssl");
+        goto cleanup;
+    }
+    ret = 0;
+
+cleanup:
+    /*
+     * Certificate freeing is usually handled by openssl_session.
+     * If something went wrong, creating the session we have to do it manually.
+     */
+    if (certificate != NULL)
+    {
+        pkcs11h_certificate_freeCertificate(certificate);
+        certificate = NULL;
+    }
+
+    /*
+     * openssl objects have reference
+     * count, so release them
+     */
+    if (x509 != NULL)
+    {
+        X509_free(x509);
+        x509 = NULL;
+    }
+
+    if (evp != NULL)
+    {
+        EVP_PKEY_free(evp);
+        evp = NULL;
+    }
+
+    if (openssl_session != NULL)
+    {
+        pkcs11h_openssl_freeSession(openssl_session);
+        openssl_session = NULL;
+    }
+    return ret;
+}
+
+char *
+pkcs11_certificate_dn(pkcs11h_certificate_t certificate, struct gc_arena *gc)
+{
+    X509 *x509 = NULL;
+
+    char *dn = NULL;
+
+    if ((x509 = pkcs11h_openssl_getX509(certificate)) == NULL)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot get X509");
+        goto cleanup;
+    }
+
+    dn = x509_get_subject(x509, gc);
+
+cleanup:
+    if (x509 != NULL)
+    {
+        X509_free(x509);
+        x509 = NULL;
+    }
+
+    return dn;
+}
+
+int
+pkcs11_certificate_serial(pkcs11h_certificate_t certificate, char *serial,
+                          size_t serial_len)
+{
+    X509 *x509 = NULL;
+    BIO *bio = NULL;
+    int ret = 1;
+    int n;
+
+    if ((x509 = pkcs11h_openssl_getX509(certificate)) == NULL)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot get X509");
+        goto cleanup;
+    }
+
+    if ((bio = BIO_new(BIO_s_mem())) == NULL)
+    {
+        msg(M_FATAL, "PKCS#11: Cannot create BIO");
+        goto cleanup;
+    }
+
+    i2a_ASN1_INTEGER(bio, X509_get_serialNumber(x509));
+    n = BIO_read(bio, serial, serial_len-1);
+
+    if (n<0)
+    {
+        serial[0] = '\x0';
+    }
+    else
+    {
+        serial[n] = 0;
+    }
+
+    ret = 0;
+
+cleanup:
+
+    if (x509 != NULL)
+    {
+        X509_free(x509);
+        x509 = NULL;
+    }
+    return ret;
+}
+#endif /* defined(ENABLE_PKCS11) && defined(ENABLE_OPENSSL) */
diff --git a/src/openvpn/platform.c b/src/openvpn/platform.c
new file mode 100644
index 0000000..fbffd0f
--- /dev/null
+++ b/src/openvpn/platform.c
@@ -0,0 +1,337 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "win32.h"
+
+#include "memdbg.h"
+
+#include "platform.h"
+
+/* Redefine the top level directory of the filesystem
+ * to restrict access to files for security */
+void
+platform_chroot(const char *path)
+{
+    if (path)
+    {
+#ifdef HAVE_CHROOT
+        const char *top = "/";
+        if (chroot(path))
+        {
+            msg(M_ERR, "chroot to '%s' failed", path);
+        }
+        if (platform_chdir(top))
+        {
+            msg(M_ERR, "cd to '%s' failed", top);
+        }
+        msg(M_INFO, "chroot to '%s' and cd to '%s' succeeded", path, top);
+#else  /* ifdef HAVE_CHROOT */
+        msg(M_FATAL, "Sorry but I can't chroot to '%s' because this operating system doesn't appear to support the chroot() system call", path);
+#endif
+    }
+}
+
+/* Get/Set UID of process */
+
+bool
+platform_user_get(const char *username, struct platform_state_user *state)
+{
+    bool ret = false;
+    CLEAR(*state);
+    if (username)
+    {
+#if defined(HAVE_GETPWNAM) && defined(HAVE_SETUID)
+        state->pw = getpwnam(username);
+        if (!state->pw)
+        {
+            msg(M_ERR, "failed to find UID for user %s", username);
+        }
+        state->username = username;
+        ret = true;
+#else  /* if defined(HAVE_GETPWNAM) && defined(HAVE_SETUID) */
+        msg(M_FATAL, "cannot get UID for user %s -- platform lacks getpwname() or setuid() system calls", username);
+#endif
+    }
+    return ret;
+}
+
+void
+platform_user_set(const struct platform_state_user *state)
+{
+#if defined(HAVE_GETPWNAM) && defined(HAVE_SETUID)
+    if (state->username && state->pw)
+    {
+        if (setuid(state->pw->pw_uid))
+        {
+            msg(M_ERR, "setuid('%s') failed", state->username);
+        }
+        msg(M_INFO, "UID set to %s", state->username);
+    }
+#endif
+}
+
+/* Get/Set GID of process */
+
+bool
+platform_group_get(const char *groupname, struct platform_state_group *state)
+{
+    bool ret = false;
+    CLEAR(*state);
+    if (groupname)
+    {
+#if defined(HAVE_GETGRNAM) && defined(HAVE_SETGID)
+        state->gr = getgrnam(groupname);
+        if (!state->gr)
+        {
+            msg(M_ERR, "failed to find GID for group %s", groupname);
+        }
+        state->groupname = groupname;
+        ret = true;
+#else  /* if defined(HAVE_GETGRNAM) && defined(HAVE_SETGID) */
+        msg(M_FATAL, "cannot get GID for group %s -- platform lacks getgrnam() or setgid() system calls", groupname);
+#endif
+    }
+    return ret;
+}
+
+void
+platform_group_set(const struct platform_state_group *state)
+{
+#if defined(HAVE_GETGRNAM) && defined(HAVE_SETGID)
+    if (state->groupname && state->gr)
+    {
+        if (setgid(state->gr->gr_gid))
+        {
+            msg(M_ERR, "setgid('%s') failed", state->groupname);
+        }
+        msg(M_INFO, "GID set to %s", state->groupname);
+#ifdef HAVE_SETGROUPS
+        {
+            gid_t gr_list[1];
+            gr_list[0] = state->gr->gr_gid;
+            if (setgroups(1, gr_list))
+            {
+                msg(M_ERR, "setgroups('%s') failed", state->groupname);
+            }
+        }
+#endif
+    }
+#endif
+}
+
+/* Change process priority */
+void
+platform_nice(int niceval)
+{
+    if (niceval)
+    {
+#ifdef HAVE_NICE
+        errno = 0;
+        if (nice(niceval) < 0 && errno != 0)
+        {
+            msg(M_WARN | M_ERRNO, "WARNING: nice %d failed", niceval);
+        }
+        else
+        {
+            msg(M_INFO, "nice %d succeeded", niceval);
+        }
+#else  /* ifdef HAVE_NICE */
+        msg(M_WARN, "WARNING: nice %d failed (function not implemented)", niceval);
+#endif
+    }
+}
+
+/* Get current PID */
+unsigned int
+platform_getpid(void)
+{
+#ifdef _WIN32
+    return (unsigned int) GetCurrentProcessId();
+#else
+#ifdef HAVE_GETPID
+    return (unsigned int) getpid();
+#else
+    return 0;
+#endif
+#endif
+}
+
+/* Disable paging */
+void
+platform_mlockall(bool print_msg)
+{
+#ifdef HAVE_MLOCKALL
+    if (mlockall(MCL_CURRENT | MCL_FUTURE))
+    {
+        msg(M_WARN | M_ERRNO, "WARNING: mlockall call failed");
+    }
+    else if (print_msg)
+    {
+        msg(M_INFO, "mlockall call succeeded");
+    }
+#else  /* ifdef HAVE_MLOCKALL */
+    msg(M_WARN, "WARNING: mlockall call failed (function not implemented)");
+#endif
+}
+
+/*
+ * Wrapper for chdir library function
+ */
+int
+platform_chdir(const char *dir)
+{
+#ifdef HAVE_CHDIR
+#ifdef _WIN32
+    int res;
+    struct gc_arena gc = gc_new();
+    res = _wchdir(wide_string(dir, &gc));
+    gc_free(&gc);
+    return res;
+#else  /* ifdef _WIN32 */
+    return chdir(dir);
+#endif
+#else  /* ifdef HAVE_CHDIR */
+    return -1;
+#endif
+}
+
+/*
+ * convert execve() return into a success/failure value
+ */
+bool
+platform_system_ok(int stat)
+{
+#ifdef _WIN32
+    return stat == 0;
+#else
+    return stat != -1 && WIFEXITED(stat) && WEXITSTATUS(stat) == 0;
+#endif
+}
+
+int
+platform_access(const char *path, int mode)
+{
+#ifdef _WIN32
+    struct gc_arena gc = gc_new();
+    int ret = _waccess(wide_string(path, &gc), mode & ~X_OK);
+    gc_free(&gc);
+    return ret;
+#else
+    return access(path, mode);
+#endif
+}
+
+/*
+ * Go to sleep for n milliseconds.
+ */
+void
+platform_sleep_milliseconds(unsigned int n)
+{
+#ifdef _WIN32
+    Sleep(n);
+#else
+    struct timeval tv;
+    tv.tv_sec = n / 1000;
+    tv.tv_usec = (n % 1000) * 1000;
+    select(0, NULL, NULL, NULL, &tv);
+#endif
+}
+
+/*
+ * Go to sleep indefinitely.
+ */
+void
+platform_sleep_until_signal(void)
+{
+#ifdef _WIN32
+    ASSERT(0);
+#else
+    select(0, NULL, NULL, NULL, NULL);
+#endif
+}
+
+/* delete a file, return true if succeeded */
+bool
+platform_unlink(const char *filename)
+{
+#if defined(_WIN32)
+    struct gc_arena gc = gc_new();
+    BOOL ret = DeleteFileW(wide_string(filename, &gc));
+    gc_free(&gc);
+    return (ret != 0);
+#elif defined(HAVE_UNLINK)
+    return (unlink(filename) == 0);
+#else  /* if defined(_WIN32) */
+    return false;
+#endif
+}
+
+FILE *
+platform_fopen(const char *path, const char *mode)
+{
+#ifdef _WIN32
+    struct gc_arena gc = gc_new();
+    FILE *f = _wfopen(wide_string(path, &gc), wide_string(mode, &gc));
+    gc_free(&gc);
+    return f;
+#else
+    return fopen(path, mode);
+#endif
+}
+
+int
+platform_open(const char *path, int flags, int mode)
+{
+#ifdef _WIN32
+    struct gc_arena gc = gc_new();
+    int fd = _wopen(wide_string(path, &gc), flags, mode);
+    gc_free(&gc);
+    return fd;
+#else
+    return open(path, flags, mode);
+#endif
+}
+
+int
+platform_stat(const char *path, platform_stat_t *buf)
+{
+#ifdef _WIN32
+    struct gc_arena gc = gc_new();
+    int res = _wstat(wide_string(path, &gc), buf);
+    gc_free(&gc);
+    return res;
+#else
+    return stat(path, buf);
+#endif
+}
+
diff --git a/src/openvpn/platform.h b/src/openvpn/platform.h
new file mode 100644
index 0000000..288937d
--- /dev/null
+++ b/src/openvpn/platform.h
@@ -0,0 +1,146 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PLATFORM_H
+#define PLATFORM_H
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef HAVE_PWD_H
+#include <pwd.h>
+#endif
+
+#ifdef HAVE_GRP_H
+#include <grp.h>
+#endif
+
+#ifdef HAVE_STDIO_H
+#include <stdio.h>
+#endif
+
+#include "basic.h"
+
+/* Get/Set UID of process */
+
+struct platform_state_user {
+#if defined(HAVE_GETPWNAM) && defined(HAVE_SETUID)
+    const char *username;
+    struct passwd *pw;
+#else
+    int dummy;
+#endif
+};
+
+/* Get/Set GID of process */
+
+struct platform_state_group {
+#if defined(HAVE_GETGRNAM) && defined(HAVE_SETGID)
+    const char *groupname;
+    struct group *gr;
+#else
+    int dummy;
+#endif
+};
+
+bool platform_user_get(const char *username, struct platform_state_user *state);
+
+void platform_user_set(const struct platform_state_user *state);
+
+bool platform_group_get(const char *groupname, struct platform_state_group *state);
+
+void platform_group_set(const struct platform_state_group *state);
+
+/*
+ * Extract UID or GID
+ */
+
+static inline int
+platform_state_user_uid(const struct platform_state_user *s)
+{
+#if defined(HAVE_GETPWNAM) && defined(HAVE_SETUID)
+    if (s->pw)
+    {
+        return s->pw->pw_uid;
+    }
+#endif
+    return -1;
+}
+
+static inline int
+platform_state_group_gid(const struct platform_state_group *s)
+{
+#if defined(HAVE_GETGRNAM) && defined(HAVE_SETGID)
+    if (s->gr)
+    {
+        return s->gr->gr_gid;
+    }
+#endif
+    return -1;
+}
+
+void platform_chroot(const char *path);
+
+void platform_nice(int niceval);
+
+unsigned int platform_getpid(void);
+
+void platform_mlockall(bool print_msg);  /* Disable paging */
+
+int platform_chdir(const char *dir);
+
+/* interpret the status code returned by execve() */
+bool platform_system_ok(int stat);
+
+int platform_access(const char *path, int mode);
+
+void platform_sleep_milliseconds(unsigned int n);
+
+void platform_sleep_until_signal(void);
+
+/* delete a file, return true if succeeded */
+bool platform_unlink(const char *filename);
+
+int platform_putenv(char *string);
+
+FILE *platform_fopen(const char *path, const char *mode);
+
+int platform_open(const char *path, int flags, int mode);
+
+#ifdef _WIN32
+typedef struct _stat platform_stat_t;
+#else
+typedef struct stat platform_stat_t;
+#endif
+int platform_stat(const char *path, platform_stat_t *buf);
+
+#endif /* ifndef PLATFORM_H */
diff --git a/src/openvpn/plugin.c b/src/openvpn/plugin.c
new file mode 100644
index 0000000..0ab99ab
--- /dev/null
+++ b/src/openvpn/plugin.c
@@ -0,0 +1,1028 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+#ifdef HAVE_CONFIG_VERSION_H
+#include "config-version.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_PLUGIN
+
+#ifdef HAVE_DLFCN_H
+#include <dlfcn.h>
+#endif
+
+#include "buffer.h"
+#include "error.h"
+#include "misc.h"
+#include "plugin.h"
+#include "ssl_backend.h"
+#include "base64.h"
+#include "win32.h"
+#include "memdbg.h"
+
+#define PLUGIN_SYMBOL_REQUIRED (1<<0)
+
+/* used only for program aborts */
+static struct plugin_common *static_plugin_common = NULL; /* GLOBAL */
+
+static void
+plugin_show_string_array(int msglevel, const char *name, const char *array[])
+{
+    int i;
+    for (i = 0; array[i]; ++i)
+    {
+        if (env_safe_to_print(array[i]))
+        {
+            msg(msglevel, "%s[%d] = '%s'", name, i, array[i]);
+        }
+    }
+}
+
+static void
+plugin_show_args_env(int msglevel, const char *argv[], const char *envp[])
+{
+    if (check_debug_level(msglevel))
+    {
+        plugin_show_string_array(msglevel, "ARGV", argv);
+        plugin_show_string_array(msglevel, "ENVP", envp);
+    }
+}
+
+static const char *
+plugin_type_name(const int type)
+{
+    switch (type)
+    {
+        case OPENVPN_PLUGIN_UP:
+            return "PLUGIN_UP";
+
+        case OPENVPN_PLUGIN_DOWN:
+            return "PLUGIN_DOWN";
+
+        case OPENVPN_PLUGIN_ROUTE_UP:
+            return "PLUGIN_ROUTE_UP";
+
+        case OPENVPN_PLUGIN_IPCHANGE:
+            return "PLUGIN_IPCHANGE";
+
+        case OPENVPN_PLUGIN_TLS_VERIFY:
+            return "PLUGIN_TLS_VERIFY";
+
+        case OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY:
+            return "PLUGIN_AUTH_USER_PASS_VERIFY";
+
+        case OPENVPN_PLUGIN_CLIENT_CONNECT:
+            return "PLUGIN_CLIENT_CONNECT";
+
+        case OPENVPN_PLUGIN_CLIENT_CONNECT_V2:
+            return "PLUGIN_CLIENT_CONNECT";
+
+        case OPENVPN_PLUGIN_CLIENT_DISCONNECT:
+            return "PLUGIN_CLIENT_DISCONNECT";
+
+        case OPENVPN_PLUGIN_LEARN_ADDRESS:
+            return "PLUGIN_LEARN_ADDRESS";
+
+        case OPENVPN_PLUGIN_TLS_FINAL:
+            return "PLUGIN_TLS_FINAL";
+
+        case OPENVPN_PLUGIN_ENABLE_PF:
+            return "PLUGIN_ENABLE_PF";
+
+        case OPENVPN_PLUGIN_ROUTE_PREDOWN:
+            return "PLUGIN_ROUTE_PREDOWN";
+
+        default:
+            return "PLUGIN_???";
+    }
+}
+
+static const char *
+plugin_mask_string(const unsigned int type_mask, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    bool first = true;
+    int i;
+
+    for (i = 0; i < OPENVPN_PLUGIN_N; ++i)
+    {
+        if (OPENVPN_PLUGIN_MASK(i) & type_mask)
+        {
+            if (!first)
+            {
+                buf_printf(&out, "|");
+            }
+            buf_printf(&out, "%s", plugin_type_name(i));
+            first = false;
+        }
+    }
+    return BSTR(&out);
+}
+
+static inline unsigned int
+plugin_supported_types(void)
+{
+    return ((1<<OPENVPN_PLUGIN_N)-1);
+}
+
+struct plugin_option_list *
+plugin_option_list_new(struct gc_arena *gc)
+{
+    struct plugin_option_list *ret;
+    ALLOC_OBJ_CLEAR_GC(ret, struct plugin_option_list, gc);
+    return ret;
+}
+
+bool
+plugin_option_list_add(struct plugin_option_list *list, char **p, struct gc_arena *gc)
+{
+    if (list->n < MAX_PLUGINS)
+    {
+        struct plugin_option *o = &list->plugins[list->n++];
+        o->argv = make_extended_arg_array(p, gc);
+        if (o->argv[0])
+        {
+            o->so_pathname = o->argv[0];
+        }
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+#ifndef ENABLE_SMALL
+void
+plugin_option_list_print(const struct plugin_option_list *list, int msglevel)
+{
+    int i;
+    struct gc_arena gc = gc_new();
+
+    for (i = 0; i < list->n; ++i)
+    {
+        const struct plugin_option *o = &list->plugins[i];
+        msg(msglevel, "  plugin[%d] %s '%s'", i, o->so_pathname, print_argv(o->argv, &gc, PA_BRACKET));
+    }
+
+    gc_free(&gc);
+}
+#endif
+
+#ifndef _WIN32
+
+static void
+libdl_resolve_symbol(void *handle, void **dest, const char *symbol, const char *plugin_name, const unsigned int flags)
+{
+    *dest = dlsym(handle, symbol);
+    if ((flags & PLUGIN_SYMBOL_REQUIRED) && !*dest)
+    {
+        msg(M_FATAL, "PLUGIN: could not find required symbol '%s' in plugin shared object %s: %s", symbol, plugin_name, dlerror());
+    }
+}
+
+#else  /* ifndef _WIN32 */
+
+static void
+dll_resolve_symbol(HMODULE module, void **dest, const char *symbol, const char *plugin_name, const unsigned int flags)
+{
+    *dest = GetProcAddress(module, symbol);
+    if ((flags & PLUGIN_SYMBOL_REQUIRED) && !*dest)
+    {
+        msg(M_FATAL, "PLUGIN: could not find required symbol '%s' in plugin DLL %s", symbol, plugin_name);
+    }
+}
+
+#endif /* ifndef _WIN32 */
+
+static void
+plugin_init_item(struct plugin *p, const struct plugin_option *o)
+{
+    struct gc_arena gc = gc_new();
+    bool rel = false;
+
+    p->so_pathname = o->so_pathname;
+    p->plugin_type_mask = plugin_supported_types();
+
+#ifndef _WIN32
+
+    p->handle = NULL;
+
+    /* If the plug-in filename is not an absolute path,
+     * or beginning with '.', it should use the PLUGIN_LIBDIR
+     * as the base directory for loading the plug-in.
+     *
+     * This means the following scenarios are loaded from these places:
+     *    --plugin fancyplug.so              -> $PLUGIN_LIBDIR/fancyplug.so
+     *    --plugin my/fancyplug.so           -> $PLUGIN_LIBDIR/my/fancyplug.so
+     *    --plugin ./fancyplug.so            -> $CWD/fancyplug.so
+     *    --plugin /usr/lib/my/fancyplug.so  -> /usr/lib/my/fancyplug.so
+     *
+     * Please note that $CWD means the directory OpenVPN is either started from
+     * or the directory OpenVPN have changed into using --cd before --plugin
+     * was parsed.
+     *
+     */
+    if (!absolute_pathname(p->so_pathname)
+        && p->so_pathname[0] != '.')
+    {
+        char full[PATH_MAX];
+
+        openvpn_snprintf(full, sizeof(full), "%s/%s", PLUGIN_LIBDIR, p->so_pathname);
+        p->handle = dlopen(full, RTLD_NOW);
+    }
+    else
+    {
+        rel = !absolute_pathname(p->so_pathname);
+        p->handle = dlopen(p->so_pathname, RTLD_NOW);
+    }
+    if (!p->handle)
+    {
+        msg(M_ERR, "PLUGIN_INIT: could not load plugin shared object %s: %s", p->so_pathname, dlerror());
+    }
+
+#define PLUGIN_SYM(var, name, flags) libdl_resolve_symbol(p->handle, (void *)&p->var, name, p->so_pathname, flags)
+
+#else  /* ifndef _WIN32 */
+
+    rel = !absolute_pathname(p->so_pathname);
+    p->module = LoadLibraryW(wide_string(p->so_pathname, &gc));
+    if (!p->module)
+    {
+        msg(M_ERR, "PLUGIN_INIT: could not load plugin DLL: %s", p->so_pathname);
+    }
+
+#define PLUGIN_SYM(var, name, flags) dll_resolve_symbol(p->module, (void *)&p->var, name, p->so_pathname, flags)
+
+#endif /* ifndef _WIN32 */
+
+    PLUGIN_SYM(open1, "openvpn_plugin_open_v1", 0);
+    PLUGIN_SYM(open2, "openvpn_plugin_open_v2", 0);
+    PLUGIN_SYM(open3, "openvpn_plugin_open_v3", 0);
+    PLUGIN_SYM(func1, "openvpn_plugin_func_v1", 0);
+    PLUGIN_SYM(func2, "openvpn_plugin_func_v2", 0);
+    PLUGIN_SYM(func3, "openvpn_plugin_func_v3", 0);
+    PLUGIN_SYM(close, "openvpn_plugin_close_v1", PLUGIN_SYMBOL_REQUIRED);
+    PLUGIN_SYM(abort, "openvpn_plugin_abort_v1", 0);
+    PLUGIN_SYM(client_constructor, "openvpn_plugin_client_constructor_v1", 0);
+    PLUGIN_SYM(client_destructor, "openvpn_plugin_client_destructor_v1", 0);
+    PLUGIN_SYM(min_version_required, "openvpn_plugin_min_version_required_v1", 0);
+    PLUGIN_SYM(initialization_point, "openvpn_plugin_select_initialization_point_v1", 0);
+
+    if (!p->open1 && !p->open2 && !p->open3)
+    {
+        msg(M_FATAL, "PLUGIN: symbol openvpn_plugin_open_vX is undefined in plugin: %s", p->so_pathname);
+    }
+
+    if (!p->func1 && !p->func2 && !p->func3)
+    {
+        msg(M_FATAL, "PLUGIN: symbol openvpn_plugin_func_vX is undefined in plugin: %s", p->so_pathname);
+    }
+
+    /*
+     * Verify that we are sufficiently up-to-date to handle the plugin
+     */
+    if (p->min_version_required)
+    {
+        const int plugin_needs_version = (*p->min_version_required)();
+        if (plugin_needs_version > OPENVPN_PLUGIN_VERSION)
+        {
+            msg(M_FATAL, "PLUGIN_INIT: plugin needs interface version %d, but this version of OpenVPN only supports version %d: %s",
+                plugin_needs_version,
+                OPENVPN_PLUGIN_VERSION,
+                p->so_pathname);
+        }
+    }
+
+    if (p->initialization_point)
+    {
+        p->requested_initialization_point = (*p->initialization_point)();
+    }
+    else
+    {
+        p->requested_initialization_point = OPENVPN_PLUGIN_INIT_PRE_DAEMON;
+    }
+
+    if (rel)
+    {
+        msg(M_WARN, "WARNING: plugin '%s' specified by a relative pathname -- using an absolute pathname would be more secure", p->so_pathname);
+    }
+
+    p->initialized = true;
+
+    gc_free(&gc);
+}
+
+static void
+plugin_vlog(openvpn_plugin_log_flags_t flags, const char *name, const char *format, va_list arglist)
+{
+    unsigned int msg_flags = 0;
+
+    if (!format)
+    {
+        return;
+    }
+
+    if (!name || name[0] == '\0')
+    {
+        msg(D_PLUGIN_DEBUG, "PLUGIN: suppressed log message from plugin with unknown name");
+        return;
+    }
+
+    if (flags & PLOG_ERR)
+    {
+        msg_flags = M_INFO | M_NONFATAL;
+    }
+    else if (flags & PLOG_WARN)
+    {
+        msg_flags = M_INFO | M_WARN;
+    }
+    else if (flags & PLOG_NOTE)
+    {
+        msg_flags = M_INFO;
+    }
+    else if (flags & PLOG_DEBUG)
+    {
+        msg_flags = D_PLUGIN_DEBUG;
+    }
+
+    if (flags & PLOG_ERRNO)
+    {
+        msg_flags |= M_ERRNO;
+    }
+    if (flags & PLOG_NOMUTE)
+    {
+        msg_flags |= M_NOMUTE;
+    }
+
+    if (msg_test(msg_flags))
+    {
+        struct gc_arena gc;
+        char *msg_fmt;
+
+        /* Never add instance prefix; not thread safe */
+        msg_flags |= M_NOIPREFIX;
+
+        gc_init(&gc);
+        msg_fmt = gc_malloc(ERR_BUF_SIZE, false, &gc);
+        openvpn_snprintf(msg_fmt, ERR_BUF_SIZE, "PLUGIN %s: %s", name, format);
+        x_msg_va(msg_flags, msg_fmt, arglist);
+
+        gc_free(&gc);
+    }
+}
+
+static void
+plugin_log(openvpn_plugin_log_flags_t flags, const char *name, const char *format, ...)
+{
+    va_list arglist;
+    va_start(arglist, format);
+    plugin_vlog(flags, name, format, arglist);
+    va_end(arglist);
+}
+
+static struct openvpn_plugin_callbacks callbacks = {
+    plugin_log,
+    plugin_vlog,
+    secure_memzero,         /* plugin_secure_memzero */
+    openvpn_base64_encode,  /* plugin_base64_encode */
+    openvpn_base64_decode,  /* plugin_base64_decode */
+};
+
+
+/* Provide a wrapper macro for a version patch level string to plug-ins.
+ * This is located here purely to not make the code too messy with #ifndef
+ * inside a struct declaration
+ */
+#ifndef CONFIGURE_GIT_REVISION
+#define _OPENVPN_PATCH_LEVEL OPENVPN_VERSION_PATCH
+#else
+#define _OPENVPN_PATCH_LEVEL "git:" CONFIGURE_GIT_REVISION CONFIGURE_GIT_FLAGS
+#endif
+
+static void
+plugin_open_item(struct plugin *p,
+                 const struct plugin_option *o,
+                 struct openvpn_plugin_string_list **retlist,
+                 const char **envp,
+                 const int init_point)
+{
+    ASSERT(p->initialized);
+
+    /* clear return list */
+    if (retlist)
+    {
+        *retlist = NULL;
+    }
+
+    if (!p->plugin_handle && init_point == p->requested_initialization_point)
+    {
+        struct gc_arena gc = gc_new();
+
+        dmsg(D_PLUGIN_DEBUG, "PLUGIN_INIT: PRE");
+        plugin_show_args_env(D_PLUGIN_DEBUG, o->argv, envp);
+
+        /*
+         * Call the plugin initialization
+         */
+        if (p->open3)
+        {
+            struct openvpn_plugin_args_open_in args = { p->plugin_type_mask,
+                                                        (const char **const) o->argv,
+                                                        (const char **const) envp,
+                                                        &callbacks,
+                                                        SSLAPI,
+                                                        PACKAGE_VERSION,
+                                                        OPENVPN_VERSION_MAJOR,
+                                                        OPENVPN_VERSION_MINOR,
+                                                        _OPENVPN_PATCH_LEVEL};
+            struct openvpn_plugin_args_open_return retargs;
+
+            CLEAR(retargs);
+            retargs.return_list = retlist;
+            if ((*p->open3)(OPENVPN_PLUGINv3_STRUCTVER, &args, &retargs) == OPENVPN_PLUGIN_FUNC_SUCCESS)
+            {
+                p->plugin_type_mask = retargs.type_mask;
+                p->plugin_handle = retargs.handle;
+            }
+            else
+            {
+                p->plugin_handle = NULL;
+            }
+        }
+        else if (p->open2)
+        {
+            p->plugin_handle = (*p->open2)(&p->plugin_type_mask, o->argv, envp, retlist);
+        }
+        else if (p->open1)
+        {
+            p->plugin_handle = (*p->open1)(&p->plugin_type_mask, o->argv, envp);
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        msg(D_PLUGIN, "PLUGIN_INIT: POST %s '%s' intercepted=%s %s",
+            p->so_pathname,
+            print_argv(o->argv, &gc, PA_BRACKET),
+            plugin_mask_string(p->plugin_type_mask, &gc),
+            (retlist && *retlist) ? "[RETLIST]" : "");
+
+        if ((p->plugin_type_mask | plugin_supported_types()) != plugin_supported_types())
+        {
+            msg(M_FATAL, "PLUGIN_INIT: plugin %s expressed interest in unsupported plugin types: [want=0x%08x, have=0x%08x]",
+                p->so_pathname,
+                p->plugin_type_mask,
+                plugin_supported_types());
+        }
+
+        if (p->plugin_handle == NULL)
+        {
+            msg(M_FATAL, "PLUGIN_INIT: plugin initialization function failed: %s",
+                p->so_pathname);
+        }
+
+        gc_free(&gc);
+    }
+}
+
+static int
+plugin_call_item(const struct plugin *p,
+                 void *per_client_context,
+                 const int type,
+                 const struct argv *av,
+                 struct openvpn_plugin_string_list **retlist,
+                 const char **envp
+#ifdef ENABLE_CRYPTO
+                 , int certdepth,
+                 openvpn_x509_cert_t *current_cert
+#endif
+                 )
+{
+    int status = OPENVPN_PLUGIN_FUNC_SUCCESS;
+
+    /* clear return list */
+    if (retlist)
+    {
+        *retlist = NULL;
+    }
+
+    if (p->plugin_handle && (p->plugin_type_mask & OPENVPN_PLUGIN_MASK(type)))
+    {
+        struct gc_arena gc = gc_new();
+        struct argv a = argv_insert_head(av, p->so_pathname);
+
+        dmsg(D_PLUGIN_DEBUG, "PLUGIN_CALL: PRE type=%s", plugin_type_name(type));
+        plugin_show_args_env(D_PLUGIN_DEBUG, (const char **)a.argv, envp);
+
+        /*
+         * Call the plugin work function
+         */
+        if (p->func3)
+        {
+            struct openvpn_plugin_args_func_in args = { type,
+                                                        (const char **const) a.argv,
+                                                        (const char **const) envp,
+                                                        p->plugin_handle,
+                                                        per_client_context,
+#ifdef ENABLE_CRYPTO
+                                                        (current_cert ? certdepth : -1),
+                                                        current_cert
+#else
+                                                        -1,
+                                                        NULL
+#endif
+            };
+
+            struct openvpn_plugin_args_func_return retargs;
+
+            CLEAR(retargs);
+            retargs.return_list = retlist;
+            status = (*p->func3)(OPENVPN_PLUGINv3_STRUCTVER, &args, &retargs);
+        }
+        else if (p->func2)
+        {
+            status = (*p->func2)(p->plugin_handle, type, (const char **)a.argv, envp, per_client_context, retlist);
+        }
+        else if (p->func1)
+        {
+            status = (*p->func1)(p->plugin_handle, type, (const char **)a.argv, envp);
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        msg(D_PLUGIN, "PLUGIN_CALL: POST %s/%s status=%d",
+            p->so_pathname,
+            plugin_type_name(type),
+            status);
+
+        if (status == OPENVPN_PLUGIN_FUNC_ERROR)
+        {
+            msg(M_WARN, "PLUGIN_CALL: plugin function %s failed with status %d: %s",
+                plugin_type_name(type),
+                status,
+                p->so_pathname);
+        }
+
+        argv_reset(&a);
+        gc_free(&gc);
+    }
+    return status;
+}
+
+static void
+plugin_close_item(struct plugin *p)
+{
+    if (p->initialized)
+    {
+        msg(D_PLUGIN, "PLUGIN_CLOSE: %s", p->so_pathname);
+
+        /*
+         * Call the plugin close function
+         */
+        if (p->plugin_handle)
+        {
+            (*p->close)(p->plugin_handle);
+        }
+
+#ifndef _WIN32
+        if (dlclose(p->handle))
+        {
+            msg(M_WARN, "PLUGIN_CLOSE: dlclose() failed on plugin: %s", p->so_pathname);
+        }
+#elif defined(_WIN32)
+        if (!FreeLibrary(p->module))
+        {
+            msg(M_WARN, "PLUGIN_CLOSE: FreeLibrary() failed on plugin: %s", p->so_pathname);
+        }
+#endif
+
+        p->initialized = false;
+    }
+}
+
+static void
+plugin_abort_item(const struct plugin *p)
+{
+    /*
+     * Call the plugin abort function
+     */
+    if (p->abort)
+    {
+        (*p->abort)(p->plugin_handle);
+    }
+}
+
+static void
+plugin_per_client_init(const struct plugin_common *pc,
+                       struct plugin_per_client *cli,
+                       const int init_point)
+{
+    const int n = pc->n;
+    int i;
+
+    for (i = 0; i < n; ++i)
+    {
+        const struct plugin *p = &pc->plugins[i];
+        if (p->plugin_handle
+            && (init_point < 0 || init_point == p->requested_initialization_point)
+            && p->client_constructor)
+        {
+            cli->per_client_context[i] = (*p->client_constructor)(p->plugin_handle);
+        }
+    }
+}
+
+static void
+plugin_per_client_destroy(const struct plugin_common *pc, struct plugin_per_client *cli)
+{
+    const int n = pc->n;
+    int i;
+
+    for (i = 0; i < n; ++i)
+    {
+        const struct plugin *p = &pc->plugins[i];
+        void *cc = cli->per_client_context[i];
+
+        if (p->client_destructor && cc)
+        {
+            (*p->client_destructor)(p->plugin_handle, cc);
+        }
+    }
+    CLEAR(*cli);
+}
+
+struct plugin_list *
+plugin_list_inherit(const struct plugin_list *src)
+{
+    struct plugin_list *pl;
+    ALLOC_OBJ_CLEAR(pl, struct plugin_list);
+    pl->common = src->common;
+    ASSERT(pl->common);
+    plugin_per_client_init(pl->common, &pl->per_client, -1);
+    return pl;
+}
+
+static struct plugin_common *
+plugin_common_init(const struct plugin_option_list *list)
+{
+    int i;
+    struct plugin_common *pc;
+
+    ALLOC_OBJ_CLEAR(pc, struct plugin_common);
+
+    for (i = 0; i < list->n; ++i)
+    {
+        plugin_init_item(&pc->plugins[i],
+                         &list->plugins[i]);
+        pc->n = i + 1;
+    }
+
+    static_plugin_common = pc;
+    return pc;
+}
+
+static void
+plugin_common_open(struct plugin_common *pc,
+                   const struct plugin_option_list *list,
+                   struct plugin_return *pr,
+                   const struct env_set *es,
+                   const int init_point)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    const char **envp;
+
+    envp = make_env_array(es, false, &gc);
+
+    if (pr)
+    {
+        plugin_return_init(pr);
+    }
+
+    for (i = 0; i < pc->n; ++i)
+    {
+        plugin_open_item(&pc->plugins[i],
+                         &list->plugins[i],
+                         pr ? &pr->list[i] : NULL,
+                         envp,
+                         init_point);
+    }
+
+    if (pr)
+    {
+        pr->n = i;
+    }
+
+    gc_free(&gc);
+}
+
+static void
+plugin_common_close(struct plugin_common *pc)
+{
+    static_plugin_common = NULL;
+    if (pc)
+    {
+        int i;
+
+        for (i = 0; i < pc->n; ++i)
+        {
+            plugin_close_item(&pc->plugins[i]);
+        }
+        free(pc);
+    }
+}
+
+struct plugin_list *
+plugin_list_init(const struct plugin_option_list *list)
+{
+    struct plugin_list *pl;
+    ALLOC_OBJ_CLEAR(pl, struct plugin_list);
+    pl->common = plugin_common_init(list);
+    pl->common_owned = true;
+    return pl;
+}
+
+void
+plugin_list_open(struct plugin_list *pl,
+                 const struct plugin_option_list *list,
+                 struct plugin_return *pr,
+                 const struct env_set *es,
+                 const int init_point)
+{
+    plugin_common_open(pl->common, list, pr, es, init_point);
+    plugin_per_client_init(pl->common, &pl->per_client, init_point);
+}
+
+int
+plugin_call_ssl(const struct plugin_list *pl,
+                const int type,
+                const struct argv *av,
+                struct plugin_return *pr,
+                struct env_set *es
+#ifdef ENABLE_CRYPTO
+                , int certdepth,
+                openvpn_x509_cert_t *current_cert
+#endif
+                )
+{
+    if (pr)
+    {
+        plugin_return_init(pr);
+    }
+
+    if (plugin_defined(pl, type))
+    {
+        struct gc_arena gc = gc_new();
+        int i;
+        const char **envp;
+        const int n = plugin_n(pl);
+        bool success = false;
+        bool error = false;
+        bool deferred = false;
+
+        setenv_del(es, "script_type");
+        envp = make_env_array(es, false, &gc);
+
+        for (i = 0; i < n; ++i)
+        {
+            const int status = plugin_call_item(&pl->common->plugins[i],
+                                                pl->per_client.per_client_context[i],
+                                                type,
+                                                av,
+                                                pr ? &pr->list[i] : NULL,
+                                                envp
+#ifdef ENABLE_CRYPTO
+                                                ,certdepth,
+                                                current_cert
+#endif
+                                                );
+            switch (status)
+            {
+                case OPENVPN_PLUGIN_FUNC_SUCCESS:
+                    success = true;
+                    break;
+
+                case OPENVPN_PLUGIN_FUNC_DEFERRED:
+                    deferred = true;
+                    break;
+
+                default:
+                    error = true;
+                    break;
+            }
+        }
+
+        if (pr)
+        {
+            pr->n = i;
+        }
+
+        gc_free(&gc);
+
+        if (type == OPENVPN_PLUGIN_ENABLE_PF && success)
+        {
+            return OPENVPN_PLUGIN_FUNC_SUCCESS;
+        }
+        else if (error)
+        {
+            return OPENVPN_PLUGIN_FUNC_ERROR;
+        }
+        else if (deferred)
+        {
+            return OPENVPN_PLUGIN_FUNC_DEFERRED;
+        }
+    }
+
+    return OPENVPN_PLUGIN_FUNC_SUCCESS;
+}
+
+void
+plugin_list_close(struct plugin_list *pl)
+{
+    if (pl)
+    {
+        if (pl->common)
+        {
+            plugin_per_client_destroy(pl->common, &pl->per_client);
+
+            if (pl->common_owned)
+            {
+                plugin_common_close(pl->common);
+            }
+        }
+
+        free(pl);
+    }
+}
+
+void
+plugin_abort(void)
+{
+    struct plugin_common *pc = static_plugin_common;
+    static_plugin_common = NULL;
+    if (pc)
+    {
+        int i;
+
+        for (i = 0; i < pc->n; ++i)
+        {
+            plugin_abort_item(&pc->plugins[i]);
+        }
+    }
+}
+
+bool
+plugin_defined(const struct plugin_list *pl, const int type)
+{
+    bool ret = false;
+
+    if (pl)
+    {
+        const struct plugin_common *pc = pl->common;
+
+        if (pc)
+        {
+            int i;
+            const unsigned int mask = OPENVPN_PLUGIN_MASK(type);
+            for (i = 0; i < pc->n; ++i)
+            {
+                if (pc->plugins[i].plugin_type_mask & mask)
+                {
+                    ret = true;
+                    break;
+                }
+            }
+        }
+    }
+    return ret;
+}
+
+/*
+ * Plugin return functions
+ */
+
+static void
+openvpn_plugin_string_list_item_free(struct openvpn_plugin_string_list *l)
+{
+    if (l)
+    {
+        free(l->name);
+        string_clear(l->value);
+        free(l->value);
+        free(l);
+    }
+}
+
+static void
+openvpn_plugin_string_list_free(struct openvpn_plugin_string_list *l)
+{
+    struct openvpn_plugin_string_list *next;
+    while (l)
+    {
+        next = l->next;
+        openvpn_plugin_string_list_item_free(l);
+        l = next;
+    }
+}
+
+static struct openvpn_plugin_string_list *
+openvpn_plugin_string_list_find(struct openvpn_plugin_string_list *l, const char *name)
+{
+    while (l)
+    {
+        if (!strcmp(l->name, name))
+        {
+            return l;
+        }
+        l = l->next;
+    }
+    return NULL;
+}
+
+void
+plugin_return_get_column(const struct plugin_return *src,
+                         struct plugin_return *dest,
+                         const char *colname)
+{
+    int i;
+
+    dest->n = 0;
+    for (i = 0; i < src->n; ++i)
+    {
+        dest->list[i] = openvpn_plugin_string_list_find(src->list[i], colname);
+    }
+    dest->n = i;
+}
+
+void
+plugin_return_free(struct plugin_return *pr)
+{
+    int i;
+    for (i = 0; i < pr->n; ++i)
+    {
+        openvpn_plugin_string_list_free(pr->list[i]);
+    }
+    pr->n = 0;
+}
+
+#ifdef ENABLE_DEBUG
+void
+plugin_return_print(const int msglevel, const char *prefix, const struct plugin_return *pr)
+{
+    int i;
+    msg(msglevel, "PLUGIN_RETURN_PRINT %s", prefix);
+    for (i = 0; i < pr->n; ++i)
+    {
+        struct openvpn_plugin_string_list *l = pr->list[i];
+        int count = 0;
+
+        msg(msglevel, "PLUGIN #%d (%s)", i, prefix);
+        while (l)
+        {
+            msg(msglevel, "[%d] '%s' -> '%s'\n",
+                ++count,
+                l->name,
+                l->value);
+            l = l->next;
+        }
+    }
+}
+#endif /* ifdef ENABLE_DEBUG */
+
+#else  /* ifdef ENABLE_PLUGIN */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_PLUGIN */
diff --git a/src/openvpn/plugin.h b/src/openvpn/plugin.h
new file mode 100644
index 0000000..ec2d1fe
--- /dev/null
+++ b/src/openvpn/plugin.h
@@ -0,0 +1,218 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * plug-in support, using dynamically loaded libraries
+ */
+
+#ifndef OPENVPN_PLUGIN_H
+#define OPENVPN_PLUGIN_H
+
+#ifdef ENABLE_CRYPTO_OPENSSL
+#include "ssl_verify_openssl.h"
+#endif
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include "ssl_verify_mbedtls.h"
+#endif
+#include "openvpn-plugin.h"
+
+#ifdef ENABLE_PLUGIN
+
+#include "misc.h"
+
+#define MAX_PLUGINS 16
+
+struct plugin_option {
+    const char *so_pathname;
+    const char **argv;
+};
+
+struct plugin_option_list {
+    int n;
+    struct plugin_option plugins[MAX_PLUGINS];
+};
+
+struct plugin {
+    bool initialized;
+    const char *so_pathname;
+    unsigned int plugin_type_mask;
+    int requested_initialization_point;
+
+#ifndef _WIN32
+    void *handle;
+#else
+    HMODULE module;
+#endif
+
+    openvpn_plugin_open_v1 open1;
+    openvpn_plugin_open_v2 open2;
+    openvpn_plugin_open_v3 open3;
+    openvpn_plugin_func_v1 func1;
+    openvpn_plugin_func_v2 func2;
+    openvpn_plugin_func_v3 func3;
+    openvpn_plugin_close_v1 close;
+    openvpn_plugin_abort_v1 abort;
+    openvpn_plugin_client_constructor_v1 client_constructor;
+    openvpn_plugin_client_destructor_v1 client_destructor;
+    openvpn_plugin_min_version_required_v1 min_version_required;
+    openvpn_plugin_select_initialization_point_v1 initialization_point;
+
+    openvpn_plugin_handle_t plugin_handle;
+};
+
+struct plugin_per_client
+{
+    void *per_client_context[MAX_PLUGINS];
+};
+
+struct plugin_common
+{
+    int n;
+    struct plugin plugins[MAX_PLUGINS];
+};
+
+struct plugin_list
+{
+    struct plugin_per_client per_client;
+    struct plugin_common *common;
+    bool common_owned;
+};
+
+struct plugin_return
+{
+    int n;
+    struct openvpn_plugin_string_list *list[MAX_PLUGINS];
+};
+
+struct plugin_option_list *plugin_option_list_new(struct gc_arena *gc);
+
+bool plugin_option_list_add(struct plugin_option_list *list, char **p, struct gc_arena *gc);
+
+#ifndef ENABLE_SMALL
+void plugin_option_list_print(const struct plugin_option_list *list, int msglevel);
+
+#endif
+
+struct plugin_list *plugin_list_init(const struct plugin_option_list *list);
+
+void plugin_list_open(struct plugin_list *pl,
+                      const struct plugin_option_list *list,
+                      struct plugin_return *pr,
+                      const struct env_set *es,
+                      const int init_point);
+
+struct plugin_list *plugin_list_inherit(const struct plugin_list *src);
+
+int plugin_call_ssl(const struct plugin_list *pl,
+                    const int type,
+                    const struct argv *av,
+                    struct plugin_return *pr,
+                    struct env_set *es
+#ifdef ENABLE_CRYPTO
+                    , int current_cert_depth,
+                    openvpn_x509_cert_t *current_cert
+#endif
+                    );
+
+void plugin_list_close(struct plugin_list *pl);
+
+bool plugin_defined(const struct plugin_list *pl, const int type);
+
+void plugin_return_get_column(const struct plugin_return *src,
+                              struct plugin_return *dest,
+                              const char *colname);
+
+void plugin_return_free(struct plugin_return *pr);
+
+#ifdef ENABLE_DEBUG
+void plugin_return_print(const int msglevel, const char *prefix, const struct plugin_return *pr);
+
+#endif
+
+static inline int
+plugin_n(const struct plugin_list *pl)
+{
+    if (pl && pl->common)
+    {
+        return pl->common->n;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static inline bool
+plugin_return_defined(const struct plugin_return *pr)
+{
+    return pr->n >= 0;
+}
+
+static inline void
+plugin_return_init(struct plugin_return *pr)
+{
+    pr->n = 0;
+}
+
+#else  /* ifdef ENABLE_PLUGIN */
+struct plugin_list { int dummy; };
+struct plugin_return { int dummy; };
+
+static inline bool
+plugin_defined(const struct plugin_list *pl, const int type)
+{
+    return false;
+}
+
+static inline int
+plugin_call_ssl(const struct plugin_list *pl,
+                const int type,
+                const struct argv *av,
+                struct plugin_return *pr,
+                struct env_set *es
+#ifdef ENABLE_CRYPTO
+                , int current_cert_depth,
+                openvpn_x509_cert_t *current_cert
+#endif
+                )
+{
+    return 0;
+}
+
+#endif /* ENABLE_PLUGIN */
+
+static inline int
+plugin_call(const struct plugin_list *pl,
+            const int type,
+            const struct argv *av,
+            struct plugin_return *pr,
+            struct env_set *es)
+{
+    return plugin_call_ssl(pl, type, av, pr, es
+#ifdef ENABLE_CRYPTO
+                           , -1, NULL
+#endif
+                           );
+}
+
+#endif /* OPENVPN_PLUGIN_H */
diff --git a/src/openvpn/pool.c b/src/openvpn/pool.c
new file mode 100644
index 0000000..da28bc0
--- /dev/null
+++ b/src/openvpn/pool.c
@@ -0,0 +1,628 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "pool.h"
+#include "buffer.h"
+#include "error.h"
+#include "socket.h"
+#include "otime.h"
+
+#include "memdbg.h"
+
+#if P2MP
+
+static void
+ifconfig_pool_entry_free(struct ifconfig_pool_entry *ipe, bool hard)
+{
+    ipe->in_use = false;
+    if (hard && ipe->common_name)
+    {
+        free(ipe->common_name);
+        ipe->common_name = NULL;
+    }
+    if (hard)
+    {
+        ipe->last_release = 0;
+    }
+    else
+    {
+        ipe->last_release = now;
+    }
+}
+
+static int
+ifconfig_pool_find(struct ifconfig_pool *pool, const char *common_name)
+{
+    int i;
+    time_t earliest_release = 0;
+    int previous_usage = -1;
+    int new_usage = -1;
+
+    for (i = 0; i < pool->size; ++i)
+    {
+        struct ifconfig_pool_entry *ipe = &pool->list[i];
+        if (!ipe->in_use)
+        {
+            /*
+             * If duplicate_cn mode, take first available IP address
+             */
+            if (pool->duplicate_cn)
+            {
+                new_usage = i;
+                break;
+            }
+
+            /*
+             * Keep track of the unused IP address entry which
+             * was released earliest.
+             */
+            if ((new_usage == -1 || ipe->last_release < earliest_release) && !ipe->fixed)
+            {
+                earliest_release = ipe->last_release;
+                new_usage = i;
+            }
+
+            /*
+             * Keep track of a possible allocation to us
+             * from an earlier session.
+             */
+            if (previous_usage < 0
+                && common_name
+                && ipe->common_name
+                && !strcmp(common_name, ipe->common_name))
+            {
+                previous_usage = i;
+            }
+
+        }
+    }
+
+    if (previous_usage >= 0)
+    {
+        return previous_usage;
+    }
+
+    if (new_usage >= 0)
+    {
+        return new_usage;
+    }
+
+    return -1;
+}
+
+/*
+ * Verify start/end range
+ */
+bool
+ifconfig_pool_verify_range(const int msglevel, const in_addr_t start, const in_addr_t end)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = true;
+
+    if (start > end)
+    {
+        msg(msglevel, "--ifconfig-pool start IP [%s] is greater than end IP [%s]",
+            print_in_addr_t(start, 0, &gc),
+            print_in_addr_t(end, 0, &gc));
+        ret = false;
+    }
+    if (end - start >= IFCONFIG_POOL_MAX)
+    {
+        msg(msglevel, "--ifconfig-pool address range is too large [%s -> %s].  Current maximum is %d addresses, as defined by IFCONFIG_POOL_MAX variable.",
+            print_in_addr_t(start, 0, &gc),
+            print_in_addr_t(end, 0, &gc),
+            IFCONFIG_POOL_MAX);
+        ret = false;
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+struct ifconfig_pool *
+ifconfig_pool_init(int type, in_addr_t start, in_addr_t end,
+                   const bool duplicate_cn,
+                   const bool ipv6_pool, const struct in6_addr ipv6_base,
+                   const int ipv6_netbits )
+{
+    struct gc_arena gc = gc_new();
+    struct ifconfig_pool *pool = NULL;
+
+    ASSERT(start <= end && end - start < IFCONFIG_POOL_MAX);
+    ALLOC_OBJ_CLEAR(pool, struct ifconfig_pool);
+
+    pool->type = type;
+    pool->duplicate_cn = duplicate_cn;
+
+    switch (type)
+    {
+        case IFCONFIG_POOL_30NET:
+            pool->base = start & ~3;
+            pool->size = (((end | 3) + 1) - pool->base) >> 2;
+            break;
+
+        case IFCONFIG_POOL_INDIV:
+            pool->base = start;
+            pool->size = end - start + 1;
+            break;
+
+        default:
+            ASSERT(0);
+    }
+
+    /* IPv6 pools are always "INDIV" type */
+    pool->ipv6 = ipv6_pool;
+
+    if (pool->ipv6)
+    {
+        pool->base_ipv6 = ipv6_base;
+        pool->size_ipv6 = ipv6_netbits>96 ? ( 1<<(128-ipv6_netbits) )
+                          : IFCONFIG_POOL_MAX;
+
+        msg( D_IFCONFIG_POOL, "IFCONFIG POOL IPv6: (IPv4) size=%d, size_ipv6=%d, netbits=%d, base_ipv6=%s",
+             pool->size, pool->size_ipv6, ipv6_netbits,
+             print_in6_addr( pool->base_ipv6, 0, &gc ));
+
+        /* the current code is very simple and assumes that the IPv6
+         * pool is at least as big as the IPv4 pool, and we don't need
+         * to do separate math etc. for IPv6
+         */
+        ASSERT( pool->size < pool->size_ipv6 );
+    }
+
+    ALLOC_ARRAY_CLEAR(pool->list, struct ifconfig_pool_entry, pool->size);
+
+    msg(D_IFCONFIG_POOL, "IFCONFIG POOL: base=%s size=%d, ipv6=%d",
+        print_in_addr_t(pool->base, 0, &gc),
+        pool->size, pool->ipv6 );
+
+    gc_free(&gc);
+    return pool;
+}
+
+void
+ifconfig_pool_free(struct ifconfig_pool *pool)
+{
+    if (pool)
+    {
+        int i;
+        for (i = 0; i < pool->size; ++i)
+        {
+            ifconfig_pool_entry_free(&pool->list[i], true);
+        }
+        free(pool->list);
+        free(pool);
+    }
+}
+
+ifconfig_pool_handle
+ifconfig_pool_acquire(struct ifconfig_pool *pool, in_addr_t *local, in_addr_t *remote, struct in6_addr *remote_ipv6, const char *common_name)
+{
+    int i;
+
+    i = ifconfig_pool_find(pool, common_name);
+    if (i >= 0)
+    {
+        struct ifconfig_pool_entry *ipe = &pool->list[i];
+        ASSERT(!ipe->in_use);
+        ifconfig_pool_entry_free(ipe, true);
+        ipe->in_use = true;
+        if (common_name)
+        {
+            ipe->common_name = string_alloc(common_name, NULL);
+        }
+
+        switch (pool->type)
+        {
+            case IFCONFIG_POOL_30NET:
+            {
+                in_addr_t b = pool->base + (i << 2);
+                *local = b + 1;
+                *remote = b + 2;
+                break;
+            }
+
+            case IFCONFIG_POOL_INDIV:
+            {
+                in_addr_t b = pool->base + i;
+                *local = 0;
+                *remote = b;
+                break;
+            }
+
+            default:
+                ASSERT(0);
+        }
+
+        /* IPv6 pools are always INDIV (--linear) */
+        if (pool->ipv6 && remote_ipv6)
+        {
+            *remote_ipv6 = add_in6_addr( pool->base_ipv6, i );
+        }
+    }
+    return i;
+}
+
+bool
+ifconfig_pool_release(struct ifconfig_pool *pool, ifconfig_pool_handle hand, const bool hard)
+{
+    bool ret = false;
+    if (pool && hand >= 0 && hand < pool->size)
+    {
+        ifconfig_pool_entry_free(&pool->list[hand], hard);
+        ret = true;
+    }
+    return ret;
+}
+
+/*
+ * private access functions
+ */
+
+static ifconfig_pool_handle
+ifconfig_pool_ip_base_to_handle(const struct ifconfig_pool *pool, const in_addr_t addr)
+{
+    ifconfig_pool_handle ret = -1;
+
+    switch (pool->type)
+    {
+        case IFCONFIG_POOL_30NET:
+        {
+            ret = (addr - pool->base) >> 2;
+            break;
+        }
+
+        case IFCONFIG_POOL_INDIV:
+        {
+            ret = (addr - pool->base);
+            break;
+        }
+
+        default:
+            ASSERT(0);
+    }
+
+    if (ret < 0 || ret >= pool->size)
+    {
+        ret = -1;
+    }
+
+    return ret;
+}
+
+static in_addr_t
+ifconfig_pool_handle_to_ip_base(const struct ifconfig_pool *pool, ifconfig_pool_handle hand)
+{
+    in_addr_t ret = 0;
+
+    if (hand >= 0 && hand < pool->size)
+    {
+        switch (pool->type)
+        {
+            case IFCONFIG_POOL_30NET:
+            {
+                ret = pool->base + (hand << 2);
+                break;
+            }
+
+            case IFCONFIG_POOL_INDIV:
+            {
+                ret = pool->base + hand;
+                break;
+            }
+
+            default:
+                ASSERT(0);
+        }
+    }
+
+    return ret;
+}
+
+static struct in6_addr
+ifconfig_pool_handle_to_ipv6_base(const struct ifconfig_pool *pool, ifconfig_pool_handle hand)
+{
+    struct in6_addr ret = in6addr_any;
+
+    /* IPv6 pools are always INDIV (--linear) */
+    if (hand >= 0 && hand < pool->size_ipv6)
+    {
+        ret = add_in6_addr( pool->base_ipv6, hand );
+    }
+    return ret;
+}
+
+static void
+ifconfig_pool_set(struct ifconfig_pool *pool, const char *cn, const in_addr_t addr, const bool fixed)
+{
+    ifconfig_pool_handle h = ifconfig_pool_ip_base_to_handle(pool, addr);
+    if (h >= 0)
+    {
+        struct ifconfig_pool_entry *e = &pool->list[h];
+        ifconfig_pool_entry_free(e, true);
+        e->in_use = false;
+        e->common_name = string_alloc(cn, NULL);
+        e->last_release = now;
+        e->fixed = fixed;
+    }
+}
+
+static void
+ifconfig_pool_list(const struct ifconfig_pool *pool, struct status_output *out)
+{
+    if (pool && out)
+    {
+        struct gc_arena gc = gc_new();
+        int i;
+
+        for (i = 0; i < pool->size; ++i)
+        {
+            const struct ifconfig_pool_entry *e = &pool->list[i];
+            if (e->common_name)
+            {
+                const in_addr_t ip = ifconfig_pool_handle_to_ip_base(pool, i);
+                if (pool->ipv6)
+                {
+                    struct in6_addr ip6 = ifconfig_pool_handle_to_ipv6_base(pool, i);
+                    status_printf(out, "%s,%s,%s",
+                                  e->common_name,
+                                  print_in_addr_t(ip, 0, &gc),
+                                  print_in6_addr(ip6, 0, &gc));
+                }
+                else
+                {
+                    status_printf(out, "%s,%s",
+                                  e->common_name,
+                                  print_in_addr_t(ip, 0, &gc));
+                }
+            }
+        }
+        gc_free(&gc);
+    }
+}
+
+static void
+ifconfig_pool_msg(const struct ifconfig_pool *pool, int msglevel)
+{
+    struct status_output *so = status_open(NULL, 0, msglevel, NULL, 0);
+    ASSERT(so);
+    status_printf(so, "IFCONFIG POOL LIST");
+    ifconfig_pool_list(pool, so);
+    status_close(so);
+}
+
+/*
+ * Deal with reading/writing the ifconfig pool database to a file
+ */
+
+struct ifconfig_pool_persist *
+ifconfig_pool_persist_init(const char *filename, int refresh_freq)
+{
+    struct ifconfig_pool_persist *ret;
+
+    ASSERT(filename);
+
+    ALLOC_OBJ_CLEAR(ret, struct ifconfig_pool_persist);
+    if (refresh_freq > 0)
+    {
+        ret->fixed = false;
+        ret->file = status_open(filename, refresh_freq, -1, NULL, STATUS_OUTPUT_READ|STATUS_OUTPUT_WRITE);
+    }
+    else
+    {
+        ret->fixed = true;
+        ret->file = status_open(filename, 0, -1, NULL, STATUS_OUTPUT_READ);
+    }
+    return ret;
+}
+
+void
+ifconfig_pool_persist_close(struct ifconfig_pool_persist *persist)
+{
+    if (persist)
+    {
+        if (persist->file)
+        {
+            status_close(persist->file);
+        }
+        free(persist);
+    }
+}
+
+bool
+ifconfig_pool_write_trigger(struct ifconfig_pool_persist *persist)
+{
+    if (persist->file)
+    {
+        return status_trigger(persist->file);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+void
+ifconfig_pool_read(struct ifconfig_pool_persist *persist, struct ifconfig_pool *pool)
+{
+    const int buf_size = 128;
+
+    update_time();
+    if (persist && persist->file && pool)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer in = alloc_buf_gc(256, &gc);
+        char *cn_buf;
+        char *ip_buf;
+        int line = 0;
+
+        ALLOC_ARRAY_CLEAR_GC(cn_buf, char, buf_size, &gc);
+        ALLOC_ARRAY_CLEAR_GC(ip_buf, char, buf_size, &gc);
+
+        while (true)
+        {
+            ASSERT(buf_init(&in, 0));
+            if (!status_read(persist->file, &in))
+            {
+                break;
+            }
+            ++line;
+            if (BLEN(&in))
+            {
+                int c = *BSTR(&in);
+                if (c == '#' || c == ';')
+                {
+                    continue;
+                }
+                msg( M_INFO, "ifconfig_pool_read(), in='%s', TODO: IPv6",
+                     BSTR(&in) );
+
+                if (buf_parse(&in, ',', cn_buf, buf_size)
+                    && buf_parse(&in, ',', ip_buf, buf_size))
+                {
+                    bool succeeded;
+                    const in_addr_t addr = getaddr(GETADDR_HOST_ORDER, ip_buf, 0, &succeeded, NULL);
+                    if (succeeded)
+                    {
+                        msg( M_INFO, "succeeded -> ifconfig_pool_set()");
+                        ifconfig_pool_set(pool, cn_buf, addr, persist->fixed);
+                    }
+                }
+            }
+        }
+
+        ifconfig_pool_msg(pool, D_IFCONFIG_POOL);
+
+        gc_free(&gc);
+    }
+}
+
+void
+ifconfig_pool_write(struct ifconfig_pool_persist *persist, const struct ifconfig_pool *pool)
+{
+    if (persist && persist->file && (status_rw_flags(persist->file) & STATUS_OUTPUT_WRITE) && pool)
+    {
+        status_reset(persist->file);
+        ifconfig_pool_list(pool, persist->file);
+        status_flush(persist->file);
+    }
+}
+
+/*
+ * TESTING ONLY
+ */
+
+#ifdef IFCONFIG_POOL_TEST
+
+#define DUP_CN
+
+void
+ifconfig_pool_test(in_addr_t start, in_addr_t end)
+{
+    struct gc_arena gc = gc_new();
+    struct ifconfig_pool *p = ifconfig_pool_init(IFCONFIG_POOL_30NET, start, end);
+    /*struct ifconfig_pool *p = ifconfig_pool_init (IFCONFIG_POOL_INDIV, start, end);*/
+    ifconfig_pool_handle array[256];
+    int i;
+
+    CLEAR(array);
+
+    msg(M_INFO | M_NOPREFIX, "************ 1");
+    for (i = 0; i < (int) SIZE(array); ++i)
+    {
+        char *cn;
+        ifconfig_pool_handle h;
+        in_addr_t local, remote;
+        char buf[256];
+        openvpn_snprintf(buf, sizeof(buf), "common-name-%d", i);
+#ifdef DUP_CN
+        cn = NULL;
+#else
+        cn = buf;
+#endif
+        h = ifconfig_pool_acquire(p, &local, &remote, NULL, cn);
+        if (h < 0)
+        {
+            break;
+        }
+        msg(M_INFO | M_NOPREFIX, "IFCONFIG_POOL TEST pass 1: l=%s r=%s cn=%s",
+            print_in_addr_t(local, 0, &gc),
+            print_in_addr_t(remote, 0, &gc),
+            cn);
+        array[i] = h;
+
+    }
+
+    msg(M_INFO | M_NOPREFIX, "************* 2");
+    for (i = (int) SIZE(array) / 16; i < (int) SIZE(array) / 8; ++i)
+    {
+        msg(M_INFO, "Attempt to release %d cn=%s", array[i], p->list[i].common_name);
+        if (!ifconfig_pool_release(p, array[i]))
+        {
+            break;
+        }
+        msg(M_INFO, "Succeeded");
+    }
+
+    CLEAR(array);
+
+    msg(M_INFO | M_NOPREFIX, "**************** 3");
+    for (i = 0; i < (int) SIZE(array); ++i)
+    {
+        char *cn;
+        ifconfig_pool_handle h;
+        in_addr_t local, remote;
+        char buf[256];
+        snprintf(buf, sizeof(buf), "common-name-%d", i+24);
+#ifdef DUP_CN
+        cn = NULL;
+#else
+        cn = buf;
+#endif
+        h = ifconfig_pool_acquire(p, &local, &remote, NULL, cn);
+        if (h < 0)
+        {
+            break;
+        }
+        msg(M_INFO | M_NOPREFIX, "IFCONFIG_POOL TEST pass 3: l=%s r=%s cn=%s",
+            print_in_addr_t(local, 0, &gc),
+            print_in_addr_t(remote, 0, &gc),
+            cn);
+        array[i] = h;
+
+    }
+
+    ifconfig_pool_free(p);
+    gc_free(&gc);
+}
+
+#endif /* ifdef IFCONFIG_POOL_TEST */
+
+#endif /* if P2MP */
diff --git a/src/openvpn/pool.h b/src/openvpn/pool.h
new file mode 100644
index 0000000..6de28ac
--- /dev/null
+++ b/src/openvpn/pool.h
@@ -0,0 +1,94 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef POOL_H
+#define POOL_H
+
+#if P2MP
+
+/*#define IFCONFIG_POOL_TEST*/
+
+#include "basic.h"
+#include "status.h"
+
+#define IFCONFIG_POOL_MAX         65536
+#define IFCONFIG_POOL_MIN_NETBITS    16
+
+#define IFCONFIG_POOL_30NET   0
+#define IFCONFIG_POOL_INDIV   1
+
+struct ifconfig_pool_entry
+{
+    bool in_use;
+    char *common_name;
+    time_t last_release;
+    bool fixed;
+};
+
+struct ifconfig_pool
+{
+    in_addr_t base;
+    int size;
+    int type;
+    bool duplicate_cn;
+    bool ipv6;
+    struct in6_addr base_ipv6;
+    unsigned int size_ipv6;
+    struct ifconfig_pool_entry *list;
+};
+
+struct ifconfig_pool_persist
+{
+    struct status_output *file;
+    bool fixed;
+};
+
+typedef int ifconfig_pool_handle;
+
+struct ifconfig_pool *ifconfig_pool_init(int type, in_addr_t start, in_addr_t end, const bool duplicate_cn, const bool ipv6_pool, const struct in6_addr ipv6_base, const int ipv6_netbits );
+
+void ifconfig_pool_free(struct ifconfig_pool *pool);
+
+bool ifconfig_pool_verify_range(const int msglevel, const in_addr_t start, const in_addr_t end);
+
+ifconfig_pool_handle ifconfig_pool_acquire(struct ifconfig_pool *pool, in_addr_t *local, in_addr_t *remote, struct in6_addr *remote_ipv6, const char *common_name);
+
+bool ifconfig_pool_release(struct ifconfig_pool *pool, ifconfig_pool_handle hand, const bool hard);
+
+struct ifconfig_pool_persist *ifconfig_pool_persist_init(const char *filename, int refresh_freq);
+
+void ifconfig_pool_persist_close(struct ifconfig_pool_persist *persist);
+
+bool ifconfig_pool_write_trigger(struct ifconfig_pool_persist *persist);
+
+void ifconfig_pool_read(struct ifconfig_pool_persist *persist, struct ifconfig_pool *pool);
+
+void ifconfig_pool_write(struct ifconfig_pool_persist *persist, const struct ifconfig_pool *pool);
+
+#ifdef IFCONFIG_POOL_TEST
+void ifconfig_pool_test(in_addr_t start, in_addr_t end);
+
+#endif
+
+#endif /* if P2MP */
+#endif /* ifndef POOL_H */
diff --git a/src/openvpn/proto.c b/src/openvpn/proto.c
new file mode 100644
index 0000000..87c18e8
--- /dev/null
+++ b/src/openvpn/proto.c
@@ -0,0 +1,156 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "proto.h"
+#include "error.h"
+
+#include "memdbg.h"
+
+/*
+ * If raw tunnel packet is IPv<X>, return true and increment
+ * buffer offset to start of IP header.
+ */
+static
+bool
+is_ipv_X( int tunnel_type, struct buffer *buf, int ip_ver )
+{
+    int offset;
+    const struct openvpn_iphdr *ih;
+
+    verify_align_4(buf);
+    if (tunnel_type == DEV_TYPE_TUN)
+    {
+        if (BLEN(buf) < (int) sizeof(struct openvpn_iphdr))
+        {
+            return false;
+        }
+        offset = 0;
+    }
+    else if (tunnel_type == DEV_TYPE_TAP)
+    {
+        const struct openvpn_ethhdr *eh;
+        if (BLEN(buf) < (int)(sizeof(struct openvpn_ethhdr)
+                              + sizeof(struct openvpn_iphdr)))
+        {
+            return false;
+        }
+        eh = (const struct openvpn_ethhdr *) BPTR(buf);
+        if (ntohs(eh->proto) != (ip_ver == 6 ? OPENVPN_ETH_P_IPV6 : OPENVPN_ETH_P_IPV4))
+        {
+            return false;
+        }
+        offset = sizeof(struct openvpn_ethhdr);
+    }
+    else
+    {
+        return false;
+    }
+
+    ih = (const struct openvpn_iphdr *) (BPTR(buf) + offset);
+
+    /* IP version is stored in the same bits for IPv4 or IPv6 header */
+    if (OPENVPN_IPH_GET_VER(ih->version_len) == ip_ver)
+    {
+        return buf_advance(buf, offset);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+is_ipv4(int tunnel_type, struct buffer *buf)
+{
+    return is_ipv_X( tunnel_type, buf, 4 );
+}
+bool
+is_ipv6(int tunnel_type, struct buffer *buf)
+{
+    return is_ipv_X( tunnel_type, buf, 6 );
+}
+
+#ifdef PACKET_TRUNCATION_CHECK
+
+void
+ipv4_packet_size_verify(const uint8_t *data,
+                        const int size,
+                        const int tunnel_type,
+                        const char *prefix,
+                        counter_type *errors)
+{
+    if (size > 0)
+    {
+        struct buffer buf;
+
+        buf_set_read(&buf, data, size);
+
+        if (is_ipv4(tunnel_type, &buf))
+        {
+            const struct openvpn_iphdr *pip;
+            int hlen;
+            int totlen;
+            const char *msgstr = "PACKET SIZE INFO";
+            unsigned int msglevel = D_PACKET_TRUNC_DEBUG;
+
+            if (BLEN(&buf) < (int) sizeof(struct openvpn_iphdr))
+            {
+                return;
+            }
+
+            verify_align_4(&buf);
+            pip = (struct openvpn_iphdr *) BPTR(&buf);
+
+            hlen = OPENVPN_IPH_GET_LEN(pip->version_len);
+            totlen = ntohs(pip->tot_len);
+
+            if (BLEN(&buf) != totlen)
+            {
+                msgstr = "PACKET TRUNCATION ERROR";
+                msglevel = D_PACKET_TRUNC_ERR;
+                if (errors)
+                {
+                    ++(*errors);
+                }
+            }
+
+            msg(msglevel, "%s %s: size=%d totlen=%d hlen=%d errcount=" counter_format,
+                msgstr,
+                prefix,
+                BLEN(&buf),
+                totlen,
+                hlen,
+                errors ? *errors : (counter_type)0);
+        }
+    }
+}
+
+#endif /* ifdef PACKET_TRUNCATION_CHECK */
diff --git a/src/openvpn/proto.h b/src/openvpn/proto.h
new file mode 100644
index 0000000..985aa99
--- /dev/null
+++ b/src/openvpn/proto.h
@@ -0,0 +1,278 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PROTO_H
+#define PROTO_H
+
+#include "common.h"
+#include "buffer.h"
+
+#pragma pack(1)
+
+/*
+ * Tunnel types
+ */
+#define DEV_TYPE_UNDEF 0
+#define DEV_TYPE_NULL  1
+#define DEV_TYPE_TUN   2    /* point-to-point IP tunnel */
+#define DEV_TYPE_TAP   3    /* ethernet (802.3) tunnel */
+
+/* TUN topologies */
+
+#define TOP_UNDEF   0
+#define TOP_NET30   1
+#define TOP_P2P     2
+#define TOP_SUBNET  3
+
+/*
+ * IP and Ethernet protocol structs.  For portability,
+ * OpenVPN needs its own definitions of these structs, and
+ * names have been adjusted to avoid collisions with
+ * native structs.
+ */
+
+#define OPENVPN_ETH_ALEN 6            /* ethernet address length */
+struct openvpn_ethhdr
+{
+    uint8_t dest[OPENVPN_ETH_ALEN];   /* destination ethernet addr */
+    uint8_t source[OPENVPN_ETH_ALEN]; /* source ethernet addr   */
+
+#define OPENVPN_ETH_P_IPV4   0x0800   /* IPv4 protocol */
+#define OPENVPN_ETH_P_IPV6   0x86DD   /* IPv6 protocol */
+#define OPENVPN_ETH_P_ARP    0x0806   /* ARP protocol */
+    uint16_t proto;                   /* packet type ID field */
+};
+
+struct openvpn_arp {
+#define ARP_MAC_ADDR_TYPE 0x0001
+    uint16_t mac_addr_type;     /* 0x0001 */
+
+    uint16_t proto_addr_type;   /* 0x0800 */
+    uint8_t mac_addr_size;      /* 0x06 */
+    uint8_t proto_addr_size;    /* 0x04 */
+
+#define ARP_REQUEST 0x0001
+#define ARP_REPLY   0x0002
+    uint16_t arp_command;       /* 0x0001 for ARP request, 0x0002 for ARP reply */
+
+    uint8_t mac_src[OPENVPN_ETH_ALEN];
+    in_addr_t ip_src;
+    uint8_t mac_dest[OPENVPN_ETH_ALEN];
+    in_addr_t ip_dest;
+};
+
+struct openvpn_iphdr {
+#define OPENVPN_IPH_GET_VER(v) (((v) >> 4) & 0x0F)
+#define OPENVPN_IPH_GET_LEN(v) (((v) & 0x0F) << 2)
+    uint8_t version_len;
+
+    uint8_t tos;
+    uint16_t tot_len;
+    uint16_t id;
+
+#define OPENVPN_IP_OFFMASK 0x1fff
+    uint16_t frag_off;
+
+    uint8_t ttl;
+
+#define OPENVPN_IPPROTO_IGMP 2  /* IGMP protocol */
+#define OPENVPN_IPPROTO_TCP  6  /* TCP protocol */
+#define OPENVPN_IPPROTO_UDP 17  /* UDP protocol */
+    uint8_t protocol;
+
+    uint16_t check;
+    uint32_t saddr;
+    uint32_t daddr;
+    /*The options start here. */
+};
+
+/*
+ * IPv6 header
+ */
+struct openvpn_ipv6hdr {
+    uint8_t version_prio;
+    uint8_t flow_lbl[3];
+    uint16_t payload_len;
+    uint8_t nexthdr;
+    uint8_t hop_limit;
+
+    struct  in6_addr saddr;
+    struct  in6_addr daddr;
+};
+
+
+/*
+ * UDP header
+ */
+struct openvpn_udphdr {
+    uint16_t source;
+    uint16_t dest;
+    uint16_t len;
+    uint16_t check;
+};
+
+/*
+ * TCP header, per RFC 793.
+ */
+struct openvpn_tcphdr {
+    uint16_t source;       /* source port */
+    uint16_t dest;         /* destination port */
+    uint32_t seq;          /* sequence number */
+    uint32_t ack_seq;      /* acknowledgement number */
+
+#define OPENVPN_TCPH_GET_DOFF(d) (((d) & 0xF0) >> 2)
+    uint8_t doff_res;
+
+#define OPENVPN_TCPH_FIN_MASK (1<<0)
+#define OPENVPN_TCPH_SYN_MASK (1<<1)
+#define OPENVPN_TCPH_RST_MASK (1<<2)
+#define OPENVPN_TCPH_PSH_MASK (1<<3)
+#define OPENVPN_TCPH_ACK_MASK (1<<4)
+#define OPENVPN_TCPH_URG_MASK (1<<5)
+#define OPENVPN_TCPH_ECE_MASK (1<<6)
+#define OPENVPN_TCPH_CWR_MASK (1<<7)
+    uint8_t flags;
+
+    uint16_t window;
+    uint16_t check;
+    uint16_t urg_ptr;
+};
+
+#define OPENVPN_TCPOPT_EOL     0
+#define OPENVPN_TCPOPT_NOP     1
+#define OPENVPN_TCPOPT_MAXSEG  2
+#define OPENVPN_TCPOLEN_MAXSEG 4
+
+struct ip_tcp_udp_hdr {
+    struct openvpn_iphdr ip;
+    union {
+        struct openvpn_tcphdr tcp;
+        struct openvpn_udphdr udp;
+    } u;
+};
+
+#pragma pack()
+
+/*
+ * The following macro is used to update an
+ * internet checksum.  "acc" is a 32-bit
+ * accumulation of all the changes to the
+ * checksum (adding in old 16-bit words and
+ * subtracting out new words), and "cksum"
+ * is the checksum value to be updated.
+ */
+#define ADJUST_CHECKSUM(acc, cksum) { \
+        int _acc = acc; \
+        _acc += (cksum); \
+        if (_acc < 0) { \
+            _acc = -_acc; \
+            _acc = (_acc >> 16) + (_acc & 0xffff); \
+            _acc += _acc >> 16; \
+            (cksum) = (uint16_t) ~_acc; \
+        } else { \
+            _acc = (_acc >> 16) + (_acc & 0xffff); \
+            _acc += _acc >> 16; \
+            (cksum) = (uint16_t) _acc; \
+        } \
+}
+
+#define ADD_CHECKSUM_32(acc, u32) { \
+        acc += (u32) & 0xffff; \
+        acc += (u32) >> 16;    \
+}
+
+#define SUB_CHECKSUM_32(acc, u32) { \
+        acc -= (u32) & 0xffff; \
+        acc -= (u32) >> 16;    \
+}
+
+/*
+ * We are in a "liberal" position with respect to MSS,
+ * i.e. we assume that MSS can be calculated from MTU
+ * by subtracting out only the IP and TCP header sizes
+ * without options.
+ *
+ * (RFC 879, section 7).
+ */
+#define MTU_TO_MSS(mtu) (mtu - sizeof(struct openvpn_iphdr) \
+                         - sizeof(struct openvpn_tcphdr))
+
+/*
+ * This returns an ip protocol version of packet inside tun
+ * and offset of IP header (via parameter).
+ */
+inline static int
+get_tun_ip_ver(int tunnel_type, struct buffer *buf, int *ip_hdr_offset)
+{
+    int ip_ver = -1;
+
+    /* for tun get ip version from ip header */
+    if (tunnel_type == DEV_TYPE_TUN)
+    {
+        *ip_hdr_offset = 0;
+        if (likely(BLEN(buf) >= (int) sizeof(struct openvpn_iphdr)))
+        {
+            ip_ver = OPENVPN_IPH_GET_VER(*BPTR(buf));
+        }
+    }
+    else if (tunnel_type == DEV_TYPE_TAP)
+    {
+        *ip_hdr_offset = (int)(sizeof(struct openvpn_ethhdr));
+        /* for tap get ip version from eth header */
+        if (likely(BLEN(buf) >= *ip_hdr_offset))
+        {
+            const struct openvpn_ethhdr *eh = (const struct openvpn_ethhdr *) BPTR(buf);
+            uint16_t proto = ntohs(eh->proto);
+            if (proto == OPENVPN_ETH_P_IPV6)
+            {
+                ip_ver = 6;
+            }
+            else if (proto == OPENVPN_ETH_P_IPV4)
+            {
+                ip_ver = 4;
+            }
+        }
+    }
+
+    return ip_ver;
+}
+
+/*
+ * If raw tunnel packet is IPv4 or IPv6, return true and increment
+ * buffer offset to start of IP header.
+ */
+bool is_ipv4(int tunnel_type, struct buffer *buf);
+
+bool is_ipv6(int tunnel_type, struct buffer *buf);
+
+#ifdef PACKET_TRUNCATION_CHECK
+void ipv4_packet_size_verify(const uint8_t *data,
+                             const int size,
+                             const int tunnel_type,
+                             const char
+                             *prefix,
+                             counter_type *errors);
+
+#endif
+
+#endif /* ifndef PROTO_H */
diff --git a/src/openvpn/proxy.c b/src/openvpn/proxy.c
new file mode 100644
index 0000000..afcca86
--- /dev/null
+++ b/src/openvpn/proxy.c
@@ -0,0 +1,1091 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "misc.h"
+#include "crypto.h"
+#include "win32.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "proxy.h"
+#include "base64.h"
+#include "httpdigest.h"
+#include "ntlm.h"
+#include "memdbg.h"
+#include "forward.h"
+
+#define UP_TYPE_PROXY        "HTTP Proxy"
+
+struct http_proxy_options *
+init_http_proxy_options_once(struct http_proxy_options **hpo,
+                             struct gc_arena *gc)
+{
+    if (!*hpo)
+    {
+        ALLOC_OBJ_CLEAR_GC(*hpo, struct http_proxy_options, gc);
+        /* http proxy defaults */
+        (*hpo)->http_version = "1.0";
+    }
+    return *hpo;
+}
+
+
+/* cached proxy username/password */
+static struct user_pass static_proxy_user_pass;
+
+static bool
+recv_line(socket_descriptor_t sd,
+          char *buf,
+          int len,
+          const int timeout_sec,
+          const bool verbose,
+          struct buffer *lookahead,
+          volatile int *signal_received)
+{
+    struct buffer la;
+    int lastc = 0;
+
+    CLEAR(la);
+    if (lookahead)
+    {
+        la = *lookahead;
+    }
+
+    while (true)
+    {
+        int status;
+        ssize_t size;
+        fd_set reads;
+        struct timeval tv;
+        uint8_t c;
+
+        if (buf_defined(&la))
+        {
+            ASSERT(buf_init(&la, 0));
+        }
+
+        FD_ZERO(&reads);
+        openvpn_fd_set(sd, &reads);
+        tv.tv_sec = timeout_sec;
+        tv.tv_usec = 0;
+
+        status = select(sd + 1, &reads, NULL, NULL, &tv);
+
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            goto error;
+        }
+
+        /* timeout? */
+        if (status == 0)
+        {
+            if (verbose)
+            {
+                msg(D_LINK_ERRORS | M_ERRNO, "recv_line: TCP port read timeout expired");
+            }
+            goto error;
+        }
+
+        /* error */
+        if (status < 0)
+        {
+            if (verbose)
+            {
+                msg(D_LINK_ERRORS | M_ERRNO, "recv_line: TCP port read failed on select()");
+            }
+            goto error;
+        }
+
+        /* read single char */
+        size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+        /* error? */
+        if (size != 1)
+        {
+            if (verbose)
+            {
+                msg(D_LINK_ERRORS | M_ERRNO, "recv_line: TCP port read failed on recv()");
+            }
+            goto error;
+        }
+
+#if 0
+        if (isprint(c))
+        {
+            msg(M_INFO, "PROXY: read '%c' (%d)", c, (int)c);
+        }
+        else
+        {
+            msg(M_INFO, "PROXY: read (%d)", (int)c);
+        }
+#endif
+
+        /* store char in buffer */
+        if (len > 1)
+        {
+            *buf++ = c;
+            --len;
+        }
+
+        /* also store char in lookahead buffer */
+        if (buf_defined(&la))
+        {
+            buf_write_u8(&la, c);
+            if (!isprint(c) && !isspace(c)) /* not ascii? */
+            {
+                if (verbose)
+                {
+                    msg(D_LINK_ERRORS | M_ERRNO, "recv_line: Non-ASCII character (%d) read on recv()", (int)c);
+                }
+                *lookahead = la;
+                return false;
+            }
+        }
+
+        /* end of line? */
+        if (lastc == '\r' && c == '\n')
+        {
+            break;
+        }
+
+        lastc = c;
+    }
+
+    /* append trailing null */
+    if (len > 0)
+    {
+        *buf++ = '\0';
+    }
+
+    return true;
+
+error:
+    return false;
+}
+
+static bool
+send_line(socket_descriptor_t sd,
+          const char *buf)
+{
+    const ssize_t size = send(sd, buf, strlen(buf), MSG_NOSIGNAL);
+    if (size != (ssize_t) strlen(buf))
+    {
+        msg(D_LINK_ERRORS | M_ERRNO, "send_line: TCP port write failed on send()");
+        return false;
+    }
+    return true;
+}
+
+static bool
+send_line_crlf(socket_descriptor_t sd,
+               const char *src)
+{
+    bool ret;
+
+    struct buffer buf = alloc_buf(strlen(src) + 3);
+    ASSERT(buf_write(&buf, src, strlen(src)));
+    ASSERT(buf_write(&buf, "\r\n", 3));
+    ret = send_line(sd, BSTR(&buf));
+    free_buf(&buf);
+    return ret;
+}
+
+static bool
+send_crlf(socket_descriptor_t sd)
+{
+    return send_line_crlf(sd, "");
+}
+
+uint8_t *
+make_base64_string2(const uint8_t *str, int src_len, struct gc_arena *gc)
+{
+    uint8_t *ret = NULL;
+    char *b64out = NULL;
+    ASSERT(openvpn_base64_encode((const void *)str, src_len, &b64out) >= 0);
+    ret = (uint8_t *) string_alloc(b64out, gc);
+    free(b64out);
+    return ret;
+}
+
+uint8_t *
+make_base64_string(const uint8_t *str, struct gc_arena *gc)
+{
+    return make_base64_string2(str, strlen((const char *)str), gc);
+}
+
+static const char *
+username_password_as_base64(const struct http_proxy_info *p,
+                            struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(strlen(p->up.username) + strlen(p->up.password) + 2, gc);
+    ASSERT(strlen(p->up.username) > 0);
+    buf_printf(&out, "%s:%s", p->up.username, p->up.password);
+    return (const char *)make_base64_string((const uint8_t *)BSTR(&out), gc);
+}
+
+static void
+clear_user_pass_http(void)
+{
+    purge_user_pass(&static_proxy_user_pass, true);
+}
+
+static void
+get_user_pass_http(struct http_proxy_info *p, const bool force)
+{
+    /*
+     * in case of forced (re)load, make sure the static storage is set as
+     * undefined, otherwise get_user_pass() won't try to load any credential
+     */
+    if (force)
+    {
+        clear_user_pass_http();
+    }
+
+    if (!static_proxy_user_pass.defined)
+    {
+        unsigned int flags = GET_USER_PASS_MANAGEMENT;
+        if (p->queried_creds)
+        {
+            flags |= GET_USER_PASS_PREVIOUS_CREDS_FAILED;
+        }
+        if (p->options.inline_creds)
+        {
+            flags |= GET_USER_PASS_INLINE_CREDS;
+        }
+        get_user_pass(&static_proxy_user_pass,
+                      p->options.auth_file,
+                      UP_TYPE_PROXY,
+                      flags);
+        p->queried_creds = true;
+        p->up = static_proxy_user_pass;
+    }
+}
+
+#if 0
+/* function only used in #if 0 debug statement */
+static void
+dump_residual(socket_descriptor_t sd,
+              int timeout,
+              volatile int *signal_received)
+{
+    char buf[256];
+    while (true)
+    {
+        if (!recv_line(sd, buf, sizeof(buf), timeout, true, NULL, signal_received))
+        {
+            return;
+        }
+        chomp(buf);
+        msg(D_PROXY, "PROXY HEADER: '%s'", buf);
+    }
+}
+#endif
+
+/*
+ * Extract the Proxy-Authenticate header from the stream.
+ * Consumes all headers.
+ */
+static int
+get_proxy_authenticate(socket_descriptor_t sd,
+                       int timeout,
+                       char **data,
+                       struct gc_arena *gc,
+                       volatile int *signal_received)
+{
+    char buf[256];
+    int ret = HTTP_AUTH_NONE;
+    while (true)
+    {
+        if (!recv_line(sd, buf, sizeof(buf), timeout, true, NULL, signal_received))
+        {
+            free(*data);
+            *data = NULL;
+            return HTTP_AUTH_NONE;
+        }
+        chomp(buf);
+        if (!strlen(buf))
+        {
+            return ret;
+        }
+        if (ret == HTTP_AUTH_NONE && !strncmp(buf, "Proxy-Authenticate: ", 20))
+        {
+            if (!strncmp(buf+20, "Basic ", 6))
+            {
+                msg(D_PROXY, "PROXY AUTH BASIC: '%s'", buf);
+                *data = string_alloc(buf+26, gc);
+                ret = HTTP_AUTH_BASIC;
+            }
+#if PROXY_DIGEST_AUTH
+            else if (!strncmp(buf+20, "Digest ", 7))
+            {
+                msg(D_PROXY, "PROXY AUTH DIGEST: '%s'", buf);
+                *data = string_alloc(buf+27, gc);
+                ret = HTTP_AUTH_DIGEST;
+            }
+#endif
+#if NTLM
+            else if (!strncmp(buf+20, "NTLM", 4))
+            {
+                msg(D_PROXY, "PROXY AUTH NTLM: '%s'", buf);
+                *data = NULL;
+                ret = HTTP_AUTH_NTLM;
+            }
+#endif
+        }
+    }
+}
+
+static void
+store_proxy_authenticate(struct http_proxy_info *p, char *data)
+{
+    if (p->proxy_authenticate)
+    {
+        free(p->proxy_authenticate);
+    }
+    p->proxy_authenticate = data;
+}
+
+/*
+ * Parse out key/value pairs from Proxy-Authenticate string.
+ * Return true on success, or false on parse failure.
+ */
+static bool
+get_key_value(const char *str,       /* source string */
+              char *key,             /* key stored here */
+              char *value,           /* value stored here */
+              int max_key_len,
+              int max_value_len,
+              const char **endptr)   /* next search position */
+{
+    int c;
+    bool starts_with_quote = false;
+    bool escape = false;
+
+    for (c = max_key_len-1; (*str && (*str != '=') && c--); )
+    {
+        *key++ = *str++;
+    }
+    *key = '\0';
+
+    if ('=' != *str++)
+    {
+        /* no key/value found */
+        return false;
+    }
+
+    if ('\"' == *str)
+    {
+        /* quoted string */
+        str++;
+        starts_with_quote = true;
+    }
+
+    for (c = max_value_len-1; *str && c--; str++)
+    {
+        switch (*str)
+        {
+            case '\\':
+                if (!escape)
+                {
+                    /* possibly the start of an escaped quote */
+                    escape = true;
+                    *value++ = '\\'; /* even though this is an escape character, we still
+                                      * store it as-is in the target buffer */
+                    continue;
+                }
+                break;
+
+            case ',':
+                if (!starts_with_quote)
+                {
+                    /* this signals the end of the value if we didn't get a starting quote
+                     * and then we do "sloppy" parsing */
+                    c = 0; /* the end */
+                    continue;
+                }
+                break;
+
+            case '\r':
+            case '\n':
+                /* end of string */
+                c = 0;
+                continue;
+
+            case '\"':
+                if (!escape && starts_with_quote)
+                {
+                    /* end of string */
+                    c = 0;
+                    continue;
+                }
+                break;
+        }
+        escape = false;
+        *value++ = *str;
+    }
+    *value = '\0';
+
+    *endptr = str;
+
+    return true; /* success */
+}
+
+static char *
+get_pa_var(const char *key, const char *pa, struct gc_arena *gc)
+{
+    char k[64];
+    char v[256];
+    const char *content = pa;
+
+    while (true)
+    {
+        const int status = get_key_value(content, k, v, sizeof(k), sizeof(v), &content);
+        if (status)
+        {
+            if (!strcmp(key, k))
+            {
+                return string_alloc(v, gc);
+            }
+        }
+        else
+        {
+            return NULL;
+        }
+
+        /* advance to start of next key */
+        if (*content == ',')
+        {
+            ++content;
+        }
+        while (*content && isspace(*content))
+        {
+            ++content;
+        }
+    }
+}
+
+struct http_proxy_info *
+http_proxy_new(const struct http_proxy_options *o)
+{
+    struct http_proxy_info *p;
+
+    if (!o || !o->server)
+    {
+        msg(M_FATAL, "HTTP_PROXY: server not specified");
+    }
+
+    ASSERT( o->port);
+
+    ALLOC_OBJ_CLEAR(p, struct http_proxy_info);
+    p->options = *o;
+
+    /* parse authentication method */
+    p->auth_method = HTTP_AUTH_NONE;
+    if (o->auth_method_string)
+    {
+        if (!strcmp(o->auth_method_string, "none"))
+        {
+            p->auth_method = HTTP_AUTH_NONE;
+        }
+        else if (!strcmp(o->auth_method_string, "basic"))
+        {
+            p->auth_method = HTTP_AUTH_BASIC;
+        }
+#if NTLM
+        else if (!strcmp(o->auth_method_string, "ntlm"))
+        {
+            p->auth_method = HTTP_AUTH_NTLM;
+        }
+        else if (!strcmp(o->auth_method_string, "ntlm2"))
+        {
+            p->auth_method = HTTP_AUTH_NTLM2;
+        }
+#endif
+        else
+        {
+            msg(M_FATAL, "ERROR: unknown HTTP authentication method: '%s'",
+                o->auth_method_string);
+        }
+    }
+
+    /* only basic and NTLM/NTLMv2 authentication supported so far */
+    if (p->auth_method == HTTP_AUTH_BASIC || p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2)
+    {
+        get_user_pass_http(p, true);
+    }
+
+#if !NTLM
+    if (p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2)
+    {
+        msg(M_FATAL, "Sorry, this version of " PACKAGE_NAME " was built without NTLM Proxy support.");
+    }
+#endif
+
+    p->defined = true;
+    return p;
+}
+
+void
+http_proxy_close(struct http_proxy_info *hp)
+{
+    free(hp);
+}
+
+static bool
+add_proxy_headers(struct http_proxy_info *p,
+                  socket_descriptor_t sd, /* already open to proxy */
+                  const char *host,       /* openvpn server remote */
+                  const char *port        /* openvpn server port */
+                  )
+{
+    char buf[512];
+    int i;
+    bool host_header_sent = false;
+
+    /*
+     * Send custom headers if provided
+     * If content is NULL the whole header is in name
+     * Also remember if we already sent a Host: header
+     */
+    for  (i = 0; i < MAX_CUSTOM_HTTP_HEADER && p->options.custom_headers[i].name; i++)
+    {
+        if (p->options.custom_headers[i].content)
+        {
+            openvpn_snprintf(buf, sizeof(buf), "%s: %s",
+                             p->options.custom_headers[i].name,
+                             p->options.custom_headers[i].content);
+            if (!strcasecmp(p->options.custom_headers[i].name, "Host"))
+            {
+                host_header_sent = true;
+            }
+        }
+        else
+        {
+            openvpn_snprintf(buf, sizeof(buf), "%s",
+                             p->options.custom_headers[i].name);
+            if (!strncasecmp(p->options.custom_headers[i].name, "Host:", 5))
+            {
+                host_header_sent = true;
+            }
+        }
+
+        msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+        if (!send_line_crlf(sd, buf))
+        {
+            return false;
+        }
+    }
+
+    if (!host_header_sent)
+    {
+        openvpn_snprintf(buf, sizeof(buf), "Host: %s", host);
+        msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+        if (!send_line_crlf(sd, buf))
+        {
+            return false;
+        }
+    }
+
+    /* send User-Agent string if provided */
+    if (p->options.user_agent)
+    {
+        openvpn_snprintf(buf, sizeof(buf), "User-Agent: %s",
+                         p->options.user_agent);
+        msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+        if (!send_line_crlf(sd, buf))
+        {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+
+bool
+establish_http_proxy_passthru(struct http_proxy_info *p,
+                              socket_descriptor_t sd,  /* already open to proxy */
+                              const char *host,        /* openvpn server remote */
+                              const char *port,          /* openvpn server port */
+                              struct event_timeout *server_poll_timeout,
+                              struct buffer *lookahead,
+                              volatile int *signal_received)
+{
+    struct gc_arena gc = gc_new();
+    char buf[512];
+    char buf2[129];
+    char get[80];
+    int status;
+    int nparms;
+    bool ret = false;
+    bool processed = false;
+
+    /* get user/pass if not previously given */
+    if (p->auth_method == HTTP_AUTH_BASIC
+        || p->auth_method == HTTP_AUTH_DIGEST
+        || p->auth_method == HTTP_AUTH_NTLM)
+    {
+        get_user_pass_http(p, false);
+    }
+
+    /* are we being called again after getting the digest server nonce in the previous transaction? */
+    if (p->auth_method == HTTP_AUTH_DIGEST && p->proxy_authenticate)
+    {
+        nparms = 1;
+        status = 407;
+    }
+    else
+    {
+        /* format HTTP CONNECT message */
+        openvpn_snprintf(buf, sizeof(buf), "CONNECT %s:%s HTTP/%s",
+                         host,
+                         port,
+                         p->options.http_version);
+
+        msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+
+        /* send HTTP CONNECT message to proxy */
+        if (!send_line_crlf(sd, buf))
+        {
+            goto error;
+        }
+
+        if (!add_proxy_headers(p, sd, host, port))
+        {
+            goto error;
+        }
+
+        /* auth specified? */
+        switch (p->auth_method)
+        {
+            case HTTP_AUTH_NONE:
+                break;
+
+            case HTTP_AUTH_BASIC:
+                openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: Basic %s",
+                                 username_password_as_base64(p, &gc));
+                msg(D_PROXY, "Attempting Basic Proxy-Authorization");
+                dmsg(D_SHOW_KEYS, "Send to HTTP proxy: '%s'", buf);
+                if (!send_line_crlf(sd, buf))
+                {
+                    goto error;
+                }
+                break;
+
+#if NTLM
+            case HTTP_AUTH_NTLM:
+            case HTTP_AUTH_NTLM2:
+                /* keep-alive connection */
+                openvpn_snprintf(buf, sizeof(buf), "Proxy-Connection: Keep-Alive");
+                if (!send_line_crlf(sd, buf))
+                {
+                    goto error;
+                }
+
+                openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: NTLM %s",
+                                 ntlm_phase_1(p, &gc));
+                msg(D_PROXY, "Attempting NTLM Proxy-Authorization phase 1");
+                dmsg(D_SHOW_KEYS, "Send to HTTP proxy: '%s'", buf);
+                if (!send_line_crlf(sd, buf))
+                {
+                    goto error;
+                }
+                break;
+#endif
+
+            default:
+                ASSERT(0);
+        }
+
+        /* send empty CR, LF */
+        if (!send_crlf(sd))
+        {
+            goto error;
+        }
+
+        /* receive reply from proxy */
+        if (!recv_line(sd, buf, sizeof(buf), get_server_poll_remaining_time(server_poll_timeout), true, NULL, signal_received))
+        {
+            goto error;
+        }
+
+        /* remove trailing CR, LF */
+        chomp(buf);
+
+        msg(D_PROXY, "HTTP proxy returned: '%s'", buf);
+
+        /* parse return string */
+        nparms = sscanf(buf, "%*s %d", &status);
+
+    }
+
+    /* check for a "407 Proxy Authentication Required" response */
+    while (nparms >= 1 && status == 407)
+    {
+        msg(D_PROXY, "Proxy requires authentication");
+
+        if (p->auth_method == HTTP_AUTH_BASIC && !processed)
+        {
+            processed = true;
+        }
+        else if ((p->auth_method == HTTP_AUTH_NTLM || p->auth_method == HTTP_AUTH_NTLM2) && !processed) /* check for NTLM */
+        {
+#if NTLM
+            /* look for the phase 2 response */
+
+            while (true)
+            {
+                if (!recv_line(sd, buf, sizeof(buf), get_server_poll_remaining_time(server_poll_timeout), true, NULL, signal_received))
+                {
+                    goto error;
+                }
+                chomp(buf);
+                msg(D_PROXY, "HTTP proxy returned: '%s'", buf);
+
+                openvpn_snprintf(get, sizeof get, "%%*s NTLM %%%ds", (int) sizeof(buf2) - 1);
+                nparms = sscanf(buf, get, buf2);
+                buf2[128] = 0; /* we only need the beginning - ensure it's null terminated. */
+
+                /* check for "Proxy-Authenticate: NTLM TlRM..." */
+                if (nparms == 1)
+                {
+                    /* parse buf2 */
+                    msg(D_PROXY, "auth string: '%s'", buf2);
+                    break;
+                }
+            }
+            /* if we are here then auth string was got */
+            msg(D_PROXY, "Received NTLM Proxy-Authorization phase 2 response");
+
+            /* receive and discard everything else */
+            while (recv_line(sd, NULL, 0, 2, true, NULL, signal_received))
+            {
+            }
+
+            /* now send the phase 3 reply */
+
+            /* format HTTP CONNECT message */
+            openvpn_snprintf(buf, sizeof(buf), "CONNECT %s:%s HTTP/%s",
+                             host,
+                             port,
+                             p->options.http_version);
+
+            msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+
+            /* send HTTP CONNECT message to proxy */
+            if (!send_line_crlf(sd, buf))
+            {
+                goto error;
+            }
+
+            /* keep-alive connection */
+            openvpn_snprintf(buf, sizeof(buf), "Proxy-Connection: Keep-Alive");
+            if (!send_line_crlf(sd, buf))
+            {
+                goto error;
+            }
+
+            /* send HOST etc, */
+            if (!add_proxy_headers(p, sd, host, port))
+            {
+                goto error;
+            }
+
+            msg(D_PROXY, "Attempting NTLM Proxy-Authorization phase 3");
+            {
+                const char *np3 = ntlm_phase_3(p, buf2, &gc);
+                if (!np3)
+                {
+                    msg(D_PROXY, "NTLM Proxy-Authorization phase 3 failed: received corrupted data from proxy server");
+                    goto error;
+                }
+                openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: NTLM %s", np3);
+            }
+
+            msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+            if (!send_line_crlf(sd, buf))
+            {
+                goto error;
+            }
+            /* ok so far... */
+            /* send empty CR, LF */
+            if (!send_crlf(sd))
+            {
+                goto error;
+            }
+
+            /* receive reply from proxy */
+            if (!recv_line(sd, buf, sizeof(buf), get_server_poll_remaining_time(server_poll_timeout), true, NULL, signal_received))
+            {
+                goto error;
+            }
+
+            /* remove trailing CR, LF */
+            chomp(buf);
+
+            msg(D_PROXY, "HTTP proxy returned: '%s'", buf);
+
+            /* parse return string */
+            nparms = sscanf(buf, "%*s %d", &status);
+            processed = true;
+#endif /* if NTLM */
+        }
+#if PROXY_DIGEST_AUTH
+        else if (p->auth_method == HTTP_AUTH_DIGEST && !processed)
+        {
+            char *pa = p->proxy_authenticate;
+            const int method = p->auth_method;
+            ASSERT(pa);
+
+            if (method == HTTP_AUTH_DIGEST)
+            {
+                const char *http_method = "CONNECT";
+                const char *nonce_count = "00000001";
+                const char *qop = "auth";
+                const char *username = p->up.username;
+                const char *password = p->up.password;
+                char *opaque_kv = "";
+                char uri[128];
+                uint8_t cnonce_raw[8];
+                uint8_t *cnonce;
+                HASHHEX session_key;
+                HASHHEX response;
+
+                const char *realm = get_pa_var("realm", pa, &gc);
+                const char *nonce = get_pa_var("nonce", pa, &gc);
+                const char *algor = get_pa_var("algorithm", pa, &gc);
+                const char *opaque = get_pa_var("opaque", pa, &gc);
+
+                if ( !realm || !nonce )
+                {
+                    msg(D_LINK_ERRORS, "HTTP proxy: digest auth failed, malformed response "
+                            "from server: realm= or nonce= missing" );
+                    goto error;
+                }
+
+                /* generate a client nonce */
+                ASSERT(rand_bytes(cnonce_raw, sizeof(cnonce_raw)));
+                cnonce = make_base64_string2(cnonce_raw, sizeof(cnonce_raw), &gc);
+
+
+                /* build the digest response */
+                openvpn_snprintf(uri, sizeof(uri), "%s:%s",
+                                 host,
+                                 port);
+
+                if (opaque)
+                {
+                    const int len = strlen(opaque)+16;
+                    opaque_kv = gc_malloc(len, false, &gc);
+                    openvpn_snprintf(opaque_kv, len, ", opaque=\"%s\"", opaque);
+                }
+
+                DigestCalcHA1(algor,
+                              username,
+                              realm,
+                              password,
+                              nonce,
+                              (char *)cnonce,
+                              session_key);
+                DigestCalcResponse(session_key,
+                                   nonce,
+                                   nonce_count,
+                                   (char *)cnonce,
+                                   qop,
+                                   http_method,
+                                   uri,
+                                   NULL,
+                                   response);
+
+                /* format HTTP CONNECT message */
+                openvpn_snprintf(buf, sizeof(buf), "%s %s HTTP/%s",
+                                 http_method,
+                                 uri,
+                                 p->options.http_version);
+
+                msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+
+                /* send HTTP CONNECT message to proxy */
+                if (!send_line_crlf(sd, buf))
+                {
+                    goto error;
+                }
+
+                /* send HOST etc, */
+                if (!add_proxy_headers(p, sd, host, port))
+                {
+                    goto error;
+                }
+
+                /* send digest response */
+                openvpn_snprintf(buf, sizeof(buf), "Proxy-Authorization: Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", qop=%s, nc=%s, cnonce=\"%s\", response=\"%s\"%s",
+                                 username,
+                                 realm,
+                                 nonce,
+                                 uri,
+                                 qop,
+                                 nonce_count,
+                                 cnonce,
+                                 response,
+                                 opaque_kv
+                                 );
+                msg(D_PROXY, "Send to HTTP proxy: '%s'", buf);
+                if (!send_line_crlf(sd, buf))
+                {
+                    goto error;
+                }
+                if (!send_crlf(sd))
+                {
+                    goto error;
+                }
+
+                /* receive reply from proxy */
+                if (!recv_line(sd, buf, sizeof(buf), get_server_poll_remaining_time(server_poll_timeout), true, NULL, signal_received))
+                {
+                    goto error;
+                }
+
+                /* remove trailing CR, LF */
+                chomp(buf);
+
+                msg(D_PROXY, "HTTP proxy returned: '%s'", buf);
+
+                /* parse return string */
+                nparms = sscanf(buf, "%*s %d", &status);
+                processed = true;
+            }
+            else
+            {
+                msg(D_PROXY, "HTTP proxy: digest method not supported");
+                goto error;
+            }
+        }
+#endif /* if PROXY_DIGEST_AUTH */
+        else if (p->options.auth_retry)
+        {
+            /* figure out what kind of authentication the proxy needs */
+            char *pa = NULL;
+            const int method = get_proxy_authenticate(sd,
+                                                      get_server_poll_remaining_time(server_poll_timeout),
+                                                      &pa,
+                                                      NULL,
+                                                      signal_received);
+            if (method != HTTP_AUTH_NONE)
+            {
+                if (pa)
+                {
+                    msg(D_PROXY, "HTTP proxy authenticate '%s'", pa);
+                }
+                if (p->options.auth_retry == PAR_NCT && method == HTTP_AUTH_BASIC)
+                {
+                    msg(D_PROXY, "HTTP proxy: support for basic auth and other cleartext proxy auth methods is disabled");
+                    free(pa);
+                    goto error;
+                }
+                p->auth_method = method;
+                store_proxy_authenticate(p, pa);
+                ret = true;
+                goto done;
+            }
+            else
+            {
+                msg(D_PROXY, "HTTP proxy: do not recognize the authentication method required by proxy");
+                free(pa);
+                goto error;
+            }
+        }
+        else
+        {
+            if (!processed)
+            {
+                msg(D_PROXY, "HTTP proxy: no support for proxy authentication method");
+            }
+            goto error;
+        }
+
+        /* clear state */
+        if (p->options.auth_retry)
+        {
+            clear_user_pass_http();
+        }
+        store_proxy_authenticate(p, NULL);
+    }
+
+    /* check return code, success = 200 */
+    if (nparms < 1 || status != 200)
+    {
+        msg(D_LINK_ERRORS, "HTTP proxy returned bad status");
+#if 0
+        /* DEBUGGING -- show a multi-line HTTP error response */
+        dump_residual(sd, get_server_poll_remaining_time(server_poll_timeout), signal_received);
+#endif
+        goto error;
+    }
+
+    /* SUCCESS */
+
+    /* receive line from proxy and discard */
+    if (!recv_line(sd, NULL, 0, get_server_poll_remaining_time(server_poll_timeout), true, NULL, signal_received))
+    {
+        goto error;
+    }
+
+    /*
+     * Toss out any extraneous chars, but don't throw away the
+     * start of the OpenVPN data stream (put it in lookahead).
+     */
+    while (recv_line(sd, NULL, 0, 2, false, lookahead, signal_received))
+    {
+    }
+
+    /* reset queried_creds so that we don't think that the next creds request is due to an auth error */
+    p->queried_creds = false;
+
+#if 0
+    if (lookahead && BLEN(lookahead))
+    {
+        msg(M_INFO, "HTTP PROXY: lookahead: %s", format_hex(BPTR(lookahead), BLEN(lookahead), 0));
+    }
+#endif
+
+done:
+    gc_free(&gc);
+    return ret;
+
+error:
+    if (!*signal_received)
+    {
+        *signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- HTTP proxy error */
+    }
+    gc_free(&gc);
+    return ret;
+}
diff --git a/src/openvpn/proxy.h b/src/openvpn/proxy.h
new file mode 100644
index 0000000..707f7fa
--- /dev/null
+++ b/src/openvpn/proxy.h
@@ -0,0 +1,95 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PROXY_H
+#define PROXY_H
+
+#include "buffer.h"
+#include "misc.h"
+
+/* HTTP CONNECT authentication methods */
+#define HTTP_AUTH_NONE   0
+#define HTTP_AUTH_BASIC  1
+#define HTTP_AUTH_DIGEST 2
+#define HTTP_AUTH_NTLM   3
+#define HTTP_AUTH_NTLM2  4
+#define HTTP_AUTH_N      5 /* number of HTTP_AUTH methods */
+
+struct http_custom_header {
+    const char *name;
+    const char *content;
+};
+
+#define MAX_CUSTOM_HTTP_HEADER 10
+struct http_proxy_options {
+    const char *server;
+    const char *port;
+
+#define PAR_NO  0   /* don't support any auth retries */
+#define PAR_ALL 1   /* allow all proxy auth protocols */
+#define PAR_NCT 2   /* disable cleartext proxy auth protocols */
+    int auth_retry;
+
+    const char *auth_method_string;
+    const char *auth_file;
+    const char *http_version;
+    const char *user_agent;
+    struct http_custom_header custom_headers[MAX_CUSTOM_HTTP_HEADER];
+    bool inline_creds;
+};
+
+struct http_proxy_options_simple {
+    const char *server;
+    const char *port;
+    int auth_retry;
+};
+
+struct http_proxy_info {
+    bool defined;
+    int auth_method;
+    struct http_proxy_options options;
+    struct user_pass up;
+    char *proxy_authenticate;
+    bool queried_creds;
+};
+
+struct http_proxy_options *init_http_proxy_options_once(struct http_proxy_options **hpo,
+                                                        struct gc_arena *gc);
+
+struct http_proxy_info *http_proxy_new(const struct http_proxy_options *o);
+
+void http_proxy_close(struct http_proxy_info *hp);
+
+bool establish_http_proxy_passthru(struct http_proxy_info *p,
+                                   socket_descriptor_t sd,  /* already open to proxy */
+                                   const char *host,        /* openvpn server remote */
+                                   const char *port,          /* openvpn server port */
+                                   struct event_timeout *server_poll_timeout,
+                                   struct buffer *lookahead,
+                                   volatile int *signal_received);
+
+uint8_t *make_base64_string2(const uint8_t *str, int str_len, struct gc_arena *gc);
+
+uint8_t *make_base64_string(const uint8_t *str, struct gc_arena *gc);
+
+#endif /* PROXY_H */
diff --git a/src/openvpn/ps.c b/src/openvpn/ps.c
new file mode 100644
index 0000000..25ab374
--- /dev/null
+++ b/src/openvpn/ps.c
@@ -0,0 +1,1014 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if PORT_SHARE
+
+#include "event.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "crypto.h"
+#include "ps.h"
+
+#include "memdbg.h"
+
+struct port_share *port_share = NULL; /* GLOBAL */
+
+/* size of i/o buffers */
+#define PROXY_CONNECTION_BUFFER_SIZE 1500
+
+/* Command codes for foreground -> background communication */
+#define COMMAND_REDIRECT 10
+#define COMMAND_EXIT     11
+
+/* Response codes for background -> foreground communication */
+#define RESPONSE_INIT_SUCCEEDED   20
+#define RESPONSE_INIT_FAILED      21
+
+/*
+ * Return values for proxy_connection_io functions
+ */
+
+#define IOSTAT_EAGAIN_ON_READ   0 /* recv returned EAGAIN */
+#define IOSTAT_EAGAIN_ON_WRITE  1 /* send returned EAGAIN */
+#define IOSTAT_READ_ERROR       2 /* the other end of our read socket (pc) was closed */
+#define IOSTAT_WRITE_ERROR      3 /* the other end of our write socket (pc->counterpart) was closed */
+#define IOSTAT_GOOD             4 /* nothing to report */
+
+/*
+ * A foreign (non-OpenVPN) connection we are proxying,
+ * usually HTTPS
+ */
+struct proxy_connection {
+    bool defined;
+    struct proxy_connection *next;
+    struct proxy_connection *counterpart;
+    struct buffer buf;
+    bool buffer_initial;
+    int rwflags;
+    int sd;
+    char *jfn;
+};
+
+#if 0
+static const char *
+headc(const struct buffer *buf)
+{
+    static char foo[16];
+    strncpy(foo, BSTR(buf), 15);
+    foo[15] = 0;
+    return foo;
+}
+#endif
+
+static inline void
+close_socket_if_defined(const socket_descriptor_t sd)
+{
+    if (socket_defined(sd))
+    {
+        openvpn_close_socket(sd);
+    }
+}
+
+/*
+ * Close most of parent's fds.
+ * Keep stdin/stdout/stderr, plus one
+ * other fd which is presumed to be
+ * our pipe back to parent.
+ * Admittedly, a bit of a kludge,
+ * but posix doesn't give us a kind
+ * of FD_CLOEXEC which will stop
+ * fds from crossing a fork().
+ */
+static void
+close_fds_except(int keep)
+{
+    socket_descriptor_t i;
+    closelog();
+    for (i = 3; i <= 100; ++i)
+    {
+        if (i != keep)
+        {
+            openvpn_close_socket(i);
+        }
+    }
+}
+
+/*
+ * Usually we ignore signals, because our parent will
+ * deal with them.
+ */
+static void
+set_signals(void)
+{
+    signal(SIGTERM, SIG_DFL);
+
+    signal(SIGINT, SIG_IGN);
+    signal(SIGHUP, SIG_IGN);
+    signal(SIGUSR1, SIG_IGN);
+    signal(SIGUSR2, SIG_IGN);
+    signal(SIGPIPE, SIG_IGN);
+}
+
+/*
+ * Socket read/write functions.
+ */
+
+static int
+recv_control(const socket_descriptor_t fd)
+{
+    unsigned char c;
+    const ssize_t size = read(fd, &c, sizeof(c));
+    if (size == sizeof(c))
+    {
+        return c;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+static int
+send_control(const socket_descriptor_t fd, int code)
+{
+    unsigned char c = (unsigned char) code;
+    const ssize_t size = write(fd, &c, sizeof(c));
+    if (size == sizeof(c))
+    {
+        return (int) size;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+static int
+cmsg_size(void)
+{
+    return CMSG_SPACE(sizeof(socket_descriptor_t));
+}
+
+/*
+ * Send a command (char), data (head), and a file descriptor (sd_send) to a local process
+ * over unix socket sd.  Unfortunately, there's no portable way to send file descriptors
+ * to other processes, so this code, as well as its analog (control_message_from_parent below),
+ * is Linux-specific. This function runs in the context of the main process and is used to
+ * send commands, data, and file descriptors to the background process.
+ */
+static void
+port_share_sendmsg(const socket_descriptor_t sd,
+                   const char command,
+                   const struct buffer *head,
+                   const socket_descriptor_t sd_send)
+{
+    if (socket_defined(sd))
+    {
+        struct msghdr mesg;
+        struct cmsghdr *h;
+        struct iovec iov[2];
+        socket_descriptor_t sd_null[2] = { SOCKET_UNDEFINED, SOCKET_UNDEFINED };
+        char cmd;
+        ssize_t status;
+
+        dmsg(D_PS_PROXY_DEBUG, "PORT SHARE: sendmsg sd=%d len=%d",
+             (int)sd_send,
+             head ? BLEN(head) : -1);
+
+        CLEAR(mesg);
+
+        cmd = command;
+
+        iov[0].iov_base = &cmd;
+        iov[0].iov_len = sizeof(cmd);
+        mesg.msg_iovlen = 1;
+
+        if (head)
+        {
+            iov[1].iov_base = BPTR(head);
+            iov[1].iov_len = BLEN(head);
+            mesg.msg_iovlen = 2;
+        }
+
+        mesg.msg_iov = iov;
+
+        mesg.msg_controllen = cmsg_size();
+        mesg.msg_control = (char *) malloc(mesg.msg_controllen);
+        check_malloc_return(mesg.msg_control);
+        mesg.msg_flags = 0;
+
+        h = CMSG_FIRSTHDR(&mesg);
+        h->cmsg_level = SOL_SOCKET;
+        h->cmsg_type = SCM_RIGHTS;
+        h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
+
+        if (socket_defined(sd_send))
+        {
+            memcpy(CMSG_DATA(h), &sd_send, sizeof(sd_send));
+        }
+        else
+        {
+            socketpair(PF_UNIX, SOCK_DGRAM, 0, sd_null);
+            memcpy(CMSG_DATA(h), &sd_null[0], sizeof(sd_null[0]));
+        }
+
+        status = sendmsg(sd, &mesg, MSG_NOSIGNAL);
+        if (status == -1)
+        {
+            msg(M_WARN|M_ERRNO, "PORT SHARE: sendmsg failed -- unable to communicate with background process (%d,%d,%d,%d)",
+                sd, sd_send, sd_null[0], sd_null[1]
+                );
+        }
+
+        close_socket_if_defined(sd_null[0]);
+        close_socket_if_defined(sd_null[1]);
+        free(mesg.msg_control);
+    }
+}
+
+static void
+proxy_entry_close_sd(struct proxy_connection *pc, struct event_set *es)
+{
+    if (pc->defined && socket_defined(pc->sd))
+    {
+        dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: delete sd=%d", (int)pc->sd);
+        if (es)
+        {
+            event_del(es, pc->sd);
+        }
+        openvpn_close_socket(pc->sd);
+        pc->sd = SOCKET_UNDEFINED;
+    }
+}
+
+/*
+ * Mark a proxy entry and its counterpart for close.
+ */
+static void
+proxy_entry_mark_for_close(struct proxy_connection *pc, struct event_set *es)
+{
+    if (pc->defined)
+    {
+        struct proxy_connection *cp = pc->counterpart;
+        proxy_entry_close_sd(pc, es);
+        free_buf(&pc->buf);
+        pc->buffer_initial = false;
+        pc->rwflags = 0;
+        pc->defined = false;
+        if (pc->jfn)
+        {
+            unlink(pc->jfn);
+            free(pc->jfn);
+            pc->jfn = NULL;
+        }
+        if (cp && cp->defined && cp->counterpart == pc)
+        {
+            proxy_entry_mark_for_close(cp, es);
+        }
+    }
+}
+
+/*
+ * Run through the proxy entry list and delete all entries marked
+ * for close.
+ */
+static void
+proxy_list_housekeeping(struct proxy_connection **list)
+{
+    if (list)
+    {
+        struct proxy_connection *prev = NULL;
+        struct proxy_connection *pc = *list;
+
+        while (pc)
+        {
+            struct proxy_connection *next = pc->next;
+            if (!pc->defined)
+            {
+                free(pc);
+                if (prev)
+                {
+                    prev->next = next;
+                }
+                else
+                {
+                    *list = next;
+                }
+            }
+            else
+            {
+                prev = pc;
+            }
+            pc = next;
+        }
+    }
+}
+
+/*
+ * Record IP/port of client in filesystem, so that server receiving
+ * the proxy can determine true client origin.
+ */
+static void
+journal_add(const char *journal_dir, struct proxy_connection *pc, struct proxy_connection *cp)
+{
+    struct gc_arena gc = gc_new();
+    struct openvpn_sockaddr from, to;
+    socklen_t slen, dlen;
+    int fnlen;
+    char *jfn;
+    int fd;
+
+    slen = sizeof(from.addr.sa);
+    dlen = sizeof(to.addr.sa);
+    if (!getpeername(pc->sd, (struct sockaddr *) &from.addr.sa, &slen)
+        && !getsockname(cp->sd, (struct sockaddr *) &to.addr.sa, &dlen))
+    {
+        const char *f = print_openvpn_sockaddr(&from, &gc);
+        const char *t = print_openvpn_sockaddr(&to, &gc);
+        fnlen =  strlen(journal_dir) + strlen(t) + 2;
+        jfn = (char *) malloc(fnlen);
+        check_malloc_return(jfn);
+        openvpn_snprintf(jfn, fnlen, "%s/%s", journal_dir, t);
+        dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: client origin %s -> %s", jfn, f);
+        fd = platform_open(jfn, O_CREAT | O_TRUNC | O_WRONLY, S_IRUSR | S_IWUSR | S_IRGRP);
+        if (fd != -1)
+        {
+            if (write(fd, f, strlen(f)) != strlen(f))
+            {
+                msg(M_WARN, "PORT SHARE: writing to journal file (%s) failed", jfn);
+            }
+            close(fd);
+            cp->jfn = jfn;
+        }
+        else
+        {
+            msg(M_WARN|M_ERRNO, "PORT SHARE: unable to write journal file in %s", jfn);
+            free(jfn);
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Cleanup function, on proxy process exit.
+ */
+static void
+proxy_list_close(struct proxy_connection **list)
+{
+    if (list)
+    {
+        struct proxy_connection *pc = *list;
+        while (pc)
+        {
+            proxy_entry_mark_for_close(pc, NULL);
+            pc = pc->next;
+        }
+        proxy_list_housekeeping(list);
+    }
+}
+
+static inline void
+proxy_connection_io_requeue(struct proxy_connection *pc, const int rwflags_new, struct event_set *es)
+{
+    if (socket_defined(pc->sd) && pc->rwflags != rwflags_new)
+    {
+        /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: requeue[%d] rwflags=%d", (int)pc->sd, rwflags_new);*/
+        event_ctl(es, pc->sd, rwflags_new, (void *)pc);
+        pc->rwflags = rwflags_new;
+    }
+}
+
+/*
+ * Create a new pair of proxy_connection entries, one for each
+ * socket file descriptor involved in the proxy.  We are given
+ * the client fd, and we should derive our own server fd by connecting
+ * to the server given by server_addr/server_port.  Return true
+ * on success and false on failure to connect to server.
+ */
+static bool
+proxy_entry_new(struct proxy_connection **list,
+                struct event_set *es,
+                const struct sockaddr_in server_addr,
+                const socket_descriptor_t sd_client,
+                struct buffer *initial_data,
+                const char *journal_dir)
+{
+    socket_descriptor_t sd_server;
+    int status;
+    struct proxy_connection *pc;
+    struct proxy_connection *cp;
+
+    /* connect to port share server */
+    if ((sd_server = socket(PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
+    {
+        msg(M_WARN|M_ERRNO, "PORT SHARE PROXY: cannot create socket");
+        return false;
+    }
+    status = openvpn_connect(sd_server,(const struct sockaddr *)  &server_addr, 5, NULL);
+    if (status)
+    {
+        msg(M_WARN, "PORT SHARE PROXY: connect to port-share server failed");
+        openvpn_close_socket(sd_server);
+        return false;
+    }
+    dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: connect to port-share server succeeded");
+
+    set_nonblock(sd_client);
+    set_nonblock(sd_server);
+
+    /* allocate 2 new proxy_connection objects */
+    ALLOC_OBJ_CLEAR(pc, struct proxy_connection);
+    ALLOC_OBJ_CLEAR(cp, struct proxy_connection);
+
+    /* client object */
+    pc->defined = true;
+    pc->next = cp;
+    pc->counterpart = cp;
+    pc->buf = *initial_data;
+    pc->buffer_initial = true;
+    pc->rwflags = EVENT_UNDEF;
+    pc->sd = sd_client;
+
+    /* server object */
+    cp->defined = true;
+    cp->next = *list;
+    cp->counterpart = pc;
+    cp->buf = alloc_buf(PROXY_CONNECTION_BUFFER_SIZE);
+    cp->buffer_initial = false;
+    cp->rwflags = EVENT_UNDEF;
+    cp->sd = sd_server;
+
+    /* add to list */
+    *list = pc;
+
+    /* add journal entry */
+    if (journal_dir)
+    {
+        journal_add(journal_dir, pc, cp);
+    }
+
+    dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: NEW CONNECTION [c=%d s=%d]", (int)sd_client, (int)sd_server);
+
+    /* set initial i/o states */
+    proxy_connection_io_requeue(pc, EVENT_READ, es);
+    proxy_connection_io_requeue(cp, EVENT_READ|EVENT_WRITE, es);
+
+    return true;
+}
+
+/*
+ * This function runs in the context of the background proxy process.
+ * Receive a control message from the parent (sent by the port_share_sendmsg
+ * function above) and act on it.  Return false if the proxy process should
+ * exit, true otherwise.
+ */
+static bool
+control_message_from_parent(const socket_descriptor_t sd_control,
+                            struct proxy_connection **list,
+                            struct event_set *es,
+                            const struct sockaddr_in server_addr,
+                            const int max_initial_buf,
+                            const char *journal_dir)
+{
+    /* this buffer needs to be large enough to handle the largest buffer
+     * that might be returned by the link_socket_read call in read_incoming_link. */
+    struct buffer buf = alloc_buf(max_initial_buf);
+
+    struct msghdr mesg;
+    struct cmsghdr *h;
+    struct iovec iov[2];
+    char command = 0;
+    ssize_t status;
+    int ret = true;
+
+    CLEAR(mesg);
+
+    iov[0].iov_base = &command;
+    iov[0].iov_len = sizeof(command);
+    iov[1].iov_base = BPTR(&buf);
+    iov[1].iov_len = BCAP(&buf);
+    mesg.msg_iov = iov;
+    mesg.msg_iovlen = 2;
+
+    mesg.msg_controllen = cmsg_size();
+    mesg.msg_control = (char *) malloc(mesg.msg_controllen);
+    check_malloc_return(mesg.msg_control);
+    mesg.msg_flags = 0;
+
+    h = CMSG_FIRSTHDR(&mesg);
+    h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
+    h->cmsg_level = SOL_SOCKET;
+    h->cmsg_type = SCM_RIGHTS;
+    static const socket_descriptor_t socket_undefined = SOCKET_UNDEFINED;
+    memcpy(CMSG_DATA(h), &socket_undefined, sizeof(socket_undefined));
+
+    status = recvmsg(sd_control, &mesg, MSG_NOSIGNAL);
+    if (status != -1)
+    {
+        if (h == NULL
+            || h->cmsg_len    != CMSG_LEN(sizeof(socket_descriptor_t))
+            || h->cmsg_level  != SOL_SOCKET
+            || h->cmsg_type   != SCM_RIGHTS)
+        {
+            msg(M_WARN, "PORT SHARE PROXY: received unknown message");
+        }
+        else
+        {
+            socket_descriptor_t received_fd;
+            memcpy(&received_fd, CMSG_DATA(h), sizeof(received_fd));
+            dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED sd=%d", (int)received_fd);
+
+            if (status >= 2 && command == COMMAND_REDIRECT)
+            {
+                buf.len = status - 1;
+                if (proxy_entry_new(list,
+                                    es,
+                                    server_addr,
+                                    received_fd,
+                                    &buf,
+                                    journal_dir))
+                {
+                    CLEAR(buf); /* we gave the buffer to proxy_entry_new */
+                }
+                else
+                {
+                    openvpn_close_socket(received_fd);
+                }
+            }
+            else if (status >= 1 && command == COMMAND_EXIT)
+            {
+                dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED COMMAND_EXIT");
+                openvpn_close_socket(received_fd); /* null socket */
+                ret = false;
+            }
+        }
+    }
+    free(mesg.msg_control);
+    free_buf(&buf);
+    return ret;
+}
+
+static int
+proxy_connection_io_recv(struct proxy_connection *pc)
+{
+    /* recv data from socket */
+    const int status = recv(pc->sd, BPTR(&pc->buf), BCAP(&pc->buf), MSG_NOSIGNAL);
+    if (status < 0)
+    {
+        return (errno == EAGAIN) ? IOSTAT_EAGAIN_ON_READ : IOSTAT_READ_ERROR;
+    }
+    else
+    {
+        if (!status)
+        {
+            return IOSTAT_READ_ERROR;
+        }
+        dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: read[%d] %d", (int)pc->sd, status);
+        pc->buf.len = status;
+    }
+    return IOSTAT_GOOD;
+}
+
+static int
+proxy_connection_io_send(struct proxy_connection *pc, int *bytes_sent)
+{
+    const socket_descriptor_t sd = pc->counterpart->sd;
+    const int status = send(sd, BPTR(&pc->buf), BLEN(&pc->buf), MSG_NOSIGNAL);
+
+    if (status < 0)
+    {
+        const int e = errno;
+        return (e == EAGAIN) ? IOSTAT_EAGAIN_ON_WRITE : IOSTAT_WRITE_ERROR;
+    }
+    else
+    {
+        *bytes_sent += status;
+        if (status != pc->buf.len)
+        {
+            dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: partial write[%d], tried=%d got=%d", (int)sd, pc->buf.len, status);
+            buf_advance(&pc->buf, status);
+            return IOSTAT_EAGAIN_ON_WRITE;
+        }
+        else
+        {
+            dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: wrote[%d] %d", (int)sd, status);
+            pc->buf.len = 0;
+            pc->buf.offset = 0;
+        }
+    }
+
+    /* realloc send buffer after initial send */
+    if (pc->buffer_initial)
+    {
+        free_buf(&pc->buf);
+        pc->buf = alloc_buf(PROXY_CONNECTION_BUFFER_SIZE);
+        pc->buffer_initial = false;
+    }
+    return IOSTAT_GOOD;
+}
+
+/*
+ * Forward data from pc to pc->counterpart.
+ */
+
+static int
+proxy_connection_io_xfer(struct proxy_connection *pc, const int max_transfer)
+{
+    int transferred = 0;
+    while (transferred < max_transfer)
+    {
+        if (!BLEN(&pc->buf))
+        {
+            const int status = proxy_connection_io_recv(pc);
+            if (status != IOSTAT_GOOD)
+            {
+                return status;
+            }
+        }
+
+        if (BLEN(&pc->buf))
+        {
+            const int status = proxy_connection_io_send(pc, &transferred);
+            if (status != IOSTAT_GOOD)
+            {
+                return status;
+            }
+        }
+    }
+    return IOSTAT_EAGAIN_ON_READ;
+}
+
+/*
+ * Decide how the receipt of an EAGAIN status should affect our next IO queueing.
+ */
+static bool
+proxy_connection_io_status(const int status, int *rwflags_pc, int *rwflags_cp)
+{
+    switch (status)
+    {
+        case IOSTAT_EAGAIN_ON_READ:
+            *rwflags_pc |= EVENT_READ;
+            *rwflags_cp &= ~EVENT_WRITE;
+            return true;
+
+        case IOSTAT_EAGAIN_ON_WRITE:
+            *rwflags_pc &= ~EVENT_READ;
+            *rwflags_cp |= EVENT_WRITE;
+            return true;
+
+        case IOSTAT_READ_ERROR:
+            return false;
+
+        case IOSTAT_WRITE_ERROR:
+            return false;
+
+        default:
+            msg(M_FATAL, "PORT SHARE PROXY: unexpected status=%d", status);
+    }
+    return false; /* NOTREACHED */
+}
+
+/*
+ * Dispatch function for forwarding data between the two socket fds involved
+ * in the proxied connection.
+ */
+static int
+proxy_connection_io_dispatch(struct proxy_connection *pc,
+                             const int rwflags,
+                             struct event_set *es)
+{
+    const int max_transfer_per_iteration = 10000;
+    struct proxy_connection *cp = pc->counterpart;
+    int rwflags_pc = pc->rwflags;
+    int rwflags_cp = cp->rwflags;
+
+    ASSERT(pc->defined && cp->defined && cp->counterpart == pc);
+
+    if (rwflags & EVENT_READ)
+    {
+        const int status = proxy_connection_io_xfer(pc, max_transfer_per_iteration);
+        if (!proxy_connection_io_status(status, &rwflags_pc, &rwflags_cp))
+        {
+            goto bad;
+        }
+    }
+    if (rwflags & EVENT_WRITE)
+    {
+        const int status = proxy_connection_io_xfer(cp, max_transfer_per_iteration);
+        if (!proxy_connection_io_status(status, &rwflags_cp, &rwflags_pc))
+        {
+            goto bad;
+        }
+    }
+    proxy_connection_io_requeue(pc, rwflags_pc, es);
+    proxy_connection_io_requeue(cp, rwflags_cp, es);
+
+    return true;
+
+bad:
+    proxy_entry_mark_for_close(pc, es);
+    return false;
+}
+
+/*
+ * This is the main function for the port share proxy background process.
+ */
+static void
+port_share_proxy(const struct sockaddr_in hostaddr,
+                 const socket_descriptor_t sd_control,
+                 const int max_initial_buf,
+                 const char *journal_dir)
+{
+    if (send_control(sd_control, RESPONSE_INIT_SUCCEEDED) >= 0)
+    {
+        void *sd_control_marker = (void *)1;
+        int maxevents = 256;
+        struct event_set *es;
+        struct event_set_return esr[64];
+        struct proxy_connection *list = NULL;
+        time_t last_housekeeping = 0;
+
+        msg(D_PS_PROXY, "PORT SHARE PROXY: proxy starting");
+
+        es = event_set_init(&maxevents, 0);
+        event_ctl(es, sd_control, EVENT_READ, sd_control_marker);
+        while (true)
+        {
+            int n_events;
+            struct timeval tv;
+            time_t current;
+
+            tv.tv_sec = 10;
+            tv.tv_usec = 0;
+            n_events = event_wait(es, &tv, esr, SIZE(esr));
+            /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait returned %d", n_events);*/
+            current = time(NULL);
+            if (n_events > 0)
+            {
+                int i;
+                for (i = 0; i < n_events; ++i)
+                {
+                    const struct event_set_return *e = &esr[i];
+                    if (e->arg == sd_control_marker)
+                    {
+                        if (!control_message_from_parent(sd_control, &list, es, hostaddr, max_initial_buf, journal_dir))
+                        {
+                            goto done;
+                        }
+                    }
+                    else
+                    {
+                        struct proxy_connection *pc = (struct proxy_connection *)e->arg;
+                        if (pc->defined)
+                        {
+                            proxy_connection_io_dispatch(pc, e->rwflags, es);
+                        }
+                    }
+                }
+            }
+            else if (n_events < 0)
+            {
+                dmsg(D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait failed");
+            }
+            if (current > last_housekeeping)
+            {
+                proxy_list_housekeeping(&list);
+                last_housekeeping = current;
+            }
+        }
+
+done:
+        proxy_list_close(&list);
+        event_free(es);
+    }
+    msg(M_INFO, "PORT SHARE PROXY: proxy exiting");
+}
+
+/*
+ * Called from the main OpenVPN process to enable the port
+ * share proxy.
+ */
+struct port_share *
+port_share_open(const char *host,
+                const char *port,
+                const int max_initial_buf,
+                const char *journal_dir)
+{
+    pid_t pid;
+    socket_descriptor_t fd[2];
+    struct sockaddr_in hostaddr;
+    struct port_share *ps;
+    int status;
+    struct addrinfo *ai;
+
+    ALLOC_OBJ_CLEAR(ps, struct port_share);
+    ps->foreground_fd = -1;
+    ps->background_pid = -1;
+
+    /*
+     * Get host's IP address
+     */
+
+    status = openvpn_getaddrinfo(GETADDR_RESOLVE|GETADDR_FATAL,
+                                 host, port,  0, NULL, AF_INET, &ai);
+    ASSERT(status==0);
+    hostaddr = *((struct sockaddr_in *) ai->ai_addr);
+    freeaddrinfo(ai);
+
+    /*
+     * Make a socket for foreground and background processes
+     * to communicate.
+     */
+    if (socketpair(PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
+    {
+        msg(M_WARN, "PORT SHARE: socketpair call failed");
+        goto error;
+    }
+
+    /*
+     * Fork off background proxy process.
+     */
+    pid = fork();
+
+    if (pid)
+    {
+        int status;
+
+        /*
+         * Foreground Process
+         */
+
+        ps->background_pid = pid;
+
+        /* close our copy of child's socket */
+        openvpn_close_socket(fd[1]);
+
+        /* don't let future subprocesses inherit child socket */
+        set_cloexec(fd[0]);
+
+        /* wait for background child process to initialize */
+        status = recv_control(fd[0]);
+        if (status == RESPONSE_INIT_SUCCEEDED)
+        {
+            /* note that this will cause possible EAGAIN when writing to
+             * control socket if proxy process is backlogged */
+            set_nonblock(fd[0]);
+
+            ps->foreground_fd = fd[0];
+            return ps;
+        }
+        else
+        {
+            msg(M_ERR, "PORT SHARE: unexpected init recv_control status=%d", status);
+        }
+    }
+    else
+    {
+        /*
+         * Background Process
+         */
+
+        /* Ignore most signals (the parent will receive them) */
+        set_signals();
+
+        /* Let msg know that we forked */
+        msg_forked();
+
+#ifdef ENABLE_MANAGEMENT
+        /* Don't interact with management interface */
+        management = NULL;
+#endif
+
+        /* close all parent fds except our socket back to parent */
+        close_fds_except(fd[1]);
+
+        /* no blocking on control channel back to parent */
+        set_nonblock(fd[1]);
+
+        /* initialize prng */
+        prng_init(NULL, 0);
+
+        /* execute the event loop */
+        port_share_proxy(hostaddr, fd[1], max_initial_buf, journal_dir);
+
+        openvpn_close_socket(fd[1]);
+
+        exit(0);
+        return NULL; /* NOTREACHED */
+    }
+
+error:
+    port_share_close(ps);
+    return NULL;
+}
+
+void
+port_share_close(struct port_share *ps)
+{
+    if (ps)
+    {
+        if (ps->foreground_fd >= 0)
+        {
+            /* tell background process to exit */
+            port_share_sendmsg(ps->foreground_fd, COMMAND_EXIT, NULL, SOCKET_UNDEFINED);
+
+            /* wait for background process to exit */
+            dmsg(D_PS_PROXY_DEBUG, "PORT SHARE: waiting for background process to exit");
+            if (ps->background_pid > 0)
+            {
+                waitpid(ps->background_pid, NULL, 0);
+            }
+            dmsg(D_PS_PROXY_DEBUG, "PORT SHARE: background process exited");
+
+            openvpn_close_socket(ps->foreground_fd);
+            ps->foreground_fd = -1;
+        }
+
+        free(ps);
+    }
+}
+
+void
+port_share_abort(struct port_share *ps)
+{
+    if (ps)
+    {
+        /* tell background process to exit */
+        if (ps->foreground_fd >= 0)
+        {
+            send_control(ps->foreground_fd, COMMAND_EXIT);
+            openvpn_close_socket(ps->foreground_fd);
+            ps->foreground_fd = -1;
+        }
+    }
+}
+
+/*
+ * Given either the first 2 or 3 bytes of an initial client -> server
+ * data payload, return true if the protocol is that of an OpenVPN
+ * client attempting to connect with an OpenVPN server.
+ */
+bool
+is_openvpn_protocol(const struct buffer *buf)
+{
+    const unsigned char *p = (const unsigned char *) BSTR(buf);
+    const int len = BLEN(buf);
+    if (len >= 3)
+    {
+        return p[0] == 0
+               && p[1] >= 14
+               && p[2] == (P_CONTROL_HARD_RESET_CLIENT_V2<<P_OPCODE_SHIFT);
+    }
+    else if (len >= 2)
+    {
+        return p[0] == 0 && p[1] >= 14;
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Called from the foreground process.  Send a message to the background process that it
+ * should proxy the TCP client on sd to the host/port defined in the initial port_share_open
+ * call.
+ */
+void
+port_share_redirect(struct port_share *ps, const struct buffer *head, socket_descriptor_t sd)
+{
+    if (ps)
+    {
+        port_share_sendmsg(ps->foreground_fd, COMMAND_REDIRECT, head, sd);
+    }
+}
+
+#endif /* if PORT_SHARE */
diff --git a/src/openvpn/ps.h b/src/openvpn/ps.h
new file mode 100644
index 0000000..b4490f5
--- /dev/null
+++ b/src/openvpn/ps.h
@@ -0,0 +1,59 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PS_H
+#define PS_H
+
+#if PORT_SHARE
+
+#include "basic.h"
+#include "buffer.h"
+#include "ssl.h"
+
+typedef void (*post_fork_cleanup_func_t)(void *arg);
+
+struct port_share {
+    /* Foreground's socket to background process */
+    socket_descriptor_t foreground_fd;
+
+    /* Process ID of background process */
+    pid_t background_pid;
+};
+
+extern struct port_share *port_share;
+
+struct port_share *port_share_open(const char *host,
+                                   const char *port,
+                                   const int max_initial_buf,
+                                   const char *journal_dir);
+
+void port_share_close(struct port_share *ps);
+
+void port_share_abort(struct port_share *ps);
+
+bool is_openvpn_protocol(const struct buffer *buf);
+
+void port_share_redirect(struct port_share *ps, const struct buffer *head, socket_descriptor_t sd);
+
+#endif /* if PORT_SHARE */
+#endif /* ifndef PS_H */
diff --git a/src/openvpn/push.c b/src/openvpn/push.c
new file mode 100644
index 0000000..002be23
--- /dev/null
+++ b/src/openvpn/push.c
@@ -0,0 +1,855 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "push.h"
+#include "options.h"
+#include "ssl.h"
+#include "ssl_verify.h"
+#include "manage.h"
+
+#include "memdbg.h"
+
+#if P2MP
+
+static char push_reply_cmd[] = "PUSH_REPLY";
+
+/*
+ * Auth username/password
+ *
+ * Client received an authentication failed message from server.
+ * Runs on client.
+ */
+void
+receive_auth_failed(struct context *c, const struct buffer *buffer)
+{
+    msg(M_VERB0, "AUTH: Received control message: %s", BSTR(buffer));
+    c->options.no_advance = true;
+
+    if (c->options.pull)
+    {
+        /* Before checking how to react on AUTH_FAILED, first check if the
+         * failed auth might be the result of an expired auth-token.
+         * Note that a server restart will trigger a generic AUTH_FAILED
+         * instead an AUTH_FAILED,SESSION so handle all AUTH_FAILED message
+         * identical for this scenario */
+        if (ssl_clean_auth_token())
+        {
+            c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Auth failure error */
+            c->sig->signal_text = "auth-failure (auth-token)";
+        }
+        else
+        {
+            switch (auth_retry_get())
+            {
+            case AR_NONE:
+                c->sig->signal_received = SIGTERM; /* SOFT-SIGTERM -- Auth failure error */
+                break;
+
+            case AR_INTERACT:
+                ssl_purge_auth(false);
+
+            case AR_NOINTERACT:
+                c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- Auth failure error */
+                break;
+
+            default:
+                ASSERT(0);
+            }
+            c->sig->signal_text = "auth-failure";
+        }
+#ifdef ENABLE_MANAGEMENT
+        if (management)
+        {
+            const char *reason = NULL;
+            struct buffer buf = *buffer;
+            if (buf_string_compare_advance(&buf, "AUTH_FAILED,") && BLEN(&buf))
+            {
+                reason = BSTR(&buf);
+            }
+            management_auth_failure(management, UP_TYPE_AUTH, reason);
+        }
+#endif
+        /*
+         * Save the dynamic-challenge text even when management is defined
+         */
+        {
+#ifdef ENABLE_CLIENT_CR
+            struct buffer buf = *buffer;
+            if (buf_string_match_head_str(&buf, "AUTH_FAILED,CRV1:") && BLEN(&buf))
+            {
+                buf_advance(&buf, 12); /* Length of "AUTH_FAILED," substring */
+                ssl_put_auth_challenge(BSTR(&buf));
+            }
+#endif
+        }
+    }
+}
+
+/*
+ * Act on received restart message from server
+ */
+void
+server_pushed_signal(struct context *c, const struct buffer *buffer, const bool restart, const int adv)
+{
+    if (c->options.pull)
+    {
+        struct buffer buf = *buffer;
+        const char *m = "";
+        if (buf_advance(&buf, adv) && buf_read_u8(&buf) == ',' && BLEN(&buf))
+        {
+            m = BSTR(&buf);
+        }
+
+        /* preserve cached passwords? */
+        /* advance to next server? */
+        {
+            bool purge = true;
+
+            if (m[0] == '[')
+            {
+                int i;
+                for (i = 1; m[i] != '\0' && m[i] != ']'; ++i)
+                {
+                    if (m[i] == 'P')
+                    {
+                        purge = false;
+                    }
+                    else if (m[i] == 'N')
+                    {
+                        /* next server? */
+                        c->options.no_advance = false;
+                    }
+                }
+            }
+            if (purge)
+            {
+                ssl_purge_auth(true);
+            }
+        }
+
+        if (restart)
+        {
+            msg(D_STREAM_ERRORS, "Connection reset command was pushed by server ('%s')", m);
+            c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- server-pushed connection reset */
+            c->sig->signal_text = "server-pushed-connection-reset";
+        }
+        else
+        {
+            msg(D_STREAM_ERRORS, "Halt command was pushed by server ('%s')", m);
+            c->sig->signal_received = SIGTERM; /* SOFT-SIGTERM -- server-pushed halt */
+            c->sig->signal_text = "server-pushed-halt";
+        }
+#ifdef ENABLE_MANAGEMENT
+        if (management)
+        {
+            management_notify(management, "info", c->sig->signal_text, m);
+        }
+#endif
+    }
+}
+
+#if P2MP_SERVER
+/**
+ * Add an option to the given push list by providing a format string.
+ *
+ * The string added to the push options is allocated in o->gc, so the caller
+ * does not have to preserve anything.
+ *
+ * @param gc        GC arena where options are allocated
+ * @param push_list Push list containing options
+ * @param msglevel  The message level to use when printing errors
+ * @param fmt       Format string for the option
+ * @param ...       Format string arguments
+ *
+ * @return true on success, false on failure.
+ */
+static bool push_option_fmt(struct gc_arena *gc, struct push_list *push_list,
+                            int msglevel, const char *fmt, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 4, 5)))
+#else
+__attribute__ ((format(__printf__, 4, 5)))
+#endif
+#endif
+;
+
+/*
+ * Send auth failed message from server to client.
+ */
+void
+send_auth_failed(struct context *c, const char *client_reason)
+{
+    struct gc_arena gc = gc_new();
+    static const char auth_failed[] = "AUTH_FAILED";
+    size_t len;
+
+    schedule_exit(c, c->options.scheduled_exit_interval, SIGTERM);
+
+    len = (client_reason ? strlen(client_reason)+1 : 0) + sizeof(auth_failed);
+    if (len > PUSH_BUNDLE_SIZE)
+    {
+        len = PUSH_BUNDLE_SIZE;
+    }
+
+    {
+        struct buffer buf = alloc_buf_gc(len, &gc);
+        buf_printf(&buf, auth_failed);
+        if (client_reason)
+        {
+            buf_printf(&buf, ",%s", client_reason);
+        }
+        send_control_channel_string(c, BSTR(&buf), D_PUSH);
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Send restart message from server to client.
+ */
+void
+send_restart(struct context *c, const char *kill_msg)
+{
+    schedule_exit(c, c->options.scheduled_exit_interval, SIGTERM);
+    send_control_channel_string(c, kill_msg ? kill_msg : "RESTART", D_PUSH);
+}
+
+#endif /* if P2MP_SERVER */
+
+/*
+ * Push/Pull
+ */
+
+void
+incoming_push_message(struct context *c, const struct buffer *buffer)
+{
+    struct gc_arena gc = gc_new();
+    unsigned int option_types_found = 0;
+    int status;
+
+    msg(D_PUSH, "PUSH: Received control message: '%s'", sanitize_control_message(BSTR(buffer), &gc));
+
+    status = process_incoming_push_msg(c,
+                                       buffer,
+                                       c->options.pull,
+                                       pull_permission_mask(c),
+                                       &option_types_found);
+
+    if (status == PUSH_MSG_ERROR)
+    {
+        msg(D_PUSH_ERRORS, "WARNING: Received bad push/pull message: %s", sanitize_control_message(BSTR(buffer), &gc));
+    }
+    else if (status == PUSH_MSG_REPLY || status == PUSH_MSG_CONTINUATION)
+    {
+        c->options.push_option_types_found |= option_types_found;
+
+        /* delay bringing tun/tap up until --push parms received from remote */
+        if (status == PUSH_MSG_REPLY)
+        {
+            if (!do_up(c, true, c->options.push_option_types_found))
+            {
+                msg(D_PUSH_ERRORS, "Failed to open tun/tap interface");
+                goto error;
+            }
+        }
+        event_timeout_clear(&c->c2.push_request_interval);
+    }
+    else if (status == PUSH_MSG_REQUEST)
+    {
+        if (c->options.mode == MODE_SERVER)
+        {
+            struct frame *frame_fragment = NULL;
+#ifdef ENABLE_FRAGMENT
+            if (c->options.ce.fragment)
+            {
+                frame_fragment = &c->c2.frame_fragment;
+            }
+#endif
+            struct tls_session *session = &c->c2.tls_multi->session[TM_ACTIVE];
+            if (!tls_session_update_crypto_params(session, &c->options,
+                                                  &c->c2.frame, frame_fragment))
+            {
+                msg(D_TLS_ERRORS, "TLS Error: initializing data channel failed");
+                goto error;
+            }
+        }
+    }
+
+    goto cleanup;
+error:
+    register_signal(c, SIGUSR1, "process-push-msg-failed");
+cleanup:
+    gc_free(&gc);
+}
+
+bool
+send_push_request(struct context *c)
+{
+    const int max_push_requests = c->options.handshake_window / PUSH_REQUEST_INTERVAL;
+    if (++c->c2.n_sent_push_requests <= max_push_requests)
+    {
+        return send_control_channel_string(c, "PUSH_REQUEST", D_PUSH);
+    }
+    else
+    {
+        msg(D_STREAM_ERRORS, "No reply from server after sending %d push requests", max_push_requests);
+        c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- server-pushed connection reset */
+        c->sig->signal_text = "no-push-reply";
+        return false;
+    }
+}
+
+#if P2MP_SERVER
+
+/**
+ * Prepare push options, based on local options and available peer info.
+ *
+ * @param context       context structure storing data for VPN tunnel
+ * @param gc            gc arena for allocating push options
+ * @param push_list     push list to where options are added
+ *
+ * @return true on success, false on failure.
+ */
+static bool
+prepare_push_reply(struct context *c, struct gc_arena *gc,
+                   struct push_list *push_list)
+{
+    const char *optstr = NULL;
+    struct tls_multi *tls_multi = c->c2.tls_multi;
+    const char *const peer_info = tls_multi->peer_info;
+    struct options *o = &c->options;
+
+    /* ipv6 */
+    if (c->c2.push_ifconfig_ipv6_defined && !o->push_ifconfig_ipv6_blocked)
+    {
+        push_option_fmt(gc, push_list, M_USAGE, "ifconfig-ipv6 %s/%d %s",
+                        print_in6_addr(c->c2.push_ifconfig_ipv6_local, 0, gc),
+                        c->c2.push_ifconfig_ipv6_netbits,
+                        print_in6_addr(c->c2.push_ifconfig_ipv6_remote,
+                                       0, gc));
+    }
+
+    /* ipv4 */
+    if (c->c2.push_ifconfig_defined && c->c2.push_ifconfig_local
+        && c->c2.push_ifconfig_remote_netmask)
+    {
+        in_addr_t ifconfig_local = c->c2.push_ifconfig_local;
+        if (c->c2.push_ifconfig_local_alias)
+        {
+            ifconfig_local = c->c2.push_ifconfig_local_alias;
+        }
+        push_option_fmt(gc, push_list, M_USAGE, "ifconfig %s %s",
+                        print_in_addr_t(ifconfig_local, 0, gc),
+                        print_in_addr_t(c->c2.push_ifconfig_remote_netmask,
+                                        0, gc));
+    }
+
+    /* Send peer-id if client supports it */
+    optstr = peer_info ? strstr(peer_info, "IV_PROTO=") : NULL;
+    if (optstr)
+    {
+        int proto = 0;
+        int r = sscanf(optstr, "IV_PROTO=%d", &proto);
+        if ((r == 1) && (proto >= 2))
+        {
+            push_option_fmt(gc, push_list, M_USAGE, "peer-id %d",
+                            tls_multi->peer_id);
+            tls_multi->use_peer_id = true;
+        }
+    }
+
+    /* Push cipher if client supports Negotiable Crypto Parameters */
+    if (tls_peer_info_ncp_ver(peer_info) >= 2 && o->ncp_enabled)
+    {
+        /* if we have already created our key, we cannot *change* our own
+         * cipher -> so log the fact and push the "what we have now" cipher
+         * (so the client is always told what we expect it to use)
+         */
+        const struct tls_session *session = &tls_multi->session[TM_ACTIVE];
+        if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
+        {
+            msg( M_INFO, "PUSH: client wants to negotiate cipher (NCP), but "
+                 "server has already generated data channel keys, "
+                 "re-sending previously negotiated cipher '%s'",
+                 o->ciphername );
+        }
+        else
+        {
+            /* Push the first cipher from --ncp-ciphers to the client.
+             * TODO: actual negotiation, instead of server dictatorship. */
+            char *push_cipher = string_alloc(o->ncp_ciphers, &o->gc);
+            o->ciphername = strtok(push_cipher, ":");
+        }
+        push_option_fmt(gc, push_list, M_USAGE, "cipher %s", o->ciphername);
+    }
+    else if (o->ncp_enabled)
+    {
+        tls_poor_mans_ncp(o, tls_multi->remote_ciphername);
+    }
+
+    /* If server uses --auth-gen-token and we have an auth token
+     * to send to the client
+     */
+    if (false == tls_multi->auth_token_sent && NULL != tls_multi->auth_token)
+    {
+        push_option_fmt(gc, push_list, M_USAGE,
+                        "auth-token %s", tls_multi->auth_token);
+        tls_multi->auth_token_sent = true;
+    }
+    return true;
+}
+
+static bool
+send_push_options(struct context *c, struct buffer *buf,
+                  struct push_list *push_list, int safe_cap,
+                  bool *push_sent, bool *multi_push)
+{
+    struct push_entry *e = push_list->head;
+
+    while (e)
+    {
+        if (e->enable)
+        {
+            const int l = strlen(e->option);
+            if (BLEN(buf) + l >= safe_cap)
+            {
+                buf_printf(buf, ",push-continuation 2");
+                {
+                    const bool status = send_control_channel_string(c, BSTR(buf), D_PUSH);
+                    if (!status)
+                    {
+                        return false;
+                    }
+                    *push_sent = true;
+                    *multi_push = true;
+                    buf_reset_len(buf);
+                    buf_printf(buf, "%s", push_reply_cmd);
+                }
+            }
+            if (BLEN(buf) + l >= safe_cap)
+            {
+                msg(M_WARN, "--push option is too long");
+                return false;
+            }
+            buf_printf(buf, ",%s", e->option);
+        }
+        e = e->next;
+    }
+    return true;
+}
+
+static bool
+send_push_reply(struct context *c, struct push_list *per_client_push_list)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer buf = alloc_buf_gc(PUSH_BUNDLE_SIZE, &gc);
+    bool multi_push = false;
+    const int extra = 84; /* extra space for possible trailing ifconfig and push-continuation */
+    const int safe_cap = BCAP(&buf) - extra;
+    bool push_sent = false;
+
+    buf_printf(&buf, "%s", push_reply_cmd);
+
+    /* send options which are common to all clients */
+    if (!send_push_options(c, &buf, &c->options.push_list, safe_cap,
+                           &push_sent, &multi_push))
+    {
+        goto fail;
+    }
+
+    /* send client-specific options */
+    if (!send_push_options(c, &buf, per_client_push_list, safe_cap,
+                           &push_sent, &multi_push))
+    {
+        goto fail;
+    }
+
+    if (multi_push)
+    {
+        buf_printf(&buf, ",push-continuation 1");
+    }
+
+    if (BLEN(&buf) > sizeof(push_reply_cmd)-1)
+    {
+        const bool status = send_control_channel_string(c, BSTR(&buf), D_PUSH);
+        if (!status)
+        {
+            goto fail;
+        }
+        push_sent = true;
+    }
+
+    /* If nothing have been pushed, send an empty push,
+     * as the client is expecting a response
+     */
+    if (!push_sent)
+    {
+        bool status = false;
+
+        buf_reset_len(&buf);
+        buf_printf(&buf, "%s", push_reply_cmd);
+        status = send_control_channel_string(c, BSTR(&buf), D_PUSH);
+        if (!status)
+        {
+            goto fail;
+        }
+    }
+
+    gc_free(&gc);
+    return true;
+
+fail:
+    gc_free(&gc);
+    return false;
+}
+
+static void
+push_option_ex(struct gc_arena *gc, struct push_list *push_list,
+               const char *opt, bool enable, int msglevel)
+{
+    if (!string_class(opt, CC_ANY, CC_COMMA))
+    {
+        msg(msglevel, "PUSH OPTION FAILED (illegal comma (',') in string): '%s'", opt);
+    }
+    else
+    {
+        struct push_entry *e;
+        ALLOC_OBJ_CLEAR_GC(e, struct push_entry, gc);
+        e->enable = true;
+        e->option = opt;
+        if (push_list->head)
+        {
+            ASSERT(push_list->tail);
+            push_list->tail->next = e;
+            push_list->tail = e;
+        }
+        else
+        {
+            ASSERT(!push_list->tail);
+            push_list->head = e;
+            push_list->tail = e;
+        }
+    }
+}
+
+void
+push_option(struct options *o, const char *opt, int msglevel)
+{
+    push_option_ex(&o->gc, &o->push_list, opt, true, msglevel);
+}
+
+void
+clone_push_list(struct options *o)
+{
+    if (o->push_list.head)
+    {
+        const struct push_entry *e = o->push_list.head;
+        push_reset(o);
+        while (e)
+        {
+            push_option_ex(&o->gc, &o->push_list,
+                           string_alloc(e->option, &o->gc), true, M_FATAL);
+            e = e->next;
+        }
+    }
+}
+
+void
+push_options(struct options *o, char **p, int msglevel, struct gc_arena *gc)
+{
+    const char **argv = make_extended_arg_array(p, gc);
+    char *opt = print_argv(argv, gc, 0);
+    push_option(o, opt, msglevel);
+}
+
+static bool
+push_option_fmt(struct gc_arena *gc, struct push_list *push_list,
+                int msglevel, const char *format, ...)
+{
+    va_list arglist;
+    char tmp[256] = {0};
+    int len;
+    va_start(arglist, format);
+    len = vsnprintf(tmp, sizeof(tmp), format, arglist);
+    va_end(arglist);
+    if (len > sizeof(tmp)-1)
+    {
+        return false;
+    }
+    push_option_ex(gc, push_list, string_alloc(tmp, gc), true, msglevel);
+    return true;
+}
+
+void
+push_reset(struct options *o)
+{
+    CLEAR(o->push_list);
+}
+
+void
+push_remove_option(struct options *o, const char *p)
+{
+    msg(D_PUSH_DEBUG, "PUSH_REMOVE searching for: '%s'", p);
+
+    /* ifconfig-ipv6 is special, as not part of the push list */
+    if (streq( p, "ifconfig-ipv6" ))
+    {
+        o->push_ifconfig_ipv6_blocked = true;
+        return;
+    }
+
+    if (o && o->push_list.head)
+    {
+        struct push_entry *e = o->push_list.head;
+
+        /* cycle through the push list */
+        while (e)
+        {
+            if (e->enable
+                && strncmp( e->option, p, strlen(p) ) == 0)
+            {
+                msg(D_PUSH_DEBUG, "PUSH_REMOVE removing: '%s'", e->option);
+                e->enable = false;
+            }
+
+            e = e->next;
+        }
+    }
+}
+#endif /* if P2MP_SERVER */
+
+#if P2MP_SERVER
+int
+process_incoming_push_request(struct context *c)
+{
+    int ret = PUSH_MSG_ERROR;
+
+#ifdef ENABLE_ASYNC_PUSH
+    c->c2.push_request_received = true;
+#endif
+    if (tls_authentication_status(c->c2.tls_multi, 0) == TLS_AUTHENTICATION_FAILED || c->c2.context_auth == CAS_FAILED)
+    {
+        const char *client_reason = tls_client_reason(c->c2.tls_multi);
+        send_auth_failed(c, client_reason);
+        ret = PUSH_MSG_AUTH_FAILURE;
+    }
+    else if (!c->c2.push_reply_deferred && c->c2.context_auth == CAS_SUCCEEDED)
+    {
+        time_t now;
+
+        openvpn_time(&now);
+        if (c->c2.sent_push_reply_expiry > now)
+        {
+            ret = PUSH_MSG_ALREADY_REPLIED;
+        }
+        else
+        {
+            /* per-client push options - peer-id, cipher, ifconfig, ipv6-ifconfig */
+            struct push_list push_list;
+            struct gc_arena gc = gc_new();
+
+            CLEAR(push_list);
+            if (prepare_push_reply(c, &gc, &push_list)
+                && send_push_reply(c, &push_list))
+            {
+                ret = PUSH_MSG_REQUEST;
+                c->c2.sent_push_reply_expiry = now + 30;
+            }
+            gc_free(&gc);
+        }
+    }
+    else
+    {
+        ret = PUSH_MSG_REQUEST_DEFERRED;
+    }
+
+    return ret;
+}
+#endif /* if P2MP_SERVER */
+
+static void
+push_update_digest(md_ctx_t *ctx, struct buffer *buf, const struct options *opt)
+{
+    char line[OPTION_PARM_SIZE];
+    while (buf_parse(buf, ',', line, sizeof(line)))
+    {
+        /* peer-id might change on restart and this should not trigger reopening tun */
+        if (strprefix(line, "peer-id "))
+        {
+            continue;
+        }
+        /* tun reopen only needed if cipher change can change tun MTU */
+        if (strprefix(line, "cipher ") && !opt->ce.tun_mtu_defined)
+        {
+            continue;
+        }
+        md_ctx_update(ctx, (const uint8_t *) line, strlen(line)+1);
+    }
+}
+
+int
+process_incoming_push_msg(struct context *c,
+                          const struct buffer *buffer,
+                          bool honor_received_options,
+                          unsigned int permission_mask,
+                          unsigned int *option_types_found)
+{
+    int ret = PUSH_MSG_ERROR;
+    struct buffer buf = *buffer;
+
+#if P2MP_SERVER
+    if (buf_string_compare_advance(&buf, "PUSH_REQUEST"))
+    {
+        ret = process_incoming_push_request(c);
+    }
+    else
+#endif
+
+    if (honor_received_options && buf_string_compare_advance(&buf, "PUSH_REPLY"))
+    {
+        const uint8_t ch = buf_read_u8(&buf);
+        if (ch == ',')
+        {
+            struct buffer buf_orig = buf;
+            if (!c->c2.pulled_options_digest_init_done)
+            {
+                c->c2.pulled_options_state = md_ctx_new();
+                md_ctx_init(c->c2.pulled_options_state, md_kt_get("SHA256"));
+                c->c2.pulled_options_digest_init_done = true;
+            }
+            if (!c->c2.did_pre_pull_restore)
+            {
+                pre_pull_restore(&c->options, &c->c2.gc);
+                c->c2.did_pre_pull_restore = true;
+            }
+            if (apply_push_options(&c->options,
+                                   &buf,
+                                   permission_mask,
+                                   option_types_found,
+                                   c->c2.es))
+            {
+                push_update_digest(c->c2.pulled_options_state, &buf_orig,
+                                   &c->options);
+                switch (c->options.push_continuation)
+                {
+                    case 0:
+                    case 1:
+                        md_ctx_final(c->c2.pulled_options_state, c->c2.pulled_options_digest.digest);
+                        md_ctx_cleanup(c->c2.pulled_options_state);
+                        md_ctx_free(c->c2.pulled_options_state);
+                        c->c2.pulled_options_state = NULL;
+                        c->c2.pulled_options_digest_init_done = false;
+                        ret = PUSH_MSG_REPLY;
+                        break;
+
+                    case 2:
+                        ret = PUSH_MSG_CONTINUATION;
+                        break;
+                }
+            }
+        }
+        else if (ch == '\0')
+        {
+            ret = PUSH_MSG_REPLY;
+        }
+        /* show_settings (&c->options); */
+    }
+    return ret;
+}
+
+#if P2MP_SERVER
+
+/*
+ * Remove iroutes from the push_list.
+ */
+void
+remove_iroutes_from_push_route_list(struct options *o)
+{
+    if (o && o->push_list.head && o->iroutes)
+    {
+        struct gc_arena gc = gc_new();
+        struct push_entry *e = o->push_list.head;
+
+        /* cycle through the push list */
+        while (e)
+        {
+            char *p[MAX_PARMS];
+            bool enable = true;
+
+            /* parse the push item */
+            CLEAR(p);
+            if (e->enable
+                && parse_line(e->option, p, SIZE(p), "[PUSH_ROUTE_REMOVE]", 1, D_ROUTE_DEBUG, &gc))
+            {
+                /* is the push item a route directive? */
+                if (p[0] && !strcmp(p[0], "route") && !p[3])
+                {
+                    /* get route parameters */
+                    bool status1, status2;
+                    const in_addr_t network = getaddr(GETADDR_HOST_ORDER, p[1], 0, &status1, NULL);
+                    const in_addr_t netmask = getaddr(GETADDR_HOST_ORDER, p[2] ? p[2] : "255.255.255.255", 0, &status2, NULL);
+
+                    /* did route parameters parse correctly? */
+                    if (status1 && status2)
+                    {
+                        const struct iroute *ir;
+
+                        /* does route match an iroute? */
+                        for (ir = o->iroutes; ir != NULL; ir = ir->next)
+                        {
+                            if (network == ir->network && netmask == netbits_to_netmask(ir->netbits >= 0 ? ir->netbits : 32))
+                            {
+                                enable = false;
+                                break;
+                            }
+                        }
+                    }
+                }
+
+                /* should we copy the push item? */
+                e->enable = enable;
+                if (!enable)
+                {
+                    msg(D_PUSH, "REMOVE PUSH ROUTE: '%s'", e->option);
+                }
+            }
+
+            e = e->next;
+        }
+
+        gc_free(&gc);
+    }
+}
+
+#endif /* if P2MP_SERVER */
+
+#endif /* if P2MP */
diff --git a/src/openvpn/push.h b/src/openvpn/push.h
new file mode 100644
index 0000000..5f6181e
--- /dev/null
+++ b/src/openvpn/push.h
@@ -0,0 +1,74 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef PUSH_H
+#define PUSH_H
+
+#if P2MP
+
+#include "forward.h"
+
+#define PUSH_MSG_ERROR            0
+#define PUSH_MSG_REQUEST          1
+#define PUSH_MSG_REPLY            2
+#define PUSH_MSG_REQUEST_DEFERRED 3
+#define PUSH_MSG_AUTH_FAILURE     4
+#define PUSH_MSG_CONTINUATION     5
+#define PUSH_MSG_ALREADY_REPLIED  6
+
+int process_incoming_push_request(struct context *c);
+
+int process_incoming_push_msg(struct context *c,
+                              const struct buffer *buffer,
+                              bool honor_received_options,
+                              unsigned int permission_mask,
+                              unsigned int *option_types_found);
+
+bool send_push_request(struct context *c);
+
+void receive_auth_failed(struct context *c, const struct buffer *buffer);
+
+void server_pushed_signal(struct context *c, const struct buffer *buffer, const bool restart, const int adv);
+
+void incoming_push_message(struct context *c, const struct buffer *buffer);
+
+#if P2MP_SERVER
+void clone_push_list(struct options *o);
+
+void push_option(struct options *o, const char *opt, int msglevel);
+
+void push_options(struct options *o, char **p, int msglevel, struct gc_arena *gc);
+
+void push_reset(struct options *o);
+
+void push_remove_option(struct options *o, const char *p);
+
+void remove_iroutes_from_push_route_list(struct options *o);
+
+void send_auth_failed(struct context *c, const char *client_reason);
+
+void send_restart(struct context *c, const char *kill_msg);
+
+#endif
+#endif /* if P2MP */
+#endif /* ifndef PUSH_H */
diff --git a/src/openvpn/pushlist.h b/src/openvpn/pushlist.h
new file mode 100644
index 0000000..23b0ee5
--- /dev/null
+++ b/src/openvpn/pushlist.h
@@ -0,0 +1,41 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#if !defined(PUSHLIST_H) && P2MP && P2MP_SERVER
+#define PUSHLIST_H
+
+/* parameters to be pushed to peer */
+
+struct push_entry {
+    struct push_entry *next;
+    bool enable;
+    const char *option;
+};
+
+struct push_list {
+    struct push_entry *head;
+    struct push_entry *tail;
+};
+
+
+#endif
diff --git a/src/openvpn/reliable.c b/src/openvpn/reliable.c
new file mode 100644
index 0000000..8f5e173
--- /dev/null
+++ b/src/openvpn/reliable.c
@@ -0,0 +1,811 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * These routines implement a reliability layer on top of UDP,
+ * so that SSL/TLS can be run over UDP.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "buffer.h"
+#include "error.h"
+#include "common.h"
+#include "reliable.h"
+
+#include "memdbg.h"
+
+/*
+ * verify that test - base < extent while allowing for base or test wraparound
+ */
+static inline bool
+reliable_pid_in_range1(const packet_id_type test,
+                       const packet_id_type base,
+                       const unsigned int extent)
+{
+    if (test >= base)
+    {
+        if (test - base < extent)
+        {
+            return true;
+        }
+    }
+    else
+    {
+        if ((test+0x80000000u) - (base+0x80000000u) < extent)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/*
+ * verify that test < base + extent while allowing for base or test wraparound
+ */
+static inline bool
+reliable_pid_in_range2(const packet_id_type test,
+                       const packet_id_type base,
+                       const unsigned int extent)
+{
+    if (base + extent >= base)
+    {
+        if (test < base + extent)
+        {
+            return true;
+        }
+    }
+    else
+    {
+        if ((test+0x80000000u) < (base+0x80000000u) + extent)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/*
+ * verify that p1 < p2  while allowing for p1 or p2 wraparound
+ */
+static inline bool
+reliable_pid_min(const packet_id_type p1,
+                 const packet_id_type p2)
+{
+    return !reliable_pid_in_range1(p1, p2, 0x80000000u);
+}
+
+/* check if a particular packet_id is present in ack */
+static inline bool
+reliable_ack_packet_id_present(struct reliable_ack *ack, packet_id_type pid)
+{
+    int i;
+    for (i = 0; i < ack->len; ++i)
+    {
+        if (ack->packet_id[i] == pid)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+/* get a packet_id from buf */
+bool
+reliable_ack_read_packet_id(struct buffer *buf, packet_id_type *pid)
+{
+    packet_id_type net_pid;
+
+    if (buf_read(buf, &net_pid, sizeof(net_pid)))
+    {
+        *pid = ntohpid(net_pid);
+        dmsg(D_REL_DEBUG, "ACK read ID " packet_id_format " (buf->len=%d)",
+             (packet_id_print_type)*pid, buf->len);
+        return true;
+    }
+
+    dmsg(D_REL_LOW, "ACK read ID FAILED (buf->len=%d)", buf->len);
+    return false;
+}
+
+/* acknowledge a packet_id by adding it to a struct reliable_ack */
+bool
+reliable_ack_acknowledge_packet_id(struct reliable_ack *ack, packet_id_type pid)
+{
+    if (!reliable_ack_packet_id_present(ack, pid) && ack->len < RELIABLE_ACK_SIZE)
+    {
+        ack->packet_id[ack->len++] = pid;
+        dmsg(D_REL_DEBUG, "ACK acknowledge ID " packet_id_format " (ack->len=%d)",
+             (packet_id_print_type)pid, ack->len);
+        return true;
+    }
+
+    dmsg(D_REL_LOW, "ACK acknowledge ID " packet_id_format " FAILED (ack->len=%d)",
+         (packet_id_print_type)pid, ack->len);
+    return false;
+}
+
+/* read a packet ID acknowledgement record from buf into ack */
+bool
+reliable_ack_read(struct reliable_ack *ack,
+                  struct buffer *buf, const struct session_id *sid)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    uint8_t count;
+    packet_id_type net_pid;
+    packet_id_type pid;
+    struct session_id session_id_remote;
+
+    if (!buf_read(buf, &count, sizeof(count)))
+    {
+        goto error;
+    }
+    for (i = 0; i < count; ++i)
+    {
+        if (!buf_read(buf, &net_pid, sizeof(net_pid)))
+        {
+            goto error;
+        }
+        if (ack->len >= RELIABLE_ACK_SIZE)
+        {
+            goto error;
+        }
+        pid = ntohpid(net_pid);
+        ack->packet_id[ack->len++] = pid;
+    }
+    if (count)
+    {
+        if (!session_id_read(&session_id_remote, buf))
+        {
+            goto error;
+        }
+        if (!session_id_defined(&session_id_remote)
+            || !session_id_equal(&session_id_remote, sid))
+        {
+            dmsg(D_REL_LOW,
+                 "ACK read BAD SESSION-ID FROM REMOTE, local=%s, remote=%s",
+                 session_id_print(sid, &gc), session_id_print(&session_id_remote, &gc));
+            goto error;
+        }
+    }
+    gc_free(&gc);
+    return true;
+
+error:
+    gc_free(&gc);
+    return false;
+}
+
+#define ACK_SIZE(n) (sizeof(uint8_t) + ((n) ? SID_SIZE : 0) + sizeof(packet_id_type) * (n))
+
+/* write a packet ID acknowledgement record to buf, */
+/* removing all acknowledged entries from ack */
+bool
+reliable_ack_write(struct reliable_ack *ack,
+                   struct buffer *buf,
+                   const struct session_id *sid, int max, bool prepend)
+{
+    int i, j;
+    uint8_t n;
+    struct buffer sub;
+
+    n = ack->len;
+    if (n > max)
+    {
+        n = max;
+    }
+    sub = buf_sub(buf, ACK_SIZE(n), prepend);
+    if (!BDEF(&sub))
+    {
+        goto error;
+    }
+    ASSERT(buf_write(&sub, &n, sizeof(n)));
+    for (i = 0; i < n; ++i)
+    {
+        packet_id_type pid = ack->packet_id[i];
+        packet_id_type net_pid = htonpid(pid);
+        ASSERT(buf_write(&sub, &net_pid, sizeof(net_pid)));
+        dmsg(D_REL_DEBUG, "ACK write ID " packet_id_format " (ack->len=%d, n=%d)", (packet_id_print_type)pid, ack->len, n);
+    }
+    if (n)
+    {
+        ASSERT(session_id_defined(sid));
+        ASSERT(session_id_write(sid, &sub));
+        for (i = 0, j = n; j < ack->len; )
+        {
+            ack->packet_id[i++] = ack->packet_id[j++];
+        }
+        ack->len = i;
+    }
+
+    return true;
+
+error:
+    return false;
+}
+
+/* add to extra_frame the maximum number of bytes we will need for reliable_ack_write */
+void
+reliable_ack_adjust_frame_parameters(struct frame *frame, int max)
+{
+    frame_add_to_extra_frame(frame, ACK_SIZE(max));
+}
+
+/* print a reliable ACK record coming off the wire */
+const char *
+reliable_ack_print(struct buffer *buf, bool verbose, struct gc_arena *gc)
+{
+    int i;
+    uint8_t n_ack;
+    struct session_id sid_ack;
+    packet_id_type pid;
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    buf_printf(&out, "[");
+    if (!buf_read(buf, &n_ack, sizeof(n_ack)))
+    {
+        goto done;
+    }
+    for (i = 0; i < n_ack; ++i)
+    {
+        if (!buf_read(buf, &pid, sizeof(pid)))
+        {
+            goto done;
+        }
+        pid = ntohpid(pid);
+        buf_printf(&out, " " packet_id_format, (packet_id_print_type)pid);
+    }
+    if (n_ack)
+    {
+        if (!session_id_read(&sid_ack, buf))
+        {
+            goto done;
+        }
+        if (verbose)
+        {
+            buf_printf(&out, " sid=%s", session_id_print(&sid_ack, gc));
+        }
+    }
+
+done:
+    buf_printf(&out, " ]");
+    return BSTR(&out);
+}
+
+/*
+ * struct reliable member functions.
+ */
+
+void
+reliable_init(struct reliable *rel, int buf_size, int offset, int array_size, bool hold)
+{
+    int i;
+
+    CLEAR(*rel);
+    ASSERT(array_size > 0 && array_size <= RELIABLE_CAPACITY);
+    rel->hold = hold;
+    rel->size = array_size;
+    rel->offset = offset;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        e->buf = alloc_buf(buf_size);
+        ASSERT(buf_init(&e->buf, offset));
+    }
+}
+
+void
+reliable_free(struct reliable *rel)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        free_buf(&e->buf);
+    }
+}
+
+/* no active buffers? */
+bool
+reliable_empty(const struct reliable *rel)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+/* del acknowledged items from send buf */
+void
+reliable_send_purge(struct reliable *rel, struct reliable_ack *ack)
+{
+    int i, j;
+    for (i = 0; i < ack->len; ++i)
+    {
+        packet_id_type pid = ack->packet_id[i];
+        for (j = 0; j < rel->size; ++j)
+        {
+            struct reliable_entry *e = &rel->array[j];
+            if (e->active && e->packet_id == pid)
+            {
+                dmsg(D_REL_DEBUG,
+                     "ACK received for pid " packet_id_format ", deleting from send buffer",
+                     (packet_id_print_type)pid);
+#if 0
+                /* DEBUGGING -- how close were we timing out on ACK failure and resending? */
+                {
+                    if (e->next_try)
+                    {
+                        const interval_t wake = e->next_try - now;
+                        msg(M_INFO, "ACK " packet_id_format ", wake=%d", pid, wake);
+                    }
+                }
+#endif
+                e->active = false;
+                break;
+            }
+        }
+    }
+}
+
+/* print the current sequence of active packet IDs */
+static const char *
+reliable_print_ids(const struct reliable *rel, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    int i;
+
+    buf_printf(&out, "[" packet_id_format "]", (packet_id_print_type)rel->packet_id);
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            buf_printf(&out, " " packet_id_format, (packet_id_print_type)e->packet_id);
+        }
+    }
+    return BSTR(&out);
+}
+
+/* true if at least one free buffer available */
+bool
+reliable_can_get(const struct reliable *rel)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (!e->active)
+        {
+            return true;
+        }
+    }
+    dmsg(D_REL_LOW, "ACK no free receive buffer available: %s", reliable_print_ids(rel, &gc));
+    gc_free(&gc);
+    return false;
+}
+
+/* make sure that incoming packet ID isn't a replay */
+bool
+reliable_not_replay(const struct reliable *rel, packet_id_type id)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    if (reliable_pid_min(id, rel->packet_id))
+    {
+        goto bad;
+    }
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active && e->packet_id == id)
+        {
+            goto bad;
+        }
+    }
+    gc_free(&gc);
+    return true;
+
+bad:
+    dmsg(D_REL_DEBUG, "ACK " packet_id_format " is a replay: %s", (packet_id_print_type)id, reliable_print_ids(rel, &gc));
+    gc_free(&gc);
+    return false;
+}
+
+/* make sure that incoming packet ID won't deadlock the receive buffer */
+bool
+reliable_wont_break_sequentiality(const struct reliable *rel, packet_id_type id)
+{
+    struct gc_arena gc = gc_new();
+
+    const int ret = reliable_pid_in_range2(id, rel->packet_id, rel->size);
+
+    if (!ret)
+    {
+        dmsg(D_REL_LOW, "ACK " packet_id_format " breaks sequentiality: %s",
+             (packet_id_print_type)id, reliable_print_ids(rel, &gc));
+    }
+
+    dmsg(D_REL_DEBUG, "ACK RWBS rel->size=%d rel->packet_id=%08x id=%08x ret=%d\n", rel->size, rel->packet_id, id, ret);
+
+    gc_free(&gc);
+    return ret;
+}
+
+/* grab a free buffer */
+struct buffer *
+reliable_get_buf(struct reliable *rel)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (!e->active)
+        {
+            ASSERT(buf_init(&e->buf, rel->offset));
+            return &e->buf;
+        }
+    }
+    return NULL;
+}
+
+/* grab a free buffer, fail if buffer clogged by unacknowledged low packet IDs */
+struct buffer *
+reliable_get_buf_output_sequenced(struct reliable *rel)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    packet_id_type min_id = 0;
+    bool min_id_defined = false;
+    struct buffer *ret = NULL;
+
+    /* find minimum active packet_id */
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            if (!min_id_defined || reliable_pid_min(e->packet_id, min_id))
+            {
+                min_id_defined = true;
+                min_id = e->packet_id;
+            }
+        }
+    }
+
+    if (!min_id_defined || reliable_pid_in_range1(rel->packet_id, min_id, rel->size))
+    {
+        ret = reliable_get_buf(rel);
+    }
+    else
+    {
+        dmsg(D_REL_LOW, "ACK output sequence broken: %s", reliable_print_ids(rel, &gc));
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+/* get active buffer for next sequentially increasing key ID */
+struct buffer *
+reliable_get_buf_sequenced(struct reliable *rel)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (e->active && e->packet_id == rel->packet_id)
+        {
+            return &e->buf;
+        }
+    }
+    return NULL;
+}
+
+/* return true if reliable_send would return a non-NULL result */
+bool
+reliable_can_send(const struct reliable *rel)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    int n_active = 0, n_current = 0;
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            ++n_active;
+            if (now >= e->next_try)
+            {
+                ++n_current;
+            }
+        }
+    }
+    dmsg(D_REL_DEBUG, "ACK reliable_can_send active=%d current=%d : %s",
+         n_active,
+         n_current,
+         reliable_print_ids(rel, &gc));
+
+    gc_free(&gc);
+    return n_current > 0 && !rel->hold;
+}
+
+#ifdef EXPONENTIAL_BACKOFF
+/* return a unique point-in-time to trigger retry */
+static time_t
+reliable_unique_retry(struct reliable *rel, time_t retry)
+{
+    int i;
+    while (true)
+    {
+        for (i = 0; i < rel->size; ++i)
+        {
+            struct reliable_entry *e = &rel->array[i];
+            if (e->active && e->next_try == retry)
+            {
+                goto again;
+            }
+        }
+        break;
+again:
+        ++retry;
+    }
+    return retry;
+}
+#endif /* ifdef EXPONENTIAL_BACKOFF */
+
+/* return next buffer to send to remote */
+struct buffer *
+reliable_send(struct reliable *rel, int *opcode)
+{
+    int i;
+    struct reliable_entry *best = NULL;
+    const time_t local_now = now;
+
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (e->active && local_now >= e->next_try)
+        {
+            if (!best || reliable_pid_min(e->packet_id, best->packet_id))
+            {
+                best = e;
+            }
+        }
+    }
+    if (best)
+    {
+#ifdef EXPONENTIAL_BACKOFF
+        /* exponential backoff */
+        best->next_try = reliable_unique_retry(rel, local_now + best->timeout);
+        best->timeout *= 2;
+#else
+        /* constant timeout, no backoff */
+        best->next_try = local_now + best->timeout;
+#endif
+        *opcode = best->opcode;
+        dmsg(D_REL_DEBUG, "ACK reliable_send ID " packet_id_format " (size=%d to=%d)",
+             (packet_id_print_type)best->packet_id, best->buf.len,
+             (int)(best->next_try - local_now));
+        return &best->buf;
+    }
+    return NULL;
+}
+
+/* schedule all pending packets for immediate retransmit */
+void
+reliable_schedule_now(struct reliable *rel)
+{
+    int i;
+    dmsg(D_REL_DEBUG, "ACK reliable_schedule_now");
+    rel->hold = false;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            e->next_try = now;
+            e->timeout = rel->initial_timeout;
+        }
+    }
+}
+
+/* in how many seconds should we wake up to check for timeout */
+/* if we return BIG_TIMEOUT, nothing to wait for */
+interval_t
+reliable_send_timeout(const struct reliable *rel)
+{
+    struct gc_arena gc = gc_new();
+    interval_t ret = BIG_TIMEOUT;
+    int i;
+    const time_t local_now = now;
+
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            if (e->next_try <= local_now)
+            {
+                ret = 0;
+                break;
+            }
+            else
+            {
+                ret = min_int(ret, e->next_try - local_now);
+            }
+        }
+    }
+
+    dmsg(D_REL_DEBUG, "ACK reliable_send_timeout %d %s",
+         (int) ret,
+         reliable_print_ids(rel, &gc));
+
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Enable an incoming buffer previously returned by a get function as active.
+ */
+
+void
+reliable_mark_active_incoming(struct reliable *rel, struct buffer *buf,
+                              packet_id_type pid, int opcode)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (buf == &e->buf)
+        {
+            e->active = true;
+
+            /* packets may not arrive in sequential order */
+            e->packet_id = pid;
+
+            /* check for replay */
+            ASSERT(!reliable_pid_min(pid, rel->packet_id));
+
+            e->opcode = opcode;
+            e->next_try = 0;
+            e->timeout = 0;
+            dmsg(D_REL_DEBUG, "ACK mark active incoming ID " packet_id_format, (packet_id_print_type)e->packet_id);
+            return;
+        }
+    }
+    ASSERT(0);                  /* buf not found in rel */
+}
+
+/*
+ * Enable an outgoing buffer previously returned by a get function as active.
+ */
+
+void
+reliable_mark_active_outgoing(struct reliable *rel, struct buffer *buf, int opcode)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (buf == &e->buf)
+        {
+            /* Write mode, increment packet_id (i.e. sequence number)
+             * linearly and prepend id to packet */
+            packet_id_type net_pid;
+            e->packet_id = rel->packet_id++;
+            net_pid = htonpid(e->packet_id);
+            ASSERT(buf_write_prepend(buf, &net_pid, sizeof(net_pid)));
+            e->active = true;
+            e->opcode = opcode;
+            e->next_try = 0;
+            e->timeout = rel->initial_timeout;
+            dmsg(D_REL_DEBUG, "ACK mark active outgoing ID " packet_id_format, (packet_id_print_type)e->packet_id);
+            return;
+        }
+    }
+    ASSERT(0);                  /* buf not found in rel */
+}
+
+/* delete a buffer previously activated by reliable_mark_active() */
+void
+reliable_mark_deleted(struct reliable *rel, struct buffer *buf, bool inc_pid)
+{
+    int i;
+    for (i = 0; i < rel->size; ++i)
+    {
+        struct reliable_entry *e = &rel->array[i];
+        if (buf == &e->buf)
+        {
+            e->active = false;
+            if (inc_pid)
+            {
+                rel->packet_id = e->packet_id + 1;
+            }
+            return;
+        }
+    }
+    ASSERT(0);
+}
+
+#if 0
+
+void
+reliable_ack_debug_print(const struct reliable_ack *ack, char *desc)
+{
+    int i;
+
+    printf("********* struct reliable_ack %s\n", desc);
+    for (i = 0; i < ack->len; ++i)
+    {
+        printf("  %d: " packet_id_format "\n", i, (packet_id_print_type) ack->packet_id[i]);
+    }
+}
+
+void
+reliable_debug_print(const struct reliable *rel, char *desc)
+{
+    int i;
+    update_time();
+
+    printf("********* struct reliable %s\n", desc);
+    printf("  initial_timeout=%d\n", (int)rel->initial_timeout);
+    printf("  packet_id=" packet_id_format "\n", rel->packet_id);
+    printf("  now=" time_format "\n", now);
+    for (i = 0; i < rel->size; ++i)
+    {
+        const struct reliable_entry *e = &rel->array[i];
+        if (e->active)
+        {
+            printf("  %d: packet_id=" packet_id_format " len=%d", i, e->packet_id, e->buf.len);
+            printf(" next_try=" time_format, e->next_try);
+            printf("\n");
+        }
+    }
+}
+
+#endif /* if 0 */
+
+#else  /* ifdef ENABLE_CRYPTO */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/reliable.h b/src/openvpn/reliable.h
new file mode 100644
index 0000000..bc32ad9
--- /dev/null
+++ b/src/openvpn/reliable.h
@@ -0,0 +1,479 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+
+/**
+ * @file
+ * Reliability Layer module header file.
+ */
+
+
+#ifdef ENABLE_CRYPTO
+
+#ifndef RELIABLE_H
+#define RELIABLE_H
+
+#include "basic.h"
+#include "buffer.h"
+#include "packet_id.h"
+#include "session_id.h"
+#include "mtu.h"
+
+/** @addtogroup reliable
+ *  @{ */
+
+
+#define EXPONENTIAL_BACKOFF
+
+#define RELIABLE_ACK_SIZE 8     /**< The maximum number of packet IDs
+                                 *   waiting to be acknowledged which can
+                                 *   be stored in one \c reliable_ack
+                                 *   structure. */
+
+#define RELIABLE_CAPACITY 8     /**< The maximum number of packets that
+                                 *   the reliability layer for one VPN
+                                 *   tunnel in one direction can store. */
+
+/**
+ * The acknowledgment structure in which packet IDs are stored for later
+ * acknowledgment.
+ */
+struct reliable_ack
+{
+    int len;
+    packet_id_type packet_id[RELIABLE_ACK_SIZE];
+};
+
+/**
+ * The structure in which the reliability layer stores a single incoming
+ * or outgoing packet.
+ */
+struct reliable_entry
+{
+    bool active;
+    interval_t timeout;
+    time_t next_try;
+    packet_id_type packet_id;
+    int opcode;
+    struct buffer buf;
+};
+
+/**
+ * The reliability layer storage structure for one VPN tunnel's control
+ * channel in one direction.
+ */
+struct reliable
+{
+    int size;
+    interval_t initial_timeout;
+    packet_id_type packet_id;
+    int offset;
+    bool hold; /* don't xmit until reliable_schedule_now is called */
+    struct reliable_entry array[RELIABLE_CAPACITY];
+};
+
+
+/**************************************************************************/
+/** @name Functions for processing incoming acknowledgments
+ *  @{ */
+
+/**
+ * Read an acknowledgment record from a received packet.
+ *
+ * This function reads the packet ID acknowledgment record from the packet
+ * contained in \a buf.  If the record contains acknowledgments, these are
+ * stored in \a ack.  This function also compares the packet's session ID
+ * with the expected session ID \a sid, which should be equal.
+ *
+ * @param ack The acknowledgment structure in which received
+ *     acknowledgments are to be stored.
+ * @param buf The buffer containing the packet.
+ * @param sid The expected session ID to compare to the session ID in
+ *     the packet.
+ *
+ * @return
+ * @li True, if processing was successful.
+ * @li False, if an error occurs during processing.
+ */
+bool reliable_ack_read(struct reliable_ack *ack,
+                       struct buffer *buf, const struct session_id *sid);
+
+/**
+ * Remove acknowledged packets from a reliable structure.
+ *
+ * @param rel The reliable structure storing sent packets.
+ * @param ack The acknowledgment structure containing received
+ *     acknowledgments.
+ */
+void reliable_send_purge(struct reliable *rel, struct reliable_ack *ack);
+
+/** @} name Functions for processing incoming acknowledgments */
+
+
+/**************************************************************************/
+/** @name Functions for processing outgoing acknowledgments
+ *  @{ */
+
+/**
+ * Check whether an acknowledgment structure contains any
+ *     packet IDs to be acknowledged.
+ *
+ * @param ack The acknowledgment structure to check.
+ *
+ * @return
+ * @li True, if the acknowledgment structure is empty.
+ * @li False, if there are packet IDs to be acknowledged.
+ */
+static inline bool
+reliable_ack_empty(struct reliable_ack *ack)
+{
+    return !ack->len;
+}
+
+/**
+ * Write a packet ID acknowledgment record to a buffer.
+ *
+ * @param ack The acknowledgment structure containing packet IDs to be
+ *     acknowledged.
+ * @param buf The buffer into which the acknowledgment record will be
+ *     written.
+ * @param sid The session ID of the VPN tunnel associated with the
+ *     packet IDs to be acknowledged.
+ * @param max The maximum number of acknowledgments to be written in
+ *     the record.
+ * @param prepend If true, prepend the acknowledgment record in the
+ *     buffer; if false, write into the buffer's current position.
+ *
+ * @return
+ * @li True, if processing was successful.
+ * @li False, if an error occurs during processing.
+ */
+bool reliable_ack_write(struct reliable_ack *ack,
+                        struct buffer *buf,
+                        const struct session_id *sid, int max, bool prepend);
+
+/** @} name Functions for processing outgoing acknowledgments */
+
+
+/**************************************************************************/
+/** @name Functions for initialization and cleanup
+ *  @{ */
+
+/**
+ * Initialize a reliable structure.
+ *
+ * @param rel The reliable structure to initialize.
+ * @param buf_size The size of the buffers in which packets will be
+ *     stored.
+ * @param offset The size of reserved space at the beginning of the
+ *     buffers to allow efficient header prepending.
+ * @param array_size The number of packets that this reliable
+ *     structure can store simultaneously.
+ * @param hold description
+ */
+void reliable_init(struct reliable *rel, int buf_size, int offset, int array_size, bool hold);
+
+/**
+ * Free allocated memory associated with a reliable structure.
+ *
+ * @param rel The reliable structured to clean up.
+ */
+void reliable_free(struct reliable *rel);
+
+/* add to extra_frame the maximum number of bytes we will need for reliable_ack_write */
+void reliable_ack_adjust_frame_parameters(struct frame *frame, int max);
+
+/** @} name Functions for initialization and cleanup */
+
+
+/**************************************************************************/
+/** @name Functions for inserting incoming packets
+ *  @{ */
+
+/**
+ * Check whether a reliable structure has any free buffers
+ *     available for use.
+ *
+ * @param rel The reliable structure to check.
+ *
+ * @return
+ * @li True, if at least one buffer is available for use.
+ * @li False, if all the buffers are active.
+ */
+bool reliable_can_get(const struct reliable *rel);
+
+/**
+ * Check that a received packet's ID is not a replay.
+ *
+ * @param rel The reliable structure for handling this VPN tunnel's
+ *     received packets.
+ * @param id The packet ID of the received packet.
+ *
+ * @return
+ * @li True, if the packet ID is not a replay.
+ * @li False, if the packet ID is a replay.
+ */
+bool reliable_not_replay(const struct reliable *rel, packet_id_type id);
+
+/**
+ * Check that a received packet's ID can safely be stored in
+ *     the reliable structure's processing window.
+ *
+ * This function checks the difference between the received packet's ID
+ * and the lowest non-acknowledged packet ID in the given reliable
+ * structure.  If that difference is larger than the total number of
+ * packets which can be stored, then this packet cannot be stored safely,
+ * because the reliable structure could possibly fill up without leaving
+ * room for all intervening packets.  In that case, this received packet
+ * could break the reliable structure's sequentiality, and must therefore
+ * be discarded.
+ *
+ * @param rel The reliable structure for handling this VPN tunnel's
+ *     received packets.
+ * @param id The packet ID of the received packet.
+ *
+ * @return
+ * @li True, if the packet can safely be stored.
+ * @li False, if the packet does not fit safely in the reliable
+ *     structure's processing window.
+ */
+bool reliable_wont_break_sequentiality(const struct reliable *rel, packet_id_type id);
+
+/**
+ * Read the packet ID of a received packet.
+ *
+ * @param buf The buffer containing the received packet.
+ * @param pid A pointer where the packet's packet ID will be written.
+ *
+ * @return
+ * @li True, if processing was successful.
+ * @li False, if an error occurs during processing.
+ */
+bool reliable_ack_read_packet_id(struct buffer *buf, packet_id_type *pid);
+
+/**
+ * Get the buffer of a free %reliable entry in which to store a
+ *     packet.
+ *
+ * @param rel The reliable structure in which to search for a free
+ *     entry.
+ *
+ * @return A pointer to a buffer of a free entry in the \a rel
+ *     reliable structure.  If there are no free entries available, this
+ *     function returns NULL.
+ */
+struct buffer *reliable_get_buf(struct reliable *rel);
+
+/**
+ * Mark the %reliable entry associated with the given buffer as active
+ * incoming.
+ *
+ * @param rel The reliable structure associated with this packet.
+ * @param buf The buffer into which the packet has been copied.
+ * @param pid The packet's packet ID.
+ * @param opcode The packet's opcode.
+ */
+void reliable_mark_active_incoming(struct reliable *rel, struct buffer *buf,
+                                   packet_id_type pid, int opcode);
+
+/**
+ * Record a packet ID for later acknowledgment.
+ *
+ * @param ack The acknowledgment structure which stores this VPN
+ *     tunnel's packet IDs for later acknowledgment.
+ * @param pid The packet ID of the received packet which should be
+ *     acknowledged.
+ *
+ * @return
+ * @li True, if the packet ID was added to \a ack.
+ * @li False, if the packet ID was already present in \a ack or \a ack
+ *     has no free space to store any more packet IDs.
+ */
+bool reliable_ack_acknowledge_packet_id(struct reliable_ack *ack, packet_id_type pid);
+
+/** @} name Functions for inserting incoming packets */
+
+
+/**************************************************************************/
+/** @name Functions for extracting incoming packets
+ *  @{ */
+
+/**
+ * Get the buffer of the next sequential and active entry.
+ *
+ * @param rel The reliable structure from which to retrieve the
+ *     buffer.
+ *
+ * @return A pointer to the buffer of the entry with the next
+ *     sequential key ID.  If no such entry is present, this function
+ *     returns NULL.
+ */
+struct buffer *reliable_get_buf_sequenced(struct reliable *rel);
+
+/**
+ * Remove an entry from a reliable structure.
+ *
+ * @param rel The reliable structure associated with the given buffer.
+ * @param buf The buffer of the reliable entry which is to be removed.
+ * @param inc_pid If true, the reliable structure's packet ID counter
+ *     will be incremented.
+ */
+void reliable_mark_deleted(struct reliable *rel, struct buffer *buf, bool inc_pid);
+
+/** @} name Functions for extracting incoming packets */
+
+
+/**************************************************************************/
+/** @name Functions for inserting outgoing packets
+ *  @{ */
+
+/**
+ * Get the buffer of free reliable entry and check whether the
+ *     outgoing acknowledgment sequence is still okay.
+ *
+ * @param rel The reliable structure in which to search for a free
+ *     entry.
+ *
+ * @return A pointer to a buffer of a free entry in the \a rel
+ *     reliable structure.  If there are no free entries available, this
+ *     function returns NULL.  If the outgoing acknowledgment sequence is
+ *     broken, this function also returns NULL.
+ */
+struct buffer *reliable_get_buf_output_sequenced(struct reliable *rel);
+
+/**
+ * Mark the reliable entry associated with the given buffer as
+ *     active outgoing.
+ *
+ * @param rel The reliable structure for handling this VPN tunnel's
+ *     outgoing packets.
+ * @param buf The buffer previously returned by \c
+ *     reliable_get_buf_output_sequenced() into which the packet has been
+ *     copied.
+ * @param opcode The packet's opcode.
+ */
+void reliable_mark_active_outgoing(struct reliable *rel, struct buffer *buf, int opcode);
+
+/** @} name Functions for inserting outgoing packets */
+
+
+/**************************************************************************/
+/** @name Functions for extracting outgoing packets
+ *  @{ */
+
+/**
+ * Check whether a reliable structure has any active entries
+ *     ready to be (re)sent.
+ *
+ * @param rel The reliable structure to check.
+ *
+ * @return
+ * @li True, if there are active entries ready to be (re)sent
+ *     president.
+ * @li False, if there are no active entries, or the active entries
+ *     are not yet ready for resending.
+ */
+bool reliable_can_send(const struct reliable *rel);
+
+/**
+ * Get the next packet to send to the remote peer.
+ *
+ * This function looks for the active entry ready for (re)sending with the
+ * lowest packet ID, and returns the buffer associated with it.  This
+ * function also resets the timeout after which that entry will become
+ * ready for resending again.
+ *
+ * @param rel The reliable structure to check.
+ * @param opcode A pointer to an integer in which this function will
+ *     store the opcode of the next packet to be sent.
+ *
+ * @return A pointer to the buffer of the next entry to be sent, or
+ *     NULL if there are no entries ready for (re)sending present in the
+ *     reliable structure.  If a valid pointer is returned, then \a opcode
+ *     will point to the opcode of that packet.
+ */
+struct buffer *reliable_send(struct reliable *rel, int *opcode);
+
+/** @} name Functions for extracting outgoing packets */
+
+
+/**************************************************************************/
+/** @name Miscellaneous functions
+ *  @{ */
+
+/**
+ * Check whether a reliable structure is empty.
+ *
+ * @param rel The reliable structure to check.
+ *
+ * @return
+ * @li True, if there are no active entries in the given reliable
+ *     structure.
+ * @li False, if there is at least one active entry present.
+ */
+bool reliable_empty(const struct reliable *rel);
+
+/**
+ * Determined how many seconds until the earliest resend should
+ *     be attempted.
+ *
+ * @param rel The reliable structured to check.
+ *
+ * @return The interval in seconds until the earliest resend attempt
+ *     of the outgoing packets stored in the \a rel reliable structure. If
+ *     the next time for attempting resending of one or more packets has
+ *     already passed, this function will return 0.
+ */
+interval_t reliable_send_timeout(const struct reliable *rel);
+
+/**
+ * Reschedule all entries of a reliable structure to be ready
+ *     for (re)sending immediately.
+ *
+ * @param rel The reliable structure of which the entries should be
+ *     modified.
+ */
+void reliable_schedule_now(struct reliable *rel);
+
+void reliable_debug_print(const struct reliable *rel, char *desc);
+
+/* set sending timeout (after this time we send again until ACK) */
+static inline void
+reliable_set_timeout(struct reliable *rel, interval_t timeout)
+{
+    rel->initial_timeout = timeout;
+}
+
+/* print a reliable ACK record coming off the wire */
+const char *reliable_ack_print(struct buffer *buf, bool verbose, struct gc_arena *gc);
+
+void reliable_ack_debug_print(const struct reliable_ack *ack, char *desc);
+
+/** @} name Miscellaneous functions */
+
+
+/** @} addtogroup reliable */
+
+
+#endif /* RELIABLE_H */
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/route.c b/src/openvpn/route.c
new file mode 100644
index 0000000..4199da3
--- /dev/null
+++ b/src/openvpn/route.c
@@ -0,0 +1,4186 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Support routines for adding/deleting network routes.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "error.h"
+#include "route.h"
+#include "misc.h"
+#include "socket.h"
+#include "manage.h"
+#include "win32.h"
+#include "options.h"
+
+#include "memdbg.h"
+
+#if defined(TARGET_LINUX) || defined(TARGET_ANDROID)
+#include <linux/rtnetlink.h>            /* RTM_GETROUTE etc. */
+#endif
+
+#ifdef _WIN32
+#include "openvpn-msg.h"
+
+#define METRIC_NOT_USED ((DWORD)-1)
+static bool add_route_service(const struct route_ipv4 *, const struct tuntap *);
+
+static bool del_route_service(const struct route_ipv4 *, const struct tuntap *);
+
+static bool add_route_ipv6_service(const struct route_ipv6 *, const struct tuntap *);
+
+static bool del_route_ipv6_service(const struct route_ipv6 *, const struct tuntap *);
+
+#endif
+
+static void delete_route(struct route_ipv4 *r, const struct tuntap *tt, unsigned int flags, const struct route_gateway_info *rgi, const struct env_set *es);
+
+static void get_bypass_addresses(struct route_bypass *rb, const unsigned int flags);
+
+#ifdef ENABLE_DEBUG
+
+static void
+print_bypass_addresses(const struct route_bypass *rb)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    for (i = 0; i < rb->n_bypass; ++i)
+    {
+        msg(D_ROUTE, "ROUTE: bypass_host_route[%d]=%s",
+            i,
+            print_in_addr_t(rb->bypass[i], 0, &gc));
+    }
+    gc_free(&gc);
+}
+
+#endif
+
+static bool
+add_bypass_address(struct route_bypass *rb, const in_addr_t a)
+{
+    int i;
+    for (i = 0; i < rb->n_bypass; ++i)
+    {
+        if (a == rb->bypass[i]) /* avoid duplicates */
+        {
+            return true;
+        }
+    }
+    if (rb->n_bypass < N_ROUTE_BYPASS)
+    {
+        rb->bypass[rb->n_bypass++] = a;
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+struct route_option_list *
+new_route_option_list(struct gc_arena *a)
+{
+    struct route_option_list *ret;
+    ALLOC_OBJ_CLEAR_GC(ret, struct route_option_list, a);
+    ret->gc = a;
+    return ret;
+}
+
+struct route_ipv6_option_list *
+new_route_ipv6_option_list(struct gc_arena *a)
+{
+    struct route_ipv6_option_list *ret;
+    ALLOC_OBJ_CLEAR_GC(ret, struct route_ipv6_option_list, a);
+    ret->gc = a;
+    return ret;
+}
+
+/*
+ * NOTE: structs are cloned/copied shallow by design.
+ * The routes list from src will stay intact since it is allocated using
+ * the options->gc. The cloned/copied lists will share this common tail
+ * to avoid copying the data around between pulls. Pulled routes use
+ * the c2->gc so they get freed immediately after a reconnect.
+ */
+struct route_option_list *
+clone_route_option_list(const struct route_option_list *src, struct gc_arena *a)
+{
+    struct route_option_list *ret;
+    ALLOC_OBJ_GC(ret, struct route_option_list, a);
+    *ret = *src;
+    return ret;
+}
+
+struct route_ipv6_option_list *
+clone_route_ipv6_option_list(const struct route_ipv6_option_list *src, struct gc_arena *a)
+{
+    struct route_ipv6_option_list *ret;
+    ALLOC_OBJ_GC(ret, struct route_ipv6_option_list, a);
+    *ret = *src;
+    return ret;
+}
+
+void
+copy_route_option_list(struct route_option_list *dest, const struct route_option_list *src, struct gc_arena *a)
+{
+    *dest = *src;
+    dest->gc = a;
+}
+
+void
+copy_route_ipv6_option_list(struct route_ipv6_option_list *dest,
+                            const struct route_ipv6_option_list *src,
+                            struct gc_arena *a)
+{
+    *dest = *src;
+    dest->gc = a;
+}
+
+static const char *
+route_string(const struct route_ipv4 *r, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    buf_printf(&out, "ROUTE network %s netmask %s gateway %s",
+               print_in_addr_t(r->network, 0, gc),
+               print_in_addr_t(r->netmask, 0, gc),
+               print_in_addr_t(r->gateway, 0, gc)
+               );
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        buf_printf(&out, " metric %d", r->metric);
+    }
+    return BSTR(&out);
+}
+
+static bool
+is_route_parm_defined(const char *parm)
+{
+    if (!parm)
+    {
+        return false;
+    }
+    if (!strcmp(parm, "default"))
+    {
+        return false;
+    }
+    return true;
+}
+
+static void
+setenv_route_addr(struct env_set *es, const char *key, const in_addr_t addr, int i)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer name = alloc_buf_gc(256, &gc);
+    if (i >= 0)
+    {
+        buf_printf(&name, "route_%s_%d", key, i);
+    }
+    else
+    {
+        buf_printf(&name, "route_%s", key);
+    }
+    setenv_str(es, BSTR(&name), print_in_addr_t(addr, 0, &gc));
+    gc_free(&gc);
+}
+
+static bool
+get_special_addr(const struct route_list *rl,
+                 const char *string,
+                 in_addr_t *out,
+                 bool *status)
+{
+    if (status)
+    {
+        *status = true;
+    }
+    if (!strcmp(string, "vpn_gateway"))
+    {
+        if (rl)
+        {
+            if (rl->spec.flags & RTSA_REMOTE_ENDPOINT)
+            {
+                *out = rl->spec.remote_endpoint;
+            }
+            else
+            {
+                msg(M_INFO, PACKAGE_NAME " ROUTE: vpn_gateway undefined");
+                if (status)
+                {
+                    *status = false;
+                }
+            }
+        }
+        return true;
+    }
+    else if (!strcmp(string, "net_gateway"))
+    {
+        if (rl)
+        {
+            if (rl->rgi.flags & RGI_ADDR_DEFINED)
+            {
+                *out = rl->rgi.gateway.addr;
+            }
+            else
+            {
+                msg(M_INFO, PACKAGE_NAME " ROUTE: net_gateway undefined -- unable to get default gateway from system");
+                if (status)
+                {
+                    *status = false;
+                }
+            }
+        }
+        return true;
+    }
+    else if (!strcmp(string, "remote_host"))
+    {
+        if (rl)
+        {
+            if (rl->spec.flags & RTSA_REMOTE_HOST)
+            {
+                *out = rl->spec.remote_host;
+            }
+            else
+            {
+                msg(M_INFO, PACKAGE_NAME " ROUTE: remote_host undefined");
+                if (status)
+                {
+                    *status = false;
+                }
+            }
+        }
+        return true;
+    }
+    return false;
+}
+
+bool
+is_special_addr(const char *addr_str)
+{
+    if (addr_str)
+    {
+        return get_special_addr(NULL, addr_str, NULL, NULL);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static bool
+init_route(struct route_ipv4 *r,
+           struct addrinfo **network_list,
+           const struct route_option *ro,
+           const struct route_list *rl)
+{
+    const in_addr_t default_netmask = IPV4_NETMASK_HOST;
+    bool status;
+    int ret;
+    struct in_addr special;
+
+    CLEAR(*r);
+    r->option = ro;
+
+    /* network */
+
+    if (!is_route_parm_defined(ro->network))
+    {
+        goto fail;
+    }
+
+
+    /* get_special_addr replaces specialaddr with a special ip addr
+     * like gw. getaddrinfo is called to convert a a addrinfo struct */
+
+    if (get_special_addr(rl, ro->network, (in_addr_t *) &special.s_addr, &status))
+    {
+        special.s_addr = htonl(special.s_addr);
+        ret = openvpn_getaddrinfo(0, inet_ntoa(special), NULL, 0, NULL,
+                                  AF_INET, network_list);
+    }
+    else
+    {
+        ret = openvpn_getaddrinfo(GETADDR_RESOLVE | GETADDR_WARN_ON_SIGNAL,
+                                  ro->network, NULL, 0, NULL, AF_INET, network_list);
+    }
+
+    status = (ret == 0);
+
+    if (!status)
+    {
+        goto fail;
+    }
+
+    /* netmask */
+
+    if (is_route_parm_defined(ro->netmask))
+    {
+        r->netmask = getaddr(
+            GETADDR_HOST_ORDER
+            | GETADDR_WARN_ON_SIGNAL,
+            ro->netmask,
+            0,
+            &status,
+            NULL);
+        if (!status)
+        {
+            goto fail;
+        }
+    }
+    else
+    {
+        r->netmask = default_netmask;
+    }
+
+    /* gateway */
+
+    if (is_route_parm_defined(ro->gateway))
+    {
+        if (!get_special_addr(rl, ro->gateway, &r->gateway, &status))
+        {
+            r->gateway = getaddr(
+                GETADDR_RESOLVE
+                | GETADDR_HOST_ORDER
+                | GETADDR_WARN_ON_SIGNAL,
+                ro->gateway,
+                0,
+                &status,
+                NULL);
+        }
+        if (!status)
+        {
+            goto fail;
+        }
+    }
+    else
+    {
+        if (rl->spec.flags & RTSA_REMOTE_ENDPOINT)
+        {
+            r->gateway = rl->spec.remote_endpoint;
+        }
+        else
+        {
+            msg(M_WARN, PACKAGE_NAME " ROUTE: " PACKAGE_NAME " needs a gateway parameter for a --route option and no default was specified by either --route-gateway or --ifconfig options");
+            goto fail;
+        }
+    }
+
+    /* metric */
+
+    r->metric = 0;
+    if (is_route_parm_defined(ro->metric))
+    {
+        r->metric = atoi(ro->metric);
+        if (r->metric < 0)
+        {
+            msg(M_WARN, PACKAGE_NAME " ROUTE: route metric for network %s (%s) must be >= 0",
+                ro->network,
+                ro->metric);
+            goto fail;
+        }
+        r->flags |= RT_METRIC_DEFINED;
+    }
+    else if (rl->spec.flags & RTSA_DEFAULT_METRIC)
+    {
+        r->metric = rl->spec.default_metric;
+        r->flags |= RT_METRIC_DEFINED;
+    }
+
+    r->flags |= RT_DEFINED;
+
+    return true;
+
+fail:
+    msg(M_WARN, PACKAGE_NAME " ROUTE: failed to parse/resolve route for host/network: %s",
+        ro->network);
+    return false;
+}
+
+static bool
+init_route_ipv6(struct route_ipv6 *r6,
+                const struct route_ipv6_option *r6o,
+                const struct route_ipv6_list *rl6 )
+{
+    CLEAR(*r6);
+
+    if (!get_ipv6_addr( r6o->prefix, &r6->network, &r6->netbits, M_WARN ))
+    {
+        goto fail;
+    }
+
+    /* gateway */
+    if (is_route_parm_defined(r6o->gateway))
+    {
+        if (inet_pton( AF_INET6, r6o->gateway, &r6->gateway ) != 1)
+        {
+            msg( M_WARN, PACKAGE_NAME "ROUTE6: cannot parse gateway spec '%s'", r6o->gateway );
+        }
+    }
+    else if (rl6->spec_flags & RTSA_REMOTE_ENDPOINT)
+    {
+        r6->gateway = rl6->remote_endpoint_ipv6;
+    }
+    else
+    {
+        msg(M_WARN, PACKAGE_NAME " ROUTE6: " PACKAGE_NAME " needs a gateway parameter for a --route-ipv6 option and no default was specified by either --route-ipv6-gateway or --ifconfig-ipv6 options");
+        goto fail;
+    }
+
+    /* metric */
+
+    r6->metric = -1;
+    if (is_route_parm_defined(r6o->metric))
+    {
+        r6->metric = atoi(r6o->metric);
+        if (r6->metric < 0)
+        {
+            msg(M_WARN, PACKAGE_NAME " ROUTE: route metric for network %s (%s) must be >= 0",
+                r6o->prefix,
+                r6o->metric);
+            goto fail;
+        }
+        r6->flags |= RT_METRIC_DEFINED;
+    }
+    else if (rl6->spec_flags & RTSA_DEFAULT_METRIC)
+    {
+        r6->metric = rl6->default_metric;
+        r6->flags |= RT_METRIC_DEFINED;
+    }
+
+    r6->flags |= RT_DEFINED;
+
+    return true;
+
+fail:
+    msg(M_WARN, PACKAGE_NAME " ROUTE: failed to parse/resolve route for host/network: %s",
+        r6o->prefix);
+    return false;
+}
+
+void
+add_route_to_option_list(struct route_option_list *l,
+                         const char *network,
+                         const char *netmask,
+                         const char *gateway,
+                         const char *metric)
+{
+    struct route_option *ro;
+    ALLOC_OBJ_GC(ro, struct route_option, l->gc);
+    ro->network = network;
+    ro->netmask = netmask;
+    ro->gateway = gateway;
+    ro->metric = metric;
+    ro->next = l->routes;
+    l->routes = ro;
+
+}
+
+void
+add_route_ipv6_to_option_list(struct route_ipv6_option_list *l,
+                              const char *prefix,
+                              const char *gateway,
+                              const char *metric)
+{
+    struct route_ipv6_option *ro;
+    ALLOC_OBJ_GC(ro, struct route_ipv6_option, l->gc);
+    ro->prefix = prefix;
+    ro->gateway = gateway;
+    ro->metric = metric;
+    ro->next = l->routes_ipv6;
+    l->routes_ipv6 = ro;
+}
+
+static void
+clear_route_list(struct route_list *rl)
+{
+    gc_free(&rl->gc);
+    CLEAR(*rl);
+}
+
+static void
+clear_route_ipv6_list(struct route_ipv6_list *rl6)
+{
+    gc_free(&rl6->gc);
+    CLEAR(*rl6);
+}
+
+void
+route_list_add_vpn_gateway(struct route_list *rl,
+                           struct env_set *es,
+                           const in_addr_t addr)
+{
+    ASSERT(rl);
+    rl->spec.remote_endpoint = addr;
+    rl->spec.flags |= RTSA_REMOTE_ENDPOINT;
+    setenv_route_addr(es, "vpn_gateway", rl->spec.remote_endpoint, -1);
+}
+
+static void
+add_block_local_item(struct route_list *rl,
+                     const struct route_gateway_address *gateway,
+                     in_addr_t target)
+{
+    const int rgi_needed = (RGI_ADDR_DEFINED|RGI_NETMASK_DEFINED);
+    if ((rl->rgi.flags & rgi_needed) == rgi_needed
+        && rl->rgi.gateway.netmask < 0xFFFFFFFF)
+    {
+        struct route_ipv4 *r1, *r2;
+        unsigned int l2;
+
+        ALLOC_OBJ_GC(r1, struct route_ipv4, &rl->gc);
+        ALLOC_OBJ_GC(r2, struct route_ipv4, &rl->gc);
+
+        /* split a route into two smaller blocking routes, and direct them to target */
+        l2 = ((~gateway->netmask)+1)>>1;
+        r1->flags = RT_DEFINED;
+        r1->gateway = target;
+        r1->network = gateway->addr & gateway->netmask;
+        r1->netmask = ~(l2-1);
+        r1->next = rl->routes;
+        rl->routes = r1;
+
+        *r2 = *r1;
+        r2->network += l2;
+        r2->next = rl->routes;
+        rl->routes = r2;
+    }
+}
+
+static void
+add_block_local(struct route_list *rl)
+{
+    const int rgi_needed = (RGI_ADDR_DEFINED|RGI_NETMASK_DEFINED);
+    if ((rl->flags & RG_BLOCK_LOCAL)
+        && (rl->rgi.flags & rgi_needed) == rgi_needed
+        && (rl->spec.flags & RTSA_REMOTE_ENDPOINT)
+        && rl->spec.remote_host_local != TLA_LOCAL)
+    {
+        size_t i;
+
+#ifndef TARGET_ANDROID
+        /* add bypass for gateway addr */
+        add_bypass_address(&rl->spec.bypass, rl->rgi.gateway.addr);
+#endif
+
+        /* block access to local subnet */
+        add_block_local_item(rl, &rl->rgi.gateway, rl->spec.remote_endpoint);
+
+        /* process additional subnets on gateway interface */
+        for (i = 0; i < rl->rgi.n_addrs; ++i)
+        {
+            const struct route_gateway_address *gwa = &rl->rgi.addrs[i];
+            /* omit the add/subnet in &rl->rgi which we processed above */
+            if (!((rl->rgi.gateway.addr & rl->rgi.gateway.netmask) == (gwa->addr & gwa->netmask)
+                  && rl->rgi.gateway.netmask == gwa->netmask))
+            {
+                add_block_local_item(rl, gwa, rl->spec.remote_endpoint);
+            }
+        }
+    }
+}
+
+bool
+init_route_list(struct route_list *rl,
+                const struct route_option_list *opt,
+                const char *remote_endpoint,
+                int default_metric,
+                in_addr_t remote_host,
+                struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = true;
+
+    clear_route_list(rl);
+
+    rl->flags = opt->flags;
+
+    if (remote_host)
+    {
+        rl->spec.remote_host = remote_host;
+        rl->spec.flags |= RTSA_REMOTE_HOST;
+    }
+
+    if (default_metric)
+    {
+        rl->spec.default_metric = default_metric;
+        rl->spec.flags |= RTSA_DEFAULT_METRIC;
+    }
+
+    get_default_gateway(&rl->rgi);
+    if (rl->rgi.flags & RGI_ADDR_DEFINED)
+    {
+        setenv_route_addr(es, "net_gateway", rl->rgi.gateway.addr, -1);
+#if defined(ENABLE_DEBUG) && !defined(ENABLE_SMALL)
+        print_default_gateway(D_ROUTE, &rl->rgi, NULL);
+#endif
+    }
+    else
+    {
+        dmsg(D_ROUTE, "ROUTE: default_gateway=UNDEF");
+    }
+
+    if (rl->spec.flags & RTSA_REMOTE_HOST)
+    {
+        rl->spec.remote_host_local = test_local_addr(remote_host, &rl->rgi);
+    }
+
+    if (is_route_parm_defined(remote_endpoint))
+    {
+        bool defined = false;
+        rl->spec.remote_endpoint = getaddr(
+            GETADDR_RESOLVE
+            | GETADDR_HOST_ORDER
+            | GETADDR_WARN_ON_SIGNAL,
+            remote_endpoint,
+            0,
+            &defined,
+            NULL);
+
+        if (defined)
+        {
+            setenv_route_addr(es, "vpn_gateway", rl->spec.remote_endpoint, -1);
+            rl->spec.flags |= RTSA_REMOTE_ENDPOINT;
+        }
+        else
+        {
+            msg(M_WARN, PACKAGE_NAME " ROUTE: failed to parse/resolve default gateway: %s",
+                remote_endpoint);
+            ret = false;
+        }
+    }
+
+    if (rl->flags & RG_ENABLE)
+    {
+        add_block_local(rl);
+        get_bypass_addresses(&rl->spec.bypass, rl->flags);
+#ifdef ENABLE_DEBUG
+        print_bypass_addresses(&rl->spec.bypass);
+#endif
+    }
+
+    /* parse the routes from opt to rl */
+    {
+        struct route_option *ro;
+        for (ro = opt->routes; ro; ro = ro->next)
+        {
+            struct addrinfo *netlist = NULL;
+            struct route_ipv4 r;
+
+            if (!init_route(&r, &netlist, ro, rl))
+            {
+                ret = false;
+            }
+            else
+            {
+                struct addrinfo *curele;
+                for (curele = netlist; curele; curele = curele->ai_next)
+                {
+                    struct route_ipv4 *new;
+                    ALLOC_OBJ_GC(new, struct route_ipv4, &rl->gc);
+                    *new = r;
+                    new->network = ntohl(((struct sockaddr_in *)curele->ai_addr)->sin_addr.s_addr);
+                    new->next = rl->routes;
+                    rl->routes = new;
+                }
+            }
+            if (netlist)
+            {
+                gc_addspecial(netlist, &gc_freeaddrinfo_callback, &gc);
+            }
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+/* check whether an IPv6 host address is covered by a given route_ipv6
+ * (not the most beautiful implementation in the world, but portable and
+ * "good enough")
+ */
+static bool
+route_ipv6_match_host( const struct route_ipv6 *r6,
+                       const struct in6_addr *host )
+{
+    unsigned int bits = r6->netbits;
+    int i;
+    unsigned int mask;
+
+    if (bits>128)
+    {
+        return false;
+    }
+
+    for (i = 0; bits >= 8; i++, bits -= 8)
+    {
+        if (r6->network.s6_addr[i] != host->s6_addr[i])
+        {
+            return false;
+        }
+    }
+
+    if (bits == 0)
+    {
+        return true;
+    }
+
+    mask = 0xff << (8-bits);
+
+    if ( (r6->network.s6_addr[i] & mask) == (host->s6_addr[i] & mask ))
+    {
+        return true;
+    }
+
+    return false;
+}
+
+bool
+init_route_ipv6_list(struct route_ipv6_list *rl6,
+                     const struct route_ipv6_option_list *opt6,
+                     const char *remote_endpoint,
+                     int default_metric,
+                     const struct in6_addr *remote_host_ipv6,
+                     struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = true;
+    bool need_remote_ipv6_route;
+
+    clear_route_ipv6_list(rl6);
+
+    rl6->flags = opt6->flags;
+
+    if (remote_host_ipv6)
+    {
+        rl6->remote_host_ipv6 = *remote_host_ipv6;
+        rl6->spec_flags |= RTSA_REMOTE_HOST;
+    }
+
+    if (default_metric >= 0)
+    {
+        rl6->default_metric = default_metric;
+        rl6->spec_flags |= RTSA_DEFAULT_METRIC;
+    }
+
+    msg(D_ROUTE, "GDG6: remote_host_ipv6=%s",
+        remote_host_ipv6 ?  print_in6_addr(*remote_host_ipv6, 0, &gc) : "n/a" );
+
+    get_default_gateway_ipv6(&rl6->rgi6, remote_host_ipv6);
+    if (rl6->rgi6.flags & RGI_ADDR_DEFINED)
+    {
+        setenv_str(es, "net_gateway_ipv6", print_in6_addr(rl6->rgi6.gateway.addr_ipv6, 0, &gc));
+#if defined(ENABLE_DEBUG) && !defined(ENABLE_SMALL)
+        print_default_gateway(D_ROUTE, NULL, &rl6->rgi6);
+#endif
+    }
+    else
+    {
+        dmsg(D_ROUTE, "ROUTE6: default_gateway=UNDEF");
+    }
+
+    if (is_route_parm_defined( remote_endpoint ))
+    {
+        if (inet_pton( AF_INET6, remote_endpoint,
+                       &rl6->remote_endpoint_ipv6) == 1)
+        {
+            rl6->spec_flags |= RTSA_REMOTE_ENDPOINT;
+        }
+        else
+        {
+            msg(M_WARN, PACKAGE_NAME " ROUTE: failed to parse/resolve VPN endpoint: %s", remote_endpoint);
+            ret = false;
+        }
+    }
+
+    /* parse the routes from opt6 to rl6
+     * discovering potential overlaps with remote_host_ipv6 in the process
+     */
+    need_remote_ipv6_route = false;
+
+    {
+        struct route_ipv6_option *ro6;
+        for (ro6 = opt6->routes_ipv6; ro6; ro6 = ro6->next)
+        {
+            struct route_ipv6 *r6;
+            ALLOC_OBJ_GC(r6, struct route_ipv6, &rl6->gc);
+            if (!init_route_ipv6(r6, ro6, rl6))
+            {
+                ret = false;
+            }
+            else
+            {
+                r6->next = rl6->routes_ipv6;
+                rl6->routes_ipv6 = r6;
+
+#ifndef TARGET_ANDROID
+                /* On Android the VPNService protect function call will take of
+                 * avoiding routing loops, so ignore this part and let
+                 * need_remote_ipv6_route always evaluate to false
+                 */
+                if (remote_host_ipv6
+                    && route_ipv6_match_host( r6, remote_host_ipv6 ) )
+                {
+                    need_remote_ipv6_route = true;
+                    msg(D_ROUTE, "ROUTE6: %s/%d overlaps IPv6 remote %s, adding host route to VPN endpoint",
+                        print_in6_addr(r6->network, 0, &gc), r6->netbits,
+                        print_in6_addr(*remote_host_ipv6, 0, &gc));
+                }
+#endif
+            }
+        }
+    }
+
+    /* add VPN server host route if needed */
+    if (need_remote_ipv6_route)
+    {
+        if ( (rl6->rgi6.flags & (RGI_ADDR_DEFINED|RGI_IFACE_DEFINED) ) ==
+             (RGI_ADDR_DEFINED|RGI_IFACE_DEFINED) )
+        {
+            struct route_ipv6 *r6;
+            ALLOC_OBJ_CLEAR_GC(r6, struct route_ipv6, &rl6->gc);
+
+            r6->network = *remote_host_ipv6;
+            r6->netbits = 128;
+            if (!(rl6->rgi6.flags & RGI_ON_LINK) )
+            {
+                r6->gateway = rl6->rgi6.gateway.addr_ipv6;
+            }
+            r6->metric = 1;
+#ifdef _WIN32
+            r6->adapter_index = rl6->rgi6.adapter_index;
+#else
+            r6->iface = rl6->rgi6.iface;
+#endif
+            r6->flags = RT_DEFINED | RT_METRIC_DEFINED;
+
+            r6->next = rl6->routes_ipv6;
+            rl6->routes_ipv6 = r6;
+        }
+        else
+        {
+            msg(M_WARN, "ROUTE6: IPv6 route overlaps with IPv6 remote address, but could not determine IPv6 gateway address + interface, expect failure\n" );
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+static void
+add_route3(in_addr_t network,
+           in_addr_t netmask,
+           in_addr_t gateway,
+           const struct tuntap *tt,
+           unsigned int flags,
+           const struct route_gateway_info *rgi,
+           const struct env_set *es)
+{
+    struct route_ipv4 r;
+    CLEAR(r);
+    r.flags = RT_DEFINED;
+    r.network = network;
+    r.netmask = netmask;
+    r.gateway = gateway;
+    add_route(&r, tt, flags, rgi, es);
+}
+
+static void
+del_route3(in_addr_t network,
+           in_addr_t netmask,
+           in_addr_t gateway,
+           const struct tuntap *tt,
+           unsigned int flags,
+           const struct route_gateway_info *rgi,
+           const struct env_set *es)
+{
+    struct route_ipv4 r;
+    CLEAR(r);
+    r.flags = RT_DEFINED|RT_ADDED;
+    r.network = network;
+    r.netmask = netmask;
+    r.gateway = gateway;
+    delete_route(&r, tt, flags, rgi, es);
+}
+
+static void
+add_bypass_routes(struct route_bypass *rb,
+                  in_addr_t gateway,
+                  const struct tuntap *tt,
+                  unsigned int flags,
+                  const struct route_gateway_info *rgi,
+                  const struct env_set *es)
+{
+    int i;
+    for (i = 0; i < rb->n_bypass; ++i)
+    {
+        if (rb->bypass[i])
+        {
+            add_route3(rb->bypass[i],
+                       IPV4_NETMASK_HOST,
+                       gateway,
+                       tt,
+                       flags | ROUTE_REF_GW,
+                       rgi,
+                       es);
+        }
+    }
+}
+
+static void
+del_bypass_routes(struct route_bypass *rb,
+                  in_addr_t gateway,
+                  const struct tuntap *tt,
+                  unsigned int flags,
+                  const struct route_gateway_info *rgi,
+                  const struct env_set *es)
+{
+    int i;
+    for (i = 0; i < rb->n_bypass; ++i)
+    {
+        if (rb->bypass[i])
+        {
+            del_route3(rb->bypass[i],
+                       IPV4_NETMASK_HOST,
+                       gateway,
+                       tt,
+                       flags | ROUTE_REF_GW,
+                       rgi,
+                       es);
+        }
+    }
+}
+
+static void
+redirect_default_route_to_vpn(struct route_list *rl, const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    const char err[] = "NOTE: unable to redirect default gateway --";
+
+    if (rl && rl->flags & RG_ENABLE)
+    {
+        bool local = rl->flags & RG_LOCAL;
+
+        if (!(rl->spec.flags & RTSA_REMOTE_ENDPOINT) && (rl->flags & RG_REROUTE_GW))
+        {
+            msg(M_WARN, "%s VPN gateway parameter (--route-gateway or --ifconfig) is missing", err);
+        }
+        /*
+         * check if a default route is defined, unless:
+         * - we are connecting to a remote host in our network
+         * - we are connecting to a non-IPv4 remote host (i.e. we use IPv6)
+         */
+        else if (!(rl->rgi.flags & RGI_ADDR_DEFINED) && !local
+                 && (rl->spec.remote_host != IPV4_INVALID_ADDR))
+        {
+            msg(M_WARN, "%s Cannot read current default gateway from system", err);
+        }
+        else if (!(rl->spec.flags & RTSA_REMOTE_HOST))
+        {
+            msg(M_WARN, "%s Cannot obtain current remote host address", err);
+        }
+        else
+        {
+#ifndef TARGET_ANDROID
+            if (rl->flags & RG_AUTO_LOCAL)
+            {
+                const int tla = rl->spec.remote_host_local;
+                if (tla == TLA_NONLOCAL)
+                {
+                    dmsg(D_ROUTE, "ROUTE remote_host is NOT LOCAL");
+                    local = false;
+                }
+                else if (tla == TLA_LOCAL)
+                {
+                    dmsg(D_ROUTE, "ROUTE remote_host is LOCAL");
+                    local = true;
+                }
+            }
+            if (!local)
+            {
+                /* route remote host to original default gateway */
+                /* if remote_host is not ipv4 (ie: ipv6), just skip
+                 * adding this special /32 route */
+                if (rl->spec.remote_host != IPV4_INVALID_ADDR)
+                {
+                    add_route3(rl->spec.remote_host,
+                               IPV4_NETMASK_HOST,
+                               rl->rgi.gateway.addr,
+                               tt,
+                               flags | ROUTE_REF_GW,
+                               &rl->rgi,
+                               es);
+                    rl->iflags |= RL_DID_LOCAL;
+                }
+                else
+                {
+                    dmsg(D_ROUTE, "ROUTE remote_host protocol differs from tunneled");
+                }
+            }
+#endif /* ifndef TARGET_ANDROID */
+
+            /* route DHCP/DNS server traffic through original default gateway */
+            add_bypass_routes(&rl->spec.bypass, rl->rgi.gateway.addr, tt, flags, &rl->rgi, es);
+
+            if (rl->flags & RG_REROUTE_GW)
+            {
+                if (rl->flags & RG_DEF1)
+                {
+                    /* add new default route (1st component) */
+                    add_route3(0x00000000,
+                               0x80000000,
+                               rl->spec.remote_endpoint,
+                               tt,
+                               flags,
+                               &rl->rgi,
+                               es);
+
+                    /* add new default route (2nd component) */
+                    add_route3(0x80000000,
+                               0x80000000,
+                               rl->spec.remote_endpoint,
+                               tt,
+                               flags,
+                               &rl->rgi,
+                               es);
+                }
+                else
+                {
+                    /* don't try to remove the def route if it does not exist */
+                    if (rl->rgi.flags & RGI_ADDR_DEFINED)
+                    {
+                        /* delete default route */
+                        del_route3(0, 0, rl->rgi.gateway.addr, tt,
+                                   flags | ROUTE_REF_GW, &rl->rgi, es);
+                    }
+
+                    /* add new default route */
+                    add_route3(0,
+                               0,
+                               rl->spec.remote_endpoint,
+                               tt,
+                               flags,
+                               &rl->rgi,
+                               es);
+                }
+            }
+
+            /* set a flag so we can undo later */
+            rl->iflags |= RL_DID_REDIRECT_DEFAULT_GATEWAY;
+        }
+    }
+}
+
+static void
+undo_redirect_default_route_to_vpn(struct route_list *rl, const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    if (rl && rl->iflags & RL_DID_REDIRECT_DEFAULT_GATEWAY)
+    {
+        /* delete remote host route */
+        if (rl->iflags & RL_DID_LOCAL)
+        {
+            del_route3(rl->spec.remote_host,
+                       IPV4_NETMASK_HOST,
+                       rl->rgi.gateway.addr,
+                       tt,
+                       flags | ROUTE_REF_GW,
+                       &rl->rgi,
+                       es);
+            rl->iflags &= ~RL_DID_LOCAL;
+        }
+
+        /* delete special DHCP/DNS bypass route */
+        del_bypass_routes(&rl->spec.bypass, rl->rgi.gateway.addr, tt, flags, &rl->rgi, es);
+
+        if (rl->flags & RG_REROUTE_GW)
+        {
+            if (rl->flags & RG_DEF1)
+            {
+                /* delete default route (1st component) */
+                del_route3(0x00000000,
+                           0x80000000,
+                           rl->spec.remote_endpoint,
+                           tt,
+                           flags,
+                           &rl->rgi,
+                           es);
+
+                /* delete default route (2nd component) */
+                del_route3(0x80000000,
+                           0x80000000,
+                           rl->spec.remote_endpoint,
+                           tt,
+                           flags,
+                           &rl->rgi,
+                           es);
+            }
+            else
+            {
+                /* delete default route */
+                del_route3(0,
+                           0,
+                           rl->spec.remote_endpoint,
+                           tt,
+                           flags,
+                           &rl->rgi,
+                           es);
+                /* restore original default route if there was any */
+                if (rl->rgi.flags & RGI_ADDR_DEFINED)
+                {
+                    add_route3(0, 0, rl->rgi.gateway.addr, tt,
+                               flags | ROUTE_REF_GW, &rl->rgi, es);
+                }
+            }
+        }
+
+        rl->iflags &= ~RL_DID_REDIRECT_DEFAULT_GATEWAY;
+    }
+}
+
+void
+add_routes(struct route_list *rl, struct route_ipv6_list *rl6, const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    redirect_default_route_to_vpn(rl, tt, flags, es);
+    if (rl && !(rl->iflags & RL_ROUTES_ADDED) )
+    {
+        struct route_ipv4 *r;
+
+#ifdef ENABLE_MANAGEMENT
+        if (management && rl->routes)
+        {
+            management_set_state(management,
+                                 OPENVPN_STATE_ADD_ROUTES,
+                                 NULL,
+                                 NULL,
+                                 NULL,
+                                 NULL,
+                                 NULL);
+        }
+#endif
+
+        for (r = rl->routes; r; r = r->next)
+        {
+            check_subnet_conflict(r->network, r->netmask, "route");
+            if (flags & ROUTE_DELETE_FIRST)
+            {
+                delete_route(r, tt, flags, &rl->rgi, es);
+            }
+            add_route(r, tt, flags, &rl->rgi, es);
+        }
+        rl->iflags |= RL_ROUTES_ADDED;
+    }
+    if (rl6 && !(rl6->iflags & RL_ROUTES_ADDED) )
+    {
+        struct route_ipv6 *r;
+
+        if (!tt->did_ifconfig_ipv6_setup)
+        {
+            msg(M_INFO, "WARNING: OpenVPN was configured to add an IPv6 "
+                "route over %s. However, no IPv6 has been configured for "
+                "this interface, therefore the route installation may "
+                "fail or may not work as expected.", tt->actual_name);
+        }
+
+        for (r = rl6->routes_ipv6; r; r = r->next)
+        {
+            if (flags & ROUTE_DELETE_FIRST)
+            {
+                delete_route_ipv6(r, tt, flags, es);
+            }
+            add_route_ipv6(r, tt, flags, es);
+        }
+        rl6->iflags |= RL_ROUTES_ADDED;
+    }
+}
+
+void
+delete_routes(struct route_list *rl, struct route_ipv6_list *rl6,
+              const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    if (rl && rl->iflags & RL_ROUTES_ADDED)
+    {
+        struct route_ipv4 *r;
+        for (r = rl->routes; r; r = r->next)
+        {
+            delete_route(r, tt, flags, &rl->rgi, es);
+        }
+        rl->iflags &= ~RL_ROUTES_ADDED;
+    }
+
+    undo_redirect_default_route_to_vpn(rl, tt, flags, es);
+
+    if (rl)
+    {
+        clear_route_list(rl);
+    }
+
+    if (rl6 && (rl6->iflags & RL_ROUTES_ADDED) )
+    {
+        struct route_ipv6 *r6;
+        for (r6 = rl6->routes_ipv6; r6; r6 = r6->next)
+        {
+            delete_route_ipv6(r6, tt, flags, es);
+        }
+        rl6->iflags &= ~RL_ROUTES_ADDED;
+    }
+
+    if (rl6)
+    {
+        clear_route_ipv6_list(rl6);
+    }
+}
+
+#ifndef ENABLE_SMALL
+
+static const char *
+show_opt(const char *option)
+{
+    if (!option)
+    {
+        return "default (not set)";
+    }
+    else
+    {
+        return option;
+    }
+}
+
+static void
+print_route_option(const struct route_option *ro, int level)
+{
+    msg(level, "  route %s/%s/%s/%s",
+        show_opt(ro->network),
+        show_opt(ro->netmask),
+        show_opt(ro->gateway),
+        show_opt(ro->metric));
+}
+
+void
+print_route_options(const struct route_option_list *rol,
+                    int level)
+{
+    struct route_option *ro;
+    if (rol->flags & RG_ENABLE)
+    {
+        msg(level, "  [redirect_default_gateway local=%d]",
+            (rol->flags & RG_LOCAL) != 0);
+    }
+    for (ro = rol->routes; ro; ro = ro->next)
+    {
+        print_route_option(ro, level);
+    }
+}
+
+void
+print_default_gateway(const int msglevel,
+                      const struct route_gateway_info *rgi,
+                      const struct route_ipv6_gateway_info *rgi6)
+{
+    struct gc_arena gc = gc_new();
+    if (rgi && (rgi->flags & RGI_ADDR_DEFINED))
+    {
+        struct buffer out = alloc_buf_gc(256, &gc);
+        buf_printf(&out, "ROUTE_GATEWAY");
+        if (rgi->flags & RGI_ON_LINK)
+        {
+            buf_printf(&out, " ON_LINK");
+        }
+        else
+        {
+            buf_printf(&out, " %s", print_in_addr_t(rgi->gateway.addr, 0, &gc));
+        }
+        if (rgi->flags & RGI_NETMASK_DEFINED)
+        {
+            buf_printf(&out, "/%s", print_in_addr_t(rgi->gateway.netmask, 0, &gc));
+        }
+#ifdef _WIN32
+        if (rgi->flags & RGI_IFACE_DEFINED)
+        {
+            buf_printf(&out, " I=%u", (unsigned int)rgi->adapter_index);
+        }
+#else
+        if (rgi->flags & RGI_IFACE_DEFINED)
+        {
+            buf_printf(&out, " IFACE=%s", rgi->iface);
+        }
+#endif
+        if (rgi->flags & RGI_HWADDR_DEFINED)
+        {
+            buf_printf(&out, " HWADDR=%s", format_hex_ex(rgi->hwaddr, 6, 0, 1, ":", &gc));
+        }
+        msg(msglevel, "%s", BSTR(&out));
+    }
+
+    if (rgi6 && (rgi6->flags & RGI_ADDR_DEFINED))
+    {
+        struct buffer out = alloc_buf_gc(256, &gc);
+        buf_printf(&out, "ROUTE6_GATEWAY");
+        buf_printf(&out, " %s", print_in6_addr(rgi6->gateway.addr_ipv6, 0, &gc));
+        if (rgi6->flags & RGI_ON_LINK)
+        {
+            buf_printf(&out, " ON_LINK");
+        }
+        if (rgi6->flags & RGI_NETMASK_DEFINED)
+        {
+            buf_printf(&out, "/%d", rgi6->gateway.netbits_ipv6);
+        }
+#ifdef _WIN32
+        if (rgi6->flags & RGI_IFACE_DEFINED)
+        {
+            buf_printf(&out, " I=%u", (unsigned int)rgi6->adapter_index);
+        }
+#else
+        if (rgi6->flags & RGI_IFACE_DEFINED)
+        {
+            buf_printf(&out, " IFACE=%s", rgi6->iface);
+        }
+#endif
+        if (rgi6->flags & RGI_HWADDR_DEFINED)
+        {
+            buf_printf(&out, " HWADDR=%s", format_hex_ex(rgi6->hwaddr, 6, 0, 1, ":", &gc));
+        }
+        msg(msglevel, "%s", BSTR(&out));
+    }
+    gc_free(&gc);
+}
+
+#endif /* ifndef ENABLE_SMALL */
+
+static void
+print_route(const struct route_ipv4 *r, int level)
+{
+    struct gc_arena gc = gc_new();
+    if (r->flags & RT_DEFINED)
+    {
+        msg(level, "%s", route_string(r, &gc));
+    }
+    gc_free(&gc);
+}
+
+void
+print_routes(const struct route_list *rl, int level)
+{
+    struct route_ipv4 *r;
+    for (r = rl->routes; r; r = r->next)
+    {
+        print_route(r, level);
+    }
+}
+
+static void
+setenv_route(struct env_set *es, const struct route_ipv4 *r, int i)
+{
+    struct gc_arena gc = gc_new();
+    if (r->flags & RT_DEFINED)
+    {
+        setenv_route_addr(es, "network", r->network, i);
+        setenv_route_addr(es, "netmask", r->netmask, i);
+        setenv_route_addr(es, "gateway", r->gateway, i);
+
+        if (r->flags & RT_METRIC_DEFINED)
+        {
+            struct buffer name = alloc_buf_gc(256, &gc);
+            buf_printf(&name, "route_metric_%d", i);
+            setenv_int(es, BSTR(&name), r->metric);
+        }
+    }
+    gc_free(&gc);
+}
+
+void
+setenv_routes(struct env_set *es, const struct route_list *rl)
+{
+    int i = 1;
+    struct route_ipv4 *r;
+    for (r = rl->routes; r; r = r->next)
+    {
+        setenv_route(es, r, i++);
+    }
+}
+
+static void
+setenv_route_ipv6(struct env_set *es, const struct route_ipv6 *r6, int i)
+{
+    struct gc_arena gc = gc_new();
+    if (r6->flags & RT_DEFINED)
+    {
+        struct buffer name1 = alloc_buf_gc( 256, &gc );
+        struct buffer val = alloc_buf_gc( 256, &gc );
+        struct buffer name2 = alloc_buf_gc( 256, &gc );
+
+        buf_printf( &name1, "route_ipv6_network_%d", i );
+        buf_printf( &val, "%s/%d", print_in6_addr( r6->network, 0, &gc ),
+                    r6->netbits );
+        setenv_str( es, BSTR(&name1), BSTR(&val) );
+
+        buf_printf( &name2, "route_ipv6_gateway_%d", i );
+        setenv_str( es, BSTR(&name2), print_in6_addr( r6->gateway, 0, &gc ));
+    }
+    gc_free(&gc);
+}
+void
+setenv_routes_ipv6(struct env_set *es, const struct route_ipv6_list *rl6)
+{
+    int i = 1;
+    struct route_ipv6 *r6;
+    for (r6 = rl6->routes_ipv6; r6; r6 = r6->next)
+    {
+        setenv_route_ipv6(es, r6, i++);
+    }
+}
+
+/*
+ * local_route() determines whether the gateway of a provided host
+ * route is on the same interface that owns the default gateway.
+ * It uses the data structure
+ * returned by get_default_gateway() (struct route_gateway_info)
+ * to determine this.  If the route is local, LR_MATCH is returned.
+ * When adding routes into the kernel, if LR_MATCH is defined for
+ * a given route, the route should explicitly reference the default
+ * gateway interface as the route destination.  For example, here
+ * is an example on Linux that uses LR_MATCH:
+ *
+ *   route add -net 10.10.0.1 netmask 255.255.255.255 dev eth0
+ *
+ * This capability is needed by the "default-gateway block-local"
+ * directive, to allow client access to the local subnet to be
+ * blocked but still allow access to the local default gateway.
+ */
+
+/* local_route() return values */
+#define LR_NOMATCH 0 /* route is not local */
+#define LR_MATCH   1 /* route is local */
+#define LR_ERROR   2 /* caller should abort adding route */
+
+static int
+local_route(in_addr_t network,
+            in_addr_t netmask,
+            in_addr_t gateway,
+            const struct route_gateway_info *rgi)
+{
+    /* set LR_MATCH on local host routes */
+    const int rgi_needed = (RGI_ADDR_DEFINED|RGI_NETMASK_DEFINED|RGI_IFACE_DEFINED);
+    if (rgi
+        && (rgi->flags & rgi_needed) == rgi_needed
+        && gateway == rgi->gateway.addr
+        && netmask == 0xFFFFFFFF)
+    {
+        if (((network ^  rgi->gateway.addr) & rgi->gateway.netmask) == 0)
+        {
+            return LR_MATCH;
+        }
+        else
+        {
+            /* examine additional subnets on gateway interface */
+            size_t i;
+            for (i = 0; i < rgi->n_addrs; ++i)
+            {
+                const struct route_gateway_address *gwa = &rgi->addrs[i];
+                if (((network ^ gwa->addr) & gwa->netmask) == 0)
+                {
+                    return LR_MATCH;
+                }
+            }
+        }
+    }
+    return LR_NOMATCH;
+}
+
+/* Return true if the "on-link" form of the route should be used.  This is when the gateway for a
+ * a route is specified as an interface rather than an address. */
+static inline bool
+is_on_link(const int is_local_route, const unsigned int flags, const struct route_gateway_info *rgi)
+{
+    return rgi && (is_local_route == LR_MATCH || ((flags & ROUTE_REF_GW) && (rgi->flags & RGI_ON_LINK)));
+}
+
+void
+add_route(struct route_ipv4 *r,
+          const struct tuntap *tt,
+          unsigned int flags,
+          const struct route_gateway_info *rgi,  /* may be NULL */
+          const struct env_set *es)
+{
+    struct gc_arena gc;
+    struct argv argv = argv_new();
+    const char *network;
+#if !defined(ENABLE_IPROUTE) && !defined(TARGET_AIX)
+    const char *netmask;
+#endif
+    const char *gateway;
+    bool status = false;
+    int is_local_route;
+
+    if (!(r->flags & RT_DEFINED))
+    {
+        return;
+    }
+
+    gc_init(&gc);
+
+    network = print_in_addr_t(r->network, 0, &gc);
+#if !defined(ENABLE_IPROUTE) && !defined(TARGET_AIX)
+    netmask = print_in_addr_t(r->netmask, 0, &gc);
+#endif
+    gateway = print_in_addr_t(r->gateway, 0, &gc);
+
+    is_local_route = local_route(r->network, r->netmask, r->gateway, rgi);
+    if (is_local_route == LR_ERROR)
+    {
+        goto done;
+    }
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+    argv_printf(&argv, "%s route add %s/%d",
+                iproute_path,
+                network,
+                netmask_to_netbits2(r->netmask));
+
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "metric %d", r->metric);
+    }
+
+    if (is_on_link(is_local_route, flags, rgi))
+    {
+        argv_printf_cat(&argv, "dev %s", rgi->iface);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "via %s", gateway);
+    }
+#else  /* ifdef ENABLE_IPROUTE */
+    argv_printf(&argv, "%s add -net %s netmask %s",
+                ROUTE_PATH,
+                network,
+                netmask);
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "metric %d", r->metric);
+    }
+    if (is_on_link(is_local_route, flags, rgi))
+    {
+        argv_printf_cat(&argv, "dev %s", rgi->iface);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "gw %s", gateway);
+    }
+
+#endif  /*ENABLE_IPROUTE*/
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: Linux route add command failed");
+
+#elif defined (TARGET_ANDROID)
+    struct buffer out = alloc_buf_gc(128, &gc);
+
+    if (rgi)
+    {
+        buf_printf(&out, "%s %s %s dev %s", network, netmask, gateway, rgi->iface);
+    }
+    else
+    {
+        buf_printf(&out, "%s %s %s", network, netmask, gateway);
+    }
+    management_android_control(management, "ROUTE", buf_bptr(&out));
+
+#elif defined (_WIN32)
+    {
+        DWORD ai = TUN_ADAPTER_INDEX_INVALID;
+        argv_printf(&argv, "%s%sc ADD %s MASK %s %s",
+                    get_win_sys_path(),
+                    WIN_ROUTE_PATH_SUFFIX,
+                    network,
+                    netmask,
+                    gateway);
+        if (r->flags & RT_METRIC_DEFINED)
+        {
+            argv_printf_cat(&argv, "METRIC %d", r->metric);
+        }
+        if (is_on_link(is_local_route, flags, rgi))
+        {
+            ai = rgi->adapter_index;
+            argv_printf_cat(&argv, "IF %u", (unsigned int)ai);
+        }
+
+        argv_msg(D_ROUTE, &argv);
+
+        if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_SERVICE)
+        {
+            status = add_route_service(r, tt);
+            msg(D_ROUTE, "Route addition via service %s", status ? "succeeded" : "failed");
+        }
+        else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_IPAPI)
+        {
+            status = add_route_ipapi(r, tt, ai);
+            msg(D_ROUTE, "Route addition via IPAPI %s", status ? "succeeded" : "failed");
+        }
+        else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_EXE)
+        {
+            netcmd_semaphore_lock();
+            status = openvpn_execve_check(&argv, es, 0, "ERROR: Windows route add command failed");
+            netcmd_semaphore_release();
+        }
+        else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_ADAPTIVE)
+        {
+            status = add_route_ipapi(r, tt, ai);
+            msg(D_ROUTE, "Route addition via IPAPI %s [adaptive]", status ? "succeeded" : "failed");
+            if (!status)
+            {
+                msg(D_ROUTE, "Route addition fallback to route.exe");
+                netcmd_semaphore_lock();
+                status = openvpn_execve_check(&argv, es, 0, "ERROR: Windows route add command failed [adaptive]");
+                netcmd_semaphore_release();
+            }
+        }
+        else
+        {
+            ASSERT(0);
+        }
+    }
+
+#elif defined (TARGET_SOLARIS)
+
+    /* example: route add 192.0.2.32 -netmask 255.255.255.224 somegateway */
+
+    argv_printf(&argv, "%s add",
+                ROUTE_PATH);
+
+    argv_printf_cat(&argv, "%s -netmask %s %s",
+                    network,
+                    netmask,
+                    gateway);
+
+    /* Solaris can only distinguish between "metric 0" == "on-link on the
+     * interface where the IP address given is configured" and "metric > 0"
+     * == "use gateway specified" (no finer-grained route metrics available)
+     *
+     * More recent versions of Solaris can also do "-interface", but that
+     * would break backwards compatibility with older versions for no gain.
+     */
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "%d", r->metric);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: Solaris route add command failed");
+
+#elif defined(TARGET_FREEBSD)
+
+    argv_printf(&argv, "%s add",
+                ROUTE_PATH);
+
+#if 0
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "-rtt %d", r->metric);
+    }
+#endif
+
+    argv_printf_cat(&argv, "-net %s %s %s",
+                    network,
+                    gateway,
+                    netmask);
+
+    /* FIXME -- add on-link support for FreeBSD */
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: FreeBSD route add command failed");
+
+#elif defined(TARGET_DRAGONFLY)
+
+    argv_printf(&argv, "%s add",
+                ROUTE_PATH);
+
+#if 0
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "-rtt %d", r->metric);
+    }
+#endif
+
+    argv_printf_cat(&argv, "-net %s %s %s",
+                    network,
+                    gateway,
+                    netmask);
+
+    /* FIXME -- add on-link support for Dragonfly */
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: DragonFly route add command failed");
+
+#elif defined(TARGET_DARWIN)
+
+    argv_printf(&argv, "%s add",
+                ROUTE_PATH);
+
+#if 0
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "-rtt %d", r->metric);
+    }
+#endif
+
+    if (is_on_link(is_local_route, flags, rgi))
+    {
+        /* Mac OS X route syntax for ON_LINK:
+         * route add -cloning -net 10.10.0.1 -netmask 255.255.255.255 -interface en0 */
+        argv_printf_cat(&argv, "-cloning -net %s -netmask %s -interface %s",
+                        network,
+                        netmask,
+                        rgi->iface);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "-net %s %s %s",
+                        network,
+                        gateway,
+                        netmask);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: OS X route add command failed");
+
+#elif defined(TARGET_OPENBSD) || defined(TARGET_NETBSD)
+
+    argv_printf(&argv, "%s add",
+                ROUTE_PATH);
+
+#if 0
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "-rtt %d", r->metric);
+    }
+#endif
+
+    argv_printf_cat(&argv, "-net %s %s -netmask %s",
+                    network,
+                    gateway,
+                    netmask);
+
+    /* FIXME -- add on-link support for OpenBSD/NetBSD */
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: OpenBSD/NetBSD route add command failed");
+
+#elif defined(TARGET_AIX)
+
+    {
+        int netbits = netmask_to_netbits2(r->netmask);
+        argv_printf(&argv, "%s add -net %s/%d %s",
+                    ROUTE_PATH,
+                    network, netbits, gateway);
+        argv_msg(D_ROUTE, &argv);
+        status = openvpn_execve_check(&argv, es, 0, "ERROR: AIX route add command failed");
+    }
+
+#else  /* if defined(TARGET_LINUX) */
+    msg(M_FATAL, "Sorry, but I don't know how to do 'route' commands on this operating system.  Try putting your routes in a --route-up script");
+#endif /* if defined(TARGET_LINUX) */
+
+done:
+    if (status)
+    {
+        r->flags |= RT_ADDED;
+    }
+    else
+    {
+        r->flags &= ~RT_ADDED;
+    }
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+
+void
+route_ipv6_clear_host_bits( struct route_ipv6 *r6 )
+{
+    /* clear host bit parts of route
+     * (needed if routes are specified improperly, or if we need to
+     * explicitely setup/clear the "connected" network routes on some OSes)
+     */
+    int byte = 15;
+    int bits_to_clear = 128 - r6->netbits;
+
+    while (byte >= 0 && bits_to_clear > 0)
+    {
+        if (bits_to_clear >= 8)
+        {
+            r6->network.s6_addr[byte--] = 0; bits_to_clear -= 8;
+        }
+        else
+        {
+            r6->network.s6_addr[byte--] &= (0xff << bits_to_clear); bits_to_clear = 0;
+        }
+    }
+}
+
+void
+add_route_ipv6(struct route_ipv6 *r6, const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    struct gc_arena gc;
+    struct argv argv = argv_new();
+
+    const char *network;
+    const char *gateway;
+    bool status = false;
+    const char *device = tt->actual_name;
+
+    bool gateway_needed = false;
+
+    if (!(r6->flags & RT_DEFINED) )
+    {
+        return;
+    }
+
+#ifndef _WIN32
+    if (r6->iface != NULL)              /* vpn server special route */
+    {
+        device = r6->iface;
+        if (!IN6_IS_ADDR_UNSPECIFIED(&r6->gateway) )
+        {
+            gateway_needed = true;
+        }
+    }
+#endif
+
+    gc_init(&gc);
+
+    route_ipv6_clear_host_bits(r6);
+
+    network = print_in6_addr( r6->network, 0, &gc);
+    gateway = print_in6_addr( r6->gateway, 0, &gc);
+
+#if defined(TARGET_DARWIN)    \
+    || defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)    \
+    || defined(TARGET_OPENBSD) || defined(TARGET_NETBSD)
+
+    /* the BSD platforms cannot specify gateway and interface independently,
+     * but for link-local destinations, we MUST specify the interface, so
+     * we build a combined "$gateway%$interface" gateway string
+     */
+    if (r6->iface != NULL && gateway_needed
+        && IN6_IS_ADDR_LINKLOCAL(&r6->gateway) )        /* fe80::...%intf */
+    {
+        int len = strlen(gateway) + 1 + strlen(r6->iface)+1;
+        char *tmp = gc_malloc( len, true, &gc );
+        snprintf( tmp, len, "%s%%%s", gateway, r6->iface );
+        gateway = tmp;
+    }
+#endif
+
+    msg( M_INFO, "add_route_ipv6(%s/%d -> %s metric %d) dev %s",
+         network, r6->netbits, gateway, r6->metric, device );
+
+    /*
+     * Filter out routes which are essentially no-ops
+     * (not currently done for IPv6)
+     */
+
+    /* On "tun" interface, we never set a gateway if the operating system
+     * can do "route to interface" - it does not add value, as the target
+     * dev already fully qualifies the route destination on point-to-point
+     * interfaces.   OTOH, on "tap" interface, we must always set the
+     * gateway unless the route is to be an on-link network
+     */
+    if (tt->type == DEV_TYPE_TAP
+        && !( (r6->flags & RT_METRIC_DEFINED) && r6->metric == 0 ) )
+    {
+        gateway_needed = true;
+    }
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+    argv_printf(&argv, "%s -6 route add %s/%d dev %s",
+                iproute_path,
+                network,
+                r6->netbits,
+                device);
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "via %s", gateway);
+    }
+    if ( (r6->flags & RT_METRIC_DEFINED) && r6->metric > 0)
+    {
+        argv_printf_cat(&argv, " metric %d", r6->metric);
+    }
+
+#else  /* ifdef ENABLE_IPROUTE */
+    argv_printf(&argv, "%s -A inet6 add %s/%d dev %s",
+                ROUTE_PATH,
+                network,
+                r6->netbits,
+                device);
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "gw %s", gateway);
+    }
+    if ( (r6->flags & RT_METRIC_DEFINED) && r6->metric > 0)
+    {
+        argv_printf_cat(&argv, " metric %d", r6->metric);
+    }
+#endif  /*ENABLE_IPROUTE*/
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: Linux route -6/-A inet6 add command failed");
+
+#elif defined (TARGET_ANDROID)
+    struct buffer out = alloc_buf_gc(64, &gc);
+
+    buf_printf(&out, "%s/%d %s", network, r6->netbits, device);
+
+    management_android_control(management, "ROUTE6", buf_bptr(&out));
+
+#elif defined (_WIN32)
+
+    if (tt->options.msg_channel)
+    {
+        status = add_route_ipv6_service(r6, tt);
+    }
+    else
+    {
+        struct buffer out = alloc_buf_gc(64, &gc);
+        if (r6->adapter_index)          /* vpn server special route */
+        {
+            buf_printf(&out, "interface=%lu", r6->adapter_index );
+            gateway_needed = true;
+        }
+        else
+        {
+            buf_printf(&out, "interface=%lu", tt->adapter_index );
+        }
+        device = buf_bptr(&out);
+
+        /* netsh interface ipv6 add route 2001:db8::/32 MyTunDevice */
+        argv_printf(&argv, "%s%sc interface ipv6 add route %s/%d %s",
+                    get_win_sys_path(),
+                    NETSH_PATH_SUFFIX,
+                    network,
+                    r6->netbits,
+                    device);
+
+        /* next-hop depends on TUN or TAP mode:
+         * - in TAP mode, we use the "real" next-hop
+         * - in TUN mode we use a special-case link-local address that the tapdrvr
+         *   knows about and will answer ND (neighbor discovery) packets for
+         */
+        if (tt->type == DEV_TYPE_TUN && !gateway_needed)
+        {
+            argv_printf_cat( &argv, " %s", "fe80::8" );
+        }
+        else if (!IN6_IS_ADDR_UNSPECIFIED(&r6->gateway) )
+        {
+            argv_printf_cat( &argv, " %s", gateway );
+        }
+
+#if 0
+        if (r6->flags & RT_METRIC_DEFINED)
+        {
+            argv_printf_cat(&argv, " METRIC %d", r->metric);
+        }
+#endif
+
+        /* in some versions of Windows, routes are persistent across reboots by
+         * default, unless "store=active" is set (pointed out by Tony Lim, thanks)
+         */
+        argv_printf_cat( &argv, " store=active" );
+
+        argv_msg(D_ROUTE, &argv);
+
+        netcmd_semaphore_lock();
+        status = openvpn_execve_check(&argv, es, 0, "ERROR: Windows route add ipv6 command failed");
+        netcmd_semaphore_release();
+    }
+
+#elif defined (TARGET_SOLARIS)
+
+    /* example: route add -inet6 2001:db8::/32 somegateway 0 */
+
+    /* for some reason, routes to tun/tap do not work for me unless I set
+     * "metric 0" - otherwise, the routes will be nicely installed, but
+     * packets will just disappear somewhere.  So we always use "0" now,
+     * unless the route points to "gateway on other interface"...
+     *
+     * (Note: OpenSolaris can not specify host%interface gateways, so we just
+     * use the GW addresses - it seems to still work for fe80:: addresses,
+     * however this is done internally.  NUD maybe?)
+     */
+    argv_printf(&argv, "%s add -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network,
+                r6->netbits,
+                gateway );
+
+    /* on tun (not tap), not "elsewhere"? -> metric 0 */
+    if (tt->type == DEV_TYPE_TUN && !r6->iface)
+    {
+        argv_printf_cat(&argv, "0");
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: Solaris route add -inet6 command failed");
+
+#elif defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)
+
+    argv_printf(&argv, "%s add -inet6 %s/%d",
+                ROUTE_PATH,
+                network,
+                r6->netbits);
+
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "%s", gateway);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "-iface %s", device);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: *BSD route add -inet6 command failed");
+
+#elif defined(TARGET_DARWIN)
+
+    argv_printf(&argv, "%s add -inet6 %s -prefixlen %d",
+                ROUTE_PATH,
+                network, r6->netbits );
+
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "%s", gateway);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "-iface %s", device);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: MacOS X route add -inet6 command failed");
+
+#elif defined(TARGET_OPENBSD)
+
+    argv_printf(&argv, "%s add -inet6 %s -prefixlen %d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway );
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: OpenBSD route add -inet6 command failed");
+
+#elif defined(TARGET_NETBSD)
+
+    argv_printf(&argv, "%s add -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway );
+
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: NetBSD route add -inet6 command failed");
+
+#elif defined(TARGET_AIX)
+
+    argv_printf(&argv, "%s add -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway);
+    argv_msg(D_ROUTE, &argv);
+    status = openvpn_execve_check(&argv, es, 0, "ERROR: AIX route add command failed");
+
+#else  /* if defined(TARGET_LINUX) */
+    msg(M_FATAL, "Sorry, but I don't know how to do 'route ipv6' commands on this operating system.  Try putting your routes in a --route-up script");
+#endif /* if defined(TARGET_LINUX) */
+
+    if (status)
+    {
+        r6->flags |= RT_ADDED;
+    }
+    else
+    {
+        r6->flags &= ~RT_ADDED;
+    }
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+static void
+delete_route(struct route_ipv4 *r,
+             const struct tuntap *tt,
+             unsigned int flags,
+             const struct route_gateway_info *rgi,
+             const struct env_set *es)
+{
+    struct gc_arena gc;
+    struct argv argv = argv_new();
+    const char *network;
+#if !defined(ENABLE_IPROUTE) && !defined(TARGET_AIX)
+    const char *netmask;
+#endif
+#if !defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+    const char *gateway;
+#endif
+    int is_local_route;
+
+    if ((r->flags & (RT_DEFINED|RT_ADDED)) != (RT_DEFINED|RT_ADDED))
+    {
+        return;
+    }
+
+    gc_init(&gc);
+
+    network = print_in_addr_t(r->network, 0, &gc);
+#if !defined(ENABLE_IPROUTE) && !defined(TARGET_AIX)
+    netmask = print_in_addr_t(r->netmask, 0, &gc);
+#endif
+#if !defined(TARGET_LINUX) && !defined(TARGET_ANDROID)
+    gateway = print_in_addr_t(r->gateway, 0, &gc);
+#endif
+
+    is_local_route = local_route(r->network, r->netmask, r->gateway, rgi);
+    if (is_local_route == LR_ERROR)
+    {
+        goto done;
+    }
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+    argv_printf(&argv, "%s route del %s/%d",
+                iproute_path,
+                network,
+                netmask_to_netbits2(r->netmask));
+#else
+    argv_printf(&argv, "%s del -net %s netmask %s",
+                ROUTE_PATH,
+                network,
+                netmask);
+#endif /*ENABLE_IPROUTE*/
+    if (r->flags & RT_METRIC_DEFINED)
+    {
+        argv_printf_cat(&argv, "metric %d", r->metric);
+    }
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route delete command failed");
+
+#elif defined (_WIN32)
+
+    argv_printf(&argv, "%s%sc DELETE %s MASK %s %s",
+                get_win_sys_path(),
+                WIN_ROUTE_PATH_SUFFIX,
+                network,
+                netmask,
+                gateway);
+
+    argv_msg(D_ROUTE, &argv);
+
+    if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_SERVICE)
+    {
+        const bool status = del_route_service(r, tt);
+        msg(D_ROUTE, "Route deletion via service %s", status ? "succeeded" : "failed");
+    }
+    else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_IPAPI)
+    {
+        const bool status = del_route_ipapi(r, tt);
+        msg(D_ROUTE, "Route deletion via IPAPI %s", status ? "succeeded" : "failed");
+    }
+    else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_EXE)
+    {
+        netcmd_semaphore_lock();
+        openvpn_execve_check(&argv, es, 0, "ERROR: Windows route delete command failed");
+        netcmd_semaphore_release();
+    }
+    else if ((flags & ROUTE_METHOD_MASK) == ROUTE_METHOD_ADAPTIVE)
+    {
+        const bool status = del_route_ipapi(r, tt);
+        msg(D_ROUTE, "Route deletion via IPAPI %s [adaptive]", status ? "succeeded" : "failed");
+        if (!status)
+        {
+            msg(D_ROUTE, "Route deletion fallback to route.exe");
+            netcmd_semaphore_lock();
+            openvpn_execve_check(&argv, es, 0, "ERROR: Windows route delete command failed [adaptive]");
+            netcmd_semaphore_release();
+        }
+    }
+    else
+    {
+        ASSERT(0);
+    }
+
+#elif defined (TARGET_SOLARIS)
+
+    argv_printf(&argv, "%s delete %s -netmask %s %s",
+                ROUTE_PATH,
+                network,
+                netmask,
+                gateway);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Solaris route delete command failed");
+
+#elif defined(TARGET_FREEBSD)
+
+    argv_printf(&argv, "%s delete -net %s %s %s",
+                ROUTE_PATH,
+                network,
+                gateway,
+                netmask);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: FreeBSD route delete command failed");
+
+#elif defined(TARGET_DRAGONFLY)
+
+    argv_printf(&argv, "%s delete -net %s %s %s",
+                ROUTE_PATH,
+                network,
+                gateway,
+                netmask);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: DragonFly route delete command failed");
+
+#elif defined(TARGET_DARWIN)
+
+    if (is_on_link(is_local_route, flags, rgi))
+    {
+        argv_printf(&argv, "%s delete -cloning -net %s -netmask %s -interface %s",
+                    ROUTE_PATH,
+                    network,
+                    netmask,
+                    rgi->iface);
+    }
+    else
+    {
+        argv_printf(&argv, "%s delete -net %s %s %s",
+                    ROUTE_PATH,
+                    network,
+                    gateway,
+                    netmask);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: OS X route delete command failed");
+
+#elif defined(TARGET_OPENBSD) || defined(TARGET_NETBSD)
+
+    argv_printf(&argv, "%s delete -net %s %s -netmask %s",
+                ROUTE_PATH,
+                network,
+                gateway,
+                netmask);
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: OpenBSD/NetBSD route delete command failed");
+
+#elif defined(TARGET_ANDROID)
+    msg(M_NONFATAL, "Sorry, deleting routes on Android is not possible. The VpnService API allows routes to be set on connect only.");
+
+#elif defined(TARGET_AIX)
+
+    {
+        int netbits = netmask_to_netbits2(r->netmask);
+        argv_printf(&argv, "%s delete -net %s/%d %s",
+                    ROUTE_PATH,
+                    network, netbits, gateway);
+        argv_msg(D_ROUTE, &argv);
+        openvpn_execve_check(&argv, es, 0, "ERROR: AIX route delete command failed");
+    }
+
+#else  /* if defined(TARGET_LINUX) */
+    msg(M_FATAL, "Sorry, but I don't know how to do 'route' commands on this operating system.  Try putting your routes in a --route-up script");
+#endif /* if defined(TARGET_LINUX) */
+
+done:
+    r->flags &= ~RT_ADDED;
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+void
+delete_route_ipv6(const struct route_ipv6 *r6, const struct tuntap *tt, unsigned int flags, const struct env_set *es)
+{
+    struct gc_arena gc;
+    struct argv argv = argv_new();
+    const char *network;
+    const char *gateway;
+    const char *device = tt->actual_name;
+    bool gateway_needed = false;
+
+    if ((r6->flags & (RT_DEFINED|RT_ADDED)) != (RT_DEFINED|RT_ADDED))
+    {
+        return;
+    }
+
+#ifndef _WIN32
+    if (r6->iface != NULL)              /* vpn server special route */
+    {
+        device = r6->iface;
+        gateway_needed = true;
+    }
+#endif
+
+    gc_init(&gc);
+
+    network = print_in6_addr( r6->network, 0, &gc);
+    gateway = print_in6_addr( r6->gateway, 0, &gc);
+
+#if defined(TARGET_DARWIN)    \
+    || defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)    \
+    || defined(TARGET_OPENBSD) || defined(TARGET_NETBSD)
+
+    /* the BSD platforms cannot specify gateway and interface independently,
+     * but for link-local destinations, we MUST specify the interface, so
+     * we build a combined "$gateway%$interface" gateway string
+     */
+    if (r6->iface != NULL && gateway_needed
+        && IN6_IS_ADDR_LINKLOCAL(&r6->gateway) )        /* fe80::...%intf */
+    {
+        int len = strlen(gateway) + 1 + strlen(r6->iface)+1;
+        char *tmp = gc_malloc( len, true, &gc );
+        snprintf( tmp, len, "%s%%%s", gateway, r6->iface );
+        gateway = tmp;
+    }
+#endif
+
+    msg( M_INFO, "delete_route_ipv6(%s/%d)", network, r6->netbits );
+
+    /* if we used a gateway on "add route", we also need to specify it on
+     * delete, otherwise some OSes will refuse to delete the route
+     */
+    if (tt->type == DEV_TYPE_TAP
+        && !( (r6->flags & RT_METRIC_DEFINED) && r6->metric == 0 ) )
+    {
+        gateway_needed = true;
+    }
+
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+    argv_printf(&argv, "%s -6 route del %s/%d dev %s",
+                iproute_path,
+                network,
+                r6->netbits,
+                device);
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "via %s", gateway);
+    }
+#else  /* ifdef ENABLE_IPROUTE */
+    argv_printf(&argv, "%s -A inet6 del %s/%d dev %s",
+                ROUTE_PATH,
+                network,
+                r6->netbits,
+                device);
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "gw %s", gateway);
+    }
+    if ( (r6->flags & RT_METRIC_DEFINED) && r6->metric > 0)
+    {
+        argv_printf_cat(&argv, " metric %d", r6->metric);
+    }
+#endif  /*ENABLE_IPROUTE*/
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Linux route -6/-A inet6 del command failed");
+
+#elif defined (_WIN32)
+
+    if (tt->options.msg_channel)
+    {
+        del_route_ipv6_service(r6, tt);
+    }
+    else
+    {
+        struct buffer out = alloc_buf_gc(64, &gc);
+        if (r6->adapter_index)          /* vpn server special route */
+        {
+            buf_printf(&out, "interface=%lu", r6->adapter_index );
+            gateway_needed = true;
+        }
+        else
+        {
+            buf_printf(&out, "interface=%lu", tt->adapter_index );
+        }
+        device = buf_bptr(&out);
+
+        /* netsh interface ipv6 delete route 2001:db8::/32 MyTunDevice */
+        argv_printf(&argv, "%s%sc interface ipv6 delete route %s/%d %s",
+                    get_win_sys_path(),
+                    NETSH_PATH_SUFFIX,
+                    network,
+                    r6->netbits,
+                    device);
+
+        /* next-hop depends on TUN or TAP mode:
+         * - in TAP mode, we use the "real" next-hop
+         * - in TUN mode we use a special-case link-local address that the tapdrvr
+         *   knows about and will answer ND (neighbor discovery) packets for
+         * (and "route deletion without specifying next-hop" does not work...)
+         */
+        if (tt->type == DEV_TYPE_TUN && !gateway_needed)
+        {
+            argv_printf_cat( &argv, " %s", "fe80::8" );
+        }
+        else if (!IN6_IS_ADDR_UNSPECIFIED(&r6->gateway) )
+        {
+            argv_printf_cat( &argv, " %s", gateway );
+        }
+
+#if 0
+        if (r6->flags & RT_METRIC_DEFINED)
+        {
+            argv_printf_cat(&argv, "METRIC %d", r->metric);
+        }
+#endif
+
+        /* Windows XP to 7 "just delete" routes, wherever they came from, but
+         * in Windows 8(.1?), if you create them with "store=active", this is
+         * how you should delete them as well (pointed out by Cedric Tabary)
+         */
+        argv_printf_cat( &argv, " store=active" );
+
+        argv_msg(D_ROUTE, &argv);
+
+        netcmd_semaphore_lock();
+        openvpn_execve_check(&argv, es, 0, "ERROR: Windows route delete ipv6 command failed");
+        netcmd_semaphore_release();
+    }
+
+#elif defined (TARGET_SOLARIS)
+
+    /* example: route delete -inet6 2001:db8::/32 somegateway */
+
+    argv_printf(&argv, "%s delete -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network,
+                r6->netbits,
+                gateway );
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: Solaris route delete -inet6 command failed");
+
+#elif defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)
+
+    argv_printf(&argv, "%s delete -inet6 %s/%d",
+                ROUTE_PATH,
+                network,
+                r6->netbits );
+
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "%s", gateway);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "-iface %s", device);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: *BSD route delete -inet6 command failed");
+
+#elif defined(TARGET_DARWIN)
+
+    argv_printf(&argv, "%s delete -inet6 %s -prefixlen %d",
+                ROUTE_PATH,
+                network, r6->netbits );
+
+    if (gateway_needed)
+    {
+        argv_printf_cat(&argv, "%s", gateway);
+    }
+    else
+    {
+        argv_printf_cat(&argv, "-iface %s", device);
+    }
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: MacOS X route delete -inet6 command failed");
+
+#elif defined(TARGET_OPENBSD)
+
+    argv_printf(&argv, "%s delete -inet6 %s -prefixlen %d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway );
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: OpenBSD route delete -inet6 command failed");
+
+#elif defined(TARGET_NETBSD)
+
+    argv_printf(&argv, "%s delete -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway );
+
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: NetBSD route delete -inet6 command failed");
+
+#elif defined(TARGET_AIX)
+
+    argv_printf(&argv, "%s delete -inet6 %s/%d %s",
+                ROUTE_PATH,
+                network, r6->netbits, gateway);
+    argv_msg(D_ROUTE, &argv);
+    openvpn_execve_check(&argv, es, 0, "ERROR: AIX route add command failed");
+
+#else  /* if defined(TARGET_LINUX) */
+    msg(M_FATAL, "Sorry, but I don't know how to do 'route ipv6' commands on this operating system.  Try putting your routes in a --route-down script");
+#endif /* if defined(TARGET_LINUX) */
+
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+/*
+ * The --redirect-gateway option requires OS-specific code below
+ * to get the current default gateway.
+ */
+
+#if defined(_WIN32)
+
+static const MIB_IPFORWARDTABLE *
+get_windows_routing_table(struct gc_arena *gc)
+{
+    ULONG size = 0;
+    PMIB_IPFORWARDTABLE rt = NULL;
+    DWORD status;
+
+    status = GetIpForwardTable(NULL, &size, TRUE);
+    if (status == ERROR_INSUFFICIENT_BUFFER)
+    {
+        rt = (PMIB_IPFORWARDTABLE) gc_malloc(size, false, gc);
+        status = GetIpForwardTable(rt, &size, TRUE);
+        if (status != NO_ERROR)
+        {
+            msg(D_ROUTE, "NOTE: GetIpForwardTable returned error: %s (code=%u)",
+                strerror_win32(status, gc),
+                (unsigned int)status);
+            rt = NULL;
+        }
+    }
+    return rt;
+}
+
+static int
+test_route(const IP_ADAPTER_INFO *adapters,
+           const in_addr_t gateway,
+           DWORD *index)
+{
+    int count = 0;
+    DWORD i = adapter_index_of_ip(adapters, gateway, &count, NULL);
+    if (index)
+    {
+        *index = i;
+    }
+    return count;
+}
+
+static void
+test_route_helper(bool *ret,
+                  int *count,
+                  int *good,
+                  int *ambig,
+                  const IP_ADAPTER_INFO *adapters,
+                  const in_addr_t gateway)
+{
+    int c;
+
+    ++*count;
+    c = test_route(adapters, gateway, NULL);
+    if (c == 0)
+    {
+        *ret = false;
+    }
+    else
+    {
+        ++*good;
+    }
+    if (c > 1)
+    {
+        ++*ambig;
+    }
+}
+
+/*
+ * If we tried to add routes now, would we succeed?
+ */
+bool
+test_routes(const struct route_list *rl, const struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+    const IP_ADAPTER_INFO *adapters = get_adapter_info_list(&gc);
+    bool ret = false;
+    int count = 0;
+    int good = 0;
+    int ambig = 0;
+    int len = -1;
+    bool adapter_up = false;
+
+    if (is_adapter_up(tt, adapters))
+    {
+        ret = true;
+        adapter_up = true;
+
+        if (rl)
+        {
+            struct route_ipv4 *r;
+            for (r = rl->routes, len = 0; r; r = r->next, ++len)
+            {
+                test_route_helper(&ret, &count, &good, &ambig, adapters, r->gateway);
+            }
+
+            if ((rl->flags & RG_ENABLE) && (rl->spec.flags & RTSA_REMOTE_ENDPOINT))
+            {
+                test_route_helper(&ret, &count, &good, &ambig, adapters, rl->spec.remote_endpoint);
+            }
+        }
+    }
+
+    msg(D_ROUTE, "TEST ROUTES: %d/%d succeeded len=%d ret=%d a=%d u/d=%s",
+        good,
+        count,
+        len,
+        (int)ret,
+        ambig,
+        adapter_up ? "up" : "down");
+
+    gc_free(&gc);
+    return ret;
+}
+
+static const MIB_IPFORWARDROW *
+get_default_gateway_row(const MIB_IPFORWARDTABLE *routes)
+{
+    struct gc_arena gc = gc_new();
+    DWORD lowest_metric = MAXDWORD;
+    const MIB_IPFORWARDROW *ret = NULL;
+    int i;
+    int best = -1;
+
+    if (routes)
+    {
+        for (i = 0; i < routes->dwNumEntries; ++i)
+        {
+            const MIB_IPFORWARDROW *row = &routes->table[i];
+            const in_addr_t net = ntohl(row->dwForwardDest);
+            const in_addr_t mask = ntohl(row->dwForwardMask);
+            const DWORD index = row->dwForwardIfIndex;
+            const DWORD metric = row->dwForwardMetric1;
+
+            dmsg(D_ROUTE_DEBUG, "GDGR: route[%d] %s/%s i=%d m=%d",
+                 i,
+                 print_in_addr_t((in_addr_t) net, 0, &gc),
+                 print_in_addr_t((in_addr_t) mask, 0, &gc),
+                 (int)index,
+                 (int)metric);
+
+            if (!net && !mask && metric < lowest_metric)
+            {
+                ret = row;
+                lowest_metric = metric;
+                best = i;
+            }
+        }
+    }
+
+    dmsg(D_ROUTE_DEBUG, "GDGR: best=%d lm=%u", best, (unsigned int)lowest_metric);
+
+    gc_free(&gc);
+    return ret;
+}
+
+void
+get_default_gateway(struct route_gateway_info *rgi)
+{
+    struct gc_arena gc = gc_new();
+
+    const IP_ADAPTER_INFO *adapters = get_adapter_info_list(&gc);
+    const MIB_IPFORWARDTABLE *routes = get_windows_routing_table(&gc);
+    const MIB_IPFORWARDROW *row = get_default_gateway_row(routes);
+    DWORD a_index;
+    const IP_ADAPTER_INFO *ai;
+
+    CLEAR(*rgi);
+
+    if (row)
+    {
+        rgi->gateway.addr = ntohl(row->dwForwardNextHop);
+        if (rgi->gateway.addr)
+        {
+            rgi->flags |= RGI_ADDR_DEFINED;
+            a_index = adapter_index_of_ip(adapters, rgi->gateway.addr, NULL, &rgi->gateway.netmask);
+            if (a_index != TUN_ADAPTER_INDEX_INVALID)
+            {
+                rgi->adapter_index = a_index;
+                rgi->flags |= (RGI_IFACE_DEFINED|RGI_NETMASK_DEFINED);
+                ai = get_adapter(adapters, a_index);
+                if (ai)
+                {
+                    memcpy(rgi->hwaddr, ai->Address, 6);
+                    rgi->flags |= RGI_HWADDR_DEFINED;
+                }
+            }
+        }
+    }
+
+    gc_free(&gc);
+}
+
+static DWORD
+windows_route_find_if_index(const struct route_ipv4 *r, const struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+    DWORD ret = TUN_ADAPTER_INDEX_INVALID;
+    int count = 0;
+    const IP_ADAPTER_INFO *adapters = get_adapter_info_list(&gc);
+    const IP_ADAPTER_INFO *tun_adapter = get_tun_adapter(tt, adapters);
+    bool on_tun = false;
+
+    /* first test on tun interface */
+    if (is_ip_in_adapter_subnet(tun_adapter, r->gateway, NULL))
+    {
+        ret = tun_adapter->Index;
+        count = 1;
+        on_tun = true;
+    }
+    else /* test on other interfaces */
+    {
+        count = test_route(adapters, r->gateway, &ret);
+    }
+
+    if (count == 0)
+    {
+        msg(M_WARN, "Warning: route gateway is not reachable on any active network adapters: %s",
+            print_in_addr_t(r->gateway, 0, &gc));
+        ret = TUN_ADAPTER_INDEX_INVALID;
+    }
+    else if (count > 1)
+    {
+        msg(M_WARN, "Warning: route gateway is ambiguous: %s (%d matches)",
+            print_in_addr_t(r->gateway, 0, &gc),
+            count);
+    }
+
+    dmsg(D_ROUTE_DEBUG, "DEBUG: route find if: on_tun=%d count=%d index=%d",
+         on_tun,
+         count,
+         (int)ret);
+
+    gc_free(&gc);
+    return ret;
+}
+
+/* IPv6 implementation using GetBestRoute2()
+ *   (TBD: dynamic linking so the binary can still run on XP?)
+ * https://msdn.microsoft.com/en-us/library/windows/desktop/aa365922(v=vs.85).aspx
+ * https://msdn.microsoft.com/en-us/library/windows/desktop/aa814411(v=vs.85).aspx
+ */
+void
+get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi6,
+                         const struct in6_addr *dest)
+{
+    struct gc_arena gc = gc_new();
+    MIB_IPFORWARD_ROW2 BestRoute;
+    SOCKADDR_INET DestinationAddress, BestSourceAddress;
+    DWORD BestIfIndex;
+    DWORD status;
+    NET_LUID InterfaceLuid;
+
+    CLEAR(*rgi6);
+    CLEAR(InterfaceLuid);               /* cleared = not used for lookup */
+    CLEAR(DestinationAddress);
+
+    DestinationAddress.si_family = AF_INET6;
+    if (dest)
+    {
+        DestinationAddress.Ipv6.sin6_addr = *dest;
+    }
+
+    status = GetBestInterfaceEx( &DestinationAddress, &BestIfIndex );
+
+    if (status != NO_ERROR)
+    {
+        msg(D_ROUTE, "NOTE: GetBestInterfaceEx returned error: %s (code=%u)",
+            strerror_win32(status, &gc),
+            (unsigned int)status);
+        goto done;
+    }
+
+    msg( D_ROUTE, "GetBestInterfaceEx() returned if=%d", (int) BestIfIndex );
+
+    status = GetBestRoute2( &InterfaceLuid, BestIfIndex, NULL,
+                            &DestinationAddress, 0,
+                            &BestRoute, &BestSourceAddress );
+
+    if (status != NO_ERROR)
+    {
+        msg(D_ROUTE, "NOTE: GetIpForwardEntry2 returned error: %s (code=%u)",
+            strerror_win32(status, &gc),
+            (unsigned int)status);
+        goto done;
+    }
+
+    msg( D_ROUTE, "GDG6: II=%lu DP=%s/%d NH=%s",
+         BestRoute.InterfaceIndex,
+         print_in6_addr( BestRoute.DestinationPrefix.Prefix.Ipv6.sin6_addr, 0, &gc),
+         BestRoute.DestinationPrefix.PrefixLength,
+         print_in6_addr( BestRoute.NextHop.Ipv6.sin6_addr, 0, &gc) );
+    msg( D_ROUTE, "GDG6: Metric=%d, Loopback=%d, AA=%d, I=%d",
+         (int) BestRoute.Metric,
+         (int) BestRoute.Loopback,
+         (int) BestRoute.AutoconfigureAddress,
+         (int) BestRoute.Immortal );
+
+    rgi6->gateway.addr_ipv6 = BestRoute.NextHop.Ipv6.sin6_addr;
+    rgi6->adapter_index     = BestRoute.InterfaceIndex;
+    rgi6->flags |= RGI_ADDR_DEFINED | RGI_IFACE_DEFINED;
+
+    /* on-link is signalled by receiving an empty (::) NextHop */
+    if (IN6_IS_ADDR_UNSPECIFIED(&BestRoute.NextHop.Ipv6.sin6_addr) )
+    {
+        rgi6->flags |= RGI_ON_LINK;
+    }
+
+done:
+    gc_free(&gc);
+}
+
+bool
+add_route_ipapi(const struct route_ipv4 *r, const struct tuntap *tt, DWORD adapter_index)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+    DWORD status;
+    const DWORD if_index = (adapter_index == TUN_ADAPTER_INDEX_INVALID) ? windows_route_find_if_index(r, tt) : adapter_index;
+
+    if (if_index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        MIB_IPFORWARDROW fr;
+        CLEAR(fr);
+        fr.dwForwardDest = htonl(r->network);
+        fr.dwForwardMask = htonl(r->netmask);
+        fr.dwForwardPolicy = 0;
+        fr.dwForwardNextHop = htonl(r->gateway);
+        fr.dwForwardIfIndex = if_index;
+        fr.dwForwardType = 4; /* the next hop is not the final dest */
+        fr.dwForwardProto = 3; /* PROTO_IP_NETMGMT */
+        fr.dwForwardAge = 0;
+        fr.dwForwardNextHopAS = 0;
+        fr.dwForwardMetric1 = (r->flags & RT_METRIC_DEFINED) ? r->metric : 1;
+        fr.dwForwardMetric2 = METRIC_NOT_USED;
+        fr.dwForwardMetric3 = METRIC_NOT_USED;
+        fr.dwForwardMetric4 = METRIC_NOT_USED;
+        fr.dwForwardMetric5 = METRIC_NOT_USED;
+
+        if ((r->network & r->netmask) != r->network)
+        {
+            msg(M_WARN, "Warning: address %s is not a network address in relation to netmask %s",
+                print_in_addr_t(r->network, 0, &gc),
+                print_in_addr_t(r->netmask, 0, &gc));
+        }
+
+        status = CreateIpForwardEntry(&fr);
+
+        if (status == NO_ERROR)
+        {
+            ret = true;
+        }
+        else
+        {
+            /* failed, try increasing the metric to work around Vista issue */
+            const unsigned int forward_metric_limit = 2048; /* iteratively retry higher metrics up to this limit */
+
+            for (; fr.dwForwardMetric1 <= forward_metric_limit; ++fr.dwForwardMetric1)
+            {
+                /* try a different forward type=3 ("the next hop is the final dest") in addition to 4.
+                 * --redirect-gateway over RRAS seems to need this. */
+                for (fr.dwForwardType = 4; fr.dwForwardType >= 3; --fr.dwForwardType)
+                {
+                    status = CreateIpForwardEntry(&fr);
+                    if (status == NO_ERROR)
+                    {
+                        msg(D_ROUTE, "ROUTE: CreateIpForwardEntry succeeded with dwForwardMetric1=%u and dwForwardType=%u",
+                            (unsigned int)fr.dwForwardMetric1,
+                            (unsigned int)fr.dwForwardType);
+                        ret = true;
+                        goto doublebreak;
+                    }
+                    else if (status != ERROR_BAD_ARGUMENTS)
+                    {
+                        goto doublebreak;
+                    }
+                }
+            }
+
+doublebreak:
+            if (status != NO_ERROR)
+            {
+                msg(M_WARN, "ROUTE: route addition failed using CreateIpForwardEntry: %s [status=%u if_index=%u]",
+                    strerror_win32(status, &gc),
+                    (unsigned int)status,
+                    (unsigned int)if_index);
+            }
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+bool
+del_route_ipapi(const struct route_ipv4 *r, const struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+    DWORD status;
+    const DWORD if_index = windows_route_find_if_index(r, tt);
+
+    if (if_index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        MIB_IPFORWARDROW fr;
+        CLEAR(fr);
+
+        fr.dwForwardDest = htonl(r->network);
+        fr.dwForwardMask = htonl(r->netmask);
+        fr.dwForwardPolicy = 0;
+        fr.dwForwardNextHop = htonl(r->gateway);
+        fr.dwForwardIfIndex = if_index;
+
+        status = DeleteIpForwardEntry(&fr);
+
+        if (status == NO_ERROR)
+        {
+            ret = true;
+        }
+        else
+        {
+            msg(M_WARN, "ROUTE: route deletion failed using DeleteIpForwardEntry: %s",
+                strerror_win32(status, &gc));
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+do_route_service(const bool add, const route_message_t *rt, const size_t size, HANDLE pipe)
+{
+    DWORD len;
+    bool ret = false;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+
+    if (!WriteFile(pipe, rt, size, &len, NULL)
+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "ROUTE: could not talk to service: %s [%lu]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+        goto out;
+    }
+
+    if (ack.error_number != NO_ERROR)
+    {
+        msg(M_WARN, "ROUTE: route %s failed using service: %s [status=%u if_index=%d]",
+            (add ? "addition" : "deletion"), strerror_win32(ack.error_number, &gc),
+            ack.error_number, rt->iface.index);
+        goto out;
+    }
+
+    ret = true;
+
+out:
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+do_route_ipv4_service(const bool add, const struct route_ipv4 *r, const struct tuntap *tt)
+{
+    DWORD if_index = windows_route_find_if_index(r, tt);
+    if (if_index == ~0)
+    {
+        return false;
+    }
+
+    route_message_t msg = {
+        .header = {
+            (add ? msg_add_route : msg_del_route),
+            sizeof(route_message_t),
+            0
+        },
+        .family = AF_INET,
+        .prefix.ipv4.s_addr = htonl(r->network),
+        .gateway.ipv4.s_addr = htonl(r->gateway),
+        .iface = { .index = if_index, .name = "" },
+        .metric = (r->flags & RT_METRIC_DEFINED ? r->metric : -1)
+    };
+
+    netmask_to_netbits(r->network, r->netmask, &msg.prefix_len);
+    if (msg.prefix_len == -1)
+    {
+        msg.prefix_len = 32;
+    }
+
+    return do_route_service(add, &msg, sizeof(msg), tt->options.msg_channel);
+}
+
+static bool
+do_route_ipv6_service(const bool add, const struct route_ipv6 *r, const struct tuntap *tt)
+{
+    bool status;
+    route_message_t msg = {
+        .header = {
+            (add ? msg_add_route : msg_del_route),
+            sizeof(route_message_t),
+            0
+        },
+        .family = AF_INET6,
+        .prefix.ipv6 = r->network,
+        .prefix_len = r->netbits,
+        .gateway.ipv6 = r->gateway,
+        .iface = { .index = tt->adapter_index, .name = "" },
+        .metric = ( (r->flags & RT_METRIC_DEFINED) ? r->metric : -1)
+    };
+
+    if (r->adapter_index)               /* vpn server special route */
+    {
+        msg.iface.index = r->adapter_index;
+    }
+
+    /* In TUN mode we use a special link-local address as the next hop.
+     * The tapdrvr knows about it and will answer neighbor discovery packets.
+     * (only do this for routes actually using the tun/tap device)
+     */
+    if (tt->type == DEV_TYPE_TUN
+	 && msg.iface.index == tt->adapter_index )
+    {
+        inet_pton(AF_INET6, "fe80::8", &msg.gateway.ipv6);
+    }
+
+    if (msg.iface.index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        strncpy(msg.iface.name, tt->actual_name, sizeof(msg.iface.name));
+        msg.iface.name[sizeof(msg.iface.name) - 1] = '\0';
+    }
+
+    status = do_route_service(add, &msg, sizeof(msg), tt->options.msg_channel);
+    msg(D_ROUTE, "IPv6 route %s via service %s",
+        add ? "addition" : "deletion",
+        status ? "succeeded" : "failed");
+    return status;
+}
+
+static bool
+add_route_service(const struct route_ipv4 *r, const struct tuntap *tt)
+{
+    return do_route_ipv4_service(true, r, tt);
+}
+
+static bool
+del_route_service(const struct route_ipv4 *r, const struct tuntap *tt)
+{
+    return do_route_ipv4_service(false, r, tt);
+}
+
+static bool
+add_route_ipv6_service(const struct route_ipv6 *r, const struct tuntap *tt)
+{
+    return do_route_ipv6_service(true, r, tt);
+}
+
+static bool
+del_route_ipv6_service(const struct route_ipv6 *r, const struct tuntap *tt)
+{
+    return do_route_ipv6_service(false, r, tt);
+}
+
+static const char *
+format_route_entry(const MIB_IPFORWARDROW *r, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    buf_printf(&out, "%s %s %s p=%d i=%d t=%d pr=%d a=%d h=%d m=%d/%d/%d/%d/%d",
+               print_in_addr_t(r->dwForwardDest, IA_NET_ORDER, gc),
+               print_in_addr_t(r->dwForwardMask, IA_NET_ORDER, gc),
+               print_in_addr_t(r->dwForwardNextHop, IA_NET_ORDER, gc),
+               (int)r->dwForwardPolicy,
+               (int)r->dwForwardIfIndex,
+               (int)r->dwForwardType,
+               (int)r->dwForwardProto,
+               (int)r->dwForwardAge,
+               (int)r->dwForwardNextHopAS,
+               (int)r->dwForwardMetric1,
+               (int)r->dwForwardMetric2,
+               (int)r->dwForwardMetric3,
+               (int)r->dwForwardMetric4,
+               (int)r->dwForwardMetric5);
+    return BSTR(&out);
+}
+
+/*
+ * Show current routing table
+ */
+void
+show_routes(int msglev)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+
+    const MIB_IPFORWARDTABLE *rt = get_windows_routing_table(&gc);
+
+    msg(msglev, "SYSTEM ROUTING TABLE");
+    if (rt)
+    {
+        for (i = 0; i < rt->dwNumEntries; ++i)
+        {
+            msg(msglev, "%s", format_route_entry(&rt->table[i], &gc));
+        }
+    }
+    gc_free(&gc);
+}
+
+#elif defined(TARGET_LINUX) || defined(TARGET_ANDROID)
+
+void
+get_default_gateway(struct route_gateway_info *rgi)
+{
+    struct gc_arena gc = gc_new();
+    int sd = -1;
+    char best_name[16];
+    best_name[0] = 0;
+
+    CLEAR(*rgi);
+
+#ifndef TARGET_ANDROID
+    /* get default gateway IP addr */
+    {
+        FILE *fp = fopen("/proc/net/route", "r");
+        if (fp)
+        {
+            char line[256];
+            int count = 0;
+            unsigned int lowest_metric = UINT_MAX;
+            in_addr_t best_gw = 0;
+            bool found = false;
+            while (fgets(line, sizeof(line), fp) != NULL)
+            {
+                if (count)
+                {
+                    unsigned int net_x = 0;
+                    unsigned int mask_x = 0;
+                    unsigned int gw_x = 0;
+                    unsigned int metric = 0;
+                    unsigned int flags = 0;
+                    char name[16];
+                    name[0] = 0;
+                    const int np = sscanf(line, "%15s\t%x\t%x\t%x\t%*s\t%*s\t%d\t%x",
+                                          name,
+                                          &net_x,
+                                          &gw_x,
+                                          &flags,
+                                          &metric,
+                                          &mask_x);
+                    if (np == 6 && (flags & IFF_UP))
+                    {
+                        const in_addr_t net = ntohl(net_x);
+                        const in_addr_t mask = ntohl(mask_x);
+                        const in_addr_t gw = ntohl(gw_x);
+
+                        if (!net && !mask && metric < lowest_metric)
+                        {
+                            found = true;
+                            best_gw = gw;
+                            strcpy(best_name, name);
+                            lowest_metric = metric;
+                        }
+                    }
+                }
+                ++count;
+            }
+            fclose(fp);
+
+            if (found)
+            {
+                rgi->gateway.addr = best_gw;
+                rgi->flags |= RGI_ADDR_DEFINED;
+                if (!rgi->gateway.addr && best_name[0])
+                {
+                    rgi->flags |= RGI_ON_LINK;
+                }
+            }
+        }
+    }
+#else  /* ifndef TARGET_ANDROID */
+    /* Android, set some pseudo GW, addr is in host byte order,
+     * Determining the default GW on Android 5.0+ is non trivial
+     * and serves almost no purpose since OpenVPN only uses the
+     * default GW address to add routes for networks that should
+     * NOT be routed over the VPN. Using a well known address
+     * (127.'d'.'g'.'w') for the default GW make detecting
+     * these routes easier from the controlling app.
+     */
+    rgi->gateway.addr = 127 << 24 | 'd' << 16 | 'g' << 8 | 'w';
+    rgi->flags |= RGI_ADDR_DEFINED;
+    strcpy(best_name, "android-gw");
+#endif /* ifndef TARGET_ANDROID */
+
+    /* scan adapter list */
+    if (rgi->flags & RGI_ADDR_DEFINED)
+    {
+        struct ifreq *ifr, *ifend;
+        in_addr_t addr, netmask;
+        struct ifreq ifreq;
+        struct ifconf ifc;
+        struct ifreq ifs[20]; /* Maximum number of interfaces to scan */
+
+        if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
+        {
+            msg(M_WARN, "GDG: socket() failed");
+            goto done;
+        }
+        ifc.ifc_len = sizeof(ifs);
+        ifc.ifc_req = ifs;
+        if (ioctl(sd, SIOCGIFCONF, &ifc) < 0)
+        {
+            msg(M_WARN, "GDG: ioctl(SIOCGIFCONF) failed");
+            goto done;
+        }
+
+        /* scan through interface list */
+        ifend = ifs + (ifc.ifc_len / sizeof(struct ifreq));
+        for (ifr = ifc.ifc_req; ifr < ifend; ifr++)
+        {
+            if (ifr->ifr_addr.sa_family == AF_INET)
+            {
+                /* get interface addr */
+                addr = ntohl(((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr);
+
+                /* get interface name */
+                strncpynt(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
+
+                /* check that the interface is up */
+                if (ioctl(sd, SIOCGIFFLAGS, &ifreq) < 0)
+                {
+                    continue;
+                }
+                if (!(ifreq.ifr_flags & IFF_UP))
+                {
+                    continue;
+                }
+
+                if (rgi->flags & RGI_ON_LINK)
+                {
+                    /* check that interface name of current interface
+                     * matches interface name of best default route */
+                    if (strcmp(ifreq.ifr_name, best_name))
+                    {
+                        continue;
+                    }
+#if 0
+                    /* if point-to-point link, use remote addr as route gateway */
+                    if ((ifreq.ifr_flags & IFF_POINTOPOINT) && ioctl(sd, SIOCGIFDSTADDR, &ifreq) >= 0)
+                    {
+                        rgi->gateway.addr = ntohl(((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr);
+                        if (rgi->gateway.addr)
+                        {
+                            rgi->flags &= ~RGI_ON_LINK;
+                        }
+                    }
+#endif
+                }
+                else
+                {
+                    /* get interface netmask */
+                    if (ioctl(sd, SIOCGIFNETMASK, &ifreq) < 0)
+                    {
+                        continue;
+                    }
+                    netmask = ntohl(((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr);
+
+                    /* check that interface matches default route */
+                    if (((rgi->gateway.addr ^ addr) & netmask) != 0)
+                    {
+                        continue;
+                    }
+
+                    /* save netmask */
+                    rgi->gateway.netmask = netmask;
+                    rgi->flags |= RGI_NETMASK_DEFINED;
+                }
+
+                /* save iface name */
+                strncpynt(rgi->iface, ifreq.ifr_name, sizeof(rgi->iface));
+                rgi->flags |= RGI_IFACE_DEFINED;
+
+                /* now get the hardware address. */
+                memset(&ifreq.ifr_hwaddr, 0, sizeof(struct sockaddr));
+                if (ioctl(sd, SIOCGIFHWADDR, &ifreq) < 0)
+                {
+                    msg(M_WARN, "GDG: SIOCGIFHWADDR(%s) failed", ifreq.ifr_name);
+                    goto done;
+                }
+                memcpy(rgi->hwaddr, &ifreq.ifr_hwaddr.sa_data, 6);
+                rgi->flags |= RGI_HWADDR_DEFINED;
+
+                break;
+            }
+        }
+    }
+
+done:
+    if (sd >= 0)
+    {
+        close(sd);
+    }
+    gc_free(&gc);
+}
+
+/* IPv6 implementation using netlink
+ * http://www.linuxjournal.com/article/7356
+ * netlink(3), netlink(7), rtnetlink(7)
+ * http://www.virtualbox.org/svn/vbox/trunk/src/VBox/NetworkServices/NAT/rtmon_linux.c
+ */
+struct rtreq {
+    struct nlmsghdr nh;
+    struct rtmsg rtm;
+    char attrbuf[512];
+};
+
+void
+get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi6,
+                         const struct in6_addr *dest)
+{
+    int nls = -1;
+    struct rtreq rtreq;
+    struct rtattr *rta;
+
+    char rtbuf[2000];
+    ssize_t ssize;
+
+    CLEAR(*rgi6);
+
+    nls = socket( PF_NETLINK, SOCK_RAW, NETLINK_ROUTE );
+    if (nls < 0)
+    {
+        msg(M_WARN|M_ERRNO, "GDG6: socket() failed" ); goto done;
+    }
+
+    /* bind() is not needed, no unsolicited msgs coming in */
+
+    /* request best matching route, see netlink(7) for explanations
+     */
+    CLEAR(rtreq);
+    rtreq.nh.nlmsg_type = RTM_GETROUTE;
+    rtreq.nh.nlmsg_flags = NLM_F_REQUEST;       /* best match only */
+    rtreq.rtm.rtm_family = AF_INET6;
+    rtreq.rtm.rtm_src_len = 0;                  /* not source dependent */
+    rtreq.rtm.rtm_dst_len = 128;                /* exact dst */
+    rtreq.rtm.rtm_table = RT_TABLE_MAIN;
+    rtreq.rtm.rtm_protocol = RTPROT_UNSPEC;
+    rtreq.nh.nlmsg_len = NLMSG_SPACE(sizeof(rtreq.rtm));
+
+    /* set RTA_DST for target IPv6 address we want */
+    rta = (struct rtattr *)(((char *) &rtreq)+NLMSG_ALIGN(rtreq.nh.nlmsg_len));
+    rta->rta_type = RTA_DST;
+    rta->rta_len = RTA_LENGTH(16);
+    rtreq.nh.nlmsg_len = NLMSG_ALIGN(rtreq.nh.nlmsg_len)
+                         +RTA_LENGTH(16);
+
+    if (dest == NULL)                   /* ::, unspecified */
+    {
+        memset( RTA_DATA(rta), 0, 16 ); /* :: = all-zero */
+    }
+    else
+    {
+        memcpy( RTA_DATA(rta), (void *)dest, 16 );
+    }
+
+    /* send and receive reply */
+    if (send( nls, &rtreq, rtreq.nh.nlmsg_len, 0 ) < 0)
+    {
+        msg(M_WARN|M_ERRNO, "GDG6: send() failed" ); goto done;
+    }
+
+    ssize = recv(nls, rtbuf, sizeof(rtbuf), MSG_TRUNC);
+
+    if (ssize < 0)
+    {
+        msg(M_WARN|M_ERRNO, "GDG6: recv() failed" ); goto done;
+    }
+
+    if (ssize > sizeof(rtbuf))
+    {
+        msg(M_WARN, "get_default_gateway_ipv6: returned message too big for buffer (%d>%d)", (int)ssize, (int)sizeof(rtbuf) );
+        goto done;
+    }
+
+    struct nlmsghdr *nh;
+
+    for (nh = (struct nlmsghdr *)rtbuf;
+         NLMSG_OK(nh, ssize);
+         nh = NLMSG_NEXT(nh, ssize))
+    {
+        struct rtmsg *rtm;
+        int attrlen;
+
+        if (nh->nlmsg_type == NLMSG_DONE)
+        {
+            break;
+        }
+
+        if (nh->nlmsg_type == NLMSG_ERROR)
+        {
+            struct nlmsgerr *ne = (struct nlmsgerr *)NLMSG_DATA(nh);
+
+            /* since linux-4.11 -ENETUNREACH is returned when no route can be
+             * found. Don't print any error message in this case */
+            if (ne->error != -ENETUNREACH)
+            {
+                msg(M_WARN, "GDG6: NLMSG_ERROR: error %s\n",
+                    strerror(-ne->error));
+            }
+            break;
+        }
+
+        if (nh->nlmsg_type != RTM_NEWROUTE)
+        {
+            /* shouldn't happen */
+            msg(M_WARN, "GDG6: unexpected msg_type %d", nh->nlmsg_type );
+            continue;
+        }
+
+        rtm = (struct rtmsg *)NLMSG_DATA(nh);
+        attrlen = RTM_PAYLOAD(nh);
+
+        /* we're only looking for routes in the main table, as "we have
+         * no IPv6" will lead to a lookup result in "Local" (::/0 reject)
+         */
+        if (rtm->rtm_family != AF_INET6
+            || rtm->rtm_table != RT_TABLE_MAIN)
+        {
+            continue;
+        }                               /* we're not interested */
+
+        for (rta = RTM_RTA(rtm);
+             RTA_OK(rta, attrlen);
+             rta = RTA_NEXT(rta, attrlen))
+        {
+            if (rta->rta_type == RTA_GATEWAY)
+            {
+                if (RTA_PAYLOAD(rta) != sizeof(struct in6_addr) )
+                {
+                    msg(M_WARN, "GDG6: RTA_GW size mismatch"); continue;
+                }
+                rgi6->gateway.addr_ipv6 = *(struct in6_addr *) RTA_DATA(rta);
+                rgi6->flags |= RGI_ADDR_DEFINED;
+            }
+            else if (rta->rta_type == RTA_OIF)
+            {
+                char ifname[IF_NAMESIZE+1];
+                int oif;
+                if (RTA_PAYLOAD(rta) != sizeof(oif) )
+                {
+                    msg(M_WARN, "GDG6: oif size mismatch"); continue;
+                }
+
+                memcpy(&oif, RTA_DATA(rta), sizeof(oif));
+                if_indextoname(oif,ifname);
+                strncpy( rgi6->iface, ifname, sizeof(rgi6->iface)-1 );
+                rgi6->flags |= RGI_IFACE_DEFINED;
+            }
+        }
+    }
+
+    /* if we have an interface but no gateway, the destination is on-link */
+    if ( ( rgi6->flags & (RGI_IFACE_DEFINED|RGI_ADDR_DEFINED) ) ==
+         RGI_IFACE_DEFINED)
+    {
+        rgi6->flags |= (RGI_ADDR_DEFINED | RGI_ON_LINK);
+        if (dest)
+        {
+            rgi6->gateway.addr_ipv6 = *dest;
+        }
+    }
+
+done:
+    if (nls >= 0)
+    {
+        close(nls);
+    }
+}
+
+#elif defined(TARGET_DARWIN) || defined(TARGET_SOLARIS)    \
+    || defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)    \
+    || defined(TARGET_OPENBSD) || defined(TARGET_NETBSD)
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <net/route.h>
+#include <net/if_dl.h>
+
+struct rtmsg {
+    struct rt_msghdr m_rtm;
+    char m_space[512];
+};
+
+/* the route socket code is identical for all 4 supported BSDs and for
+ * MacOS X (Darwin), with one crucial difference: when going from
+ * 32 bit to 64 bit, the BSDs increased the structure size but kept
+ * source code compatibility by keeping the use of "long", while
+ * MacOS X decided to keep binary compatibility by *changing* the API
+ * to use "uint32_t", thus 32 bit on all OS X variants
+ *
+ * We used to have a large amount of duplicate code here which really
+ * differed only in this (long) vs. (uint32_t) - IMHO, worse than
+ * having a combined block for all BSDs with this single #ifdef inside
+ */
+
+#if defined(TARGET_DARWIN)
+#define ROUNDUP(a) \
+    ((a) > 0 ? (1 + (((a) - 1) | (sizeof(uint32_t) - 1))) : sizeof(uint32_t))
+#else
+#define ROUNDUP(a) \
+    ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
+#endif
+
+#if defined(TARGET_SOLARIS)
+#define NEXTADDR(w, u) \
+    if (rtm_addrs & (w)) { \
+        l = ROUNDUP(sizeof(u)); memmove(cp, &(u), l); cp += l; \
+    }
+
+#define ADVANCE(x, n) (x += ROUNDUP(sizeof(struct sockaddr_in)))
+#else  /* if defined(TARGET_SOLARIS) */
+#define NEXTADDR(w, u) \
+    if (rtm_addrs & (w)) { \
+        l = ROUNDUP( ((struct sockaddr *)&(u))->sa_len); memmove(cp, &(u), l); cp += l; \
+    }
+
+#define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
+#endif
+
+#define max(a,b) ((a) > (b) ? (a) : (b))
+
+void
+get_default_gateway(struct route_gateway_info *rgi)
+{
+    struct gc_arena gc = gc_new();
+    struct rtmsg m_rtmsg;
+    int sockfd = -1;
+    int seq, l, pid, rtm_addrs;
+    unsigned int i;
+    struct sockaddr so_dst, so_mask;
+    char *cp = m_rtmsg.m_space;
+    struct sockaddr *gate = NULL, *ifp = NULL, *sa;
+    struct  rt_msghdr *rtm_aux;
+
+#define rtm m_rtmsg.m_rtm
+
+    CLEAR(*rgi);
+
+    /* setup data to send to routing socket */
+    pid = getpid();
+    seq = 0;
+    rtm_addrs = RTA_DST | RTA_NETMASK | RTA_IFP;
+
+    bzero(&m_rtmsg, sizeof(m_rtmsg));
+    bzero(&so_dst, sizeof(so_dst));
+    bzero(&so_mask, sizeof(so_mask));
+    bzero(&rtm, sizeof(struct rt_msghdr));
+
+    rtm.rtm_type = RTM_GET;
+    rtm.rtm_flags = RTF_UP | RTF_GATEWAY;
+    rtm.rtm_version = RTM_VERSION;
+    rtm.rtm_seq = ++seq;
+#ifdef TARGET_OPENBSD
+    rtm.rtm_tableid = getrtable();
+#endif
+    rtm.rtm_addrs = rtm_addrs;
+
+    so_dst.sa_family = AF_INET;
+    so_mask.sa_family = AF_INET;
+
+#ifndef TARGET_SOLARIS
+    so_dst.sa_len = sizeof(struct sockaddr_in);
+    so_mask.sa_len = sizeof(struct sockaddr_in);
+#endif
+
+    NEXTADDR(RTA_DST, so_dst);
+    NEXTADDR(RTA_NETMASK, so_mask);
+
+    rtm.rtm_msglen = l = cp - (char *)&m_rtmsg;
+
+    /* transact with routing socket */
+    sockfd = socket(PF_ROUTE, SOCK_RAW, 0);
+    if (sockfd < 0)
+    {
+        msg(M_WARN, "GDG: socket #1 failed");
+        goto done;
+    }
+    if (write(sockfd, (char *)&m_rtmsg, l) < 0)
+    {
+        msg(M_WARN, "GDG: problem writing to routing socket");
+        goto done;
+    }
+    do
+    {
+        l = read(sockfd, (char *)&m_rtmsg, sizeof(m_rtmsg));
+    } while (l > 0 && (rtm.rtm_seq != seq || rtm.rtm_pid != pid));
+    close(sockfd);
+    sockfd = -1;
+
+    /* extract return data from routing socket */
+    rtm_aux = &rtm;
+    cp = ((char *)(rtm_aux + 1));
+    if (rtm_aux->rtm_addrs)
+    {
+        for (i = 1; i; i <<= 1)
+        {
+            if (i & rtm_aux->rtm_addrs)
+            {
+                sa = (struct sockaddr *)cp;
+                if (i == RTA_GATEWAY)
+                {
+                    gate = sa;
+                }
+                else if (i == RTA_IFP)
+                {
+                    ifp = sa;
+                }
+                ADVANCE(cp, sa);
+            }
+        }
+    }
+    else
+    {
+        goto done;
+    }
+
+    /* get gateway addr and interface name */
+    if (gate != NULL)
+    {
+        /* get default gateway addr */
+        rgi->gateway.addr = ntohl(((struct sockaddr_in *)gate)->sin_addr.s_addr);
+        if (rgi->gateway.addr)
+        {
+            rgi->flags |= RGI_ADDR_DEFINED;
+        }
+
+        if (ifp)
+        {
+            /* get interface name */
+            const struct sockaddr_dl *adl = (struct sockaddr_dl *) ifp;
+            if (adl->sdl_nlen && adl->sdl_nlen < sizeof(rgi->iface))
+            {
+                memcpy(rgi->iface, adl->sdl_data, adl->sdl_nlen);
+                rgi->iface[adl->sdl_nlen] = '\0';
+                rgi->flags |= RGI_IFACE_DEFINED;
+            }
+        }
+    }
+
+    /* get netmask of interface that owns default gateway */
+    if (rgi->flags & RGI_IFACE_DEFINED)
+    {
+        struct ifreq ifr;
+
+        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+        if (sockfd < 0)
+        {
+            msg(M_WARN, "GDG: socket #2 failed");
+            goto done;
+        }
+
+        CLEAR(ifr);
+        ifr.ifr_addr.sa_family = AF_INET;
+        strncpynt(ifr.ifr_name, rgi->iface, IFNAMSIZ);
+
+        if (ioctl(sockfd, SIOCGIFNETMASK, (char *)&ifr) < 0)
+        {
+            msg(M_WARN, "GDG: ioctl #1 failed");
+            goto done;
+        }
+        close(sockfd);
+        sockfd = -1;
+
+        rgi->gateway.netmask = ntohl(((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr.s_addr);
+        rgi->flags |= RGI_NETMASK_DEFINED;
+    }
+
+    /* try to read MAC addr associated with interface that owns default gateway */
+    if (rgi->flags & RGI_IFACE_DEFINED)
+    {
+        struct ifconf ifc;
+        struct ifreq *ifr;
+        const int bufsize = 4096;
+        char *buffer;
+
+        buffer = (char *) gc_malloc(bufsize, true, &gc);
+        sockfd = socket(AF_INET, SOCK_DGRAM, 0);
+        if (sockfd < 0)
+        {
+            msg(M_WARN, "GDG: socket #3 failed");
+            goto done;
+        }
+
+        ifc.ifc_len = bufsize;
+        ifc.ifc_buf = buffer;
+
+        if (ioctl(sockfd, SIOCGIFCONF, (char *)&ifc) < 0)
+        {
+            msg(M_WARN, "GDG: ioctl #2 failed");
+            goto done;
+        }
+        close(sockfd);
+        sockfd = -1;
+
+        for (cp = buffer; cp <= buffer + ifc.ifc_len - sizeof(struct ifreq); )
+        {
+            ifr = (struct ifreq *)cp;
+#if defined(TARGET_SOLARIS)
+            const size_t len = sizeof(ifr->ifr_name) + sizeof(ifr->ifr_addr);
+#else
+            const size_t len = sizeof(ifr->ifr_name) + max(sizeof(ifr->ifr_addr), ifr->ifr_addr.sa_len);
+#endif
+
+            if (!ifr->ifr_addr.sa_family)
+            {
+                break;
+            }
+            if (!strncmp(ifr->ifr_name, rgi->iface, IFNAMSIZ))
+            {
+                if (ifr->ifr_addr.sa_family == AF_LINK)
+                {
+                    struct sockaddr_dl *sdl = (struct sockaddr_dl *)&ifr->ifr_addr;
+                    memcpy(rgi->hwaddr, LLADDR(sdl), 6);
+                    rgi->flags |= RGI_HWADDR_DEFINED;
+                }
+            }
+            cp += len;
+        }
+    }
+
+done:
+    if (sockfd >= 0)
+    {
+        close(sockfd);
+    }
+    gc_free(&gc);
+}
+
+/* BSD implementation using routing socket (as does IPv4)
+ * (the code duplication is somewhat unavoidable if we want this to
+ * work on OpenSolaris as well.  *sigh*)
+ */
+
+/* Solaris has no length field - this is ugly, but less #ifdef in total
+ */
+#if defined(TARGET_SOLARIS)
+#undef ADVANCE
+#define ADVANCE(x, n) (x += ROUNDUP(sizeof(struct sockaddr_in6)))
+#endif
+
+void
+get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi6,
+                         const struct in6_addr *dest)
+{
+
+    struct rtmsg m_rtmsg;
+    int sockfd = -1;
+    int seq, l, pid, rtm_addrs;
+    unsigned int i;
+    struct sockaddr_in6 so_dst, so_mask;
+    char *cp = m_rtmsg.m_space;
+    struct sockaddr *gate = NULL, *ifp = NULL, *sa;
+    struct rt_msghdr *rtm_aux;
+
+    CLEAR(*rgi6);
+
+    /* setup data to send to routing socket */
+    pid = getpid();
+    seq = 0;
+    rtm_addrs = RTA_DST | RTA_NETMASK | RTA_IFP;
+
+    bzero(&m_rtmsg, sizeof(m_rtmsg));
+    bzero(&so_dst, sizeof(so_dst));
+    bzero(&so_mask, sizeof(so_mask));
+    bzero(&rtm, sizeof(struct rt_msghdr));
+
+    rtm.rtm_type = RTM_GET;
+    rtm.rtm_flags = RTF_UP;
+    rtm.rtm_version = RTM_VERSION;
+    rtm.rtm_seq = ++seq;
+#ifdef TARGET_OPENBSD
+    rtm.rtm_tableid = getrtable();
+#endif
+
+    so_dst.sin6_family = AF_INET6;
+    so_mask.sin6_family = AF_INET6;
+
+    if (dest != NULL                    /* specific host? */
+        && !IN6_IS_ADDR_UNSPECIFIED(dest) )
+    {
+        so_dst.sin6_addr = *dest;
+        /* :: needs /0 "netmask", host route wants "no netmask */
+        rtm_addrs &= ~RTA_NETMASK;
+    }
+
+    rtm.rtm_addrs = rtm_addrs;
+
+#ifndef TARGET_SOLARIS
+    so_dst.sin6_len = sizeof(struct sockaddr_in6);
+    so_mask.sin6_len = sizeof(struct sockaddr_in6);
+#endif
+
+    NEXTADDR(RTA_DST, so_dst);
+    NEXTADDR(RTA_NETMASK, so_mask);
+
+    rtm.rtm_msglen = l = cp - (char *)&m_rtmsg;
+
+    /* transact with routing socket */
+    sockfd = socket(PF_ROUTE, SOCK_RAW, 0);
+    if (sockfd < 0)
+    {
+        msg(M_WARN, "GDG6: socket #1 failed");
+        goto done;
+    }
+    if (write(sockfd, (char *)&m_rtmsg, l) < 0)
+    {
+        msg(M_WARN, "GDG6: problem writing to routing socket");
+        goto done;
+    }
+
+    do
+    {
+        l = read(sockfd, (char *)&m_rtmsg, sizeof(m_rtmsg));
+    }
+    while (l > 0 && (rtm.rtm_seq != seq || rtm.rtm_pid != pid));
+
+    close(sockfd);
+    sockfd = -1;
+
+    /* extract return data from routing socket */
+    rtm_aux = &rtm;
+    cp = ((char *)(rtm_aux + 1));
+    if (rtm_aux->rtm_addrs)
+    {
+        for (i = 1; i; i <<= 1)
+        {
+            if (i & rtm_aux->rtm_addrs)
+            {
+                sa = (struct sockaddr *)cp;
+                if (i == RTA_GATEWAY)
+                {
+                    gate = sa;
+                }
+                else if (i == RTA_IFP)
+                {
+                    ifp = sa;
+                }
+                ADVANCE(cp, sa);
+            }
+        }
+    }
+    else
+    {
+        goto done;
+    }
+
+    /* get gateway addr and interface name */
+    if (gate != NULL)
+    {
+        struct sockaddr_in6 *s6 = (struct sockaddr_in6 *)gate;
+        struct in6_addr gw = s6->sin6_addr;
+
+#ifndef TARGET_SOLARIS
+        /* You do not really want to know... from FreeBSD's route.c
+         * (KAME encodes the 16 bit scope_id in s6_addr[2] + [3],
+         * but for a correct link-local address these must be :0000: )
+         */
+        if (gate->sa_len == sizeof(struct sockaddr_in6)
+            && IN6_IS_ADDR_LINKLOCAL(&gw) )
+        {
+            gw.s6_addr[2] = gw.s6_addr[3] = 0;
+        }
+
+        if (gate->sa_len != sizeof(struct sockaddr_in6)
+            || IN6_IS_ADDR_UNSPECIFIED(&gw) )
+        {
+            rgi6->flags |= RGI_ON_LINK;
+        }
+        else
+#endif
+
+        rgi6->gateway.addr_ipv6 = gw;
+        rgi6->flags |= RGI_ADDR_DEFINED;
+
+        if (ifp)
+        {
+            /* get interface name */
+            const struct sockaddr_dl *adl = (struct sockaddr_dl *) ifp;
+            if (adl->sdl_nlen && adl->sdl_nlen < sizeof(rgi6->iface))
+            {
+                memcpy(rgi6->iface, adl->sdl_data, adl->sdl_nlen);
+                rgi6->flags |= RGI_IFACE_DEFINED;
+            }
+        }
+    }
+
+done:
+    if (sockfd >= 0)
+    {
+        close(sockfd);
+    }
+}
+
+#undef max
+
+#else  /* if defined(_WIN32) */
+
+/*
+ * This is a platform-specific method that returns data about
+ * the current default gateway.  Return data is placed into
+ * a struct route_gateway_info object provided by caller.  The
+ * implementation should CLEAR the structure before adding
+ * data to it.
+ *
+ * Data returned includes:
+ * 1. default gateway address (rgi->gateway.addr)
+ * 2. netmask of interface that owns default gateway
+ *    (rgi->gateway.netmask)
+ * 3. hardware address (i.e. MAC address) of interface that owns
+ *    default gateway (rgi->hwaddr)
+ * 4. interface name (or adapter index on Windows) that owns default
+ *    gateway (rgi->iface or rgi->adapter_index)
+ * 5. an array of additional address/netmask pairs defined by
+ *    interface that owns default gateway (rgi->addrs with length
+ *    given in rgi->n_addrs)
+ *
+ * The flags RGI_x_DEFINED may be used to indicate which of the data
+ * members were successfully returned (set in rgi->flags).  All of
+ * the data members are optional, however certain OpenVPN functionality
+ * may be disabled by missing items.
+ */
+void
+get_default_gateway(struct route_gateway_info *rgi)
+{
+    CLEAR(*rgi);
+}
+void
+get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi6,
+                         const struct in6_addr *dest)
+{
+    msg(D_ROUTE, "no support for get_default_gateway_ipv6() on this system");
+    CLEAR(*rgi6);
+}
+
+#endif /* if defined(_WIN32) */
+
+bool
+netmask_to_netbits(const in_addr_t network, const in_addr_t netmask, int *netbits)
+{
+    int i;
+    const int addrlen = sizeof(in_addr_t) * 8;
+
+    if ((network & netmask) == network)
+    {
+        for (i = 0; i <= addrlen; ++i)
+        {
+            in_addr_t mask = netbits_to_netmask(i);
+            if (mask == netmask)
+            {
+                if (i == addrlen)
+                {
+                    *netbits = -1;
+                }
+                else
+                {
+                    *netbits = i;
+                }
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+/* similar to netmask_to_netbits(), but don't mess with base address
+ * etc., just convert to netbits - non-mappable masks are returned as "-1"
+ */
+int
+netmask_to_netbits2(in_addr_t netmask)
+{
+    int i;
+    const int addrlen = sizeof(in_addr_t) * 8;
+
+    for (i = 0; i <= addrlen; ++i)
+    {
+        in_addr_t mask = netbits_to_netmask(i);
+        if (mask == netmask)
+        {
+            return i;
+        }
+    }
+    return -1;
+}
+
+
+/*
+ * get_bypass_addresses() is used by the redirect-gateway bypass-x
+ * functions to build a route bypass to selected DHCP/DNS servers,
+ * so that outgoing packets to these servers don't end up in the tunnel.
+ */
+
+#if defined(_WIN32)
+
+static void
+add_host_route_if_nonlocal(struct route_bypass *rb, const in_addr_t addr)
+{
+    if (test_local_addr(addr, NULL) == TLA_NONLOCAL && addr != 0 && addr != IPV4_NETMASK_HOST)
+    {
+        add_bypass_address(rb, addr);
+    }
+}
+
+static void
+add_host_route_array(struct route_bypass *rb, const IP_ADDR_STRING *iplist)
+{
+    while (iplist)
+    {
+        bool succeed = false;
+        const in_addr_t ip = getaddr(GETADDR_HOST_ORDER, iplist->IpAddress.String, 0, &succeed, NULL);
+        if (succeed)
+        {
+            add_host_route_if_nonlocal(rb, ip);
+        }
+        iplist = iplist->Next;
+    }
+}
+
+static void
+get_bypass_addresses(struct route_bypass *rb, const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    /*bool ret_bool = false;*/
+
+    /* get full routing table */
+    const MIB_IPFORWARDTABLE *routes = get_windows_routing_table(&gc);
+
+    /* get the route which represents the default gateway */
+    const MIB_IPFORWARDROW *row = get_default_gateway_row(routes);
+
+    if (row)
+    {
+        /* get the adapter which the default gateway is associated with */
+        const IP_ADAPTER_INFO *dgi = get_adapter_info(row->dwForwardIfIndex, &gc);
+
+        /* get extra adapter info, such as DNS addresses */
+        const IP_PER_ADAPTER_INFO *pai = get_per_adapter_info(row->dwForwardIfIndex, &gc);
+
+        /* Bypass DHCP server address */
+        if ((flags & RG_BYPASS_DHCP) && dgi && dgi->DhcpEnabled)
+        {
+            add_host_route_array(rb, &dgi->DhcpServer);
+        }
+
+        /* Bypass DNS server addresses */
+        if ((flags & RG_BYPASS_DNS) && pai)
+        {
+            add_host_route_array(rb, &pai->DnsServerList);
+        }
+    }
+
+    gc_free(&gc);
+}
+
+#else  /* if defined(_WIN32) */
+
+static void
+get_bypass_addresses(struct route_bypass *rb, const unsigned int flags)   /* PLATFORM-SPECIFIC */
+{
+}
+
+#endif /* if defined(_WIN32) */
+
+/*
+ * Test if addr is reachable via a local interface (return ILA_LOCAL),
+ * or if it needs to be routed via the default gateway (return
+ * ILA_NONLOCAL).  If the target platform doesn't implement this
+ * function, return ILA_NOT_IMPLEMENTED.
+ *
+ * Used by redirect-gateway autolocal feature
+ */
+
+#if defined(_WIN32)
+
+int
+test_local_addr(const in_addr_t addr, const struct route_gateway_info *rgi)
+{
+    struct gc_arena gc = gc_new();
+    const in_addr_t nonlocal_netmask = 0x80000000L; /* routes with netmask <= to this are considered non-local */
+    int ret = TLA_NONLOCAL;
+
+    /* get full routing table */
+    const MIB_IPFORWARDTABLE *rt = get_windows_routing_table(&gc);
+    if (rt)
+    {
+        int i;
+        for (i = 0; i < rt->dwNumEntries; ++i)
+        {
+            const MIB_IPFORWARDROW *row = &rt->table[i];
+            const in_addr_t net = ntohl(row->dwForwardDest);
+            const in_addr_t mask = ntohl(row->dwForwardMask);
+            if (mask > nonlocal_netmask && (addr & mask) == net)
+            {
+                ret = TLA_LOCAL;
+                break;
+            }
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+#else  /* if defined(_WIN32) */
+
+int
+test_local_addr(const in_addr_t addr, const struct route_gateway_info *rgi)  /* PLATFORM-SPECIFIC */
+{
+    if (rgi)
+    {
+        if (local_route(addr, 0xFFFFFFFF, rgi->gateway.addr, rgi))
+        {
+            return TLA_LOCAL;
+        }
+        else
+        {
+            return TLA_NONLOCAL;
+        }
+    }
+    return TLA_NOT_IMPLEMENTED;
+}
+
+#endif /* if defined(_WIN32) */
diff --git a/src/openvpn/route.h b/src/openvpn/route.h
new file mode 100644
index 0000000..6942022
--- /dev/null
+++ b/src/openvpn/route.h
@@ -0,0 +1,399 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Support routines for adding/deleting network routes.
+ */
+
+#ifndef ROUTE_H
+#define ROUTE_H
+
+#include "basic.h"
+#include "tun.h"
+#include "misc.h"
+
+#ifdef _WIN32
+/*
+ * Windows route methods
+ */
+#define ROUTE_METHOD_ADAPTIVE  0  /* try IP helper first then route.exe */
+#define ROUTE_METHOD_IPAPI     1  /* use IP helper API */
+#define ROUTE_METHOD_EXE       2  /* use route.exe */
+#define ROUTE_METHOD_SERVICE   3  /* use the privileged Windows service */
+#define ROUTE_METHOD_MASK      3
+#endif
+
+/*
+ * Route add/delete flags (must stay clear of ROUTE_METHOD bits)
+ */
+#define ROUTE_DELETE_FIRST  (1<<2)
+#define ROUTE_REF_GW        (1<<3)
+
+struct route_bypass
+{
+#define N_ROUTE_BYPASS 8
+    int n_bypass;
+    in_addr_t bypass[N_ROUTE_BYPASS];
+};
+
+struct route_special_addr
+{
+    /* bits indicating which members below are defined */
+#define RTSA_REMOTE_ENDPOINT  (1<<0)
+#define RTSA_REMOTE_HOST      (1<<1)
+#define RTSA_DEFAULT_METRIC   (1<<2)
+    unsigned int flags;
+
+    in_addr_t remote_endpoint;
+    in_addr_t remote_host;
+    int remote_host_local; /* TLA_x value */
+    struct route_bypass bypass;
+    int default_metric;
+};
+
+struct route_option {
+    struct route_option *next;
+    const char *network;
+    const char *netmask;
+    const char *gateway;
+    const char *metric;
+};
+
+/* redirect-gateway flags */
+#define RG_ENABLE         (1<<0)
+#define RG_LOCAL          (1<<1)
+#define RG_DEF1           (1<<2)
+#define RG_BYPASS_DHCP    (1<<3)
+#define RG_BYPASS_DNS     (1<<4)
+#define RG_REROUTE_GW     (1<<5)
+#define RG_AUTO_LOCAL     (1<<6)
+#define RG_BLOCK_LOCAL    (1<<7)
+
+struct route_option_list {
+    unsigned int flags; /* RG_x flags */
+    struct route_option *routes;
+    struct gc_arena *gc;
+};
+
+struct route_ipv6_option {
+    struct route_ipv6_option *next;
+    const char *prefix;         /* e.g. "2001:db8:1::/64" */
+    const char *gateway;        /* e.g. "2001:db8:0::2" */
+    const char *metric;         /* e.g. "5" */
+};
+
+struct route_ipv6_option_list {
+    unsigned int flags;         /* RG_x flags, see route_option-list */
+    struct route_ipv6_option *routes_ipv6;
+    struct gc_arena *gc;
+};
+
+struct route_ipv4 {
+#define RT_DEFINED        (1<<0)
+#define RT_ADDED          (1<<1)
+#define RT_METRIC_DEFINED (1<<2)
+    struct route_ipv4 *next;
+    unsigned int flags;
+    const struct route_option *option;
+    in_addr_t network;
+    in_addr_t netmask;
+    in_addr_t gateway;
+    int metric;
+};
+
+struct route_ipv6 {
+    struct route_ipv6 *next;
+    unsigned int flags;                         /* RT_ flags, see route_ipv4 */
+    struct in6_addr network;
+    unsigned int netbits;
+    struct in6_addr gateway;
+    int metric;
+    /* gateway interface */
+#ifdef _WIN32
+    DWORD adapter_index;        /* interface or ~0 if undefined */
+#else
+    char *iface;                /* interface name (null terminated) */
+#endif
+};
+
+
+struct route_gateway_address {
+    in_addr_t addr;
+    in_addr_t netmask;
+};
+
+struct route_gateway_info {
+#define RGI_ADDR_DEFINED     (1<<0)  /* set if gateway.addr defined */
+#define RGI_NETMASK_DEFINED  (1<<1)  /* set if gateway.netmask defined */
+#define RGI_HWADDR_DEFINED   (1<<2)  /* set if hwaddr is defined */
+#define RGI_IFACE_DEFINED    (1<<3)  /* set if iface is defined */
+#define RGI_OVERFLOW         (1<<4)  /* set if more interface addresses than will fit in addrs */
+#define RGI_ON_LINK          (1<<5)
+    unsigned int flags;
+
+    /* gateway interface */
+#ifdef _WIN32
+    DWORD adapter_index; /* interface or ~0 if undefined */
+#else
+    char iface[16]; /* interface name (null terminated), may be empty */
+#endif
+
+    /* gateway interface hardware address */
+    uint8_t hwaddr[6];
+
+    /* gateway/router address */
+    struct route_gateway_address gateway;
+
+    /* address/netmask pairs bound to interface */
+#define RGI_N_ADDRESSES 8
+    int n_addrs; /* len of addrs, may be 0 */
+    struct route_gateway_address addrs[RGI_N_ADDRESSES]; /* local addresses attached to iface */
+};
+
+struct route_ipv6_gateway_address {
+    struct in6_addr addr_ipv6;
+    int netbits_ipv6;
+};
+
+struct route_ipv6_gateway_info {
+/* RGI_ flags used as in route_gateway_info */
+    unsigned int flags;
+
+    /* gateway interface */
+#ifdef _WIN32
+    DWORD adapter_index; /* interface or ~0 if undefined */
+#else
+    char iface[16]; /* interface name (null terminated), may be empty */
+#endif
+
+    /* gateway interface hardware address */
+    uint8_t hwaddr[6];
+
+    /* gateway/router address */
+    struct route_ipv6_gateway_address gateway;
+
+    /* address/netmask pairs bound to interface */
+#define RGI_N_ADDRESSES 8
+    int n_addrs; /* len of addrs, may be 0 */
+    struct route_ipv6_gateway_address addrs[RGI_N_ADDRESSES]; /* local addresses attached to iface */
+};
+
+struct route_list {
+#define RL_DID_REDIRECT_DEFAULT_GATEWAY (1<<0)
+#define RL_DID_LOCAL                    (1<<1)
+#define RL_ROUTES_ADDED                 (1<<2)
+    unsigned int iflags;
+
+    struct route_special_addr spec;
+    struct route_gateway_info rgi;
+    unsigned int flags;   /* RG_x flags */
+    struct route_ipv4 *routes;
+    struct gc_arena gc;
+};
+
+struct route_ipv6_list {
+    unsigned int iflags;                /* RL_ flags, see route_list */
+
+    unsigned int spec_flags;            /* RTSA_ flags, route_special_addr */
+    struct in6_addr remote_endpoint_ipv6; /* inside tun */
+    struct in6_addr remote_host_ipv6;   /* --remote address */
+    int default_metric;
+
+    struct route_ipv6_gateway_info rgi6;
+    unsigned int flags;                 /* RG_x flags, see route_option_list */
+    struct route_ipv6 *routes_ipv6;
+    struct gc_arena gc;
+};
+
+#if P2MP
+/* internal OpenVPN route */
+struct iroute {
+    in_addr_t network;
+    int netbits;
+    struct iroute *next;
+};
+
+struct iroute_ipv6 {
+    struct in6_addr network;
+    unsigned int netbits;
+    struct iroute_ipv6 *next;
+};
+#endif
+
+struct route_option_list *new_route_option_list(struct gc_arena *a);
+
+struct route_ipv6_option_list *new_route_ipv6_option_list(struct gc_arena *a);
+
+struct route_option_list *clone_route_option_list(const struct route_option_list *src, struct gc_arena *a);
+
+struct route_ipv6_option_list *clone_route_ipv6_option_list(const struct route_ipv6_option_list *src, struct gc_arena *a);
+
+void copy_route_option_list(struct route_option_list *dest, const struct route_option_list *src, struct gc_arena *a);
+
+void copy_route_ipv6_option_list(struct route_ipv6_option_list *dest,
+                                 const struct route_ipv6_option_list *src,
+                                 struct gc_arena *a);
+
+void route_ipv6_clear_host_bits( struct route_ipv6 *r6 );
+
+void add_route_ipv6(struct route_ipv6 *r, const struct tuntap *tt, unsigned int flags, const struct env_set *es);
+
+void delete_route_ipv6(const struct route_ipv6 *r, const struct tuntap *tt, unsigned int flags, const struct env_set *es);
+
+void add_route(struct route_ipv4 *r,
+               const struct tuntap *tt,
+               unsigned int flags,
+               const struct route_gateway_info *rgi,
+               const struct env_set *es);
+
+void add_route_to_option_list(struct route_option_list *l,
+                              const char *network,
+                              const char *netmask,
+                              const char *gateway,
+                              const char *metric);
+
+void add_route_ipv6_to_option_list(struct route_ipv6_option_list *l,
+                                   const char *prefix,
+                                   const char *gateway,
+                                   const char *metric);
+
+bool init_route_list(struct route_list *rl,
+                     const struct route_option_list *opt,
+                     const char *remote_endpoint,
+                     int default_metric,
+                     in_addr_t remote_host,
+                     struct env_set *es);
+
+bool init_route_ipv6_list(struct route_ipv6_list *rl6,
+                          const struct route_ipv6_option_list *opt6,
+                          const char *remote_endpoint,
+                          int default_metric,
+                          const struct in6_addr *remote_host,
+                          struct env_set *es);
+
+void route_list_add_vpn_gateway(struct route_list *rl,
+                                struct env_set *es,
+                                const in_addr_t addr);
+
+void add_routes(struct route_list *rl,
+                struct route_ipv6_list *rl6,
+                const struct tuntap *tt,
+                unsigned int flags,
+                const struct env_set *es);
+
+void delete_routes(struct route_list *rl,
+                   struct route_ipv6_list *rl6,
+                   const struct tuntap *tt,
+                   unsigned int flags,
+                   const struct env_set *es);
+
+void setenv_routes(struct env_set *es, const struct route_list *rl);
+
+void setenv_routes_ipv6(struct env_set *es, const struct route_ipv6_list *rl6);
+
+
+
+bool is_special_addr(const char *addr_str);
+
+void get_default_gateway(struct route_gateway_info *rgi);
+
+void get_default_gateway_ipv6(struct route_ipv6_gateway_info *rgi,
+                              const struct in6_addr *dest);
+
+void print_default_gateway(const int msglevel,
+                           const struct route_gateway_info *rgi,
+                           const struct route_ipv6_gateway_info *rgi6);
+
+/*
+ * Test if addr is reachable via a local interface (return ILA_LOCAL),
+ * or if it needs to be routed via the default gateway (return
+ * ILA_NONLOCAL).  If the current platform doesn't implement this
+ * function, return ILA_NOT_IMPLEMENTED.
+ */
+#define TLA_NOT_IMPLEMENTED 0
+#define TLA_NONLOCAL        1
+#define TLA_LOCAL           2
+int test_local_addr(const in_addr_t addr, const struct route_gateway_info *rgi);
+
+#ifndef ENABLE_SMALL
+void print_route_options(const struct route_option_list *rol,
+                         int level);
+
+#endif
+
+void print_routes(const struct route_list *rl, int level);
+
+#ifdef _WIN32
+
+void show_routes(int msglev);
+
+bool test_routes(const struct route_list *rl, const struct tuntap *tt);
+
+bool add_route_ipapi(const struct route_ipv4 *r, const struct tuntap *tt, DWORD adapter_index);
+
+bool del_route_ipapi(const struct route_ipv4 *r, const struct tuntap *tt);
+
+#else  /* ifdef _WIN32 */
+static inline bool
+test_routes(const struct route_list *rl, const struct tuntap *tt)
+{
+    return true;
+}
+#endif
+
+bool netmask_to_netbits(const in_addr_t network, const in_addr_t netmask, int *netbits);
+
+int netmask_to_netbits2(in_addr_t netmask);
+
+static inline in_addr_t
+netbits_to_netmask(const int netbits)
+{
+    const int addrlen = sizeof(in_addr_t) * 8;
+    in_addr_t mask = 0;
+    if (netbits > 0 && netbits <= addrlen)
+    {
+        mask = IPV4_NETMASK_HOST << (addrlen-netbits);
+    }
+    return mask;
+}
+
+static inline bool
+route_list_vpn_gateway_needed(const struct route_list *rl)
+{
+    if (!rl)
+    {
+        return false;
+    }
+    else
+    {
+        return !(rl->spec.flags & RTSA_REMOTE_ENDPOINT);
+    }
+}
+
+static inline int
+route_did_redirect_default_gateway(const struct route_list *rl)
+{
+    return rl && BOOL_CAST(rl->iflags & RL_DID_REDIRECT_DEFAULT_GATEWAY);
+}
+
+#endif /* ifndef ROUTE_H */
diff --git a/src/openvpn/schedule.c b/src/openvpn/schedule.c
new file mode 100644
index 0000000..76cf7c3
--- /dev/null
+++ b/src/openvpn/schedule.c
@@ -0,0 +1,726 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if P2MP_SERVER
+
+#include "buffer.h"
+#include "misc.h"
+#include "crypto.h"
+#include "schedule.h"
+
+#include "memdbg.h"
+
+#ifdef SCHEDULE_TEST
+
+struct status
+{
+    int sru;
+    int ins;
+    int coll;
+    int lsteps;
+};
+
+static struct status z;
+
+#endif
+
+#ifdef ENABLE_DEBUG
+static void
+schedule_entry_debug_info(const char *caller, const struct schedule_entry *e)
+{
+    struct gc_arena gc = gc_new();
+    if (e)
+    {
+        dmsg(D_SCHEDULER, "SCHEDULE: %s wakeup=[%s] pri=%u",
+             caller,
+             tv_string_abs(&e->tv, &gc),
+             e->pri);
+    }
+    else
+    {
+        dmsg(D_SCHEDULER, "SCHEDULE: %s NULL",
+             caller);
+    }
+    gc_free(&gc);
+}
+#endif
+
+static inline void
+schedule_set_pri(struct schedule_entry *e)
+{
+    e->pri = random();
+    if (e->pri < 1)
+    {
+        e->pri = 1;
+    }
+}
+
+/* This is the master key comparison routine.  A key is
+ * simply a struct timeval containing the absolute time for
+ * an event.  The unique treap priority (pri) is used to ensure
+ * that keys do not collide.
+ */
+static inline int
+schedule_entry_compare(const struct schedule_entry *e1,
+                       const struct schedule_entry *e2)
+{
+    if (e1->tv.tv_sec < e2->tv.tv_sec)
+    {
+        return -1;
+    }
+    else if (e1->tv.tv_sec > e2->tv.tv_sec)
+    {
+        return 1;
+    }
+    else
+    {
+        if (e1->tv.tv_usec < e2->tv.tv_usec)
+        {
+            return -1;
+        }
+        else if (e1->tv.tv_usec > e2->tv.tv_usec)
+        {
+            return 1;
+        }
+        else
+        {
+            if (e1->pri < e2->pri)
+            {
+                return -1;
+            }
+            else if (e1->pri > e2->pri)
+            {
+                return 1;
+            }
+            else
+            {
+                return 0;
+            }
+        }
+    }
+}
+
+/*
+ * Detach a btree node from its parent
+ */
+static inline void
+schedule_detach_parent(struct schedule *s, struct schedule_entry *e)
+{
+    if (e)
+    {
+        if (e->parent)
+        {
+            if (e->parent->lt == e)
+            {
+                e->parent->lt = NULL;
+            }
+            else if (e->parent->gt == e)
+            {
+                e->parent->gt = NULL;
+            }
+            else
+            {
+                /* parent <-> child linkage is corrupted */
+                ASSERT(0);
+            }
+            e->parent = NULL;
+        }
+        else
+        {
+            if (s->root == e) /* last element deleted, tree is empty */
+            {
+                s->root = NULL;
+            }
+        }
+    }
+}
+
+/*
+ *
+ * Given a binary search tree, move a node toward the root
+ * while still maintaining the correct ordering relationships
+ * within the tree.  This function is the workhorse
+ * of the tree balancer.
+ *
+ * This code will break on key collisions, which shouldn't
+ * happen because the treap priority is considered part of the key
+ * and is guaranteed to be unique.
+ */
+static void
+schedule_rotate_up(struct schedule *s, struct schedule_entry *e)
+{
+    if (e && e->parent)
+    {
+        struct schedule_entry *lt = e->lt;
+        struct schedule_entry *gt = e->gt;
+        struct schedule_entry *p = e->parent;
+        struct schedule_entry *gp = p->parent;
+
+        if (gp) /* if grandparent exists, modify its child link */
+        {
+            if (gp->gt == p)
+            {
+                gp->gt = e;
+            }
+            else if (gp->lt == p)
+            {
+                gp->lt = e;
+            }
+            else
+            {
+                ASSERT(0);
+            }
+        }
+        else /* no grandparent, now we are the root */
+        {
+            s->root = e;
+        }
+
+        /* grandparent is now our parent */
+        e->parent = gp;
+
+        /* parent is now our child */
+        p->parent = e;
+
+        /* reorient former parent's links
+         * to reflect new position in the tree */
+        if (p->gt == e)
+        {
+            e->lt = p;
+            p->gt = lt;
+            if (lt)
+            {
+                lt->parent = p;
+            }
+        }
+        else if (p->lt == e)
+        {
+            e->gt = p;
+            p->lt = gt;
+            if (gt)
+            {
+                gt->parent = p;
+            }
+        }
+        else
+        {
+            /* parent <-> child linkage is corrupted */
+            ASSERT(0);
+        }
+
+#ifdef SCHEDULE_TEST
+        ++z.sru;
+#endif
+    }
+}
+
+/*
+ * This is the treap deletion algorithm:
+ *
+ * Rotate lesser-priority children up in the tree
+ * until we are childless.  Then delete.
+ */
+void
+schedule_remove_node(struct schedule *s, struct schedule_entry *e)
+{
+    while (e->lt || e->gt)
+    {
+        if (e->lt)
+        {
+            if (e->gt)
+            {
+                if (e->lt->pri < e->gt->pri)
+                {
+                    schedule_rotate_up(s, e->lt);
+                }
+                else
+                {
+                    schedule_rotate_up(s, e->gt);
+                }
+            }
+            else
+            {
+                schedule_rotate_up(s, e->lt);
+            }
+        }
+        else if (e->gt)
+        {
+            schedule_rotate_up(s, e->gt);
+        }
+    }
+
+    schedule_detach_parent(s, e);
+    e->pri = 0;
+}
+
+/*
+ * Trivially add a node to a binary search tree without
+ * regard for balance.
+ */
+static void
+schedule_insert(struct schedule *s, struct schedule_entry *e)
+{
+    struct schedule_entry *c = s->root;
+    while (true)
+    {
+        const int comp = schedule_entry_compare(e, c);
+
+#ifdef SCHEDULE_TEST
+        ++z.ins;
+#endif
+
+        if (comp == -1)
+        {
+            if (c->lt)
+            {
+                c = c->lt;
+                continue;
+            }
+            else
+            {
+                c->lt = e;
+                e->parent = c;
+                break;
+            }
+        }
+        else if (comp == 1)
+        {
+            if (c->gt)
+            {
+                c = c->gt;
+                continue;
+            }
+            else
+            {
+                c->gt = e;
+                e->parent = c;
+                break;
+            }
+        }
+        else
+        {
+            /* rare key/priority collision -- no big deal,
+             * just choose another priority and retry */
+#ifdef SCHEDULE_TEST
+            ++z.coll;
+#endif
+            schedule_set_pri(e);
+            /* msg (M_INFO, "PRI COLLISION pri=%u", e->pri); */
+            c = s->root;
+            continue;
+        }
+    }
+}
+
+/*
+ * Given an element, remove it from the btree if it's already
+ * there and re-insert it based on its current key.
+ */
+void
+schedule_add_modify(struct schedule *s, struct schedule_entry *e)
+{
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_SCHEDULER))
+    {
+        schedule_entry_debug_info("schedule_add_modify", e);
+    }
+#endif
+
+    /* already in tree, remove */
+    if (IN_TREE(e))
+    {
+        schedule_remove_node(s, e);
+    }
+
+    /* set random priority */
+    schedule_set_pri(e);
+
+    if (s->root)
+    {
+        schedule_insert(s, e);   /* trivial insert into tree */
+    }
+    else
+    {
+        s->root = e; /* tree was empty, we are the first element */
+
+    }
+    /* This is the magic of the randomized treap algorithm which
+     * keeps the tree balanced.  Move the node up the tree until
+     * its own priority is greater than that of its parent */
+    while (e->parent && e->parent->pri > e->pri)
+    {
+        schedule_rotate_up(s, e);
+    }
+}
+
+/*
+ * Find the earliest event to be scheduled
+ */
+struct schedule_entry *
+schedule_find_least(struct schedule_entry *e)
+{
+    if (e)
+    {
+        while (e->lt)
+        {
+#ifdef SCHEDULE_TEST
+            ++z.lsteps;
+#endif
+            e = e->lt;
+        }
+    }
+
+#ifdef ENABLE_DEBUG
+    if (check_debug_level(D_SCHEDULER))
+    {
+        schedule_entry_debug_info("schedule_find_least", e);
+    }
+#endif
+
+    return e;
+}
+
+/*
+ *  Public functions below this point
+ */
+
+struct schedule *
+schedule_init(void)
+{
+    struct schedule *s;
+
+    ALLOC_OBJ_CLEAR(s, struct schedule);
+    return s;
+}
+
+void
+schedule_free(struct schedule *s)
+{
+    free(s);
+}
+
+void
+schedule_remove_entry(struct schedule *s, struct schedule_entry *e)
+{
+    s->earliest_wakeup = NULL; /* invalidate cache */
+    schedule_remove_node(s, e);
+}
+
+/*
+ *  Debug functions below this point
+ */
+
+#ifdef SCHEDULE_TEST
+
+static inline struct schedule_entry *
+schedule_find_earliest_wakeup(struct schedule *s)
+{
+    return schedule_find_least(s->root);
+}
+
+/*
+ * Recursively check that the treap (btree) is
+ * internally consistent.
+ */
+int
+schedule_debug_entry(const struct schedule_entry *e,
+                     int depth,
+                     int *count,
+                     struct timeval *least,
+                     const struct timeval *min,
+                     const struct timeval *max)
+{
+    struct gc_arena gc = gc_new();
+    int maxdepth = depth;
+    if (e)
+    {
+        int d;
+
+        ASSERT(e != e->lt);
+        ASSERT(e != e->gt);
+        ASSERT(e != e->parent);
+        ASSERT(!e->parent || e->parent != e->lt);
+        ASSERT(!e->parent || e->parent != e->gt);
+        ASSERT(!e->lt || e->lt != e->gt);
+
+        if (e->lt)
+        {
+            ASSERT(e->lt->parent == e);
+            ASSERT(schedule_entry_compare(e->lt, e) == -1);
+            ASSERT(e->lt->pri >= e->pri);
+        }
+
+        if (e->gt)
+        {
+            ASSERT(e->gt->parent == e);
+            ASSERT(schedule_entry_compare(e->gt, e));
+            ASSERT(e->gt->pri >= e->pri);
+        }
+
+        ASSERT(tv_le(min, &e->tv));
+        ASSERT(tv_le(&e->tv, max));
+
+        if (count)
+        {
+            ++(*count);
+        }
+
+        if (least && tv_lt(&e->tv, least))
+        {
+            *least = e->tv;
+        }
+
+        d = schedule_debug_entry(e->lt, depth+1, count, least, min, &e->tv);
+        if (d > maxdepth)
+        {
+            maxdepth = d;
+        }
+
+        d = schedule_debug_entry(e->gt, depth+1, count, least, &e->tv, max);
+        if (d > maxdepth)
+        {
+            maxdepth = d;
+        }
+    }
+    gc_free(&gc);
+    return maxdepth;
+}
+
+int
+schedule_debug(struct schedule *s, int *count, struct timeval *least)
+{
+    struct timeval min;
+    struct timeval max;
+
+    min.tv_sec = 0;
+    min.tv_usec = 0;
+    max.tv_sec = 0x7FFFFFFF;
+    max.tv_usec = 0x7FFFFFFF;
+
+    if (s->root)
+    {
+        ASSERT(s->root->parent == NULL);
+    }
+    return schedule_debug_entry(s->root, 0, count, least, &min, &max);
+}
+
+#if 1
+
+void
+tv_randomize(struct timeval *tv)
+{
+    tv->tv_sec += random() % 100;
+    tv->tv_usec = random() % 100;
+}
+
+#else  /* if 1 */
+
+void
+tv_randomize(struct timeval *tv)
+{
+    struct gc_arena gc = gc_new();
+    long int choice = get_random();
+    if ((choice & 0xFF) == 0)
+    {
+        tv->tv_usec += ((choice >> 8) & 0xFF);
+    }
+    else
+    {
+        prng_bytes((uint8_t *)tv, sizeof(struct timeval));
+    }
+    gc_free(&gc);
+}
+
+#endif /* if 1 */
+
+void
+schedule_verify(struct schedule *s)
+{
+    struct gc_arena gc = gc_new();
+    struct timeval least;
+    int count;
+    int maxlev;
+    struct schedule_entry *e;
+    const struct status zz = z;
+
+    least.tv_sec = least.tv_usec = 0x7FFFFFFF;
+
+    count = 0;
+
+    maxlev = schedule_debug(s, &count, &least);
+
+    e = schedule_find_earliest_wakeup(s);
+
+    if (e)
+    {
+        printf("Verification Phase  count=%d maxlev=%d sru=%d ins=%d coll=%d ls=%d l=%s",
+               count,
+               maxlev,
+               zz.sru,
+               zz.ins,
+               zz.coll,
+               zz.lsteps,
+               tv_string(&e->tv, &gc));
+
+        if (!tv_eq(&least, &e->tv))
+        {
+            printf(" [COMPUTED DIFFERENT MIN VALUES!]");
+        }
+
+        printf("\n");
+    }
+
+    CLEAR(z);
+    gc_free(&gc);
+}
+
+void
+schedule_randomize_array(struct schedule_entry **array, int size)
+{
+    int i;
+    for (i = 0; i < size; ++i)
+    {
+        const int src = get_random() % size;
+        struct schedule_entry *tmp = array [i];
+        if (i != src)
+        {
+            array [i] = array [src];
+            array [src] = tmp;
+        }
+    }
+}
+
+void
+schedule_print_work(struct schedule_entry *e, int indent)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    for (i = 0; i < indent; ++i)
+    {
+        printf(" ");
+    }
+    if (e)
+    {
+        printf("%s [%u] e=" ptr_format ", p=" ptr_format " lt=" ptr_format " gt=" ptr_format "\n",
+               tv_string(&e->tv, &gc),
+               e->pri,
+               (ptr_type)e,
+               (ptr_type)e->parent,
+               (ptr_type)e->lt,
+               (ptr_type)e->gt);
+        schedule_print_work(e->lt, indent+1);
+        schedule_print_work(e->gt, indent+1);
+    }
+    else
+    {
+        printf("NULL\n");
+    }
+    gc_free(&gc);
+}
+
+void
+schedule_print(struct schedule *s)
+{
+    printf("*************************\n");
+    schedule_print_work(s->root, 0);
+}
+
+void
+schedule_test(void)
+{
+    struct gc_arena gc = gc_new();
+    int n = 1000;
+    int n_mod = 25;
+
+    int i, j;
+    struct schedule_entry **array;
+    struct schedule *s = schedule_init();
+    struct schedule_entry *e;
+
+    CLEAR(z);
+    ALLOC_ARRAY(array, struct schedule_entry *, n);
+
+    printf("Creation/Insertion Phase\n");
+
+    for (i = 0; i < n; ++i)
+    {
+        ALLOC_OBJ_CLEAR(array[i], struct schedule_entry);
+        tv_randomize(&array[i]->tv);
+        /*schedule_print (s);*/
+        /*schedule_verify (s);*/
+        schedule_add_modify(s, array[i]);
+    }
+
+    schedule_randomize_array(array, n);
+
+    /*schedule_print (s);*/
+    schedule_verify(s);
+
+    for (j = 1; j <= n_mod; ++j)
+    {
+        printf("Modification Phase Pass %d\n", j);
+
+        for (i = 0; i < n; ++i)
+        {
+            e = schedule_find_earliest_wakeup(s);
+            /*printf ("BEFORE %s\n", tv_string (&e->tv, &gc));*/
+            tv_randomize(&e->tv);
+            /*printf ("AFTER %s\n", tv_string (&e->tv, &gc));*/
+            schedule_add_modify(s, e);
+            /*schedule_verify (s);*/
+            /*schedule_print (s);*/
+        }
+        schedule_verify(s);
+        /*schedule_print (s);*/
+    }
+
+    /*printf ("INS=%d\n", z.ins);*/
+
+    while ((e = schedule_find_earliest_wakeup(s)))
+    {
+        schedule_remove_node(s, e);
+        /*schedule_verify (s);*/
+    }
+    schedule_verify(s);
+
+    printf("S->ROOT is %s\n", s->root ? "NOT NULL" : "NULL");
+
+    for (i = 0; i < n; ++i)
+    {
+        free(array[i]);
+    }
+    free(array);
+    free(s);
+    gc_free(&gc);
+}
+
+#endif /* ifdef SCHEDULE_TEST */
+#endif /* if P2MP_SERVER */
diff --git a/src/openvpn/schedule.h b/src/openvpn/schedule.h
new file mode 100644
index 0000000..74d37fb
--- /dev/null
+++ b/src/openvpn/schedule.h
@@ -0,0 +1,140 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef SCHEDULE_H
+#define SCHEDULE_H
+
+/*
+ * This code implements an efficient scheduler using
+ * a random treap binary tree.
+ *
+ * The scheduler is used by the server executive to
+ * keep track of which instances need service at a
+ * known time in the future.  Instances need to
+ * schedule events for things such as sending
+ * a ping or scheduling a TLS renegotiation.
+ */
+
+#if P2MP_SERVER
+
+/* define to enable a special test mode */
+/*#define SCHEDULE_TEST*/
+
+#include "otime.h"
+#include "error.h"
+
+struct schedule_entry
+{
+    struct timeval tv;           /* wakeup time */
+    unsigned int pri;            /* random treap priority */
+    struct schedule_entry *parent; /* treap (btree) links */
+    struct schedule_entry *lt;
+    struct schedule_entry *gt;
+};
+
+struct schedule
+{
+    struct schedule_entry *earliest_wakeup; /* cached earliest wakeup */
+    struct schedule_entry *root;          /* the root of the treap (btree) */
+};
+
+/* Public functions */
+
+struct schedule *schedule_init(void);
+
+void schedule_free(struct schedule *s);
+
+void schedule_remove_entry(struct schedule *s, struct schedule_entry *e);
+
+#ifdef SCHEDULE_TEST
+void schedule_test(void);
+
+#endif
+
+/* Private Functions */
+
+/* is node already in tree? */
+#define IN_TREE(e) ((e)->pri)
+
+struct schedule_entry *schedule_find_least(struct schedule_entry *e);
+
+void schedule_add_modify(struct schedule *s, struct schedule_entry *e);
+
+void schedule_remove_node(struct schedule *s, struct schedule_entry *e);
+
+/* Public inline functions */
+
+/*
+ * Add a struct schedule_entry (whose storage is managed by
+ * caller) to the btree.  tv signifies the wakeup time for
+ * a future event.  sigma is a time interval measured
+ * in microseconds -- the event window being represented
+ * starts at (tv - sigma) and ends at (tv + sigma).
+ * Event signaling can occur anywere within this interval.
+ * Making the interval larger makes the scheduler more efficient,
+ * while making it smaller results in more precise scheduling.
+ * The caller should treat the passed struct schedule_entry as
+ * an opaque object.
+ */
+static inline void
+schedule_add_entry(struct schedule *s,
+                   struct schedule_entry *e,
+                   const struct timeval *tv,
+                   unsigned int sigma)
+{
+    if (!IN_TREE(e) || !sigma || !tv_within_sigma(tv, &e->tv, sigma))
+    {
+        e->tv = *tv;
+        schedule_add_modify(s, e);
+        s->earliest_wakeup = NULL; /* invalidate cache */
+    }
+}
+
+/*
+ * Return the node with the earliest wakeup time.  If two
+ * nodes have the exact same wakeup time, select based on
+ * the random priority assigned to each node (the priority
+ * is randomized every time an entry is re-added).
+ */
+static inline struct schedule_entry *
+schedule_get_earliest_wakeup(struct schedule *s,
+                             struct timeval *wakeup)
+{
+    struct schedule_entry *ret;
+
+    /* cache result */
+    if (!s->earliest_wakeup)
+    {
+        s->earliest_wakeup = schedule_find_least(s->root);
+    }
+    ret = s->earliest_wakeup;
+    if (ret)
+    {
+        *wakeup = ret->tv;
+    }
+
+    return ret;
+}
+
+#endif /* if P2MP_SERVER */
+#endif /* ifndef SCHEDULE_H */
diff --git a/src/openvpn/session_id.c b/src/openvpn/session_id.c
new file mode 100644
index 0000000..2b50feb
--- /dev/null
+++ b/src/openvpn/session_id.c
@@ -0,0 +1,69 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Each session is identified by a random 8-byte session identifier.
+ *
+ * For efficiency, the session id is only transmitted over the control
+ * channel (which only sees traffic occasionally when keys are being
+ * negotiated).  The data channel sees a smaller version of the session-id --
+ * it is called the key_id and is currently 2 bits long.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "error.h"
+#include "common.h"
+#include "crypto.h"
+#include "session_id.h"
+
+#include "memdbg.h"
+
+const struct session_id x_session_id_zero;
+
+void
+session_id_random(struct session_id *sid)
+{
+    prng_bytes(sid->id, SID_SIZE);
+}
+
+const char *
+session_id_print(const struct session_id *sid, struct gc_arena *gc)
+{
+    return format_hex(sid->id, SID_SIZE, 0, gc);
+}
+
+#else  /* ifdef ENABLE_CRYPTO */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/session_id.h b/src/openvpn/session_id.h
new file mode 100644
index 0000000..5e950a6
--- /dev/null
+++ b/src/openvpn/session_id.h
@@ -0,0 +1,85 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Each session is identified by a random 8-byte session identifier.
+ *
+ * For efficiency, the session id is only transmitted over the control
+ * channel (which only sees traffic occasionally when keys are being
+ * negotiated).
+ */
+
+#ifdef ENABLE_CRYPTO
+
+#ifndef SESSION_ID_H
+#define SESSION_ID_H
+
+#include "basic.h"
+#include "buffer.h"
+
+struct session_id
+{
+    uint8_t id[8];
+};
+
+extern const struct session_id x_session_id_zero;
+
+#define SID_SIZE (sizeof(x_session_id_zero.id))
+
+static inline bool
+session_id_equal(const struct session_id *sid1,
+                 const struct session_id *sid2)
+{
+    return !memcmp(sid1->id, sid2->id, SID_SIZE);
+}
+
+static inline bool
+session_id_defined(const struct session_id *sid1)
+{
+    return memcmp(sid1->id, &x_session_id_zero.id, SID_SIZE) != 0;
+}
+
+static inline bool
+session_id_read(struct session_id *sid, struct buffer *buf)
+{
+    return buf_read(buf, sid->id, SID_SIZE);
+}
+
+static inline bool
+session_id_write_prepend(const struct session_id *sid, struct buffer *buf)
+{
+    return buf_write_prepend(buf, sid->id, SID_SIZE);
+}
+
+static inline bool
+session_id_write(const struct session_id *sid, struct buffer *buf)
+{
+    return buf_write(buf, sid->id, SID_SIZE);
+}
+
+void session_id_random(struct session_id *sid);
+
+const char *session_id_print(const struct session_id *sid, struct gc_arena *gc);
+
+#endif /* SESSION_ID_H */
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/shaper.c b/src/openvpn/shaper.c
new file mode 100644
index 0000000..00eb2e9
--- /dev/null
+++ b/src/openvpn/shaper.c
@@ -0,0 +1,103 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "shaper.h"
+#include "memdbg.h"
+
+#ifdef ENABLE_FEATURE_SHAPER
+
+/*
+ * We want to wake up in delay microseconds.  If timeval is larger
+ * than delay, set timeval to delay.
+ */
+bool
+shaper_soonest_event(struct timeval *tv, int delay)
+{
+    bool ret = false;
+    if (delay < 1000000)
+    {
+        if (tv->tv_sec)
+        {
+            tv->tv_sec = 0;
+            tv->tv_usec = delay;
+            ret = true;
+        }
+        else if (delay < tv->tv_usec)
+        {
+            tv->tv_usec = delay;
+            ret = true;
+        }
+    }
+    else
+    {
+        const int sec = delay / 1000000;
+        const int usec = delay % 1000000;
+
+        if (sec < tv->tv_sec)
+        {
+            tv->tv_sec = sec;
+            tv->tv_usec = usec;
+            ret = true;
+        }
+        else if (sec == tv->tv_sec)
+        {
+            if (usec < tv->tv_usec)
+            {
+                tv->tv_usec = usec;
+                ret = true;
+            }
+        }
+    }
+#ifdef SHAPER_DEBUG
+    dmsg(D_SHAPER_DEBUG, "SHAPER shaper_soonest_event sec=%d usec=%d ret=%d",
+         (int)tv->tv_sec, (int)tv->tv_usec, (int)ret);
+#endif
+    return ret;
+}
+
+void
+shaper_reset_wakeup(struct shaper *s)
+{
+    CLEAR(s->wakeup);
+}
+
+void
+shaper_msg(struct shaper *s)
+{
+    msg(M_INFO, "Output Traffic Shaping initialized at %d bytes per second",
+        s->bytes_per_second);
+}
+
+#else  /* ifdef ENABLE_FEATURE_SHAPER */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_FEATURE_SHAPER */
diff --git a/src/openvpn/shaper.h b/src/openvpn/shaper.h
new file mode 100644
index 0000000..0496c71
--- /dev/null
+++ b/src/openvpn/shaper.h
@@ -0,0 +1,178 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef SHAPER_H
+#define SHAPER_H
+
+/*#define SHAPER_DEBUG*/
+
+#ifdef ENABLE_FEATURE_SHAPER
+
+#include "basic.h"
+#include "integer.h"
+#include "misc.h"
+#include "error.h"
+#include "interval.h"
+
+/*
+ * A simple traffic shaper for
+ * the output direction.
+ */
+
+#define SHAPER_MIN 100          /* bytes per second */
+#define SHAPER_MAX 100000000
+
+#define SHAPER_MAX_TIMEOUT 10   /* seconds */
+
+#define SHAPER_USE_FP
+
+struct shaper
+{
+    int bytes_per_second;
+    struct timeval wakeup;
+
+#ifdef SHAPER_USE_FP
+    double factor;
+#else
+    int factor;
+#endif
+};
+
+void shaper_msg(struct shaper *s);
+
+void shaper_reset_wakeup(struct shaper *s);
+
+/*
+ * We want to wake up in delay microseconds.  If timeval is larger
+ * than delay, set timeval to delay.
+ */
+bool shaper_soonest_event(struct timeval *tv, int delay);
+
+/*
+ * inline functions
+ */
+
+static inline void
+shaper_reset(struct shaper *s, int bytes_per_second)
+{
+    s->bytes_per_second = constrain_int(bytes_per_second, SHAPER_MIN, SHAPER_MAX);
+
+#ifdef SHAPER_USE_FP
+    s->factor = 1000000.0 / (double)s->bytes_per_second;
+#else
+    s->factor = 1000000 / s->bytes_per_second;
+#endif
+}
+
+static inline void
+shaper_init(struct shaper *s, int bytes_per_second)
+{
+    shaper_reset(s, bytes_per_second);
+    shaper_reset_wakeup(s);
+}
+
+static inline int
+shaper_current_bandwidth(struct shaper *s)
+{
+    return s->bytes_per_second;
+}
+
+/*
+ * Returns traffic shaping delay in microseconds relative to current
+ * time, or 0 if no delay.
+ */
+static inline int
+shaper_delay(struct shaper *s)
+{
+    struct timeval tv;
+    int delay = 0;
+
+    if (tv_defined(&s->wakeup))
+    {
+        ASSERT(!openvpn_gettimeofday(&tv, NULL));
+        delay = tv_subtract(&s->wakeup, &tv, SHAPER_MAX_TIMEOUT);
+#ifdef SHAPER_DEBUG
+        dmsg(D_SHAPER_DEBUG, "SHAPER shaper_delay delay=%d", delay);
+#endif
+    }
+
+    return delay > 0 ? delay : 0;
+}
+
+
+/*
+ * We are about to send a datagram of nbytes bytes.
+ *
+ * Compute when we can send another datagram,
+ * based on target throughput (s->bytes_per_second).
+ */
+static inline void
+shaper_wrote_bytes(struct shaper *s, int nbytes)
+{
+    struct timeval tv;
+
+    /* compute delay in microseconds */
+    tv.tv_sec = 0;
+#ifdef SHAPER_USE_FP
+    tv.tv_usec = min_int((int)((double)max_int(nbytes, 100) * s->factor), (SHAPER_MAX_TIMEOUT*1000000));
+#else
+    tv.tv_usec = s->bytes_per_second
+                 ? min_int(max_int(nbytes, 100) * s->factor, (SHAPER_MAX_TIMEOUT*1000000))
+                 : 0;
+#endif
+
+    if (tv.tv_usec)
+    {
+        ASSERT(!openvpn_gettimeofday(&s->wakeup, NULL));
+        tv_add(&s->wakeup, &tv);
+
+#ifdef SHAPER_DEBUG
+        dmsg(D_SHAPER_DEBUG, "SHAPER shaper_wrote_bytes bytes=%d delay=%d sec=%d usec=%d",
+             nbytes,
+             (int)tv.tv_usec,
+             (int)s->wakeup.tv_sec,
+             (int)s->wakeup.tv_usec);
+#endif
+    }
+}
+
+#if 0
+/*
+ * Increase/Decrease bandwidth by a percentage.
+ *
+ * Return true if bandwidth changed.
+ */
+static inline bool
+shaper_change_pct(struct shaper *s, int pct)
+{
+    const int orig_bandwidth = s->bytes_per_second;
+    const int new_bandwidth = orig_bandwidth + (orig_bandwidth * pct / 100);
+    ASSERT(s->bytes_per_second);
+    shaper_reset(s, new_bandwidth);
+    return s->bytes_per_second != orig_bandwidth;
+}
+#endif
+
+#endif /* ENABLE_FEATURE_SHAPER */
+
+#endif /* ifndef SHAPER_H */
diff --git a/src/openvpn/sig.c b/src/openvpn/sig.c
new file mode 100644
index 0000000..d7f2abb
--- /dev/null
+++ b/src/openvpn/sig.c
@@ -0,0 +1,467 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "buffer.h"
+#include "error.h"
+#include "win32.h"
+#include "init.h"
+#include "status.h"
+#include "sig.h"
+#include "occ.h"
+#include "manage.h"
+#include "openvpn.h"
+
+#include "memdbg.h"
+
+/* Handle signals */
+
+struct signal_info siginfo_static; /* GLOBAL */
+
+struct signame {
+    int value;
+    const char *upper;
+    const char *lower;
+};
+
+static const struct signame signames[] = {
+    { SIGINT,  "SIGINT",  "sigint"},
+    { SIGTERM, "SIGTERM", "sigterm" },
+    { SIGHUP,  "SIGHUP",  "sighup" },
+    { SIGUSR1, "SIGUSR1", "sigusr1" },
+    { SIGUSR2, "SIGUSR2", "sigusr2" }
+};
+
+int
+parse_signal(const char *signame)
+{
+    int i;
+    for (i = 0; i < (int)SIZE(signames); ++i)
+    {
+        if (!strcmp(signame, signames[i].upper))
+        {
+            return signames[i].value;
+        }
+    }
+    return -1;
+}
+
+const char *
+signal_name(const int sig, const bool upper)
+{
+    int i;
+    for (i = 0; i < (int)SIZE(signames); ++i)
+    {
+        if (sig == signames[i].value)
+        {
+            return upper ? signames[i].upper : signames[i].lower;
+        }
+    }
+    return "UNKNOWN";
+}
+
+const char *
+signal_description(const int signum, const char *sigtext)
+{
+    if (sigtext)
+    {
+        return sigtext;
+    }
+    else
+    {
+        return signal_name(signum, false);
+    }
+}
+
+void
+throw_signal(const int signum)
+{
+    siginfo_static.signal_received = signum;
+    siginfo_static.source = SIG_SOURCE_HARD;
+}
+
+void
+throw_signal_soft(const int signum, const char *signal_text)
+{
+    siginfo_static.signal_received = signum;
+    siginfo_static.source = SIG_SOURCE_SOFT;
+    siginfo_static.signal_text = signal_text;
+}
+
+static void
+signal_reset(struct signal_info *si)
+{
+    if (si)
+    {
+        si->signal_received = 0;
+        si->signal_text = NULL;
+        si->source = SIG_SOURCE_SOFT;
+    }
+}
+
+void
+print_signal(const struct signal_info *si, const char *title, int msglevel)
+{
+    if (si)
+    {
+        const char *type = (si->signal_text ? si->signal_text : "");
+        const char *t = (title ? title : "process");
+        const char *hs = NULL;
+        switch (si->source)
+        {
+            case SIG_SOURCE_SOFT:
+                hs = "soft";
+                break;
+
+            case SIG_SOURCE_HARD:
+                hs = "hard";
+                break;
+
+            case SIG_SOURCE_CONNECTION_FAILED:
+                hs = "connection failed(soft)";
+                break;
+
+            default:
+                ASSERT(0);
+        }
+
+        switch (si->signal_received)
+        {
+            case SIGINT:
+            case SIGTERM:
+                msg(msglevel, "%s[%s,%s] received, %s exiting",
+                    signal_name(si->signal_received, true), hs, type, t);
+                break;
+
+            case SIGHUP:
+            case SIGUSR1:
+                msg(msglevel, "%s[%s,%s] received, %s restarting",
+                    signal_name(si->signal_received, true), hs, type, t);
+                break;
+
+            default:
+                msg(msglevel, "Unknown signal %d [%s,%s] received by %s", si->signal_received, hs, type, t);
+                break;
+        }
+    }
+    else
+    {
+        msg(msglevel, "Unknown signal received");
+    }
+}
+
+/*
+ * Call management interface with restart info
+ */
+void
+signal_restart_status(const struct signal_info *si)
+{
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        int state = -1;
+        switch (si->signal_received)
+        {
+            case SIGINT:
+            case SIGTERM:
+                state = OPENVPN_STATE_EXITING;
+                break;
+
+            case SIGHUP:
+            case SIGUSR1:
+                state = OPENVPN_STATE_RECONNECTING;
+                break;
+        }
+
+        if (state >= 0)
+        {
+            management_set_state(management,
+                                 state,
+                                 si->signal_text ? si->signal_text : signal_name(si->signal_received, true),
+                                 NULL,
+                                 NULL,
+                                 NULL,
+                                 NULL);
+        }
+    }
+#endif /* ifdef ENABLE_MANAGEMENT */
+}
+
+#ifdef HAVE_SIGNAL_H
+
+/* normal signal handler, when we are in event loop */
+static void
+signal_handler(const int signum)
+{
+    throw_signal(signum);
+    signal(signum, signal_handler);
+}
+
+#endif
+
+/* set handlers for unix signals */
+
+#ifdef HAVE_SIGNAL_H
+#define SM_UNDEF     0
+#define SM_PRE_INIT  1
+#define SM_POST_INIT 2
+static int signal_mode; /* GLOBAL */
+#endif
+
+void
+pre_init_signal_catch(void)
+{
+#ifndef _WIN32
+#ifdef HAVE_SIGNAL_H
+    signal_mode = SM_PRE_INIT;
+    signal(SIGINT, signal_handler);
+    signal(SIGTERM, signal_handler);
+    signal(SIGHUP, SIG_IGN);
+    signal(SIGUSR1, SIG_IGN);
+    signal(SIGUSR2, SIG_IGN);
+    signal(SIGPIPE, SIG_IGN);
+#endif /* HAVE_SIGNAL_H */
+#endif /* _WIN32 */
+}
+
+void
+post_init_signal_catch(void)
+{
+#ifndef _WIN32
+#ifdef HAVE_SIGNAL_H
+    signal_mode = SM_POST_INIT;
+    signal(SIGINT, signal_handler);
+    signal(SIGTERM, signal_handler);
+    signal(SIGHUP, signal_handler);
+    signal(SIGUSR1, signal_handler);
+    signal(SIGUSR2, signal_handler);
+    signal(SIGPIPE, SIG_IGN);
+#endif /* HAVE_SIGNAL_H */
+#endif
+}
+
+/* called after daemonization to retain signal settings */
+void
+restore_signal_state(void)
+{
+#ifdef HAVE_SIGNAL_H
+    if (signal_mode == SM_PRE_INIT)
+    {
+        pre_init_signal_catch();
+    }
+    else if (signal_mode == SM_POST_INIT)
+    {
+        post_init_signal_catch();
+    }
+#endif
+}
+
+/*
+ * Print statistics.
+ *
+ * Triggered by SIGUSR2 or F2 on Windows.
+ */
+void
+print_status(const struct context *c, struct status_output *so)
+{
+    struct gc_arena gc = gc_new();
+
+    status_reset(so);
+
+    status_printf(so, "OpenVPN STATISTICS");
+    status_printf(so, "Updated,%s", time_string(0, 0, false, &gc));
+    status_printf(so, "TUN/TAP read bytes," counter_format, c->c2.tun_read_bytes);
+    status_printf(so, "TUN/TAP write bytes," counter_format, c->c2.tun_write_bytes);
+    status_printf(so, "TCP/UDP read bytes," counter_format, c->c2.link_read_bytes);
+    status_printf(so, "TCP/UDP write bytes," counter_format, c->c2.link_write_bytes);
+    status_printf(so, "Auth read bytes," counter_format, c->c2.link_read_bytes_auth);
+#ifdef USE_COMP
+    if (c->c2.comp_context)
+    {
+        comp_print_stats(c->c2.comp_context, so);
+    }
+#endif
+#ifdef PACKET_TRUNCATION_CHECK
+    status_printf(so, "TUN read truncations," counter_format, c->c2.n_trunc_tun_read);
+    status_printf(so, "TUN write truncations," counter_format, c->c2.n_trunc_tun_write);
+    status_printf(so, "Pre-encrypt truncations," counter_format, c->c2.n_trunc_pre_encrypt);
+    status_printf(so, "Post-decrypt truncations," counter_format, c->c2.n_trunc_post_decrypt);
+#endif
+#ifdef _WIN32
+    if (tuntap_defined(c->c1.tuntap))
+    {
+        status_printf(so, "TAP-WIN32 driver status,\"%s\"",
+                      tap_win_getinfo(c->c1.tuntap, &gc));
+    }
+#endif
+
+    status_printf(so, "END");
+    status_flush(so);
+    gc_free(&gc);
+}
+
+#ifdef ENABLE_OCC
+/*
+ * Handle the triggering and time-wait of explicit
+ * exit notification.
+ */
+
+static void
+process_explicit_exit_notification_init(struct context *c)
+{
+    msg(M_INFO, "SIGTERM received, sending exit notification to peer");
+    event_timeout_init(&c->c2.explicit_exit_notification_interval, 1, 0);
+    reset_coarse_timers(c);
+    signal_reset(c->sig);
+    halt_non_edge_triggered_signals();
+    c->c2.explicit_exit_notification_time_wait = now;
+}
+
+void
+process_explicit_exit_notification_timer_wakeup(struct context *c)
+{
+    if (event_timeout_trigger(&c->c2.explicit_exit_notification_interval,
+                              &c->c2.timeval,
+                              ETT_DEFAULT))
+    {
+        ASSERT(c->c2.explicit_exit_notification_time_wait && c->options.ce.explicit_exit_notification);
+        if (now >= c->c2.explicit_exit_notification_time_wait + c->options.ce.explicit_exit_notification)
+        {
+            event_timeout_clear(&c->c2.explicit_exit_notification_interval);
+            c->sig->signal_received = SIGTERM;
+            c->sig->signal_text = "exit-with-notification";
+        }
+        else
+        {
+            c->c2.occ_op = OCC_EXIT;
+        }
+    }
+}
+#endif /* ifdef ENABLE_OCC */
+
+/*
+ * Process signals
+ */
+
+void
+remap_signal(struct context *c)
+{
+    if (c->sig->signal_received == SIGUSR1 && c->options.remap_sigusr1)
+    {
+        c->sig->signal_received = c->options.remap_sigusr1;
+    }
+}
+
+static void
+process_sigusr2(const struct context *c)
+{
+    struct status_output *so = status_open(NULL, 0, M_INFO, NULL, 0);
+    print_status(c, so);
+    status_close(so);
+    signal_reset(c->sig);
+}
+
+static bool
+process_sigterm(struct context *c)
+{
+    bool ret = true;
+#ifdef ENABLE_OCC
+    if (c->options.ce.explicit_exit_notification
+        && !c->c2.explicit_exit_notification_time_wait)
+    {
+        process_explicit_exit_notification_init(c);
+        ret = false;
+    }
+#endif
+    return ret;
+}
+
+/**
+ * If a restart signal is received during exit-notification, reset the
+ * signal and return true. If its a soft restart signal from the event loop
+ * which implies the loop cannot continue, remap to SIGTERM to exit promptly.
+ */
+static bool
+ignore_restart_signals(struct context *c)
+{
+    bool ret = false;
+#ifdef ENABLE_OCC
+    if ( (c->sig->signal_received == SIGUSR1 || c->sig->signal_received == SIGHUP)
+         && event_timeout_defined(&c->c2.explicit_exit_notification_interval) )
+    {
+        if (c->sig->source == SIG_SOURCE_HARD)
+        {
+            msg(M_INFO, "Ignoring %s received during exit notification",
+                signal_name(c->sig->signal_received, true));
+            signal_reset(c->sig);
+            ret = true;
+        }
+        else
+        {
+            msg(M_INFO, "Converting soft %s received during exit notification to SIGTERM",
+                signal_name(c->sig->signal_received, true));
+            register_signal(c, SIGTERM, "exit-with-notification");
+            ret = false;
+        }
+    }
+#endif
+    return ret;
+}
+
+bool
+process_signal(struct context *c)
+{
+    bool ret = true;
+
+    if (ignore_restart_signals(c))
+    {
+        ret = false;
+    }
+    else if (c->sig->signal_received == SIGTERM || c->sig->signal_received == SIGINT)
+    {
+        ret = process_sigterm(c);
+    }
+    else if (c->sig->signal_received == SIGUSR2)
+    {
+        process_sigusr2(c);
+        ret = false;
+    }
+    return ret;
+}
+
+void
+register_signal(struct context *c, int sig, const char *text)
+{
+    if (c->sig->signal_received != SIGTERM)
+    {
+        c->sig->signal_received = sig;
+    }
+    c->sig->signal_text = text;
+}
diff --git a/src/openvpn/sig.h b/src/openvpn/sig.h
new file mode 100644
index 0000000..887d833
--- /dev/null
+++ b/src/openvpn/sig.h
@@ -0,0 +1,122 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef SIG_H
+#define SIG_H
+
+#include "status.h"
+#include "win32.h"
+
+
+
+#define SIG_SOURCE_SOFT 0
+#define SIG_SOURCE_HARD 1
+/* CONNECTION_FAILED is also a "soft" status,
+ * It is thrown if a connection attempt fails
+ */
+#define SIG_SOURCE_CONNECTION_FAILED 2
+
+/*
+ * Signal information, including signal code
+ * and descriptive text.
+ */
+struct signal_info
+{
+    volatile int signal_received;
+    volatile int source;
+    const char *signal_text;
+};
+
+#define IS_SIG(c) ((c)->sig->signal_received)
+
+struct context;
+
+extern struct signal_info siginfo_static;
+
+int parse_signal(const char *signame);
+
+const char *signal_name(const int sig, const bool upper);
+
+const char *signal_description(const int signum, const char *sigtext);
+
+void throw_signal(const int signum);
+
+void throw_signal_soft(const int signum, const char *signal_text);
+
+void pre_init_signal_catch(void);
+
+void post_init_signal_catch(void);
+
+void restore_signal_state(void);
+
+void print_signal(const struct signal_info *si, const char *title, int msglevel);
+
+void print_status(const struct context *c, struct status_output *so);
+
+void remap_signal(struct context *c);
+
+void signal_restart_status(const struct signal_info *si);
+
+bool process_signal(struct context *c);
+
+void register_signal(struct context *c, int sig, const char *text);
+
+#ifdef ENABLE_OCC
+void process_explicit_exit_notification_timer_wakeup(struct context *c);
+
+#endif
+
+#ifdef _WIN32
+
+static inline void
+get_signal(volatile int *sig)
+{
+    *sig = win32_signal_get(&win32_signal);
+}
+
+static inline void
+halt_non_edge_triggered_signals(void)
+{
+    win32_signal_close(&win32_signal);
+}
+
+#else  /* ifdef _WIN32 */
+
+static inline void
+get_signal(volatile int *sig)
+{
+    const int i = siginfo_static.signal_received;
+    if (i)
+    {
+        *sig = i;
+    }
+}
+
+static inline void
+halt_non_edge_triggered_signals(void)
+{
+}
+
+#endif /* ifdef _WIN32 */
+
+#endif /* ifndef SIG_H */
diff --git a/src/openvpn/socket.c b/src/openvpn/socket.c
new file mode 100644
index 0000000..9131ec2
--- /dev/null
+++ b/src/openvpn/socket.c
@@ -0,0 +1,4108 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "socket.h"
+#include "fdmisc.h"
+#include "misc.h"
+#include "gremlin.h"
+#include "plugin.h"
+#include "ps.h"
+#include "manage.h"
+#include "misc.h"
+#include "manage.h"
+#include "openvpn.h"
+#include "forward.h"
+
+#include "memdbg.h"
+
+const int proto_overhead[] = { /* indexed by PROTO_x */
+    0,
+    IPv4_UDP_HEADER_SIZE, /* IPv4 */
+    IPv4_TCP_HEADER_SIZE,
+    IPv4_TCP_HEADER_SIZE,
+    IPv6_UDP_HEADER_SIZE, /* IPv6 */
+    IPv6_TCP_HEADER_SIZE,
+    IPv6_TCP_HEADER_SIZE,
+    IPv6_TCP_HEADER_SIZE,
+};
+
+/*
+ * Convert sockflags/getaddr_flags into getaddr_flags
+ */
+static unsigned int
+sf2gaf(const unsigned int getaddr_flags,
+       const unsigned int sockflags)
+{
+    if (sockflags & SF_HOST_RANDOMIZE)
+    {
+        return getaddr_flags | GETADDR_RANDOMIZE;
+    }
+    else
+    {
+        return getaddr_flags;
+    }
+}
+
+/*
+ * Functions related to the translation of DNS names to IP addresses.
+ */
+static int
+get_addr_generic(sa_family_t af, unsigned int flags, const char *hostname,
+                 void *network, unsigned int *netbits,
+                 int resolve_retry_seconds, volatile int *signal_received,
+                 int msglevel)
+{
+    char *endp, *sep, *var_host = NULL;
+    struct addrinfo *ai = NULL;
+    unsigned long bits;
+    uint8_t max_bits;
+    int ret = -1;
+
+    if (!hostname)
+    {
+        msg(M_NONFATAL, "Can't resolve null hostname!");
+        goto out;
+    }
+
+    /* assign family specific default values */
+    switch (af)
+    {
+        case AF_INET:
+            bits = 0;
+            max_bits = sizeof(in_addr_t) * 8;
+            break;
+        case AF_INET6:
+            bits = 64;
+            max_bits = sizeof(struct in6_addr) * 8;
+            break;
+        default:
+            msg(M_WARN,
+                "Unsupported AF family passed to getaddrinfo for %s (%d)",
+                hostname, af);
+            goto out;
+    }
+
+    /* we need to modify the hostname received as input, but we don't want to
+     * touch it directly as it might be a constant string.
+     *
+     * Therefore, we clone the string here and free it at the end of the
+     * function */
+    var_host = strdup(hostname);
+    if (!var_host)
+    {
+        msg(M_NONFATAL | M_ERRNO,
+            "Can't allocate hostname buffer for getaddrinfo");
+        goto out;
+    }
+
+    /* check if this hostname has a /bits suffix */
+    sep = strchr(var_host , '/');
+    if (sep)
+    {
+        bits = strtoul(sep + 1, &endp, 10);
+        if ((*endp != '\0') || (bits > max_bits))
+        {
+            msg(msglevel, "IP prefix '%s': invalid '/bits' spec (%s)", hostname,
+                sep + 1);
+            goto out;
+        }
+        *sep = '\0';
+    }
+
+    ret = openvpn_getaddrinfo(flags & ~GETADDR_HOST_ORDER, var_host, NULL,
+                              resolve_retry_seconds, signal_received, af, &ai);
+    if ((ret == 0) && network)
+    {
+        struct in6_addr *ip6;
+        in_addr_t *ip4;
+
+        switch (af)
+        {
+            case AF_INET:
+                ip4 = network;
+                *ip4 = ((struct sockaddr_in *)ai->ai_addr)->sin_addr.s_addr;
+
+                if (flags & GETADDR_HOST_ORDER)
+                {
+                    *ip4 = ntohl(*ip4);
+                }
+                break;
+            case AF_INET6:
+                ip6 = network;
+                *ip6 = ((struct sockaddr_in6 *)ai->ai_addr)->sin6_addr;
+                break;
+            default:
+                /* can't get here because 'af' was previously checked */
+                msg(M_WARN,
+                    "Unsupported AF family for %s (%d)", var_host, af);
+                goto out;
+        }
+    }
+
+    if (netbits)
+    {
+        *netbits = bits;
+    }
+
+    /* restore '/' separator, if any */
+    if (sep)
+    {
+        *sep = '/';
+    }
+out:
+    freeaddrinfo(ai);
+    free(var_host);
+
+    return ret;
+}
+
+in_addr_t
+getaddr(unsigned int flags,
+        const char *hostname,
+        int resolve_retry_seconds,
+        bool *succeeded,
+        volatile int *signal_received)
+{
+    in_addr_t addr;
+    int status;
+
+    status = get_addr_generic(AF_INET, flags, hostname, &addr, NULL,
+                              resolve_retry_seconds, signal_received,
+                              M_WARN);
+    if (status==0)
+    {
+        if (succeeded)
+        {
+            *succeeded = true;
+        }
+        return addr;
+    }
+    else
+    {
+        if (succeeded)
+        {
+            *succeeded = false;
+        }
+        return 0;
+    }
+}
+
+bool
+get_ipv6_addr(const char *hostname, struct in6_addr *network,
+              unsigned int *netbits, int msglevel)
+{
+    if (get_addr_generic(AF_INET6, GETADDR_RESOLVE, hostname, network, netbits,
+                         0, NULL, msglevel) < 0)
+    {
+        return false;
+    }
+
+    return true;                /* parsing OK, values set */
+}
+
+static inline bool
+streqnull(const char *a, const char *b)
+{
+    if (a == NULL && b == NULL)
+    {
+        return true;
+    }
+    else if (a == NULL || b == NULL)
+    {
+        return false;
+    }
+    else
+    {
+        return streq(a, b);
+    }
+}
+
+/*
+ * get_cached_dns_entry return 0 on success and -1
+ * otherwise. (like getaddrinfo)
+ */
+static int
+get_cached_dns_entry(struct cached_dns_entry *dns_cache,
+                     const char *hostname,
+                     const char *servname,
+                     int ai_family,
+                     int resolve_flags,
+                     struct addrinfo **ai)
+{
+    struct cached_dns_entry *ph;
+    int flags;
+
+    /* Only use flags that are relevant for the structure */
+    flags = resolve_flags & GETADDR_CACHE_MASK;
+
+    for (ph = dns_cache; ph; ph = ph->next)
+    {
+        if (streqnull(ph->hostname, hostname)
+            && streqnull(ph->servname, servname)
+            && ph->ai_family == ai_family
+            && ph->flags == flags)
+        {
+            *ai = ph->ai;
+            return 0;
+        }
+    }
+    return -1;
+}
+
+
+static int
+do_preresolve_host(struct context *c,
+                   const char *hostname,
+                   const char *servname,
+                   const int af,
+                   const int flags)
+{
+    struct addrinfo *ai;
+    int status;
+
+    if (get_cached_dns_entry(c->c1.dns_cache,
+                             hostname,
+                             servname,
+                             af,
+                             flags,
+                             &ai) == 0)
+    {
+        /* entry already cached, return success */
+        return 0;
+    }
+
+    status = openvpn_getaddrinfo(flags, hostname, servname,
+                                 c->options.resolve_retry_seconds, NULL,
+                                 af, &ai);
+    if (status == 0)
+    {
+        struct cached_dns_entry *ph;
+
+        ALLOC_OBJ_CLEAR_GC(ph, struct cached_dns_entry, &c->gc);
+        ph->ai = ai;
+        ph->hostname = hostname;
+        ph->servname = servname;
+        ph->flags = flags & GETADDR_CACHE_MASK;
+
+        if (!c->c1.dns_cache)
+        {
+            c->c1.dns_cache = ph;
+        }
+        else
+        {
+            struct cached_dns_entry *prev = c->c1.dns_cache;
+            while (prev->next)
+            {
+                prev = prev->next;
+            }
+            prev->next = ph;
+        }
+
+        gc_addspecial(ai, &gc_freeaddrinfo_callback, &c->gc);
+
+    }
+    return status;
+}
+
+void
+do_preresolve(struct context *c)
+{
+    int i;
+    struct connection_list *l = c->options.connection_list;
+    const unsigned int preresolve_flags = GETADDR_RESOLVE
+                                          |GETADDR_UPDATE_MANAGEMENT_STATE
+                                          |GETADDR_MENTION_RESOLVE_RETRY
+                                          |GETADDR_FATAL;
+
+
+    for (i = 0; i < l->len; ++i)
+    {
+        int status;
+        const char *remote;
+        int flags = preresolve_flags;
+
+        struct connection_entry *ce = c->options.connection_list->array[i];
+
+        if (proto_is_dgram(ce->proto))
+        {
+            flags |= GETADDR_DATAGRAM;
+        }
+
+        if (c->options.sockflags & SF_HOST_RANDOMIZE)
+        {
+            flags |= GETADDR_RANDOMIZE;
+        }
+
+        if (c->options.ip_remote_hint)
+        {
+            remote = c->options.ip_remote_hint;
+        }
+        else
+        {
+            remote = ce->remote;
+        }
+
+        /* HTTP remote hostname does not need to be resolved */
+        if (!ce->http_proxy_options)
+        {
+            status = do_preresolve_host(c, remote, ce->remote_port, ce->af, flags);
+            if (status != 0)
+            {
+                goto err;
+            }
+        }
+
+        /* Preresolve proxy */
+        if (ce->http_proxy_options)
+        {
+            status = do_preresolve_host(c,
+                                        ce->http_proxy_options->server,
+                                        ce->http_proxy_options->port,
+                                        ce->af,
+                                        preresolve_flags);
+
+            if (status != 0)
+            {
+                goto err;
+            }
+        }
+
+        if (ce->socks_proxy_server)
+        {
+            status = do_preresolve_host(c,
+                                        ce->socks_proxy_server,
+                                        ce->socks_proxy_port,
+                                        ce->af,
+                                        flags);
+            if (status != 0)
+            {
+                goto err;
+            }
+        }
+
+        if (ce->bind_local)
+        {
+            flags |= GETADDR_PASSIVE;
+            flags &= ~GETADDR_RANDOMIZE;
+            status = do_preresolve_host(c, ce->local, ce->local_port, ce->af, flags);
+            if (status != 0)
+            {
+                goto err;
+            }
+
+        }
+
+    }
+    return;
+
+err:
+    throw_signal_soft(SIGHUP, "Preresolving failed");
+}
+
+/*
+ * Translate IPv4/IPv6 addr or hostname into struct addrinfo
+ * If resolve error, try again for resolve_retry_seconds seconds.
+ */
+int
+openvpn_getaddrinfo(unsigned int flags,
+                    const char *hostname,
+                    const char *servname,
+                    int resolve_retry_seconds,
+                    volatile int *signal_received,
+                    int ai_family,
+                    struct addrinfo **res)
+{
+    struct addrinfo hints;
+    int status;
+    int sigrec = 0;
+    int msglevel = (flags & GETADDR_FATAL) ? M_FATAL : D_RESOLVE_ERRORS;
+    struct gc_arena gc = gc_new();
+    const char *print_hostname;
+    const char *print_servname;
+
+    ASSERT(res);
+
+    ASSERT(hostname || servname);
+    ASSERT(!(flags & GETADDR_HOST_ORDER));
+
+    if (servname)
+    {
+        print_servname = servname;
+    }
+    else
+    {
+        print_servname = "";
+    }
+
+    if (flags & GETADDR_MSG_VIRT_OUT)
+    {
+        msglevel |= M_MSG_VIRT_OUT;
+    }
+
+    if ((flags & (GETADDR_FATAL_ON_SIGNAL|GETADDR_WARN_ON_SIGNAL))
+        && !signal_received)
+    {
+        signal_received = &sigrec;
+    }
+
+    /* try numeric ipv6 addr first */
+    CLEAR(hints);
+    hints.ai_family = ai_family;
+    hints.ai_flags = AI_NUMERICHOST;
+
+    if (flags & GETADDR_PASSIVE)
+    {
+        hints.ai_flags |= AI_PASSIVE;
+    }
+
+    if (flags & GETADDR_DATAGRAM)
+    {
+        hints.ai_socktype = SOCK_DGRAM;
+    }
+    else
+    {
+        hints.ai_socktype = SOCK_STREAM;
+    }
+
+    status = getaddrinfo(hostname, servname, &hints, res);
+
+    if (status != 0) /* parse as numeric address failed? */
+    {
+        const int fail_wait_interval = 5; /* seconds */
+        /* Add +4 to cause integer division rounding up (1 + 4) = 5, (0+4)/5=0 */
+        int resolve_retries = (flags & GETADDR_TRY_ONCE) ? 1 :
+                              ((resolve_retry_seconds + 4)/ fail_wait_interval);
+        const char *fmt;
+        int level = 0;
+
+        if (hostname && (flags & GETADDR_RANDOMIZE))
+        {
+            hostname = hostname_randomize(hostname, &gc);
+        }
+
+        if (hostname)
+        {
+            print_hostname = hostname;
+        }
+        else
+        {
+            print_hostname = "undefined";
+        }
+
+        fmt = "RESOLVE: Cannot resolve host address: %s:%s (%s)";
+        if ((flags & GETADDR_MENTION_RESOLVE_RETRY)
+            && !resolve_retry_seconds)
+        {
+            fmt = "RESOLVE: Cannot resolve host address: %s:%s (%s) (I would have retried this name query if you had specified the --resolv-retry option.)";
+        }
+
+        if (!(flags & GETADDR_RESOLVE) || status == EAI_FAIL)
+        {
+            msg(msglevel, "RESOLVE: Cannot parse IP address: %s:%s (%s)",
+                print_hostname,print_servname, gai_strerror(status));
+            goto done;
+        }
+
+#ifdef ENABLE_MANAGEMENT
+        if (flags & GETADDR_UPDATE_MANAGEMENT_STATE)
+        {
+            if (management)
+            {
+                management_set_state(management,
+                                     OPENVPN_STATE_RESOLVE,
+                                     NULL,
+                                     NULL,
+                                     NULL,
+                                     NULL,
+                                     NULL);
+            }
+        }
+#endif
+
+        /*
+         * Resolve hostname
+         */
+        while (true)
+        {
+#ifndef _WIN32
+            res_init();
+#endif
+            /* try hostname lookup */
+            hints.ai_flags &= ~AI_NUMERICHOST;
+            dmsg(D_SOCKET_DEBUG, "GETADDRINFO flags=0x%04x ai_family=%d ai_socktype=%d",
+                 flags, hints.ai_family, hints.ai_socktype);
+            status = getaddrinfo(hostname, servname, &hints, res);
+
+            if (signal_received)
+            {
+                get_signal(signal_received);
+                if (*signal_received) /* were we interrupted by a signal? */
+                {
+                    if (*signal_received == SIGUSR1) /* ignore SIGUSR1 */
+                    {
+                        msg(level, "RESOLVE: Ignored SIGUSR1 signal received during DNS resolution attempt");
+                        *signal_received = 0;
+                    }
+                    else
+                    {
+                        /* turn success into failure (interrupted syscall) */
+                        if (0 == status)
+                        {
+                            ASSERT(res);
+                            freeaddrinfo(*res);
+                            *res = NULL;
+                            status = EAI_AGAIN; /* = temporary failure */
+                            errno = EINTR;
+                        }
+                        goto done;
+                    }
+                }
+            }
+
+            /* success? */
+            if (0 == status)
+            {
+                break;
+            }
+
+            /* resolve lookup failed, should we
+             * continue or fail? */
+            level = msglevel;
+            if (resolve_retries > 0)
+            {
+                level = D_RESOLVE_ERRORS;
+            }
+
+            msg(level,
+                fmt,
+                print_hostname,
+                print_servname,
+                gai_strerror(status));
+
+            if (--resolve_retries <= 0)
+            {
+                goto done;
+            }
+
+            management_sleep(fail_wait_interval);
+        }
+
+        ASSERT(res);
+
+        /* hostname resolve succeeded */
+
+        /*
+         * Do not choose an IP Addresse by random or change the order *
+         * of IP addresses, doing so will break RFC 3484 address selection *
+         */
+    }
+    else
+    {
+        /* IP address parse succeeded */
+        if (flags & GETADDR_RANDOMIZE)
+        {
+            msg(M_WARN, "WARNING: ignoring --remote-random-hostname because the hostname is an IP address");
+        }
+    }
+
+done:
+    if (signal_received && *signal_received)
+    {
+        int level = 0;
+        if (flags & GETADDR_FATAL_ON_SIGNAL)
+        {
+            level = M_FATAL;
+        }
+        else if (flags & GETADDR_WARN_ON_SIGNAL)
+        {
+            level = M_WARN;
+        }
+        msg(level, "RESOLVE: signal received during DNS resolution attempt");
+    }
+
+    gc_free(&gc);
+    return status;
+}
+
+/*
+ * We do our own inet_aton because the glibc function
+ * isn't very good about error checking.
+ */
+int
+openvpn_inet_aton(const char *dotted_quad, struct in_addr *addr)
+{
+    unsigned int a, b, c, d;
+
+    CLEAR(*addr);
+    if (sscanf(dotted_quad, "%u.%u.%u.%u", &a, &b, &c, &d) == 4)
+    {
+        if (a < 256 && b < 256 && c < 256 && d < 256)
+        {
+            addr->s_addr = htonl(a<<24 | b<<16 | c<<8 | d);
+            return OIA_IP; /* good dotted quad */
+        }
+    }
+    if (string_class(dotted_quad, CC_DIGIT|CC_DOT, 0))
+    {
+        return OIA_ERROR; /* probably a badly formatted dotted quad */
+    }
+    else
+    {
+        return OIA_HOSTNAME; /* probably a hostname */
+    }
+}
+
+bool
+ip_addr_dotted_quad_safe(const char *dotted_quad)
+{
+    /* verify non-NULL */
+    if (!dotted_quad)
+    {
+        return false;
+    }
+
+    /* verify length is within limits */
+    if (strlen(dotted_quad) > 15)
+    {
+        return false;
+    }
+
+    /* verify that all chars are either numeric or '.' and that no numeric
+     * substring is greater than 3 chars */
+    {
+        int nnum = 0;
+        const char *p = dotted_quad;
+        int c;
+
+        while ((c = *p++))
+        {
+            if (c >= '0' && c <= '9')
+            {
+                ++nnum;
+                if (nnum > 3)
+                {
+                    return false;
+                }
+            }
+            else if (c == '.')
+            {
+                nnum = 0;
+            }
+            else
+            {
+                return false;
+            }
+        }
+    }
+
+    /* verify that string will convert to IP address */
+    {
+        struct in_addr a;
+        return openvpn_inet_aton(dotted_quad, &a) == OIA_IP;
+    }
+}
+
+bool
+ipv6_addr_safe(const char *ipv6_text_addr)
+{
+    /* verify non-NULL */
+    if (!ipv6_text_addr)
+    {
+        return false;
+    }
+
+    /* verify length is within limits */
+    if (strlen(ipv6_text_addr) > INET6_ADDRSTRLEN)
+    {
+        return false;
+    }
+
+    /* verify that string will convert to IPv6 address */
+    {
+        struct in6_addr a6;
+        return inet_pton( AF_INET6, ipv6_text_addr, &a6 ) == 1;
+    }
+}
+
+static bool
+dns_addr_safe(const char *addr)
+{
+    if (addr)
+    {
+        const size_t len = strlen(addr);
+        return len > 0 && len <= 255 && string_class(addr, CC_ALNUM|CC_DASH|CC_DOT, 0);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+ip_or_dns_addr_safe(const char *addr, const bool allow_fqdn)
+{
+    if (ip_addr_dotted_quad_safe(addr))
+    {
+        return true;
+    }
+    else if (allow_fqdn)
+    {
+        return dns_addr_safe(addr);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+mac_addr_safe(const char *mac_addr)
+{
+    /* verify non-NULL */
+    if (!mac_addr)
+    {
+        return false;
+    }
+
+    /* verify length is within limits */
+    if (strlen(mac_addr) > 17)
+    {
+        return false;
+    }
+
+    /* verify that all chars are either alphanumeric or ':' and that no
+     * alphanumeric substring is greater than 2 chars */
+    {
+        int nnum = 0;
+        const char *p = mac_addr;
+        int c;
+
+        while ((c = *p++))
+        {
+            if ( (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') )
+            {
+                ++nnum;
+                if (nnum > 2)
+                {
+                    return false;
+                }
+            }
+            else if (c == ':')
+            {
+                nnum = 0;
+            }
+            else
+            {
+                return false;
+            }
+        }
+    }
+
+    /* error-checking is left to script invoked in lladdr.c */
+    return true;
+}
+
+static int
+socket_get_sndbuf(int sd)
+{
+#if defined(HAVE_GETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_SNDBUF)
+    int val;
+    socklen_t len;
+
+    len = sizeof(val);
+    if (getsockopt(sd, SOL_SOCKET, SO_SNDBUF, (void *) &val, &len) == 0
+        && len == sizeof(val))
+    {
+        return val;
+    }
+#endif
+    return 0;
+}
+
+static void
+socket_set_sndbuf(int sd, int size)
+{
+#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_SNDBUF)
+    if (setsockopt(sd, SOL_SOCKET, SO_SNDBUF, (void *) &size, sizeof(size)) != 0)
+    {
+        msg(M_WARN, "NOTE: setsockopt SO_SNDBUF=%d failed", size);
+    }
+#endif
+}
+
+static int
+socket_get_rcvbuf(int sd)
+{
+#if defined(HAVE_GETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_RCVBUF)
+    int val;
+    socklen_t len;
+
+    len = sizeof(val);
+    if (getsockopt(sd, SOL_SOCKET, SO_RCVBUF, (void *) &val, &len) == 0
+        && len == sizeof(val))
+    {
+        return val;
+    }
+#endif
+    return 0;
+}
+
+static bool
+socket_set_rcvbuf(int sd, int size)
+{
+#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_RCVBUF)
+    if (setsockopt(sd, SOL_SOCKET, SO_RCVBUF, (void *) &size, sizeof(size)) != 0)
+    {
+        msg(M_WARN, "NOTE: setsockopt SO_RCVBUF=%d failed", size);
+        return false;
+    }
+    return true;
+#endif
+}
+
+static void
+socket_set_buffers(int fd, const struct socket_buffer_size *sbs)
+{
+    if (sbs)
+    {
+        const int sndbuf_old = socket_get_sndbuf(fd);
+        const int rcvbuf_old = socket_get_rcvbuf(fd);
+
+        if (sbs->sndbuf)
+        {
+            socket_set_sndbuf(fd, sbs->sndbuf);
+        }
+
+        if (sbs->rcvbuf)
+        {
+            socket_set_rcvbuf(fd, sbs->rcvbuf);
+        }
+
+        msg(D_OSBUF, "Socket Buffers: R=[%d->%d] S=[%d->%d]",
+            rcvbuf_old,
+            socket_get_rcvbuf(fd),
+            sndbuf_old,
+            socket_get_sndbuf(fd));
+    }
+}
+
+/*
+ * Set other socket options
+ */
+
+static bool
+socket_set_tcp_nodelay(int sd, int state)
+{
+#if defined(_WIN32) || (defined(HAVE_SETSOCKOPT) && defined(IPPROTO_TCP) && defined(TCP_NODELAY))
+    if (setsockopt(sd, IPPROTO_TCP, TCP_NODELAY, (void *) &state, sizeof(state)) != 0)
+    {
+        msg(M_WARN, "NOTE: setsockopt TCP_NODELAY=%d failed", state);
+        return false;
+    }
+    else
+    {
+        dmsg(D_OSBUF, "Socket flags: TCP_NODELAY=%d succeeded", state);
+        return true;
+    }
+#else  /* if defined(_WIN32) || (defined(HAVE_SETSOCKOPT) && defined(IPPROTO_TCP) && defined(TCP_NODELAY)) */
+    msg(M_WARN, "NOTE: setsockopt TCP_NODELAY=%d failed (No kernel support)", state);
+    return false;
+#endif
+}
+
+static inline void
+socket_set_mark(int sd, int mark)
+{
+#if defined(TARGET_LINUX) && HAVE_DECL_SO_MARK
+    if (mark && setsockopt(sd, SOL_SOCKET, SO_MARK, (void *) &mark, sizeof(mark)) != 0)
+    {
+        msg(M_WARN, "NOTE: setsockopt SO_MARK=%d failed", mark);
+    }
+#endif
+}
+
+static bool
+socket_set_flags(int sd, unsigned int sockflags)
+{
+    if (sockflags & SF_TCP_NODELAY)
+    {
+        return socket_set_tcp_nodelay(sd, 1);
+    }
+    else
+    {
+        return true;
+    }
+}
+
+bool
+link_socket_update_flags(struct link_socket *ls, unsigned int sockflags)
+{
+    if (ls && socket_defined(ls->sd))
+    {
+        return socket_set_flags(ls->sd, ls->sockflags = sockflags);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+void
+link_socket_update_buffer_sizes(struct link_socket *ls, int rcvbuf, int sndbuf)
+{
+    if (ls && socket_defined(ls->sd))
+    {
+        ls->socket_buffer_sizes.sndbuf = sndbuf;
+        ls->socket_buffer_sizes.rcvbuf = rcvbuf;
+        socket_set_buffers(ls->sd, &ls->socket_buffer_sizes);
+    }
+}
+
+/*
+ * SOCKET INITALIZATION CODE.
+ * Create a TCP/UDP socket
+ */
+
+socket_descriptor_t
+create_socket_tcp(struct addrinfo *addrinfo)
+{
+    socket_descriptor_t sd;
+
+    ASSERT(addrinfo);
+    ASSERT(addrinfo->ai_socktype == SOCK_STREAM);
+
+    if ((sd = socket(addrinfo->ai_family, addrinfo->ai_socktype, addrinfo->ai_protocol)) < 0)
+    {
+        msg(M_ERR, "Cannot create TCP socket");
+    }
+
+#ifndef _WIN32 /* using SO_REUSEADDR on Windows will cause bind to succeed on port conflicts! */
+    /* set SO_REUSEADDR on socket */
+    {
+        int on = 1;
+        if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR,
+                       (void *) &on, sizeof(on)) < 0)
+        {
+            msg(M_ERR, "TCP: Cannot setsockopt SO_REUSEADDR on TCP socket");
+        }
+    }
+#endif
+
+    /* set socket file descriptor to not pass across execs, so that
+     * scripts don't have access to it */
+    set_cloexec(sd);
+
+    return sd;
+}
+
+static socket_descriptor_t
+create_socket_udp(struct addrinfo *addrinfo, const unsigned int flags)
+{
+    socket_descriptor_t sd;
+
+    ASSERT(addrinfo);
+    ASSERT(addrinfo->ai_socktype == SOCK_DGRAM);
+
+    if ((sd = socket(addrinfo->ai_family, addrinfo->ai_socktype, addrinfo->ai_protocol)) < 0)
+    {
+        msg(M_ERR, "UDP: Cannot create UDP/UDP6 socket");
+    }
+#if ENABLE_IP_PKTINFO
+    else if (flags & SF_USE_IP_PKTINFO)
+    {
+        int pad = 1;
+        if (addrinfo->ai_family == AF_INET)
+        {
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+            if (setsockopt(sd, SOL_IP, IP_PKTINFO,
+                           (void *)&pad, sizeof(pad)) < 0)
+            {
+                msg(M_ERR, "UDP: failed setsockopt for IP_PKTINFO");
+            }
+#elif defined(IP_RECVDSTADDR)
+            if (setsockopt(sd, IPPROTO_IP, IP_RECVDSTADDR,
+                           (void *)&pad, sizeof(pad)) < 0)
+            {
+                msg(M_ERR, "UDP: failed setsockopt for IP_RECVDSTADDR");
+            }
+#else  /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+#error ENABLE_IP_PKTINFO is set without IP_PKTINFO xor IP_RECVDSTADDR (fix syshead.h)
+#endif
+        }
+        else if (addrinfo->ai_family == AF_INET6)
+        {
+#ifndef IPV6_RECVPKTINFO /* Some older Darwin platforms require this */
+            if (setsockopt(sd, IPPROTO_IPV6, IPV6_PKTINFO,
+                           (void *)&pad, sizeof(pad)) < 0)
+#else
+            if (setsockopt(sd, IPPROTO_IPV6, IPV6_RECVPKTINFO,
+                           (void *)&pad, sizeof(pad)) < 0)
+#endif
+            { msg(M_ERR, "UDP: failed setsockopt for IPV6_RECVPKTINFO");}
+        }
+    }
+#endif /* if ENABLE_IP_PKTINFO */
+
+    /* set socket file descriptor to not pass across execs, so that
+     * scripts don't have access to it */
+    set_cloexec(sd);
+
+    return sd;
+}
+
+static void
+bind_local(struct link_socket *sock, const sa_family_t ai_family)
+{
+    /* bind to local address/port */
+    if (sock->bind_local)
+    {
+        if (sock->socks_proxy && sock->info.proto == PROTO_UDP)
+        {
+            socket_bind(sock->ctrl_sd, sock->info.lsa->bind_local,
+                        ai_family, "SOCKS", false);
+        }
+        else
+        {
+            socket_bind(sock->sd, sock->info.lsa->bind_local,
+                        ai_family,
+                        "TCP/UDP", sock->info.bind_ipv6_only);
+        }
+    }
+}
+
+static void
+create_socket(struct link_socket *sock, struct addrinfo *addr)
+{
+    if (addr->ai_protocol == IPPROTO_UDP || addr->ai_socktype == SOCK_DGRAM)
+    {
+        sock->sd = create_socket_udp(addr, sock->sockflags);
+        sock->sockflags |= SF_GETADDRINFO_DGRAM;
+
+        /* Assume that control socket and data socket to the socks proxy
+         * are using the same IP family */
+        if (sock->socks_proxy)
+        {
+            /* Construct a temporary addrinfo to create the socket,
+             * currently resolve two remote addresses is not supported,
+             * TODO: Rewrite the whole resolve_remote */
+            struct addrinfo addrinfo_tmp = *addr;
+            addrinfo_tmp.ai_socktype = SOCK_STREAM;
+            addrinfo_tmp.ai_protocol = IPPROTO_TCP;
+            sock->ctrl_sd = create_socket_tcp(&addrinfo_tmp);
+        }
+    }
+    else if (addr->ai_protocol == IPPROTO_TCP || addr->ai_socktype == SOCK_STREAM)
+    {
+        sock->sd = create_socket_tcp(addr);
+    }
+    else
+    {
+        ASSERT(0);
+    }
+    /* set socket buffers based on --sndbuf and --rcvbuf options */
+    socket_set_buffers(sock->sd, &sock->socket_buffer_sizes);
+
+    /* set socket to --mark packets with given value */
+    socket_set_mark(sock->sd, sock->mark);
+
+    bind_local(sock, addr->ai_family);
+}
+
+#ifdef TARGET_ANDROID
+static void
+protect_fd_nonlocal(int fd, const struct sockaddr *addr)
+{
+    /* pass socket FD to management interface to pass on to VPNService API
+     * as "protected socket" (exempt from being routed into tunnel)
+     */
+    if (addr_local(addr))
+    {
+        msg(D_SOCKET_DEBUG, "Address is local, not protecting socket fd %d", fd);
+        return;
+    }
+
+    msg(D_SOCKET_DEBUG, "Protecting socket fd %d", fd);
+    management->connection.fdtosend = fd;
+    management_android_control(management, "PROTECTFD", __func__);
+}
+#endif
+
+/*
+ * Functions used for establishing a TCP stream connection.
+ */
+static void
+socket_do_listen(socket_descriptor_t sd,
+                 const struct addrinfo *local,
+                 bool do_listen,
+                 bool do_set_nonblock)
+{
+    struct gc_arena gc = gc_new();
+    if (do_listen)
+    {
+        ASSERT(local);
+        msg(M_INFO, "Listening for incoming TCP connection on %s",
+            print_sockaddr(local->ai_addr, &gc));
+        if (listen(sd, 32))
+        {
+            msg(M_ERR, "TCP: listen() failed");
+        }
+    }
+
+    /* set socket to non-blocking mode */
+    if (do_set_nonblock)
+    {
+        set_nonblock(sd);
+    }
+
+    gc_free(&gc);
+}
+
+socket_descriptor_t
+socket_do_accept(socket_descriptor_t sd,
+                 struct link_socket_actual *act,
+                 const bool nowait)
+{
+    /* af_addr_size WILL return 0 in this case if AFs other than AF_INET
+     * are compiled because act is empty here.
+     * could use getsockname() to support later remote_len check
+     */
+    socklen_t remote_len_af = af_addr_size(act->dest.addr.sa.sa_family);
+    socklen_t remote_len = sizeof(act->dest.addr);
+    socket_descriptor_t new_sd = SOCKET_UNDEFINED;
+
+    CLEAR(*act);
+
+#ifdef HAVE_GETPEERNAME
+    if (nowait)
+    {
+        new_sd = getpeername(sd, &act->dest.addr.sa, &remote_len);
+
+        if (!socket_defined(new_sd))
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "TCP: getpeername() failed");
+        }
+        else
+        {
+            new_sd = sd;
+        }
+    }
+#else  /* ifdef HAVE_GETPEERNAME */
+    if (nowait)
+    {
+        msg(M_WARN, "TCP: this OS does not provide the getpeername() function");
+    }
+#endif
+    else
+    {
+        new_sd = accept(sd, &act->dest.addr.sa, &remote_len);
+    }
+
+#if 0 /* For debugging only, test the effect of accept() failures */
+    {
+        static int foo = 0;
+        ++foo;
+        if (foo & 1)
+        {
+            new_sd = -1;
+        }
+    }
+#endif
+
+    if (!socket_defined(new_sd))
+    {
+        msg(D_LINK_ERRORS | M_ERRNO, "TCP: accept(%d) failed", (int)sd);
+    }
+    /* only valid if we have remote_len_af!=0 */
+    else if (remote_len_af && remote_len != remote_len_af)
+    {
+        msg(D_LINK_ERRORS, "TCP: Received strange incoming connection with unknown address length=%d", remote_len);
+        openvpn_close_socket(new_sd);
+        new_sd = SOCKET_UNDEFINED;
+    }
+    else
+    {
+        /* set socket file descriptor to not pass across execs, so that
+         * scripts don't have access to it */
+        set_cloexec(sd);
+    }
+    return new_sd;
+}
+
+static void
+tcp_connection_established(const struct link_socket_actual *act)
+{
+    struct gc_arena gc = gc_new();
+    msg(M_INFO, "TCP connection established with %s",
+        print_link_socket_actual(act, &gc));
+    gc_free(&gc);
+}
+
+static socket_descriptor_t
+socket_listen_accept(socket_descriptor_t sd,
+                     struct link_socket_actual *act,
+                     const char *remote_dynamic,
+                     const struct addrinfo *local,
+                     bool do_listen,
+                     bool nowait,
+                     volatile int *signal_received)
+{
+    struct gc_arena gc = gc_new();
+    /* struct openvpn_sockaddr *remote = &act->dest; */
+    struct openvpn_sockaddr remote_verify = act->dest;
+    socket_descriptor_t new_sd = SOCKET_UNDEFINED;
+
+    CLEAR(*act);
+    socket_do_listen(sd, local, do_listen, true);
+
+    while (true)
+    {
+        int status;
+        fd_set reads;
+        struct timeval tv;
+
+        FD_ZERO(&reads);
+        openvpn_fd_set(sd, &reads);
+        tv.tv_sec = 0;
+        tv.tv_usec = 0;
+
+        status = select(sd + 1, &reads, NULL, NULL, &tv);
+
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            gc_free(&gc);
+            return sd;
+        }
+
+        if (status < 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "TCP: select() failed");
+        }
+
+        if (status <= 0)
+        {
+            management_sleep(1);
+            continue;
+        }
+
+        new_sd = socket_do_accept(sd, act, nowait);
+
+        if (socket_defined(new_sd))
+        {
+            struct addrinfo *ai = NULL;
+            if (remote_dynamic)
+            {
+                openvpn_getaddrinfo(0, remote_dynamic, NULL, 1, NULL,
+                                    remote_verify.addr.sa.sa_family, &ai);
+            }
+
+            if (ai && !addrlist_match(&remote_verify, ai))
+            {
+                msg(M_WARN,
+                    "TCP NOTE: Rejected connection attempt from %s due to --remote setting",
+                    print_link_socket_actual(act, &gc));
+                if (openvpn_close_socket(new_sd))
+                {
+                    msg(M_ERR, "TCP: close socket failed (new_sd)");
+                }
+                freeaddrinfo(ai);
+            }
+            else
+            {
+                if (ai)
+                {
+                    freeaddrinfo(ai);
+                }
+                break;
+            }
+        }
+        management_sleep(1);
+    }
+
+    if (!nowait && openvpn_close_socket(sd))
+    {
+        msg(M_ERR, "TCP: close socket failed (sd)");
+    }
+
+    tcp_connection_established(act);
+
+    gc_free(&gc);
+    return new_sd;
+}
+
+/* older mingw versions and WinXP do not have this define,
+ * but Vista and up support the functionality - just define it here
+ */
+#ifdef _WIN32
+#ifndef IPV6_V6ONLY
+#define IPV6_V6ONLY 27
+#endif
+#endif
+void
+socket_bind(socket_descriptor_t sd,
+            struct addrinfo *local,
+            int ai_family,
+            const char *prefix,
+            bool ipv6only)
+{
+    struct gc_arena gc = gc_new();
+
+    /* FIXME (schwabe)
+     * getaddrinfo for the bind address might return multiple AF_INET/AF_INET6
+     * entries for the requested protocol.
+     * For example if an address has multiple A records
+     * What is the correct way to deal with it?
+     */
+
+    struct addrinfo *cur;
+
+    ASSERT(local);
+
+
+    /* find the first addrinfo with correct ai_family */
+    for (cur = local; cur; cur = cur->ai_next)
+    {
+        if (cur->ai_family == ai_family)
+        {
+            break;
+        }
+    }
+    if (!cur)
+    {
+        msg(M_FATAL, "%s: Socket bind failed: Addr to bind has no %s record",
+            prefix, addr_family_name(ai_family));
+    }
+
+    if (ai_family == AF_INET6)
+    {
+        int v6only = ipv6only ? 1 : 0;  /* setsockopt must have an "int" */
+
+        msg(M_INFO, "setsockopt(IPV6_V6ONLY=%d)", v6only);
+        if (setsockopt(sd, IPPROTO_IPV6, IPV6_V6ONLY, (void *) &v6only, sizeof(v6only)))
+        {
+            msg(M_NONFATAL|M_ERRNO, "Setting IPV6_V6ONLY=%d failed", v6only);
+        }
+    }
+    if (bind(sd, cur->ai_addr, cur->ai_addrlen))
+    {
+        msg(M_FATAL | M_ERRNO, "%s: Socket bind failed on local address %s",
+            prefix,
+            print_sockaddr_ex(local->ai_addr, ":", PS_SHOW_PORT, &gc));
+    }
+    gc_free(&gc);
+}
+
+int
+openvpn_connect(socket_descriptor_t sd,
+                const struct sockaddr *remote,
+                int connect_timeout,
+                volatile int *signal_received)
+{
+    int status = 0;
+
+#ifdef TARGET_ANDROID
+    protect_fd_nonlocal(sd, remote);
+#endif
+
+#ifdef CONNECT_NONBLOCK
+    set_nonblock(sd);
+    status = connect(sd, remote, af_addr_size(remote->sa_family));
+    if (status)
+    {
+        status = openvpn_errno();
+    }
+    if (
+#ifdef _WIN32
+        status == WSAEWOULDBLOCK
+#else
+        status == EINPROGRESS
+#endif
+        )
+    {
+        while (true)
+        {
+#if POLL
+            struct pollfd fds[1];
+            fds[0].fd = sd;
+            fds[0].events = POLLOUT;
+            status = poll(fds, 1, 0);
+#else
+            fd_set writes;
+            struct timeval tv;
+
+            FD_ZERO(&writes);
+            openvpn_fd_set(sd, &writes);
+            tv.tv_sec = 0;
+            tv.tv_usec = 0;
+
+            status = select(sd + 1, NULL, &writes, NULL, &tv);
+#endif
+            if (signal_received)
+            {
+                get_signal(signal_received);
+                if (*signal_received)
+                {
+                    status = 0;
+                    break;
+                }
+            }
+            if (status < 0)
+            {
+                status = openvpn_errno();
+                break;
+            }
+            if (status <= 0)
+            {
+                if (--connect_timeout < 0)
+                {
+#ifdef _WIN32
+                    status = WSAETIMEDOUT;
+#else
+                    status = ETIMEDOUT;
+#endif
+                    break;
+                }
+                management_sleep(1);
+                continue;
+            }
+
+            /* got it */
+            {
+                int val = 0;
+                socklen_t len;
+
+                len = sizeof(val);
+                if (getsockopt(sd, SOL_SOCKET, SO_ERROR, (void *) &val, &len) == 0
+                    && len == sizeof(val))
+                {
+                    status = val;
+                }
+                else
+                {
+                    status = openvpn_errno();
+                }
+                break;
+            }
+        }
+    }
+#else  /* ifdef CONNECT_NONBLOCK */
+    status = connect(sd, remote, af_addr_size(remote->sa_family));
+    if (status)
+    {
+        status = openvpn_errno();
+    }
+#endif /* ifdef CONNECT_NONBLOCK */
+
+    return status;
+}
+
+void
+set_actual_address(struct link_socket_actual *actual, struct addrinfo *ai)
+{
+    CLEAR(*actual);
+    ASSERT(ai);
+
+    if (ai->ai_family == AF_INET)
+    {
+        actual->dest.addr.in4 =
+            *((struct sockaddr_in *) ai->ai_addr);
+    }
+    else if (ai->ai_family == AF_INET6)
+    {
+        actual->dest.addr.in6 =
+            *((struct sockaddr_in6 *) ai->ai_addr);
+    }
+    else
+    {
+        ASSERT(0);
+    }
+
+}
+
+static void
+socket_connect(socket_descriptor_t *sd,
+               const struct sockaddr *dest,
+               const int connect_timeout,
+               struct signal_info *sig_info)
+{
+    struct gc_arena gc = gc_new();
+    int status;
+
+#ifdef CONNECT_NONBLOCK
+    msg(M_INFO, "Attempting to establish TCP connection with %s [nonblock]",
+        print_sockaddr(dest, &gc));
+#else
+    msg(M_INFO, "Attempting to establish TCP connection with %s",
+        print_sockaddr(dest, &gc));
+#endif
+
+#ifdef ENABLE_MANAGEMENT
+    if (management)
+    {
+        management_set_state(management,
+                             OPENVPN_STATE_TCP_CONNECT,
+                             NULL,
+                             NULL,
+                             NULL,
+                             NULL,
+                             NULL);
+    }
+#endif
+
+    /* Set the actual address */
+    status = openvpn_connect(*sd, dest, connect_timeout, &sig_info->signal_received);
+
+    get_signal(&sig_info->signal_received);
+    if (sig_info->signal_received)
+    {
+        goto done;
+    }
+
+    if (status)
+    {
+
+        msg(D_LINK_ERRORS, "TCP: connect to %s failed: %s",
+            print_sockaddr(dest, &gc), strerror(status));
+
+        openvpn_close_socket(*sd);
+        *sd = SOCKET_UNDEFINED;
+        sig_info->signal_received = SIGUSR1;
+        sig_info->source = SIG_SOURCE_CONNECTION_FAILED;
+    }
+    else
+    {
+        msg(M_INFO, "TCP connection established with %s",
+            print_sockaddr(dest, &gc));
+    }
+
+done:
+    gc_free(&gc);
+}
+
+/* For stream protocols, allocate a buffer to build up packet.
+ * Called after frame has been finalized. */
+
+static void
+socket_frame_init(const struct frame *frame, struct link_socket *sock)
+{
+#ifdef _WIN32
+    overlapped_io_init(&sock->reads, frame, FALSE, false);
+    overlapped_io_init(&sock->writes, frame, TRUE, false);
+    sock->rw_handle.read = sock->reads.overlapped.hEvent;
+    sock->rw_handle.write = sock->writes.overlapped.hEvent;
+#endif
+
+    if (link_socket_connection_oriented(sock))
+    {
+#ifdef _WIN32
+        stream_buf_init(&sock->stream_buf,
+                        &sock->reads.buf_init,
+                        sock->sockflags,
+                        sock->info.proto);
+#else
+        alloc_buf_sock_tun(&sock->stream_buf_data,
+                           frame,
+                           false,
+                           FRAME_HEADROOM_MARKER_READ_STREAM);
+
+        stream_buf_init(&sock->stream_buf,
+                        &sock->stream_buf_data,
+                        sock->sockflags,
+                        sock->info.proto);
+#endif
+    }
+}
+
+/*
+ * Adjust frame structure based on a Path MTU value given
+ * to us by the OS.
+ */
+void
+frame_adjust_path_mtu(struct frame *frame, int pmtu, int proto)
+{
+    frame_set_mtu_dynamic(frame, pmtu - datagram_overhead(proto), SET_MTU_UPPER_BOUND);
+}
+
+static void
+resolve_bind_local(struct link_socket *sock, const sa_family_t af)
+{
+    struct gc_arena gc = gc_new();
+
+    /* resolve local address if undefined */
+    if (!sock->info.lsa->bind_local)
+    {
+        int flags = GETADDR_RESOLVE | GETADDR_WARN_ON_SIGNAL
+                    |GETADDR_FATAL | GETADDR_PASSIVE;
+        int status;
+
+        if (proto_is_dgram(sock->info.proto))
+        {
+            flags |= GETADDR_DATAGRAM;
+        }
+
+        /* will return AF_{INET|INET6}from local_host */
+        status = get_cached_dns_entry(sock->dns_cache,
+                                      sock->local_host,
+                                      sock->local_port,
+                                      af,
+                                      flags,
+                                      &sock->info.lsa->bind_local);
+
+        if (status)
+        {
+            status = openvpn_getaddrinfo(flags, sock->local_host, sock->local_port, 0,
+                                         NULL, af, &sock->info.lsa->bind_local);
+        }
+
+        if (status !=0)
+        {
+            msg(M_FATAL, "getaddrinfo() failed for local \"%s:%s\": %s",
+                sock->local_host, sock->local_port,
+                gai_strerror(status));
+        }
+    }
+
+    gc_free(&gc);
+}
+
+static void
+resolve_remote(struct link_socket *sock,
+               int phase,
+               const char **remote_dynamic,
+               volatile int *signal_received)
+{
+    struct gc_arena gc = gc_new();
+
+    /* resolve remote address if undefined */
+    if (!sock->info.lsa->remote_list)
+    {
+        if (sock->remote_host)
+        {
+            unsigned int flags = sf2gaf(GETADDR_RESOLVE|GETADDR_UPDATE_MANAGEMENT_STATE, sock->sockflags);
+            int retry = 0;
+            int status = -1;
+            struct addrinfo *ai;
+            if (proto_is_dgram(sock->info.proto))
+            {
+                flags |= GETADDR_DATAGRAM;
+            }
+
+            if (sock->resolve_retry_seconds == RESOLV_RETRY_INFINITE)
+            {
+                if (phase == 2)
+                {
+                    flags |= (GETADDR_TRY_ONCE | GETADDR_FATAL);
+                }
+                retry = 0;
+            }
+            else if (phase == 1)
+            {
+                if (sock->resolve_retry_seconds)
+                {
+                    retry = 0;
+                }
+                else
+                {
+                    flags |= (GETADDR_FATAL | GETADDR_MENTION_RESOLVE_RETRY);
+                    retry = 0;
+                }
+            }
+            else if (phase == 2)
+            {
+                if (sock->resolve_retry_seconds)
+                {
+                    flags |= GETADDR_FATAL;
+                    retry = sock->resolve_retry_seconds;
+                }
+                else
+                {
+                    ASSERT(0);
+                }
+            }
+            else
+            {
+                ASSERT(0);
+            }
+
+
+            status = get_cached_dns_entry(sock->dns_cache,
+                                          sock->remote_host,
+                                          sock->remote_port,
+                                          sock->info.af,
+                                          flags, &ai);
+            if (status)
+            {
+                status = openvpn_getaddrinfo(flags, sock->remote_host, sock->remote_port,
+                                             retry, signal_received, sock->info.af, &ai);
+            }
+
+            if (status == 0)
+            {
+                sock->info.lsa->remote_list = ai;
+                sock->info.lsa->current_remote = ai;
+
+                dmsg(D_SOCKET_DEBUG, "RESOLVE_REMOTE flags=0x%04x phase=%d rrs=%d sig=%d status=%d",
+                     flags,
+                     phase,
+                     retry,
+                     signal_received ? *signal_received : -1,
+                     status);
+            }
+            if (signal_received)
+            {
+                if (*signal_received)
+                {
+                    goto done;
+                }
+            }
+            if (status!=0)
+            {
+                if (signal_received)
+                {
+                    *signal_received = SIGUSR1;
+                }
+                goto done;
+            }
+        }
+    }
+
+    /* should we re-use previous active remote address? */
+    if (link_socket_actual_defined(&sock->info.lsa->actual))
+    {
+        msg(M_INFO, "TCP/UDP: Preserving recently used remote address: %s",
+            print_link_socket_actual(&sock->info.lsa->actual, &gc));
+        if (remote_dynamic)
+        {
+            *remote_dynamic = NULL;
+        }
+    }
+    else
+    {
+        CLEAR(sock->info.lsa->actual);
+        if (sock->info.lsa->current_remote)
+        {
+            set_actual_address(&sock->info.lsa->actual,
+                               sock->info.lsa->current_remote);
+        }
+    }
+
+done:
+    gc_free(&gc);
+}
+
+
+
+struct link_socket *
+link_socket_new(void)
+{
+    struct link_socket *sock;
+
+    ALLOC_OBJ_CLEAR(sock, struct link_socket);
+    sock->sd = SOCKET_UNDEFINED;
+    sock->ctrl_sd = SOCKET_UNDEFINED;
+    return sock;
+}
+
+void
+link_socket_init_phase1(struct link_socket *sock,
+                        const char *local_host,
+                        const char *local_port,
+                        const char *remote_host,
+                        const char *remote_port,
+                        struct cached_dns_entry *dns_cache,
+                        int proto,
+                        sa_family_t af,
+                        bool bind_ipv6_only,
+                        int mode,
+                        const struct link_socket *accept_from,
+                        struct http_proxy_info *http_proxy,
+                        struct socks_proxy_info *socks_proxy,
+#ifdef ENABLE_DEBUG
+                        int gremlin,
+#endif
+                        bool bind_local,
+                        bool remote_float,
+                        int inetd,
+                        struct link_socket_addr *lsa,
+                        const char *ipchange_command,
+                        const struct plugin_list *plugins,
+                        int resolve_retry_seconds,
+                        int mtu_discover_type,
+                        int rcvbuf,
+                        int sndbuf,
+                        int mark,
+                        struct event_timeout *server_poll_timeout,
+                        unsigned int sockflags)
+{
+    ASSERT(sock);
+
+    sock->local_host = local_host;
+    sock->local_port = local_port;
+    sock->remote_host = remote_host;
+    sock->remote_port = remote_port;
+    sock->dns_cache = dns_cache;
+    sock->http_proxy = http_proxy;
+    sock->socks_proxy = socks_proxy;
+    sock->bind_local = bind_local;
+    sock->inetd = inetd;
+    sock->resolve_retry_seconds = resolve_retry_seconds;
+    sock->mtu_discover_type = mtu_discover_type;
+
+#ifdef ENABLE_DEBUG
+    sock->gremlin = gremlin;
+#endif
+
+    sock->socket_buffer_sizes.rcvbuf = rcvbuf;
+    sock->socket_buffer_sizes.sndbuf = sndbuf;
+
+    sock->sockflags = sockflags;
+    sock->mark = mark;
+
+    sock->info.proto = proto;
+    sock->info.af = af;
+    sock->info.remote_float = remote_float;
+    sock->info.lsa = lsa;
+    sock->info.bind_ipv6_only = bind_ipv6_only;
+    sock->info.ipchange_command = ipchange_command;
+    sock->info.plugins = plugins;
+    sock->server_poll_timeout = server_poll_timeout;
+
+    sock->mode = mode;
+    if (mode == LS_MODE_TCP_ACCEPT_FROM)
+    {
+        ASSERT(accept_from);
+        ASSERT(sock->info.proto == PROTO_TCP_SERVER);
+        ASSERT(!sock->inetd);
+        sock->sd = accept_from->sd;
+        /* inherit (possibly guessed) info AF from parent context */
+        sock->info.af = accept_from->info.af;
+    }
+
+    /* are we running in HTTP proxy mode? */
+    if (sock->http_proxy)
+    {
+        ASSERT(sock->info.proto == PROTO_TCP_CLIENT);
+        ASSERT(!sock->inetd);
+
+        /* the proxy server */
+        sock->remote_host = http_proxy->options.server;
+        sock->remote_port = http_proxy->options.port;
+
+        /* the OpenVPN server we will use the proxy to connect to */
+        sock->proxy_dest_host = remote_host;
+        sock->proxy_dest_port = remote_port;
+    }
+    /* or in Socks proxy mode? */
+    else if (sock->socks_proxy)
+    {
+        ASSERT(!sock->inetd);
+
+        /* the proxy server */
+        sock->remote_host = socks_proxy->server;
+        sock->remote_port = socks_proxy->port;
+
+        /* the OpenVPN server we will use the proxy to connect to */
+        sock->proxy_dest_host = remote_host;
+        sock->proxy_dest_port = remote_port;
+    }
+    else
+    {
+        sock->remote_host = remote_host;
+        sock->remote_port = remote_port;
+    }
+
+    /* bind behavior for TCP server vs. client */
+    if (sock->info.proto == PROTO_TCP_SERVER)
+    {
+        if (sock->mode == LS_MODE_TCP_ACCEPT_FROM)
+        {
+            sock->bind_local = false;
+        }
+        else
+        {
+            sock->bind_local = true;
+        }
+    }
+
+    /* were we started by inetd or xinetd? */
+    if (sock->inetd)
+    {
+        ASSERT(sock->info.proto != PROTO_TCP_CLIENT);
+        ASSERT(socket_defined(inetd_socket_descriptor));
+        sock->sd = inetd_socket_descriptor;
+        set_cloexec(sock->sd);          /* not created by create_socket*() */
+    }
+    else if (mode != LS_MODE_TCP_ACCEPT_FROM)
+    {
+        if (sock->bind_local)
+        {
+            resolve_bind_local(sock, sock->info.af);
+        }
+        resolve_remote(sock, 1, NULL, NULL);
+    }
+}
+
+static
+void
+phase2_inetd(struct link_socket *sock, const struct frame *frame,
+             const char *remote_dynamic, volatile int *signal_received)
+{
+    bool remote_changed = false;
+
+    if (sock->info.proto == PROTO_TCP_SERVER)
+    {
+        /* AF_INET as default (and fallback) for inetd */
+        sock->info.lsa->actual.dest.addr.sa.sa_family = AF_INET;
+#ifdef HAVE_GETSOCKNAME
+        {
+            /* inetd: hint family type for dest = local's */
+            struct openvpn_sockaddr local_addr;
+            socklen_t addrlen = sizeof(local_addr);
+            if (getsockname(sock->sd, &local_addr.addr.sa, &addrlen) == 0)
+            {
+                sock->info.lsa->actual.dest.addr.sa.sa_family = local_addr.addr.sa.sa_family;
+                dmsg(D_SOCKET_DEBUG, "inetd(%s): using sa_family=%d from getsockname(%d)",
+                     proto2ascii(sock->info.proto, sock->info.af, false),
+                     local_addr.addr.sa.sa_family, (int)sock->sd);
+            }
+            else
+            {
+                msg(M_WARN, "inetd(%s): getsockname(%d) failed, using AF_INET",
+                    proto2ascii(sock->info.proto, sock->info.af, false), (int)sock->sd);
+            }
+        }
+#else  /* ifdef HAVE_GETSOCKNAME */
+        msg(M_WARN, "inetd(%s): this OS does not provide the getsockname() "
+            "function, using AF_INET",
+            proto2ascii(sock->info.proto, false));
+#endif /* ifdef HAVE_GETSOCKNAME */
+        sock->sd =
+            socket_listen_accept(sock->sd,
+                                 &sock->info.lsa->actual,
+                                 remote_dynamic,
+                                 sock->info.lsa->bind_local,
+                                 false,
+                                 sock->inetd == INETD_NOWAIT,
+                                 signal_received);
+
+    }
+    ASSERT(!remote_changed);
+}
+
+static void
+phase2_set_socket_flags(struct link_socket *sock)
+{
+    /* set misc socket parameters */
+    socket_set_flags(sock->sd, sock->sockflags);
+
+    /* set socket to non-blocking mode */
+    set_nonblock(sock->sd);
+
+    /* set Path MTU discovery options on the socket */
+    set_mtu_discover_type(sock->sd, sock->mtu_discover_type, sock->info.af);
+
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+    /* if the OS supports it, enable extended error passing on the socket */
+    set_sock_extended_error_passing(sock->sd);
+#endif
+}
+
+
+static void
+linksock_print_addr(struct link_socket *sock)
+{
+    struct gc_arena gc = gc_new();
+    const int msglevel = (sock->mode == LS_MODE_TCP_ACCEPT_FROM) ? D_INIT_MEDIUM : M_INFO;
+
+    /* print local address */
+    if (sock->inetd)
+    {
+        msg(msglevel, "%s link local: [inetd]", proto2ascii(sock->info.proto, sock->info.af, true));
+    }
+    else if (sock->bind_local)
+    {
+        sa_family_t ai_family = sock->info.lsa->actual.dest.addr.sa.sa_family;
+        /* Socket is always bound on the first matching address,
+         * For bound sockets with no remote addr this is the element of
+         * the list */
+        struct addrinfo *cur;
+        for (cur = sock->info.lsa->bind_local; cur; cur = cur->ai_next)
+        {
+            if (!ai_family || ai_family == cur->ai_family)
+            {
+                break;
+            }
+        }
+        ASSERT(cur);
+        msg(msglevel, "%s link local (bound): %s",
+            proto2ascii(sock->info.proto, sock->info.af, true),
+            print_sockaddr(cur->ai_addr,&gc));
+    }
+    else
+    {
+        msg(msglevel, "%s link local: (not bound)",
+            proto2ascii(sock->info.proto, sock->info.af, true));
+    }
+
+    /* print active remote address */
+    msg(msglevel, "%s link remote: %s",
+        proto2ascii(sock->info.proto, sock->info.af, true),
+        print_link_socket_actual_ex(&sock->info.lsa->actual,
+                                    ":",
+                                    PS_SHOW_PORT_IF_DEFINED,
+                                    &gc));
+    gc_free(&gc);
+}
+
+static void
+phase2_tcp_server(struct link_socket *sock, const char *remote_dynamic,
+                  volatile int *signal_received)
+{
+    switch (sock->mode)
+    {
+        case LS_MODE_DEFAULT:
+            sock->sd = socket_listen_accept(sock->sd,
+                                            &sock->info.lsa->actual,
+                                            remote_dynamic,
+                                            sock->info.lsa->bind_local,
+                                            true,
+                                            false,
+                                            signal_received);
+            break;
+
+        case LS_MODE_TCP_LISTEN:
+            socket_do_listen(sock->sd,
+                             sock->info.lsa->bind_local,
+                             true,
+                             false);
+            break;
+
+        case LS_MODE_TCP_ACCEPT_FROM:
+            sock->sd = socket_do_accept(sock->sd,
+                                        &sock->info.lsa->actual,
+                                        false);
+            if (!socket_defined(sock->sd))
+            {
+                *signal_received = SIGTERM;
+                return;
+            }
+            tcp_connection_established(&sock->info.lsa->actual);
+            break;
+
+        default:
+            ASSERT(0);
+    }
+}
+
+
+static void
+phase2_tcp_client(struct link_socket *sock, struct signal_info *sig_info)
+{
+    bool proxy_retry = false;
+    do
+    {
+        socket_connect(&sock->sd,
+                       sock->info.lsa->current_remote->ai_addr,
+                       get_server_poll_remaining_time(sock->server_poll_timeout),
+                       sig_info);
+
+        if (sig_info->signal_received)
+        {
+            return;
+        }
+
+        if (sock->http_proxy)
+        {
+            proxy_retry = establish_http_proxy_passthru(sock->http_proxy,
+                                                        sock->sd,
+                                                        sock->proxy_dest_host,
+                                                        sock->proxy_dest_port,
+                                                        sock->server_poll_timeout,
+                                                        &sock->stream_buf.residual,
+                                                        &sig_info->signal_received);
+        }
+        else if (sock->socks_proxy)
+        {
+            establish_socks_proxy_passthru(sock->socks_proxy,
+                                           sock->sd,
+                                           sock->proxy_dest_host,
+                                           sock->proxy_dest_port,
+                                           &sig_info->signal_received);
+        }
+        if (proxy_retry)
+        {
+            openvpn_close_socket(sock->sd);
+            sock->sd = create_socket_tcp(sock->info.lsa->current_remote);
+        }
+
+    } while (proxy_retry);
+
+}
+
+static void
+phase2_socks_client(struct link_socket *sock, struct signal_info *sig_info)
+{
+    socket_connect(&sock->ctrl_sd,
+                   sock->info.lsa->current_remote->ai_addr,
+                   get_server_poll_remaining_time(sock->server_poll_timeout),
+                   sig_info);
+
+    if (sig_info->signal_received)
+    {
+        return;
+    }
+
+    establish_socks_proxy_udpassoc(sock->socks_proxy,
+                                   sock->ctrl_sd,
+                                   sock->sd,
+                                   &sock->socks_relay.dest,
+                                   &sig_info->signal_received);
+
+    if (sig_info->signal_received)
+    {
+        return;
+    }
+
+    sock->remote_host = sock->proxy_dest_host;
+    sock->remote_port = sock->proxy_dest_port;
+
+    addr_zero_host(&sock->info.lsa->actual.dest);
+    if (sock->info.lsa->remote_list)
+    {
+        freeaddrinfo(sock->info.lsa->remote_list);
+        sock->info.lsa->current_remote = NULL;
+        sock->info.lsa->remote_list = NULL;
+    }
+
+    resolve_remote(sock, 1, NULL, &sig_info->signal_received);
+}
+
+/* finalize socket initialization */
+void
+link_socket_init_phase2(struct link_socket *sock,
+                        const struct frame *frame,
+                        struct signal_info *sig_info)
+{
+    const char *remote_dynamic = NULL;
+    int sig_save = 0;
+
+    ASSERT(sock);
+    ASSERT(sig_info);
+
+    if (sig_info->signal_received)
+    {
+        sig_save = sig_info->signal_received;
+        sig_info->signal_received = 0;
+    }
+
+    /* initialize buffers */
+    socket_frame_init(frame, sock);
+
+    /*
+     * Pass a remote name to connect/accept so that
+     * they can test for dynamic IP address changes
+     * and throw a SIGUSR1 if appropriate.
+     */
+    if (sock->resolve_retry_seconds)
+    {
+        remote_dynamic = sock->remote_host;
+    }
+
+    /* were we started by inetd or xinetd? */
+    if (sock->inetd)
+    {
+        phase2_inetd(sock, frame, remote_dynamic,  &sig_info->signal_received);
+        if (sig_info->signal_received)
+        {
+            goto done;
+        }
+
+    }
+    else
+    {
+        /* Second chance to resolv/create socket */
+        resolve_remote(sock, 2, &remote_dynamic,  &sig_info->signal_received);
+
+        /* If a valid remote has been found, create the socket with its addrinfo */
+        if (sock->info.lsa->current_remote)
+        {
+            create_socket(sock, sock->info.lsa->current_remote);
+        }
+
+        /* If socket has not already been created create it now */
+        if (sock->sd == SOCKET_UNDEFINED)
+        {
+            /* If we have no --remote and have still not figured out the
+             * protocol family to use we will use the first of the bind */
+
+            if (sock->bind_local  && !sock->remote_host && sock->info.lsa->bind_local)
+            {
+                /* Warn if this is because neither v4 or v6 was specified
+                 * and we should not connect a remote */
+                if (sock->info.af == AF_UNSPEC)
+                {
+                    msg(M_WARN, "Could not determine IPv4/IPv6 protocol. Using %s",
+                        addr_family_name(sock->info.lsa->bind_local->ai_family));
+                    sock->info.af = sock->info.lsa->bind_local->ai_family;
+                }
+
+                create_socket(sock, sock->info.lsa->bind_local);
+            }
+        }
+
+        /* Socket still undefined, give a warning and abort connection */
+        if (sock->sd == SOCKET_UNDEFINED)
+        {
+            msg(M_WARN, "Could not determine IPv4/IPv6 protocol");
+            sig_info->signal_received = SIGUSR1;
+            goto done;
+        }
+
+        if (sig_info->signal_received)
+        {
+            goto done;
+        }
+
+        if (sock->info.proto == PROTO_TCP_SERVER)
+        {
+            phase2_tcp_server(sock, remote_dynamic,
+                              &sig_info->signal_received);
+        }
+        else if (sock->info.proto == PROTO_TCP_CLIENT)
+        {
+            phase2_tcp_client(sock, sig_info);
+
+        }
+        else if (sock->info.proto == PROTO_UDP && sock->socks_proxy)
+        {
+            phase2_socks_client(sock, sig_info);
+        }
+#ifdef TARGET_ANDROID
+        if (sock->sd != -1)
+        {
+            protect_fd_nonlocal(sock->sd, &sock->info.lsa->actual.dest.addr.sa);
+        }
+#endif
+        if (sig_info->signal_received)
+        {
+            goto done;
+        }
+    }
+
+    phase2_set_socket_flags(sock);
+    linksock_print_addr(sock);
+
+done:
+    if (sig_save)
+    {
+        if (!sig_info->signal_received)
+        {
+            sig_info->signal_received = sig_save;
+        }
+    }
+}
+
+void
+link_socket_close(struct link_socket *sock)
+{
+    if (sock)
+    {
+#ifdef ENABLE_DEBUG
+        const int gremlin = GREMLIN_CONNECTION_FLOOD_LEVEL(sock->gremlin);
+#else
+        const int gremlin = 0;
+#endif
+
+        if (socket_defined(sock->sd))
+        {
+#ifdef _WIN32
+            close_net_event_win32(&sock->listen_handle, sock->sd, 0);
+#endif
+            if (!gremlin)
+            {
+                msg(D_LOW, "TCP/UDP: Closing socket");
+                if (openvpn_close_socket(sock->sd))
+                {
+                    msg(M_WARN | M_ERRNO, "TCP/UDP: Close Socket failed");
+                }
+            }
+            sock->sd = SOCKET_UNDEFINED;
+#ifdef _WIN32
+            if (!gremlin)
+            {
+                overlapped_io_close(&sock->reads);
+                overlapped_io_close(&sock->writes);
+            }
+#endif
+        }
+
+        if (socket_defined(sock->ctrl_sd))
+        {
+            if (openvpn_close_socket(sock->ctrl_sd))
+            {
+                msg(M_WARN | M_ERRNO, "TCP/UDP: Close Socket (ctrl_sd) failed");
+            }
+            sock->ctrl_sd = SOCKET_UNDEFINED;
+        }
+
+        stream_buf_close(&sock->stream_buf);
+        free_buf(&sock->stream_buf_data);
+        if (!gremlin)
+        {
+            free(sock);
+        }
+    }
+}
+
+/* for stream protocols, allow for packet length prefix */
+void
+socket_adjust_frame_parameters(struct frame *frame, int proto)
+{
+    if (link_socket_proto_connection_oriented(proto))
+    {
+        frame_add_to_extra_frame(frame, sizeof(packet_size_type));
+    }
+}
+
+void
+setenv_trusted(struct env_set *es, const struct link_socket_info *info)
+{
+    setenv_link_socket_actual(es, "trusted", &info->lsa->actual, SA_IP_PORT);
+}
+
+static void
+ipchange_fmt(const bool include_cmd, struct argv *argv, const struct link_socket_info *info, struct gc_arena *gc)
+{
+    const char *host = print_sockaddr_ex(&info->lsa->actual.dest.addr.sa, " ", PS_SHOW_PORT, gc);
+    if (include_cmd)
+    {
+        argv_parse_cmd(argv, info->ipchange_command);
+        argv_printf_cat(argv, "%s", host);
+    }
+    else
+    {
+        argv_printf(argv, "%s", host);
+    }
+
+}
+
+void
+link_socket_connection_initiated(const struct buffer *buf,
+                                 struct link_socket_info *info,
+                                 const struct link_socket_actual *act,
+                                 const char *common_name,
+                                 struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+
+    info->lsa->actual = *act; /* Note: skip this line for --force-dest */
+    setenv_trusted(es, info);
+    info->connection_established = true;
+
+    /* Print connection initiated message, with common name if available */
+    {
+        struct buffer out = alloc_buf_gc(256, &gc);
+        if (common_name)
+        {
+            buf_printf(&out, "[%s] ", common_name);
+        }
+        buf_printf(&out, "Peer Connection Initiated with %s", print_link_socket_actual(&info->lsa->actual, &gc));
+        msg(M_INFO, "%s", BSTR(&out));
+    }
+
+    /* set environmental vars */
+    setenv_str(es, "common_name", common_name);
+
+    /* Process --ipchange plugin */
+    if (plugin_defined(info->plugins, OPENVPN_PLUGIN_IPCHANGE))
+    {
+        struct argv argv = argv_new();
+        ipchange_fmt(false, &argv, info, &gc);
+        if (plugin_call(info->plugins, OPENVPN_PLUGIN_IPCHANGE, &argv, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            msg(M_WARN, "WARNING: ipchange plugin call failed");
+        }
+        argv_reset(&argv);
+    }
+
+    /* Process --ipchange option */
+    if (info->ipchange_command)
+    {
+        struct argv argv = argv_new();
+        setenv_str(es, "script_type", "ipchange");
+        ipchange_fmt(true, &argv, info, &gc);
+        openvpn_run_script(&argv, es, 0, "--ipchange");
+        argv_reset(&argv);
+    }
+
+    gc_free(&gc);
+}
+
+void
+link_socket_bad_incoming_addr(struct buffer *buf,
+                              const struct link_socket_info *info,
+                              const struct link_socket_actual *from_addr)
+{
+    struct gc_arena gc = gc_new();
+    struct addrinfo *ai;
+
+    switch (from_addr->dest.addr.sa.sa_family)
+    {
+        case AF_INET:
+        case AF_INET6:
+            msg(D_LINK_ERRORS,
+                "TCP/UDP: Incoming packet rejected from %s[%d], expected peer address: %s (allow this incoming source address/port by removing --remote or adding --float)",
+                print_link_socket_actual(from_addr, &gc),
+                (int)from_addr->dest.addr.sa.sa_family,
+                print_sockaddr_ex(info->lsa->remote_list->ai_addr,":",PS_SHOW_PORT, &gc));
+            /* print additional remote addresses */
+            for (ai = info->lsa->remote_list->ai_next; ai; ai = ai->ai_next)
+            {
+                msg(D_LINK_ERRORS,"or from peer address: %s",
+                    print_sockaddr_ex(ai->ai_addr,":",PS_SHOW_PORT, &gc));
+            }
+            break;
+    }
+    buf->len = 0;
+    gc_free(&gc);
+}
+
+void
+link_socket_bad_outgoing_addr(void)
+{
+    dmsg(D_READ_WRITE, "TCP/UDP: No outgoing address to send packet");
+}
+
+in_addr_t
+link_socket_current_remote(const struct link_socket_info *info)
+{
+    const struct link_socket_addr *lsa = info->lsa;
+
+/*
+ * This logic supports "redirect-gateway" semantic, which
+ * makes sense only for PF_INET routes over PF_INET endpoints
+ *
+ * Maybe in the future consider PF_INET6 endpoints also ...
+ * by now just ignore it
+ *
+ * For --remote entries with multiple addresses this
+ * only return the actual endpoint we have sucessfully connected to
+ */
+    if (lsa->actual.dest.addr.sa.sa_family != AF_INET)
+    {
+        return IPV4_INVALID_ADDR;
+    }
+
+    if (link_socket_actual_defined(&lsa->actual))
+    {
+        return ntohl(lsa->actual.dest.addr.in4.sin_addr.s_addr);
+    }
+    else if (lsa->current_remote)
+    {
+        return ntohl(((struct sockaddr_in *)lsa->current_remote->ai_addr)
+                     ->sin_addr.s_addr);
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+const struct in6_addr *
+link_socket_current_remote_ipv6(const struct link_socket_info *info)
+{
+    const struct link_socket_addr *lsa = info->lsa;
+
+/* This logic supports "redirect-gateway" semantic,
+ * for PF_INET6 routes over PF_INET6 endpoints
+ *
+ * For --remote entries with multiple addresses this
+ * only return the actual endpoint we have sucessfully connected to
+ */
+    if (lsa->actual.dest.addr.sa.sa_family != AF_INET6)
+    {
+        return NULL;
+    }
+
+    if (link_socket_actual_defined(&lsa->actual))
+    {
+        return &(lsa->actual.dest.addr.in6.sin6_addr);
+    }
+    else if (lsa->current_remote)
+    {
+        return &(((struct sockaddr_in6 *)lsa->current_remote->ai_addr)->sin6_addr);
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+/*
+ * Return a status string describing socket state.
+ */
+const char *
+socket_stat(const struct link_socket *s, unsigned int rwflags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    if (s)
+    {
+        if (rwflags & EVENT_READ)
+        {
+            buf_printf(&out, "S%s",
+                       (s->rwflags_debug & EVENT_READ) ? "R" : "r");
+#ifdef _WIN32
+            buf_printf(&out, "%s",
+                       overlapped_io_state_ascii(&s->reads));
+#endif
+        }
+        if (rwflags & EVENT_WRITE)
+        {
+            buf_printf(&out, "S%s",
+                       (s->rwflags_debug & EVENT_WRITE) ? "W" : "w");
+#ifdef _WIN32
+            buf_printf(&out, "%s",
+                       overlapped_io_state_ascii(&s->writes));
+#endif
+        }
+    }
+    else
+    {
+        buf_printf(&out, "S?");
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Stream buffer functions, used to packetize a TCP
+ * stream connection.
+ */
+
+static inline void
+stream_buf_reset(struct stream_buf *sb)
+{
+    dmsg(D_STREAM_DEBUG, "STREAM: RESET");
+    sb->residual_fully_formed = false;
+    sb->buf = sb->buf_init;
+    buf_reset(&sb->next);
+    sb->len = -1;
+}
+
+void
+stream_buf_init(struct stream_buf *sb,
+                struct buffer *buf,
+                const unsigned int sockflags,
+                const int proto)
+{
+    sb->buf_init = *buf;
+    sb->maxlen = sb->buf_init.len;
+    sb->buf_init.len = 0;
+    sb->residual = alloc_buf(sb->maxlen);
+    sb->error = false;
+#if PORT_SHARE
+    sb->port_share_state = ((sockflags & SF_PORT_SHARE) && (proto == PROTO_TCP_SERVER))
+                           ? PS_ENABLED
+                           : PS_DISABLED;
+#endif
+    stream_buf_reset(sb);
+
+    dmsg(D_STREAM_DEBUG, "STREAM: INIT maxlen=%d", sb->maxlen);
+}
+
+static inline void
+stream_buf_set_next(struct stream_buf *sb)
+{
+    /* set up 'next' for next i/o read */
+    sb->next = sb->buf;
+    sb->next.offset = sb->buf.offset + sb->buf.len;
+    sb->next.len = (sb->len >= 0 ? sb->len : sb->maxlen) - sb->buf.len;
+    dmsg(D_STREAM_DEBUG, "STREAM: SET NEXT, buf=[%d,%d] next=[%d,%d] len=%d maxlen=%d",
+         sb->buf.offset, sb->buf.len,
+         sb->next.offset, sb->next.len,
+         sb->len, sb->maxlen);
+    ASSERT(sb->next.len > 0);
+    ASSERT(buf_safe(&sb->buf, sb->next.len));
+}
+
+static inline void
+stream_buf_get_final(struct stream_buf *sb, struct buffer *buf)
+{
+    dmsg(D_STREAM_DEBUG, "STREAM: GET FINAL len=%d",
+         buf_defined(&sb->buf) ? sb->buf.len : -1);
+    ASSERT(buf_defined(&sb->buf));
+    *buf = sb->buf;
+}
+
+static inline void
+stream_buf_get_next(struct stream_buf *sb, struct buffer *buf)
+{
+    dmsg(D_STREAM_DEBUG, "STREAM: GET NEXT len=%d",
+         buf_defined(&sb->next) ? sb->next.len : -1);
+    ASSERT(buf_defined(&sb->next));
+    *buf = sb->next;
+}
+
+bool
+stream_buf_read_setup_dowork(struct link_socket *sock)
+{
+    if (sock->stream_buf.residual.len && !sock->stream_buf.residual_fully_formed)
+    {
+        ASSERT(buf_copy(&sock->stream_buf.buf, &sock->stream_buf.residual));
+        ASSERT(buf_init(&sock->stream_buf.residual, 0));
+        sock->stream_buf.residual_fully_formed = stream_buf_added(&sock->stream_buf, 0);
+        dmsg(D_STREAM_DEBUG, "STREAM: RESIDUAL FULLY FORMED [%s], len=%d",
+             sock->stream_buf.residual_fully_formed ? "YES" : "NO",
+             sock->stream_buf.residual.len);
+    }
+
+    if (!sock->stream_buf.residual_fully_formed)
+    {
+        stream_buf_set_next(&sock->stream_buf);
+    }
+    return !sock->stream_buf.residual_fully_formed;
+}
+
+bool
+stream_buf_added(struct stream_buf *sb,
+                 int length_added)
+{
+    dmsg(D_STREAM_DEBUG, "STREAM: ADD length_added=%d", length_added);
+    if (length_added > 0)
+    {
+        sb->buf.len += length_added;
+    }
+
+    /* if length unknown, see if we can get the length prefix from
+     * the head of the buffer */
+    if (sb->len < 0 && sb->buf.len >= (int) sizeof(packet_size_type))
+    {
+        packet_size_type net_size;
+
+#if PORT_SHARE
+        if (sb->port_share_state == PS_ENABLED)
+        {
+            if (!is_openvpn_protocol(&sb->buf))
+            {
+                msg(D_STREAM_ERRORS, "Non-OpenVPN client protocol detected");
+                sb->port_share_state = PS_FOREIGN;
+                sb->error = true;
+                return false;
+            }
+            else
+            {
+                sb->port_share_state = PS_DISABLED;
+            }
+        }
+#endif
+
+        ASSERT(buf_read(&sb->buf, &net_size, sizeof(net_size)));
+        sb->len = ntohps(net_size);
+
+        if (sb->len < 1 || sb->len > sb->maxlen)
+        {
+            msg(M_WARN, "WARNING: Bad encapsulated packet length from peer (%d), which must be > 0 and <= %d -- please ensure that --tun-mtu or --link-mtu is equal on both peers -- this condition could also indicate a possible active attack on the TCP link -- [Attempting restart...]", sb->len, sb->maxlen);
+            stream_buf_reset(sb);
+            sb->error = true;
+            return false;
+        }
+    }
+
+    /* is our incoming packet fully read? */
+    if (sb->len > 0 && sb->buf.len >= sb->len)
+    {
+        /* save any residual data that's part of the next packet */
+        ASSERT(buf_init(&sb->residual, 0));
+        if (sb->buf.len > sb->len)
+        {
+            ASSERT(buf_copy_excess(&sb->residual, &sb->buf, sb->len));
+        }
+        dmsg(D_STREAM_DEBUG, "STREAM: ADD returned TRUE, buf_len=%d, residual_len=%d",
+             BLEN(&sb->buf),
+             BLEN(&sb->residual));
+        return true;
+    }
+    else
+    {
+        dmsg(D_STREAM_DEBUG, "STREAM: ADD returned FALSE (have=%d need=%d)", sb->buf.len, sb->len);
+        stream_buf_set_next(sb);
+        return false;
+    }
+}
+
+void
+stream_buf_close(struct stream_buf *sb)
+{
+    free_buf(&sb->residual);
+}
+
+/*
+ * The listen event is a special event whose sole purpose is
+ * to tell us that there's a new incoming connection on a
+ * TCP socket, for use in server mode.
+ */
+event_t
+socket_listen_event_handle(struct link_socket *s)
+{
+#ifdef _WIN32
+    if (!defined_net_event_win32(&s->listen_handle))
+    {
+        init_net_event_win32(&s->listen_handle, FD_ACCEPT, s->sd, 0);
+    }
+    return &s->listen_handle;
+#else  /* ifdef _WIN32 */
+    return s->sd;
+#endif
+}
+
+/*
+ * Format IP addresses in ascii
+ */
+
+const char *
+print_sockaddr_ex(const struct sockaddr *sa,
+                  const char *separator,
+                  const unsigned int flags,
+                  struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(128, gc);
+    bool addr_is_defined = false;
+    char hostaddr[NI_MAXHOST] = "";
+    char servname[NI_MAXSERV] = "";
+    int status;
+
+    socklen_t salen = 0;
+    switch (sa->sa_family)
+    {
+        case AF_INET:
+            if (!(flags & PS_DONT_SHOW_FAMILY))
+            {
+                buf_puts(&out, "[AF_INET]");
+            }
+            salen = sizeof(struct sockaddr_in);
+            addr_is_defined = ((struct sockaddr_in *) sa)->sin_addr.s_addr != 0;
+            break;
+
+        case AF_INET6:
+            if (!(flags & PS_DONT_SHOW_FAMILY))
+            {
+                buf_puts(&out, "[AF_INET6]");
+            }
+            salen = sizeof(struct sockaddr_in6);
+            addr_is_defined = !IN6_IS_ADDR_UNSPECIFIED(&((struct sockaddr_in6 *) sa)->sin6_addr);
+            break;
+
+        case AF_UNSPEC:
+            if (!(flags & PS_DONT_SHOW_FAMILY))
+            {
+                return "[AF_UNSPEC]";
+            }
+            else
+            {
+                return "";
+            }
+
+        default:
+            ASSERT(0);
+    }
+
+    status = getnameinfo(sa, salen, hostaddr, sizeof(hostaddr),
+                         servname, sizeof(servname), NI_NUMERICHOST | NI_NUMERICSERV);
+
+    if (status!=0)
+    {
+        buf_printf(&out,"[nameinfo() err: %s]",gai_strerror(status));
+        return BSTR(&out);
+    }
+
+    if (!(flags & PS_DONT_SHOW_ADDR))
+    {
+        if (addr_is_defined)
+        {
+            buf_puts(&out, hostaddr);
+        }
+        else
+        {
+            buf_puts(&out, "[undef]");
+        }
+    }
+
+    if ((flags & PS_SHOW_PORT) || (flags & PS_SHOW_PORT_IF_DEFINED))
+    {
+        if (separator)
+        {
+            buf_puts(&out, separator);
+        }
+
+        buf_puts(&out, servname);
+    }
+
+    return BSTR(&out);
+}
+
+const char *
+print_link_socket_actual(const struct link_socket_actual *act, struct gc_arena *gc)
+{
+    return print_link_socket_actual_ex(act, ":", PS_SHOW_PORT|PS_SHOW_PKTINFO, gc);
+}
+
+#ifndef IF_NAMESIZE
+#define IF_NAMESIZE 16
+#endif
+
+const char *
+print_link_socket_actual_ex(const struct link_socket_actual *act,
+                            const char *separator,
+                            const unsigned int flags,
+                            struct gc_arena *gc)
+{
+    if (act)
+    {
+        char ifname[IF_NAMESIZE] = "[undef]";
+        struct buffer out = alloc_buf_gc(128, gc);
+        buf_printf(&out, "%s", print_sockaddr_ex(&act->dest.addr.sa, separator, flags, gc));
+#if ENABLE_IP_PKTINFO
+        if ((flags & PS_SHOW_PKTINFO) && addr_defined_ipi(act))
+        {
+            switch (act->dest.addr.sa.sa_family)
+            {
+                case AF_INET:
+                {
+                    struct openvpn_sockaddr sa;
+                    CLEAR(sa);
+                    sa.addr.in4.sin_family = AF_INET;
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+                    sa.addr.in4.sin_addr = act->pi.in4.ipi_spec_dst;
+                    if_indextoname(act->pi.in4.ipi_ifindex, ifname);
+#elif defined(IP_RECVDSTADDR)
+                    sa.addr.in4.sin_addr = act->pi.in4;
+                    ifname[0] = 0;
+#else  /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+#error ENABLE_IP_PKTINFO is set without IP_PKTINFO xor IP_RECVDSTADDR (fix syshead.h)
+#endif
+                    buf_printf(&out, " (via %s%%%s)",
+                               print_sockaddr_ex(&sa.addr.sa, separator, 0, gc),
+                               ifname);
+                }
+                break;
+
+                case AF_INET6:
+                {
+                    struct sockaddr_in6 sin6;
+                    char buf[INET6_ADDRSTRLEN] = "[undef]";
+                    CLEAR(sin6);
+                    sin6.sin6_family = AF_INET6;
+                    sin6.sin6_addr = act->pi.in6.ipi6_addr;
+                    if_indextoname(act->pi.in6.ipi6_ifindex, ifname);
+                    if (getnameinfo((struct sockaddr *)&sin6, sizeof(struct sockaddr_in6),
+                                    buf, sizeof(buf), NULL, 0, NI_NUMERICHOST) == 0)
+                    {
+                        buf_printf(&out, " (via %s%%%s)", buf, ifname);
+                    }
+                    else
+                    {
+                        buf_printf(&out, " (via [getnameinfo() err]%%%s)", ifname);
+                    }
+                }
+                break;
+            }
+        }
+#endif /* if ENABLE_IP_PKTINFO */
+        return BSTR(&out);
+    }
+    else
+    {
+        return "[NULL]";
+    }
+}
+
+/*
+ * Convert an in_addr_t in host byte order
+ * to an ascii dotted quad.
+ */
+const char *
+print_in_addr_t(in_addr_t addr, unsigned int flags, struct gc_arena *gc)
+{
+    struct in_addr ia;
+    struct buffer out = alloc_buf_gc(64, gc);
+
+    if (addr || !(flags & IA_EMPTY_IF_UNDEF))
+    {
+        CLEAR(ia);
+        ia.s_addr = (flags & IA_NET_ORDER) ? addr : htonl(addr);
+
+        buf_printf(&out, "%s", inet_ntoa(ia));
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Convert an in6_addr in host byte order
+ * to an ascii representation of an IPv6 address
+ */
+const char *
+print_in6_addr(struct in6_addr a6, unsigned int flags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    char tmp_out_buf[64];       /* inet_ntop wants pointer to buffer */
+
+    if (memcmp(&a6, &in6addr_any, sizeof(a6)) != 0
+        || !(flags & IA_EMPTY_IF_UNDEF))
+    {
+        inet_ntop(AF_INET6, &a6, tmp_out_buf, sizeof(tmp_out_buf)-1);
+        buf_printf(&out, "%s", tmp_out_buf );
+    }
+    return BSTR(&out);
+}
+
+#ifndef UINT8_MAX
+#define UINT8_MAX 0xff
+#endif
+
+/* add some offset to an ipv6 address
+ * (add in steps of 8 bits, taking overflow into next round)
+ */
+struct in6_addr
+add_in6_addr( struct in6_addr base, uint32_t add )
+{
+    int i;
+
+    for (i = 15; i>=0 && add > 0; i--)
+    {
+        register int carry;
+        register uint32_t h;
+
+        h = (unsigned char) base.s6_addr[i];
+        base.s6_addr[i] = (h+add) & UINT8_MAX;
+
+        /* using explicit carry for the 8-bit additions will catch
+         * 8-bit and(!) 32-bit overruns nicely
+         */
+        carry = ((h & 0xff)  + (add & 0xff)) >> 8;
+        add = (add>>8) + carry;
+    }
+    return base;
+}
+
+/* set environmental variables for ip/port in *addr */
+void
+setenv_sockaddr(struct env_set *es, const char *name_prefix, const struct openvpn_sockaddr *addr, const unsigned int flags)
+{
+    char name_buf[256];
+
+    char buf[128];
+    switch (addr->addr.sa.sa_family)
+    {
+        case AF_INET:
+            if (flags & SA_IP_PORT)
+            {
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s_ip", name_prefix);
+            }
+            else
+            {
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s", name_prefix);
+            }
+
+            setenv_str(es, name_buf, inet_ntoa(addr->addr.in4.sin_addr));
+
+            if ((flags & SA_IP_PORT) && addr->addr.in4.sin_port)
+            {
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s_port", name_prefix);
+                setenv_int(es, name_buf, ntohs(addr->addr.in4.sin_port));
+            }
+            break;
+
+        case AF_INET6:
+            if (IN6_IS_ADDR_V4MAPPED( &addr->addr.in6.sin6_addr ))
+            {
+                struct in_addr ia;
+                memcpy(&ia.s_addr, &addr->addr.in6.sin6_addr.s6_addr[12],
+                       sizeof(ia.s_addr));
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s_ip", name_prefix);
+                openvpn_snprintf(buf, sizeof(buf), "%s", inet_ntoa(ia) );
+            }
+            else
+            {
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s_ip6", name_prefix);
+                getnameinfo(&addr->addr.sa, sizeof(struct sockaddr_in6),
+                            buf, sizeof(buf), NULL, 0, NI_NUMERICHOST);
+            }
+            setenv_str(es, name_buf, buf);
+
+            if ((flags & SA_IP_PORT) && addr->addr.in6.sin6_port)
+            {
+                openvpn_snprintf(name_buf, sizeof(name_buf), "%s_port", name_prefix);
+                setenv_int(es, name_buf, ntohs(addr->addr.in6.sin6_port));
+            }
+            break;
+    }
+}
+
+void
+setenv_in_addr_t(struct env_set *es, const char *name_prefix, in_addr_t addr, const unsigned int flags)
+{
+    if (addr || !(flags & SA_SET_IF_NONZERO))
+    {
+        struct openvpn_sockaddr si;
+        CLEAR(si);
+        si.addr.in4.sin_family = AF_INET;
+        si.addr.in4.sin_addr.s_addr = htonl(addr);
+        setenv_sockaddr(es, name_prefix, &si, flags);
+    }
+}
+
+void
+setenv_in6_addr(struct env_set *es,
+                const char *name_prefix,
+                const struct in6_addr *addr,
+                const unsigned int flags)
+{
+    if (!IN6_IS_ADDR_UNSPECIFIED(addr) || !(flags & SA_SET_IF_NONZERO))
+    {
+        struct openvpn_sockaddr si;
+        CLEAR(si);
+        si.addr.in6.sin6_family = AF_INET6;
+        si.addr.in6.sin6_addr = *addr;
+        setenv_sockaddr(es, name_prefix, &si, flags);
+    }
+}
+
+void
+setenv_link_socket_actual(struct env_set *es,
+                          const char *name_prefix,
+                          const struct link_socket_actual *act,
+                          const unsigned int flags)
+{
+    setenv_sockaddr(es, name_prefix, &act->dest, flags);
+}
+
+/*
+ * Convert protocol names between index and ascii form.
+ */
+
+struct proto_names {
+    const char *short_form;
+    const char *display_form;
+    sa_family_t proto_af;
+    int proto;
+};
+
+/* Indexed by PROTO_x */
+static const struct proto_names proto_names[] = {
+    {"proto-uninitialized",        "proto-NONE", AF_UNSPEC, PROTO_NONE},
+    /* try IPv4 and IPv6 (client), bind dual-stack (server) */
+    {"udp",        "UDP", AF_UNSPEC, PROTO_UDP},
+    {"tcp-server", "TCP_SERVER", AF_UNSPEC, PROTO_TCP_SERVER},
+    {"tcp-client", "TCP_CLIENT", AF_UNSPEC, PROTO_TCP_CLIENT},
+    {"tcp",        "TCP", AF_UNSPEC, PROTO_TCP},
+    /* force IPv4 */
+    {"udp4",       "UDPv4", AF_INET, PROTO_UDP},
+    {"tcp4-server","TCPv4_SERVER", AF_INET, PROTO_TCP_SERVER},
+    {"tcp4-client","TCPv4_CLIENT", AF_INET, PROTO_TCP_CLIENT},
+    {"tcp4",       "TCPv4", AF_INET, PROTO_TCP},
+    /* force IPv6 */
+    {"udp6","UDPv6", AF_INET6, PROTO_UDP},
+    {"tcp6-server","TCPv6_SERVER", AF_INET6, PROTO_TCP_SERVER},
+    {"tcp6-client","TCPv6_CLIENT", AF_INET6, PROTO_TCP_CLIENT},
+    {"tcp6","TCPv6", AF_INET6, PROTO_TCP},
+};
+
+bool
+proto_is_net(int proto)
+{
+    if (proto < 0 || proto >= PROTO_N)
+    {
+        ASSERT(0);
+    }
+    return proto != PROTO_NONE;
+}
+bool
+proto_is_dgram(int proto)
+{
+    return proto_is_udp(proto);
+}
+
+bool
+proto_is_udp(int proto)
+{
+    if (proto < 0 || proto >= PROTO_N)
+    {
+        ASSERT(0);
+    }
+    return proto == PROTO_UDP;
+}
+
+bool
+proto_is_tcp(int proto)
+{
+    if (proto < 0 || proto >= PROTO_N)
+    {
+        ASSERT(0);
+    }
+    return proto == PROTO_TCP_CLIENT || proto == PROTO_TCP_SERVER;
+}
+
+int
+ascii2proto(const char *proto_name)
+{
+    int i;
+    for (i = 0; i < SIZE(proto_names); ++i)
+    {
+        if (!strcmp(proto_name, proto_names[i].short_form))
+        {
+            return proto_names[i].proto;
+        }
+    }
+    return -1;
+}
+
+sa_family_t
+ascii2af(const char *proto_name)
+{
+    int i;
+    for (i = 0; i < SIZE(proto_names); ++i)
+    {
+        if (!strcmp(proto_name, proto_names[i].short_form))
+        {
+            return proto_names[i].proto_af;
+        }
+    }
+    return 0;
+}
+
+const char *
+proto2ascii(int proto, sa_family_t af, bool display_form)
+{
+    unsigned int i;
+    for (i = 0; i < SIZE(proto_names); ++i)
+    {
+        if (proto_names[i].proto_af == af && proto_names[i].proto == proto)
+        {
+            if (display_form)
+            {
+                return proto_names[i].display_form;
+            }
+            else
+            {
+                return proto_names[i].short_form;
+            }
+        }
+    }
+
+    return "[unknown protocol]";
+}
+
+const char *
+proto2ascii_all(struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    int i;
+
+    for (i = 0; i < SIZE(proto_names); ++i)
+    {
+        if (i)
+        {
+            buf_printf(&out, " ");
+        }
+        buf_printf(&out, "[%s]", proto_names[i].short_form);
+    }
+    return BSTR(&out);
+}
+
+const char *
+addr_family_name(int af)
+{
+    switch (af)
+    {
+        case AF_INET:  return "AF_INET";
+
+        case AF_INET6: return "AF_INET6";
+    }
+    return "AF_UNSPEC";
+}
+
+/*
+ * Given a local proto, return local proto
+ * if !remote, or compatible remote proto
+ * if remote.
+ *
+ * This is used for options compatibility
+ * checking.
+ *
+ * IPv6 and IPv4 protocols are comptabile but OpenVPN
+ * has always sent UDPv4, TCPv4 over the wire. Keep these
+ * strings for backward compatbility
+ */
+const char *
+proto_remote(int proto, bool remote)
+{
+    ASSERT(proto >= 0 && proto < PROTO_N);
+    if (proto == PROTO_UDP)
+    {
+        return "UDPv4";
+    }
+
+    if ( (remote && proto == PROTO_TCP_CLIENT)
+         || (!remote && proto == PROTO_TCP_SERVER))
+    {
+        return "TCPv4_SERVER";
+    }
+    if ( (remote && proto == PROTO_TCP_SERVER)
+         || (!remote && proto == PROTO_TCP_CLIENT))
+    {
+        return "TCPv4_CLIENT";
+    }
+
+    ASSERT(0);
+    return ""; /* Make the compiler happy */
+}
+
+/*
+ * Bad incoming address lengths that differ from what
+ * we expect are considered to be fatal errors.
+ */
+void
+bad_address_length(int actual, int expected)
+{
+    msg(M_FATAL, "ERROR: received strange incoming packet with an address length of %d -- we only accept address lengths of %d.",
+        actual,
+        expected);
+}
+
+/*
+ * Socket Read Routines
+ */
+
+int
+link_socket_read_tcp(struct link_socket *sock,
+                     struct buffer *buf)
+{
+    int len = 0;
+
+    if (!sock->stream_buf.residual_fully_formed)
+    {
+#ifdef _WIN32
+        len = socket_finalize(sock->sd, &sock->reads, buf, NULL);
+#else
+        struct buffer frag;
+        stream_buf_get_next(&sock->stream_buf, &frag);
+        len = recv(sock->sd, BPTR(&frag), BLEN(&frag), MSG_NOSIGNAL);
+#endif
+
+        if (!len)
+        {
+            sock->stream_reset = true;
+        }
+        if (len <= 0)
+        {
+            return buf->len = len;
+        }
+    }
+
+    if (sock->stream_buf.residual_fully_formed
+        || stream_buf_added(&sock->stream_buf, len)) /* packet complete? */
+    {
+        stream_buf_get_final(&sock->stream_buf, buf);
+        stream_buf_reset(&sock->stream_buf);
+        return buf->len;
+    }
+    else
+    {
+        return buf->len = 0; /* no error, but packet is still incomplete */
+    }
+}
+
+#ifndef _WIN32
+
+#if ENABLE_IP_PKTINFO
+
+/* make the buffer large enough to handle ancilliary socket data for
+ * both IPv4 and IPv6 destination addresses, plus padding (see RFC 2292)
+ */
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+#define PKTINFO_BUF_SIZE max_int( CMSG_SPACE(sizeof(struct in6_pktinfo)), \
+                                  CMSG_SPACE(sizeof(struct in_pktinfo)) )
+#else
+#define PKTINFO_BUF_SIZE max_int( CMSG_SPACE(sizeof(struct in6_pktinfo)), \
+                                  CMSG_SPACE(sizeof(struct in_addr)) )
+#endif
+
+static socklen_t
+link_socket_read_udp_posix_recvmsg(struct link_socket *sock,
+                                   struct buffer *buf,
+                                   struct link_socket_actual *from)
+{
+    struct iovec iov;
+    uint8_t pktinfo_buf[PKTINFO_BUF_SIZE];
+    struct msghdr mesg;
+    socklen_t fromlen = sizeof(from->dest.addr);
+
+    iov.iov_base = BPTR(buf);
+    iov.iov_len = buf_forward_capacity_total(buf);
+    mesg.msg_iov = &iov;
+    mesg.msg_iovlen = 1;
+    mesg.msg_name = &from->dest.addr;
+    mesg.msg_namelen = fromlen;
+    mesg.msg_control = pktinfo_buf;
+    mesg.msg_controllen = sizeof pktinfo_buf;
+    buf->len = recvmsg(sock->sd, &mesg, 0);
+    if (buf->len >= 0)
+    {
+        struct cmsghdr *cmsg;
+        fromlen = mesg.msg_namelen;
+        cmsg = CMSG_FIRSTHDR(&mesg);
+        if (cmsg != NULL
+            && CMSG_NXTHDR(&mesg, cmsg) == NULL
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+            && cmsg->cmsg_level == SOL_IP
+            && cmsg->cmsg_type == IP_PKTINFO
+            && cmsg->cmsg_len >= CMSG_LEN(sizeof(struct in_pktinfo)) )
+#elif defined(IP_RECVDSTADDR)
+            && cmsg->cmsg_level == IPPROTO_IP
+            && cmsg->cmsg_type == IP_RECVDSTADDR
+            && cmsg->cmsg_len >= CMSG_LEN(sizeof(struct in_addr)) )
+#else  /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+#error ENABLE_IP_PKTINFO is set without IP_PKTINFO xor IP_RECVDSTADDR (fix syshead.h)
+#endif
+        {
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+            struct in_pktinfo *pkti = (struct in_pktinfo *) CMSG_DATA(cmsg);
+            from->pi.in4.ipi_ifindex = pkti->ipi_ifindex;
+            from->pi.in4.ipi_spec_dst = pkti->ipi_spec_dst;
+#elif defined(IP_RECVDSTADDR)
+            from->pi.in4 = *(struct in_addr *) CMSG_DATA(cmsg);
+#else  /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+#error ENABLE_IP_PKTINFO is set without IP_PKTINFO xor IP_RECVDSTADDR (fix syshead.h)
+#endif
+        }
+        else if (cmsg != NULL
+                 && CMSG_NXTHDR(&mesg, cmsg) == NULL
+                 && cmsg->cmsg_level == IPPROTO_IPV6
+                 && cmsg->cmsg_type == IPV6_PKTINFO
+                 && cmsg->cmsg_len >= CMSG_LEN(sizeof(struct in6_pktinfo)) )
+        {
+            struct in6_pktinfo *pkti6 = (struct in6_pktinfo *) CMSG_DATA(cmsg);
+            from->pi.in6.ipi6_ifindex = pkti6->ipi6_ifindex;
+            from->pi.in6.ipi6_addr = pkti6->ipi6_addr;
+        }
+        else if (cmsg != NULL)
+        {
+            msg(M_WARN, "CMSG received that cannot be parsed (cmsg_level=%d, cmsg_type=%d, cmsg=len=%d)", (int)cmsg->cmsg_level, (int)cmsg->cmsg_type, (int)cmsg->cmsg_len );
+        }
+    }
+
+    return fromlen;
+}
+#endif /* if ENABLE_IP_PKTINFO */
+
+int
+link_socket_read_udp_posix(struct link_socket *sock,
+                           struct buffer *buf,
+                           struct link_socket_actual *from)
+{
+    socklen_t fromlen = sizeof(from->dest.addr);
+    socklen_t expectedlen = af_addr_size(sock->info.af);
+    addr_zero_host(&from->dest);
+#if ENABLE_IP_PKTINFO
+    /* Both PROTO_UDPv4 and PROTO_UDPv6 */
+    if (sock->info.proto == PROTO_UDP && sock->sockflags & SF_USE_IP_PKTINFO)
+    {
+        fromlen = link_socket_read_udp_posix_recvmsg(sock, buf, from);
+    }
+    else
+#endif
+    buf->len = recvfrom(sock->sd, BPTR(buf), buf_forward_capacity(buf), 0,
+                        &from->dest.addr.sa, &fromlen);
+    /* FIXME: won't do anything when sock->info.af == AF_UNSPEC */
+    if (buf->len >= 0 && expectedlen && fromlen != expectedlen)
+    {
+        bad_address_length(fromlen, expectedlen);
+    }
+    return buf->len;
+}
+
+#endif /* ifndef _WIN32 */
+
+/*
+ * Socket Write Routines
+ */
+
+int
+link_socket_write_tcp(struct link_socket *sock,
+                      struct buffer *buf,
+                      struct link_socket_actual *to)
+{
+    packet_size_type len = BLEN(buf);
+    dmsg(D_STREAM_DEBUG, "STREAM: WRITE %d offset=%d", (int)len, buf->offset);
+    ASSERT(len <= sock->stream_buf.maxlen);
+    len = htonps(len);
+    ASSERT(buf_write_prepend(buf, &len, sizeof(len)));
+#ifdef _WIN32
+    return link_socket_write_win32(sock, buf, to);
+#else
+    return link_socket_write_tcp_posix(sock, buf, to);
+#endif
+}
+
+#if ENABLE_IP_PKTINFO
+
+size_t
+link_socket_write_udp_posix_sendmsg(struct link_socket *sock,
+                                    struct buffer *buf,
+                                    struct link_socket_actual *to)
+{
+    struct iovec iov;
+    struct msghdr mesg;
+    struct cmsghdr *cmsg;
+    uint8_t pktinfo_buf[PKTINFO_BUF_SIZE];
+
+    iov.iov_base = BPTR(buf);
+    iov.iov_len = BLEN(buf);
+    mesg.msg_iov = &iov;
+    mesg.msg_iovlen = 1;
+    switch (to->dest.addr.sa.sa_family)
+    {
+        case AF_INET:
+        {
+            mesg.msg_name = &to->dest.addr.sa;
+            mesg.msg_namelen = sizeof(struct sockaddr_in);
+            mesg.msg_control = pktinfo_buf;
+            mesg.msg_flags = 0;
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+            mesg.msg_controllen = CMSG_SPACE(sizeof(struct in_pktinfo));
+            cmsg = CMSG_FIRSTHDR(&mesg);
+            cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
+            cmsg->cmsg_level = SOL_IP;
+            cmsg->cmsg_type = IP_PKTINFO;
+            {
+                struct in_pktinfo *pkti;
+                pkti = (struct in_pktinfo *) CMSG_DATA(cmsg);
+                pkti->ipi_ifindex = to->pi.in4.ipi_ifindex;
+                pkti->ipi_spec_dst = to->pi.in4.ipi_spec_dst;
+                pkti->ipi_addr.s_addr = 0;
+            }
+#elif defined(IP_RECVDSTADDR)
+            ASSERT( CMSG_SPACE(sizeof(struct in_addr)) <= sizeof(pktinfo_buf) );
+            mesg.msg_controllen = CMSG_SPACE(sizeof(struct in_addr));
+            cmsg = CMSG_FIRSTHDR(&mesg);
+            cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
+            cmsg->cmsg_level = IPPROTO_IP;
+            cmsg->cmsg_type = IP_RECVDSTADDR;
+            *(struct in_addr *) CMSG_DATA(cmsg) = to->pi.in4;
+#else  /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+#error ENABLE_IP_PKTINFO is set without IP_PKTINFO xor IP_RECVDSTADDR (fix syshead.h)
+#endif /* if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST) */
+            break;
+        }
+
+        case AF_INET6:
+        {
+            struct in6_pktinfo *pkti6;
+            mesg.msg_name = &to->dest.addr.sa;
+            mesg.msg_namelen = sizeof(struct sockaddr_in6);
+
+            ASSERT( CMSG_SPACE(sizeof(struct in6_pktinfo)) <= sizeof(pktinfo_buf) );
+            mesg.msg_control = pktinfo_buf;
+            mesg.msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
+            mesg.msg_flags = 0;
+            cmsg = CMSG_FIRSTHDR(&mesg);
+            cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
+            cmsg->cmsg_level = IPPROTO_IPV6;
+            cmsg->cmsg_type = IPV6_PKTINFO;
+
+            pkti6 = (struct in6_pktinfo *) CMSG_DATA(cmsg);
+            pkti6->ipi6_ifindex = to->pi.in6.ipi6_ifindex;
+            pkti6->ipi6_addr = to->pi.in6.ipi6_addr;
+            break;
+        }
+
+        default: ASSERT(0);
+    }
+    return sendmsg(sock->sd, &mesg, 0);
+}
+
+#endif /* if ENABLE_IP_PKTINFO */
+
+/*
+ * Win32 overlapped socket I/O functions.
+ */
+
+#ifdef _WIN32
+
+int
+socket_recv_queue(struct link_socket *sock, int maxsize)
+{
+    if (sock->reads.iostate == IOSTATE_INITIAL)
+    {
+        WSABUF wsabuf[1];
+        int status;
+
+        /* reset buf to its initial state */
+        if (proto_is_udp(sock->info.proto))
+        {
+            sock->reads.buf = sock->reads.buf_init;
+        }
+        else if (proto_is_tcp(sock->info.proto))
+        {
+            stream_buf_get_next(&sock->stream_buf, &sock->reads.buf);
+        }
+        else
+        {
+            ASSERT(0);
+        }
+
+        /* Win32 docs say it's okay to allocate the wsabuf on the stack */
+        wsabuf[0].buf = BPTR(&sock->reads.buf);
+        wsabuf[0].len = maxsize ? maxsize : BLEN(&sock->reads.buf);
+
+        /* check for buffer overflow */
+        ASSERT(wsabuf[0].len <= BLEN(&sock->reads.buf));
+
+        /* the overlapped read will signal this event on I/O completion */
+        ASSERT(ResetEvent(sock->reads.overlapped.hEvent));
+        sock->reads.flags = 0;
+
+        if (proto_is_udp(sock->info.proto))
+        {
+            sock->reads.addr_defined = true;
+            sock->reads.addrlen = sizeof(sock->reads.addr6);
+            status = WSARecvFrom(
+                sock->sd,
+                wsabuf,
+                1,
+                &sock->reads.size,
+                &sock->reads.flags,
+                (struct sockaddr *) &sock->reads.addr,
+                &sock->reads.addrlen,
+                &sock->reads.overlapped,
+                NULL);
+        }
+        else if (proto_is_tcp(sock->info.proto))
+        {
+            sock->reads.addr_defined = false;
+            status = WSARecv(
+                sock->sd,
+                wsabuf,
+                1,
+                &sock->reads.size,
+                &sock->reads.flags,
+                &sock->reads.overlapped,
+                NULL);
+        }
+        else
+        {
+            status = 0;
+            ASSERT(0);
+        }
+
+        if (!status) /* operation completed immediately? */
+        {
+            /* FIXME: won't do anything when sock->info.af == AF_UNSPEC */
+            int af_len = af_addr_size(sock->info.af);
+            if (sock->reads.addr_defined && af_len && sock->reads.addrlen != af_len)
+            {
+                bad_address_length(sock->reads.addrlen, af_len);
+            }
+            sock->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+
+            /* since we got an immediate return, we must signal the event object ourselves */
+            ASSERT(SetEvent(sock->reads.overlapped.hEvent));
+            sock->reads.status = 0;
+
+            dmsg(D_WIN32_IO, "WIN32 I/O: Socket Receive immediate return [%d,%d]",
+                 (int) wsabuf[0].len,
+                 (int) sock->reads.size);
+        }
+        else
+        {
+            status = WSAGetLastError();
+            if (status == WSA_IO_PENDING) /* operation queued? */
+            {
+                sock->reads.iostate = IOSTATE_QUEUED;
+                sock->reads.status = status;
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Receive queued [%d]",
+                     (int) wsabuf[0].len);
+            }
+            else /* error occurred */
+            {
+                struct gc_arena gc = gc_new();
+                ASSERT(SetEvent(sock->reads.overlapped.hEvent));
+                sock->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+                sock->reads.status = status;
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Receive error [%d]: %s",
+                     (int) wsabuf[0].len,
+                     strerror_win32(status, &gc));
+                gc_free(&gc);
+            }
+        }
+    }
+    return sock->reads.iostate;
+}
+
+int
+socket_send_queue(struct link_socket *sock, struct buffer *buf, const struct link_socket_actual *to)
+{
+    if (sock->writes.iostate == IOSTATE_INITIAL)
+    {
+        WSABUF wsabuf[1];
+        int status;
+
+        /* make a private copy of buf */
+        sock->writes.buf = sock->writes.buf_init;
+        sock->writes.buf.len = 0;
+        ASSERT(buf_copy(&sock->writes.buf, buf));
+
+        /* Win32 docs say it's okay to allocate the wsabuf on the stack */
+        wsabuf[0].buf = BPTR(&sock->writes.buf);
+        wsabuf[0].len = BLEN(&sock->writes.buf);
+
+        /* the overlapped write will signal this event on I/O completion */
+        ASSERT(ResetEvent(sock->writes.overlapped.hEvent));
+        sock->writes.flags = 0;
+
+        if (proto_is_udp(sock->info.proto))
+        {
+            /* set destination address for UDP writes */
+            sock->writes.addr_defined = true;
+            if (to->dest.addr.sa.sa_family == AF_INET6)
+            {
+                sock->writes.addr6 = to->dest.addr.in6;
+                sock->writes.addrlen = sizeof(sock->writes.addr6);
+            }
+            else
+            {
+                sock->writes.addr = to->dest.addr.in4;
+                sock->writes.addrlen = sizeof(sock->writes.addr);
+            }
+
+            status = WSASendTo(
+                sock->sd,
+                wsabuf,
+                1,
+                &sock->writes.size,
+                sock->writes.flags,
+                (struct sockaddr *) &sock->writes.addr,
+                sock->writes.addrlen,
+                &sock->writes.overlapped,
+                NULL);
+        }
+        else if (proto_is_tcp(sock->info.proto))
+        {
+            /* destination address for TCP writes was established on connection initiation */
+            sock->writes.addr_defined = false;
+
+            status = WSASend(
+                sock->sd,
+                wsabuf,
+                1,
+                &sock->writes.size,
+                sock->writes.flags,
+                &sock->writes.overlapped,
+                NULL);
+        }
+        else
+        {
+            status = 0;
+            ASSERT(0);
+        }
+
+        if (!status) /* operation completed immediately? */
+        {
+            sock->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+
+            /* since we got an immediate return, we must signal the event object ourselves */
+            ASSERT(SetEvent(sock->writes.overlapped.hEvent));
+
+            sock->writes.status = 0;
+
+            dmsg(D_WIN32_IO, "WIN32 I/O: Socket Send immediate return [%d,%d]",
+                 (int) wsabuf[0].len,
+                 (int) sock->writes.size);
+        }
+        else
+        {
+            status = WSAGetLastError();
+            if (status == WSA_IO_PENDING) /* operation queued? */
+            {
+                sock->writes.iostate = IOSTATE_QUEUED;
+                sock->writes.status = status;
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Send queued [%d]",
+                     (int) wsabuf[0].len);
+            }
+            else /* error occurred */
+            {
+                struct gc_arena gc = gc_new();
+                ASSERT(SetEvent(sock->writes.overlapped.hEvent));
+                sock->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+                sock->writes.status = status;
+
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Send error [%d]: %s",
+                     (int) wsabuf[0].len,
+                     strerror_win32(status, &gc));
+
+                gc_free(&gc);
+            }
+        }
+    }
+    return sock->writes.iostate;
+}
+
+int
+socket_finalize(SOCKET s,
+                struct overlapped_io *io,
+                struct buffer *buf,
+                struct link_socket_actual *from)
+{
+    int ret = -1;
+    BOOL status;
+
+    switch (io->iostate)
+    {
+        case IOSTATE_QUEUED:
+            status = WSAGetOverlappedResult(
+                s,
+                &io->overlapped,
+                &io->size,
+                FALSE,
+                &io->flags
+                );
+            if (status)
+            {
+                /* successful return for a queued operation */
+                if (buf)
+                {
+                    *buf = io->buf;
+                }
+                ret = io->size;
+                io->iostate = IOSTATE_INITIAL;
+                ASSERT(ResetEvent(io->overlapped.hEvent));
+
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Completion success [%d]", ret);
+            }
+            else
+            {
+                /* error during a queued operation */
+                ret = -1;
+                if (WSAGetLastError() != WSA_IO_INCOMPLETE)
+                {
+                    /* if no error (i.e. just not finished yet), then DON'T execute this code */
+                    io->iostate = IOSTATE_INITIAL;
+                    ASSERT(ResetEvent(io->overlapped.hEvent));
+                    msg(D_WIN32_IO | M_ERRNO, "WIN32 I/O: Socket Completion error");
+                }
+            }
+            break;
+
+        case IOSTATE_IMMEDIATE_RETURN:
+            io->iostate = IOSTATE_INITIAL;
+            ASSERT(ResetEvent(io->overlapped.hEvent));
+            if (io->status)
+            {
+                /* error return for a non-queued operation */
+                WSASetLastError(io->status);
+                ret = -1;
+                msg(D_WIN32_IO | M_ERRNO, "WIN32 I/O: Socket Completion non-queued error");
+            }
+            else
+            {
+                /* successful return for a non-queued operation */
+                if (buf)
+                {
+                    *buf = io->buf;
+                }
+                ret = io->size;
+                dmsg(D_WIN32_IO, "WIN32 I/O: Socket Completion non-queued success [%d]", ret);
+            }
+            break;
+
+        case IOSTATE_INITIAL: /* were we called without proper queueing? */
+            WSASetLastError(WSAEINVAL);
+            ret = -1;
+            dmsg(D_WIN32_IO, "WIN32 I/O: Socket Completion BAD STATE");
+            break;
+
+        default:
+            ASSERT(0);
+    }
+
+    /* return from address if requested */
+    if (from)
+    {
+        if (ret >= 0 && io->addr_defined)
+        {
+            /* TODO(jjo): streamline this mess */
+            /* in this func we dont have relevant info about the PF_ of this
+             * endpoint, as link_socket_actual will be zero for the 1st received packet
+             *
+             * Test for inets PF_ possible sizes
+             */
+            switch (io->addrlen)
+            {
+                case sizeof(struct sockaddr_in):
+                case sizeof(struct sockaddr_in6):
+                /* TODO(jjo): for some reason (?) I'm getting 24,28 for AF_INET6
+                 * under _WIN32*/
+                case sizeof(struct sockaddr_in6)-4:
+                    break;
+
+                default:
+                    bad_address_length(io->addrlen, af_addr_size(io->addr.sin_family));
+            }
+
+            switch (io->addr.sin_family)
+            {
+                case AF_INET:
+                    from->dest.addr.in4 = io->addr;
+                    break;
+
+                case AF_INET6:
+                    from->dest.addr.in6 = io->addr6;
+                    break;
+            }
+        }
+        else
+        {
+            CLEAR(from->dest.addr);
+        }
+    }
+
+    if (buf)
+    {
+        buf->len = ret;
+    }
+    return ret;
+}
+
+#endif /* _WIN32 */
+
+/*
+ * Socket event notification
+ */
+
+unsigned int
+socket_set(struct link_socket *s,
+           struct event_set *es,
+           unsigned int rwflags,
+           void *arg,
+           unsigned int *persistent)
+{
+    if (s)
+    {
+        if ((rwflags & EVENT_READ) && !stream_buf_read_setup(s))
+        {
+            ASSERT(!persistent);
+            rwflags &= ~EVENT_READ;
+        }
+
+#ifdef _WIN32
+        if (rwflags & EVENT_READ)
+        {
+            socket_recv_queue(s, 0);
+        }
+#endif
+
+        /* if persistent is defined, call event_ctl only if rwflags has changed since last call */
+        if (!persistent || *persistent != rwflags)
+        {
+            event_ctl(es, socket_event_handle(s), rwflags, arg);
+            if (persistent)
+            {
+                *persistent = rwflags;
+            }
+        }
+
+        s->rwflags_debug = rwflags;
+    }
+    return rwflags;
+}
+
+void
+sd_close(socket_descriptor_t *sd)
+{
+    if (sd && socket_defined(*sd))
+    {
+        openvpn_close_socket(*sd);
+        *sd = SOCKET_UNDEFINED;
+    }
+}
+
+#if UNIX_SOCK_SUPPORT
+
+/*
+ * code for unix domain sockets
+ */
+
+const char *
+sockaddr_unix_name(const struct sockaddr_un *local, const char *null)
+{
+    if (local && local->sun_family == PF_UNIX)
+    {
+        return local->sun_path;
+    }
+    else
+    {
+        return null;
+    }
+}
+
+socket_descriptor_t
+create_socket_unix(void)
+{
+    socket_descriptor_t sd;
+
+    if ((sd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0)
+    {
+        msg(M_ERR, "Cannot create unix domain socket");
+    }
+
+    /* set socket file descriptor to not pass across execs, so that
+     * scripts don't have access to it */
+    set_cloexec(sd);
+
+    return sd;
+}
+
+void
+socket_bind_unix(socket_descriptor_t sd,
+                 struct sockaddr_un *local,
+                 const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+
+#ifdef HAVE_UMASK
+    const mode_t orig_umask = umask(0);
+#endif
+
+    if (bind(sd, (struct sockaddr *) local, sizeof(struct sockaddr_un)))
+    {
+        msg(M_FATAL | M_ERRNO,
+            "%s: Socket bind[%d] failed on unix domain socket %s",
+            prefix,
+            (int)sd,
+            sockaddr_unix_name(local, "NULL"));
+    }
+
+#ifdef HAVE_UMASK
+    umask(orig_umask);
+#endif
+
+    gc_free(&gc);
+}
+
+socket_descriptor_t
+socket_accept_unix(socket_descriptor_t sd,
+                   struct sockaddr_un *remote)
+{
+    socklen_t remote_len = sizeof(struct sockaddr_un);
+    socket_descriptor_t ret;
+
+    CLEAR(*remote);
+    ret = accept(sd, (struct sockaddr *) remote, &remote_len);
+    if (ret >= 0)
+    {
+        /* set socket file descriptor to not pass across execs, so that
+         * scripts don't have access to it */
+        set_cloexec(ret);
+    }
+    return ret;
+}
+
+int
+socket_connect_unix(socket_descriptor_t sd,
+                    struct sockaddr_un *remote)
+{
+    int status = connect(sd, (struct sockaddr *) remote, sizeof(struct sockaddr_un));
+    if (status)
+    {
+        status = openvpn_errno();
+    }
+    return status;
+}
+
+void
+sockaddr_unix_init(struct sockaddr_un *local, const char *path)
+{
+    local->sun_family = PF_UNIX;
+    strncpynt(local->sun_path, path, sizeof(local->sun_path));
+}
+
+void
+socket_delete_unix(const struct sockaddr_un *local)
+{
+    const char *name = sockaddr_unix_name(local, NULL);
+#ifdef HAVE_UNLINK
+    if (name && strlen(name))
+    {
+        unlink(name);
+    }
+#endif
+}
+
+bool
+unix_socket_get_peer_uid_gid(const socket_descriptor_t sd, int *uid, int *gid)
+{
+#ifdef HAVE_GETPEEREID
+    uid_t u;
+    gid_t g;
+    if (getpeereid(sd, &u, &g) == -1)
+    {
+        return false;
+    }
+    if (uid)
+    {
+        *uid = u;
+    }
+    if (gid)
+    {
+        *gid = g;
+    }
+    return true;
+#elif defined(SO_PEERCRED)
+    struct ucred peercred;
+    socklen_t so_len = sizeof(peercred);
+    if (getsockopt(sd, SOL_SOCKET, SO_PEERCRED, &peercred, &so_len) == -1)
+    {
+        return false;
+    }
+    if (uid)
+    {
+        *uid = peercred.uid;
+    }
+    if (gid)
+    {
+        *gid = peercred.gid;
+    }
+    return true;
+#else  /* ifdef HAVE_GETPEEREID */
+    return false;
+#endif /* ifdef HAVE_GETPEEREID */
+}
+
+#endif /* if UNIX_SOCK_SUPPORT */
diff --git a/src/openvpn/socket.h b/src/openvpn/socket.h
new file mode 100644
index 0000000..80e8128
--- /dev/null
+++ b/src/openvpn/socket.h
@@ -0,0 +1,1280 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef SOCKET_H
+#define SOCKET_H
+
+#include "buffer.h"
+#include "common.h"
+#include "error.h"
+#include "proto.h"
+#include "mtu.h"
+#include "win32.h"
+#include "event.h"
+#include "proxy.h"
+#include "socks.h"
+#include "misc.h"
+
+/*
+ * OpenVPN's default port number as assigned by IANA.
+ */
+#define OPENVPN_PORT "1194"
+
+/*
+ * Number of seconds that "resolv-retry infinite"
+ * represents.
+ */
+#define RESOLV_RETRY_INFINITE 1000000000
+
+/*
+ * packet_size_type is used to communicate packet size
+ * over the wire when stream oriented protocols are
+ * being used
+ */
+
+typedef uint16_t packet_size_type;
+
+/* convert a packet_size_type from host to network order */
+#define htonps(x) htons(x)
+
+/* convert a packet_size_type from network to host order */
+#define ntohps(x) ntohs(x)
+
+/* OpenVPN sockaddr struct */
+struct openvpn_sockaddr
+{
+    /*int dummy;*/ /* add offset to force a bug if sa not explicitly dereferenced */
+    union {
+        struct sockaddr sa;
+        struct sockaddr_in in4;
+        struct sockaddr_in6 in6;
+    } addr;
+};
+
+/* struct to hold preresolved host names */
+struct cached_dns_entry {
+    const char *hostname;
+    const char *servname;
+    int ai_family;
+    int flags;
+    struct addrinfo *ai;
+    struct cached_dns_entry *next;
+};
+
+/* actual address of remote, based on source address of received packets */
+struct link_socket_actual
+{
+    /*int dummy;*/ /* add offset to force a bug if dest not explicitly dereferenced */
+
+    struct openvpn_sockaddr dest;
+#if ENABLE_IP_PKTINFO
+    union {
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+        struct in_pktinfo in4;
+#elif defined(IP_RECVDSTADDR)
+        struct in_addr in4;
+#endif
+        struct in6_pktinfo in6;
+    } pi;
+#endif
+};
+
+/* IP addresses which are persistant across SIGUSR1s */
+struct link_socket_addr
+{
+    struct addrinfo *bind_local;
+    struct addrinfo *remote_list; /* complete remote list */
+    struct addrinfo *current_remote; /* remote used in the
+                                      * current connection attempt */
+    struct link_socket_actual actual; /* reply to this address */
+};
+
+struct link_socket_info
+{
+    struct link_socket_addr *lsa;
+    bool connection_established;
+    const char *ipchange_command;
+    const struct plugin_list *plugins;
+    bool remote_float;
+    int proto;                  /* Protocol (PROTO_x defined below) */
+    sa_family_t af;                     /* Address family like AF_INET, AF_INET6 or AF_UNSPEC*/
+    bool bind_ipv6_only;
+    int mtu_changed;            /* Set to true when mtu value is changed */
+};
+
+/*
+ * Used to extract packets encapsulated in streams into a buffer,
+ * in this case IP packets embedded in a TCP stream.
+ */
+struct stream_buf
+{
+    struct buffer buf_init;
+    struct buffer residual;
+    int maxlen;
+    bool residual_fully_formed;
+
+    struct buffer buf;
+    struct buffer next;
+    int len;   /* -1 if not yet known */
+
+    bool error; /* if true, fatal TCP error has occurred,
+                *  requiring that connection be restarted */
+#if PORT_SHARE
+#define PS_DISABLED 0
+#define PS_ENABLED  1
+#define PS_FOREIGN  2
+    int port_share_state;
+#endif
+};
+
+/*
+ * Used to set socket buffer sizes
+ */
+struct socket_buffer_size
+{
+    int rcvbuf;
+    int sndbuf;
+};
+
+/*
+ * This is the main socket structure used by OpenVPN.  The SOCKET_
+ * defines try to abstract away our implementation differences between
+ * using sockets on Posix vs. Win32.
+ */
+struct link_socket
+{
+    struct link_socket_info info;
+
+    socket_descriptor_t sd;
+    socket_descriptor_t ctrl_sd; /* only used for UDP over Socks */
+
+#ifdef _WIN32
+    struct overlapped_io reads;
+    struct overlapped_io writes;
+    struct rw_handle rw_handle;
+    struct rw_handle listen_handle; /* For listening on TCP socket in server mode */
+#endif
+
+    /* used for printing status info only */
+    unsigned int rwflags_debug;
+
+    /* used for long-term queueing of pre-accepted socket listen */
+    bool listen_persistent_queued;
+
+    const char *remote_host;
+    const char *remote_port;
+    const char *local_host;
+    const char *local_port;
+    struct cached_dns_entry *dns_cache;
+    bool bind_local;
+
+#define INETD_NONE   0
+#define INETD_WAIT   1
+#define INETD_NOWAIT 2
+    int inetd;
+
+#define LS_MODE_DEFAULT           0
+#define LS_MODE_TCP_LISTEN        1
+#define LS_MODE_TCP_ACCEPT_FROM   2
+    int mode;
+
+    int resolve_retry_seconds;
+    int mtu_discover_type;
+
+    struct socket_buffer_size socket_buffer_sizes;
+
+    int mtu;                    /* OS discovered MTU, or 0 if unknown */
+
+#define SF_USE_IP_PKTINFO (1<<0)
+#define SF_TCP_NODELAY (1<<1)
+#define SF_PORT_SHARE (1<<2)
+#define SF_HOST_RANDOMIZE (1<<3)
+#define SF_GETADDRINFO_DGRAM (1<<4)
+    unsigned int sockflags;
+    int mark;
+
+    /* for stream sockets */
+    struct stream_buf stream_buf;
+    struct buffer stream_buf_data;
+    bool stream_reset;
+
+    /* HTTP proxy */
+    struct http_proxy_info *http_proxy;
+
+    /* Socks proxy */
+    struct socks_proxy_info *socks_proxy;
+    struct link_socket_actual socks_relay; /* Socks UDP relay address */
+
+    /* The OpenVPN server we will use the proxy to connect to */
+    const char *proxy_dest_host;
+    const char *proxy_dest_port;
+
+    /* Pointer to the server-poll to trigger the timeout in function which have
+     * their own loop instead of using the main oop */
+    struct event_timeout *server_poll_timeout;
+
+#if PASSTOS_CAPABILITY
+    /* used to get/set TOS. */
+#if defined(TARGET_LINUX)
+    uint8_t ptos;
+#else /* all the BSDs, Solaris, MacOS use plain "int" -> see "man ip" there */
+    int ptos;
+#endif
+    bool ptos_defined;
+#endif
+
+#ifdef ENABLE_DEBUG
+    int gremlin; /* --gremlin bits */
+#endif
+};
+
+/*
+ * Some Posix/Win32 differences.
+ */
+
+#ifndef MSG_NOSIGNAL
+#define MSG_NOSIGNAL 0
+#endif
+
+#ifdef _WIN32
+
+#define openvpn_close_socket(s) closesocket(s)
+
+int socket_recv_queue(struct link_socket *sock, int maxsize);
+
+int socket_send_queue(struct link_socket *sock,
+                      struct buffer *buf,
+                      const struct link_socket_actual *to);
+
+int socket_finalize(
+    SOCKET s,
+    struct overlapped_io *io,
+    struct buffer *buf,
+    struct link_socket_actual *from);
+
+#else  /* ifdef _WIN32 */
+
+#define openvpn_close_socket(s) close(s)
+
+#endif
+
+struct link_socket *link_socket_new(void);
+
+void socket_bind(socket_descriptor_t sd,
+                 struct addrinfo *local,
+                 int af_family,
+                 const char *prefix,
+                 bool ipv6only);
+
+int openvpn_connect(socket_descriptor_t sd,
+                    const struct sockaddr *remote,
+                    int connect_timeout,
+                    volatile int *signal_received);
+
+
+
+/*
+ * Initialize link_socket object.
+ */
+
+void
+link_socket_init_phase1(struct link_socket *sock,
+                        const char *local_host,
+                        const char *local_port,
+                        const char *remote_host,
+                        const char *remote_port,
+                        struct cached_dns_entry *dns_cache,
+                        int proto,
+                        sa_family_t af,
+                        bool bind_ipv6_only,
+                        int mode,
+                        const struct link_socket *accept_from,
+                        struct http_proxy_info *http_proxy,
+                        struct socks_proxy_info *socks_proxy,
+#ifdef ENABLE_DEBUG
+                        int gremlin,
+#endif
+                        bool bind_local,
+                        bool remote_float,
+                        int inetd,
+                        struct link_socket_addr *lsa,
+                        const char *ipchange_command,
+                        const struct plugin_list *plugins,
+                        int resolve_retry_seconds,
+                        int mtu_discover_type,
+                        int rcvbuf,
+                        int sndbuf,
+                        int mark,
+                        struct event_timeout *server_poll_timeout,
+                        unsigned int sockflags);
+
+void link_socket_init_phase2(struct link_socket *sock,
+                             const struct frame *frame,
+                             struct signal_info *sig_info);
+
+void do_preresolve(struct context *c);
+
+void socket_adjust_frame_parameters(struct frame *frame, int proto);
+
+void frame_adjust_path_mtu(struct frame *frame, int pmtu, int proto);
+
+void link_socket_close(struct link_socket *sock);
+
+void sd_close(socket_descriptor_t *sd);
+
+#define PS_SHOW_PORT_IF_DEFINED (1<<0)
+#define PS_SHOW_PORT            (1<<1)
+#define PS_SHOW_PKTINFO         (1<<2)
+#define PS_DONT_SHOW_ADDR       (1<<3)
+#define PS_DONT_SHOW_FAMILY     (1<<4)
+
+const char *print_sockaddr_ex(const struct sockaddr *addr,
+                              const char *separator,
+                              const unsigned int flags,
+                              struct gc_arena *gc);
+
+static inline
+const char *
+print_openvpn_sockaddr_ex(const struct openvpn_sockaddr *addr,
+                          const char *separator,
+                          const unsigned int flags,
+                          struct gc_arena *gc)
+{
+    return print_sockaddr_ex(&addr->addr.sa, separator, flags, gc);
+}
+
+static inline
+const char *
+print_openvpn_sockaddr(const struct openvpn_sockaddr *addr,
+                       struct gc_arena *gc)
+{
+    return print_sockaddr_ex(&addr->addr.sa, ":", PS_SHOW_PORT, gc);
+}
+
+static inline
+const char *
+print_sockaddr(const struct sockaddr *addr,
+               struct gc_arena *gc)
+{
+    return print_sockaddr_ex(addr, ":", PS_SHOW_PORT, gc);
+}
+
+
+
+const char *print_link_socket_actual_ex(const struct link_socket_actual *act,
+                                        const char *separator,
+                                        const unsigned int flags,
+                                        struct gc_arena *gc);
+
+const char *print_link_socket_actual(const struct link_socket_actual *act,
+                                     struct gc_arena *gc);
+
+
+#define IA_EMPTY_IF_UNDEF (1<<0)
+#define IA_NET_ORDER      (1<<1)
+const char *print_in_addr_t(in_addr_t addr, unsigned int flags, struct gc_arena *gc);
+
+const char *print_in6_addr(struct in6_addr addr6, unsigned int flags, struct gc_arena *gc);
+
+struct in6_addr add_in6_addr( struct in6_addr base, uint32_t add );
+
+#define SA_IP_PORT        (1<<0)
+#define SA_SET_IF_NONZERO (1<<1)
+void setenv_sockaddr(struct env_set *es,
+                     const char *name_prefix,
+                     const struct openvpn_sockaddr *addr,
+                     const unsigned int flags);
+
+void setenv_in_addr_t(struct env_set *es,
+                      const char *name_prefix,
+                      in_addr_t addr,
+                      const unsigned int flags);
+
+void setenv_in6_addr(struct env_set *es,
+                     const char *name_prefix,
+                     const struct in6_addr *addr,
+                     const unsigned int flags);
+
+void setenv_link_socket_actual(struct env_set *es,
+                               const char *name_prefix,
+                               const struct link_socket_actual *act,
+                               const unsigned int flags);
+
+void bad_address_length(int actual, int expected);
+
+/* IPV4_INVALID_ADDR: returned by link_socket_current_remote()
+ * to ease redirect-gateway logic for ipv4 tunnels on ipv6 endpoints
+ */
+#define IPV4_INVALID_ADDR 0xffffffff
+in_addr_t link_socket_current_remote(const struct link_socket_info *info);
+
+const struct in6_addr *link_socket_current_remote_ipv6
+    (const struct link_socket_info *info);
+
+void link_socket_connection_initiated(const struct buffer *buf,
+                                      struct link_socket_info *info,
+                                      const struct link_socket_actual *addr,
+                                      const char *common_name,
+                                      struct env_set *es);
+
+void link_socket_bad_incoming_addr(struct buffer *buf,
+                                   const struct link_socket_info *info,
+                                   const struct link_socket_actual *from_addr);
+
+void set_actual_address(struct link_socket_actual *actual,
+                        struct addrinfo *ai);
+
+void link_socket_bad_outgoing_addr(void);
+
+void setenv_trusted(struct env_set *es, const struct link_socket_info *info);
+
+bool link_socket_update_flags(struct link_socket *ls, unsigned int sockflags);
+
+void link_socket_update_buffer_sizes(struct link_socket *ls, int rcvbuf, int sndbuf);
+
+/*
+ * Low-level functions
+ */
+
+/* return values of openvpn_inet_aton */
+#define OIA_HOSTNAME   0
+#define OIA_IP         1
+#define OIA_ERROR     -1
+int openvpn_inet_aton(const char *dotted_quad, struct in_addr *addr);
+
+/* integrity validation on pulled options */
+bool ip_addr_dotted_quad_safe(const char *dotted_quad);
+
+bool ip_or_dns_addr_safe(const char *addr, const bool allow_fqdn);
+
+bool mac_addr_safe(const char *mac_addr);
+
+bool ipv6_addr_safe(const char *ipv6_text_addr);
+
+socket_descriptor_t create_socket_tcp(struct addrinfo *);
+
+socket_descriptor_t socket_do_accept(socket_descriptor_t sd,
+                                     struct link_socket_actual *act,
+                                     const bool nowait);
+
+/*
+ * proto related
+ */
+bool proto_is_net(int proto);
+
+bool proto_is_dgram(int proto);
+
+bool proto_is_udp(int proto);
+
+bool proto_is_tcp(int proto);
+
+
+#if UNIX_SOCK_SUPPORT
+
+socket_descriptor_t create_socket_unix(void);
+
+void socket_bind_unix(socket_descriptor_t sd,
+                      struct sockaddr_un *local,
+                      const char *prefix);
+
+socket_descriptor_t socket_accept_unix(socket_descriptor_t sd,
+                                       struct sockaddr_un *remote);
+
+int socket_connect_unix(socket_descriptor_t sd,
+                        struct sockaddr_un *remote);
+
+void sockaddr_unix_init(struct sockaddr_un *local, const char *path);
+
+const char *sockaddr_unix_name(const struct sockaddr_un *local, const char *null);
+
+void socket_delete_unix(const struct sockaddr_un *local);
+
+bool unix_socket_get_peer_uid_gid(const socket_descriptor_t sd, int *uid, int *gid);
+
+#endif /* if UNIX_SOCK_SUPPORT */
+
+/*
+ * DNS resolution
+ */
+
+#define GETADDR_RESOLVE               (1<<0)
+#define GETADDR_FATAL                 (1<<1)
+#define GETADDR_HOST_ORDER            (1<<2)
+#define GETADDR_MENTION_RESOLVE_RETRY (1<<3)
+#define GETADDR_FATAL_ON_SIGNAL       (1<<4)
+#define GETADDR_WARN_ON_SIGNAL        (1<<5)
+#define GETADDR_MSG_VIRT_OUT          (1<<6)
+#define GETADDR_TRY_ONCE              (1<<7)
+#define GETADDR_UPDATE_MANAGEMENT_STATE (1<<8)
+#define GETADDR_RANDOMIZE             (1<<9)
+#define GETADDR_PASSIVE               (1<<10)
+#define GETADDR_DATAGRAM              (1<<11)
+
+#define GETADDR_CACHE_MASK              (GETADDR_DATAGRAM|GETADDR_PASSIVE)
+
+/**
+ * Translate an IPv4 addr or hostname from string form to in_addr_t
+ *
+ * In case of resolve error, it will try again for
+ * resolve_retry_seconds seconds.
+ */
+in_addr_t getaddr(unsigned int flags,
+                  const char *hostname,
+                  int resolve_retry_seconds,
+                  bool *succeeded,
+                  volatile int *signal_received);
+
+/**
+ * Translate an IPv6 addr or hostname from string form to in6_addr
+ */
+bool get_ipv6_addr(const char *hostname, struct in6_addr *network,
+                   unsigned int *netbits, int msglevel);
+
+int openvpn_getaddrinfo(unsigned int flags,
+                        const char *hostname,
+                        const char *servname,
+                        int resolve_retry_seconds,
+                        volatile int *signal_received,
+                        int ai_family,
+                        struct addrinfo **res);
+
+/*
+ * Transport protocol naming and other details.
+ */
+
+/*
+ * Use enum's instead of #define to allow for easier
+ * optional proto support
+ */
+enum proto_num {
+    PROTO_NONE,     /* catch for uninitialized */
+    PROTO_UDP,
+    PROTO_TCP,
+    PROTO_TCP_SERVER,
+    PROTO_TCP_CLIENT,
+    PROTO_N
+};
+
+int ascii2proto(const char *proto_name);
+
+sa_family_t ascii2af(const char *proto_name);
+
+const char *proto2ascii(int proto, sa_family_t af, bool display_form);
+
+const char *proto2ascii_all(struct gc_arena *gc);
+
+const char *proto_remote(int proto, bool remote);
+
+const char *addr_family_name(int af);
+
+/*
+ * Overhead added to packets by various protocols.
+ */
+#define IPv4_UDP_HEADER_SIZE              28
+#define IPv4_TCP_HEADER_SIZE              40
+#define IPv6_UDP_HEADER_SIZE              48
+#define IPv6_TCP_HEADER_SIZE              60
+
+extern const int proto_overhead[];
+
+static inline int
+datagram_overhead(int proto)
+{
+    ASSERT(proto >= 0 && proto < PROTO_N);
+    return proto_overhead [proto];
+}
+
+/*
+ * Misc inline functions
+ */
+
+static inline bool
+link_socket_proto_connection_oriented(int proto)
+{
+    return !proto_is_dgram(proto);
+}
+
+static inline bool
+link_socket_connection_oriented(const struct link_socket *sock)
+{
+    if (sock)
+    {
+        return link_socket_proto_connection_oriented(sock->info.proto);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static inline bool
+addr_defined(const struct openvpn_sockaddr *addr)
+{
+    if (!addr)
+    {
+        return 0;
+    }
+    switch (addr->addr.sa.sa_family)
+    {
+        case AF_INET: return addr->addr.in4.sin_addr.s_addr != 0;
+
+        case AF_INET6: return !IN6_IS_ADDR_UNSPECIFIED(&addr->addr.in6.sin6_addr);
+
+        default: return 0;
+    }
+}
+
+static inline bool
+addr_local(const struct sockaddr *addr)
+{
+    if (!addr)
+    {
+        return false;
+    }
+    switch (addr->sa_family)
+    {
+        case AF_INET:
+            return ((const struct sockaddr_in *)addr)->sin_addr.s_addr == htonl(INADDR_LOOPBACK);
+
+        case AF_INET6:
+            return IN6_IS_ADDR_LOOPBACK(&((const struct sockaddr_in6 *)addr)->sin6_addr);
+
+        default:
+            return false;
+    }
+}
+
+
+static inline bool
+addr_defined_ipi(const struct link_socket_actual *lsa)
+{
+#if ENABLE_IP_PKTINFO
+    if (!lsa)
+    {
+        return 0;
+    }
+    switch (lsa->dest.addr.sa.sa_family)
+    {
+#if defined(HAVE_IN_PKTINFO) && defined(HAVE_IPI_SPEC_DST)
+        case AF_INET: return lsa->pi.in4.ipi_spec_dst.s_addr != 0;
+
+#elif defined(IP_RECVDSTADDR)
+        case AF_INET: return lsa->pi.in4.s_addr != 0;
+
+#endif
+        case AF_INET6: return !IN6_IS_ADDR_UNSPECIFIED(&lsa->pi.in6.ipi6_addr);
+
+        default: return 0;
+    }
+#else  /* if ENABLE_IP_PKTINFO */
+    ASSERT(0);
+#endif
+    return false;
+}
+
+static inline bool
+link_socket_actual_defined(const struct link_socket_actual *act)
+{
+    return act && addr_defined(&act->dest);
+}
+
+static inline bool
+addr_match(const struct openvpn_sockaddr *a1, const struct openvpn_sockaddr *a2)
+{
+    switch (a1->addr.sa.sa_family)
+    {
+        case AF_INET:
+            return a1->addr.in4.sin_addr.s_addr == a2->addr.in4.sin_addr.s_addr;
+
+        case AF_INET6:
+            return IN6_ARE_ADDR_EQUAL(&a1->addr.in6.sin6_addr, &a2->addr.in6.sin6_addr);
+    }
+    ASSERT(0);
+    return false;
+}
+
+static inline bool
+addrlist_match(const struct openvpn_sockaddr *a1, const struct addrinfo *addrlist)
+{
+    const struct addrinfo *curele;
+    for (curele = addrlist; curele; curele = curele->ai_next)
+    {
+        switch (a1->addr.sa.sa_family)
+        {
+            case AF_INET:
+                if (a1->addr.in4.sin_addr.s_addr == ((struct sockaddr_in *)curele->ai_addr)->sin_addr.s_addr)
+                {
+                    return true;
+                }
+                break;
+
+            case AF_INET6:
+                if (IN6_ARE_ADDR_EQUAL(&a1->addr.in6.sin6_addr, &((struct sockaddr_in6 *) curele->ai_addr)->sin6_addr))
+                {
+                    return true;
+                }
+                break;
+
+            default:
+                ASSERT(0);
+        }
+    }
+    return false;
+}
+
+static inline in_addr_t
+addr_host(const struct openvpn_sockaddr *addr)
+{
+    /*
+     * "public" addr returned is checked against ifconfig for
+     * possible clash: non sense for now given
+     * that we do ifconfig only IPv4
+     */
+    if (addr->addr.sa.sa_family != AF_INET)
+    {
+        return 0;
+    }
+    return ntohl(addr->addr.in4.sin_addr.s_addr);
+}
+
+
+static inline bool
+addrlist_port_match(const struct openvpn_sockaddr *a1, const struct addrinfo *a2)
+{
+    const struct addrinfo *curele;
+    for (curele = a2; curele; curele = curele->ai_next)
+    {
+        switch (a1->addr.sa.sa_family)
+        {
+            case AF_INET:
+                if (curele->ai_family == AF_INET
+                    && a1->addr.in4.sin_addr.s_addr == ((struct sockaddr_in *)curele->ai_addr)->sin_addr.s_addr
+                    && a1->addr.in4.sin_port == ((struct sockaddr_in *)curele->ai_addr)->sin_port)
+                {
+                    return true;
+                }
+                break;
+
+            case AF_INET6:
+                if (curele->ai_family == AF_INET6
+                    && IN6_ARE_ADDR_EQUAL(&a1->addr.in6.sin6_addr, &((struct sockaddr_in6 *) curele->ai_addr)->sin6_addr)
+                    && a1->addr.in6.sin6_port == ((struct sockaddr_in6 *) curele->ai_addr)->sin6_port)
+                {
+                    return true;
+                }
+                break;
+
+            default:
+                ASSERT(0);
+        }
+    }
+    return false;
+}
+
+
+
+static inline bool
+addr_port_match(const struct openvpn_sockaddr *a1, const struct openvpn_sockaddr *a2)
+{
+    switch (a1->addr.sa.sa_family)
+    {
+        case AF_INET:
+            return a1->addr.in4.sin_addr.s_addr == a2->addr.in4.sin_addr.s_addr
+                   && a1->addr.in4.sin_port == a2->addr.in4.sin_port;
+
+        case AF_INET6:
+            return IN6_ARE_ADDR_EQUAL(&a1->addr.in6.sin6_addr, &a2->addr.in6.sin6_addr)
+                   && a1->addr.in6.sin6_port == a2->addr.in6.sin6_port;
+    }
+    ASSERT(0);
+    return false;
+}
+
+static inline bool
+addr_match_proto(const struct openvpn_sockaddr *a1,
+                 const struct openvpn_sockaddr *a2,
+                 const int proto)
+{
+    return link_socket_proto_connection_oriented(proto)
+           ? addr_match(a1, a2)
+           : addr_port_match(a1, a2);
+}
+
+
+static inline bool
+addrlist_match_proto(const struct openvpn_sockaddr *a1,
+                     struct addrinfo *addr_list,
+                     const int proto)
+{
+    return link_socket_proto_connection_oriented(proto)
+           ? addrlist_match(a1, addr_list)
+           : addrlist_port_match(a1, addr_list);
+}
+
+static inline void
+addr_zero_host(struct openvpn_sockaddr *addr)
+{
+    switch (addr->addr.sa.sa_family)
+    {
+        case AF_INET:
+            addr->addr.in4.sin_addr.s_addr = 0;
+            break;
+
+        case AF_INET6:
+            memset(&addr->addr.in6.sin6_addr, 0, sizeof(struct in6_addr));
+            break;
+    }
+}
+
+static inline void
+addr_copy_sa(struct openvpn_sockaddr *dst, const struct openvpn_sockaddr *src)
+{
+    dst->addr = src->addr;
+}
+
+static inline bool
+addr_inet4or6(struct sockaddr *addr)
+{
+    return addr->sa_family == AF_INET || addr->sa_family == AF_INET6;
+}
+
+int addr_guess_family(sa_family_t af,const char *name);
+
+static inline int
+af_addr_size(sa_family_t af)
+{
+    switch (af)
+    {
+        case AF_INET: return sizeof(struct sockaddr_in);
+
+        case AF_INET6: return sizeof(struct sockaddr_in6);
+
+        default:
+#if 0
+            /* could be called from socket_do_accept() with empty addr */
+            msg(M_ERR, "Bad address family: %d\n", af);
+            ASSERT(0);
+#endif
+            return 0;
+    }
+}
+
+static inline bool
+link_socket_actual_match(const struct link_socket_actual *a1, const struct link_socket_actual *a2)
+{
+    return addr_port_match(&a1->dest, &a2->dest);
+}
+
+#if PORT_SHARE
+
+static inline bool
+socket_foreign_protocol_detected(const struct link_socket *sock)
+{
+    return link_socket_connection_oriented(sock)
+           && sock->stream_buf.port_share_state == PS_FOREIGN;
+}
+
+static inline const struct buffer *
+socket_foreign_protocol_head(const struct link_socket *sock)
+{
+    return &sock->stream_buf.buf;
+}
+
+static inline int
+socket_foreign_protocol_sd(const struct link_socket *sock)
+{
+    return sock->sd;
+}
+
+#endif /* if PORT_SHARE */
+
+static inline bool
+socket_connection_reset(const struct link_socket *sock, int status)
+{
+    if (link_socket_connection_oriented(sock))
+    {
+        if (sock->stream_reset || sock->stream_buf.error)
+        {
+            return true;
+        }
+        else if (status < 0)
+        {
+            const int err = openvpn_errno();
+#ifdef _WIN32
+            return err == WSAECONNRESET || err == WSAECONNABORTED;
+#else
+            return err == ECONNRESET;
+#endif
+        }
+    }
+    return false;
+}
+
+static inline bool
+link_socket_verify_incoming_addr(struct buffer *buf,
+                                 const struct link_socket_info *info,
+                                 const struct link_socket_actual *from_addr)
+{
+    if (buf->len > 0)
+    {
+        switch (from_addr->dest.addr.sa.sa_family)
+        {
+            case AF_INET6:
+            case AF_INET:
+                if (!link_socket_actual_defined(from_addr))
+                {
+                    return false;
+                }
+                if (info->remote_float || (!info->lsa->remote_list))
+                {
+                    return true;
+                }
+                if (addrlist_match_proto(&from_addr->dest, info->lsa->remote_list, info->proto))
+                {
+                    return true;
+                }
+        }
+    }
+    return false;
+}
+
+static inline void
+link_socket_get_outgoing_addr(struct buffer *buf,
+                              const struct link_socket_info *info,
+                              struct link_socket_actual **act)
+{
+    if (buf->len > 0)
+    {
+        struct link_socket_addr *lsa = info->lsa;
+        if (link_socket_actual_defined(&lsa->actual))
+        {
+            *act = &lsa->actual;
+        }
+        else
+        {
+            link_socket_bad_outgoing_addr();
+            buf->len = 0;
+            *act = NULL;
+        }
+    }
+}
+
+static inline void
+link_socket_set_outgoing_addr(const struct buffer *buf,
+                              struct link_socket_info *info,
+                              const struct link_socket_actual *act,
+                              const char *common_name,
+                              struct env_set *es)
+{
+    if (!buf || buf->len > 0)
+    {
+        struct link_socket_addr *lsa = info->lsa;
+        if (
+            /* new or changed address? */
+            (!info->connection_established
+             || !addr_match_proto(&act->dest, &lsa->actual.dest, info->proto)
+            )
+            &&
+            /* address undef or address == remote or --float */
+            (info->remote_float
+             || (!lsa->remote_list || addrlist_match_proto(&act->dest, lsa->remote_list, info->proto))
+            )
+            )
+        {
+            link_socket_connection_initiated(buf, info, act, common_name, es);
+        }
+    }
+}
+
+/*
+ * Stream buffer handling -- stream_buf is a helper class
+ * to assist in the packetization of stream transport protocols
+ * such as TCP.
+ */
+
+void stream_buf_init(struct stream_buf *sb,
+                     struct buffer *buf,
+                     const unsigned int sockflags,
+                     const int proto);
+
+void stream_buf_close(struct stream_buf *sb);
+
+bool stream_buf_added(struct stream_buf *sb, int length_added);
+
+static inline bool
+stream_buf_read_setup(struct link_socket *sock)
+{
+    bool stream_buf_read_setup_dowork(struct link_socket *sock);
+
+    if (link_socket_connection_oriented(sock))
+    {
+        return stream_buf_read_setup_dowork(sock);
+    }
+    else
+    {
+        return true;
+    }
+}
+
+/*
+ * Socket Read Routines
+ */
+
+int link_socket_read_tcp(struct link_socket *sock,
+                         struct buffer *buf);
+
+#ifdef _WIN32
+
+static inline int
+link_socket_read_udp_win32(struct link_socket *sock,
+                           struct buffer *buf,
+                           struct link_socket_actual *from)
+{
+    return socket_finalize(sock->sd, &sock->reads, buf, from);
+}
+
+#else  /* ifdef _WIN32 */
+
+int link_socket_read_udp_posix(struct link_socket *sock,
+                               struct buffer *buf,
+                               struct link_socket_actual *from);
+
+#endif
+
+/* read a TCP or UDP packet from link */
+static inline int
+link_socket_read(struct link_socket *sock,
+                 struct buffer *buf,
+                 struct link_socket_actual *from)
+{
+    if (proto_is_udp(sock->info.proto)) /* unified UDPv4 and UDPv6 */
+    {
+        int res;
+
+#ifdef _WIN32
+        res = link_socket_read_udp_win32(sock, buf, from);
+#else
+        res = link_socket_read_udp_posix(sock, buf, from);
+#endif
+        return res;
+    }
+    else if (proto_is_tcp(sock->info.proto)) /* unified TCPv4 and TCPv6 */
+    {
+        /* from address was returned by accept */
+        addr_copy_sa(&from->dest, &sock->info.lsa->actual.dest);
+        return link_socket_read_tcp(sock, buf);
+    }
+    else
+    {
+        ASSERT(0);
+        return -1; /* NOTREACHED */
+    }
+}
+
+/*
+ * Socket Write routines
+ */
+
+int link_socket_write_tcp(struct link_socket *sock,
+                          struct buffer *buf,
+                          struct link_socket_actual *to);
+
+#ifdef _WIN32
+
+static inline int
+link_socket_write_win32(struct link_socket *sock,
+                        struct buffer *buf,
+                        struct link_socket_actual *to)
+{
+    int err = 0;
+    int status = 0;
+    if (overlapped_io_active(&sock->writes))
+    {
+        status = socket_finalize(sock->sd, &sock->writes, NULL, NULL);
+        if (status < 0)
+        {
+            err = WSAGetLastError();
+        }
+    }
+    socket_send_queue(sock, buf, to);
+    if (status < 0)
+    {
+        WSASetLastError(err);
+        return status;
+    }
+    else
+    {
+        return BLEN(buf);
+    }
+}
+
+#else  /* ifdef _WIN32 */
+
+static inline size_t
+link_socket_write_udp_posix(struct link_socket *sock,
+                            struct buffer *buf,
+                            struct link_socket_actual *to)
+{
+#if ENABLE_IP_PKTINFO
+    size_t link_socket_write_udp_posix_sendmsg(struct link_socket *sock,
+                                               struct buffer *buf,
+                                               struct link_socket_actual *to);
+
+    if (proto_is_udp(sock->info.proto) && (sock->sockflags & SF_USE_IP_PKTINFO)
+        && addr_defined_ipi(to))
+    {
+        return link_socket_write_udp_posix_sendmsg(sock, buf, to);
+    }
+    else
+#endif
+    return sendto(sock->sd, BPTR(buf), BLEN(buf), 0,
+                  (struct sockaddr *) &to->dest.addr.sa,
+                  (socklen_t) af_addr_size(to->dest.addr.sa.sa_family));
+}
+
+static inline size_t
+link_socket_write_tcp_posix(struct link_socket *sock,
+                            struct buffer *buf,
+                            struct link_socket_actual *to)
+{
+    return send(sock->sd, BPTR(buf), BLEN(buf), MSG_NOSIGNAL);
+}
+
+#endif /* ifdef _WIN32 */
+
+static inline size_t
+link_socket_write_udp(struct link_socket *sock,
+                      struct buffer *buf,
+                      struct link_socket_actual *to)
+{
+#ifdef _WIN32
+    return link_socket_write_win32(sock, buf, to);
+#else
+    return link_socket_write_udp_posix(sock, buf, to);
+#endif
+}
+
+/* write a TCP or UDP packet to link */
+static inline int
+link_socket_write(struct link_socket *sock,
+                  struct buffer *buf,
+                  struct link_socket_actual *to)
+{
+    if (proto_is_udp(sock->info.proto)) /* unified UDPv4 and UDPv6 */
+    {
+        return link_socket_write_udp(sock, buf, to);
+    }
+    else if (proto_is_tcp(sock->info.proto)) /* unified TCPv4 and TCPv6 */
+    {
+        return link_socket_write_tcp(sock, buf, to);
+    }
+    else
+    {
+        ASSERT(0);
+        return -1; /* NOTREACHED */
+    }
+}
+
+#if PASSTOS_CAPABILITY
+
+/*
+ * Extract TOS bits.  Assumes that ipbuf is a valid IPv4 packet.
+ */
+static inline void
+link_socket_extract_tos(struct link_socket *ls, const struct buffer *ipbuf)
+{
+    if (ls && ipbuf)
+    {
+        struct openvpn_iphdr *iph = (struct openvpn_iphdr *) BPTR(ipbuf);
+        ls->ptos = iph->tos;
+        ls->ptos_defined = true;
+    }
+}
+
+/*
+ * Set socket properties to reflect TOS bits which were extracted
+ * from tunnel packet.
+ */
+static inline void
+link_socket_set_tos(struct link_socket *ls)
+{
+    if (ls && ls->ptos_defined)
+    {
+        setsockopt(ls->sd, IPPROTO_IP, IP_TOS, (const void *)&ls->ptos, sizeof(ls->ptos));
+    }
+}
+
+#endif /* if PASSTOS_CAPABILITY */
+
+/*
+ * Socket I/O wait functions
+ */
+
+static inline bool
+socket_read_residual(const struct link_socket *s)
+{
+    return s && s->stream_buf.residual_fully_formed;
+}
+
+static inline event_t
+socket_event_handle(const struct link_socket *s)
+{
+#ifdef _WIN32
+    return &s->rw_handle;
+#else
+    return s->sd;
+#endif
+}
+
+event_t socket_listen_event_handle(struct link_socket *s);
+
+unsigned int
+socket_set(struct link_socket *s,
+           struct event_set *es,
+           unsigned int rwflags,
+           void *arg,
+           unsigned int *persistent);
+
+static inline void
+socket_set_listen_persistent(struct link_socket *s,
+                             struct event_set *es,
+                             void *arg)
+{
+    if (s && !s->listen_persistent_queued)
+    {
+        event_ctl(es, socket_listen_event_handle(s), EVENT_READ, arg);
+        s->listen_persistent_queued = true;
+    }
+}
+
+static inline void
+socket_reset_listen_persistent(struct link_socket *s)
+{
+#ifdef _WIN32
+    reset_net_event_win32(&s->listen_handle, s->sd);
+#endif
+}
+
+const char *socket_stat(const struct link_socket *s, unsigned int rwflags, struct gc_arena *gc);
+
+#endif /* SOCKET_H */
diff --git a/src/openvpn/socks.c b/src/openvpn/socks.c
new file mode 100644
index 0000000..57f0cee
--- /dev/null
+++ b/src/openvpn/socks.c
@@ -0,0 +1,619 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * 2004-01-30: Added Socks5 proxy support, see RFC 1928
+ *   (Christof Meerwald, http://cmeerw.org)
+ *
+ * 2010-10-10: Added Socks5 plain text authentication support (RFC 1929)
+ *   (Pierre Bourdon <delroth@gmail.com>)
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "common.h"
+#include "misc.h"
+#include "win32.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "misc.h"
+#include "proxy.h"
+
+#include "memdbg.h"
+
+#define UP_TYPE_SOCKS           "SOCKS Proxy"
+
+void
+socks_adjust_frame_parameters(struct frame *frame, int proto)
+{
+    if (proto == PROTO_UDP)
+    {
+        frame_add_to_extra_link(frame, 10);
+    }
+}
+
+struct socks_proxy_info *
+socks_proxy_new(const char *server,
+                const char *port,
+                const char *authfile)
+{
+    struct socks_proxy_info *p;
+
+    ALLOC_OBJ_CLEAR(p, struct socks_proxy_info);
+
+    ASSERT(server);
+    ASSERT(port);
+
+    strncpynt(p->server, server, sizeof(p->server));
+    p->port = port;
+
+    if (authfile)
+    {
+        strncpynt(p->authfile, authfile, sizeof(p->authfile));
+    }
+    else
+    {
+        p->authfile[0] = 0;
+    }
+
+    p->defined = true;
+
+    return p;
+}
+
+void
+socks_proxy_close(struct socks_proxy_info *sp)
+{
+    free(sp);
+}
+
+static bool
+socks_username_password_auth(struct socks_proxy_info *p,
+                             socket_descriptor_t sd,
+                             volatile int *signal_received)
+{
+    char to_send[516];
+    char buf[2];
+    int len = 0;
+    const int timeout_sec = 5;
+    struct user_pass creds;
+    ssize_t size;
+
+    creds.defined = 0;
+    if (!get_user_pass(&creds, p->authfile, UP_TYPE_SOCKS, GET_USER_PASS_MANAGEMENT))
+    {
+        msg(M_NONFATAL, "SOCKS failed to get username/password.");
+        return false;
+    }
+
+    if ( (strlen(creds.username) > 255) || (strlen(creds.password) > 255) )
+    {
+        msg(M_NONFATAL,
+            "SOCKS username and/or password exceeds 255 characters.  "
+            "Authentication not possible.");
+        return false;
+    }
+    openvpn_snprintf(to_send, sizeof(to_send), "\x01%c%s%c%s", (int) strlen(creds.username),
+                     creds.username, (int) strlen(creds.password), creds.password);
+    size = send(sd, to_send, strlen(to_send), MSG_NOSIGNAL);
+
+    if (size != strlen(to_send))
+    {
+        msg(D_LINK_ERRORS | M_ERRNO, "socks_username_password_auth: TCP port write failed on send()");
+        return false;
+    }
+
+    while (len < 2)
+    {
+        int status;
+        ssize_t size;
+        fd_set reads;
+        struct timeval tv;
+        char c;
+
+        FD_ZERO(&reads);
+        openvpn_fd_set(sd, &reads);
+        tv.tv_sec = timeout_sec;
+        tv.tv_usec = 0;
+
+        status = select(sd + 1, &reads, NULL, NULL, &tv);
+
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            return false;
+        }
+
+        /* timeout? */
+        if (status == 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_username_password_auth: TCP port read timeout expired");
+            return false;
+        }
+
+        /* error */
+        if (status < 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_username_password_auth: TCP port read failed on select()");
+            return false;
+        }
+
+        /* read single char */
+        size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+        /* error? */
+        if (size != 1)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_username_password_auth: TCP port read failed on recv()");
+            return false;
+        }
+
+        /* store char in buffer */
+        buf[len++] = c;
+    }
+
+    /* VER = 5, SUCCESS = 0 --> auth success */
+    if (buf[0] != 5 && buf[1] != 0)
+    {
+        msg(D_LINK_ERRORS, "socks_username_password_auth: server refused the authentication");
+        return false;
+    }
+
+    return true;
+}
+
+static bool
+socks_handshake(struct socks_proxy_info *p,
+                socket_descriptor_t sd,
+                volatile int *signal_received)
+{
+    char buf[2];
+    int len = 0;
+    const int timeout_sec = 5;
+    ssize_t size;
+
+    /* VER = 5, NMETHODS = 1, METHODS = [0 (no auth)] */
+    char method_sel[3] = { 0x05, 0x01, 0x00 };
+    if (p->authfile[0])
+    {
+        method_sel[2] = 0x02; /* METHODS = [2 (plain login)] */
+
+    }
+    size = send(sd, method_sel, sizeof(method_sel), MSG_NOSIGNAL);
+    if (size != sizeof(method_sel))
+    {
+        msg(D_LINK_ERRORS | M_ERRNO, "socks_handshake: TCP port write failed on send()");
+        return false;
+    }
+
+    while (len < 2)
+    {
+        int status;
+        ssize_t size;
+        fd_set reads;
+        struct timeval tv;
+        char c;
+
+        FD_ZERO(&reads);
+        openvpn_fd_set(sd, &reads);
+        tv.tv_sec = timeout_sec;
+        tv.tv_usec = 0;
+
+        status = select(sd + 1, &reads, NULL, NULL, &tv);
+
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            return false;
+        }
+
+        /* timeout? */
+        if (status == 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_handshake: TCP port read timeout expired");
+            return false;
+        }
+
+        /* error */
+        if (status < 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_handshake: TCP port read failed on select()");
+            return false;
+        }
+
+        /* read single char */
+        size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+        /* error? */
+        if (size != 1)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "socks_handshake: TCP port read failed on recv()");
+            return false;
+        }
+
+        /* store char in buffer */
+        buf[len++] = c;
+    }
+
+    /* VER == 5 */
+    if (buf[0] != '\x05')
+    {
+        msg(D_LINK_ERRORS, "socks_handshake: Socks proxy returned bad status");
+        return false;
+    }
+
+    /* validate that the auth method returned is the one sent */
+    if (buf[1] != method_sel[2])
+    {
+        msg(D_LINK_ERRORS, "socks_handshake: Socks proxy returned unexpected auth");
+        return false;
+    }
+
+    /* select the appropriate authentication method */
+    switch (buf[1])
+    {
+        case 0: /* no authentication */
+            break;
+
+        case 2: /* login/password */
+            if (!p->authfile[0])
+            {
+                msg(D_LINK_ERRORS, "socks_handshake: server asked for username/login auth but we were "
+                    "not provided any credentials");
+                return false;
+            }
+
+            if (!socks_username_password_auth(p, sd, signal_received))
+            {
+                return false;
+            }
+
+            break;
+
+        default: /* unknown auth method */
+            msg(D_LINK_ERRORS, "socks_handshake: unknown SOCKS auth method");
+            return false;
+    }
+
+    return true;
+}
+
+static bool
+recv_socks_reply(socket_descriptor_t sd,
+                 struct openvpn_sockaddr *addr,
+                 volatile int *signal_received)
+{
+    char atyp = '\0';
+    int alen = 0;
+    int len = 0;
+    char buf[22];
+    const int timeout_sec = 5;
+
+    if (addr != NULL)
+    {
+        addr->addr.in4.sin_family = AF_INET;
+        addr->addr.in4.sin_addr.s_addr = htonl(INADDR_ANY);
+        addr->addr.in4.sin_port = htons(0);
+    }
+
+    while (len < 4 + alen + 2)
+    {
+        int status;
+        ssize_t size;
+        fd_set reads;
+        struct timeval tv;
+        char c;
+
+        FD_ZERO(&reads);
+        openvpn_fd_set(sd, &reads);
+        tv.tv_sec = timeout_sec;
+        tv.tv_usec = 0;
+
+        status = select(sd + 1, &reads, NULL, NULL, &tv);
+
+        get_signal(signal_received);
+        if (*signal_received)
+        {
+            return false;
+        }
+
+        /* timeout? */
+        if (status == 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "recv_socks_reply: TCP port read timeout expired");
+            return false;
+        }
+
+        /* error */
+        if (status < 0)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "recv_socks_reply: TCP port read failed on select()");
+            return false;
+        }
+
+        /* read single char */
+        size = recv(sd, &c, 1, MSG_NOSIGNAL);
+
+        /* error? */
+        if (size != 1)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "recv_socks_reply: TCP port read failed on recv()");
+            return false;
+        }
+
+        if (len == 3)
+        {
+            atyp = c;
+        }
+
+        if (len == 4)
+        {
+            switch (atyp)
+            {
+                case '\x01':    /* IP V4 */
+                    alen = 4;
+                    break;
+
+                case '\x03':    /* DOMAINNAME */
+                    alen = (unsigned char) c;
+                    break;
+
+                case '\x04':    /* IP V6 */
+                    alen = 16;
+                    break;
+
+                default:
+                    msg(D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad address type");
+                    return false;
+            }
+        }
+
+        /* store char in buffer */
+        if (len < (int)sizeof(buf))
+        {
+            buf[len] = c;
+        }
+        ++len;
+    }
+
+    /* VER == 5 && REP == 0 (succeeded) */
+    if (buf[0] != '\x05' || buf[1] != '\x00')
+    {
+        msg(D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad reply");
+        return false;
+    }
+
+    /* ATYP == 1 (IP V4 address) */
+    if (atyp == '\x01' && addr != NULL)
+    {
+        memcpy(&addr->addr.in4.sin_addr, buf + 4, sizeof(addr->addr.in4.sin_addr));
+        memcpy(&addr->addr.in4.sin_port, buf + 8, sizeof(addr->addr.in4.sin_port));
+        struct gc_arena gc = gc_new();
+        msg(M_INFO, "SOCKS proxy wants us to send UDP to %s",
+            print_openvpn_sockaddr(addr, &gc));
+        gc_free(&gc);
+    }
+
+
+    return true;
+}
+
+static int
+port_from_servname(const char *servname)
+{
+    int port = 0;
+    port = atoi(servname);
+    if (port >0 && port < 65536)
+    {
+        return port;
+    }
+
+    struct  servent *service;
+    service = getservbyname(servname, NULL);
+    if (service)
+    {
+        return service->s_port;
+    }
+
+    return 0;
+}
+
+void
+establish_socks_proxy_passthru(struct socks_proxy_info *p,
+                               socket_descriptor_t sd,  /* already open to proxy */
+                               const char *host,        /* openvpn server remote */
+                               const char *servname,    /* openvpn server port */
+                               volatile int *signal_received)
+{
+    char buf[128];
+    size_t len;
+
+    if (!socks_handshake(p, sd, signal_received))
+    {
+        goto error;
+    }
+
+    /* format Socks CONNECT message */
+    buf[0] = '\x05';            /* VER = 5 */
+    buf[1] = '\x01';            /* CMD = 1 (CONNECT) */
+    buf[2] = '\x00';            /* RSV */
+    buf[3] = '\x03';            /* ATYP = 3 (DOMAINNAME) */
+
+    len = strlen(host);
+    len = (5 + len + 2 > sizeof(buf)) ? (sizeof(buf) - 5 - 2) : len;
+
+    buf[4] = (char) len;
+    memcpy(buf + 5, host, len);
+
+    int port = port_from_servname(servname);
+    if (port ==0)
+    {
+        msg(D_LINK_ERRORS, "establish_socks_proxy_passthrough: Cannot convert %s to port number", servname);
+        goto error;
+    }
+
+    buf[5 + len] = (char) (port >> 8);
+    buf[5 + len + 1] = (char) (port & 0xff);
+
+    {
+        const ssize_t size = send(sd, buf, 5 + len + 2, MSG_NOSIGNAL);
+        if ((int)size != 5 + (int)len + 2)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "establish_socks_proxy_passthru: TCP port write failed on send()");
+            goto error;
+        }
+    }
+
+
+    /* receive reply from Socks proxy and discard */
+    if (!recv_socks_reply(sd, NULL, signal_received))
+    {
+        goto error;
+    }
+
+    return;
+
+error:
+    if (!*signal_received)
+    {
+        *signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- socks error */
+    }
+    return;
+}
+
+void
+establish_socks_proxy_udpassoc(struct socks_proxy_info *p,
+                               socket_descriptor_t ctrl_sd,  /* already open to proxy */
+                               socket_descriptor_t udp_sd,
+                               struct openvpn_sockaddr *relay_addr,
+                               volatile int *signal_received)
+{
+    if (!socks_handshake(p, ctrl_sd, signal_received))
+    {
+        goto error;
+    }
+
+    {
+        /* send Socks UDP ASSOCIATE message */
+        /* VER = 5, CMD = 3 (UDP ASSOCIATE), RSV = 0, ATYP = 1 (IP V4),
+         * BND.ADDR = 0, BND.PORT = 0 */
+        const ssize_t size = send(ctrl_sd,
+                                  "\x05\x03\x00\x01\x00\x00\x00\x00\x00\x00",
+                                  10, MSG_NOSIGNAL);
+        if (size != 10)
+        {
+            msg(D_LINK_ERRORS | M_ERRNO, "establish_socks_proxy_passthru: TCP port write failed on send()");
+            goto error;
+        }
+    }
+
+    /* receive reply from Socks proxy */
+    CLEAR(*relay_addr);
+    if (!recv_socks_reply(ctrl_sd, relay_addr, signal_received))
+    {
+        goto error;
+    }
+
+    return;
+
+error:
+    if (!*signal_received)
+    {
+        *signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- socks error */
+    }
+    return;
+}
+
+/*
+ * Remove the 10 byte socks5 header from an incoming
+ * UDP packet, setting *from to the source address.
+ *
+ * Run after UDP read.
+ */
+void
+socks_process_incoming_udp(struct buffer *buf,
+                           struct link_socket_actual *from)
+{
+    int atyp;
+
+    if (BLEN(buf) < 10)
+    {
+        goto error;
+    }
+
+    buf_read_u16(buf);
+    if (buf_read_u8(buf) != 0)
+    {
+        goto error;
+    }
+
+    atyp = buf_read_u8(buf);
+    if (atyp != 1)              /* ATYP == 1 (IP V4) */
+    {
+        goto error;
+    }
+
+    buf_read(buf, &from->dest.addr.in4.sin_addr, sizeof(from->dest.addr.in4.sin_addr));
+    buf_read(buf, &from->dest.addr.in4.sin_port, sizeof(from->dest.addr.in4.sin_port));
+
+    return;
+
+error:
+    buf->len = 0;
+}
+
+/*
+ * Add a 10 byte socks header prior to UDP write.
+ * *to is the destination address.
+ *
+ * Run before UDP write.
+ * Returns the size of the header.
+ */
+int
+socks_process_outgoing_udp(struct buffer *buf,
+                           const struct link_socket_actual *to)
+{
+    /*
+     * Get a 10 byte subset buffer prepended to buf --
+     * we expect these bytes will be here because
+     * we allocated frame space in socks_adjust_frame_parameters.
+     */
+    struct buffer head = buf_sub(buf, 10, true);
+
+    /* crash if not enough headroom in buf */
+    ASSERT(buf_defined(&head));
+
+    buf_write_u16(&head, 0);    /* RSV = 0 */
+    buf_write_u8(&head, 0);     /* FRAG = 0 */
+    buf_write_u8(&head, '\x01'); /* ATYP = 1 (IP V4) */
+    buf_write(&head, &to->dest.addr.in4.sin_addr, sizeof(to->dest.addr.in4.sin_addr));
+    buf_write(&head, &to->dest.addr.in4.sin_port, sizeof(to->dest.addr.in4.sin_port));
+
+    return 10;
+}
diff --git a/src/openvpn/socks.h b/src/openvpn/socks.h
new file mode 100644
index 0000000..aef873c
--- /dev/null
+++ b/src/openvpn/socks.h
@@ -0,0 +1,71 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * 2004-01-30: Added Socks5 proxy support
+ *   (Christof Meerwald, http://cmeerw.org)
+ */
+
+#ifndef SOCKS_H
+#define SOCKS_H
+
+#include "buffer.h"
+
+struct openvpn_sockaddr;
+struct link_socket_actual;
+
+struct socks_proxy_info {
+    bool defined;
+
+    char server[128];
+    const char *port;
+    char authfile[256];
+};
+
+void socks_adjust_frame_parameters(struct frame *frame, int proto);
+
+struct socks_proxy_info *socks_proxy_new(const char *server,
+                                         const char *port,
+                                         const char *authfile);
+
+void socks_proxy_close(struct socks_proxy_info *sp);
+
+void establish_socks_proxy_passthru(struct socks_proxy_info *p,
+                                    socket_descriptor_t sd,  /* already open to proxy */
+                                    const char *host,        /* openvpn server remote */
+                                    const char *servname,          /* openvpn server port */
+                                    volatile int *signal_received);
+
+void establish_socks_proxy_udpassoc(struct socks_proxy_info *p,
+                                    socket_descriptor_t ctrl_sd,  /* already open to proxy */
+                                    socket_descriptor_t udp_sd,
+                                    struct openvpn_sockaddr *relay_addr,
+                                    volatile int *signal_received);
+
+void socks_process_incoming_udp(struct buffer *buf,
+                                struct link_socket_actual *from);
+
+int socks_process_outgoing_udp(struct buffer *buf,
+                               const struct link_socket_actual *to);
+
+#endif /* ifndef SOCKS_H */
diff --git a/src/openvpn/ssl.c b/src/openvpn/ssl.c
new file mode 100644
index 0000000..cf66899
--- /dev/null
+++ b/src/openvpn/ssl.c
@@ -0,0 +1,4323 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *  Copyright (C) 2008-2013 David Sommerseth <dazo@users.sourceforge.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel SSL/Data channel negotiation Module
+ */
+
+/*
+ * The routines in this file deal with dynamically negotiating
+ * the data channel HMAC and cipher keys through a TLS session.
+ *
+ * Both the TLS session and the data channel are multiplexed
+ * over the same TCP/UDP port.
+ */
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+#include "win32.h"
+
+#if defined(ENABLE_CRYPTO)
+
+#include "error.h"
+#include "common.h"
+#include "socket.h"
+#include "misc.h"
+#include "fdmisc.h"
+#include "interval.h"
+#include "perf.h"
+#include "status.h"
+#include "gremlin.h"
+#include "pkcs11.h"
+#include "route.h"
+#include "tls_crypt.h"
+
+#include "ssl.h"
+#include "ssl_verify.h"
+#include "ssl_backend.h"
+
+#include "memdbg.h"
+
+#ifndef ENABLE_OCC
+static const char ssl_default_options_string[] = "V0 UNDEF";
+#endif
+
+static inline const char *
+local_options_string(const struct tls_session *session)
+{
+#ifdef ENABLE_OCC
+    return session->opt->local_options;
+#else
+    return ssl_default_options_string;
+#endif
+}
+
+#ifdef MEASURE_TLS_HANDSHAKE_STATS
+
+static int tls_handshake_success; /* GLOBAL */
+static int tls_handshake_error;   /* GLOBAL */
+static int tls_packets_generated; /* GLOBAL */
+static int tls_packets_sent;      /* GLOBAL */
+
+#define INCR_SENT       ++tls_packets_sent
+#define INCR_GENERATED  ++tls_packets_generated
+#define INCR_SUCCESS    ++tls_handshake_success
+#define INCR_ERROR      ++tls_handshake_error
+
+void
+show_tls_performance_stats(void)
+{
+    msg(D_TLS_DEBUG_LOW, "TLS Handshakes, success=%f%% (good=%d, bad=%d), retransmits=%f%%",
+        (double) tls_handshake_success / (tls_handshake_success + tls_handshake_error) * 100.0,
+        tls_handshake_success, tls_handshake_error,
+        (double) (tls_packets_sent - tls_packets_generated) / tls_packets_generated * 100.0);
+}
+#else  /* ifdef MEASURE_TLS_HANDSHAKE_STATS */
+
+#define INCR_SENT
+#define INCR_GENERATED
+#define INCR_SUCCESS
+#define INCR_ERROR
+
+#endif /* ifdef MEASURE_TLS_HANDSHAKE_STATS */
+
+/**
+ * SSL/TLS Cipher suite name translation table
+ */
+static const tls_cipher_name_pair tls_cipher_name_translation_table[] = {
+    {"ADH-SEED-SHA", "TLS-DH-anon-WITH-SEED-CBC-SHA"},
+    {"AES128-GCM-SHA256", "TLS-RSA-WITH-AES-128-GCM-SHA256"},
+    {"AES128-SHA256", "TLS-RSA-WITH-AES-128-CBC-SHA256"},
+    {"AES128-SHA", "TLS-RSA-WITH-AES-128-CBC-SHA"},
+    {"AES256-GCM-SHA384", "TLS-RSA-WITH-AES-256-GCM-SHA384"},
+    {"AES256-SHA256", "TLS-RSA-WITH-AES-256-CBC-SHA256"},
+    {"AES256-SHA", "TLS-RSA-WITH-AES-256-CBC-SHA"},
+    {"CAMELLIA128-SHA256", "TLS-RSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"CAMELLIA128-SHA", "TLS-RSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"CAMELLIA256-SHA256", "TLS-RSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"CAMELLIA256-SHA", "TLS-RSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"DES-CBC3-SHA", "TLS-RSA-WITH-3DES-EDE-CBC-SHA"},
+    {"DES-CBC-SHA", "TLS-RSA-WITH-DES-CBC-SHA"},
+    {"DH-DSS-SEED-SHA", "TLS-DH-DSS-WITH-SEED-CBC-SHA"},
+    {"DHE-DSS-AES128-GCM-SHA256", "TLS-DHE-DSS-WITH-AES-128-GCM-SHA256"},
+    {"DHE-DSS-AES128-SHA256", "TLS-DHE-DSS-WITH-AES-128-CBC-SHA256"},
+    {"DHE-DSS-AES128-SHA", "TLS-DHE-DSS-WITH-AES-128-CBC-SHA"},
+    {"DHE-DSS-AES256-GCM-SHA384", "TLS-DHE-DSS-WITH-AES-256-GCM-SHA384"},
+    {"DHE-DSS-AES256-SHA256", "TLS-DHE-DSS-WITH-AES-256-CBC-SHA256"},
+    {"DHE-DSS-AES256-SHA", "TLS-DHE-DSS-WITH-AES-256-CBC-SHA"},
+    {"DHE-DSS-CAMELLIA128-SHA256", "TLS-DHE-DSS-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"DHE-DSS-CAMELLIA128-SHA", "TLS-DHE-DSS-WITH-CAMELLIA-128-CBC-SHA"},
+    {"DHE-DSS-CAMELLIA256-SHA256", "TLS-DHE-DSS-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"DHE-DSS-CAMELLIA256-SHA", "TLS-DHE-DSS-WITH-CAMELLIA-256-CBC-SHA"},
+    {"DHE-DSS-SEED-SHA", "TLS-DHE-DSS-WITH-SEED-CBC-SHA"},
+    {"DHE-RSA-AES128-GCM-SHA256", "TLS-DHE-RSA-WITH-AES-128-GCM-SHA256"},
+    {"DHE-RSA-AES128-SHA256", "TLS-DHE-RSA-WITH-AES-128-CBC-SHA256"},
+    {"DHE-RSA-AES128-SHA", "TLS-DHE-RSA-WITH-AES-128-CBC-SHA"},
+    {"DHE-RSA-AES256-GCM-SHA384", "TLS-DHE-RSA-WITH-AES-256-GCM-SHA384"},
+    {"DHE-RSA-AES256-SHA256", "TLS-DHE-RSA-WITH-AES-256-CBC-SHA256"},
+    {"DHE-RSA-AES256-SHA", "TLS-DHE-RSA-WITH-AES-256-CBC-SHA"},
+    {"DHE-RSA-CAMELLIA128-SHA256", "TLS-DHE-RSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"DHE-RSA-CAMELLIA128-SHA", "TLS-DHE-RSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"DHE-RSA-CAMELLIA256-SHA256", "TLS-DHE-RSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"DHE-RSA-CAMELLIA256-SHA", "TLS-DHE-RSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"DHE-RSA-CHACHA20-POLY1305", "TLS-DHE-RSA-WITH-CHACHA20-POLY1305-SHA256"},
+    {"DHE-RSA-SEED-SHA", "TLS-DHE-RSA-WITH-SEED-CBC-SHA"},
+    {"DH-RSA-SEED-SHA", "TLS-DH-RSA-WITH-SEED-CBC-SHA"},
+    {"ECDH-ECDSA-AES128-GCM-SHA256", "TLS-ECDH-ECDSA-WITH-AES-128-GCM-SHA256"},
+    {"ECDH-ECDSA-AES128-SHA256", "TLS-ECDH-ECDSA-WITH-AES-128-CBC-SHA256"},
+    {"ECDH-ECDSA-AES128-SHA", "TLS-ECDH-ECDSA-WITH-AES-128-CBC-SHA"},
+    {"ECDH-ECDSA-AES256-GCM-SHA384", "TLS-ECDH-ECDSA-WITH-AES-256-GCM-SHA384"},
+    {"ECDH-ECDSA-AES256-SHA256", "TLS-ECDH-ECDSA-WITH-AES-256-CBC-SHA256"},
+    {"ECDH-ECDSA-AES256-SHA384", "TLS-ECDH-ECDSA-WITH-AES-256-CBC-SHA384"},
+    {"ECDH-ECDSA-AES256-SHA", "TLS-ECDH-ECDSA-WITH-AES-256-CBC-SHA"},
+    {"ECDH-ECDSA-CAMELLIA128-SHA256", "TLS-ECDH-ECDSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"ECDH-ECDSA-CAMELLIA128-SHA", "TLS-ECDH-ECDSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"ECDH-ECDSA-CAMELLIA256-SHA256", "TLS-ECDH-ECDSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"ECDH-ECDSA-CAMELLIA256-SHA", "TLS-ECDH-ECDSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"ECDH-ECDSA-DES-CBC3-SHA", "TLS-ECDH-ECDSA-WITH-3DES-EDE-CBC-SHA"},
+    {"ECDH-ECDSA-DES-CBC-SHA", "TLS-ECDH-ECDSA-WITH-DES-CBC-SHA"},
+    {"ECDH-ECDSA-RC4-SHA", "TLS-ECDH-ECDSA-WITH-RC4-128-SHA"},
+    {"ECDHE-ECDSA-AES128-GCM-SHA256", "TLS-ECDHE-ECDSA-WITH-AES-128-GCM-SHA256"},
+    {"ECDHE-ECDSA-AES128-SHA256", "TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA256"},
+    {"ECDHE-ECDSA-AES128-SHA384", "TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA384"},
+    {"ECDHE-ECDSA-AES128-SHA", "TLS-ECDHE-ECDSA-WITH-AES-128-CBC-SHA"},
+    {"ECDHE-ECDSA-AES256-GCM-SHA384", "TLS-ECDHE-ECDSA-WITH-AES-256-GCM-SHA384"},
+    {"ECDHE-ECDSA-AES256-SHA256", "TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA256"},
+    {"ECDHE-ECDSA-AES256-SHA384", "TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA384"},
+    {"ECDHE-ECDSA-AES256-SHA", "TLS-ECDHE-ECDSA-WITH-AES-256-CBC-SHA"},
+    {"ECDHE-ECDSA-CAMELLIA128-SHA256", "TLS-ECDHE-ECDSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"ECDHE-ECDSA-CAMELLIA128-SHA", "TLS-ECDHE-ECDSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"ECDHE-ECDSA-CAMELLIA256-SHA256", "TLS-ECDHE-ECDSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"ECDHE-ECDSA-CAMELLIA256-SHA", "TLS-ECDHE-ECDSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"ECDHE-ECDSA-CHACHA20-POLY1305", "TLS-ECDHE-ECDSA-WITH-CHACHA20-POLY1305-SHA256"},
+    {"ECDHE-ECDSA-DES-CBC3-SHA", "TLS-ECDHE-ECDSA-WITH-3DES-EDE-CBC-SHA"},
+    {"ECDHE-ECDSA-DES-CBC-SHA", "TLS-ECDHE-ECDSA-WITH-DES-CBC-SHA"},
+    {"ECDHE-ECDSA-RC4-SHA", "TLS-ECDHE-ECDSA-WITH-RC4-128-SHA"},
+    {"ECDHE-RSA-AES128-GCM-SHA256", "TLS-ECDHE-RSA-WITH-AES-128-GCM-SHA256"},
+    {"ECDHE-RSA-AES128-SHA256", "TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA256"},
+    {"ECDHE-RSA-AES128-SHA384", "TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA384"},
+    {"ECDHE-RSA-AES128-SHA", "TLS-ECDHE-RSA-WITH-AES-128-CBC-SHA"},
+    {"ECDHE-RSA-AES256-GCM-SHA384", "TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384"},
+    {"ECDHE-RSA-AES256-SHA256", "TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA256"},
+    {"ECDHE-RSA-AES256-SHA384", "TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA384"},
+    {"ECDHE-RSA-AES256-SHA", "TLS-ECDHE-RSA-WITH-AES-256-CBC-SHA"},
+    {"ECDHE-RSA-CAMELLIA128-SHA256", "TLS-ECDHE-RSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"ECDHE-RSA-CAMELLIA128-SHA", "TLS-ECDHE-RSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"ECDHE-RSA-CAMELLIA256-SHA256", "TLS-ECDHE-RSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"ECDHE-RSA-CAMELLIA256-SHA", "TLS-ECDHE-RSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"ECDHE-RSA-CHACHA20-POLY1305", "TLS-ECDHE-RSA-WITH-CHACHA20-POLY1305-SHA256"},
+    {"ECDHE-RSA-DES-CBC3-SHA", "TLS-ECDHE-RSA-WITH-3DES-EDE-CBC-SHA"},
+    {"ECDHE-RSA-DES-CBC-SHA", "TLS-ECDHE-RSA-WITH-DES-CBC-SHA"},
+    {"ECDHE-RSA-RC4-SHA", "TLS-ECDHE-RSA-WITH-RC4-128-SHA"},
+    {"ECDH-RSA-AES128-GCM-SHA256", "TLS-ECDH-RSA-WITH-AES-128-GCM-SHA256"},
+    {"ECDH-RSA-AES128-SHA256", "TLS-ECDH-RSA-WITH-AES-128-CBC-SHA256"},
+    {"ECDH-RSA-AES128-SHA384", "TLS-ECDH-RSA-WITH-AES-128-CBC-SHA384"},
+    {"ECDH-RSA-AES128-SHA", "TLS-ECDH-RSA-WITH-AES-128-CBC-SHA"},
+    {"ECDH-RSA-AES256-GCM-SHA384", "TLS-ECDH-RSA-WITH-AES-256-GCM-SHA384"},
+    {"ECDH-RSA-AES256-SHA256", "TLS-ECDH-RSA-WITH-AES-256-CBC-SHA256"},
+    {"ECDH-RSA-AES256-SHA384", "TLS-ECDH-RSA-WITH-AES-256-CBC-SHA384"},
+    {"ECDH-RSA-AES256-SHA", "TLS-ECDH-RSA-WITH-AES-256-CBC-SHA"},
+    {"ECDH-RSA-CAMELLIA128-SHA256", "TLS-ECDH-RSA-WITH-CAMELLIA-128-CBC-SHA256"},
+    {"ECDH-RSA-CAMELLIA128-SHA", "TLS-ECDH-RSA-WITH-CAMELLIA-128-CBC-SHA"},
+    {"ECDH-RSA-CAMELLIA256-SHA256", "TLS-ECDH-RSA-WITH-CAMELLIA-256-CBC-SHA256"},
+    {"ECDH-RSA-CAMELLIA256-SHA", "TLS-ECDH-RSA-WITH-CAMELLIA-256-CBC-SHA"},
+    {"ECDH-RSA-DES-CBC3-SHA", "TLS-ECDH-RSA-WITH-3DES-EDE-CBC-SHA"},
+    {"ECDH-RSA-DES-CBC-SHA", "TLS-ECDH-RSA-WITH-DES-CBC-SHA"},
+    {"ECDH-RSA-RC4-SHA", "TLS-ECDH-RSA-WITH-RC4-128-SHA"},
+    {"EDH-DSS-DES-CBC3-SHA", "TLS-DHE-DSS-WITH-3DES-EDE-CBC-SHA"},
+    {"EDH-DSS-DES-CBC-SHA", "TLS-DHE-DSS-WITH-DES-CBC-SHA"},
+    {"EDH-RSA-DES-CBC3-SHA", "TLS-DHE-RSA-WITH-3DES-EDE-CBC-SHA"},
+    {"EDH-RSA-DES-CBC-SHA", "TLS-DHE-RSA-WITH-DES-CBC-SHA"},
+    {"EXP-DES-CBC-SHA", "TLS-RSA-EXPORT-WITH-DES40-CBC-SHA"},
+    {"EXP-EDH-DSS-DES-CBC-SHA", "TLS-DH-DSS-EXPORT-WITH-DES40-CBC-SHA"},
+    {"EXP-EDH-RSA-DES-CBC-SHA", "TLS-DH-RSA-EXPORT-WITH-DES40-CBC-SHA"},
+    {"EXP-RC2-CBC-MD5", "TLS-RSA-EXPORT-WITH-RC2-CBC-40-MD5"},
+    {"EXP-RC4-MD5", "TLS-RSA-EXPORT-WITH-RC4-40-MD5"},
+    {"NULL-MD5", "TLS-RSA-WITH-NULL-MD5"},
+    {"NULL-SHA256", "TLS-RSA-WITH-NULL-SHA256"},
+    {"NULL-SHA", "TLS-RSA-WITH-NULL-SHA"},
+    {"PSK-3DES-EDE-CBC-SHA", "TLS-PSK-WITH-3DES-EDE-CBC-SHA"},
+    {"PSK-AES128-CBC-SHA", "TLS-PSK-WITH-AES-128-CBC-SHA"},
+    {"PSK-AES256-CBC-SHA", "TLS-PSK-WITH-AES-256-CBC-SHA"},
+    {"PSK-RC4-SHA", "TLS-PSK-WITH-RC4-128-SHA"},
+    {"RC4-MD5", "TLS-RSA-WITH-RC4-128-MD5"},
+    {"RC4-SHA", "TLS-RSA-WITH-RC4-128-SHA"},
+    {"SEED-SHA", "TLS-RSA-WITH-SEED-CBC-SHA"},
+    {"SRP-DSS-3DES-EDE-CBC-SHA", "TLS-SRP-SHA-DSS-WITH-3DES-EDE-CBC-SHA"},
+    {"SRP-DSS-AES-128-CBC-SHA", "TLS-SRP-SHA-DSS-WITH-AES-128-CBC-SHA"},
+    {"SRP-DSS-AES-256-CBC-SHA", "TLS-SRP-SHA-DSS-WITH-AES-256-CBC-SHA"},
+    {"SRP-RSA-3DES-EDE-CBC-SHA", "TLS-SRP-SHA-RSA-WITH-3DES-EDE-CBC-SHA"},
+    {"SRP-RSA-AES-128-CBC-SHA", "TLS-SRP-SHA-RSA-WITH-AES-128-CBC-SHA"},
+    {"SRP-RSA-AES-256-CBC-SHA", "TLS-SRP-SHA-RSA-WITH-AES-256-CBC-SHA"},
+#ifdef ENABLE_CRYPTO_OPENSSL
+    /* OpenSSL-specific group names */
+    {"DEFAULT", "DEFAULT"},
+    {"ALL", "ALL"},
+    {"HIGH", "HIGH"}, {"!HIGH", "!HIGH"},
+    {"MEDIUM", "MEDIUM"}, {"!MEDIUM", "!MEDIUM"},
+    {"LOW", "LOW"}, {"!LOW", "!LOW"},
+    {"ECDH", "ECDH"}, {"!ECDH", "!ECDH"},
+    {"ECDSA", "ECDSA"}, {"!ECDSA", "!ECDSA"},
+    {"EDH", "EDH"}, {"!EDH", "!EDH"},
+    {"EXP", "EXP"}, {"!EXP", "!EXP"},
+    {"RSA", "RSA"}, {"!RSA", "!RSA"},
+    {"kRSA", "kRSA"}, {"!kRSA", "!kRSA"},
+    {"SRP", "SRP"}, {"!SRP", "!SRP"},
+#endif
+    {NULL, NULL}
+};
+
+/**
+ * Update the implicit IV for a key_ctx_bi based on TLS session ids and cipher
+ * used.
+ *
+ * Note that the implicit IV is based on the HMAC key, but only in AEAD modes
+ * where the HMAC key is not used for an actual HMAC.
+ *
+ * @param ctx                   Encrypt/decrypt key context
+ * @param key                   HMAC key, used to calculate implicit IV
+ * @param key_len               HMAC key length
+ */
+static void
+key_ctx_update_implicit_iv(struct key_ctx *ctx, uint8_t *key, size_t key_len);
+
+const tls_cipher_name_pair *
+tls_get_cipher_name_pair(const char *cipher_name, size_t len)
+{
+    const tls_cipher_name_pair *pair = tls_cipher_name_translation_table;
+
+    while (pair->openssl_name != NULL)
+    {
+        if ((strlen(pair->openssl_name) == len && 0 == memcmp(cipher_name, pair->openssl_name, len))
+            || (strlen(pair->iana_name) == len && 0 == memcmp(cipher_name, pair->iana_name, len)))
+        {
+            return pair;
+        }
+        pair++;
+    }
+
+    /* No entry found, return NULL */
+    return NULL;
+}
+
+/**
+ * Limit the reneg_bytes value when using a small-block (<128 bytes) cipher.
+ *
+ * @param cipher        The current cipher (may be NULL).
+ * @param reneg_bytes   Pointer to the current reneg_bytes, updated if needed.
+ *                      May *not* be NULL.
+ */
+static void
+tls_limit_reneg_bytes(const cipher_kt_t *cipher, int *reneg_bytes)
+{
+    if (cipher && (cipher_kt_block_size(cipher) < 128/8))
+    {
+        if (*reneg_bytes == -1) /* Not user-specified */
+        {
+            msg(M_WARN, "WARNING: cipher with small block size in use, "
+                "reducing reneg-bytes to 64MB to mitigate SWEET32 attacks.");
+            *reneg_bytes = 64 * 1024 * 1024;
+        }
+    }
+}
+
+/*
+ * Max number of bytes we will add
+ * for data structures common to both
+ * data and control channel packets.
+ * (opcode only).
+ */
+void
+tls_adjust_frame_parameters(struct frame *frame)
+{
+    frame_add_to_extra_frame(frame, 1); /* space for opcode */
+}
+
+/*
+ * Max number of bytes we will add
+ * to control channel packet.
+ */
+static void
+tls_init_control_channel_frame_parameters(const struct frame *data_channel_frame,
+                                          struct frame *frame)
+{
+    /*
+     * frame->extra_frame is already initialized with tls_auth buffer requirements,
+     * if --tls-auth is enabled.
+     */
+
+    /* inherit link MTU and extra_link from data channel */
+    frame->link_mtu = data_channel_frame->link_mtu;
+    frame->extra_link = data_channel_frame->extra_link;
+
+    /* set extra_frame */
+    tls_adjust_frame_parameters(frame);
+    reliable_ack_adjust_frame_parameters(frame, CONTROL_SEND_ACK_MAX);
+    frame_add_to_extra_frame(frame, SID_SIZE + sizeof(packet_id_type));
+
+    /* set dynamic link MTU to cap control channel packets at 1250 bytes */
+    ASSERT(TUN_LINK_DELTA(frame) < min_int(frame->link_mtu, 1250));
+    frame->link_mtu_dynamic = min_int(frame->link_mtu, 1250) - TUN_LINK_DELTA(frame);
+}
+
+void
+init_ssl_lib(void)
+{
+    tls_init_lib();
+
+    crypto_init_lib();
+}
+
+void
+free_ssl_lib(void)
+{
+    crypto_uninit_lib();
+    prng_uninit();
+
+    tls_free_lib();
+}
+
+/*
+ * OpenSSL library calls pem_password_callback if the
+ * private key is protected by a password.
+ */
+
+static struct user_pass passbuf; /* GLOBAL */
+
+void
+pem_password_setup(const char *auth_file)
+{
+    if (!strlen(passbuf.password))
+    {
+        get_user_pass(&passbuf, auth_file, UP_TYPE_PRIVATE_KEY, GET_USER_PASS_MANAGEMENT|GET_USER_PASS_PASSWORD_ONLY);
+    }
+}
+
+int
+pem_password_callback(char *buf, int size, int rwflag, void *u)
+{
+    if (buf)
+    {
+        /* prompt for password even if --askpass wasn't specified */
+        pem_password_setup(NULL);
+        strncpynt(buf, passbuf.password, size);
+        purge_user_pass(&passbuf, false);
+
+        return strlen(buf);
+    }
+    return 0;
+}
+
+/*
+ * Auth username/password handling
+ */
+
+static bool auth_user_pass_enabled;     /* GLOBAL */
+static struct user_pass auth_user_pass; /* GLOBAL */
+static struct user_pass auth_token;     /* GLOBAL */
+
+#ifdef ENABLE_CLIENT_CR
+static char *auth_challenge; /* GLOBAL */
+#endif
+
+void
+auth_user_pass_setup(const char *auth_file, const struct static_challenge_info *sci)
+{
+    auth_user_pass_enabled = true;
+    if (!auth_user_pass.defined && !auth_token.defined)
+    {
+#if AUTO_USERID
+        get_user_pass_auto_userid(&auth_user_pass, auth_file);
+#else
+#ifdef ENABLE_CLIENT_CR
+        if (auth_challenge) /* dynamic challenge/response */
+        {
+            get_user_pass_cr(&auth_user_pass,
+                             auth_file,
+                             UP_TYPE_AUTH,
+                             GET_USER_PASS_MANAGEMENT|GET_USER_PASS_DYNAMIC_CHALLENGE,
+                             auth_challenge);
+        }
+        else if (sci) /* static challenge response */
+        {
+            int flags = GET_USER_PASS_MANAGEMENT|GET_USER_PASS_STATIC_CHALLENGE;
+            if (sci->flags & SC_ECHO)
+            {
+                flags |= GET_USER_PASS_STATIC_CHALLENGE_ECHO;
+            }
+            get_user_pass_cr(&auth_user_pass,
+                             auth_file,
+                             UP_TYPE_AUTH,
+                             flags,
+                             sci->challenge_text);
+        }
+        else
+#endif /* ifdef ENABLE_CLIENT_CR */
+        get_user_pass(&auth_user_pass, auth_file, UP_TYPE_AUTH, GET_USER_PASS_MANAGEMENT);
+#endif /* if AUTO_USERID */
+    }
+}
+
+/*
+ * Disable password caching
+ */
+void
+ssl_set_auth_nocache(void)
+{
+    passbuf.nocache = true;
+    auth_user_pass.nocache = true;
+    /* wait for push-reply, because auth-token may still need the username */
+    auth_user_pass.wait_for_push = true;
+}
+
+/*
+ * Set an authentication token
+ */
+void
+ssl_set_auth_token(const char *token)
+{
+    set_auth_token(&auth_user_pass, &auth_token, token);
+}
+
+/*
+ * Cleans an auth token and checks if it was active
+ */
+bool
+ssl_clean_auth_token (void)
+{
+    bool wasdefined = auth_token.defined;
+    purge_user_pass(&auth_token, true);
+    return wasdefined;
+}
+
+/*
+ * Forget private key password AND auth-user-pass username/password.
+ */
+void
+ssl_purge_auth(const bool auth_user_pass_only)
+{
+    if (!auth_user_pass_only)
+    {
+#ifdef ENABLE_PKCS11
+        pkcs11_logout();
+#endif
+        purge_user_pass(&passbuf, true);
+    }
+    purge_user_pass(&auth_user_pass, true);
+#ifdef ENABLE_CLIENT_CR
+    ssl_purge_auth_challenge();
+#endif
+}
+
+#ifdef ENABLE_CLIENT_CR
+
+void
+ssl_purge_auth_challenge(void)
+{
+    free(auth_challenge);
+    auth_challenge = NULL;
+}
+
+void
+ssl_put_auth_challenge(const char *cr_str)
+{
+    ssl_purge_auth_challenge();
+    auth_challenge = string_alloc(cr_str, NULL);
+}
+
+#endif
+
+/*
+ * Parse a TLS version string, returning a TLS_VER_x constant.
+ * If version string is not recognized and extra == "or-highest",
+ * return tls_version_max().
+ */
+int
+tls_version_parse(const char *vstr, const char *extra)
+{
+    const int max_version = tls_version_max();
+    if (!strcmp(vstr, "1.0") && TLS_VER_1_0 <= max_version)
+    {
+        return TLS_VER_1_0;
+    }
+    else if (!strcmp(vstr, "1.1") && TLS_VER_1_1 <= max_version)
+    {
+        return TLS_VER_1_1;
+    }
+    else if (!strcmp(vstr, "1.2") && TLS_VER_1_2 <= max_version)
+    {
+        return TLS_VER_1_2;
+    }
+    else if (!strcmp(vstr, "1.3") && TLS_VER_1_3 <= max_version)
+    {
+        return TLS_VER_1_3;
+    }
+    else if (extra && !strcmp(extra, "or-highest"))
+    {
+        return max_version;
+    }
+    else
+    {
+        return TLS_VER_BAD;
+    }
+}
+
+/**
+ * Load (or possibly reload) the CRL file into the SSL context.
+ * No reload is performed under the following conditions:
+ * - the CRL file was passed inline
+ * - the CRL file was not modified since the last (re)load
+ *
+ * @param ssl_ctx       The TLS context to use when reloading the CRL
+ * @param crl_file      The file name to load the CRL from, or
+ *                      "[[INLINE]]" in the case of inline files.
+ * @param crl_inline    A string containing the CRL
+ */
+static void
+tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx, const char *crl_file,
+                   const char *crl_file_inline)
+{
+    /* if something goes wrong with stat(), we'll store 0 as mtime */
+    platform_stat_t crl_stat = {0};
+
+    /*
+     * an inline CRL can't change at runtime, therefore there is no need to
+     * reload it. It will be reloaded upon config change + SIGHUP.
+     * Use always '1' as dummy timestamp in this case: it will trigger the
+     * first load, but will prevent any future reload.
+     */
+    if (crl_file_inline)
+    {
+        crl_stat.st_mtime = 1;
+    }
+    else if (platform_stat(crl_file, &crl_stat) < 0)
+    {
+        msg(M_WARN, "WARNING: Failed to stat CRL file, not (re)loading CRL.");
+        return;
+    }
+
+    /*
+     * Store the CRL if this is the first time or if the file was changed since
+     * the last load.
+     * Note: Windows does not support tv_nsec.
+     */
+    if ((ssl_ctx->crl_last_size == crl_stat.st_size)
+        && (ssl_ctx->crl_last_mtime == crl_stat.st_mtime))
+    {
+        return;
+    }
+
+    ssl_ctx->crl_last_mtime = crl_stat.st_mtime;
+    ssl_ctx->crl_last_size = crl_stat.st_size;
+    backend_tls_ctx_reload_crl(ssl_ctx, crl_file, crl_file_inline);
+}
+
+/*
+ * Initialize SSL context.
+ * All files are in PEM format.
+ */
+void
+init_ssl(const struct options *options, struct tls_root_ctx *new_ctx)
+{
+    ASSERT(NULL != new_ctx);
+
+    tls_clear_error();
+
+    if (options->tls_server)
+    {
+        tls_ctx_server_new(new_ctx);
+
+        if (options->dh_file)
+        {
+            tls_ctx_load_dh_params(new_ctx, options->dh_file,
+                                   options->dh_file_inline);
+        }
+    }
+    else                        /* if client */
+    {
+        tls_ctx_client_new(new_ctx);
+    }
+
+    /* Restrict allowed certificate crypto algorithms */
+    tls_ctx_set_cert_profile(new_ctx, options->tls_cert_profile);
+
+    /* Allowable ciphers */
+    /* Since @SECLEVEL also influences loading of certificates, set the
+     * cipher restrictions before loading certificates */
+    tls_ctx_restrict_ciphers(new_ctx, options->cipher_list);
+    tls_ctx_restrict_ciphers_tls13(new_ctx, options->cipher_list_tls13);
+
+    if (!tls_ctx_set_options(new_ctx, options->ssl_flags))
+    {
+        goto err;
+    }
+
+    if (options->pkcs12_file)
+    {
+        if (0 != tls_ctx_load_pkcs12(new_ctx, options->pkcs12_file,
+                                     options->pkcs12_file_inline, !options->ca_file))
+        {
+            goto err;
+        }
+    }
+#ifdef ENABLE_PKCS11
+    else if (options->pkcs11_providers[0])
+    {
+        if (!tls_ctx_use_pkcs11(new_ctx, options->pkcs11_id_management, options->pkcs11_id))
+        {
+            msg(M_WARN, "Cannot load certificate \"%s\" using PKCS#11 interface",
+                options->pkcs11_id);
+            goto err;
+        }
+    }
+#endif
+#ifdef ENABLE_CRYPTOAPI
+    else if (options->cryptoapi_cert)
+    {
+        tls_ctx_load_cryptoapi(new_ctx, options->cryptoapi_cert);
+    }
+#endif
+#ifdef MANAGMENT_EXTERNAL_KEY
+    else if ((options->management_flags & MF_EXTERNAL_KEY)
+             && (options->cert_file || options->management_flags & MF_EXTERNAL_CERT))
+    {
+        if (options->cert_file)
+        {
+            tls_ctx_use_external_private_key(new_ctx, options->cert_file,
+                                             options->cert_file_inline);
+        }
+        else
+        {
+            char *external_certificate = management_query_cert(management,
+                                                               options->management_certificate);
+            tls_ctx_use_external_private_key(new_ctx, INLINE_FILE_TAG,
+                                             external_certificate);
+            free(external_certificate);
+        }
+    }
+#endif
+    else
+    {
+        /* Load Certificate */
+        if (options->cert_file)
+        {
+            tls_ctx_load_cert_file(new_ctx, options->cert_file, options->cert_file_inline);
+        }
+
+        /* Load Private Key */
+        if (options->priv_key_file)
+        {
+            if (0 != tls_ctx_load_priv_file(new_ctx, options->priv_key_file, options->priv_key_file_inline))
+            {
+                goto err;
+            }
+        }
+    }
+
+    if (options->ca_file || options->ca_path)
+    {
+        tls_ctx_load_ca(new_ctx, options->ca_file, options->ca_file_inline,
+                        options->ca_path, options->tls_server);
+    }
+
+    /* Load extra certificates that are part of our own certificate
+     * chain but shouldn't be included in the verify chain */
+    if (options->extra_certs_file)
+    {
+        tls_ctx_load_extra_certs(new_ctx, options->extra_certs_file, options->extra_certs_file_inline);
+    }
+
+    /* Check certificate notBefore and notAfter */
+    tls_ctx_check_cert_time(new_ctx);
+
+    /* Read CRL */
+    if (options->crl_file && !(options->ssl_flags & SSLF_CRL_VERIFY_DIR))
+    {
+        tls_ctx_reload_crl(new_ctx, options->crl_file, options->crl_file_inline);
+    }
+
+    /* Once keys and cert are loaded, load ECDH parameters */
+    if (options->tls_server)
+    {
+        tls_ctx_load_ecdh_params(new_ctx, options->ecdh_curve);
+    }
+
+#ifdef ENABLE_CRYPTO_MBEDTLS
+    /* Personalise the random by mixing in the certificate */
+    tls_ctx_personalise_random(new_ctx);
+#endif
+
+    tls_clear_error();
+    return;
+
+err:
+    tls_clear_error();
+    tls_ctx_free(new_ctx);
+    return;
+}
+
+/*
+ * Map internal constants to ascii names.
+ */
+static const char *
+state_name(int state)
+{
+    switch (state)
+    {
+        case S_UNDEF:
+            return "S_UNDEF";
+
+        case S_INITIAL:
+            return "S_INITIAL";
+
+        case S_PRE_START:
+            return "S_PRE_START";
+
+        case S_START:
+            return "S_START";
+
+        case S_SENT_KEY:
+            return "S_SENT_KEY";
+
+        case S_GOT_KEY:
+            return "S_GOT_KEY";
+
+        case S_ACTIVE:
+            return "S_ACTIVE";
+
+        case S_NORMAL_OP:
+            return "S_NORMAL_OP";
+
+        case S_ERROR:
+            return "S_ERROR";
+
+        default:
+            return "S_???";
+    }
+}
+
+static const char *
+packet_opcode_name(int op)
+{
+    switch (op)
+    {
+        case P_CONTROL_HARD_RESET_CLIENT_V1:
+            return "P_CONTROL_HARD_RESET_CLIENT_V1";
+
+        case P_CONTROL_HARD_RESET_SERVER_V1:
+            return "P_CONTROL_HARD_RESET_SERVER_V1";
+
+        case P_CONTROL_HARD_RESET_CLIENT_V2:
+            return "P_CONTROL_HARD_RESET_CLIENT_V2";
+
+        case P_CONTROL_HARD_RESET_SERVER_V2:
+            return "P_CONTROL_HARD_RESET_SERVER_V2";
+
+        case P_CONTROL_SOFT_RESET_V1:
+            return "P_CONTROL_SOFT_RESET_V1";
+
+        case P_CONTROL_V1:
+            return "P_CONTROL_V1";
+
+        case P_ACK_V1:
+            return "P_ACK_V1";
+
+        case P_DATA_V1:
+            return "P_DATA_V1";
+
+        case P_DATA_V2:
+            return "P_DATA_V2";
+
+        default:
+            return "P_???";
+    }
+}
+
+static const char *
+session_index_name(int index)
+{
+    switch (index)
+    {
+        case TM_ACTIVE:
+            return "TM_ACTIVE";
+
+        case TM_UNTRUSTED:
+            return "TM_UNTRUSTED";
+
+        case TM_LAME_DUCK:
+            return "TM_LAME_DUCK";
+
+        default:
+            return "TM_???";
+    }
+}
+
+/*
+ * For debugging.
+ */
+static const char *
+print_key_id(struct tls_multi *multi, struct gc_arena *gc)
+{
+    int i;
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    for (i = 0; i < KEY_SCAN_SIZE; ++i)
+    {
+        struct key_state *ks = multi->key_scan[i];
+        buf_printf(&out, " [key#%d state=%s id=%d sid=%s]", i,
+                   state_name(ks->state), ks->key_id,
+                   session_id_print(&ks->session_id_remote, gc));
+    }
+
+    return BSTR(&out);
+}
+
+bool
+is_hard_reset(int op, int key_method)
+{
+    if (!key_method || key_method == 1)
+    {
+        if (op == P_CONTROL_HARD_RESET_CLIENT_V1 || op == P_CONTROL_HARD_RESET_SERVER_V1)
+        {
+            return true;
+        }
+    }
+
+    if (!key_method || key_method >= 2)
+    {
+        if (op == P_CONTROL_HARD_RESET_CLIENT_V2 || op == P_CONTROL_HARD_RESET_SERVER_V2)
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/** @addtogroup control_processor
+ *  @{ */
+
+/** @name Functions for initialization and cleanup of key_state structures
+ *  @{ */
+
+/**
+ * Initialize a \c key_state structure.
+ * @ingroup control_processor
+ *
+ * This function initializes a \c key_state structure associated with a \c
+ * tls_session.  It sets up the structure's SSL-BIO, sets the object's \c
+ * key_state.state to \c S_INITIAL, and sets the session ID and key ID two
+ * appropriate values based on the \c tls_session's internal state.  It
+ * also initializes a new set of structures for the \link reliable
+ * Reliability Layer\endlink.
+ *
+ * @param session      - A pointer to the \c tls_session structure
+ *                       associated with the \a ks argument.
+ * @param ks           - A pointer to the \c key_state structure to be
+ *                       initialized.  This structure should already have
+ *                       been allocated before calling this function.
+ */
+static void
+key_state_init(struct tls_session *session, struct key_state *ks)
+{
+    update_time();
+
+    CLEAR(*ks);
+
+    /*
+     * Build TLS object that reads/writes ciphertext
+     * to/from memory BIOs.
+     */
+    key_state_ssl_init(&ks->ks_ssl, &session->opt->ssl_ctx, session->opt->server,
+                       session);
+
+    /* Set control-channel initiation mode */
+    ks->initial_opcode = session->initial_opcode;
+    session->initial_opcode = P_CONTROL_SOFT_RESET_V1;
+    ks->state = S_INITIAL;
+    ks->key_id = session->key_id;
+
+    /*
+     * key_id increments to KEY_ID_MASK then recycles back to 1.
+     * This way you know that if key_id is 0, it is the first key.
+     */
+    ++session->key_id;
+    session->key_id &= P_KEY_ID_MASK;
+    if (!session->key_id)
+    {
+        session->key_id = 1;
+    }
+
+    /* allocate key source material object */
+    ALLOC_OBJ_CLEAR(ks->key_src, struct key_source2);
+
+    /* allocate reliability objects */
+    ALLOC_OBJ_CLEAR(ks->send_reliable, struct reliable);
+    ALLOC_OBJ_CLEAR(ks->rec_reliable, struct reliable);
+    ALLOC_OBJ_CLEAR(ks->rec_ack, struct reliable_ack);
+
+    /* allocate buffers */
+    ks->plaintext_read_buf = alloc_buf(TLS_CHANNEL_BUF_SIZE);
+    ks->plaintext_write_buf = alloc_buf(TLS_CHANNEL_BUF_SIZE);
+    ks->ack_write_buf = alloc_buf(BUF_SIZE(&session->opt->frame));
+    reliable_init(ks->send_reliable, BUF_SIZE(&session->opt->frame),
+                  FRAME_HEADROOM(&session->opt->frame), TLS_RELIABLE_N_SEND_BUFFERS,
+                  ks->key_id ? false : session->opt->xmit_hold);
+    reliable_init(ks->rec_reliable, BUF_SIZE(&session->opt->frame),
+                  FRAME_HEADROOM(&session->opt->frame), TLS_RELIABLE_N_REC_BUFFERS,
+                  false);
+    reliable_set_timeout(ks->send_reliable, session->opt->packet_timeout);
+
+    /* init packet ID tracker */
+    if (session->opt->replay)
+    {
+        packet_id_init(&ks->crypto_options.packet_id,
+                       session->opt->replay_window, session->opt->replay_time, "SSL",
+                       ks->key_id);
+    }
+
+    ks->crypto_options.pid_persist = NULL;
+
+#ifdef MANAGEMENT_DEF_AUTH
+    ks->mda_key_id = session->opt->mda_context->mda_key_id_counter++;
+#endif
+}
+
+
+/**
+ * Cleanup a \c key_state structure.
+ * @ingroup control_processor
+ *
+ * This function cleans up a \c key_state structure.  It frees the
+ * associated SSL-BIO, and the structures allocated for the \link reliable
+ * Reliability Layer\endlink.
+ *
+ * @param ks           - A pointer to the \c key_state structure to be
+ *                       cleaned up.
+ * @param clear        - Whether the memory allocated for the \a ks object
+ *                       should be overwritten with 0s.
+ */
+static void
+key_state_free(struct key_state *ks, bool clear)
+{
+    ks->state = S_UNDEF;
+
+    key_state_ssl_free(&ks->ks_ssl);
+
+    free_key_ctx_bi(&ks->crypto_options.key_ctx_bi);
+    free_buf(&ks->plaintext_read_buf);
+    free_buf(&ks->plaintext_write_buf);
+    free_buf(&ks->ack_write_buf);
+    buffer_list_free(ks->paybuf);
+
+    if (ks->send_reliable)
+    {
+        reliable_free(ks->send_reliable);
+        free(ks->send_reliable);
+    }
+
+    if (ks->rec_reliable)
+    {
+        reliable_free(ks->rec_reliable);
+        free(ks->rec_reliable);
+    }
+
+    if (ks->rec_ack)
+    {
+        free(ks->rec_ack);
+    }
+
+    if (ks->key_src)
+    {
+        free(ks->key_src);
+    }
+
+    packet_id_free(&ks->crypto_options.packet_id);
+
+#ifdef PLUGIN_DEF_AUTH
+    key_state_rm_auth_control_file(ks);
+#endif
+
+    if (clear)
+    {
+        secure_memzero(ks, sizeof(*ks));
+    }
+}
+
+/** @} name Functions for initialization and cleanup of key_state structures */
+
+/** @} addtogroup control_processor */
+
+
+/**
+ * Returns whether or not the server should check for username/password
+ *
+ * @param session       The current TLS session
+ *
+ * @return              true if username and password verification is enabled,
+ *                      false if not.
+ */
+static inline bool
+tls_session_user_pass_enabled(struct tls_session *session)
+{
+    return (session->opt->auth_user_pass_verify_script
+            || plugin_defined(session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY)
+#ifdef MANAGEMENT_DEF_AUTH
+            || management_enable_def_auth(management)
+#endif
+            );
+}
+
+
+/** @addtogroup control_processor
+ *  @{ */
+
+/** @name Functions for initialization and cleanup of tls_session structures
+ *  @{ */
+
+/**
+ * Initialize a \c tls_session structure.
+ * @ingroup control_processor
+ *
+ * This function initializes a \c tls_session structure.  This includes
+ * generating a random session ID, and initializing the \c KS_PRIMARY \c
+ * key_state in the \c tls_session.key array.
+ *
+ * @param multi        - A pointer to the \c tls_multi structure
+ *                       associated with the \a session argument.
+ * @param session      - A pointer to the \c tls_session structure to be
+ *                       initialized.  This structure should already have
+ *                       been allocated before calling this function.
+ */
+static void
+tls_session_init(struct tls_multi *multi, struct tls_session *session)
+{
+    struct gc_arena gc = gc_new();
+
+    dmsg(D_TLS_DEBUG, "TLS: tls_session_init: entry");
+
+    CLEAR(*session);
+
+    /* Set options data to point to parent's option structure */
+    session->opt = &multi->opt;
+
+    /* Randomize session # if it is 0 */
+    while (!session_id_defined(&session->session_id))
+    {
+        session_id_random(&session->session_id);
+    }
+
+    /* Are we a TLS server or client? */
+    ASSERT(session->opt->key_method >= 1);
+    if (session->opt->key_method == 1)
+    {
+        session->initial_opcode = session->opt->server ?
+                                  P_CONTROL_HARD_RESET_SERVER_V1 : P_CONTROL_HARD_RESET_CLIENT_V1;
+    }
+    else /* session->opt->key_method >= 2 */
+    {
+        session->initial_opcode = session->opt->server ?
+                                  P_CONTROL_HARD_RESET_SERVER_V2 : P_CONTROL_HARD_RESET_CLIENT_V2;
+    }
+
+    /* Initialize control channel authentication parameters */
+    session->tls_wrap = session->opt->tls_wrap;
+    session->tls_wrap.work = alloc_buf(BUF_SIZE(&session->opt->frame));
+
+    /* initialize packet ID replay window for --tls-auth */
+    packet_id_init(&session->tls_wrap.opt.packet_id,
+                   session->opt->replay_window,
+                   session->opt->replay_time,
+                   "TLS_WRAP", session->key_id);
+
+    /* load most recent packet-id to replay protect on --tls-auth */
+    packet_id_persist_load_obj(session->tls_wrap.opt.pid_persist,
+                               &session->tls_wrap.opt.packet_id);
+
+    key_state_init(session, &session->key[KS_PRIMARY]);
+
+    dmsg(D_TLS_DEBUG, "TLS: tls_session_init: new session object, sid=%s",
+         session_id_print(&session->session_id, &gc));
+
+    gc_free(&gc);
+}
+
+/**
+ * Clean up a \c tls_session structure.
+ * @ingroup control_processor
+ *
+ * This function cleans up a \c tls_session structure.  This includes
+ * cleaning up all associated \c key_state structures.
+ *
+ * @param session      - A pointer to the \c tls_session structure to be
+ *                       cleaned up.
+ * @param clear        - Whether the memory allocated for the \a session
+ *                       object should be overwritten with 0s.
+ */
+static void
+tls_session_free(struct tls_session *session, bool clear)
+{
+    int i;
+
+    if (packet_id_initialized(&session->tls_wrap.opt.packet_id))
+    {
+        packet_id_free(&session->tls_wrap.opt.packet_id);
+    }
+
+    free_buf(&session->tls_wrap.work);
+
+    for (i = 0; i < KS_SIZE; ++i)
+    {
+        key_state_free(&session->key[i], false);
+    }
+
+    if (session->common_name)
+    {
+        free(session->common_name);
+    }
+
+    cert_hash_free(session->cert_hash_set);
+
+    if (clear)
+    {
+        secure_memzero(session, sizeof(*session));
+    }
+}
+
+/** @} name Functions for initialization and cleanup of tls_session structures */
+
+/** @} addtogroup control_processor */
+
+
+static void
+move_session(struct tls_multi *multi, int dest, int src, bool reinit_src)
+{
+    msg(D_TLS_DEBUG_LOW, "TLS: move_session: dest=%s src=%s reinit_src=%d",
+        session_index_name(dest),
+        session_index_name(src),
+        reinit_src);
+    ASSERT(src != dest);
+    ASSERT(src >= 0 && src < TM_SIZE);
+    ASSERT(dest >= 0 && dest < TM_SIZE);
+    tls_session_free(&multi->session[dest], false);
+    multi->session[dest] = multi->session[src];
+
+    if (reinit_src)
+    {
+        tls_session_init(multi, &multi->session[src]);
+    }
+    else
+    {
+        secure_memzero(&multi->session[src], sizeof(multi->session[src]));
+    }
+
+    dmsg(D_TLS_DEBUG, "TLS: move_session: exit");
+}
+
+static void
+reset_session(struct tls_multi *multi, struct tls_session *session)
+{
+    tls_session_free(session, false);
+    tls_session_init(multi, session);
+}
+
+/*
+ * Used to determine in how many seconds we should be
+ * called again.
+ */
+static inline void
+compute_earliest_wakeup(interval_t *earliest, interval_t seconds_from_now)
+{
+    if (seconds_from_now < *earliest)
+    {
+        *earliest = seconds_from_now;
+    }
+    if (*earliest < 0)
+    {
+        *earliest = 0;
+    }
+}
+
+/*
+ * Return true if "lame duck" or retiring key has expired and can
+ * no longer be used.
+ */
+static inline bool
+lame_duck_must_die(const struct tls_session *session, interval_t *wakeup)
+{
+    const struct key_state *lame = &session->key[KS_LAME_DUCK];
+    if (lame->state >= S_INITIAL)
+    {
+        const time_t local_now = now;
+        ASSERT(lame->must_die); /* a lame duck key must always have an expiration */
+        if (local_now < lame->must_die)
+        {
+            compute_earliest_wakeup(wakeup, lame->must_die - local_now);
+            return false;
+        }
+        else
+        {
+            return true;
+        }
+    }
+    else if (lame->state == S_ERROR)
+    {
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+struct tls_multi *
+tls_multi_init(struct tls_options *tls_options)
+{
+    struct tls_multi *ret;
+
+    ALLOC_OBJ_CLEAR(ret, struct tls_multi);
+
+    /* get command line derived options */
+    ret->opt = *tls_options;
+
+    /* set up list of keys to be scanned by data channel encrypt and decrypt routines */
+    ASSERT(SIZE(ret->key_scan) == 3);
+    ret->key_scan[0] = &ret->session[TM_ACTIVE].key[KS_PRIMARY];
+    ret->key_scan[1] = &ret->session[TM_ACTIVE].key[KS_LAME_DUCK];
+    ret->key_scan[2] = &ret->session[TM_LAME_DUCK].key[KS_LAME_DUCK];
+
+    /* By default not use P_DATA_V2 */
+    ret->use_peer_id = false;
+
+    return ret;
+}
+
+void
+tls_multi_init_finalize(struct tls_multi *multi, const struct frame *frame)
+{
+    tls_init_control_channel_frame_parameters(frame, &multi->opt.frame);
+
+    /* initialize the active and untrusted sessions */
+
+    tls_session_init(multi, &multi->session[TM_ACTIVE]);
+
+    if (!multi->opt.single_session)
+    {
+        tls_session_init(multi, &multi->session[TM_UNTRUSTED]);
+    }
+}
+
+/*
+ * Initialize and finalize a standalone tls-auth verification object.
+ */
+
+struct tls_auth_standalone *
+tls_auth_standalone_init(struct tls_options *tls_options,
+                         struct gc_arena *gc)
+{
+    struct tls_auth_standalone *tas;
+
+    ALLOC_OBJ_CLEAR_GC(tas, struct tls_auth_standalone, gc);
+
+    tas->tls_wrap = tls_options->tls_wrap;
+
+    /*
+     * Standalone tls-auth is in read-only mode with respect to TLS
+     * control channel state.  After we build a new client instance
+     * object, we will process this session-initiating packet for real.
+     */
+    tas->tls_wrap.opt.flags |= CO_IGNORE_PACKET_ID;
+
+    /* get initial frame parms, still need to finalize */
+    tas->frame = tls_options->frame;
+
+    return tas;
+}
+
+void
+tls_auth_standalone_finalize(struct tls_auth_standalone *tas,
+                             const struct frame *frame)
+{
+    tls_init_control_channel_frame_parameters(frame, &tas->frame);
+}
+
+/*
+ * Set local and remote option compatibility strings.
+ * Used to verify compatibility of local and remote option
+ * sets.
+ */
+void
+tls_multi_init_set_options(struct tls_multi *multi,
+                           const char *local,
+                           const char *remote)
+{
+#ifdef ENABLE_OCC
+    /* initialize options string */
+    multi->opt.local_options = local;
+    multi->opt.remote_options = remote;
+#endif
+}
+
+/*
+ * Cleanup a tls_multi structure and free associated memory allocations.
+ */
+void
+tls_multi_free(struct tls_multi *multi, bool clear)
+{
+    int i;
+
+    ASSERT(multi);
+
+#ifdef MANAGEMENT_DEF_AUTH
+    man_def_auth_set_client_reason(multi, NULL);
+
+#endif
+#if P2MP_SERVER
+    free(multi->peer_info);
+#endif
+
+    if (multi->locked_cn)
+    {
+        free(multi->locked_cn);
+    }
+
+    if (multi->locked_username)
+    {
+        free(multi->locked_username);
+    }
+
+    cert_hash_free(multi->locked_cert_hash_set);
+
+    if (multi->auth_token)
+    {
+        secure_memzero(multi->auth_token, AUTH_TOKEN_SIZE);
+        free(multi->auth_token);
+    }
+
+    free(multi->remote_ciphername);
+
+    for (i = 0; i < TM_SIZE; ++i)
+    {
+        tls_session_free(&multi->session[i], false);
+    }
+
+    if (clear)
+    {
+        secure_memzero(multi, sizeof(*multi));
+    }
+
+    free(multi);
+}
+
+
+/*
+ * Move a packet authentication HMAC + related fields to or from the front
+ * of the buffer so it can be processed by encrypt/decrypt.
+ */
+
+/*
+ * Dependent on hmac size, opcode size, and session_id size.
+ * Will assert if too small.
+ */
+#define SWAP_BUF_SIZE 256
+
+static bool
+swap_hmac(struct buffer *buf, const struct crypto_options *co, bool incoming)
+{
+    const struct key_ctx *ctx;
+
+    ASSERT(co);
+
+    ctx = (incoming ? &co->key_ctx_bi.decrypt : &co->key_ctx_bi.encrypt);
+    ASSERT(ctx->hmac);
+
+    {
+        /* hmac + packet_id (8 bytes) */
+        const int hmac_size = hmac_ctx_size(ctx->hmac) + packet_id_size(true);
+
+        /* opcode + session_id */
+        const int osid_size = 1 + SID_SIZE;
+
+        int e1, e2;
+        uint8_t *b = BPTR(buf);
+        uint8_t buf1[SWAP_BUF_SIZE];
+        uint8_t buf2[SWAP_BUF_SIZE];
+
+        if (incoming)
+        {
+            e1 = osid_size;
+            e2 = hmac_size;
+        }
+        else
+        {
+            e1 = hmac_size;
+            e2 = osid_size;
+        }
+
+        ASSERT(e1 <= SWAP_BUF_SIZE && e2 <= SWAP_BUF_SIZE);
+
+        if (buf->len >= e1 + e2)
+        {
+            memcpy(buf1, b, e1);
+            memcpy(buf2, b + e1, e2);
+            memcpy(b, buf2, e2);
+            memcpy(b + e2, buf1, e1);
+            return true;
+        }
+        else
+        {
+            return false;
+        }
+    }
+}
+
+#undef SWAP_BUF_SIZE
+
+/*
+ * Write a control channel authentication record.
+ */
+static void
+write_control_auth(struct tls_session *session,
+                   struct key_state *ks,
+                   struct buffer *buf,
+                   struct link_socket_actual **to_link_addr,
+                   int opcode,
+                   int max_ack,
+                   bool prepend_ack)
+{
+    uint8_t header = ks->key_id | (opcode << P_OPCODE_SHIFT);
+    struct buffer null = clear_buf();
+
+    ASSERT(link_socket_actual_defined(&ks->remote_addr));
+    ASSERT(reliable_ack_write
+               (ks->rec_ack, buf, &ks->session_id_remote, max_ack, prepend_ack));
+
+    if (session->tls_wrap.mode == TLS_WRAP_AUTH
+        || session->tls_wrap.mode == TLS_WRAP_NONE)
+    {
+        ASSERT(session_id_write_prepend(&session->session_id, buf));
+        ASSERT(buf_write_prepend(buf, &header, sizeof(header)));
+    }
+    if (session->tls_wrap.mode == TLS_WRAP_AUTH)
+    {
+        /* no encryption, only write hmac */
+        openvpn_encrypt(buf, null, &session->tls_wrap.opt);
+        ASSERT(swap_hmac(buf, &session->tls_wrap.opt, false));
+    }
+    else if (session->tls_wrap.mode == TLS_WRAP_CRYPT)
+    {
+        ASSERT(buf_init(&session->tls_wrap.work, buf->offset));
+        ASSERT(buf_write(&session->tls_wrap.work, &header, sizeof(header)));
+        ASSERT(session_id_write(&session->session_id, &session->tls_wrap.work));
+        if (tls_crypt_wrap(buf, &session->tls_wrap.work, &session->tls_wrap.opt))
+        {
+            /* Don't change the original data in buf, it's used by the reliability
+             * layer to resend on failure. */
+            *buf = session->tls_wrap.work;
+        }
+        else
+        {
+            buf->len = 0;
+            return;
+        }
+    }
+    *to_link_addr = &ks->remote_addr;
+}
+
+/*
+ * Read a control channel authentication record.
+ */
+static bool
+read_control_auth(struct buffer *buf,
+                  struct tls_wrap_ctx *ctx,
+                  const struct link_socket_actual *from)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+    if (ctx->mode == TLS_WRAP_AUTH)
+    {
+        struct buffer null = clear_buf();
+
+        /* move the hmac record to the front of the packet */
+        if (!swap_hmac(buf, &ctx->opt, true))
+        {
+            msg(D_TLS_ERRORS,
+                "TLS Error: cannot locate HMAC in incoming packet from %s",
+                print_link_socket_actual(from, &gc));
+            gc_free(&gc);
+            return false;
+        }
+
+        /* authenticate only (no decrypt) and remove the hmac record
+         * from the head of the buffer */
+        openvpn_decrypt(buf, null, &ctx->opt, NULL, BPTR(buf));
+        if (!buf->len)
+        {
+            msg(D_TLS_ERRORS,
+                "TLS Error: incoming packet authentication failed from %s",
+                print_link_socket_actual(from, &gc));
+            goto cleanup;
+        }
+
+    }
+    else if (ctx->mode == TLS_WRAP_CRYPT)
+    {
+        struct buffer tmp = alloc_buf_gc(buf_forward_capacity_total(buf), &gc);
+        if (!tls_crypt_unwrap(buf, &tmp, &ctx->opt))
+        {
+            msg(D_TLS_ERRORS, "TLS Error: tls-crypt unwrapping failed from %s",
+                print_link_socket_actual(from, &gc));
+            goto cleanup;
+        }
+        ASSERT(buf_init(buf, buf->offset));
+        ASSERT(buf_copy(buf, &tmp));
+        buf_clear(&tmp);
+    }
+
+    if (ctx->mode == TLS_WRAP_NONE || ctx->mode == TLS_WRAP_AUTH)
+    {
+        /* advance buffer pointer past opcode & session_id since our caller
+         * already read it */
+        buf_advance(buf, SID_SIZE + 1);
+    }
+
+    ret = true;
+cleanup:
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * For debugging, print contents of key_source2 structure.
+ */
+
+static void
+key_source_print(const struct key_source *k,
+                 const char *prefix)
+{
+    struct gc_arena gc = gc_new();
+
+    VALGRIND_MAKE_READABLE((void *)k->pre_master, sizeof(k->pre_master));
+    VALGRIND_MAKE_READABLE((void *)k->random1, sizeof(k->random1));
+    VALGRIND_MAKE_READABLE((void *)k->random2, sizeof(k->random2));
+
+    dmsg(D_SHOW_KEY_SOURCE,
+         "%s pre_master: %s",
+         prefix,
+         format_hex(k->pre_master, sizeof(k->pre_master), 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE,
+         "%s random1: %s",
+         prefix,
+         format_hex(k->random1, sizeof(k->random1), 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE,
+         "%s random2: %s",
+         prefix,
+         format_hex(k->random2, sizeof(k->random2), 0, &gc));
+
+    gc_free(&gc);
+}
+
+static void
+key_source2_print(const struct key_source2 *k)
+{
+    key_source_print(&k->client, "Client");
+    key_source_print(&k->server, "Server");
+}
+
+/*
+ * Generate the hash required by for the \c tls1_PRF function.
+ *
+ * @param md_kt         Message digest to use
+ * @param sec           Secret to base the hash on
+ * @param sec_len       Length of the secret
+ * @param seed          Seed to hash
+ * @param seed_len      Length of the seed
+ * @param out           Output buffer
+ * @param olen          Length of the output buffer
+ */
+static void
+tls1_P_hash(const md_kt_t *md_kt,
+            const uint8_t *sec,
+            int sec_len,
+            const uint8_t *seed,
+            int seed_len,
+            uint8_t *out,
+            int olen)
+{
+    struct gc_arena gc = gc_new();
+    int chunk;
+    hmac_ctx_t *ctx;
+    hmac_ctx_t *ctx_tmp;
+    uint8_t A1[MAX_HMAC_KEY_LENGTH];
+    unsigned int A1_len;
+
+#ifdef ENABLE_DEBUG
+    const int olen_orig = olen;
+    const uint8_t *out_orig = out;
+#endif
+
+    ctx = hmac_ctx_new();
+    ctx_tmp = hmac_ctx_new();
+
+    dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash sec: %s", format_hex(sec, sec_len, 0, &gc));
+    dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash seed: %s", format_hex(seed, seed_len, 0, &gc));
+
+    chunk = md_kt_size(md_kt);
+    A1_len = md_kt_size(md_kt);
+
+    hmac_ctx_init(ctx, sec, sec_len, md_kt);
+    hmac_ctx_init(ctx_tmp, sec, sec_len, md_kt);
+
+    hmac_ctx_update(ctx,seed,seed_len);
+    hmac_ctx_final(ctx, A1);
+
+    for (;; )
+    {
+        hmac_ctx_reset(ctx);
+        hmac_ctx_reset(ctx_tmp);
+        hmac_ctx_update(ctx,A1,A1_len);
+        hmac_ctx_update(ctx_tmp,A1,A1_len);
+        hmac_ctx_update(ctx,seed,seed_len);
+
+        if (olen > chunk)
+        {
+            hmac_ctx_final(ctx, out);
+            out += chunk;
+            olen -= chunk;
+            hmac_ctx_final(ctx_tmp, A1); /* calc the next A1 value */
+        }
+        else    /* last one */
+        {
+            hmac_ctx_final(ctx, A1);
+            memcpy(out,A1,olen);
+            break;
+        }
+    }
+    hmac_ctx_cleanup(ctx);
+    hmac_ctx_free(ctx);
+    hmac_ctx_cleanup(ctx_tmp);
+    hmac_ctx_free(ctx_tmp);
+    secure_memzero(A1, sizeof(A1));
+
+    dmsg(D_SHOW_KEY_SOURCE, "tls1_P_hash out: %s", format_hex(out_orig, olen_orig, 0, &gc));
+    gc_free(&gc);
+}
+
+/*
+ * Use the TLS PRF function for generating data channel keys.
+ * This code is based on the OpenSSL library.
+ *
+ * TLS generates keys as such:
+ *
+ * master_secret[48] = PRF(pre_master_secret[48], "master secret",
+ *                         ClientHello.random[32] + ServerHello.random[32])
+ *
+ * key_block[] = PRF(SecurityParameters.master_secret[48],
+ *                 "key expansion",
+ *                 SecurityParameters.server_random[32] +
+ *                 SecurityParameters.client_random[32]);
+ *
+ * Notes:
+ *
+ * (1) key_block contains a full set of 4 keys.
+ * (2) The pre-master secret is generated by the client.
+ */
+static void
+tls1_PRF(const uint8_t *label,
+         int label_len,
+         const uint8_t *sec,
+         int slen,
+         uint8_t *out1,
+         int olen)
+{
+    struct gc_arena gc = gc_new();
+    const md_kt_t *md5 = md_kt_get("MD5");
+    const md_kt_t *sha1 = md_kt_get("SHA1");
+    int len,i;
+    const uint8_t *S1,*S2;
+    uint8_t *out2;
+
+    out2 = (uint8_t *) gc_malloc(olen, false, &gc);
+
+    len = slen/2;
+    S1 = sec;
+    S2 = &(sec[len]);
+    len += (slen&1); /* add for odd, make longer */
+
+    tls1_P_hash(md5,S1,len,label,label_len,out1,olen);
+    tls1_P_hash(sha1,S2,len,label,label_len,out2,olen);
+
+    for (i = 0; i<olen; i++)
+    {
+        out1[i] ^= out2[i];
+    }
+
+    secure_memzero(out2, olen);
+
+    dmsg(D_SHOW_KEY_SOURCE, "tls1_PRF out[%d]: %s", olen, format_hex(out1, olen, 0, &gc));
+
+    gc_free(&gc);
+}
+
+static void
+openvpn_PRF(const uint8_t *secret,
+            int secret_len,
+            const char *label,
+            const uint8_t *client_seed,
+            int client_seed_len,
+            const uint8_t *server_seed,
+            int server_seed_len,
+            const struct session_id *client_sid,
+            const struct session_id *server_sid,
+            uint8_t *output,
+            int output_len)
+{
+    /* concatenate seed components */
+
+    struct buffer seed = alloc_buf(strlen(label)
+                                   + client_seed_len
+                                   + server_seed_len
+                                   + SID_SIZE * 2);
+
+    ASSERT(buf_write(&seed, label, strlen(label)));
+    ASSERT(buf_write(&seed, client_seed, client_seed_len));
+    ASSERT(buf_write(&seed, server_seed, server_seed_len));
+
+    if (client_sid)
+    {
+        ASSERT(buf_write(&seed, client_sid->id, SID_SIZE));
+    }
+    if (server_sid)
+    {
+        ASSERT(buf_write(&seed, server_sid->id, SID_SIZE));
+    }
+
+    /* compute PRF */
+    tls1_PRF(BPTR(&seed), BLEN(&seed), secret, secret_len, output, output_len);
+
+    buf_clear(&seed);
+    free_buf(&seed);
+
+    VALGRIND_MAKE_READABLE((void *)output, output_len);
+}
+
+/*
+ * Using source entropy from local and remote hosts, mix into
+ * master key.
+ */
+static bool
+generate_key_expansion(struct key_ctx_bi *key,
+                       const struct key_type *key_type,
+                       const struct key_source2 *key_src,
+                       const struct session_id *client_sid,
+                       const struct session_id *server_sid,
+                       bool server)
+{
+    uint8_t master[48] = { 0 };
+    struct key2 key2 = { 0 };
+    bool ret = false;
+
+    if (key->initialized)
+    {
+        msg(D_TLS_ERRORS, "TLS Error: key already initialized");
+        goto exit;
+    }
+
+    /* debugging print of source key material */
+    key_source2_print(key_src);
+
+    /* compute master secret */
+    openvpn_PRF(key_src->client.pre_master,
+                sizeof(key_src->client.pre_master),
+                KEY_EXPANSION_ID " master secret",
+                key_src->client.random1,
+                sizeof(key_src->client.random1),
+                key_src->server.random1,
+                sizeof(key_src->server.random1),
+                NULL,
+                NULL,
+                master,
+                sizeof(master));
+
+    /* compute key expansion */
+    openvpn_PRF(master,
+                sizeof(master),
+                KEY_EXPANSION_ID " key expansion",
+                key_src->client.random2,
+                sizeof(key_src->client.random2),
+                key_src->server.random2,
+                sizeof(key_src->server.random2),
+                client_sid,
+                server_sid,
+                (uint8_t *)key2.keys,
+                sizeof(key2.keys));
+
+    key2.n = 2;
+
+    key2_print(&key2, key_type, "Master Encrypt", "Master Decrypt");
+
+    /* check for weak keys */
+    for (int i = 0; i < 2; ++i)
+    {
+        fixup_key(&key2.keys[i], key_type);
+        if (!check_key(&key2.keys[i], key_type))
+        {
+            msg(D_TLS_ERRORS, "TLS Error: Bad dynamic key generated");
+            goto exit;
+        }
+    }
+
+    /* Initialize OpenSSL key contexts */
+    int key_direction = server ? KEY_DIRECTION_INVERSE : KEY_DIRECTION_NORMAL;
+    init_key_ctx_bi(key, &key2, key_direction, key_type, "Data Channel");
+
+    /* Initialize implicit IVs */
+    key_ctx_update_implicit_iv(&key->encrypt, key2.keys[(int)server].hmac,
+                               MAX_HMAC_KEY_LENGTH);
+    key_ctx_update_implicit_iv(&key->decrypt, key2.keys[1-(int)server].hmac,
+                               MAX_HMAC_KEY_LENGTH);
+
+    ret = true;
+
+exit:
+    secure_memzero(&master, sizeof(master));
+    secure_memzero(&key2, sizeof(key2));
+
+    return ret;
+}
+
+static void
+key_ctx_update_implicit_iv(struct key_ctx *ctx, uint8_t *key, size_t key_len)
+{
+    const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt(ctx->cipher);
+
+    /* Only use implicit IV in AEAD cipher mode, where HMAC key is not used */
+    if (cipher_kt_mode_aead(cipher_kt))
+    {
+        size_t impl_iv_len = 0;
+        ASSERT(cipher_kt_iv_size(cipher_kt) >= OPENVPN_AEAD_MIN_IV_LEN);
+        impl_iv_len = cipher_kt_iv_size(cipher_kt) - sizeof(packet_id_type);
+        ASSERT(impl_iv_len <= OPENVPN_MAX_IV_LENGTH);
+        ASSERT(impl_iv_len <= key_len);
+        memcpy(ctx->implicit_iv, key, impl_iv_len);
+        ctx->implicit_iv_len = impl_iv_len;
+    }
+}
+
+bool
+tls_item_in_cipher_list(const char *item, const char *list)
+{
+    char *tmp_ciphers = string_alloc(list, NULL);
+    char *tmp_ciphers_orig = tmp_ciphers;
+
+    const char *token = strtok(tmp_ciphers, ":");
+    while (token)
+    {
+        if (0 == strcmp(token, item))
+        {
+            break;
+        }
+        token = strtok(NULL, ":");
+    }
+    free(tmp_ciphers_orig);
+
+    return token != NULL;
+}
+
+void
+tls_poor_mans_ncp(struct options *o, const char *remote_ciphername)
+{
+    if (o->ncp_enabled && remote_ciphername
+        && 0 != strcmp(o->ciphername, remote_ciphername))
+    {
+        if (tls_item_in_cipher_list(remote_ciphername, o->ncp_ciphers))
+        {
+            o->ciphername = string_alloc(remote_ciphername, &o->gc);
+            msg(D_TLS_DEBUG_LOW, "Using peer cipher '%s'", o->ciphername);
+        }
+    }
+}
+
+/**
+ * Generate data channel keys for the supplied TLS session.
+ *
+ * This erases the source material used to generate the data channel keys, and
+ * can thus be called only once per session.
+ */
+static bool
+tls_session_generate_data_channel_keys(struct tls_session *session)
+{
+    bool ret = false;
+    struct key_state *ks = &session->key[KS_PRIMARY];   /* primary key */
+    const struct session_id *client_sid = session->opt->server ?
+                                          &ks->session_id_remote : &session->session_id;
+    const struct session_id *server_sid = !session->opt->server ?
+                                          &ks->session_id_remote : &session->session_id;
+
+    ASSERT(ks->authenticated);
+
+    ks->crypto_options.flags = session->opt->crypto_flags;
+    if (!generate_key_expansion(&ks->crypto_options.key_ctx_bi,
+                                &session->opt->key_type, ks->key_src, client_sid, server_sid,
+                                session->opt->server))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: generate_key_expansion failed");
+        goto cleanup;
+    }
+    tls_limit_reneg_bytes(session->opt->key_type.cipher,
+                          &session->opt->renegotiate_bytes);
+
+    ret = true;
+cleanup:
+    secure_memzero(ks->key_src, sizeof(*ks->key_src));
+    return ret;
+}
+
+bool
+tls_session_update_crypto_params(struct tls_session *session,
+                                 struct options *options, struct frame *frame,
+                                 struct frame *frame_fragment)
+{
+    if (session->key[KS_PRIMARY].crypto_options.key_ctx_bi.initialized)
+    {
+        /* keys already generated, nothing to do */
+        return true;
+    }
+
+    if (!session->opt->server
+        && 0 != strcmp(options->ciphername, session->opt->config_ciphername)
+        && !tls_item_in_cipher_list(options->ciphername, options->ncp_ciphers))
+    {
+        msg(D_TLS_ERRORS, "Error: pushed cipher not allowed - %s not in %s or %s",
+            options->ciphername, session->opt->config_ciphername,
+            options->ncp_ciphers);
+        /* undo cipher push, abort connection setup */
+        options->ciphername = session->opt->config_ciphername;
+        return false;
+    }
+
+    if (strcmp(options->ciphername, session->opt->config_ciphername))
+    {
+        msg(D_HANDSHAKE, "Data Channel: using negotiated cipher '%s'",
+            options->ciphername);
+        if (options->keysize)
+        {
+            msg(D_HANDSHAKE, "NCP: overriding user-set keysize with default");
+            options->keysize = 0;
+        }
+    }
+
+    init_key_type(&session->opt->key_type, options->ciphername,
+                  options->authname, options->keysize, true, true);
+
+    bool packet_id_long_form = cipher_kt_mode_ofb_cfb(session->opt->key_type.cipher);
+    session->opt->crypto_flags &= ~(CO_PACKET_ID_LONG_FORM);
+    if (packet_id_long_form)
+    {
+        session->opt->crypto_flags |= CO_PACKET_ID_LONG_FORM;
+    }
+
+    /* Update frame parameters: undo worst-case overhead, add actual overhead */
+    frame_remove_from_extra_frame(frame, crypto_max_overhead());
+    crypto_adjust_frame_parameters(frame, &session->opt->key_type,
+                                   options->use_iv, options->replay, packet_id_long_form);
+    frame_finalize(frame, options->ce.link_mtu_defined, options->ce.link_mtu,
+                   options->ce.tun_mtu_defined, options->ce.tun_mtu);
+    frame_init_mssfix(frame, options);
+    frame_print(frame, D_MTU_INFO, "Data Channel MTU parms");
+
+    /*
+     * mssfix uses data channel framing, which at this point contains
+     * actual overhead. Fragmentation logic uses frame_fragment, which
+     * still contains worst case overhead. Replace it with actual overhead
+     * to prevent unneeded fragmentation.
+     */
+
+    if (frame_fragment)
+    {
+        frame_remove_from_extra_frame(frame_fragment, crypto_max_overhead());
+        crypto_adjust_frame_parameters(frame_fragment, &session->opt->key_type,
+                                       options->use_iv, options->replay, packet_id_long_form);
+        frame_set_mtu_dynamic(frame_fragment, options->ce.fragment, SET_MTU_UPPER_BOUND);
+        frame_print(frame_fragment, D_MTU_INFO, "Fragmentation MTU parms");
+    }
+
+    return tls_session_generate_data_channel_keys(session);
+}
+
+static bool
+random_bytes_to_buf(struct buffer *buf,
+                    uint8_t *out,
+                    int outlen)
+{
+    if (!rand_bytes(out, outlen))
+    {
+        msg(M_FATAL, "ERROR: Random number generator cannot obtain entropy for key generation [SSL]");
+    }
+    if (!buf_write(buf, out, outlen))
+    {
+        return false;
+    }
+    return true;
+}
+
+static bool
+key_source2_randomize_write(struct key_source2 *k2,
+                            struct buffer *buf,
+                            bool server)
+{
+    struct key_source *k = &k2->client;
+    if (server)
+    {
+        k = &k2->server;
+    }
+
+    CLEAR(*k);
+
+    if (!server)
+    {
+        if (!random_bytes_to_buf(buf, k->pre_master, sizeof(k->pre_master)))
+        {
+            return false;
+        }
+    }
+
+    if (!random_bytes_to_buf(buf, k->random1, sizeof(k->random1)))
+    {
+        return false;
+    }
+    if (!random_bytes_to_buf(buf, k->random2, sizeof(k->random2)))
+    {
+        return false;
+    }
+
+    return true;
+}
+
+static int
+key_source2_read(struct key_source2 *k2,
+                 struct buffer *buf,
+                 bool server)
+{
+    struct key_source *k = &k2->client;
+
+    if (!server)
+    {
+        k = &k2->server;
+    }
+
+    CLEAR(*k);
+
+    if (server)
+    {
+        if (!buf_read(buf, k->pre_master, sizeof(k->pre_master)))
+        {
+            return 0;
+        }
+    }
+
+    if (!buf_read(buf, k->random1, sizeof(k->random1)))
+    {
+        return 0;
+    }
+    if (!buf_read(buf, k->random2, sizeof(k->random2)))
+    {
+        return 0;
+    }
+
+    return 1;
+}
+
+static void
+flush_payload_buffer(struct key_state *ks)
+{
+    struct buffer *b;
+
+    while ((b = buffer_list_peek(ks->paybuf)))
+    {
+        key_state_write_plaintext_const(&ks->ks_ssl, b->data, b->len);
+        buffer_list_pop(ks->paybuf);
+    }
+}
+
+/* true if no in/out acknowledgements pending */
+#define FULL_SYNC \
+    (reliable_empty(ks->send_reliable) && reliable_ack_empty(ks->rec_ack))
+
+/*
+ * Move the active key to the lame duck key and reinitialize the
+ * active key.
+ */
+static void
+key_state_soft_reset(struct tls_session *session)
+{
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+    struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
+
+    ks->must_die = now + session->opt->transition_window; /* remaining lifetime of old key */
+    key_state_free(ks_lame, false);
+    *ks_lame = *ks;
+
+    key_state_init(session, ks);
+    ks->session_id_remote = ks_lame->session_id_remote;
+    ks->remote_addr = ks_lame->remote_addr;
+}
+
+/*
+ * Read/write strings from/to a struct buffer with a u16 length prefix.
+ */
+
+static bool
+write_empty_string(struct buffer *buf)
+{
+    if (!buf_write_u16(buf, 0))
+    {
+        return false;
+    }
+    return true;
+}
+
+static bool
+write_string(struct buffer *buf, const char *str, const int maxlen)
+{
+    const int len = strlen(str) + 1;
+    if (len < 1 || (maxlen >= 0 && len > maxlen))
+    {
+        return false;
+    }
+    if (!buf_write_u16(buf, len))
+    {
+        return false;
+    }
+    if (!buf_write(buf, str, len))
+    {
+        return false;
+    }
+    return true;
+}
+
+static bool
+read_string(struct buffer *buf, char *str, const unsigned int capacity)
+{
+    const int len = buf_read_u16(buf);
+    if (len < 1 || len > (int)capacity)
+    {
+        return false;
+    }
+    if (!buf_read(buf, str, len))
+    {
+        return false;
+    }
+    str[len-1] = '\0';
+    return true;
+}
+
+static char *
+read_string_alloc(struct buffer *buf)
+{
+    const int len = buf_read_u16(buf);
+    char *str;
+
+    if (len < 1)
+    {
+        return NULL;
+    }
+    str = (char *) malloc(len);
+    check_malloc_return(str);
+    if (!buf_read(buf, str, len))
+    {
+        free(str);
+        return NULL;
+    }
+    str[len-1] = '\0';
+    return str;
+}
+
+/*
+ * Handle the reading and writing of key data to and from
+ * the TLS control channel (cleartext).
+ */
+
+static bool
+key_method_1_write(struct buffer *buf, struct tls_session *session)
+{
+    struct key key;
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    ASSERT(session->opt->key_method == 1);
+    ASSERT(buf_init(buf, 0));
+
+    generate_key_random(&key, &session->opt->key_type);
+    if (!check_key(&key, &session->opt->key_type))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Bad encrypting key generated");
+        return false;
+    }
+
+    if (!write_key(&key, &session->opt->key_type, buf))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: write_key failed");
+        return false;
+    }
+
+    init_key_ctx(&ks->crypto_options.key_ctx_bi.encrypt, &key,
+                 &session->opt->key_type, OPENVPN_OP_ENCRYPT,
+                 "Data Channel Encrypt");
+    secure_memzero(&key, sizeof(key));
+
+    /* send local options string */
+    {
+        const char *local_options = local_options_string(session);
+        const int optlen = strlen(local_options) + 1;
+        if (!buf_write(buf, local_options, optlen))
+        {
+            msg(D_TLS_ERRORS, "TLS Error: KM1 write options failed");
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static bool
+push_peer_info(struct buffer *buf, struct tls_session *session)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+#ifdef ENABLE_PUSH_PEER_INFO
+    if (session->opt->push_peer_info_detail > 0)
+    {
+        struct env_set *es = session->opt->es;
+        struct env_item *e;
+        struct buffer out = alloc_buf_gc(512*3, &gc);
+
+        /* push version */
+        buf_printf(&out, "IV_VER=%s\n", PACKAGE_VERSION);
+
+        /* push platform */
+#if defined(TARGET_LINUX)
+        buf_printf(&out, "IV_PLAT=linux\n");
+#elif defined(TARGET_SOLARIS)
+        buf_printf(&out, "IV_PLAT=solaris\n");
+#elif defined(TARGET_OPENBSD)
+        buf_printf(&out, "IV_PLAT=openbsd\n");
+#elif defined(TARGET_DARWIN)
+        buf_printf(&out, "IV_PLAT=mac\n");
+#elif defined(TARGET_NETBSD)
+        buf_printf(&out, "IV_PLAT=netbsd\n");
+#elif defined(TARGET_FREEBSD)
+        buf_printf(&out, "IV_PLAT=freebsd\n");
+#elif defined(TARGET_ANDROID)
+        buf_printf(&out, "IV_PLAT=android\n");
+#elif defined(_WIN32)
+        buf_printf(&out, "IV_PLAT=win\n");
+#endif
+
+        /* support for P_DATA_V2 */
+        buf_printf(&out, "IV_PROTO=2\n");
+
+        /* support for Negotiable Crypto Paramters */
+        if (session->opt->ncp_enabled
+            && (session->opt->mode == MODE_SERVER || session->opt->pull))
+        {
+            buf_printf(&out, "IV_NCP=2\n");
+        }
+
+        /* push compression status */
+#ifdef USE_COMP
+        comp_generate_peer_info_string(&session->opt->comp_options, &out);
+#endif
+
+        if (session->opt->push_peer_info_detail >= 2)
+        {
+            /* push mac addr */
+            struct route_gateway_info rgi;
+            get_default_gateway(&rgi);
+            if (rgi.flags & RGI_HWADDR_DEFINED)
+            {
+                buf_printf(&out, "IV_HWADDR=%s\n", format_hex_ex(rgi.hwaddr, 6, 0, 1, ":", &gc));
+            }
+            buf_printf(&out, "IV_SSL=%s\n", get_ssl_library_version() );
+#if defined(_WIN32)
+            buf_printf(&out, "IV_PLAT_VER=%s\n", win32_version_string(&gc, false));
+#endif
+        }
+
+        /* push env vars that begin with UV_, IV_PLAT_VER and IV_GUI_VER */
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            if (e->string)
+            {
+                if ((((strncmp(e->string, "UV_", 3)==0
+                       || strncmp(e->string, "IV_PLAT_VER=", sizeof("IV_PLAT_VER=")-1)==0)
+                      && session->opt->push_peer_info_detail >= 2)
+                     || (strncmp(e->string,"IV_GUI_VER=",sizeof("IV_GUI_VER=")-1)==0))
+                    && buf_safe(&out, strlen(e->string)+1))
+                {
+                    buf_printf(&out, "%s\n", e->string);
+                }
+            }
+        }
+
+        if (!write_string(buf, BSTR(&out), -1))
+        {
+            goto error;
+        }
+    }
+    else
+#endif /* ifdef ENABLE_PUSH_PEER_INFO */
+    {
+        if (!write_empty_string(buf)) /* no peer info */
+        {
+            goto error;
+        }
+    }
+    ret = true;
+
+error:
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+key_method_2_write(struct buffer *buf, struct tls_session *session)
+{
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    ASSERT(session->opt->key_method == 2);
+    ASSERT(buf_init(buf, 0));
+
+    /* write a uint32 0 */
+    if (!buf_write_u32(buf, 0))
+    {
+        goto error;
+    }
+
+    /* write key_method + flags */
+    if (!buf_write_u8(buf, (session->opt->key_method & KEY_METHOD_MASK)))
+    {
+        goto error;
+    }
+
+    /* write key source material */
+    if (!key_source2_randomize_write(ks->key_src, buf, session->opt->server))
+    {
+        goto error;
+    }
+
+    /* write options string */
+    {
+        if (!write_string(buf, local_options_string(session), TLS_OPTIONS_LEN))
+        {
+            goto error;
+        }
+    }
+
+    /* write username/password if specified */
+    if (auth_user_pass_enabled)
+    {
+#ifdef ENABLE_CLIENT_CR
+        auth_user_pass_setup(session->opt->auth_user_pass_file, session->opt->sci);
+#else
+        auth_user_pass_setup(session->opt->auth_user_pass_file, NULL);
+#endif
+        struct user_pass *up = &auth_user_pass;
+
+        /*
+         * If we have a valid auth-token, send that instead of real
+         * username/password
+         */
+        if (auth_token.defined)
+            up = &auth_token;
+
+        if (!write_string(buf, up->username, -1))
+        {
+            goto error;
+        }
+        else if (!write_string(buf, up->password, -1))
+        {
+            goto error;
+        }
+        /* if auth-nocache was specified, the auth_user_pass object reaches
+         * a "complete" state only after having received the push-reply
+         * message.
+         *
+         * For this reason, skip the purge operation here if no push-reply
+         * message has been received yet.
+         *
+         * This normally happens upon first negotiation only.
+         */
+        if (!auth_user_pass.wait_for_push)
+        {
+            purge_user_pass(&auth_user_pass, false);
+        }
+    }
+    else
+    {
+        if (!write_empty_string(buf)) /* no username */
+        {
+            goto error;
+        }
+        if (!write_empty_string(buf)) /* no password */
+        {
+            goto error;
+        }
+    }
+
+    if (!push_peer_info(buf, session))
+    {
+        goto error;
+    }
+
+    /* Generate tunnel keys if we're a TLS server.
+     * If we're a p2mp server and IV_NCP >= 2 is negotiated, the first key
+     * generation is postponed until after the pull/push, so we can process pushed
+     * cipher directives.
+     */
+    if (session->opt->server && !(session->opt->ncp_enabled
+                                  && session->opt->mode == MODE_SERVER && ks->key_id <= 0))
+    {
+        if (ks->authenticated)
+        {
+            if (!tls_session_generate_data_channel_keys(session))
+            {
+                msg(D_TLS_ERRORS, "TLS Error: server generate_key_expansion failed");
+                goto error;
+            }
+        }
+    }
+
+    return true;
+
+error:
+    msg(D_TLS_ERRORS, "TLS Error: Key Method #2 write failed");
+    secure_memzero(ks->key_src, sizeof(*ks->key_src));
+    return false;
+}
+
+static bool
+key_method_1_read(struct buffer *buf, struct tls_session *session)
+{
+    int status;
+    struct key key;
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    ASSERT(session->opt->key_method == 1);
+
+    if (!session->verified)
+    {
+        msg(D_TLS_ERRORS,
+            "TLS Error: Certificate verification failed (key-method 1)");
+        goto error;
+    }
+
+    status = read_key(&key, &session->opt->key_type, buf);
+    if (status != 1)
+    {
+        msg(D_TLS_ERRORS,
+            "TLS Error: Error reading data channel key from plaintext buffer");
+        goto error;
+    }
+
+    if (!check_key(&key, &session->opt->key_type))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Bad decrypting key received from peer");
+        goto error;
+    }
+
+    if (buf->len < 1)
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Missing options string");
+        goto error;
+    }
+
+#ifdef ENABLE_OCC
+    /* compare received remote options string
+     * with our locally computed options string */
+    if (!session->opt->disable_occ
+        && !options_cmp_equal_safe((char *) BPTR(buf), session->opt->remote_options, buf->len))
+    {
+        options_warning_safe((char *) BPTR(buf), session->opt->remote_options, buf->len);
+    }
+#endif
+
+    buf_clear(buf);
+
+    init_key_ctx(&ks->crypto_options.key_ctx_bi.decrypt, &key,
+                 &session->opt->key_type, OPENVPN_OP_DECRYPT,
+                 "Data Channel Decrypt");
+    secure_memzero(&key, sizeof(key));
+    ks->authenticated = true;
+    return true;
+
+error:
+    buf_clear(buf);
+    secure_memzero(&key, sizeof(key));
+    return false;
+}
+
+static bool
+key_method_2_read(struct buffer *buf, struct tls_multi *multi, struct tls_session *session)
+{
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    int key_method_flags;
+    bool username_status, password_status;
+
+    struct gc_arena gc = gc_new();
+    char *options;
+    struct user_pass *up = NULL;
+
+    /* allocate temporary objects */
+    ALLOC_ARRAY_CLEAR_GC(options, char, TLS_OPTIONS_LEN, &gc);
+
+    ASSERT(session->opt->key_method == 2);
+
+    /* discard leading uint32 */
+    if (!buf_advance(buf, 4))
+    {
+        msg(D_TLS_ERRORS, "TLS ERROR: Plaintext buffer too short (%d bytes).",
+            buf->len);
+        goto error;
+    }
+
+    /* get key method */
+    key_method_flags = buf_read_u8(buf);
+    if ((key_method_flags & KEY_METHOD_MASK) != 2)
+    {
+        msg(D_TLS_ERRORS,
+            "TLS ERROR: Unknown key_method/flags=%d received from remote host",
+            key_method_flags);
+        goto error;
+    }
+
+    /* get key source material (not actual keys yet) */
+    if (!key_source2_read(ks->key_src, buf, session->opt->server))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Error reading remote data channel key source entropy from plaintext buffer");
+        goto error;
+    }
+
+    /* get options */
+    if (!read_string(buf, options, TLS_OPTIONS_LEN))
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Failed to read required OCC options string");
+        goto error;
+    }
+
+    ks->authenticated = false;
+
+    /* always extract username + password fields from buf, even if not
+     * authenticating for it, because otherwise we can't get at the
+     * peer_info data which follows behind
+     */
+    ALLOC_OBJ_CLEAR_GC(up, struct user_pass, &gc);
+    username_status = read_string(buf, up->username, USER_PASS_LEN);
+    password_status = read_string(buf, up->password, USER_PASS_LEN);
+
+#if P2MP_SERVER
+    /* get peer info from control channel */
+    free(multi->peer_info);
+    multi->peer_info = read_string_alloc(buf);
+    if (multi->peer_info)
+    {
+        output_peer_info_env(session->opt->es, multi->peer_info);
+    }
+
+    free(multi->remote_ciphername);
+    multi->remote_ciphername =
+        options_string_extract_option(options, "cipher", NULL);
+
+    if (tls_peer_info_ncp_ver(multi->peer_info) < 2)
+    {
+        /* Peer does not support NCP, but leave NCP enabled if the local and
+         * remote cipher do not match to attempt 'poor-man's NCP'.
+         */
+        if (multi->remote_ciphername == NULL
+            || 0 == strcmp(multi->remote_ciphername, multi->opt.config_ciphername))
+        {
+            session->opt->ncp_enabled = false;
+        }
+    }
+#endif /* if P2MP_SERVER */
+
+    if (tls_session_user_pass_enabled(session))
+    {
+        /* Perform username/password authentication */
+        if (!username_status || !password_status)
+        {
+            CLEAR(*up);
+            if (!(session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL))
+            {
+                msg(D_TLS_ERRORS, "TLS Error: Auth Username/Password was not provided by peer");
+                goto error;
+            }
+        }
+
+        verify_user_pass(up, multi, session);
+    }
+    else
+    {
+        /* Session verification should have occurred during TLS negotiation*/
+        if (!session->verified)
+        {
+            msg(D_TLS_ERRORS,
+                "TLS Error: Certificate verification failed (key-method 2)");
+            goto error;
+        }
+        ks->authenticated = true;
+    }
+
+    /* clear username and password from memory */
+    secure_memzero(up, sizeof(*up));
+
+    /* Perform final authentication checks */
+    if (ks->authenticated)
+    {
+        verify_final_auth_checks(multi, session);
+    }
+
+#ifdef ENABLE_OCC
+    /* check options consistency */
+    if (!session->opt->disable_occ
+        && !options_cmp_equal(options, session->opt->remote_options))
+    {
+        options_warning(options, session->opt->remote_options);
+        if (session->opt->ssl_flags & SSLF_OPT_VERIFY)
+        {
+            msg(D_TLS_ERRORS, "Option inconsistency warnings triggering disconnect due to --opt-verify");
+            ks->authenticated = false;
+        }
+    }
+#endif
+
+    buf_clear(buf);
+
+    /*
+     * Call OPENVPN_PLUGIN_TLS_FINAL plugin if defined, for final
+     * veto opportunity over authentication decision.
+     */
+    if (ks->authenticated && plugin_defined(session->opt->plugins, OPENVPN_PLUGIN_TLS_FINAL))
+    {
+        key_state_export_keying_material(&ks->ks_ssl, session);
+
+        if (plugin_call(session->opt->plugins, OPENVPN_PLUGIN_TLS_FINAL, NULL, NULL, session->opt->es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            ks->authenticated = false;
+        }
+
+        setenv_del(session->opt->es, "exported_keying_material");
+    }
+
+    /*
+     * Generate tunnel keys if we're a client.
+     * If --pull is enabled, the first key generation is postponed until after the
+     * pull/push, so we can process pushed cipher directives.
+     */
+    if (!session->opt->server && (!session->opt->pull || ks->key_id > 0))
+    {
+        if (!tls_session_generate_data_channel_keys(session))
+        {
+            msg(D_TLS_ERRORS, "TLS Error: client generate_key_expansion failed");
+            goto error;
+        }
+    }
+
+    gc_free(&gc);
+    return true;
+
+error:
+    secure_memzero(ks->key_src, sizeof(*ks->key_src));
+    if (up)
+    {
+        secure_memzero(up, sizeof(*up));
+    }
+    buf_clear(buf);
+    gc_free(&gc);
+    return false;
+}
+
+static int
+auth_deferred_expire_window(const struct tls_options *o)
+{
+    int ret = o->handshake_window;
+    const int r2 = o->renegotiate_seconds / 2;
+
+    if (o->renegotiate_seconds && r2 < ret)
+    {
+        ret = r2;
+    }
+    return ret;
+}
+
+/*
+ * This is the primary routine for processing TLS stuff inside the
+ * the main event loop.  When this routine exits
+ * with non-error status, it will set *wakeup to the number of seconds
+ * when it wants to be called again.
+ *
+ * Return value is true if we have placed a packet in *to_link which we
+ * want to send to our peer.
+ */
+static bool
+tls_process(struct tls_multi *multi,
+            struct tls_session *session,
+            struct buffer *to_link,
+            struct link_socket_actual **to_link_addr,
+            struct link_socket_info *to_link_socket_info,
+            interval_t *wakeup)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer *buf;
+    bool state_change = false;
+    bool active = false;
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+    struct key_state *ks_lame = &session->key[KS_LAME_DUCK]; /* retiring key */
+
+    /* Make sure we were initialized and that we're not in an error state */
+    ASSERT(ks->state != S_UNDEF);
+    ASSERT(ks->state != S_ERROR);
+    ASSERT(session_id_defined(&session->session_id));
+
+    /* Should we trigger a soft reset? -- new key, keeps old key for a while */
+    if (ks->state >= S_ACTIVE
+        && ((session->opt->renegotiate_seconds
+             && now >= ks->established + session->opt->renegotiate_seconds)
+            || (session->opt->renegotiate_bytes > 0
+                && ks->n_bytes >= session->opt->renegotiate_bytes)
+            || (session->opt->renegotiate_packets
+                && ks->n_packets >= session->opt->renegotiate_packets)
+            || (packet_id_close_to_wrapping(&ks->crypto_options.packet_id.send))))
+    {
+        msg(D_TLS_DEBUG_LOW,
+            "TLS: soft reset sec=%d bytes=" counter_format "/%d pkts=" counter_format "/%d",
+            (int)(ks->established + session->opt->renegotiate_seconds - now),
+            ks->n_bytes, session->opt->renegotiate_bytes,
+            ks->n_packets, session->opt->renegotiate_packets);
+        key_state_soft_reset(session);
+    }
+
+    /* Kill lame duck key transition_window seconds after primary key negotiation */
+    if (lame_duck_must_die(session, wakeup))
+    {
+        key_state_free(ks_lame, true);
+        msg(D_TLS_DEBUG_LOW, "TLS: tls_process: killed expiring key");
+    }
+
+    do
+    {
+        update_time();
+
+        dmsg(D_TLS_DEBUG, "TLS: tls_process: chg=%d ks=%s lame=%s to_link->len=%d wakeup=%d",
+             state_change,
+             state_name(ks->state),
+             state_name(ks_lame->state),
+             to_link->len,
+             *wakeup);
+
+        state_change = false;
+
+        /*
+         * TLS activity is finished once we get to S_ACTIVE,
+         * though we will still process acknowledgements.
+         *
+         * CHANGED with 2.0 -> now we may send tunnel configuration
+         * info over the control channel.
+         */
+
+        /* Initial handshake */
+        if (ks->state == S_INITIAL)
+        {
+            buf = reliable_get_buf_output_sequenced(ks->send_reliable);
+            if (buf)
+            {
+                ks->must_negotiate = now + session->opt->handshake_window;
+                ks->auth_deferred_expire = now + auth_deferred_expire_window(session->opt);
+
+                /* null buffer */
+                reliable_mark_active_outgoing(ks->send_reliable, buf, ks->initial_opcode);
+                INCR_GENERATED;
+
+                ks->state = S_PRE_START;
+                state_change = true;
+                dmsg(D_TLS_DEBUG, "TLS: Initial Handshake, sid=%s",
+                     session_id_print(&session->session_id, &gc));
+
+#ifdef ENABLE_MANAGEMENT
+                if (management && ks->initial_opcode != P_CONTROL_SOFT_RESET_V1)
+                {
+                    management_set_state(management,
+                                         OPENVPN_STATE_WAIT,
+                                         NULL,
+                                         NULL,
+                                         NULL,
+                                         NULL,
+                                         NULL);
+                }
+#endif
+            }
+        }
+
+        /* Are we timed out on receive? */
+        if (now >= ks->must_negotiate)
+        {
+            if (ks->state < S_ACTIVE)
+            {
+                msg(D_TLS_ERRORS,
+                    "TLS Error: TLS key negotiation failed to occur within %d seconds (check your network connectivity)",
+                    session->opt->handshake_window);
+                goto error;
+            }
+            else /* assume that ks->state == S_ACTIVE */
+            {
+                dmsg(D_TLS_DEBUG_MED, "STATE S_NORMAL_OP");
+                ks->state = S_NORMAL_OP;
+                ks->must_negotiate = 0;
+            }
+        }
+
+        /* Wait for Initial Handshake ACK */
+        if (ks->state == S_PRE_START && FULL_SYNC)
+        {
+            ks->state = S_START;
+            state_change = true;
+
+            /*
+             * Attempt CRL reload before TLS negotiation. Won't be performed if
+             * the file was not modified since the last reload
+             */
+            if (session->opt->crl_file
+                && !(session->opt->ssl_flags & SSLF_CRL_VERIFY_DIR))
+            {
+                tls_ctx_reload_crl(&session->opt->ssl_ctx,
+                                   session->opt->crl_file, session->opt->crl_file_inline);
+            }
+
+            /* New connection, remove any old X509 env variables */
+            tls_x509_clear_env(session->opt->es);
+
+            dmsg(D_TLS_DEBUG_MED, "STATE S_START");
+        }
+
+        /* Wait for ACK */
+        if (((ks->state == S_GOT_KEY && !session->opt->server)
+             || (ks->state == S_SENT_KEY && session->opt->server)))
+        {
+            if (FULL_SYNC)
+            {
+                ks->established = now;
+                dmsg(D_TLS_DEBUG_MED, "STATE S_ACTIVE");
+                if (check_debug_level(D_HANDSHAKE))
+                {
+                    print_details(&ks->ks_ssl, "Control Channel:");
+                }
+                state_change = true;
+                ks->state = S_ACTIVE;
+                INCR_SUCCESS;
+
+                /* Set outgoing address for data channel packets */
+                link_socket_set_outgoing_addr(NULL, to_link_socket_info, &ks->remote_addr, session->common_name, session->opt->es);
+
+                /* Flush any payload packets that were buffered before our state transitioned to S_ACTIVE */
+                flush_payload_buffer(ks);
+
+#ifdef MEASURE_TLS_HANDSHAKE_STATS
+                show_tls_performance_stats();
+#endif
+            }
+        }
+
+        /* Reliable buffer to outgoing TCP/UDP (send up to CONTROL_SEND_ACK_MAX ACKs
+         * for previously received packets) */
+        if (!to_link->len && reliable_can_send(ks->send_reliable))
+        {
+            int opcode;
+            struct buffer b;
+
+            buf = reliable_send(ks->send_reliable, &opcode);
+            ASSERT(buf);
+            b = *buf;
+            INCR_SENT;
+
+            write_control_auth(session, ks, &b, to_link_addr, opcode,
+                               CONTROL_SEND_ACK_MAX, true);
+            *to_link = b;
+            active = true;
+            state_change = true;
+            dmsg(D_TLS_DEBUG, "Reliable -> TCP/UDP");
+            break;
+        }
+
+        /* Write incoming ciphertext to TLS object */
+        buf = reliable_get_buf_sequenced(ks->rec_reliable);
+        if (buf)
+        {
+            int status = 0;
+            if (buf->len)
+            {
+                status = key_state_write_ciphertext(&ks->ks_ssl, buf);
+                if (status == -1)
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: Incoming Ciphertext -> TLS object write error");
+                    goto error;
+                }
+            }
+            else
+            {
+                status = 1;
+            }
+            if (status == 1)
+            {
+                reliable_mark_deleted(ks->rec_reliable, buf, true);
+                state_change = true;
+                dmsg(D_TLS_DEBUG, "Incoming Ciphertext -> TLS");
+            }
+        }
+
+        /* Read incoming plaintext from TLS object */
+        buf = &ks->plaintext_read_buf;
+        if (!buf->len)
+        {
+            int status;
+
+            ASSERT(buf_init(buf, 0));
+            status = key_state_read_plaintext(&ks->ks_ssl, buf, TLS_CHANNEL_BUF_SIZE);
+            update_time();
+            if (status == -1)
+            {
+                msg(D_TLS_ERRORS, "TLS Error: TLS object -> incoming plaintext read error");
+                goto error;
+            }
+            if (status == 1)
+            {
+                state_change = true;
+                dmsg(D_TLS_DEBUG, "TLS -> Incoming Plaintext");
+
+                /* More data may be available, wake up again asap to check. */
+                *wakeup = 0;
+            }
+        }
+
+        /* Send Key */
+        buf = &ks->plaintext_write_buf;
+        if (!buf->len && ((ks->state == S_START && !session->opt->server)
+                          || (ks->state == S_GOT_KEY && session->opt->server)))
+        {
+            if (session->opt->key_method == 1)
+            {
+                if (!key_method_1_write(buf, session))
+                {
+                    goto error;
+                }
+            }
+            else if (session->opt->key_method == 2)
+            {
+                if (!key_method_2_write(buf, session))
+                {
+                    goto error;
+                }
+            }
+            else
+            {
+                ASSERT(0);
+            }
+
+            state_change = true;
+            dmsg(D_TLS_DEBUG_MED, "STATE S_SENT_KEY");
+            ks->state = S_SENT_KEY;
+        }
+
+        /* Receive Key */
+        buf = &ks->plaintext_read_buf;
+        if (buf->len
+            && ((ks->state == S_SENT_KEY && !session->opt->server)
+                || (ks->state == S_START && session->opt->server)))
+        {
+            if (session->opt->key_method == 1)
+            {
+                if (!key_method_1_read(buf, session))
+                {
+                    goto error;
+                }
+            }
+            else if (session->opt->key_method == 2)
+            {
+                if (!key_method_2_read(buf, multi, session))
+                {
+                    goto error;
+                }
+            }
+            else
+            {
+                ASSERT(0);
+            }
+
+            state_change = true;
+            dmsg(D_TLS_DEBUG_MED, "STATE S_GOT_KEY");
+            ks->state = S_GOT_KEY;
+        }
+
+        /* Write outgoing plaintext to TLS object */
+        buf = &ks->plaintext_write_buf;
+        if (buf->len)
+        {
+            int status = key_state_write_plaintext(&ks->ks_ssl, buf);
+            if (status == -1)
+            {
+                msg(D_TLS_ERRORS,
+                    "TLS ERROR: Outgoing Plaintext -> TLS object write error");
+                goto error;
+            }
+            if (status == 1)
+            {
+                state_change = true;
+                dmsg(D_TLS_DEBUG, "Outgoing Plaintext -> TLS");
+            }
+        }
+
+        /* Outgoing Ciphertext to reliable buffer */
+        if (ks->state >= S_START)
+        {
+            buf = reliable_get_buf_output_sequenced(ks->send_reliable);
+            if (buf)
+            {
+                int status = key_state_read_ciphertext(&ks->ks_ssl, buf, PAYLOAD_SIZE_DYNAMIC(&multi->opt.frame));
+                if (status == -1)
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: Ciphertext -> reliable TCP/UDP transport read error");
+                    goto error;
+                }
+                if (status == 1)
+                {
+                    reliable_mark_active_outgoing(ks->send_reliable, buf, P_CONTROL_V1);
+                    INCR_GENERATED;
+                    state_change = true;
+                    dmsg(D_TLS_DEBUG, "Outgoing Ciphertext -> Reliable");
+                }
+            }
+        }
+    }
+    while (state_change);
+
+    update_time();
+
+    /* Send 1 or more ACKs (each received control packet gets one ACK) */
+    if (!to_link->len && !reliable_ack_empty(ks->rec_ack))
+    {
+        struct buffer buf = ks->ack_write_buf;
+        ASSERT(buf_init(&buf, FRAME_HEADROOM(&multi->opt.frame)));
+        write_control_auth(session, ks, &buf, to_link_addr, P_ACK_V1,
+                           RELIABLE_ACK_SIZE, false);
+        *to_link = buf;
+        active = true;
+        dmsg(D_TLS_DEBUG, "Dedicated ACK -> TCP/UDP");
+    }
+
+    /* When should we wake up again? */
+    {
+        if (ks->state >= S_INITIAL)
+        {
+            compute_earliest_wakeup(wakeup,
+                                    reliable_send_timeout(ks->send_reliable));
+
+            if (ks->must_negotiate)
+            {
+                compute_earliest_wakeup(wakeup, ks->must_negotiate - now);
+            }
+        }
+
+        if (ks->established && session->opt->renegotiate_seconds)
+        {
+            compute_earliest_wakeup(wakeup,
+                                    ks->established + session->opt->renegotiate_seconds - now);
+        }
+
+        /* prevent event-loop spinning by setting minimum wakeup of 1 second */
+        if (*wakeup <= 0)
+        {
+            *wakeup = 1;
+
+            /* if we had something to send to remote, but to_link was busy,
+             * let caller know we need to be called again soon */
+            active = true;
+        }
+
+        dmsg(D_TLS_DEBUG, "TLS: tls_process: timeout set to %d", *wakeup);
+
+        gc_free(&gc);
+        return active;
+    }
+
+error:
+    tls_clear_error();
+    ks->state = S_ERROR;
+    msg(D_TLS_ERRORS, "TLS Error: TLS handshake failed");
+    INCR_ERROR;
+    gc_free(&gc);
+    return false;
+}
+
+/*
+ * Called by the top-level event loop.
+ *
+ * Basically decides if we should call tls_process for
+ * the active or untrusted sessions.
+ */
+
+int
+tls_multi_process(struct tls_multi *multi,
+                  struct buffer *to_link,
+                  struct link_socket_actual **to_link_addr,
+                  struct link_socket_info *to_link_socket_info,
+                  interval_t *wakeup)
+{
+    struct gc_arena gc = gc_new();
+    int i;
+    int active = TLSMP_INACTIVE;
+    bool error = false;
+    int tas;
+
+    perf_push(PERF_TLS_MULTI_PROCESS);
+
+    tls_clear_error();
+
+    /*
+     * Process each session object having state of S_INITIAL or greater,
+     * and which has a defined remote IP addr.
+     */
+
+    for (i = 0; i < TM_SIZE; ++i)
+    {
+        struct tls_session *session = &multi->session[i];
+        struct key_state *ks = &session->key[KS_PRIMARY];
+        struct key_state *ks_lame = &session->key[KS_LAME_DUCK];
+
+        /* set initial remote address */
+        if (i == TM_ACTIVE && ks->state == S_INITIAL
+            && link_socket_actual_defined(&to_link_socket_info->lsa->actual))
+        {
+            ks->remote_addr = to_link_socket_info->lsa->actual;
+        }
+
+        dmsg(D_TLS_DEBUG,
+             "TLS: tls_multi_process: i=%d state=%s, mysid=%s, stored-sid=%s, stored-ip=%s",
+             i,
+             state_name(ks->state),
+             session_id_print(&session->session_id, &gc),
+             session_id_print(&ks->session_id_remote, &gc),
+             print_link_socket_actual(&ks->remote_addr, &gc));
+
+        if (ks->state >= S_INITIAL && link_socket_actual_defined(&ks->remote_addr))
+        {
+            struct link_socket_actual *tla = NULL;
+
+            update_time();
+
+            if (tls_process(multi, session, to_link, &tla,
+                            to_link_socket_info, wakeup))
+            {
+                active = TLSMP_ACTIVE;
+            }
+
+            /*
+             * If tls_process produced an outgoing packet,
+             * return the link_socket_actual object (which
+             * contains the outgoing address).
+             */
+            if (tla)
+            {
+                multi->to_link_addr = *tla;
+                *to_link_addr = &multi->to_link_addr;
+            }
+
+            /*
+             * If tls_process hits an error:
+             * (1) If the session has an unexpired lame duck key, preserve it.
+             * (2) Reinitialize the session.
+             * (3) Increment soft error count
+             */
+            if (ks->state == S_ERROR)
+            {
+                ++multi->n_soft_errors;
+
+                if (i == TM_ACTIVE)
+                {
+                    error = true;
+                }
+
+                if (i == TM_ACTIVE
+                    && ks_lame->state >= S_ACTIVE
+                    && !multi->opt.single_session)
+                {
+                    move_session(multi, TM_LAME_DUCK, TM_ACTIVE, true);
+                }
+                else
+                {
+                    reset_session(multi, session);
+                }
+            }
+        }
+    }
+
+    update_time();
+
+    tas = tls_authentication_status(multi, TLS_MULTI_AUTH_STATUS_INTERVAL);
+
+    /*
+     * If lame duck session expires, kill it.
+     */
+    if (lame_duck_must_die(&multi->session[TM_LAME_DUCK], wakeup))
+    {
+        tls_session_free(&multi->session[TM_LAME_DUCK], true);
+        msg(D_TLS_DEBUG_LOW, "TLS: tls_multi_process: killed expiring key");
+    }
+
+    /*
+     * If untrusted session achieves TLS authentication,
+     * move it to active session, usurping any prior session.
+     *
+     * A semi-trusted session is one in which the certificate authentication
+     * succeeded (if cert verification is enabled) but the username/password
+     * verification failed.  A semi-trusted session can forward data on the
+     * TLS control channel but not on the tunnel channel.
+     */
+    if (DECRYPT_KEY_ENABLED(multi, &multi->session[TM_UNTRUSTED].key[KS_PRIMARY]))
+    {
+        move_session(multi, TM_ACTIVE, TM_UNTRUSTED, true);
+        msg(D_TLS_DEBUG_LOW, "TLS: tls_multi_process: untrusted session promoted to %strusted",
+            tas == TLS_AUTHENTICATION_SUCCEEDED ? "" : "semi-");
+    }
+
+    /*
+     * A hard error means that TM_ACTIVE hit an S_ERROR state and that no
+     * other key state objects are S_ACTIVE or higher.
+     */
+    if (error)
+    {
+        for (i = 0; i < (int) SIZE(multi->key_scan); ++i)
+        {
+            if (multi->key_scan[i]->state >= S_ACTIVE)
+            {
+                goto nohard;
+            }
+        }
+        ++multi->n_hard_errors;
+    }
+nohard:
+
+#ifdef ENABLE_DEBUG
+    /* DEBUGGING -- flood peer with repeating connection attempts */
+    {
+        const int throw_level = GREMLIN_CONNECTION_FLOOD_LEVEL(multi->opt.gremlin);
+        if (throw_level)
+        {
+            for (i = 0; i < (int) SIZE(multi->key_scan); ++i)
+            {
+                if (multi->key_scan[i]->state >= throw_level)
+                {
+                    ++multi->n_hard_errors;
+                    ++multi->n_soft_errors;
+                }
+            }
+        }
+    }
+#endif
+
+    perf_pop();
+    gc_free(&gc);
+
+    return (tas == TLS_AUTHENTICATION_FAILED) ? TLSMP_KILL : active;
+}
+
+/*
+ * Pre and post-process the encryption & decryption buffers in order
+ * to implement a multiplexed TLS channel over the TCP/UDP port.
+ */
+
+/*
+ *
+ * When we are in TLS mode, this is the first routine which sees
+ * an incoming packet.
+ *
+ * If it's a data packet, we set opt so that our caller can
+ * decrypt it.  We also give our caller the appropriate decryption key.
+ *
+ * If it's a control packet, we authenticate it and process it,
+ * possibly creating a new tls_session if it represents the
+ * first packet of a new session.  For control packets, we will
+ * also zero the size of *buf so that our caller ignores the
+ * packet on our return.
+ *
+ * Note that openvpn only allows one active session at a time,
+ * so a new session (once authenticated) will always usurp
+ * an old session.
+ *
+ * Return true if input was an authenticated control channel
+ * packet.
+ *
+ * If we are running in TLS thread mode, all public routines
+ * below this point must be called with the L_TLS lock held.
+ */
+
+bool
+tls_pre_decrypt(struct tls_multi *multi,
+                const struct link_socket_actual *from,
+                struct buffer *buf,
+                struct crypto_options **opt,
+                bool floated,
+                const uint8_t **ad_start)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+    if (buf->len > 0)
+    {
+        int i;
+        int op;
+        int key_id;
+
+        /* get opcode and key ID */
+        {
+            uint8_t c = *BPTR(buf);
+            op = c >> P_OPCODE_SHIFT;
+            key_id = c & P_KEY_ID_MASK;
+        }
+
+        if ((op == P_DATA_V1) || (op == P_DATA_V2))
+        {
+            /* data channel packet */
+            for (i = 0; i < KEY_SCAN_SIZE; ++i)
+            {
+                struct key_state *ks = multi->key_scan[i];
+
+                /*
+                 * This is the basic test of TLS state compatibility between a local OpenVPN
+                 * instance and its remote peer.
+                 *
+                 * If the test fails, it tells us that we are getting a packet from a source
+                 * which claims reference to a prior negotiated TLS session, but the local
+                 * OpenVPN instance has no memory of such a negotiation.
+                 *
+                 * It almost always occurs on UDP sessions when the passive side of the
+                 * connection is restarted without the active side restarting as well (the
+                 * passive side is the server which only listens for the connections, the
+                 * active side is the client which initiates connections).
+                 */
+                if (DECRYPT_KEY_ENABLED(multi, ks)
+                    && key_id == ks->key_id
+                    && ks->authenticated
+#ifdef ENABLE_DEF_AUTH
+                    && !ks->auth_deferred
+#endif
+                    && (floated || link_socket_actual_match(from, &ks->remote_addr)))
+                {
+                    if (!ks->crypto_options.key_ctx_bi.initialized)
+                    {
+                        msg(D_MULTI_DROPPED,
+                            "Key %s [%d] not initialized (yet), dropping packet.",
+                            print_link_socket_actual(from, &gc), key_id);
+                        goto error_lite;
+                    }
+
+                    /* return appropriate data channel decrypt key in opt */
+                    *opt = &ks->crypto_options;
+                    if (op == P_DATA_V2)
+                    {
+                        *ad_start = BPTR(buf);
+                    }
+                    ASSERT(buf_advance(buf, 1));
+                    if (op == P_DATA_V1)
+                    {
+                        *ad_start = BPTR(buf);
+                    }
+                    else if (op == P_DATA_V2)
+                    {
+                        if (buf->len < 4)
+                        {
+                            msg(D_TLS_ERRORS, "Protocol error: received P_DATA_V2 from %s but length is < 4",
+                                print_link_socket_actual(from, &gc));
+                            goto error;
+                        }
+                        ASSERT(buf_advance(buf, 3));
+                    }
+
+                    ++ks->n_packets;
+                    ks->n_bytes += buf->len;
+                    dmsg(D_TLS_KEYSELECT,
+                         "TLS: tls_pre_decrypt, key_id=%d, IP=%s",
+                         key_id, print_link_socket_actual(from, &gc));
+                    gc_free(&gc);
+                    return ret;
+                }
+            }
+
+            msg(D_TLS_ERRORS,
+                "TLS Error: local/remote TLS keys are out of sync: %s [%d]",
+                print_link_socket_actual(from, &gc), key_id);
+            goto error_lite;
+        }
+        else                      /* control channel packet */
+        {
+            bool do_burst = false;
+            bool new_link = false;
+            struct session_id sid; /* remote session ID */
+
+            /* verify legal opcode */
+            if (op < P_FIRST_OPCODE || op > P_LAST_OPCODE)
+            {
+                msg(D_TLS_ERRORS,
+                    "TLS Error: unknown opcode received from %s op=%d",
+                    print_link_socket_actual(from, &gc), op);
+                goto error;
+            }
+
+            /* hard reset ? */
+            if (is_hard_reset(op, 0))
+            {
+                /* verify client -> server or server -> client connection */
+                if (((op == P_CONTROL_HARD_RESET_CLIENT_V1
+                      || op == P_CONTROL_HARD_RESET_CLIENT_V2) && !multi->opt.server)
+                    || ((op == P_CONTROL_HARD_RESET_SERVER_V1
+                         || op == P_CONTROL_HARD_RESET_SERVER_V2) && multi->opt.server))
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: client->client or server->server connection attempted from %s",
+                        print_link_socket_actual(from, &gc));
+                    goto error;
+                }
+            }
+
+            /*
+             * Authenticate Packet
+             */
+            dmsg(D_TLS_DEBUG, "TLS: control channel, op=%s, IP=%s",
+                 packet_opcode_name(op), print_link_socket_actual(from, &gc));
+
+            /* get remote session-id */
+            {
+                struct buffer tmp = *buf;
+                buf_advance(&tmp, 1);
+                if (!session_id_read(&sid, &tmp) || !session_id_defined(&sid))
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: session-id not found in packet from %s",
+                        print_link_socket_actual(from, &gc));
+                    goto error;
+                }
+            }
+
+            /* use session ID to match up packet with appropriate tls_session object */
+            for (i = 0; i < TM_SIZE; ++i)
+            {
+                struct tls_session *session = &multi->session[i];
+                struct key_state *ks = &session->key[KS_PRIMARY];
+
+                dmsg(D_TLS_DEBUG,
+                     "TLS: initial packet test, i=%d state=%s, mysid=%s, rec-sid=%s, rec-ip=%s, stored-sid=%s, stored-ip=%s",
+                     i,
+                     state_name(ks->state),
+                     session_id_print(&session->session_id, &gc),
+                     session_id_print(&sid, &gc),
+                     print_link_socket_actual(from, &gc),
+                     session_id_print(&ks->session_id_remote, &gc),
+                     print_link_socket_actual(&ks->remote_addr, &gc));
+
+                if (session_id_equal(&ks->session_id_remote, &sid))
+                /* found a match */
+                {
+                    if (i == TM_LAME_DUCK)
+                    {
+                        msg(D_TLS_ERRORS,
+                            "TLS ERROR: received control packet with stale session-id=%s",
+                            session_id_print(&sid, &gc));
+                        goto error;
+                    }
+                    dmsg(D_TLS_DEBUG,
+                         "TLS: found match, session[%d], sid=%s",
+                         i, session_id_print(&sid, &gc));
+                    break;
+                }
+            }
+
+            /*
+             * Initial packet received.
+             */
+
+            if (i == TM_SIZE && is_hard_reset(op, 0))
+            {
+                struct tls_session *session = &multi->session[TM_ACTIVE];
+                struct key_state *ks = &session->key[KS_PRIMARY];
+
+                if (!is_hard_reset(op, multi->opt.key_method))
+                {
+                    msg(D_TLS_ERRORS, "TLS ERROR: initial packet local/remote key_method mismatch, local key_method=%d, op=%s",
+                        multi->opt.key_method,
+                        packet_opcode_name(op));
+                    goto error;
+                }
+
+                /*
+                 * If we have no session currently in progress, the initial packet will
+                 * open a new session in TM_ACTIVE rather than TM_UNTRUSTED.
+                 */
+                if (!session_id_defined(&ks->session_id_remote))
+                {
+                    if (multi->opt.single_session && multi->n_sessions)
+                    {
+                        msg(D_TLS_ERRORS,
+                            "TLS Error: Cannot accept new session request from %s due to session context expire or --single-session [1]",
+                            print_link_socket_actual(from, &gc));
+                        goto error;
+                    }
+
+#ifdef ENABLE_MANAGEMENT
+                    if (management)
+                    {
+                        management_set_state(management,
+                                             OPENVPN_STATE_AUTH,
+                                             NULL,
+                                             NULL,
+                                             NULL,
+                                             NULL,
+                                             NULL);
+                    }
+#endif
+
+                    msg(D_TLS_DEBUG_LOW,
+                        "TLS: Initial packet from %s, sid=%s",
+                        print_link_socket_actual(from, &gc),
+                        session_id_print(&sid, &gc));
+
+                    do_burst = true;
+                    new_link = true;
+                    i = TM_ACTIVE;
+                    session->untrusted_addr = *from;
+                }
+            }
+
+            if (i == TM_SIZE && is_hard_reset(op, 0))
+            {
+                /*
+                 * No match with existing sessions,
+                 * probably a new session.
+                 */
+                struct tls_session *session = &multi->session[TM_UNTRUSTED];
+
+                /*
+                 * If --single-session, don't allow any hard-reset connection request
+                 * unless it the the first packet of the session.
+                 */
+                if (multi->opt.single_session)
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: Cannot accept new session request from %s due to session context expire or --single-session [2]",
+                        print_link_socket_actual(from, &gc));
+                    goto error;
+                }
+
+                if (!is_hard_reset(op, multi->opt.key_method))
+                {
+                    msg(D_TLS_ERRORS, "TLS ERROR: new session local/remote key_method mismatch, local key_method=%d, op=%s",
+                        multi->opt.key_method,
+                        packet_opcode_name(op));
+                    goto error;
+                }
+
+                if (!read_control_auth(buf, &session->tls_wrap, from))
+                {
+                    goto error;
+                }
+
+                /*
+                 * New session-initiating control packet is authenticated at this point,
+                 * assuming that the --tls-auth command line option was used.
+                 *
+                 * Without --tls-auth, we leave authentication entirely up to TLS.
+                 */
+                msg(D_TLS_DEBUG_LOW,
+                    "TLS: new session incoming connection from %s",
+                    print_link_socket_actual(from, &gc));
+
+                new_link = true;
+                i = TM_UNTRUSTED;
+                session->untrusted_addr = *from;
+            }
+            else
+            {
+                struct tls_session *session = &multi->session[i];
+                struct key_state *ks = &session->key[KS_PRIMARY];
+
+                /*
+                 * Packet must belong to an existing session.
+                 */
+                if (i != TM_ACTIVE && i != TM_UNTRUSTED)
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: Unroutable control packet received from %s (si=%d op=%s)",
+                        print_link_socket_actual(from, &gc),
+                        i,
+                        packet_opcode_name(op));
+                    goto error;
+                }
+
+                /*
+                 * Verify remote IP address
+                 */
+                if (!new_link && !link_socket_actual_match(&ks->remote_addr, from))
+                {
+                    msg(D_TLS_ERRORS, "TLS Error: Received control packet from unexpected IP addr: %s",
+                        print_link_socket_actual(from, &gc));
+                    goto error;
+                }
+
+                /*
+                 * Remote is requesting a key renegotiation
+                 */
+                if (op == P_CONTROL_SOFT_RESET_V1
+                    && DECRYPT_KEY_ENABLED(multi, ks))
+                {
+                    if (!read_control_auth(buf, &session->tls_wrap, from))
+                    {
+                        goto error;
+                    }
+
+                    key_state_soft_reset(session);
+
+                    dmsg(D_TLS_DEBUG,
+                         "TLS: received P_CONTROL_SOFT_RESET_V1 s=%d sid=%s",
+                         i, session_id_print(&sid, &gc));
+                }
+                else
+                {
+                    /*
+                     * Remote responding to our key renegotiation request?
+                     */
+                    if (op == P_CONTROL_SOFT_RESET_V1)
+                    {
+                        do_burst = true;
+                    }
+
+                    if (!read_control_auth(buf, &session->tls_wrap, from))
+                    {
+                        goto error;
+                    }
+
+                    dmsg(D_TLS_DEBUG,
+                         "TLS: received control channel packet s#=%d sid=%s",
+                         i, session_id_print(&sid, &gc));
+                }
+            }
+
+            /*
+             * We have an authenticated control channel packet (if --tls-auth was set).
+             * Now pass to our reliability layer which deals with
+             * packet acknowledgements, retransmits, sequencing, etc.
+             */
+            {
+                struct tls_session *session = &multi->session[i];
+                struct key_state *ks = &session->key[KS_PRIMARY];
+
+                /* Make sure we were initialized and that we're not in an error state */
+                ASSERT(ks->state != S_UNDEF);
+                ASSERT(ks->state != S_ERROR);
+                ASSERT(session_id_defined(&session->session_id));
+
+                /* Let our caller know we processed a control channel packet */
+                ret = true;
+
+                /*
+                 * Set our remote address and remote session_id
+                 */
+                if (new_link)
+                {
+                    ks->session_id_remote = sid;
+                    ks->remote_addr = *from;
+                    ++multi->n_sessions;
+                }
+                else if (!link_socket_actual_match(&ks->remote_addr, from))
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS Error: Existing session control channel packet from unknown IP address: %s",
+                        print_link_socket_actual(from, &gc));
+                    goto error;
+                }
+
+                /*
+                 * Should we do a retransmit of all unacknowledged packets in
+                 * the send buffer?  This improves the start-up efficiency of the
+                 * initial key negotiation after the 2nd peer comes online.
+                 */
+                if (do_burst && !session->burst)
+                {
+                    reliable_schedule_now(ks->send_reliable);
+                    session->burst = true;
+                }
+
+                /* Check key_id */
+                if (ks->key_id != key_id)
+                {
+                    msg(D_TLS_ERRORS,
+                        "TLS ERROR: local/remote key IDs out of sync (%d/%d) ID: %s",
+                        ks->key_id, key_id, print_key_id(multi, &gc));
+                    goto error;
+                }
+
+                /*
+                 * Process incoming ACKs for packets we can now
+                 * delete from reliable send buffer
+                 */
+                {
+                    /* buffers all packet IDs to delete from send_reliable */
+                    struct reliable_ack send_ack;
+
+                    send_ack.len = 0;
+                    if (!reliable_ack_read(&send_ack, buf, &session->session_id))
+                    {
+                        msg(D_TLS_ERRORS,
+                            "TLS Error: reading acknowledgement record from packet");
+                        goto error;
+                    }
+                    reliable_send_purge(ks->send_reliable, &send_ack);
+                }
+
+                if (op != P_ACK_V1 && reliable_can_get(ks->rec_reliable))
+                {
+                    packet_id_type id;
+
+                    /* Extract the packet ID from the packet */
+                    if (reliable_ack_read_packet_id(buf, &id))
+                    {
+                        /* Avoid deadlock by rejecting packet that would de-sequentialize receive buffer */
+                        if (reliable_wont_break_sequentiality(ks->rec_reliable, id))
+                        {
+                            if (reliable_not_replay(ks->rec_reliable, id))
+                            {
+                                /* Save incoming ciphertext packet to reliable buffer */
+                                struct buffer *in = reliable_get_buf(ks->rec_reliable);
+                                ASSERT(in);
+                                if(!buf_copy(in, buf))
+                                {
+                                    msg(D_MULTI_DROPPED,
+                                        "Incoming control channel packet too big, dropping.");
+                                    goto error;
+                                }
+                                reliable_mark_active_incoming(ks->rec_reliable, in, id, op);
+                            }
+
+                            /* Process outgoing acknowledgment for packet just received, even if it's a replay */
+                            reliable_ack_acknowledge_packet_id(ks->rec_ack, id);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+done:
+    buf->len = 0;
+    *opt = NULL;
+    gc_free(&gc);
+    return ret;
+
+error:
+    ++multi->n_soft_errors;
+error_lite:
+    tls_clear_error();
+    goto done;
+}
+
+/*
+ * This function is similar to tls_pre_decrypt, except it is called
+ * when we are in server mode and receive an initial incoming
+ * packet.  Note that we don't modify
+ * any state in our parameter objects.  The purpose is solely to
+ * determine whether we should generate a client instance
+ * object, in which case true is returned.
+ *
+ * This function is essentially the first-line HMAC firewall
+ * on the UDP port listener in --mode server mode.
+ */
+bool
+tls_pre_decrypt_lite(const struct tls_auth_standalone *tas,
+                     const struct link_socket_actual *from,
+                     const struct buffer *buf)
+
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+
+    if (buf->len > 0)
+    {
+        int op;
+        int key_id;
+
+        /* get opcode and key ID */
+        {
+            uint8_t c = *BPTR(buf);
+            op = c >> P_OPCODE_SHIFT;
+            key_id = c & P_KEY_ID_MASK;
+        }
+
+        /* this packet is from an as-yet untrusted source, so
+         * scrutinize carefully */
+
+        if (op != P_CONTROL_HARD_RESET_CLIENT_V2)
+        {
+            /*
+             * This can occur due to bogus data or DoS packets.
+             */
+            dmsg(D_TLS_STATE_ERRORS,
+                 "TLS State Error: No TLS state for client %s, opcode=%d",
+                 print_link_socket_actual(from, &gc),
+                 op);
+            goto error;
+        }
+
+        if (key_id != 0)
+        {
+            dmsg(D_TLS_STATE_ERRORS,
+                 "TLS State Error: Unknown key ID (%d) received from %s -- 0 was expected",
+                 key_id,
+                 print_link_socket_actual(from, &gc));
+            goto error;
+        }
+
+        if (buf->len > EXPANDED_SIZE_DYNAMIC(&tas->frame))
+        {
+            dmsg(D_TLS_STATE_ERRORS,
+                 "TLS State Error: Large packet (size %d) received from %s -- a packet no larger than %d bytes was expected",
+                 buf->len,
+                 print_link_socket_actual(from, &gc),
+                 EXPANDED_SIZE_DYNAMIC(&tas->frame));
+            goto error;
+        }
+
+        {
+            struct buffer newbuf = clone_buf(buf);
+            struct tls_wrap_ctx tls_wrap_tmp = tas->tls_wrap;
+            bool status;
+
+            /* HMAC test, if --tls-auth was specified */
+            status = read_control_auth(&newbuf, &tls_wrap_tmp, from);
+            free_buf(&newbuf);
+            if (!status)
+            {
+                goto error;
+            }
+
+            /*
+             * At this point, if --tls-auth is being used, we know that
+             * the packet has passed the HMAC test, but we don't know if
+             * it is a replay yet.  We will attempt to defeat replays
+             * by not advancing to the S_START state until we
+             * receive an ACK from our first reply to the client
+             * that includes an HMAC of our randomly generated 64 bit
+             * session ID.
+             *
+             * On the other hand if --tls-auth is not being used, we
+             * will proceed to begin the TLS authentication
+             * handshake with only cursory integrity checks having
+             * been performed, since we will be leaving the task
+             * of authentication solely up to TLS.
+             */
+
+            ret = true;
+        }
+    }
+    gc_free(&gc);
+    return ret;
+
+error:
+    tls_clear_error();
+    gc_free(&gc);
+    return ret;
+}
+
+/* Choose the key with which to encrypt a data packet */
+void
+tls_pre_encrypt(struct tls_multi *multi,
+                struct buffer *buf, struct crypto_options **opt)
+{
+    multi->save_ks = NULL;
+    if (buf->len > 0)
+    {
+        int i;
+        struct key_state *ks_select = NULL;
+        for (i = 0; i < KEY_SCAN_SIZE; ++i)
+        {
+            struct key_state *ks = multi->key_scan[i];
+            if (ks->state >= S_ACTIVE
+                && ks->authenticated
+                && ks->crypto_options.key_ctx_bi.initialized
+#ifdef ENABLE_DEF_AUTH
+                && !ks->auth_deferred
+#endif
+                )
+            {
+                if (!ks_select)
+                {
+                    ks_select = ks;
+                }
+                if (now >= ks->auth_deferred_expire)
+                {
+                    ks_select = ks;
+                    break;
+                }
+            }
+        }
+
+        if (ks_select)
+        {
+            *opt = &ks_select->crypto_options;
+            multi->save_ks = ks_select;
+            dmsg(D_TLS_KEYSELECT, "TLS: tls_pre_encrypt: key_id=%d", ks_select->key_id);
+            return;
+        }
+        else
+        {
+            struct gc_arena gc = gc_new();
+            dmsg(D_TLS_KEYSELECT, "TLS Warning: no data channel send key available: %s",
+                 print_key_id(multi, &gc));
+            gc_free(&gc);
+        }
+    }
+
+    buf->len = 0;
+    *opt = NULL;
+}
+
+void
+tls_prepend_opcode_v1(const struct tls_multi *multi, struct buffer *buf)
+{
+    struct key_state *ks = multi->save_ks;
+    uint8_t op;
+
+    msg(D_TLS_DEBUG, __func__);
+
+    ASSERT(ks);
+
+    op = (P_DATA_V1 << P_OPCODE_SHIFT) | ks->key_id;
+    ASSERT(buf_write_prepend(buf, &op, 1));
+}
+
+void
+tls_prepend_opcode_v2(const struct tls_multi *multi, struct buffer *buf)
+{
+    struct key_state *ks = multi->save_ks;
+    uint32_t peer;
+
+    msg(D_TLS_DEBUG, __func__);
+
+    ASSERT(ks);
+
+    peer = htonl(((P_DATA_V2 << P_OPCODE_SHIFT) | ks->key_id) << 24
+                 | (multi->peer_id & 0xFFFFFF));
+    ASSERT(buf_write_prepend(buf, &peer, 4));
+}
+
+void
+tls_post_encrypt(struct tls_multi *multi, struct buffer *buf)
+{
+    struct key_state *ks = multi->save_ks;
+    multi->save_ks = NULL;
+
+    if (buf->len > 0)
+    {
+        ASSERT(ks);
+
+        ++ks->n_packets;
+        ks->n_bytes += buf->len;
+    }
+}
+
+/*
+ * Send a payload over the TLS control channel.
+ * Called externally.
+ */
+
+bool
+tls_send_payload(struct tls_multi *multi,
+                 const uint8_t *data,
+                 int size)
+{
+    struct tls_session *session;
+    struct key_state *ks;
+    bool ret = false;
+
+    tls_clear_error();
+
+    ASSERT(multi);
+
+    session = &multi->session[TM_ACTIVE];
+    ks = &session->key[KS_PRIMARY];
+
+    if (ks->state >= S_ACTIVE)
+    {
+        if (key_state_write_plaintext_const(&ks->ks_ssl, data, size) == 1)
+        {
+            ret = true;
+        }
+    }
+    else
+    {
+        if (!ks->paybuf)
+        {
+            ks->paybuf = buffer_list_new(0);
+        }
+        buffer_list_push_data(ks->paybuf, data, (size_t)size);
+        ret = true;
+    }
+
+
+    tls_clear_error();
+
+    return ret;
+}
+
+bool
+tls_rec_payload(struct tls_multi *multi,
+                struct buffer *buf)
+{
+    struct tls_session *session;
+    struct key_state *ks;
+    bool ret = false;
+
+    tls_clear_error();
+
+    ASSERT(multi);
+
+    session = &multi->session[TM_ACTIVE];
+    ks = &session->key[KS_PRIMARY];
+
+    if (ks->state >= S_ACTIVE && BLEN(&ks->plaintext_read_buf))
+    {
+        if (buf_copy(buf, &ks->plaintext_read_buf))
+        {
+            ret = true;
+        }
+        ks->plaintext_read_buf.len = 0;
+    }
+
+    tls_clear_error();
+
+    return ret;
+}
+
+void
+tls_update_remote_addr(struct tls_multi *multi, const struct link_socket_actual *addr)
+{
+    struct gc_arena gc = gc_new();
+    int i, j;
+
+    for (i = 0; i < TM_SIZE; ++i)
+    {
+        struct tls_session *session = &multi->session[i];
+
+        for (j = 0; j < KS_SIZE; ++j)
+        {
+            struct key_state *ks = &session->key[j];
+
+            if (!link_socket_actual_defined(&ks->remote_addr)
+                || link_socket_actual_match(addr, &ks->remote_addr))
+            {
+                continue;
+            }
+
+            dmsg(D_TLS_KEYSELECT, "TLS: tls_update_remote_addr from IP=%s to IP=%s",
+                 print_link_socket_actual(&ks->remote_addr, &gc),
+                 print_link_socket_actual(addr, &gc));
+
+            ks->remote_addr = *addr;
+        }
+    }
+    gc_free(&gc);
+}
+
+int
+tls_peer_info_ncp_ver(const char *peer_info)
+{
+    const char *ncpstr = peer_info ? strstr(peer_info, "IV_NCP=") : NULL;
+    if (ncpstr)
+    {
+        int ncp = 0;
+        int r = sscanf(ncpstr, "IV_NCP=%d", &ncp);
+        if (r == 1)
+        {
+            return ncp;
+        }
+    }
+    return 0;
+}
+
+bool
+tls_check_ncp_cipher_list(const char *list)
+{
+    bool unsupported_cipher_found = false;
+
+    ASSERT(list);
+
+    char *const tmp_ciphers = string_alloc(list, NULL);
+    const char *token = strtok(tmp_ciphers, ":");
+    while (token)
+    {
+        if (!cipher_kt_get(translate_cipher_name_from_openvpn(token)))
+        {
+            msg(M_WARN, "Unsupported cipher in --ncp-ciphers: %s", token);
+            unsupported_cipher_found = true;
+        }
+        token = strtok(NULL, ":");
+    }
+    free(tmp_ciphers);
+
+    return 0 < strlen(list) && !unsupported_cipher_found;
+}
+
+void
+show_available_tls_ciphers(const char *cipher_list,
+                           const char *cipher_list_tls13,
+                           const char *tls_cert_profile)
+{
+    printf("Available TLS Ciphers, listed in order of preference:\n");
+
+#if (ENABLE_CRYPTO_OPENSSL && OPENSSL_VERSION_NUMBER >= 0x1010100fL)
+    printf("\nFor TLS 1.3 and newer (--tls-ciphersuites):\n\n");
+    show_available_tls_ciphers_list(cipher_list_tls13, tls_cert_profile, true);
+#else
+    (void) cipher_list_tls13;  /* Avoid unused warning */
+#endif
+
+    printf("\nFor TLS 1.2 and older (--tls-cipher):\n\n");
+    show_available_tls_ciphers_list(cipher_list, tls_cert_profile, false);
+
+    printf("\n"
+    "Be aware that that whether a cipher suite in this list can actually work\n"
+    "depends on the specific setup of both peers. See the man page entries of\n"
+    "--tls-cipher and --show-tls for more details.\n\n"
+    );
+}
+
+/*
+ * Dump a human-readable rendition of an openvpn packet
+ * into a garbage collectable string which is returned.
+ */
+const char *
+protocol_dump(struct buffer *buffer, unsigned int flags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    struct buffer buf = *buffer;
+
+    uint8_t c;
+    int op;
+    int key_id;
+
+    int tls_auth_hmac_size = (flags & PD_TLS_AUTH_HMAC_SIZE_MASK);
+
+    if (buf.len <= 0)
+    {
+        buf_printf(&out, "DATA UNDEF len=%d", buf.len);
+        goto done;
+    }
+
+    if (!(flags & PD_TLS))
+    {
+        goto print_data;
+    }
+
+    /*
+     * Initial byte (opcode)
+     */
+    if (!buf_read(&buf, &c, sizeof(c)))
+    {
+        goto done;
+    }
+    op = (c >> P_OPCODE_SHIFT);
+    key_id = c & P_KEY_ID_MASK;
+    buf_printf(&out, "%s kid=%d", packet_opcode_name(op), key_id);
+
+    if ((op == P_DATA_V1) || (op == P_DATA_V2))
+    {
+        goto print_data;
+    }
+
+    /*
+     * Session ID
+     */
+    {
+        struct session_id sid;
+
+        if (!session_id_read(&sid, &buf))
+        {
+            goto done;
+        }
+        if (flags & PD_VERBOSE)
+        {
+            buf_printf(&out, " sid=%s", session_id_print(&sid, gc));
+        }
+    }
+
+    /*
+     * tls-auth hmac + packet_id
+     */
+    if (tls_auth_hmac_size)
+    {
+        struct packet_id_net pin;
+        uint8_t tls_auth_hmac[MAX_HMAC_KEY_LENGTH];
+
+        ASSERT(tls_auth_hmac_size <= MAX_HMAC_KEY_LENGTH);
+
+        if (!buf_read(&buf, tls_auth_hmac, tls_auth_hmac_size))
+        {
+            goto done;
+        }
+        if (flags & PD_VERBOSE)
+        {
+            buf_printf(&out, " tls_hmac=%s", format_hex(tls_auth_hmac, tls_auth_hmac_size, 0, gc));
+        }
+
+        if (!packet_id_read(&pin, &buf, true))
+        {
+            goto done;
+        }
+        buf_printf(&out, " pid=%s", packet_id_net_print(&pin, (flags & PD_VERBOSE), gc));
+    }
+
+    /*
+     * ACK list
+     */
+    buf_printf(&out, " %s", reliable_ack_print(&buf, (flags & PD_VERBOSE), gc));
+
+    if (op == P_ACK_V1)
+    {
+        goto done;
+    }
+
+    /*
+     * Packet ID
+     */
+    {
+        packet_id_type l;
+        if (!buf_read(&buf, &l, sizeof(l)))
+        {
+            goto done;
+        }
+        l = ntohpid(l);
+        buf_printf(&out, " pid=" packet_id_format, (packet_id_print_type)l);
+    }
+
+print_data:
+    if (flags & PD_SHOW_DATA)
+    {
+        buf_printf(&out, " DATA %s", format_hex(BPTR(&buf), BLEN(&buf), 80, gc));
+    }
+    else
+    {
+        buf_printf(&out, " DATA len=%d", buf.len);
+    }
+
+done:
+    return BSTR(&out);
+}
+
+void
+delayed_auth_pass_purge(void)
+{
+    auth_user_pass.wait_for_push = false;
+    purge_user_pass(&auth_user_pass, false);
+}
+
+#else  /* if defined(ENABLE_CRYPTO) */
+static void
+dummy(void)
+{
+}
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/ssl.h b/src/openvpn/ssl.h
new file mode 100644
index 0000000..3266f38
--- /dev/null
+++ b/src/openvpn/ssl.h
@@ -0,0 +1,624 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel SSL/Data channel negotiation module
+ */
+
+#ifndef OPENVPN_SSL_H
+#define OPENVPN_SSL_H
+
+#if defined(ENABLE_CRYPTO)
+
+#include "basic.h"
+#include "common.h"
+#include "crypto.h"
+#include "packet_id.h"
+#include "session_id.h"
+#include "reliable.h"
+#include "socket.h"
+#include "mtu.h"
+#include "options.h"
+#include "plugin.h"
+
+#include "ssl_common.h"
+#include "ssl_backend.h"
+
+/* Used in the TLS PRF function */
+#define KEY_EXPANSION_ID "OpenVPN"
+
+/* packet opcode (high 5 bits) and key-id (low 3 bits) are combined in one byte */
+#define P_KEY_ID_MASK                  0x07
+#define P_OPCODE_SHIFT                 3
+
+/* packet opcodes -- the V1 is intended to allow protocol changes in the future */
+#define P_CONTROL_HARD_RESET_CLIENT_V1 1     /* initial key from client, forget previous state */
+#define P_CONTROL_HARD_RESET_SERVER_V1 2     /* initial key from server, forget previous state */
+#define P_CONTROL_SOFT_RESET_V1        3     /* new key, graceful transition from old to new key */
+#define P_CONTROL_V1                   4     /* control channel packet (usually TLS ciphertext) */
+#define P_ACK_V1                       5     /* acknowledgement for packets received */
+#define P_DATA_V1                      6     /* data channel packet */
+#define P_DATA_V2                      9     /* data channel packet with peer-id */
+
+/* indicates key_method >= 2 */
+#define P_CONTROL_HARD_RESET_CLIENT_V2 7     /* initial key from client, forget previous state */
+#define P_CONTROL_HARD_RESET_SERVER_V2 8     /* initial key from server, forget previous state */
+
+/* define the range of legal opcodes */
+#define P_FIRST_OPCODE                 1
+#define P_LAST_OPCODE                  9
+
+/*
+ * Set the max number of acknowledgments that can "hitch a ride" on an outgoing
+ * non-P_ACK_V1 control packet.
+ */
+#define CONTROL_SEND_ACK_MAX 4
+
+/*
+ * Define number of buffers for send and receive in the reliability layer.
+ */
+#define TLS_RELIABLE_N_SEND_BUFFERS  4 /* also window size for reliability layer */
+#define TLS_RELIABLE_N_REC_BUFFERS   8
+
+/*
+ * Various timeouts
+ */
+#define TLS_MULTI_REFRESH 15    /* call tls_multi_process once every n seconds */
+#define TLS_MULTI_HORIZON 2     /* call tls_multi_process frequently for n seconds after
+                                 * every packet sent/received action */
+
+/*
+ * The SSL/TLS worker thread will wait at most this many seconds for the
+ * interprocess communication pipe to the main thread to be ready to accept
+ * writes.
+ */
+#define TLS_MULTI_THREAD_SEND_TIMEOUT 5
+
+/* Interval that tls_multi_process should call tls_authentication_status */
+#define TLS_MULTI_AUTH_STATUS_INTERVAL 10
+
+/*
+ * Buffer sizes (also see mtu.h).
+ */
+
+/* Maximum length of OCC options string passed as part of auth handshake */
+#define TLS_OPTIONS_LEN 512
+
+/* Default field in X509 to be username */
+#define X509_USERNAME_FIELD_DEFAULT "CN"
+
+/*
+ * Range of key exchange methods
+ */
+#define KEY_METHOD_MIN 1
+#define KEY_METHOD_MAX 2
+
+/* key method taken from lower 4 bits */
+#define KEY_METHOD_MASK 0x0F
+
+/*
+ * Measure success rate of TLS handshakes, for debugging only
+ */
+/* #define MEASURE_TLS_HANDSHAKE_STATS */
+
+/*
+ * Used in --mode server mode to check tls-auth signature on initial
+ * packets received from new clients.
+ */
+struct tls_auth_standalone
+{
+    struct tls_wrap_ctx tls_wrap;
+    struct frame frame;
+};
+
+/*
+ * Prepare the SSL library for use
+ */
+void init_ssl_lib(void);
+
+/*
+ * Free any internal state that the SSL library might have
+ */
+void free_ssl_lib(void);
+
+/**
+ * Build master SSL context object that serves for the whole of OpenVPN
+ * instantiation
+ */
+void init_ssl(const struct options *options, struct tls_root_ctx *ctx);
+
+/** @addtogroup control_processor
+ *  @{ */
+
+/** @name Functions for initialization and cleanup of tls_multi structures
+ *  @{ */
+
+/**
+ * Allocate and initialize a \c tls_multi structure.
+ * @ingroup control_processor
+ *
+ * This function allocates a new \c tls_multi structure, and performs some
+ * amount of initialization.  Afterwards, the \c tls_multi_init_finalize()
+ * function must be called to finalize the structure's initialization
+ * process.
+ *
+ * @param tls_options  - The configuration options to be used for this VPN
+ *                       tunnel.
+ *
+ * @return A newly allocated and initialized \c tls_multi structure.
+ */
+struct tls_multi *tls_multi_init(struct tls_options *tls_options);
+
+/**
+ * Finalize initialization of a \c tls_multi structure.
+ * @ingroup control_processor
+ *
+ * This function initializes the \c TM_ACTIVE \c tls_session, and in
+ * server mode also the \c TM_UNTRUSTED \c tls_session, associated with
+ * this \c tls_multi structure.  It also configures the control channel's
+ * \c frame structure based on the data channel's \c frame given in
+ * argument \a frame.
+ *
+ * @param multi        - The \c tls_multi structure of which to finalize
+ *                       initialization.
+ * @param frame        - The data channel's \c frame structure.
+ */
+void tls_multi_init_finalize(struct tls_multi *multi,
+                             const struct frame *frame);
+
+/*
+ * Initialize a standalone tls-auth verification object.
+ */
+struct tls_auth_standalone *tls_auth_standalone_init(struct tls_options *tls_options,
+                                                     struct gc_arena *gc);
+
+/*
+ * Finalize a standalone tls-auth verification object.
+ */
+void tls_auth_standalone_finalize(struct tls_auth_standalone *tas,
+                                  const struct frame *frame);
+
+/*
+ * Set local and remote option compatibility strings.
+ * Used to verify compatibility of local and remote option
+ * sets.
+ */
+void tls_multi_init_set_options(struct tls_multi *multi,
+                                const char *local,
+                                const char *remote);
+
+/**
+ * Cleanup a \c tls_multi structure and free associated memory
+ * allocations.
+ * @ingroup control_processor
+ *
+ * This function cleans up a \c tls_multi structure.  This includes
+ * cleaning up all associated \c tls_session structures.
+ *
+ * @param multi        - The \c tls_multi structure to clean up in free.
+ * @param clear        - Whether the memory allocated for the \a multi
+ *                       object should be overwritten with 0s.
+ */
+void tls_multi_free(struct tls_multi *multi, bool clear);
+
+/** @} name Functions for initialization and cleanup of tls_multi structures */
+
+/** @} addtogroup control_processor */
+
+#define TLSMP_INACTIVE 0
+#define TLSMP_ACTIVE   1
+#define TLSMP_KILL     2
+
+/*
+ * Called by the top-level event loop.
+ *
+ * Basically decides if we should call tls_process for
+ * the active or untrusted sessions.
+ */
+int tls_multi_process(struct tls_multi *multi,
+                      struct buffer *to_link,
+                      struct link_socket_actual **to_link_addr,
+                      struct link_socket_info *to_link_socket_info,
+                      interval_t *wakeup);
+
+
+/**************************************************************************/
+/**
+ * Determine whether an incoming packet is a data channel or control
+ * channel packet, and process accordingly.
+ * @ingroup external_multiplexer
+ *
+ * When OpenVPN is in TLS mode, this is the first function to process an
+ * incoming packet.  It inspects the packet's one-byte header which
+ * contains the packet's opcode and key ID.  Depending on the opcode, the
+ * packet is processed as a data channel or as a control channel packet.
+ *
+ * @par Data channel packets
+ *
+ * If the opcode indicates the packet is a data channel packet, then the
+ * packet's key ID is used to find the local TLS state it is associated
+ * with.  This state is checked whether it is active, authenticated, and
+ * its remote peer is the source of this packet.  If these checks passed,
+ * the state's security parameters are loaded into the \a opt crypto
+ * options so that \p openvpn_decrypt() can later use them to authenticate
+ * and decrypt the packet.
+ *
+ * This function then returns false.  The \a buf buffer has not been
+ * modified, except for removing the header.
+ *
+ * @par Control channel packets
+ *
+ * If the opcode indicates the packet is a control channel packet, then
+ * this function will process it based on its plaintext header. depending
+ * on the packet's opcode and session ID this function determines if it is
+ * destined for an active TLS session, or whether a new TLS session should
+ * be started.  This function also initiates data channel session key
+ * renegotiation if the received opcode requests that.
+ *
+ * If the incoming packet is destined for an active TLS session, then the
+ * packet is inserted into the Reliability Layer and will be handled
+ * later.
+ *
+ * @param multi - The TLS multi structure associated with the VPN tunnel
+ *     of this packet.
+ * @param from - The source address of the packet.
+ * @param buf - A buffer structure containing the incoming packet.
+ * @param opt - Returns a crypto options structure with the appropriate security
+ *     parameters to handle the packet if it is a data channel packet.
+ * @param ad_start - Returns a pointer to the start of the authenticated data of
+ *     of this packet
+ *
+ * @return
+ * @li True if the packet is a control channel packet that has been
+ *     processed successfully.
+ * @li False if the packet is a data channel packet, or if an error
+ *     occurred during processing of a control channel packet.
+ */
+bool tls_pre_decrypt(struct tls_multi *multi,
+                     const struct link_socket_actual *from,
+                     struct buffer *buf,
+                     struct crypto_options **opt,
+                     bool floated,
+                     const uint8_t **ad_start);
+
+
+/**************************************************************************/
+/** @name Functions for managing security parameter state for data channel packets
+ *  @{ */
+
+/**
+ * Inspect an incoming packet for which no VPN tunnel is active, and
+ * determine whether a new VPN tunnel should be created.
+ * @ingroup data_crypto
+ *
+ * This function receives the initial incoming packet from a client that
+ * wishes to establish a new VPN tunnel, and determines the packet is a
+ * valid initial packet.  It is only used when OpenVPN is running in
+ * server mode.
+ *
+ * The tests performed by this function are whether the packet's opcode is
+ * correct for establishing a new VPN tunnel, whether its key ID is 0, and
+ * whether its size is not too large.  This function also performs the
+ * initial HMAC firewall test, if configured to do so.
+ *
+ * The incoming packet and the local VPN tunnel state are not modified by
+ * this function.  Its sole purpose is to inspect the packet and determine
+ * whether a new VPN tunnel should be created.  If so, that new VPN tunnel
+ * instance will handle processing of the packet.
+ *
+ * @param tas - The standalone TLS authentication setting structure for
+ *     this process.
+ * @param from - The source address of the packet.
+ * @param buf - A buffer structure containing the incoming packet.
+ *
+ * @return
+ * @li True if the packet is valid and a new VPN tunnel should be created
+ *     for this client.
+ * @li False if the packet is not valid, did not pass the HMAC firewall
+ *     test, or some other error occurred.
+ */
+bool tls_pre_decrypt_lite(const struct tls_auth_standalone *tas,
+                          const struct link_socket_actual *from,
+                          const struct buffer *buf);
+
+
+/**
+ * Choose the appropriate security parameters with which to process an
+ * outgoing packet.
+ * @ingroup data_crypto
+ *
+ * If no appropriate security parameters can be found, or if some other
+ * error occurs, then the buffer is set to empty, and the parameters to a NULL
+ * pointer.
+ *
+ * @param multi - The TLS state for this packet's destination VPN tunnel.
+ * @param buf - The buffer containing the outgoing packet.
+ * @param opt - Returns a crypto options structure with the security parameters.
+ */
+void tls_pre_encrypt(struct tls_multi *multi,
+                     struct buffer *buf, struct crypto_options **opt);
+
+
+/**
+ * Prepend a one-byte OpenVPN data channel P_DATA_V1 opcode to the packet.
+ *
+ * The opcode identifies the packet as a V1 data channel packet and gives the
+ * low-permutation version of the key-id to the recipient, so it knows which
+ * decrypt key to use.
+ *
+ * @param multi - The TLS state for this packet's destination VPN tunnel.
+ * @param buf - The buffer to write the header to.
+ *
+ * @ingroup data_crypto
+ */
+void
+tls_prepend_opcode_v1(const struct tls_multi *multi, struct buffer *buf);
+
+/**
+ * Prepend an OpenVPN data channel P_DATA_V2 header to the packet.  The
+ * P_DATA_V2 header consists of a 1-byte opcode, followed by a 3-byte peer-id.
+ *
+ * The opcode identifies the packet as a V2 data channel packet and gives the
+ * low-permutation version of the key-id to the recipient, so it knows which
+ * decrypt key to use.
+ *
+ * The peer-id is sent by clients to servers to help the server determine to
+ * select the decrypt key when the client is roaming between addresses/ports.
+ *
+ * @param multi - The TLS state for this packet's destination VPN tunnel.
+ * @param buf - The buffer to write the header to.
+ *
+ * @ingroup data_crypto
+ */
+void
+tls_prepend_opcode_v2(const struct tls_multi *multi, struct buffer *buf);
+
+/**
+ * Perform some accounting for the key state used.
+ * @ingroup data_crypto
+ *
+ * @param multi - The TLS state for this packet's destination VPN tunnel.
+ * @param buf - The buffer containing the outgoing packet.
+ */
+void tls_post_encrypt(struct tls_multi *multi, struct buffer *buf);
+
+/** @} name Functions for managing security parameter state for data channel packets */
+
+/*
+ * Setup private key file password. If auth_file is given, use the
+ * credentials stored in the file.
+ */
+void pem_password_setup(const char *auth_file);
+
+/*
+ * Setup authentication username and password. If auth_file is given, use the
+ * credentials stored in the file.
+ */
+void auth_user_pass_setup(const char *auth_file, const struct static_challenge_info *sc_info);
+
+/*
+ * Ensure that no caching is performed on authentication information
+ */
+void ssl_set_auth_nocache(void);
+
+/*
+ * Purge any stored authentication information, both for key files and tunnel
+ * authentication. If PCKS #11 is enabled, purge authentication for that too.
+ */
+void ssl_purge_auth(const bool auth_user_pass_only);
+
+void ssl_set_auth_token(const char *token);
+
+#ifdef ENABLE_CLIENT_CR
+/*
+ * ssl_get_auth_challenge will parse the server-pushed auth-failed
+ * reason string and return a dynamically allocated
+ * auth_challenge_info struct.
+ */
+void ssl_purge_auth_challenge(void);
+
+bool ssl_clean_auth_token(void);
+
+void ssl_put_auth_challenge(const char *cr_str);
+
+#endif
+
+/*
+ * Reserve any extra space required on frames.
+ */
+void tls_adjust_frame_parameters(struct frame *frame);
+
+/*
+ * Send a payload over the TLS control channel
+ */
+bool tls_send_payload(struct tls_multi *multi,
+                      const uint8_t *data,
+                      int size);
+
+/*
+ * Receive a payload through the TLS control channel
+ */
+bool tls_rec_payload(struct tls_multi *multi,
+                     struct buffer *buf);
+
+/**
+ * Updates remote address in TLS sessions.
+ *
+ * @param multi - Tunnel to update
+ * @param addr - new address
+ */
+void tls_update_remote_addr(struct tls_multi *multi,
+                            const struct link_socket_actual *addr);
+
+/**
+ * Update TLS session crypto parameters (cipher and auth) and derive data
+ * channel keys based on the supplied options. Does nothing if keys are already
+ * generated.
+ *
+ * @param session         The TLS session to update.
+ * @param options         The options to use when updating session.
+ * @param frame           The frame options for this session (frame overhead is
+ *                        adjusted based on the selected cipher/auth).
+ * @param frame_fragment  The fragment frame options.
+ *
+ * @return true if updating succeeded or keys are already generated, false otherwise.
+ */
+bool tls_session_update_crypto_params(struct tls_session *session,
+                                      struct options *options,
+                                      struct frame *frame,
+                                      struct frame *frame_fragment);
+
+/**
+ * "Poor man's NCP": Use peer cipher if it is an allowed (NCP) cipher.
+ * Allows non-NCP peers to upgrade their cipher individually.
+ *
+ * Make sure to call tls_session_update_crypto_params() after calling this
+ * function.
+ */
+void tls_poor_mans_ncp(struct options *o, const char *remote_ciphername);
+
+#ifdef MANAGEMENT_DEF_AUTH
+static inline char *
+tls_get_peer_info(const struct tls_multi *multi)
+{
+    return multi->peer_info;
+}
+#endif
+
+/**
+ * Return the Negotiable Crypto Parameters version advertised in the peer info
+ * string, or 0 if none specified.
+ */
+int tls_peer_info_ncp_ver(const char *peer_info);
+
+/**
+ * Check whether the ciphers in the supplied list are supported.
+ *
+ * @param list          Colon-separated list of ciphers
+ *
+ * @returns true iff all ciphers in list are supported.
+ */
+bool tls_check_ncp_cipher_list(const char *list);
+
+/**
+ * Return true iff item is present in the colon-separated zero-terminated
+ * cipher list.
+ */
+bool tls_item_in_cipher_list(const char *item, const char *list);
+
+
+/*
+ * inline functions
+ */
+
+static inline bool
+tls_initial_packet_received(const struct tls_multi *multi)
+{
+    return multi->n_sessions > 0;
+}
+
+static inline bool
+tls_test_auth_deferred_interval(const struct tls_multi *multi)
+{
+    if (multi)
+    {
+        const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
+        return now < ks->auth_deferred_expire;
+    }
+    return false;
+}
+
+static inline int
+tls_test_payload_len(const struct tls_multi *multi)
+{
+    if (multi)
+    {
+        const struct key_state *ks = &multi->session[TM_ACTIVE].key[KS_PRIMARY];
+        if (ks->state >= S_ACTIVE)
+        {
+            return BLEN(&ks->plaintext_read_buf);
+        }
+    }
+    return 0;
+}
+
+static inline void
+tls_set_single_session(struct tls_multi *multi)
+{
+    if (multi)
+    {
+        multi->opt.single_session = true;
+    }
+}
+
+/*
+ * protocol_dump() flags
+ */
+#define PD_TLS_AUTH_HMAC_SIZE_MASK 0xFF
+#define PD_SHOW_DATA               (1<<8)
+#define PD_TLS                     (1<<9)
+#define PD_VERBOSE                 (1<<10)
+
+const char *protocol_dump(struct buffer *buffer,
+                          unsigned int flags,
+                          struct gc_arena *gc);
+
+/*
+ * debugging code
+ */
+
+#ifdef MEASURE_TLS_HANDSHAKE_STATS
+void show_tls_performance_stats(void);
+
+#endif
+
+/*#define EXTRACT_X509_FIELD_TEST*/
+void extract_x509_field_test(void);
+
+/**
+ * Given a key_method, return true if opcode represents the required form of
+ * hard_reset.
+ *
+ * If key_method == 0, return true if any form of hard reset is used.
+ */
+bool is_hard_reset(int op, int key_method);
+
+void delayed_auth_pass_purge(void);
+
+
+/*
+ * Show the TLS ciphers that are available for us to use in the SSL
+ * library with headers hinting their usage and warnings about usage.
+ *
+ * @param cipher_list       list of allowed TLS cipher, or NULL.
+ * @param cipher_list_tls13 list of allowed TLS 1.3+ cipher, or NULL
+ * @param tls_cert_profile  TLS certificate crypto profile name.
+ */
+void
+show_available_tls_ciphers(const char *cipher_list,
+                           const char *cipher_list_tls13,
+                           const char *tls_cert_profile);
+#endif /* ENABLE_CRYPTO */
+
+#endif /* ifndef OPENVPN_SSL_H */
diff --git a/src/openvpn/ssl_backend.h b/src/openvpn/ssl_backend.h
new file mode 100644
index 0000000..c614efa
--- /dev/null
+++ b/src/openvpn/ssl_backend.h
@@ -0,0 +1,561 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel SSL library backend module
+ */
+
+
+#ifndef SSL_BACKEND_H_
+#define SSL_BACKEND_H_
+
+#include "buffer.h"
+
+#ifdef ENABLE_CRYPTO_OPENSSL
+#include "ssl_openssl.h"
+#include "ssl_verify_openssl.h"
+#define SSLAPI SSLAPI_OPENSSL
+#endif
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include "ssl_mbedtls.h"
+#include "ssl_verify_mbedtls.h"
+#define SSLAPI SSLAPI_MBEDTLS
+#endif
+
+/* Ensure that SSLAPI got a sane value if SSL is disabled or unknown */
+#ifndef SSLAPI
+#define SSLAPI SSLAPI_NONE
+#endif
+
+/**
+ *  prototype for struct tls_session from ssl_common.h
+ */
+struct tls_session;
+
+/**
+ * Get a tls_cipher_name_pair containing OpenSSL and IANA names for supplied TLS cipher name
+ *
+ * @param cipher_name   Can be either OpenSSL or IANA cipher name
+ * @return              tls_cipher_name_pair* if found, NULL otherwise
+ */
+typedef struct { const char *openssl_name; const char *iana_name; } tls_cipher_name_pair;
+const tls_cipher_name_pair *tls_get_cipher_name_pair(const char *cipher_name, size_t len);
+
+/*
+ *
+ * Functions implemented in ssl.c for use by the backend SSL library
+ *
+ */
+
+/**
+ * Callback to retrieve the user's password
+ *
+ * @param buf           Buffer to return the password in
+ * @param size          Size of the buffer
+ * @param rwflag        Unused, needed for OpenSSL compatibility
+ * @param u             Unused, needed for OpenSSL compatibility
+ */
+int pem_password_callback(char *buf, int size, int rwflag, void *u);
+
+/*
+ *
+ * Functions used in ssl.c which must be implemented by the backend SSL library
+ *
+ */
+
+/**
+ * Perform any static initialisation necessary by the library.
+ * Called on OpenVPN initialisation
+ */
+void tls_init_lib(void);
+
+/**
+ * Free any global SSL library-specific data structures.
+ */
+void tls_free_lib(void);
+
+/**
+ * Clear the underlying SSL library's error state.
+ */
+void tls_clear_error(void);
+
+/**
+ * Parse a TLS version specifier
+ *
+ * @param vstr          The TLS version string
+ * @param extra         An optional extra parameter, may be NULL
+ *
+ * @return              One of the TLS_VER_x constants or TLS_VER_BAD
+ *                      if a parse error should be flagged.
+ */
+#define TLS_VER_BAD    -1
+#define TLS_VER_UNSPEC  0 /* default */
+#define TLS_VER_1_0     1
+#define TLS_VER_1_1     2
+#define TLS_VER_1_2     3
+#define TLS_VER_1_3     4
+int tls_version_parse(const char *vstr, const char *extra);
+
+/**
+ * Return the maximum TLS version (as a TLS_VER_x constant)
+ * supported by current SSL implementation
+ *
+ * @return              One of the TLS_VER_x constants (but not TLS_VER_BAD).
+ */
+int tls_version_max(void);
+
+#ifdef ENABLE_CRYPTO
+
+/**
+ * Initialise a library-specific TLS context for a server.
+ *
+ * @param ctx           TLS context to initialise
+ */
+void tls_ctx_server_new(struct tls_root_ctx *ctx);
+
+/**
+ * Initialises a library-specific TLS context for a client.
+ *
+ * @param ctx           TLS context to initialise
+ */
+void tls_ctx_client_new(struct tls_root_ctx *ctx);
+
+/**
+ * Frees the library-specific TLSv1 context
+ *
+ * @param ctx           TLS context to free
+ */
+void tls_ctx_free(struct tls_root_ctx *ctx);
+
+/**
+ * Checks whether the given TLS context is initialised
+ *
+ * @param ctx           TLS context to check
+ *
+ * @return      true if the context is initialised, false if not.
+ */
+bool tls_ctx_initialised(struct tls_root_ctx *ctx);
+
+/**
+ * Set any library specific options.
+ *
+ * Examples include disabling session caching, the password callback to use,
+ * and session verification parameters.
+ *
+ * @param ctx           TLS context to set options on
+ * @param ssl_flags     SSL flags to set
+ *
+ * @return true on success, false otherwise.
+ */
+bool tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags);
+
+/**
+ * Restrict the list of ciphers that can be used within the TLS context for TLS 1.2
+ * and below
+ *
+ * @param ctx           TLS context to restrict, must be valid.
+ * @param ciphers       String containing : delimited cipher names, or NULL to use
+ *                                      sane defaults.
+ */
+void tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers);
+
+/**
+ * Restrict the list of ciphers that can be used within the TLS context for TLS 1.3
+ * and higher
+ *
+ * @param ctx           TLS context to restrict, must be valid.
+ * @param ciphers       String containing : delimited cipher names, or NULL to use
+ *                                      sane defaults.
+ */
+void tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers);
+
+/**
+ * Set the TLS certificate profile.  The profile defines which crypto
+ * algorithms may be used in the supplied certificate.
+ *
+ * @param ctx           TLS context to restrict, must be valid.
+ * @param profile       The profile name ('preferred', 'legacy' or 'suiteb').
+ *                      Defaults to 'preferred' if NULL.
+ */
+void tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile);
+
+/**
+ * Check our certificate notBefore and notAfter fields, and warn if the cert is
+ * either not yet valid or has expired.  Note that this is a non-fatal error,
+ * since we compare against the system time, which might be incorrect.
+ *
+ * @param ctx           TLS context to get our certificate from.
+ */
+void tls_ctx_check_cert_time(const struct tls_root_ctx *ctx);
+
+/**
+ * Load Diffie Hellman Parameters, and load them into the library-specific
+ * TLS context.
+ *
+ * @param ctx                   TLS context to use
+ * @param dh_file               The file name to load the parameters from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param dh_file_inline        A string containing the parameters
+ */
+void tls_ctx_load_dh_params(struct tls_root_ctx *ctx, const char *dh_file,
+                            const char *dh_file_inline);
+
+/**
+ * Load Elliptic Curve Parameters, and load them into the library-specific
+ * TLS context.
+ *
+ * @param ctx          TLS context to use
+ * @param curve_name   The name of the elliptic curve to load.
+ */
+void tls_ctx_load_ecdh_params(struct tls_root_ctx *ctx, const char *curve_name
+                              );
+
+/**
+ * Load PKCS #12 file for key, cert and (optionally) CA certs, and add to
+ * library-specific TLS context.
+ *
+ * @param ctx                   TLS context to use
+ * @param pkcs12_file           The file name to load the information from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param pkcs12_file_inline    A string containing the information
+ *
+ * @return                      1 if an error occurred, 0 if parsing was
+ *                              successful.
+ */
+int tls_ctx_load_pkcs12(struct tls_root_ctx *ctx, const char *pkcs12_file,
+                        const char *pkcs12_file_inline, bool load_ca_file
+                        );
+
+/**
+ * Use Windows cryptoapi for key and cert, and add to library-specific TLS
+ * context.
+ *
+ * @param ctx                   TLS context to use
+ * @param crypto_api_cert       String representing the certificate to load.
+ */
+#ifdef ENABLE_CRYPTOAPI
+void tls_ctx_load_cryptoapi(struct tls_root_ctx *ctx, const char *cryptoapi_cert);
+
+#endif /* _WIN32 */
+
+/**
+ * Load certificate file into the given TLS context. If the given certificate
+ * file contains a certificate chain, load the whole chain.
+ *
+ * @param ctx                   TLS context to use
+ * @param cert_file             The file name to load the certificate from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param cert_file_inline      A string containing the certificate
+ */
+void tls_ctx_load_cert_file(struct tls_root_ctx *ctx, const char *cert_file,
+                            const char *cert_file_inline);
+
+/**
+ * Load private key file into the given TLS context.
+ *
+ * @param ctx                   TLS context to use
+ * @param priv_key_file         The file name to load the private key from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param priv_key_file_inline  A string containing the private key
+ *
+ * @return                      1 if an error occurred, 0 if parsing was
+ *                              successful.
+ */
+int tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const char *priv_key_file,
+                           const char *priv_key_file_inline
+                           );
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+/**
+ * Tell the management interface to load the given certificate and the external
+ * private key matching the given certificate.
+ *
+ * @param ctx                   TLS context to use
+ * @param cert_file             The file name to load the certificate from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param cert_file_inline      A string containing the certificate
+ *
+ * @return                      1 if an error occurred, 0 if parsing was
+ *                              successful.
+ */
+int tls_ctx_use_external_private_key(struct tls_root_ctx *ctx,
+                                     const char *cert_file, const char *cert_file_inline);
+
+#endif
+
+
+/**
+ * Load certificate authority certificates from the given file or path.
+ *
+ * Note that not all SSL libraries support loading from a path.
+ *
+ * @param ctx                   TLS context to use
+ * @param ca_file               The file name to load the CAs from, or
+ *                              "[[INLINE]]" in the case of inline files.
+ * @param ca_file_inline        A string containing the CAs
+ * @param ca_path               The path to load the CAs from
+ */
+void tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
+                     const char *ca_file_inline, const char *ca_path, bool tls_server
+                     );
+
+/**
+ * Load extra certificate authority certificates from the given file or path.
+ * These Load extra certificates that are part of our own certificate
+ * chain but shouldn't be included in the verify chain.
+ *
+ *
+ * @param ctx                           TLS context to use
+ * @param extra_certs_file              The file name to load the certs from, or
+ *                                      "[[INLINE]]" in the case of inline files.
+ * @param extra_certs_file_inline       A string containing the certs
+ */
+void tls_ctx_load_extra_certs(struct tls_root_ctx *ctx, const char *extra_certs_file,
+                              const char *extra_certs_file_inline
+                              );
+
+#ifdef ENABLE_CRYPTO_MBEDTLS
+/**
+ * Add a personalisation string to the mbed TLS RNG, based on the certificate
+ * loaded into the given context.
+ *
+ * @param ctx                   TLS context to use
+ */
+void tls_ctx_personalise_random(struct tls_root_ctx *ctx);
+
+#endif
+
+/* **************************************
+ *
+ * Key-state specific functions
+ *
+ ***************************************/
+
+/**
+ * Initialise the SSL channel part of the given key state. Settings will be
+ * loaded from a previously initialised TLS context.
+ *
+ * @param ks_ssl        The SSL channel's state info to initialise
+ * @param ssl_ctx       The TLS context to use when initialising the channel.
+ * @param is_server     Initialise a server?
+ * @param session       The session associated with the given key_state
+ */
+void key_state_ssl_init(struct key_state_ssl *ks_ssl,
+                        const struct tls_root_ctx *ssl_ctx, bool is_server, struct tls_session *session);
+
+/**
+ * Free the SSL channel part of the given key state.
+ *
+ * @param ks_ssl        The SSL channel's state info to free
+ */
+void key_state_ssl_free(struct key_state_ssl *ks_ssl);
+
+/**
+ * Reload the Certificate Revocation List for the SSL channel
+ *
+ * @param ssl_ctx       The TLS context to use when reloading the CRL
+ * @param crl_file      The file name to load the CRL from, or
+ *                      "[[INLINE]]" in the case of inline files.
+ * @param crl_inline    A string containing the CRL
+ */
+void backend_tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx,
+                                const char *crl_file, const char *crl_inline);
+
+/**
+ * Keying Material Exporters [RFC 5705] allows additional keying material to be
+ * derived from existing TLS channel. This exported keying material can then be
+ * used for a variety of purposes.
+ *
+ * @param ks_ssl       The SSL channel's state info
+ * @param session      The session associated with the given key_state
+ */
+
+void
+key_state_export_keying_material(struct key_state_ssl *ks_ssl,
+                                 struct tls_session *session) __attribute__((nonnull));
+
+/**************************************************************************/
+/** @addtogroup control_tls
+ *  @{ */
+
+/** @name Functions for packets to be sent to a remote OpenVPN peer
+ *  @{ */
+
+/**
+ * Insert a plaintext buffer into the TLS module.
+ *
+ * After successfully processing the data, the data in \a buf is zeroized,
+ * its length set to zero, and a value of \c 1 is returned.
+ *
+ * @param ks_ssl       - The security parameter state for this %key
+ *                       session.
+ * @param buf          - The plaintext message to process.
+ *
+ * @return The return value indicates whether the data was successfully
+ *     processed:
+ * - \c 1: All the data was processed successfully.
+ * - \c 0: The data was not processed, this function should be called
+ *   again later to retry.
+ * - \c -1: An error occurred.
+ */
+int key_state_write_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf);
+
+/**
+ * Insert plaintext data into the TLS module.
+ *
+ * @param ks_ssl       - The security parameter state for this %key
+ *                       session.
+ * @param data         - A pointer to the data to process.
+ * @param len          - The length in bytes of the data to process.
+ *
+ * @return The return value indicates whether the data was successfully
+ *     processed:
+ * - \c 1: All the data was processed successfully.
+ * - \c 0: The data was not processed, this function should be called
+ *   again later to retry.
+ * - \c -1: An error occurred.
+ */
+int key_state_write_plaintext_const(struct key_state_ssl *ks_ssl,
+                                    const uint8_t *data, int len);
+
+/**
+ * Extract ciphertext data from the TLS module.
+ *
+ * If the \a buf buffer has a length other than zero, this function does
+ * not perform any action and returns 0.
+ *
+ * @param ks_ssl       - The security parameter state for this %key
+ *                       session.
+ * @param buf          - A buffer in which to store the ciphertext.
+ * @param maxlen       - The maximum number of bytes to extract.
+ *
+ * @return The return value indicates whether the data was successfully
+ *     processed:
+ * - \c 1: Data was extracted successfully.
+ * - \c 0: No data was extracted, this function should be called again
+ *   later to retry.
+ * - \c -1: An error occurred.
+ */
+int key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf,
+                              int maxlen);
+
+/** @} name Functions for packets to be sent to a remote OpenVPN peer */
+
+
+/** @name Functions for packets received from a remote OpenVPN peer
+ *  @{ */
+
+/**
+ * Insert a ciphertext buffer into the TLS module.
+ *
+ * After successfully processing the data, the data in \a buf is zeroized,
+ * its length set to zero, and a value of \c 1 is returned.
+ *
+ * @param ks_ssl       - The security parameter state for this %key
+ *                       session.
+ * @param buf          - The ciphertext message to process.
+ *
+ * @return The return value indicates whether the data was successfully
+ *     processed:
+ * - \c 1: All the data was processed successfully.
+ * - \c 0: The data was not processed, this function should be called
+ *   again later to retry.
+ * - \c -1: An error occurred.
+ */
+int key_state_write_ciphertext(struct key_state_ssl *ks_ssl,
+                               struct buffer *buf);
+
+/**
+ * Extract plaintext data from the TLS module.
+ *
+ * If the \a buf buffer has a length other than zero, this function does
+ * not perform any action and returns 0.
+ *
+ * @param ks_ssl       - The security parameter state for this %key
+ *                       session.
+ * @param buf          - A buffer in which to store the plaintext.
+ * @param maxlen       - The maximum number of bytes to extract.
+ *
+ * @return The return value indicates whether the data was successfully
+ *     processed:
+ * - \c 1: Data was extracted successfully.
+ * - \c 0: No data was extracted, this function should be called again
+ *   later to retry.
+ * - \c -1: An error occurred.
+ */
+int key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf,
+                             int maxlen);
+
+/** @} name Functions for packets received from a remote OpenVPN peer */
+
+/** @} addtogroup control_tls */
+
+/* **************************************
+ *
+ * Information functions
+ *
+ * Print information for the end user.
+ *
+ ***************************************/
+
+/*
+ * Print a one line summary of SSL/TLS session handshake.
+ */
+void print_details(struct key_state_ssl *ks_ssl, const char *prefix);
+
+/*
+ * Show the TLS ciphers that are available for us to use in the
+ * library depending on the TLS version. This function prints
+ * a list of ciphers without headers/footers.
+ *
+ * @param cipher_list       list of allowed TLS cipher, or NULL.
+ * @param tls_cert_profile  TLS certificate crypto profile name.
+ * @param tls13             Select if <=TLS1.2 or TLS1.3+ ciphers
+ *                          should be shown
+ */
+void
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                bool tls13);
+
+/*
+ * Show the available elliptic curves in the crypto library
+ */
+void show_available_curves(void);
+
+/*
+ * The OpenSSL library has a notion of preference in TLS ciphers.  Higher
+ * preference == more secure. Return the highest preference cipher.
+ */
+void get_highest_preference_tls_cipher(char *buf, int size);
+
+/**
+ * return a pointer to a static memory area containing the
+ * name and version number of the SSL library in use
+ */
+const char *get_ssl_library_version(void);
+
+#endif /* ENABLE_CRYPTO */
+#endif /* SSL_BACKEND_H_ */
diff --git a/src/openvpn/ssl_common.h b/src/openvpn/ssl_common.h
new file mode 100644
index 0000000..ac25ffa
--- /dev/null
+++ b/src/openvpn/ssl_common.h
@@ -0,0 +1,559 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Common Data Structures
+ */
+
+#ifndef SSL_COMMON_H_
+#define SSL_COMMON_H_
+
+#include "session_id.h"
+#include "socket.h"
+#include "packet_id.h"
+#include "crypto.h"
+#include "options.h"
+
+#include "ssl_backend.h"
+
+/* passwords */
+#define UP_TYPE_AUTH        "Auth"
+#define UP_TYPE_PRIVATE_KEY "Private Key"
+
+/** @addtogroup control_processor
+ *  @{ */
+/**
+ * @name Control channel negotiation states
+ *
+ * These states represent the different phases of control channel
+ * negotiation between OpenVPN peers.  OpenVPN servers and clients
+ * progress through the states in a different order, because of their
+ * different roles during exchange of random material.  The references to
+ * the \c key_source2 structure in the list below is only valid if %key
+ * method 2 is being used.  See the \link key_generation data channel key
+ * generation\endlink related page for more information.
+ *
+ * Clients follow this order:
+ *   -# \c S_INITIAL, ready to begin three-way handshake and control
+ *      channel negotiation.
+ *   -# \c S_PRE_START, have started three-way handshake, waiting for
+ *      acknowledgment from remote.
+ *   -# \c S_START, initial three-way handshake complete.
+ *   -# \c S_SENT_KEY, have sent local part of \c key_source2 random
+ *      material.
+ *   -# \c S_GOT_KEY, have received remote part of \c key_source2 random
+ *      material.
+ *   -# \c S_ACTIVE, normal operation during remaining handshake window.
+ *   -# \c S_NORMAL_OP, normal operation.
+ *
+ * Servers follow the same order, except for \c S_SENT_KEY and \c
+ * S_GOT_KEY being reversed, because the server first receives the
+ * client's \c key_source2 random material before generating and sending
+ * its own.
+ *
+ * @{
+ */
+#define S_ERROR          -1     /**< Error state.  */
+#define S_UNDEF           0     /**< Undefined state, used after a \c
+                                 *   key_state is cleaned up. */
+#define S_INITIAL         1     /**< Initial \c key_state state after
+                                 *   initialization by \c key_state_init()
+                                 *   before start of three-way handshake. */
+#define S_PRE_START       2     /**< Waiting for the remote OpenVPN peer
+                                 *   to acknowledge during the initial
+                                 *   three-way handshake. */
+#define S_START           3     /**< Three-way handshake is complete,
+                                 *   start of key exchange. */
+#define S_SENT_KEY        4     /**< Local OpenVPN process has sent its
+                                 *   part of the key material. */
+#define S_GOT_KEY         5     /**< Local OpenVPN process has received
+                                 *   the remote's part of the key
+                                 *   material. */
+#define S_ACTIVE          6     /**< Operational \c key_state state
+                                 *   immediately after negotiation has
+                                 *   completed while still within the
+                                 *   handshake window. */
+/* ready to exchange data channel packets */
+#define S_NORMAL_OP       7     /**< Normal operational \c key_state
+                                 *   state. */
+/** @} name Control channel negotiation states */
+/** @} addtogroup control_processor */
+
+/**
+ * Container for one half of random material to be used in %key method 2
+ * \ref key_generation "data channel key generation".
+ * @ingroup control_processor
+ */
+struct key_source {
+    uint8_t pre_master[48];     /**< Random used for master secret
+                                 *   generation, provided only by client
+                                 *   OpenVPN peer. */
+    uint8_t random1[32];        /**< Seed used for master secret
+                                 *   generation, provided by both client
+                                 *   and server. */
+    uint8_t random2[32];        /**< Seed used for key expansion, provided
+                                 *   by both client and server. */
+};
+
+
+/**
+ * Container for both halves of random material to be used in %key method
+ * 2 \ref key_generation "data channel key generation".
+ * @ingroup control_processor
+ */
+struct key_source2 {
+    struct key_source client;   /**< Random provided by client. */
+    struct key_source server;   /**< Random provided by server. */
+};
+
+/**
+ * Security parameter state of one TLS and data channel %key session.
+ * @ingroup control_processor
+ *
+ * This structure represents one security parameter session between
+ * OpenVPN peers.  It includes the control channel TLS state and the data
+ * channel crypto state.  It also contains the reliability layer
+ * structures used for control channel messages.
+ *
+ * A new \c key_state structure is initialized for each hard or soft
+ * reset.
+ *
+ * @see
+ *  - This structure should be initialized using the \c key_state_init()
+ *    function.
+ *  - This structure should be cleaned up using the \c key_state_free()
+ *    function.
+ */
+struct key_state
+{
+    int state;
+
+    /**
+     * Key id for this key_state,  inherited from struct tls_session.
+     * @see tls_session::key_id.
+     */
+    int key_id;
+
+    struct key_state_ssl ks_ssl; /* contains SSL object and BIOs for the control channel */
+
+    time_t established;         /* when our state went S_ACTIVE */
+    time_t must_negotiate;      /* key negotiation times out if not finished before this time */
+    time_t must_die;            /* this object is destroyed at this time */
+
+    int initial_opcode;         /* our initial P_ opcode */
+    struct session_id session_id_remote; /* peer's random session ID */
+    struct link_socket_actual remote_addr; /* peer's IP addr */
+
+    struct crypto_options crypto_options;/* data channel crypto options */
+
+    struct key_source2 *key_src;       /* source entropy for key expansion */
+
+    struct buffer plaintext_read_buf;
+    struct buffer plaintext_write_buf;
+    struct buffer ack_write_buf;
+
+    struct reliable *send_reliable; /* holds a copy of outgoing packets until ACK received */
+    struct reliable *rec_reliable; /* order incoming ciphertext packets before we pass to TLS */
+    struct reliable_ack *rec_ack; /* buffers all packet IDs we want to ACK back to sender */
+
+    struct buffer_list *paybuf;
+
+    counter_type n_bytes;                /* how many bytes sent/recvd since last key exchange */
+    counter_type n_packets;              /* how many packets sent/recvd since last key exchange */
+
+    /*
+     * If bad username/password, TLS connection will come up but 'authenticated' will be false.
+     */
+    bool authenticated;
+    time_t auth_deferred_expire;
+
+#ifdef ENABLE_DEF_AUTH
+    /* If auth_deferred is true, authentication is being deferred */
+    bool auth_deferred;
+#ifdef MANAGEMENT_DEF_AUTH
+    unsigned int mda_key_id;
+    unsigned int mda_status;
+#endif
+#ifdef PLUGIN_DEF_AUTH
+    unsigned int auth_control_status;
+    time_t acf_last_mod;
+    char *auth_control_file;
+#endif
+#endif
+};
+
+/** Control channel wrapping (--tls-auth/--tls-crypt) context */
+struct tls_wrap_ctx
+{
+    enum {
+        TLS_WRAP_NONE = 0, /**< No control channel wrapping */
+        TLS_WRAP_AUTH,  /**< Control channel authentication */
+        TLS_WRAP_CRYPT, /**< Control channel encryption and authentication */
+    } mode;                     /**< Control channel wrapping mode */
+    struct crypto_options opt;  /**< Crypto state */
+    struct buffer work;         /**< Work buffer (only for --tls-crypt) */
+};
+
+/*
+ * Our const options, obtained directly or derived from
+ * command line options.
+ */
+struct tls_options
+{
+    /* our master TLS context from which all SSL objects derived */
+    struct tls_root_ctx ssl_ctx;
+
+    /* data channel cipher, hmac, and key lengths */
+    struct key_type key_type;
+
+    /* true if we are a TLS server, client otherwise */
+    bool server;
+
+    /* if true, don't xmit until first packet from peer is received */
+    bool xmit_hold;
+
+#ifdef ENABLE_OCC
+    /* local and remote options strings
+     * that must match between client and server */
+    const char *local_options;
+    const char *remote_options;
+#endif
+
+    /* from command line */
+    int key_method;
+    bool replay;
+    bool single_session;
+#ifdef ENABLE_OCC
+    bool disable_occ;
+#endif
+    int mode;
+    bool pull;
+#ifdef ENABLE_PUSH_PEER_INFO
+    int push_peer_info_detail;
+#endif
+    int transition_window;
+    int handshake_window;
+    interval_t packet_timeout;
+    int renegotiate_bytes;
+    int renegotiate_packets;
+    interval_t renegotiate_seconds;
+
+    /* cert verification parms */
+    const char *verify_command;
+    const char *verify_export_cert;
+    int verify_x509_type;
+    const char *verify_x509_name;
+    const char *crl_file;
+    const char *crl_file_inline;
+    int ns_cert_type;
+    unsigned remote_cert_ku[MAX_PARMS];
+    const char *remote_cert_eku;
+    uint8_t *verify_hash;
+    hash_algo_type verify_hash_algo;
+    char *x509_username_field;
+
+    /* allow openvpn config info to be
+     * passed over control channel */
+    bool pass_config_info;
+
+    /* struct crypto_option flags */
+    unsigned int crypto_flags;
+
+    int replay_window;                 /* --replay-window parm */
+    int replay_time;                   /* --replay-window parm */
+    bool tcp_mode;
+
+    const char *config_ciphername;
+    const char *config_authname;
+    bool ncp_enabled;
+
+    /** TLS handshake wrapping state */
+    struct tls_wrap_ctx tls_wrap;
+
+    /* frame parameters for TLS control channel */
+    struct frame frame;
+
+    /* used for username/password authentication */
+    const char *auth_user_pass_verify_script;
+    bool auth_user_pass_verify_script_via_file;
+    const char *tmp_dir;
+    const char *auth_user_pass_file;
+    bool auth_token_generate;   /**< Generate auth-tokens on successful user/pass auth,
+                                 *   set via options->auth_token_generate. */
+    unsigned int auth_token_lifetime;
+
+    /* use the client-config-dir as a positive authenticator */
+    const char *client_config_dir_exclusive;
+
+    /* instance-wide environment variable set */
+    struct env_set *es;
+    const struct plugin_list *plugins;
+
+    /* compression parms */
+#ifdef USE_COMP
+    struct compress_options comp_options;
+#endif
+
+    /* configuration file SSL-related boolean and low-permutation options */
+#define SSLF_CLIENT_CERT_NOT_REQUIRED (1<<0)
+#define SSLF_CLIENT_CERT_OPTIONAL     (1<<1)
+#define SSLF_USERNAME_AS_COMMON_NAME  (1<<2)
+#define SSLF_AUTH_USER_PASS_OPTIONAL  (1<<3)
+#define SSLF_OPT_VERIFY               (1<<4)
+#define SSLF_CRL_VERIFY_DIR           (1<<5)
+#define SSLF_TLS_VERSION_MIN_SHIFT    6
+#define SSLF_TLS_VERSION_MIN_MASK     0xF  /* (uses bit positions 6 to 9) */
+#define SSLF_TLS_VERSION_MAX_SHIFT    10
+#define SSLF_TLS_VERSION_MAX_MASK     0xF  /* (uses bit positions 10 to 13) */
+    unsigned int ssl_flags;
+
+#ifdef MANAGEMENT_DEF_AUTH
+    struct man_def_auth_context *mda_context;
+#endif
+
+    const struct x509_track *x509_track;
+
+#ifdef ENABLE_CLIENT_CR
+    const struct static_challenge_info *sci;
+#endif
+
+    /* --gremlin bits */
+    int gremlin;
+
+    /* Keying Material Exporter [RFC 5705] parameters */
+    const char *ekm_label;
+    size_t ekm_label_size;
+    size_t ekm_size;
+};
+
+/** @addtogroup control_processor
+ *  @{ */
+/** @name Index of key_state objects within a tls_session structure
+ *
+ *  This is the index of \c tls_session.key
+ *
+ *  @{ */
+#define KS_PRIMARY    0         /**< Primary %key state index. */
+#define KS_LAME_DUCK  1         /**< %Key state index that will retire
+                                 *   soon. */
+#define KS_SIZE       2         /**< Size of the \c tls_session.key array. */
+/** @} name Index of key_state objects within a tls_session structure */
+/** @} addtogroup control_processor */
+
+#define AUTH_TOKEN_SIZE 32      /**< Size of server side generated auth tokens.
+                                 *   32 bytes == 256 bits
+                                 */
+
+/**
+ * Security parameter state of a single session within a VPN tunnel.
+ * @ingroup control_processor
+ *
+ * This structure represents an OpenVPN peer-to-peer control channel
+ * session.
+ *
+ * A \c tls_session remains over soft resets, but a new instance is
+ * initialized for each hard reset.
+ *
+ * @see
+ *  - This structure should be initialized using the \c tls_session_init()
+ *    function.
+ *  - This structure should be cleaned up using the \c tls_session_free()
+ *    function.
+ */
+struct tls_session
+{
+    /* const options and config info */
+    struct tls_options *opt;
+
+    /* during hard reset used to control burst retransmit */
+    bool burst;
+
+    /* authenticate control packets */
+    struct tls_wrap_ctx tls_wrap;
+
+    int initial_opcode;         /* our initial P_ opcode */
+    struct session_id session_id; /* our random session ID */
+
+    /**
+     * The current active key id, used to keep track of renegotiations.
+     * key_id increments with each soft reset to KEY_ID_MASK then recycles back
+     * to 1.  This way you know that if key_id is 0, it is the first key.
+     */
+    int key_id;
+
+    int limit_next;             /* used for traffic shaping on the control channel */
+
+    int verify_maxlevel;
+
+    char *common_name;
+
+    struct cert_hash_set *cert_hash_set;
+
+#ifdef ENABLE_PF
+    uint32_t common_name_hashval;
+#endif
+
+    bool verified;              /* true if peer certificate was verified against CA */
+
+    /* not-yet-authenticated incoming client */
+    struct link_socket_actual untrusted_addr;
+
+    struct key_state key[KS_SIZE];
+};
+
+/** @addtogroup control_processor
+ *  @{ */
+/** @name Index of tls_session objects within a tls_multi structure
+ *
+ *  This is the index of \c tls_multi.session
+ *
+ *  Normally three tls_session objects are maintained by an active openvpn
+ *  session.  The first is the current, TLS authenticated session, the
+ *  second is used to process connection requests from a new client that
+ *  would usurp the current session if successfully authenticated, and the
+ *  third is used as a repository for a "lame-duck" %key in the event that
+ *  the primary session resets due to error while the lame-duck %key still
+ *  has time left before its expiration.  Lame duck keys are used to
+ *  maintain the continuity of the data channel connection while a new %key
+ *  is being negotiated.
+ *
+ *  @{ */
+#define TM_ACTIVE    0          /**< Active \c tls_session. */
+#define TM_UNTRUSTED 1          /**< As yet un-trusted \c tls_session
+                                 *   being negotiated. */
+#define TM_LAME_DUCK 2          /**< Old \c tls_session. */
+#define TM_SIZE      3          /**< Size of the \c tls_multi.session
+                                 *   array. */
+/** @} name Index of tls_session objects within a tls_multi structure */
+/** @} addtogroup control_processor */
+
+
+/*
+ * The number of keys we will scan on encrypt or decrypt.  The first
+ * is the "active" key.  The second is the lame_duck or retiring key
+ * associated with the active key's session ID.  The third is a detached
+ * lame duck session that only occurs in situations where a key renegotiate
+ * failed on the active key, but a lame duck key was still valid.  By
+ * preserving the lame duck session, we can be assured of having a data
+ * channel key available even when network conditions are so bad that
+ * we can't negotiate a new key within the time allotted.
+ */
+#define KEY_SCAN_SIZE 3
+
+
+/**
+ * Security parameter state for a single VPN tunnel.
+ * @ingroup control_processor
+ *
+ * An active VPN tunnel running with TLS enabled has one \c tls_multi
+ * object, in which it stores all control channel and data channel
+ * security parameter state.  This structure can contain multiple,
+ * possibly simultaneously active, \c tls_context objects to allow for
+ * interruption-less transitions during session renegotiations.  Each \c
+ * tls_context represents one control channel session, which can span
+ * multiple data channel security parameter sessions stored in \c
+ * key_state structures.
+ */
+struct tls_multi
+{
+    /* used to coordinate access between main thread and TLS thread */
+    /*MUTEX_PTR_DEFINE (mutex);*/
+
+    /* const options and config info */
+    struct tls_options opt;
+
+    struct key_state *key_scan[KEY_SCAN_SIZE];
+    /**< List of \c key_state objects in the
+     *   order they should be scanned by data
+     *   channel modules. */
+
+    /*
+     * used by tls_pre_encrypt to communicate the encrypt key
+     * to tls_post_encrypt()
+     */
+    struct key_state *save_ks;  /* temporary pointer used between pre/post routines */
+
+    /*
+     * Used to return outgoing address from
+     * tls_multi_process.
+     */
+    struct link_socket_actual to_link_addr;
+
+    int n_sessions;             /**< Number of sessions negotiated thus
+                                 *   far. */
+
+    /*
+     * Number of errors.
+     */
+    int n_hard_errors; /* errors due to TLS negotiation failure */
+    int n_soft_errors; /* errors due to unrecognized or failed-to-authenticate incoming packets */
+
+    /*
+     * Our locked common name, username, and cert hashes (cannot change during the life of this tls_multi object)
+     */
+    char *locked_cn;
+    char *locked_username;
+    struct cert_hash_set *locked_cert_hash_set;
+
+#ifdef ENABLE_DEF_AUTH
+    /*
+     * An error message to send to client on AUTH_FAILED
+     */
+    char *client_reason;
+
+    /* Time of last call to tls_authentication_status */
+    time_t tas_last;
+#endif
+
+#if P2MP_SERVER
+    /*
+     * A multi-line string of general-purpose info received from peer
+     * over control channel.
+     */
+    char *peer_info;
+#endif
+
+    /* For P_DATA_V2 */
+    uint32_t peer_id;
+    bool use_peer_id;
+
+    char *remote_ciphername;    /**< cipher specified in peer's config file */
+
+    char *auth_token;    /**< If server sends a generated auth-token,
+                          *   this is the token to use for future
+                          *   user/pass authentications in this session.
+                          */
+    time_t auth_token_tstamp; /**< timestamp of the generated token */
+    bool auth_token_sent; /**< If server uses --auth-gen-token and
+                           *   token has been sent to client */
+    /*
+     * Our session objects.
+     */
+    struct tls_session session[TM_SIZE];
+    /**< Array of \c tls_session objects
+     *   representing control channel
+     *   sessions with the remote peer. */
+};
+
+#endif /* SSL_COMMON_H_ */
diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
new file mode 100644
index 0000000..4746261
--- /dev/null
+++ b/src/openvpn/ssl_mbedtls.c
@@ -0,0 +1,1424 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *  Copyright (C) 2006-2010, Brainspark B.V.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel mbed TLS Backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "errlevel.h"
+#include "ssl_backend.h"
+#include "base64.h"
+#include "buffer.h"
+#include "misc.h"
+#include "manage.h"
+#include "ssl_common.h"
+
+#include <mbedtls/havege.h>
+
+#include "ssl_verify_mbedtls.h"
+#include <mbedtls/debug.h>
+#include <mbedtls/error.h>
+#include <mbedtls/version.h>
+
+#if MBEDTLS_VERSION_NUMBER >= 0x02040000
+    #include <mbedtls/net_sockets.h>
+#else
+    #include <mbedtls/net.h>
+#endif
+
+#include <mbedtls/oid.h>
+#include <mbedtls/pem.h>
+
+static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_legacy =
+{
+    /* Hashes from SHA-1 and above */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA1 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_RIPEMD160 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
+    0xFFFFFFF, /* Any PK alg    */
+    0xFFFFFFF, /* Any curve     */
+    1024,      /* RSA-1024 and larger */
+};
+
+static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_preferred =
+{
+    /* SHA-2 and above */
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 ) |
+    MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
+    0xFFFFFFF, /* Any PK alg    */
+    0xFFFFFFF, /* Any curve     */
+    2048,      /* RSA-2048 and larger */
+};
+
+#define openvpn_x509_crt_profile_suiteb mbedtls_x509_crt_profile_suiteb;
+
+void
+tls_init_lib(void)
+{
+}
+
+void
+tls_free_lib(void)
+{
+}
+
+void
+tls_clear_error(void)
+{
+}
+
+void
+tls_ctx_server_new(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+    CLEAR(*ctx);
+
+    ALLOC_OBJ_CLEAR(ctx->dhm_ctx, mbedtls_dhm_context);
+
+    ALLOC_OBJ_CLEAR(ctx->ca_chain, mbedtls_x509_crt);
+
+    ctx->endpoint = MBEDTLS_SSL_IS_SERVER;
+    ctx->initialised = true;
+}
+
+void
+tls_ctx_client_new(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+    CLEAR(*ctx);
+
+    ALLOC_OBJ_CLEAR(ctx->dhm_ctx, mbedtls_dhm_context);
+    ALLOC_OBJ_CLEAR(ctx->ca_chain, mbedtls_x509_crt);
+
+    ctx->endpoint = MBEDTLS_SSL_IS_CLIENT;
+    ctx->initialised = true;
+}
+
+void
+tls_ctx_free(struct tls_root_ctx *ctx)
+{
+    if (ctx)
+    {
+        mbedtls_pk_free(ctx->priv_key);
+        if (ctx->priv_key)
+        {
+            free(ctx->priv_key);
+        }
+
+        mbedtls_x509_crt_free(ctx->ca_chain);
+        if (ctx->ca_chain)
+        {
+            free(ctx->ca_chain);
+        }
+
+        mbedtls_x509_crt_free(ctx->crt_chain);
+        if (ctx->crt_chain)
+        {
+            free(ctx->crt_chain);
+        }
+
+        mbedtls_dhm_free(ctx->dhm_ctx);
+        if (ctx->dhm_ctx)
+        {
+            free(ctx->dhm_ctx);
+        }
+
+        mbedtls_x509_crl_free(ctx->crl);
+        if (ctx->crl)
+        {
+            free(ctx->crl);
+        }
+
+#if defined(ENABLE_PKCS11)
+        if (ctx->priv_key_pkcs11 != NULL)
+        {
+            mbedtls_pkcs11_priv_key_free(ctx->priv_key_pkcs11);
+            free(ctx->priv_key_pkcs11);
+        }
+#endif
+#if defined(MANAGMENT_EXTERNAL_KEY)
+        if (ctx->external_key != NULL)
+        {
+            free(ctx->external_key);
+        }
+#endif
+
+        if (ctx->allowed_ciphers)
+        {
+            free(ctx->allowed_ciphers);
+        }
+
+        CLEAR(*ctx);
+
+        ctx->initialised = false;
+
+    }
+}
+
+bool
+tls_ctx_initialised(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+    return ctx->initialised;
+}
+
+void
+key_state_export_keying_material(struct key_state_ssl *ssl,
+                                 struct tls_session *session)
+{
+}
+
+bool
+tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{
+    return true;
+}
+
+static const char *
+tls_translate_cipher_name(const char *cipher_name)
+{
+    const tls_cipher_name_pair *pair = tls_get_cipher_name_pair(cipher_name, strlen(cipher_name));
+
+    if (NULL == pair)
+    {
+        /* No translation found, return original */
+        return cipher_name;
+    }
+
+    if (0 != strcmp(cipher_name, pair->iana_name))
+    {
+        /* Deprecated name found, notify user */
+        msg(M_WARN, "Deprecated cipher suite name '%s', please use IANA name '%s'", pair->openssl_name, pair->iana_name);
+    }
+
+    return pair->iana_name;
+}
+
+void
+tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers)
+{
+    if (ciphers == NULL)
+    {
+        /* Nothing to do, return without warning message */
+        return;
+    }
+
+    msg(M_WARN, "mbed TLS does not support setting tls-ciphersuites. "
+                "Ignoring TLS 1.3 cipher list: %s", ciphers);
+}
+
+void
+tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
+{
+    char *tmp_ciphers, *tmp_ciphers_orig, *token;
+    int i, cipher_count;
+    int ciphers_len;
+
+    if (NULL == ciphers)
+    {
+        return; /* Nothing to do */
+
+    }
+    ciphers_len = strlen(ciphers);
+
+    ASSERT(NULL != ctx);
+    ASSERT(0 != ciphers_len);
+
+    /* Get number of ciphers */
+    for (i = 0, cipher_count = 1; i < ciphers_len; i++)
+    {
+        if (ciphers[i] == ':')
+        {
+            cipher_count++;
+        }
+    }
+
+    /* Allocate an array for them */
+    ALLOC_ARRAY_CLEAR(ctx->allowed_ciphers, int, cipher_count+1)
+
+    /* Parse allowed ciphers, getting IDs */
+    i = 0;
+    tmp_ciphers_orig = tmp_ciphers = string_alloc(ciphers, NULL);
+
+    token = strtok(tmp_ciphers, ":");
+    while (token)
+    {
+        ctx->allowed_ciphers[i] = mbedtls_ssl_get_ciphersuite_id(
+            tls_translate_cipher_name(token));
+        if (0 != ctx->allowed_ciphers[i])
+        {
+            i++;
+        }
+        token = strtok(NULL, ":");
+    }
+    free(tmp_ciphers_orig);
+}
+
+void
+tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile)
+{
+    if (!profile || 0 == strcmp(profile, "legacy"))
+    {
+        ctx->cert_profile = openvpn_x509_crt_profile_legacy;
+    }
+    else if (0 == strcmp(profile, "preferred"))
+    {
+        ctx->cert_profile = openvpn_x509_crt_profile_preferred;
+    }
+    else if (0 == strcmp(profile, "suiteb"))
+    {
+        ctx->cert_profile = openvpn_x509_crt_profile_suiteb;
+    }
+    else
+    {
+        msg (M_FATAL, "ERROR: Invalid cert profile: %s", profile);
+    }
+}
+
+void
+tls_ctx_check_cert_time(const struct tls_root_ctx *ctx)
+{
+    ASSERT(ctx);
+    if (ctx->crt_chain == NULL)
+    {
+        return; /* Nothing to check if there is no certificate */
+    }
+
+    if (mbedtls_x509_time_is_future(&ctx->crt_chain->valid_from))
+    {
+        msg(M_WARN, "WARNING: Your certificate is not yet valid!");
+    }
+
+    if (mbedtls_x509_time_is_past(&ctx->crt_chain->valid_to))
+    {
+        msg(M_WARN, "WARNING: Your certificate has expired!");
+    }
+}
+
+void
+tls_ctx_load_dh_params(struct tls_root_ctx *ctx, const char *dh_file,
+                       const char *dh_inline
+                       )
+{
+    if (!strcmp(dh_file, INLINE_FILE_TAG) && dh_inline)
+    {
+        if (!mbed_ok(mbedtls_dhm_parse_dhm(ctx->dhm_ctx,
+                                           (const unsigned char *) dh_inline, strlen(dh_inline)+1)))
+        {
+            msg(M_FATAL, "Cannot read inline DH parameters");
+        }
+    }
+    else
+    {
+        if (!mbed_ok(mbedtls_dhm_parse_dhmfile(ctx->dhm_ctx, dh_file)))
+        {
+            msg(M_FATAL, "Cannot read DH parameters from file %s", dh_file);
+        }
+    }
+
+    msg(D_TLS_DEBUG_LOW, "Diffie-Hellman initialized with " counter_format " bit key",
+        (counter_type) 8 * mbedtls_mpi_size(&ctx->dhm_ctx->P));
+}
+
+void
+tls_ctx_load_ecdh_params(struct tls_root_ctx *ctx, const char *curve_name
+                         )
+{
+    if (NULL != curve_name)
+    {
+        msg(M_WARN, "WARNING: mbed TLS builds do not support specifying an ECDH "
+            "curve, using default curves.");
+    }
+}
+
+int
+tls_ctx_load_pkcs12(struct tls_root_ctx *ctx, const char *pkcs12_file,
+                    const char *pkcs12_file_inline,
+                    bool load_ca_file
+                    )
+{
+    msg(M_FATAL, "PKCS #12 files not yet supported for mbed TLS.");
+    return 0;
+}
+
+#ifdef ENABLE_CRYPTOAPI
+void
+tls_ctx_load_cryptoapi(struct tls_root_ctx *ctx, const char *cryptoapi_cert)
+{
+    msg(M_FATAL, "Windows CryptoAPI not yet supported for mbed TLS.");
+}
+#endif /* _WIN32 */
+
+void
+tls_ctx_load_cert_file(struct tls_root_ctx *ctx, const char *cert_file,
+                       const char *cert_inline
+                       )
+{
+    ASSERT(NULL != ctx);
+
+    if (!ctx->crt_chain)
+    {
+        ALLOC_OBJ_CLEAR(ctx->crt_chain, mbedtls_x509_crt);
+    }
+
+    if (!strcmp(cert_file, INLINE_FILE_TAG) && cert_inline)
+    {
+        if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
+                                            (const unsigned char *) cert_inline, strlen(cert_inline)+1)))
+        {
+            msg(M_FATAL, "Cannot load inline certificate file");
+        }
+    }
+    else
+    {
+        if (!mbed_ok(mbedtls_x509_crt_parse_file(ctx->crt_chain, cert_file)))
+        {
+            msg(M_FATAL, "Cannot load certificate file %s", cert_file);
+        }
+    }
+}
+
+int
+tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const char *priv_key_file,
+                       const char *priv_key_inline
+                       )
+{
+    int status;
+    ASSERT(NULL != ctx);
+
+    if (!ctx->priv_key)
+    {
+        ALLOC_OBJ_CLEAR(ctx->priv_key, mbedtls_pk_context);
+    }
+
+    if (!strcmp(priv_key_file, INLINE_FILE_TAG) && priv_key_inline)
+    {
+        status = mbedtls_pk_parse_key(ctx->priv_key,
+                                      (const unsigned char *) priv_key_inline, strlen(priv_key_inline)+1,
+                                      NULL, 0);
+
+        if (MBEDTLS_ERR_PK_PASSWORD_REQUIRED == status)
+        {
+            char passbuf[512] = {0};
+            pem_password_callback(passbuf, 512, 0, NULL);
+            status = mbedtls_pk_parse_key(ctx->priv_key,
+                                          (const unsigned char *) priv_key_inline,
+                                          strlen(priv_key_inline)+1, (unsigned char *) passbuf,
+                                          strlen(passbuf));
+        }
+    }
+    else
+    {
+        status = mbedtls_pk_parse_keyfile(ctx->priv_key, priv_key_file, NULL);
+        if (MBEDTLS_ERR_PK_PASSWORD_REQUIRED == status)
+        {
+            char passbuf[512] = {0};
+            pem_password_callback(passbuf, 512, 0, NULL);
+            status = mbedtls_pk_parse_keyfile(ctx->priv_key, priv_key_file, passbuf);
+        }
+    }
+    if (!mbed_ok(status))
+    {
+#ifdef ENABLE_MANAGEMENT
+        if (management && (MBEDTLS_ERR_PK_PASSWORD_MISMATCH == status))
+        {
+            management_auth_failure(management, UP_TYPE_PRIVATE_KEY, NULL);
+        }
+#endif
+        msg(M_WARN, "Cannot load private key file %s", priv_key_file);
+        return 1;
+    }
+
+    if (!mbed_ok(mbedtls_pk_check_pair(&ctx->crt_chain->pk, ctx->priv_key)))
+    {
+        msg(M_WARN, "Private key does not match the certificate");
+        return 1;
+    }
+
+    return 0;
+}
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+
+struct external_context {
+    size_t signature_length;
+};
+
+/**
+ * external_pkcs1_sign implements a mbed TLS rsa_sign_func callback, that uses
+ * the management interface to request an RSA signature for the supplied hash.
+ *
+ * @param ctx_voidptr   Management external key context.
+ * @param f_rng         (Unused)
+ * @param p_rng         (Unused)
+ * @param mode          RSA mode (should be RSA_PRIVATE).
+ * @param md_alg        Message digest ('hash') algorithm type.
+ * @param hashlen       Length of hash (overridden by length specified by md_alg
+ *                      if md_alg != MBEDTLS_MD_NONE).
+ * @param hash          The digest ('hash') to sign. Should have a size
+ *                      matching the length of md_alg (if != MBEDTLS_MD_NONE),
+ *                      or hashlen otherwise.
+ * @param sig           Buffer that returns the signature. Should be at least of
+ *                      size ctx->signature_length.
+ *
+ * @return 0 on success, non-zero mbed TLS error code on failure.
+ */
+static inline int
+external_pkcs1_sign( void *ctx_voidptr,
+                     int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode,
+                     mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash,
+                     unsigned char *sig )
+{
+    struct external_context *const ctx = ctx_voidptr;
+    char *in_b64 = NULL;
+    char *out_b64 = NULL;
+    int rv;
+    unsigned char *p = sig;
+    size_t asn_len = 0, oid_size = 0, sig_len = 0;
+    const char *oid = NULL;
+
+    if (NULL == ctx)
+    {
+        return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+    }
+
+    if (MBEDTLS_RSA_PRIVATE != mode)
+    {
+        return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+    }
+
+    /*
+     * Support a wide range of hashes. TLSv1.1 and before only need SIG_RSA_RAW,
+     * but TLSv1.2 needs the full suite of hashes.
+     *
+     * This code has been taken from mbed TLS pkcs11_sign(), under the GPLv2.0+.
+     */
+    if (md_alg != MBEDTLS_MD_NONE)
+    {
+        const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
+        if (md_info == NULL)
+        {
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+        }
+
+        if (!mbed_ok(mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size )))
+        {
+            return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+        }
+
+        hashlen = mbedtls_md_get_size( md_info );
+        asn_len = 10 + oid_size;
+    }
+
+    sig_len = ctx->signature_length;
+    if ( (SIZE_MAX - hashlen) < asn_len || (hashlen + asn_len) > sig_len)
+    {
+        return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+    }
+
+    if (md_alg != MBEDTLS_MD_NONE)
+    {
+        /*
+         * DigestInfo ::= SEQUENCE {
+         *   digestAlgorithm DigestAlgorithmIdentifier,
+         *   digest Digest }
+         *
+         * DigestAlgorithmIdentifier ::= AlgorithmIdentifier
+         *
+         * Digest ::= OCTET STRING
+         */
+        *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+        *p++ = (unsigned char) ( 0x08 + oid_size + hashlen );
+        *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+        *p++ = (unsigned char) ( 0x04 + oid_size );
+        *p++ = MBEDTLS_ASN1_OID;
+        *p++ = oid_size & 0xFF;
+        memcpy( p, oid, oid_size );
+        p += oid_size;
+        *p++ = MBEDTLS_ASN1_NULL;
+        *p++ = 0x00;
+        *p++ = MBEDTLS_ASN1_OCTET_STRING;
+        *p++ = hashlen;
+
+        /* Determine added ASN length */
+        asn_len = p - sig;
+    }
+
+    /* Copy the hash to be signed */
+    memcpy( p, hash, hashlen );
+
+    /* convert 'from' to base64 */
+    if (openvpn_base64_encode(sig, asn_len + hashlen, &in_b64) <= 0)
+    {
+        rv = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+        goto done;
+    }
+
+    /* call MI for signature */
+    if (management)
+    {
+        out_b64 = management_query_rsa_sig(management, in_b64);
+    }
+    if (!out_b64)
+    {
+        rv = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
+        goto done;
+    }
+
+    /* decode base64 signature to binary and verify length */
+    if (openvpn_base64_decode(out_b64, sig, ctx->signature_length) !=
+        ctx->signature_length)
+    {
+        rv = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
+        goto done;
+    }
+
+    rv = 0;
+
+done:
+    if (in_b64)
+    {
+        free(in_b64);
+    }
+    if (out_b64)
+    {
+        free(out_b64);
+    }
+    return rv;
+}
+
+static inline size_t
+external_key_len(void *vctx)
+{
+    struct external_context *const ctx = vctx;
+
+    return ctx->signature_length;
+}
+
+int
+tls_ctx_use_external_private_key(struct tls_root_ctx *ctx,
+                                 const char *cert_file, const char *cert_file_inline)
+{
+    ASSERT(NULL != ctx);
+
+    tls_ctx_load_cert_file(ctx, cert_file, cert_file_inline);
+
+    if (ctx->crt_chain == NULL)
+    {
+        return 1;
+    }
+
+    ALLOC_OBJ_CLEAR(ctx->external_key, struct external_context);
+    ctx->external_key->signature_length = mbedtls_pk_get_len(&ctx->crt_chain->pk);
+
+    ALLOC_OBJ_CLEAR(ctx->priv_key, mbedtls_pk_context);
+    if (!mbed_ok(mbedtls_pk_setup_rsa_alt(ctx->priv_key, ctx->external_key,
+                                          NULL, external_pkcs1_sign, external_key_len)))
+    {
+        return 1;
+    }
+
+    return 0;
+}
+#endif /* ifdef MANAGMENT_EXTERNAL_KEY */
+
+void
+tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
+                const char *ca_inline, const char *ca_path, bool tls_server
+                )
+{
+    if (ca_path)
+    {
+        msg(M_FATAL, "ERROR: mbed TLS cannot handle the capath directive");
+    }
+
+    if (ca_file && !strcmp(ca_file, INLINE_FILE_TAG) && ca_inline)
+    {
+        if (!mbed_ok(mbedtls_x509_crt_parse(ctx->ca_chain,
+                                            (const unsigned char *) ca_inline, strlen(ca_inline)+1)))
+        {
+            msg(M_FATAL, "Cannot load inline CA certificates");
+        }
+    }
+    else
+    {
+        /* Load CA file for verifying peer supplied certificate */
+        if (!mbed_ok(mbedtls_x509_crt_parse_file(ctx->ca_chain, ca_file)))
+        {
+            msg(M_FATAL, "Cannot load CA certificate file %s", ca_file);
+        }
+    }
+}
+
+void
+tls_ctx_load_extra_certs(struct tls_root_ctx *ctx, const char *extra_certs_file,
+                         const char *extra_certs_inline
+                         )
+{
+    ASSERT(NULL != ctx);
+
+    if (!ctx->crt_chain)
+    {
+        ALLOC_OBJ_CLEAR(ctx->crt_chain, mbedtls_x509_crt);
+    }
+
+    if (!strcmp(extra_certs_file, INLINE_FILE_TAG) && extra_certs_inline)
+    {
+        if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
+                                            (const unsigned char *) extra_certs_inline,
+                                            strlen(extra_certs_inline)+1)))
+        {
+            msg(M_FATAL, "Cannot load inline extra-certs file");
+        }
+    }
+    else
+    {
+        if (!mbed_ok(mbedtls_x509_crt_parse_file(ctx->crt_chain, extra_certs_file)))
+        {
+            msg(M_FATAL, "Cannot load extra-certs file: %s", extra_certs_file);
+        }
+    }
+}
+
+/* **************************************
+ *
+ * Key-state specific functions
+ *
+ ***************************************/
+
+/*
+ * "Endless buffer"
+ */
+
+static inline void
+buf_free_entry(buffer_entry *entry)
+{
+    if (NULL != entry)
+    {
+        free(entry->data);
+        free(entry);
+    }
+}
+
+static void
+buf_free_entries(endless_buffer *buf)
+{
+    while (buf->first_block)
+    {
+        buffer_entry *cur_block = buf->first_block;
+        buf->first_block = cur_block->next_block;
+        buf_free_entry(cur_block);
+    }
+    buf->last_block = NULL;
+}
+
+static int
+endless_buf_read( endless_buffer *in, unsigned char *out, size_t out_len )
+{
+    size_t read_len = 0;
+
+    if (in->first_block == NULL)
+    {
+        return MBEDTLS_ERR_SSL_WANT_READ;
+    }
+
+    while (in->first_block != NULL && read_len < out_len)
+    {
+        int block_len = in->first_block->length - in->data_start;
+        if (block_len <= out_len - read_len)
+        {
+            buffer_entry *cur_entry = in->first_block;
+            memcpy(out + read_len, cur_entry->data + in->data_start,
+                   block_len);
+
+            read_len += block_len;
+
+            in->first_block = cur_entry->next_block;
+            in->data_start = 0;
+
+            if (in->first_block == NULL)
+            {
+                in->last_block = NULL;
+            }
+
+            buf_free_entry(cur_entry);
+        }
+        else
+        {
+            memcpy(out + read_len, in->first_block->data + in->data_start,
+                   out_len - read_len);
+            in->data_start += out_len - read_len;
+            read_len = out_len;
+        }
+    }
+
+    return read_len;
+}
+
+static int
+endless_buf_write( endless_buffer *out, const unsigned char *in, size_t len )
+{
+    buffer_entry *new_block = malloc(sizeof(buffer_entry));
+    if (NULL == new_block)
+    {
+        return MBEDTLS_ERR_NET_SEND_FAILED;
+    }
+
+    new_block->data = malloc(len);
+    if (NULL == new_block->data)
+    {
+        free(new_block);
+        return MBEDTLS_ERR_NET_SEND_FAILED;
+    }
+
+    new_block->length = len;
+    new_block->next_block = NULL;
+
+    memcpy(new_block->data, in, len);
+
+    if (NULL == out->first_block)
+    {
+        out->first_block = new_block;
+    }
+
+    if (NULL != out->last_block)
+    {
+        out->last_block->next_block = new_block;
+    }
+
+    out->last_block = new_block;
+
+    return len;
+}
+
+static int
+ssl_bio_read( void *ctx, unsigned char *out, size_t out_len)
+{
+    bio_ctx *my_ctx = (bio_ctx *) ctx;
+    return endless_buf_read(&my_ctx->in, out, out_len);
+}
+
+static int
+ssl_bio_write( void *ctx, const unsigned char *in, size_t in_len)
+{
+    bio_ctx *my_ctx = (bio_ctx *) ctx;
+    return endless_buf_write(&my_ctx->out, in, in_len);
+}
+
+static void
+my_debug( void *ctx, int level, const char *file, int line,
+          const char *str )
+{
+    int my_loglevel = (level < 3) ? D_TLS_DEBUG_MED : D_TLS_DEBUG;
+    msg(my_loglevel, "mbed TLS msg (%s:%d): %s", file, line, str);
+}
+
+/*
+ * Further personalise the RNG using a hash of the public key
+ */
+void
+tls_ctx_personalise_random(struct tls_root_ctx *ctx)
+{
+    static char old_sha256_hash[32] = {0};
+    unsigned char sha256_hash[32] = {0};
+    mbedtls_ctr_drbg_context *cd_ctx = rand_ctx_get();
+
+    if (NULL != ctx->crt_chain)
+    {
+        const md_kt_t *sha256_kt = md_kt_get("SHA256");
+        mbedtls_x509_crt *cert = ctx->crt_chain;
+
+        if (!md_full(sha256_kt, cert->tbs.p, cert->tbs.len, sha256_hash))
+        {
+            msg(M_WARN, "WARNING: failed to personalise random");
+        }
+
+        if (0 != memcmp(old_sha256_hash, sha256_hash, sizeof(sha256_hash)))
+        {
+            mbedtls_ctr_drbg_update(cd_ctx, sha256_hash, 32);
+            memcpy(old_sha256_hash, sha256_hash, sizeof(old_sha256_hash));
+        }
+    }
+}
+
+int
+tls_version_max(void)
+{
+#if defined(MBEDTLS_SSL_MAJOR_VERSION_3) && defined(MBEDTLS_SSL_MINOR_VERSION_3)
+    return TLS_VER_1_2;
+#elif defined(MBEDTLS_SSL_MAJOR_VERSION_3) && defined(MBEDTLS_SSL_MINOR_VERSION_2)
+    return TLS_VER_1_1;
+#else
+    return TLS_VER_1_0;
+#endif
+}
+
+/**
+ * Convert an OpenVPN tls-version variable to mbed TLS format (i.e. a major and
+ * minor ssl version number).
+ *
+ * @param tls_ver       The tls-version variable to convert.
+ * @param major         Returns the TLS major version in mbed TLS format.
+ *                      Must be a valid pointer.
+ * @param minor         Returns the TLS minor version in mbed TLS format.
+ *                      Must be a valid pointer.
+ */
+static void
+tls_version_to_major_minor(int tls_ver, int *major, int *minor)
+{
+    ASSERT(major);
+    ASSERT(minor);
+
+    switch (tls_ver)
+    {
+        case TLS_VER_1_0:
+            *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+            *minor = MBEDTLS_SSL_MINOR_VERSION_1;
+            break;
+
+        case TLS_VER_1_1:
+            *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+            *minor = MBEDTLS_SSL_MINOR_VERSION_2;
+            break;
+
+        case TLS_VER_1_2:
+            *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+            *minor = MBEDTLS_SSL_MINOR_VERSION_3;
+            break;
+
+        default:
+            msg(M_FATAL, "%s: invalid TLS version %d", __func__, tls_ver);
+            break;
+    }
+}
+
+void
+backend_tls_ctx_reload_crl(struct tls_root_ctx *ctx, const char *crl_file,
+                           const char *crl_inline)
+{
+    ASSERT(crl_file);
+
+    if (ctx->crl == NULL)
+    {
+        ALLOC_OBJ_CLEAR(ctx->crl, mbedtls_x509_crl);
+    }
+    mbedtls_x509_crl_free(ctx->crl);
+
+    if (!strcmp(crl_file, INLINE_FILE_TAG) && crl_inline)
+    {
+        if (!mbed_ok(mbedtls_x509_crl_parse(ctx->crl,
+                                            (const unsigned char *)crl_inline, strlen(crl_inline)+1)))
+        {
+            msg(M_WARN, "CRL: cannot parse inline CRL");
+            goto err;
+        }
+    }
+    else
+    {
+        if (!mbed_ok(mbedtls_x509_crl_parse_file(ctx->crl, crl_file)))
+        {
+            msg(M_WARN, "CRL: cannot read CRL from file %s", crl_file);
+            goto err;
+        }
+    }
+    return;
+
+err:
+    mbedtls_x509_crl_free(ctx->crl);
+}
+
+void
+key_state_ssl_init(struct key_state_ssl *ks_ssl,
+                   const struct tls_root_ctx *ssl_ctx, bool is_server, struct tls_session *session)
+{
+    ASSERT(NULL != ssl_ctx);
+    ASSERT(ks_ssl);
+    CLEAR(*ks_ssl);
+
+    /* Initialise SSL config */
+    ALLOC_OBJ_CLEAR(ks_ssl->ssl_config, mbedtls_ssl_config);
+    mbedtls_ssl_config_init(ks_ssl->ssl_config);
+    mbedtls_ssl_config_defaults(ks_ssl->ssl_config, ssl_ctx->endpoint,
+                                MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT);
+#ifdef MBEDTLS_DEBUG_C
+    mbedtls_debug_set_threshold(3);
+#endif
+    mbedtls_ssl_conf_dbg(ks_ssl->ssl_config, my_debug, NULL);
+    mbedtls_ssl_conf_rng(ks_ssl->ssl_config, mbedtls_ctr_drbg_random,
+                         rand_ctx_get());
+
+    mbedtls_ssl_conf_cert_profile(ks_ssl->ssl_config, &ssl_ctx->cert_profile);
+
+    if (ssl_ctx->allowed_ciphers)
+    {
+        mbedtls_ssl_conf_ciphersuites(ks_ssl->ssl_config, ssl_ctx->allowed_ciphers);
+    }
+
+    /* Disable record splitting (for now).  OpenVPN assumes records are sent
+     * unfragmented, and changing that will require thorough review and
+     * testing.  Since OpenVPN is not susceptible to BEAST, we can just
+     * disable record splitting as a quick fix. */
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+    mbedtls_ssl_conf_cbc_record_splitting(ks_ssl->ssl_config,
+                                          MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED);
+#endif /* MBEDTLS_SSL_CBC_RECORD_SPLITTING */
+
+    /* Initialise authentication information */
+    if (is_server)
+    {
+        mbed_ok(mbedtls_ssl_conf_dh_param_ctx(ks_ssl->ssl_config,
+                                              ssl_ctx->dhm_ctx));
+    }
+
+    mbed_ok(mbedtls_ssl_conf_own_cert(ks_ssl->ssl_config, ssl_ctx->crt_chain,
+                                      ssl_ctx->priv_key));
+
+    /* Initialise SSL verification */
+#if P2MP_SERVER
+    if (session->opt->ssl_flags & SSLF_CLIENT_CERT_OPTIONAL)
+    {
+        mbedtls_ssl_conf_authmode(ks_ssl->ssl_config, MBEDTLS_SSL_VERIFY_OPTIONAL);
+    }
+    else if (!(session->opt->ssl_flags & SSLF_CLIENT_CERT_NOT_REQUIRED))
+#endif
+    {
+        mbedtls_ssl_conf_authmode(ks_ssl->ssl_config, MBEDTLS_SSL_VERIFY_REQUIRED);
+    }
+    mbedtls_ssl_conf_verify(ks_ssl->ssl_config, verify_callback, session);
+
+    /* TODO: mbed TLS does not currently support sending the CA chain to the client */
+    mbedtls_ssl_conf_ca_chain(ks_ssl->ssl_config, ssl_ctx->ca_chain, ssl_ctx->crl);
+
+    /* Initialize minimum TLS version */
+    {
+        const int tls_version_min =
+            (session->opt->ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT)
+            &SSLF_TLS_VERSION_MIN_MASK;
+
+        /* default to TLS 1.0 */
+        int major = MBEDTLS_SSL_MAJOR_VERSION_3;
+        int minor = MBEDTLS_SSL_MINOR_VERSION_1;
+
+        if (tls_version_min > TLS_VER_UNSPEC)
+        {
+            tls_version_to_major_minor(tls_version_min, &major, &minor);
+        }
+
+        mbedtls_ssl_conf_min_version(ks_ssl->ssl_config, major, minor);
+    }
+
+    /* Initialize maximum TLS version */
+    {
+        const int tls_version_max =
+            (session->opt->ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT)
+            &SSLF_TLS_VERSION_MAX_MASK;
+
+        if (tls_version_max > TLS_VER_UNSPEC)
+        {
+            int major, minor;
+            tls_version_to_major_minor(tls_version_max, &major, &minor);
+            mbedtls_ssl_conf_max_version(ks_ssl->ssl_config, major, minor);
+        }
+    }
+
+    /* Initialise SSL context */
+    ALLOC_OBJ_CLEAR(ks_ssl->ctx, mbedtls_ssl_context);
+    mbedtls_ssl_init(ks_ssl->ctx);
+    mbedtls_ssl_setup(ks_ssl->ctx, ks_ssl->ssl_config);
+
+    /* Initialise BIOs */
+    ALLOC_OBJ_CLEAR(ks_ssl->bio_ctx, bio_ctx);
+    mbedtls_ssl_set_bio(ks_ssl->ctx, ks_ssl->bio_ctx, ssl_bio_write,
+                        ssl_bio_read, NULL);
+}
+
+void
+key_state_ssl_free(struct key_state_ssl *ks_ssl)
+{
+    if (ks_ssl)
+    {
+        if (ks_ssl->ctx)
+        {
+            mbedtls_ssl_free(ks_ssl->ctx);
+            free(ks_ssl->ctx);
+        }
+        if (ks_ssl->ssl_config)
+        {
+            mbedtls_ssl_config_free(ks_ssl->ssl_config);
+            free(ks_ssl->ssl_config);
+        }
+        if (ks_ssl->bio_ctx)
+        {
+            buf_free_entries(&ks_ssl->bio_ctx->in);
+            buf_free_entries(&ks_ssl->bio_ctx->out);
+            free(ks_ssl->bio_ctx);
+        }
+        CLEAR(*ks_ssl);
+    }
+}
+
+int
+key_state_write_plaintext(struct key_state_ssl *ks, struct buffer *buf)
+{
+    int retval = 0;
+
+    ASSERT(buf);
+
+    retval = key_state_write_plaintext_const(ks, BPTR(buf), BLEN(buf));
+
+    if (1 == retval)
+    {
+        memset(BPTR(buf), 0, BLEN(buf));  /* erase data just written */
+        buf->len = 0;
+    }
+
+    return retval;
+}
+
+int
+key_state_write_plaintext_const(struct key_state_ssl *ks, const uint8_t *data, int len)
+{
+    int retval = 0;
+    perf_push(PERF_BIO_WRITE_PLAINTEXT);
+
+    ASSERT(NULL != ks);
+    ASSERT(len >= 0);
+
+    if (0 == len)
+    {
+        perf_pop();
+        return 0;
+    }
+
+    ASSERT(data);
+
+    retval = mbedtls_ssl_write(ks->ctx, data, len);
+
+    if (retval < 0)
+    {
+        perf_pop();
+        if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+        {
+            return 0;
+        }
+        mbed_log_err(D_TLS_ERRORS, retval,
+                     "TLS ERROR: write tls_write_plaintext_const error");
+        return -1;
+    }
+
+    if (retval != len)
+    {
+        msg(D_TLS_ERRORS,
+            "TLS ERROR: write tls_write_plaintext_const incomplete %d/%d",
+            retval, len);
+        perf_pop();
+        return -1;
+    }
+
+    /* successful write */
+    dmsg(D_HANDSHAKE_VERBOSE, "write tls_write_plaintext_const %d bytes", retval);
+
+    perf_pop();
+    return 1;
+}
+
+int
+key_state_read_ciphertext(struct key_state_ssl *ks, struct buffer *buf,
+                          int maxlen)
+{
+    int retval = 0;
+    int len = 0;
+
+    perf_push(PERF_BIO_READ_CIPHERTEXT);
+
+    ASSERT(NULL != ks);
+    ASSERT(buf);
+    ASSERT(buf->len >= 0);
+
+    if (buf->len)
+    {
+        perf_pop();
+        return 0;
+    }
+
+    len = buf_forward_capacity(buf);
+    if (maxlen < len)
+    {
+        len = maxlen;
+    }
+
+    retval = endless_buf_read(&ks->bio_ctx->out, BPTR(buf), len);
+
+    /* Error during read, check for retry error */
+    if (retval < 0)
+    {
+        perf_pop();
+        if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+        {
+            return 0;
+        }
+        mbed_log_err(D_TLS_ERRORS, retval, "TLS_ERROR: read tls_read_ciphertext error");
+        buf->len = 0;
+        return -1;
+    }
+    /* Nothing read, try again */
+    if (0 == retval)
+    {
+        buf->len = 0;
+        perf_pop();
+        return 0;
+    }
+
+    /* successful read */
+    dmsg(D_HANDSHAKE_VERBOSE, "read tls_read_ciphertext %d bytes", retval);
+    buf->len = retval;
+    perf_pop();
+    return 1;
+}
+
+int
+key_state_write_ciphertext(struct key_state_ssl *ks, struct buffer *buf)
+{
+    int retval = 0;
+    perf_push(PERF_BIO_WRITE_CIPHERTEXT);
+
+    ASSERT(NULL != ks);
+    ASSERT(buf);
+    ASSERT(buf->len >= 0);
+
+    if (0 == buf->len)
+    {
+        perf_pop();
+        return 0;
+    }
+
+    retval = endless_buf_write(&ks->bio_ctx->in, BPTR(buf), buf->len);
+
+    if (retval < 0)
+    {
+        perf_pop();
+
+        if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+        {
+            return 0;
+        }
+        mbed_log_err(D_TLS_ERRORS, retval,
+                     "TLS ERROR: write tls_write_ciphertext error");
+        return -1;
+    }
+
+    if (retval != buf->len)
+    {
+        msg(D_TLS_ERRORS, "TLS ERROR: write tls_write_ciphertext incomplete %d/%d",
+            retval, buf->len);
+        perf_pop();
+        return -1;
+    }
+
+    /* successful write */
+    dmsg(D_HANDSHAKE_VERBOSE, "write tls_write_ciphertext %d bytes", retval);
+
+    memset(BPTR(buf), 0, BLEN(buf));  /* erase data just written */
+    buf->len = 0;
+
+    perf_pop();
+    return 1;
+}
+
+int
+key_state_read_plaintext(struct key_state_ssl *ks, struct buffer *buf,
+                         int maxlen)
+{
+    int retval = 0;
+    int len = 0;
+
+    perf_push(PERF_BIO_READ_PLAINTEXT);
+
+    ASSERT(NULL != ks);
+    ASSERT(buf);
+    ASSERT(buf->len >= 0);
+
+    if (buf->len)
+    {
+        perf_pop();
+        return 0;
+    }
+
+    len = buf_forward_capacity(buf);
+    if (maxlen < len)
+    {
+        len = maxlen;
+    }
+
+    retval = mbedtls_ssl_read(ks->ctx, BPTR(buf), len);
+
+    /* Error during read, check for retry error */
+    if (retval < 0)
+    {
+        if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+        {
+            return 0;
+        }
+        mbed_log_err(D_TLS_ERRORS, retval, "TLS_ERROR: read tls_read_plaintext error");
+        buf->len = 0;
+        perf_pop();
+        return -1;
+    }
+    /* Nothing read, try again */
+    if (0 == retval)
+    {
+        buf->len = 0;
+        perf_pop();
+        return 0;
+    }
+
+    /* successful read */
+    dmsg(D_HANDSHAKE_VERBOSE, "read tls_read_plaintext %d bytes", retval);
+    buf->len = retval;
+
+    perf_pop();
+    return 1;
+}
+
+/* **************************************
+ *
+ * Information functions
+ *
+ * Print information for the end user.
+ *
+ ***************************************/
+void
+print_details(struct key_state_ssl *ks_ssl, const char *prefix)
+{
+    const mbedtls_x509_crt *cert;
+    char s1[256];
+    char s2[256];
+
+    s1[0] = s2[0] = 0;
+    openvpn_snprintf(s1, sizeof(s1), "%s %s, cipher %s",
+                     prefix,
+                     mbedtls_ssl_get_version(ks_ssl->ctx),
+                     mbedtls_ssl_get_ciphersuite(ks_ssl->ctx));
+
+    cert = mbedtls_ssl_get_peer_cert(ks_ssl->ctx);
+    if (cert != NULL)
+    {
+        openvpn_snprintf(s2, sizeof(s2), ", %u bit key",
+                         (unsigned int) mbedtls_pk_get_bitlen(&cert->pk));
+    }
+
+    msg(D_HANDSHAKE, "%s%s", s1, s2);
+}
+
+void
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                bool tls13)
+{
+    if (tls13)
+    {
+        /* mbed TLS has no TLS 1.3 support currently */
+        return;
+    }
+    struct tls_root_ctx tls_ctx;
+    const int *ciphers = mbedtls_ssl_list_ciphersuites();
+
+    tls_ctx_server_new(&tls_ctx);
+    tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile);
+    tls_ctx_restrict_ciphers(&tls_ctx, cipher_list);
+
+    if (tls_ctx.allowed_ciphers)
+    {
+        ciphers = tls_ctx.allowed_ciphers;
+    }
+
+    while (*ciphers != 0)
+    {
+        printf("%s\n", mbedtls_ssl_get_ciphersuite_name(*ciphers));
+        ciphers++;
+    }
+    tls_ctx_free(&tls_ctx);
+}
+
+void
+show_available_curves(void)
+{
+    const mbedtls_ecp_curve_info *pcurve = mbedtls_ecp_curve_list();
+
+    if (NULL == pcurve)
+    {
+        msg(M_FATAL, "Cannot retrieve curve list from mbed TLS");
+    }
+
+    /* Print curve list */
+    printf("Available Elliptic curves, listed in order of preference:\n\n");
+    while (MBEDTLS_ECP_DP_NONE != pcurve->grp_id)
+    {
+        printf("%s\n", pcurve->name);
+        pcurve++;
+    }
+}
+
+void
+get_highest_preference_tls_cipher(char *buf, int size)
+{
+    const char *cipher_name;
+    const int *ciphers = mbedtls_ssl_list_ciphersuites();
+    if (*ciphers == 0)
+    {
+        msg(M_FATAL, "Cannot retrieve list of supported SSL ciphers.");
+    }
+
+    cipher_name = mbedtls_ssl_get_ciphersuite_name(*ciphers);
+    strncpynt(buf, cipher_name, size);
+}
+
+const char *
+get_ssl_library_version(void)
+{
+    static char mbedtls_version[30];
+    unsigned int pv = mbedtls_version_get_number();
+    sprintf( mbedtls_version, "mbed TLS %d.%d.%d",
+             (pv>>24)&0xff, (pv>>16)&0xff, (pv>>8)&0xff );
+    return mbedtls_version;
+}
+
+#endif /* defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS) */
diff --git a/src/openvpn/ssl_mbedtls.h b/src/openvpn/ssl_mbedtls.h
new file mode 100644
index 0000000..f99aba1
--- /dev/null
+++ b/src/openvpn/ssl_mbedtls.h
@@ -0,0 +1,95 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel mbed TLS Backend
+ */
+
+#ifndef SSL_MBEDTLS_H_
+#define SSL_MBEDTLS_H_
+
+#include "syshead.h"
+
+#include <mbedtls/ssl.h>
+#include <mbedtls/x509_crt.h>
+
+#if defined(ENABLE_PKCS11)
+#include <mbedtls/pkcs11.h>
+#endif
+
+typedef struct _buffer_entry buffer_entry;
+
+struct _buffer_entry {
+    size_t length;
+    uint8_t *data;
+    buffer_entry *next_block;
+};
+
+typedef struct {
+    size_t data_start;
+    buffer_entry *first_block;
+    buffer_entry *last_block;
+} endless_buffer;
+
+typedef struct {
+    endless_buffer in;
+    endless_buffer out;
+} bio_ctx;
+
+/**
+ * Structure that wraps the TLS context. Contents differ depending on the
+ * SSL library used.
+ *
+ * Either \c priv_key_pkcs11 or \c priv_key must be filled in.
+ */
+struct tls_root_ctx {
+    bool initialised;           /**< True if the context has been initialised */
+
+    int endpoint;               /**< Whether or not this is a server or a client */
+
+    mbedtls_dhm_context *dhm_ctx;       /**< Diffie-Helmann-Merkle context */
+    mbedtls_x509_crt *crt_chain;        /**< Local Certificate chain */
+    mbedtls_x509_crt *ca_chain;         /**< CA chain for remote verification */
+    mbedtls_pk_context *priv_key;       /**< Local private key */
+    mbedtls_x509_crl *crl;              /**< Certificate Revocation List */
+    time_t crl_last_mtime;              /**< CRL last modification time */
+    off_t crl_last_size;                /**< size of last loaded CRL */
+#if defined(ENABLE_PKCS11)
+    mbedtls_pkcs11_context *priv_key_pkcs11;    /**< PKCS11 private key */
+#endif
+#ifdef MANAGMENT_EXTERNAL_KEY
+    struct external_context *external_key; /**< Management external key */
+#endif
+    int *allowed_ciphers;       /**< List of allowed ciphers for this connection */
+    mbedtls_x509_crt_profile cert_profile; /**< Allowed certificate types */
+};
+
+struct key_state_ssl {
+    mbedtls_ssl_config *ssl_config;     /**< mbedTLS global ssl config */
+    mbedtls_ssl_context *ctx;           /**< mbedTLS connection context */
+    bio_ctx *bio_ctx;
+};
+
+
+#endif /* SSL_MBEDTLS_H_ */
diff --git a/src/openvpn/ssl_openssl.c b/src/openvpn/ssl_openssl.c
new file mode 100644
index 0000000..19509b7
--- /dev/null
+++ b/src/openvpn/ssl_openssl.c
@@ -0,0 +1,2014 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel OpenSSL Backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL)
+
+#include "errlevel.h"
+#include "buffer.h"
+#include "misc.h"
+#include "manage.h"
+#include "memdbg.h"
+#include "ssl_backend.h"
+#include "ssl_common.h"
+#include "base64.h"
+#include "openssl_compat.h"
+
+#ifdef ENABLE_CRYPTOAPI
+#include "cryptoapi.h"
+#endif
+
+#include "ssl_verify_openssl.h"
+
+#include <openssl/err.h>
+#include <openssl/pkcs12.h>
+#include <openssl/x509.h>
+#include <openssl/crypto.h>
+#ifndef OPENSSL_NO_EC
+#include <openssl/ec.h>
+#endif
+
+/*
+ * Allocate space in SSL objects in which to store a struct tls_session
+ * pointer back to parent.
+ *
+ */
+
+int mydata_index; /* GLOBAL */
+
+void
+tls_init_lib(void)
+{
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER))
+    SSL_library_init();
+#ifndef ENABLE_SMALL
+    SSL_load_error_strings();
+#endif
+    OpenSSL_add_all_algorithms();
+#endif
+    mydata_index = SSL_get_ex_new_index(0, "struct session *", NULL, NULL, NULL);
+    ASSERT(mydata_index >= 0);
+}
+
+void
+tls_free_lib(void)
+{
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER))
+    EVP_cleanup();
+#ifndef ENABLE_SMALL
+    ERR_free_strings();
+#endif
+#endif
+}
+
+void
+tls_clear_error(void)
+{
+    ERR_clear_error();
+}
+
+void
+tls_ctx_server_new(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+
+    ctx->ctx = SSL_CTX_new(SSLv23_server_method());
+
+    if (ctx->ctx == NULL)
+    {
+        crypto_msg(M_FATAL, "SSL_CTX_new SSLv23_server_method");
+    }
+}
+
+void
+tls_ctx_client_new(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+
+    ctx->ctx = SSL_CTX_new(SSLv23_client_method());
+
+    if (ctx->ctx == NULL)
+    {
+        crypto_msg(M_FATAL, "SSL_CTX_new SSLv23_client_method");
+    }
+}
+
+void
+tls_ctx_free(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+    if (NULL != ctx->ctx)
+    {
+        SSL_CTX_free(ctx->ctx);
+    }
+    ctx->ctx = NULL;
+}
+
+bool
+tls_ctx_initialised(struct tls_root_ctx *ctx)
+{
+    ASSERT(NULL != ctx);
+    return NULL != ctx->ctx;
+}
+
+void
+key_state_export_keying_material(struct key_state_ssl *ssl,
+                                 struct tls_session *session)
+{
+    if (session->opt->ekm_size > 0)
+    {
+#if (OPENSSL_VERSION_NUMBER >= 0x10001000)
+        unsigned int size = session->opt->ekm_size;
+        struct gc_arena gc = gc_new();
+        unsigned char *ekm = (unsigned char *) gc_malloc(size, true, &gc);
+
+        if (SSL_export_keying_material(ssl->ssl, ekm, size,
+                                       session->opt->ekm_label, session->opt->ekm_label_size, NULL, 0, 0))
+        {
+            unsigned int len = (size * 2) + 2;
+
+            const char *key = format_hex_ex(ekm, size, len, 0, NULL, &gc);
+            setenv_str(session->opt->es, "exported_keying_material", key);
+
+            dmsg(D_TLS_DEBUG_MED, "%s: exported keying material: %s",
+                 __func__, key);
+        }
+        else
+        {
+            msg(M_WARN, "WARNING: Export keying material failed!");
+            setenv_del(session->opt->es, "exported_keying_material");
+        }
+        gc_free(&gc);
+#endif /* if (OPENSSL_VERSION_NUMBER >= 0x10001000) */
+    }
+}
+
+/*
+ * Print debugging information on SSL/TLS session negotiation.
+ */
+
+#ifndef INFO_CALLBACK_SSL_CONST
+#define INFO_CALLBACK_SSL_CONST const
+#endif
+static void
+info_callback(INFO_CALLBACK_SSL_CONST SSL *s, int where, int ret)
+{
+    if (where & SSL_CB_LOOP)
+    {
+        dmsg(D_HANDSHAKE_VERBOSE, "SSL state (%s): %s",
+             where & SSL_ST_CONNECT ? "connect" :
+             where &SSL_ST_ACCEPT ? "accept" :
+             "undefined", SSL_state_string_long(s));
+    }
+    else if (where & SSL_CB_ALERT)
+    {
+        dmsg(D_HANDSHAKE_VERBOSE, "SSL alert (%s): %s: %s",
+             where & SSL_CB_READ ? "read" : "write",
+             SSL_alert_type_string_long(ret),
+             SSL_alert_desc_string_long(ret));
+    }
+}
+
+/*
+ * Return maximum TLS version supported by local OpenSSL library.
+ * Assume that presence of SSL_OP_NO_TLSvX macro indicates that
+ * TLSvX is supported.
+ */
+int
+tls_version_max(void)
+{
+#if defined(TLS1_3_VERSION) && !defined(OPENSSL_NO_TLS1_3)
+    return TLS_VER_1_3;
+#elif defined(TLS1_2_VERSION) || defined(SSL_OP_NO_TLSv1_2)
+    return TLS_VER_1_2;
+#elif defined(TLS1_1_VERSION) || defined(SSL_OP_NO_TLSv1_1)
+    return TLS_VER_1_1;
+#else
+    return TLS_VER_1_0;
+#endif
+}
+
+/** Convert internal version number to openssl version number */
+static int
+openssl_tls_version(int ver)
+{
+    if (ver == TLS_VER_1_0)
+    {
+        return TLS1_VERSION;
+    }
+    else if (ver == TLS_VER_1_1)
+    {
+        return TLS1_1_VERSION;
+    }
+    else if (ver == TLS_VER_1_2)
+    {
+        return TLS1_2_VERSION;
+    }
+#if defined(TLS1_3_VERSION) && !defined(OPENSSL_NO_TLS1_3)
+    else if (ver == TLS_VER_1_3)
+    {
+        return TLS1_3_VERSION;
+    }
+#endif
+    return 0;
+}
+
+static bool
+tls_ctx_set_tls_versions(struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{
+    int tls_ver_min = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) & SSLF_TLS_VERSION_MIN_MASK);
+    int tls_ver_max = openssl_tls_version(
+        (ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) & SSLF_TLS_VERSION_MAX_MASK);
+
+    if (!tls_ver_min)
+    {
+        /* Enforce at least TLS 1.0 */
+        int cur_min = SSL_CTX_get_min_proto_version(ctx->ctx);
+        tls_ver_min = cur_min < TLS1_VERSION ? TLS1_VERSION : cur_min;
+    }
+
+    if (!SSL_CTX_set_min_proto_version(ctx->ctx, tls_ver_min))
+    {
+        msg(D_TLS_ERRORS, "%s: failed to set minimum TLS version", __func__);
+        return false;
+    }
+
+    if (tls_ver_max && !SSL_CTX_set_max_proto_version(ctx->ctx, tls_ver_max))
+    {
+        msg(D_TLS_ERRORS, "%s: failed to set maximum TLS version", __func__);
+        return false;
+    }
+
+    return true;
+}
+
+bool
+tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{
+    ASSERT(NULL != ctx);
+
+    /* default certificate verification flags */
+    int flags = SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
+
+    /* process SSL options */
+    long sslopt = SSL_OP_SINGLE_DH_USE | SSL_OP_NO_TICKET;
+#ifdef SSL_OP_CIPHER_SERVER_PREFERENCE
+    sslopt |= SSL_OP_CIPHER_SERVER_PREFERENCE;
+#endif
+#ifdef SSL_OP_NO_COMPRESSION
+    /* Disable compression - flag not available in OpenSSL 0.9.8 */
+    sslopt |= SSL_OP_NO_COMPRESSION;
+#endif
+
+    SSL_CTX_set_options(ctx->ctx, sslopt);
+
+    if (!tls_ctx_set_tls_versions(ctx, ssl_flags))
+    {
+        return false;
+    }
+
+#ifdef SSL_MODE_RELEASE_BUFFERS
+    SSL_CTX_set_mode(ctx->ctx, SSL_MODE_RELEASE_BUFFERS);
+#endif
+    SSL_CTX_set_session_cache_mode(ctx->ctx, SSL_SESS_CACHE_OFF);
+    SSL_CTX_set_default_passwd_cb(ctx->ctx, pem_password_callback);
+
+    /* Require peer certificate verification */
+#if P2MP_SERVER
+    if (ssl_flags & SSLF_CLIENT_CERT_NOT_REQUIRED)
+    {
+        flags = 0;
+    }
+    else if (ssl_flags & SSLF_CLIENT_CERT_OPTIONAL)
+    {
+        flags = SSL_VERIFY_PEER;
+    }
+#endif
+    SSL_CTX_set_verify(ctx->ctx, flags, verify_callback);
+
+    SSL_CTX_set_info_callback(ctx->ctx, info_callback);
+
+    return true;
+}
+
+void
+tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
+{
+    if (ciphers == NULL)
+    {
+        /* Use sane default TLS cipher list */
+        if (!SSL_CTX_set_cipher_list(ctx->ctx,
+                                     /* Use openssl's default list as a basis */
+                                     "DEFAULT"
+                                     /* Disable export ciphers and openssl's 'low' and 'medium' ciphers */
+                                     ":!EXP:!LOW:!MEDIUM"
+                                     /* Disable static (EC)DH keys (no forward secrecy) */
+                                     ":!kDH:!kECDH"
+                                     /* Disable DSA private keys */
+                                     ":!DSS"
+                                     /* Disable unsupported TLS modes */
+                                     ":!PSK:!SRP:!kRSA"))
+        {
+            crypto_msg(M_FATAL, "Failed to set default TLS cipher list.");
+        }
+        return;
+    }
+
+    /* Parse supplied cipher list and pass on to OpenSSL */
+    size_t begin_of_cipher, end_of_cipher;
+
+    const char *current_cipher;
+    size_t current_cipher_len;
+
+    const tls_cipher_name_pair *cipher_pair;
+
+    char openssl_ciphers[4096];
+    size_t openssl_ciphers_len = 0;
+    openssl_ciphers[0] = '\0';
+
+    ASSERT(NULL != ctx);
+
+    /* Translate IANA cipher suite names to OpenSSL names */
+    begin_of_cipher = end_of_cipher = 0;
+    for (; begin_of_cipher < strlen(ciphers); begin_of_cipher = end_of_cipher)
+    {
+        end_of_cipher += strcspn(&ciphers[begin_of_cipher], ":");
+        cipher_pair = tls_get_cipher_name_pair(&ciphers[begin_of_cipher], end_of_cipher - begin_of_cipher);
+
+        if (NULL == cipher_pair)
+        {
+            /* No translation found, use original */
+            current_cipher = &ciphers[begin_of_cipher];
+            current_cipher_len = end_of_cipher - begin_of_cipher;
+
+            /* Issue warning on missing translation */
+            /* %.*s format specifier expects length of type int, so guarantee */
+            /* that length is small enough and cast to int. */
+            msg(D_LOW, "No valid translation found for TLS cipher '%.*s'",
+                constrain_int(current_cipher_len, 0, 256), current_cipher);
+        }
+        else
+        {
+            /* Use OpenSSL name */
+            current_cipher = cipher_pair->openssl_name;
+            current_cipher_len = strlen(current_cipher);
+
+            if (end_of_cipher - begin_of_cipher == current_cipher_len
+                && 0 != memcmp(&ciphers[begin_of_cipher], cipher_pair->iana_name,
+                               end_of_cipher - begin_of_cipher))
+            {
+                /* Non-IANA name used, show warning */
+                msg(M_WARN, "Deprecated TLS cipher name '%s', please use IANA name '%s'", cipher_pair->openssl_name, cipher_pair->iana_name);
+            }
+        }
+
+        /* Make sure new cipher name fits in cipher string */
+        if ((SIZE_MAX - openssl_ciphers_len) < current_cipher_len
+            || ((sizeof(openssl_ciphers)-1) < openssl_ciphers_len + current_cipher_len))
+        {
+            msg(M_FATAL,
+                "Failed to set restricted TLS cipher list, too long (>%d).",
+                (int)sizeof(openssl_ciphers)-1);
+        }
+
+        /* Concatenate cipher name to OpenSSL cipher string */
+        memcpy(&openssl_ciphers[openssl_ciphers_len], current_cipher, current_cipher_len);
+        openssl_ciphers_len += current_cipher_len;
+        openssl_ciphers[openssl_ciphers_len] = ':';
+        openssl_ciphers_len++;
+
+        end_of_cipher++;
+    }
+
+    if (openssl_ciphers_len > 0)
+    {
+        openssl_ciphers[openssl_ciphers_len-1] = '\0';
+    }
+
+    /* Set OpenSSL cipher list */
+    if (!SSL_CTX_set_cipher_list(ctx->ctx, openssl_ciphers))
+    {
+        crypto_msg(M_FATAL, "Failed to set restricted TLS cipher list: %s", openssl_ciphers);
+    }
+}
+
+void
+convert_tls13_list_to_openssl(char *openssl_ciphers, size_t len,
+                              const char *ciphers)
+{
+    /*
+     * OpenSSL (and official IANA) cipher names have _ in them. We
+     * historically used names with - in them. Silently convert names
+     * with - to names with _ to support both
+     */
+    if (strlen(ciphers) >= (len - 1))
+    {
+        msg(M_FATAL,
+            "Failed to set restricted TLS 1.3 cipher list, too long (>%d).",
+            (int) (len - 1));
+    }
+
+    strncpy(openssl_ciphers, ciphers, len);
+
+    for (size_t i = 0; i < strlen(openssl_ciphers); i++)
+    {
+        if (openssl_ciphers[i] == '-')
+        {
+            openssl_ciphers[i] = '_';
+        }
+    }
+}
+
+void
+tls_ctx_restrict_ciphers_tls13(struct tls_root_ctx *ctx, const char *ciphers)
+{
+    if (ciphers == NULL)
+    {
+        /* default cipher list of OpenSSL 1.1.1 is sane, do not set own
+         * default as we do with tls-cipher */
+        return;
+    }
+
+#if (OPENSSL_VERSION_NUMBER < 0x1010100fL) || !defined(TLS1_3_VERSION) || defined(OPENSSL_NO_TLS1_3)
+        crypto_msg(M_WARN, "Not compiled with OpenSSL 1.1.1 or higher, or without TLS 1.3 support. "
+                       "Ignoring TLS 1.3 only tls-ciphersuites '%s' setting.",
+                        ciphers);
+#else
+    ASSERT(NULL != ctx);
+
+    char openssl_ciphers[4096];
+    convert_tls13_list_to_openssl(openssl_ciphers, sizeof(openssl_ciphers),
+                                  ciphers);
+
+    if (!SSL_CTX_set_ciphersuites(ctx->ctx, openssl_ciphers))
+    {
+        crypto_msg(M_FATAL, "Failed to set restricted TLS 1.3 cipher list: %s",
+                   openssl_ciphers);
+    }
+#endif
+}
+
+void
+tls_ctx_set_cert_profile(struct tls_root_ctx *ctx, const char *profile)
+{
+#ifdef HAVE_SSL_CTX_SET_SECURITY_LEVEL
+    /* OpenSSL does not have certificate profiles, but a complex set of
+     * callbacks that we could try to implement to achieve something similar.
+     * For now, use OpenSSL's security levels to achieve similar (but not equal)
+     * behaviour. */
+    if (!profile || 0 == strcmp(profile, "legacy"))
+    {
+        SSL_CTX_set_security_level(ctx->ctx, 1);
+    }
+    else if (0 == strcmp(profile, "preferred"))
+    {
+        SSL_CTX_set_security_level(ctx->ctx, 2);
+    }
+    else if (0 == strcmp(profile, "suiteb"))
+    {
+        SSL_CTX_set_security_level(ctx->ctx, 3);
+        SSL_CTX_set_cipher_list(ctx->ctx, "SUITEB128");
+    }
+    else
+    {
+        msg(M_FATAL, "ERROR: Invalid cert profile: %s", profile);
+    }
+#else
+    if (profile)
+    {
+        msg(M_WARN, "WARNING: OpenSSL 1.0.1 does not support --tls-cert-profile"
+            ", ignoring user-set profile: '%s'", profile);
+    }
+#endif
+}
+
+void
+tls_ctx_check_cert_time(const struct tls_root_ctx *ctx)
+{
+    int ret;
+    const X509 *cert;
+
+    ASSERT(ctx);
+
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(LIBRESSL_VERSION_NUMBER)
+    /* OpenSSL 1.0.2 and up */
+    cert = SSL_CTX_get0_certificate(ctx->ctx);
+#else
+    /* OpenSSL 1.0.1 and earlier need an SSL object to get at the certificate */
+    SSL *ssl = SSL_new(ctx->ctx);
+    cert = SSL_get_certificate(ssl);
+#endif
+
+    if (cert == NULL)
+    {
+        goto cleanup; /* Nothing to check if there is no certificate */
+    }
+
+    ret = X509_cmp_time(X509_get0_notBefore(cert), NULL);
+    if (ret == 0)
+    {
+        msg(D_TLS_DEBUG_MED, "Failed to read certificate notBefore field.");
+    }
+    if (ret > 0)
+    {
+        msg(M_WARN, "WARNING: Your certificate is not yet valid!");
+    }
+
+    ret = X509_cmp_time(X509_get0_notAfter(cert), NULL);
+    if (ret == 0)
+    {
+        msg(D_TLS_DEBUG_MED, "Failed to read certificate notAfter field.");
+    }
+    if (ret < 0)
+    {
+        msg(M_WARN, "WARNING: Your certificate has expired!");
+    }
+
+cleanup:
+#if OPENSSL_VERSION_NUMBER < 0x10002000L || defined(LIBRESSL_VERSION_NUMBER)
+    SSL_free(ssl);
+#endif
+    return;
+}
+
+void
+tls_ctx_load_dh_params(struct tls_root_ctx *ctx, const char *dh_file,
+                       const char *dh_file_inline
+                       )
+{
+    DH *dh;
+    BIO *bio;
+
+    ASSERT(NULL != ctx);
+
+    if (!strcmp(dh_file, INLINE_FILE_TAG) && dh_file_inline)
+    {
+        if (!(bio = BIO_new_mem_buf((char *)dh_file_inline, -1)))
+        {
+            crypto_msg(M_FATAL, "Cannot open memory BIO for inline DH parameters");
+        }
+    }
+    else
+    {
+        /* Get Diffie Hellman Parameters */
+        if (!(bio = BIO_new_file(dh_file, "r")))
+        {
+            crypto_msg(M_FATAL, "Cannot open %s for DH parameters", dh_file);
+        }
+    }
+
+    dh = PEM_read_bio_DHparams(bio, NULL, NULL, NULL);
+    BIO_free(bio);
+
+    if (!dh)
+    {
+        crypto_msg(M_FATAL, "Cannot load DH parameters from %s", dh_file);
+    }
+    if (!SSL_CTX_set_tmp_dh(ctx->ctx, dh))
+    {
+        crypto_msg(M_FATAL, "SSL_CTX_set_tmp_dh");
+    }
+
+    msg(D_TLS_DEBUG_LOW, "Diffie-Hellman initialized with %d bit key",
+        8 * DH_size(dh));
+
+    DH_free(dh);
+}
+
+void
+tls_ctx_load_ecdh_params(struct tls_root_ctx *ctx, const char *curve_name
+                         )
+{
+#ifndef OPENSSL_NO_EC
+    int nid = NID_undef;
+    EC_KEY *ecdh = NULL;
+    const char *sname = NULL;
+
+    /* Generate a new ECDH key for each SSL session (for non-ephemeral ECDH) */
+    SSL_CTX_set_options(ctx->ctx, SSL_OP_SINGLE_ECDH_USE);
+
+    if (curve_name != NULL)
+    {
+        /* Use user supplied curve if given */
+        msg(D_TLS_DEBUG, "Using user specified ECDH curve (%s)", curve_name);
+        nid = OBJ_sn2nid(curve_name);
+    }
+    else
+    {
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L
+#if (OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(LIBRESSL_VERSION_NUMBER))
+
+        /* OpenSSL 1.0.2 and newer can automatically handle ECDH parameter
+         * loading */
+        SSL_CTX_set_ecdh_auto(ctx->ctx, 1);
+
+        /* OpenSSL 1.1.0 and newer have always ecdh auto loading enabled,
+         * so do nothing */
+#endif
+        return;
+#else
+        /* For older OpenSSL we have to extract the curve from key on our own */
+        EC_KEY *eckey = NULL;
+        const EC_GROUP *ecgrp = NULL;
+        EVP_PKEY *pkey = NULL;
+
+        /* Little hack to get private key ref from SSL_CTX, yay OpenSSL... */
+        SSL *ssl = SSL_new(ctx->ctx);
+        if (!ssl)
+        {
+            crypto_msg(M_FATAL, "SSL_new failed");
+        }
+        pkey = SSL_get_privatekey(ssl);
+        SSL_free(ssl);
+
+        msg(D_TLS_DEBUG, "Extracting ECDH curve from private key");
+
+        if (pkey != NULL && (eckey = EVP_PKEY_get1_EC_KEY(pkey)) != NULL
+            && (ecgrp = EC_KEY_get0_group(eckey)) != NULL)
+        {
+            nid = EC_GROUP_get_curve_name(ecgrp);
+        }
+#endif
+    }
+
+    /* Translate NID back to name , just for kicks */
+    sname = OBJ_nid2sn(nid);
+    if (sname == NULL)
+    {
+        sname = "(Unknown)";
+    }
+
+    /* Create new EC key and set as ECDH key */
+    if (NID_undef == nid || NULL == (ecdh = EC_KEY_new_by_curve_name(nid)))
+    {
+        /* Creating key failed, fall back on sane default */
+        ecdh = EC_KEY_new_by_curve_name(NID_secp384r1);
+        const char *source = (NULL == curve_name) ?
+                             "extract curve from certificate" : "use supplied curve";
+        msg(D_TLS_DEBUG_LOW,
+            "Failed to %s (%s), using secp384r1 instead.", source, sname);
+        sname = OBJ_nid2sn(NID_secp384r1);
+    }
+
+    if (!SSL_CTX_set_tmp_ecdh(ctx->ctx, ecdh))
+    {
+        crypto_msg(M_FATAL, "SSL_CTX_set_tmp_ecdh: cannot add curve");
+    }
+
+    msg(D_TLS_DEBUG_LOW, "ECDH curve %s added", sname);
+
+    EC_KEY_free(ecdh);
+#else  /* ifndef OPENSSL_NO_EC */
+    msg(D_LOW, "Your OpenSSL library was built without elliptic curve support."
+        " Skipping ECDH parameter loading.");
+#endif /* OPENSSL_NO_EC */
+}
+
+int
+tls_ctx_load_pkcs12(struct tls_root_ctx *ctx, const char *pkcs12_file,
+                    const char *pkcs12_file_inline,
+                    bool load_ca_file
+                    )
+{
+    FILE *fp;
+    EVP_PKEY *pkey;
+    X509 *cert;
+    STACK_OF(X509) *ca = NULL;
+    PKCS12 *p12;
+    int i;
+    char password[256];
+
+    ASSERT(NULL != ctx);
+
+    if (!strcmp(pkcs12_file, INLINE_FILE_TAG) && pkcs12_file_inline)
+    {
+        BIO *b64 = BIO_new(BIO_f_base64());
+        BIO *bio = BIO_new_mem_buf((void *) pkcs12_file_inline,
+                                   (int) strlen(pkcs12_file_inline));
+        ASSERT(b64 && bio);
+        BIO_push(b64, bio);
+        p12 = d2i_PKCS12_bio(b64, NULL);
+        if (!p12)
+        {
+            crypto_msg(M_FATAL, "Error reading inline PKCS#12 file");
+        }
+        BIO_free(b64);
+        BIO_free(bio);
+    }
+    else
+    {
+        /* Load the PKCS #12 file */
+        if (!(fp = platform_fopen(pkcs12_file, "rb")))
+        {
+            crypto_msg(M_FATAL, "Error opening file %s", pkcs12_file);
+        }
+        p12 = d2i_PKCS12_fp(fp, NULL);
+        fclose(fp);
+        if (!p12)
+        {
+            crypto_msg(M_FATAL, "Error reading PKCS#12 file %s", pkcs12_file);
+        }
+    }
+
+    /* Parse the PKCS #12 file */
+    if (!PKCS12_parse(p12, "", &pkey, &cert, &ca))
+    {
+        pem_password_callback(password, sizeof(password) - 1, 0, NULL);
+        /* Reparse the PKCS #12 file with password */
+        ca = NULL;
+        if (!PKCS12_parse(p12, password, &pkey, &cert, &ca))
+        {
+#ifdef ENABLE_MANAGEMENT
+            if (management && (ERR_GET_REASON(ERR_peek_error()) == PKCS12_R_MAC_VERIFY_FAILURE))
+            {
+                management_auth_failure(management, UP_TYPE_PRIVATE_KEY, NULL);
+            }
+#endif
+            PKCS12_free(p12);
+            return 1;
+        }
+    }
+    PKCS12_free(p12);
+
+    /* Load Certificate */
+    if (!SSL_CTX_use_certificate(ctx->ctx, cert))
+    {
+        crypto_msg(M_FATAL, "Cannot use certificate");
+    }
+
+    /* Load Private Key */
+    if (!SSL_CTX_use_PrivateKey(ctx->ctx, pkey))
+    {
+        crypto_msg(M_FATAL, "Cannot use private key");
+    }
+
+    /* Check Private Key */
+    if (!SSL_CTX_check_private_key(ctx->ctx))
+    {
+        crypto_msg(M_FATAL, "Private key does not match the certificate");
+    }
+
+    /* Set Certificate Verification chain */
+    if (load_ca_file)
+    {
+        /* Add CAs from PKCS12 to the cert store and mark them as trusted.
+         * They're also used to fill in the chain of intermediate certs as
+         * necessary.
+         */
+        if (ca && sk_X509_num(ca))
+        {
+            for (i = 0; i < sk_X509_num(ca); i++)
+            {
+                X509_STORE *cert_store = SSL_CTX_get_cert_store(ctx->ctx);
+                if (!X509_STORE_add_cert(cert_store,sk_X509_value(ca, i)))
+                {
+                    crypto_msg(M_FATAL,"Cannot add certificate to certificate chain (X509_STORE_add_cert)");
+                }
+                if (!SSL_CTX_add_client_CA(ctx->ctx, sk_X509_value(ca, i)))
+                {
+                    crypto_msg(M_FATAL,"Cannot add certificate to client CA list (SSL_CTX_add_client_CA)");
+                }
+            }
+        }
+    }
+    else
+    {
+        /* If trusted CA certs were loaded from a PEM file, and we ignore the
+         * ones in PKCS12, do load PKCS12-provided certs to the client extra
+         * certs chain just in case they include intermediate CAs needed to
+         * prove my identity to the other end. This does not make them trusted.
+         */
+        if (ca && sk_X509_num(ca))
+        {
+            for (i = 0; i < sk_X509_num(ca); i++)
+            {
+                if (!SSL_CTX_add_extra_chain_cert(ctx->ctx,sk_X509_value(ca, i)))
+                {
+                    crypto_msg(M_FATAL, "Cannot add extra certificate to chain (SSL_CTX_add_extra_chain_cert)");
+                }
+            }
+        }
+    }
+    return 0;
+}
+
+#ifdef ENABLE_CRYPTOAPI
+void
+tls_ctx_load_cryptoapi(struct tls_root_ctx *ctx, const char *cryptoapi_cert)
+{
+    ASSERT(NULL != ctx);
+
+    /* Load Certificate and Private Key */
+    if (!SSL_CTX_use_CryptoAPI_certificate(ctx->ctx, cryptoapi_cert))
+    {
+        crypto_msg(M_FATAL, "Cannot load certificate \"%s\" from Microsoft Certificate Store", cryptoapi_cert);
+    }
+}
+#endif /* ENABLE_CRYPTOAPI */
+
+static void
+tls_ctx_add_extra_certs(struct tls_root_ctx *ctx, BIO *bio, bool optional)
+{
+    X509 *cert;
+    while (true)
+    {
+        cert = NULL;
+        if (!PEM_read_bio_X509(bio, &cert, NULL, NULL))
+        {
+            /*  a PEM_R_NO_START_LINE "Error" indicates that no certificate
+             *  is found in the buffer.  If loading more certificates is
+             *  optional, break without raising an error
+             */
+            if (optional
+                && ERR_GET_REASON(ERR_peek_error()) == PEM_R_NO_START_LINE)
+            {
+                /* remove that error from error stack */
+                (void)ERR_get_error();
+                break;
+            }
+
+            /* Otherwise, bail out with error */
+            crypto_msg(M_FATAL, "Error reading extra certificate");
+        }
+        /* takes ownership of cert like a set1 method */
+        if (SSL_CTX_add_extra_chain_cert(ctx->ctx, cert) != 1)
+        {
+            crypto_msg(M_FATAL, "Error adding extra certificate");
+        }
+        /* We loaded at least one certificate, so loading more is optional */
+        optional = true;
+    }
+}
+
+/* Like tls_ctx_load_cert, but returns a copy of the certificate in **X509 */
+static void
+tls_ctx_load_cert_file_and_copy(struct tls_root_ctx *ctx,
+                                const char *cert_file, const char *cert_file_inline, X509 **x509
+                                )
+{
+    BIO *in = NULL;
+    X509 *x = NULL;
+    int ret = 0;
+    bool inline_file = false;
+
+    ASSERT(NULL != ctx);
+    if (NULL != x509)
+    {
+        ASSERT(NULL == *x509);
+    }
+
+    inline_file = (strcmp(cert_file, INLINE_FILE_TAG) == 0);
+
+    if (inline_file && cert_file_inline)
+    {
+        in = BIO_new_mem_buf((char *)cert_file_inline, -1);
+    }
+    else
+    {
+        in = BIO_new_file(cert_file, "r");
+    }
+
+    if (in == NULL)
+    {
+        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_SYS_LIB);
+        goto end;
+    }
+
+    x = PEM_read_bio_X509(in, NULL,
+                          SSL_CTX_get_default_passwd_cb(ctx->ctx),
+                          SSL_CTX_get_default_passwd_cb_userdata(ctx->ctx));
+    if (x == NULL)
+    {
+        SSLerr(SSL_F_SSL_CTX_USE_CERTIFICATE_FILE, ERR_R_PEM_LIB);
+        goto end;
+    }
+
+    ret = SSL_CTX_use_certificate(ctx->ctx, x);
+    if (ret)
+    {
+        tls_ctx_add_extra_certs(ctx, in, true);
+    }
+
+end:
+    if (!ret)
+    {
+        if (inline_file)
+        {
+            crypto_msg(M_FATAL, "Cannot load inline certificate file");
+        }
+        else
+        {
+            crypto_msg(M_FATAL, "Cannot load certificate file %s", cert_file);
+        }
+    }
+    else
+    {
+        crypto_print_openssl_errors(M_DEBUG);
+    }
+
+    if (in != NULL)
+    {
+        BIO_free(in);
+    }
+    if (x509)
+    {
+        *x509 = x;
+    }
+    else if (x)
+    {
+        X509_free(x);
+    }
+}
+
+void
+tls_ctx_load_cert_file(struct tls_root_ctx *ctx, const char *cert_file,
+                       const char *cert_file_inline)
+{
+    tls_ctx_load_cert_file_and_copy(ctx, cert_file, cert_file_inline, NULL);
+}
+
+int
+tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const char *priv_key_file,
+                       const char *priv_key_file_inline
+                       )
+{
+    SSL_CTX *ssl_ctx = NULL;
+    BIO *in = NULL;
+    EVP_PKEY *pkey = NULL;
+    int ret = 1;
+
+    ASSERT(NULL != ctx);
+
+    ssl_ctx = ctx->ctx;
+
+    if (!strcmp(priv_key_file, INLINE_FILE_TAG) && priv_key_file_inline)
+    {
+        in = BIO_new_mem_buf((char *)priv_key_file_inline, -1);
+    }
+    else
+    {
+        in = BIO_new_file(priv_key_file, "r");
+    }
+
+    if (!in)
+    {
+        goto end;
+    }
+
+    pkey = PEM_read_bio_PrivateKey(in, NULL,
+                                   SSL_CTX_get_default_passwd_cb(ctx->ctx),
+                                   SSL_CTX_get_default_passwd_cb_userdata(ctx->ctx));
+    if (!pkey || !SSL_CTX_use_PrivateKey(ssl_ctx, pkey))
+    {
+#ifdef ENABLE_MANAGEMENT
+        if (management && (ERR_GET_REASON(ERR_peek_error()) == EVP_R_BAD_DECRYPT))
+        {
+            management_auth_failure(management, UP_TYPE_PRIVATE_KEY, NULL);
+        }
+#endif
+        crypto_msg(M_WARN, "Cannot load private key file %s", priv_key_file);
+        goto end;
+    }
+
+    /* Check Private Key */
+    if (!SSL_CTX_check_private_key(ssl_ctx))
+    {
+        crypto_msg(M_FATAL, "Private key does not match the certificate");
+    }
+    ret = 0;
+
+end:
+    if (pkey)
+    {
+        EVP_PKEY_free(pkey);
+    }
+    if (in)
+    {
+        BIO_free(in);
+    }
+    return ret;
+}
+
+void
+backend_tls_ctx_reload_crl(struct tls_root_ctx *ssl_ctx, const char *crl_file,
+                           const char *crl_inline)
+{
+    BIO *in = NULL;
+
+    X509_STORE *store = SSL_CTX_get_cert_store(ssl_ctx->ctx);
+    if (!store)
+    {
+        crypto_msg(M_FATAL, "Cannot get certificate store");
+    }
+
+    /* Always start with a cleared CRL list, for that we
+     * we need to manually find the CRL object from the stack
+     * and remove it */
+    STACK_OF(X509_OBJECT) *objs = X509_STORE_get0_objects(store);
+    for (int i = 0; i < sk_X509_OBJECT_num(objs); i++)
+    {
+        X509_OBJECT *obj = sk_X509_OBJECT_value(objs, i);
+        ASSERT(obj);
+        if (X509_OBJECT_get_type(obj) == X509_LU_CRL)
+        {
+            sk_X509_OBJECT_delete(objs, i);
+            X509_OBJECT_free(obj);
+        }
+    }
+
+    X509_STORE_set_flags(store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL);
+
+    if (!strcmp(crl_file, INLINE_FILE_TAG) && crl_inline)
+    {
+        in = BIO_new_mem_buf((char *)crl_inline, -1);
+    }
+    else
+    {
+        in = BIO_new_file(crl_file, "r");
+    }
+
+    if (in == NULL)
+    {
+        msg(M_WARN, "CRL: cannot read: %s", crl_file);
+        goto end;
+    }
+
+    int num_crls_loaded = 0;
+    while (true)
+    {
+        X509_CRL *crl = PEM_read_bio_X509_CRL(in, NULL, NULL, NULL);
+        if (crl == NULL)
+        {
+            /*
+             * PEM_R_NO_START_LINE can be considered equivalent to EOF.
+             */
+            bool eof = ERR_GET_REASON(ERR_peek_error()) == PEM_R_NO_START_LINE;
+            /* but warn if no CRLs have been loaded */
+            if (num_crls_loaded > 0 && eof)
+            {
+                /* remove that error from error stack */
+                (void)ERR_get_error();
+                break;
+            }
+
+            crypto_msg(M_WARN, "CRL: cannot read CRL from file %s", crl_file);
+            break;
+        }
+
+        if (!X509_STORE_add_crl(store, crl))
+        {
+            X509_CRL_free(crl);
+            crypto_msg(M_WARN, "CRL: cannot add %s to store", crl_file);
+            break;
+        }
+        X509_CRL_free(crl);
+        num_crls_loaded++;
+    }
+    msg(M_INFO, "CRL: loaded %d CRLs from file %s", num_crls_loaded, crl_file);
+end:
+    BIO_free(in);
+}
+
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+/* encrypt */
+static int
+rsa_pub_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    ASSERT(0);
+    return -1;
+}
+
+/* verify arbitrary data */
+static int
+rsa_pub_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    ASSERT(0);
+    return -1;
+}
+
+/* decrypt */
+static int
+rsa_priv_dec(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    ASSERT(0);
+    return -1;
+}
+
+/* called at RSA_free */
+static int
+openvpn_extkey_rsa_finish(RSA *rsa)
+{
+    /* meth was allocated in tls_ctx_use_external_private_key() ; since
+     * this function is called when the parent RSA object is destroyed,
+     * it is no longer used after this point so kill it. */
+    const RSA_METHOD *meth = RSA_get_method(rsa);
+    RSA_meth_free((RSA_METHOD *)meth);
+    return 1;
+}
+
+/* sign arbitrary data */
+static int
+rsa_priv_enc(int flen, const unsigned char *from, unsigned char *to, RSA *rsa, int padding)
+{
+    /* optional app data in rsa->meth->app_data; */
+    char *in_b64 = NULL;
+    char *out_b64 = NULL;
+    int ret = -1;
+    int len;
+
+    if (padding != RSA_PKCS1_PADDING)
+    {
+        RSAerr(RSA_F_RSA_OSSL_PRIVATE_ENCRYPT, RSA_R_UNKNOWN_PADDING_TYPE);
+        goto done;
+    }
+
+    /* convert 'from' to base64 */
+    if (openvpn_base64_encode(from, flen, &in_b64) <= 0)
+    {
+        goto done;
+    }
+
+    /* call MI for signature */
+    if (management)
+    {
+        out_b64 = management_query_rsa_sig(management, in_b64);
+    }
+    if (!out_b64)
+    {
+        goto done;
+    }
+
+    /* decode base64 signature to binary */
+    len = RSA_size(rsa);
+    ret = openvpn_base64_decode(out_b64, to, len);
+
+    /* verify length */
+    if (ret != len)
+    {
+        ret = -1;
+    }
+
+done:
+    if (in_b64)
+    {
+        free(in_b64);
+    }
+    if (out_b64)
+    {
+        free(out_b64);
+    }
+    return ret;
+}
+
+int
+tls_ctx_use_external_private_key(struct tls_root_ctx *ctx,
+                                 const char *cert_file, const char *cert_file_inline)
+{
+    RSA *rsa = NULL;
+    RSA *pub_rsa;
+    RSA_METHOD *rsa_meth;
+    X509 *cert = NULL;
+
+    ASSERT(NULL != ctx);
+
+    tls_ctx_load_cert_file_and_copy(ctx, cert_file, cert_file_inline, &cert);
+
+    ASSERT(NULL != cert);
+
+    /* allocate custom RSA method object */
+    rsa_meth = RSA_meth_new("OpenVPN external private key RSA Method",
+                            RSA_METHOD_FLAG_NO_CHECK);
+    check_malloc_return(rsa_meth);
+    RSA_meth_set_pub_enc(rsa_meth, rsa_pub_enc);
+    RSA_meth_set_pub_dec(rsa_meth, rsa_pub_dec);
+    RSA_meth_set_priv_enc(rsa_meth, rsa_priv_enc);
+    RSA_meth_set_priv_dec(rsa_meth, rsa_priv_dec);
+    RSA_meth_set_init(rsa_meth, NULL);
+    RSA_meth_set_finish(rsa_meth, openvpn_extkey_rsa_finish);
+    RSA_meth_set0_app_data(rsa_meth, NULL);
+
+    /* allocate RSA object */
+    rsa = RSA_new();
+    if (rsa == NULL)
+    {
+        SSLerr(SSL_F_SSL_USE_PRIVATEKEY, ERR_R_MALLOC_FAILURE);
+        goto err;
+    }
+
+    /* get the public key */
+    EVP_PKEY *pkey = X509_get0_pubkey(cert);
+    ASSERT(pkey); /* NULL before SSL_CTX_use_certificate() is called */
+    pub_rsa = EVP_PKEY_get0_RSA(pkey);
+
+    /* Certificate might not be RSA but DSA or EC */
+    if (!pub_rsa)
+    {
+        crypto_msg(M_WARN, "management-external-key requires a RSA certificate");
+        goto err;
+    }
+
+    /* initialize RSA object */
+    const BIGNUM *n = NULL;
+    const BIGNUM *e = NULL;
+    RSA_get0_key(pub_rsa, &n, &e, NULL);
+    RSA_set0_key(rsa, BN_dup(n), BN_dup(e), NULL);
+    RSA_set_flags(rsa, RSA_flags(rsa) | RSA_FLAG_EXT_PKEY);
+    if (!RSA_set_method(rsa, rsa_meth))
+    {
+        goto err;
+    }
+
+    /* bind our custom RSA object to ssl_ctx */
+    if (!SSL_CTX_use_RSAPrivateKey(ctx->ctx, rsa))
+    {
+        goto err;
+    }
+
+    X509_free(cert);
+    RSA_free(rsa); /* doesn't necessarily free, just decrements refcount */
+    return 0;
+
+err:
+    if (cert)
+    {
+        X509_free(cert);
+    }
+    if (rsa)
+    {
+        RSA_free(rsa);
+    }
+    else
+    {
+        if (rsa_meth)
+        {
+            RSA_meth_free(rsa_meth);
+        }
+    }
+    crypto_msg(M_FATAL, "Cannot enable SSL external private key capability");
+    return 1;
+}
+
+#endif /* ifdef MANAGMENT_EXTERNAL_KEY */
+
+static int
+sk_x509_name_cmp(const X509_NAME *const *a, const X509_NAME *const *b)
+{
+    return X509_NAME_cmp(*a, *b);
+}
+
+void
+tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
+                const char *ca_file_inline,
+                const char *ca_path, bool tls_server
+                )
+{
+    STACK_OF(X509_INFO) *info_stack = NULL;
+    STACK_OF(X509_NAME) *cert_names = NULL;
+    X509_LOOKUP *lookup = NULL;
+    X509_STORE *store = NULL;
+    X509_NAME *xn = NULL;
+    BIO *in = NULL;
+    int i, added = 0, prev = 0;
+
+    ASSERT(NULL != ctx);
+
+    store = SSL_CTX_get_cert_store(ctx->ctx);
+    if (!store)
+    {
+        crypto_msg(M_FATAL, "Cannot get certificate store");
+    }
+
+    /* Try to add certificates and CRLs from ca_file */
+    if (ca_file)
+    {
+        if (!strcmp(ca_file, INLINE_FILE_TAG) && ca_file_inline)
+        {
+            in = BIO_new_mem_buf((char *)ca_file_inline, -1);
+        }
+        else
+        {
+            in = BIO_new_file(ca_file, "r");
+        }
+
+        if (in)
+        {
+            info_stack = PEM_X509_INFO_read_bio(in, NULL, NULL, NULL);
+        }
+
+        if (info_stack)
+        {
+            for (i = 0; i < sk_X509_INFO_num(info_stack); i++)
+            {
+                X509_INFO *info = sk_X509_INFO_value(info_stack, i);
+                if (info->crl)
+                {
+                    X509_STORE_add_crl(store, info->crl);
+                }
+
+                if (tls_server && !info->x509)
+                {
+                    crypto_msg(M_FATAL, "X509 name was missing in TLS mode");
+                }
+
+                if (info->x509)
+                {
+                    X509_STORE_add_cert(store, info->x509);
+                    added++;
+
+                    if (!tls_server)
+                    {
+                        continue;
+                    }
+
+                    /* Use names of CAs as a client CA list */
+                    if (cert_names == NULL)
+                    {
+                        cert_names = sk_X509_NAME_new(sk_x509_name_cmp);
+                        if (!cert_names)
+                        {
+                            continue;
+                        }
+                    }
+
+                    xn = X509_get_subject_name(info->x509);
+                    if (!xn)
+                    {
+                        continue;
+                    }
+
+                    /* Don't add duplicate CA names */
+                    if (sk_X509_NAME_find(cert_names, xn) == -1)
+                    {
+                        xn = X509_NAME_dup(xn);
+                        if (!xn)
+                        {
+                            continue;
+                        }
+                        sk_X509_NAME_push(cert_names, xn);
+                    }
+                }
+
+                if (tls_server)
+                {
+                    int cnum = sk_X509_NAME_num(cert_names);
+                    if (cnum != (prev + 1))
+                    {
+                        crypto_msg(M_WARN,
+                                   "Cannot load CA certificate file %s (entry %d did not validate)",
+                                   np(ca_file), added);
+                    }
+                    prev = cnum;
+                }
+
+            }
+            sk_X509_INFO_pop_free(info_stack, X509_INFO_free);
+        }
+
+        if (tls_server)
+        {
+            SSL_CTX_set_client_CA_list(ctx->ctx, cert_names);
+        }
+
+        if (!added)
+        {
+            crypto_msg(M_FATAL,
+                       "Cannot load CA certificate file %s (no entries were read)",
+                       np(ca_file));
+        }
+
+        if (tls_server)
+        {
+            int cnum = sk_X509_NAME_num(cert_names);
+            if (cnum != added)
+            {
+                crypto_msg(M_FATAL, "Cannot load CA certificate file %s (only %d "
+                           "of %d entries were valid X509 names)",
+                           np(ca_file), cnum, added);
+            }
+        }
+
+        if (in)
+        {
+            BIO_free(in);
+        }
+    }
+
+    /* Set a store for certs (CA & CRL) with a lookup on the "capath" hash directory */
+    if (ca_path)
+    {
+        lookup = X509_STORE_add_lookup(store, X509_LOOKUP_hash_dir());
+        if (lookup && X509_LOOKUP_add_dir(lookup, ca_path, X509_FILETYPE_PEM))
+        {
+            msg(M_WARN, "WARNING: experimental option --capath %s", ca_path);
+        }
+        else
+        {
+            crypto_msg(M_FATAL, "Cannot add lookup at --capath %s", ca_path);
+        }
+        X509_STORE_set_flags(store, X509_V_FLAG_CRL_CHECK | X509_V_FLAG_CRL_CHECK_ALL);
+    }
+}
+
+void
+tls_ctx_load_extra_certs(struct tls_root_ctx *ctx, const char *extra_certs_file,
+                         const char *extra_certs_file_inline
+                         )
+{
+    BIO *in;
+    if (!strcmp(extra_certs_file, INLINE_FILE_TAG) && extra_certs_file_inline)
+    {
+        in = BIO_new_mem_buf((char *)extra_certs_file_inline, -1);
+    }
+    else
+    {
+        in = BIO_new_file(extra_certs_file, "r");
+    }
+
+    if (in == NULL)
+    {
+        crypto_msg(M_FATAL, "Cannot load extra-certs file: %s", extra_certs_file);
+    }
+    else
+    {
+        tls_ctx_add_extra_certs(ctx, in, false);
+    }
+
+    BIO_free(in);
+}
+
+/* **************************************
+ *
+ * Key-state specific functions
+ *
+ ***************************************/
+/*
+ *
+ * BIO functions
+ *
+ */
+
+#ifdef BIO_DEBUG
+
+#warning BIO_DEBUG defined
+
+static FILE *biofp;                            /* GLOBAL */
+static bool biofp_toggle;                      /* GLOBAL */
+static time_t biofp_last_open;                 /* GLOBAL */
+static const int biofp_reopen_interval = 600;  /* GLOBAL */
+
+static void
+close_biofp(void)
+{
+    if (biofp)
+    {
+        ASSERT(!fclose(biofp));
+        biofp = NULL;
+    }
+}
+
+static void
+open_biofp(void)
+{
+    const time_t current = time(NULL);
+    const pid_t pid = getpid();
+
+    if (biofp_last_open + biofp_reopen_interval < current)
+    {
+        close_biofp();
+    }
+    if (!biofp)
+    {
+        char fn[256];
+        openvpn_snprintf(fn, sizeof(fn), "bio/%d-%d.log", pid, biofp_toggle);
+        biofp = fopen(fn, "w");
+        ASSERT(biofp);
+        biofp_last_open = time(NULL);
+        biofp_toggle ^= 1;
+    }
+}
+
+static void
+bio_debug_data(const char *mode, BIO *bio, const uint8_t *buf, int len, const char *desc)
+{
+    struct gc_arena gc = gc_new();
+    if (len > 0)
+    {
+        open_biofp();
+        fprintf(biofp, "BIO_%s %s time=" time_format " bio=" ptr_format " len=%d data=%s\n",
+                mode, desc, time(NULL), (ptr_type)bio, len, format_hex(buf, len, 0, &gc));
+        fflush(biofp);
+    }
+    gc_free(&gc);
+}
+
+static void
+bio_debug_oc(const char *mode, BIO *bio)
+{
+    open_biofp();
+    fprintf(biofp, "BIO %s time=" time_format " bio=" ptr_format "\n",
+            mode, time(NULL), (ptr_type)bio);
+    fflush(biofp);
+}
+
+#endif /* ifdef BIO_DEBUG */
+
+/*
+ * Write to an OpenSSL BIO in non-blocking mode.
+ */
+static int
+bio_write(BIO *bio, const uint8_t *data, int size, const char *desc)
+{
+    int i;
+    int ret = 0;
+    ASSERT(size >= 0);
+    if (size)
+    {
+        /*
+         * Free the L_TLS lock prior to calling BIO routines
+         * so that foreground thread can still call
+         * tls_pre_decrypt or tls_pre_encrypt,
+         * allowing tunnel packet forwarding to continue.
+         */
+#ifdef BIO_DEBUG
+        bio_debug_data("write", bio, data, size, desc);
+#endif
+        i = BIO_write(bio, data, size);
+
+        if (i < 0)
+        {
+            if (BIO_should_retry(bio))
+            {
+            }
+            else
+            {
+                crypto_msg(D_TLS_ERRORS, "TLS ERROR: BIO write %s error", desc);
+                ret = -1;
+                ERR_clear_error();
+            }
+        }
+        else if (i != size)
+        {
+            crypto_msg(D_TLS_ERRORS, "TLS ERROR: BIO write %s incomplete %d/%d",
+                       desc, i, size);
+            ret = -1;
+            ERR_clear_error();
+        }
+        else
+        {                       /* successful write */
+            dmsg(D_HANDSHAKE_VERBOSE, "BIO write %s %d bytes", desc, i);
+            ret = 1;
+        }
+    }
+    return ret;
+}
+
+/*
+ * Inline functions for reading from and writing
+ * to BIOs.
+ */
+
+static void
+bio_write_post(const int status, struct buffer *buf)
+{
+    if (status == 1) /* success status return from bio_write? */
+    {
+        memset(BPTR(buf), 0, BLEN(buf));  /* erase data just written */
+        buf->len = 0;
+    }
+}
+
+/*
+ * Read from an OpenSSL BIO in non-blocking mode.
+ */
+static int
+bio_read(BIO *bio, struct buffer *buf, int maxlen, const char *desc)
+{
+    int i;
+    int ret = 0;
+    ASSERT(buf->len >= 0);
+    if (buf->len)
+    {
+    }
+    else
+    {
+        int len = buf_forward_capacity(buf);
+        if (maxlen < len)
+        {
+            len = maxlen;
+        }
+
+        /*
+         * BIO_read brackets most of the serious RSA
+         * key negotiation number crunching.
+         */
+        i = BIO_read(bio, BPTR(buf), len);
+
+        VALGRIND_MAKE_READABLE((void *) &i, sizeof(i));
+
+#ifdef BIO_DEBUG
+        bio_debug_data("read", bio, BPTR(buf), i, desc);
+#endif
+        if (i < 0)
+        {
+            if (BIO_should_retry(bio))
+            {
+            }
+            else
+            {
+                crypto_msg(D_TLS_ERRORS, "TLS_ERROR: BIO read %s error", desc);
+                buf->len = 0;
+                ret = -1;
+                ERR_clear_error();
+            }
+        }
+        else if (!i)
+        {
+            buf->len = 0;
+        }
+        else
+        {                       /* successful read */
+            dmsg(D_HANDSHAKE_VERBOSE, "BIO read %s %d bytes", desc, i);
+            buf->len = i;
+            ret = 1;
+            VALGRIND_MAKE_READABLE((void *) BPTR(buf), BLEN(buf));
+        }
+    }
+    return ret;
+}
+
+void
+key_state_ssl_init(struct key_state_ssl *ks_ssl, const struct tls_root_ctx *ssl_ctx, bool is_server, struct tls_session *session)
+{
+    ASSERT(NULL != ssl_ctx);
+    ASSERT(ks_ssl);
+    CLEAR(*ks_ssl);
+
+    ks_ssl->ssl = SSL_new(ssl_ctx->ctx);
+    if (!ks_ssl->ssl)
+    {
+        crypto_msg(M_FATAL, "SSL_new failed");
+    }
+
+    /* put session * in ssl object so we can access it
+     * from verify callback*/
+    SSL_set_ex_data(ks_ssl->ssl, mydata_index, session);
+
+    ASSERT((ks_ssl->ssl_bio = BIO_new(BIO_f_ssl())));
+    ASSERT((ks_ssl->ct_in = BIO_new(BIO_s_mem())));
+    ASSERT((ks_ssl->ct_out = BIO_new(BIO_s_mem())));
+
+#ifdef BIO_DEBUG
+    bio_debug_oc("open ssl_bio", ks_ssl->ssl_bio);
+    bio_debug_oc("open ct_in", ks_ssl->ct_in);
+    bio_debug_oc("open ct_out", ks_ssl->ct_out);
+#endif
+
+    if (is_server)
+    {
+        SSL_set_accept_state(ks_ssl->ssl);
+    }
+    else
+    {
+        SSL_set_connect_state(ks_ssl->ssl);
+    }
+
+    SSL_set_bio(ks_ssl->ssl, ks_ssl->ct_in, ks_ssl->ct_out);
+    BIO_set_ssl(ks_ssl->ssl_bio, ks_ssl->ssl, BIO_NOCLOSE);
+}
+
+void
+key_state_ssl_free(struct key_state_ssl *ks_ssl)
+{
+    if (ks_ssl->ssl)
+    {
+#ifdef BIO_DEBUG
+        bio_debug_oc("close ssl_bio", ks_ssl->ssl_bio);
+        bio_debug_oc("close ct_in", ks_ssl->ct_in);
+        bio_debug_oc("close ct_out", ks_ssl->ct_out);
+#endif
+        BIO_free_all(ks_ssl->ssl_bio);
+        SSL_free(ks_ssl->ssl);
+    }
+}
+
+int
+key_state_write_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf)
+{
+    int ret = 0;
+    perf_push(PERF_BIO_WRITE_PLAINTEXT);
+
+#ifdef ENABLE_CRYPTO_OPENSSL
+    ASSERT(NULL != ks_ssl);
+
+    ret = bio_write(ks_ssl->ssl_bio, BPTR(buf), BLEN(buf),
+                    "tls_write_plaintext");
+    bio_write_post(ret, buf);
+#endif /* ENABLE_CRYPTO_OPENSSL */
+
+    perf_pop();
+    return ret;
+}
+
+int
+key_state_write_plaintext_const(struct key_state_ssl *ks_ssl, const uint8_t *data, int len)
+{
+    int ret = 0;
+    perf_push(PERF_BIO_WRITE_PLAINTEXT);
+
+    ASSERT(NULL != ks_ssl);
+
+    ret = bio_write(ks_ssl->ssl_bio, data, len, "tls_write_plaintext_const");
+
+    perf_pop();
+    return ret;
+}
+
+int
+key_state_read_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf,
+                          int maxlen)
+{
+    int ret = 0;
+    perf_push(PERF_BIO_READ_CIPHERTEXT);
+
+    ASSERT(NULL != ks_ssl);
+
+    ret = bio_read(ks_ssl->ct_out, buf, maxlen, "tls_read_ciphertext");
+
+    perf_pop();
+    return ret;
+}
+
+int
+key_state_write_ciphertext(struct key_state_ssl *ks_ssl, struct buffer *buf)
+{
+    int ret = 0;
+    perf_push(PERF_BIO_WRITE_CIPHERTEXT);
+
+    ASSERT(NULL != ks_ssl);
+
+    ret = bio_write(ks_ssl->ct_in, BPTR(buf), BLEN(buf), "tls_write_ciphertext");
+    bio_write_post(ret, buf);
+
+    perf_pop();
+    return ret;
+}
+
+int
+key_state_read_plaintext(struct key_state_ssl *ks_ssl, struct buffer *buf,
+                         int maxlen)
+{
+    int ret = 0;
+    perf_push(PERF_BIO_READ_PLAINTEXT);
+
+    ASSERT(NULL != ks_ssl);
+
+    ret = bio_read(ks_ssl->ssl_bio, buf, maxlen, "tls_read_plaintext");
+
+    perf_pop();
+    return ret;
+}
+
+/* **************************************
+ *
+ * Information functions
+ *
+ * Print information for the end user.
+ *
+ ***************************************/
+void
+print_details(struct key_state_ssl *ks_ssl, const char *prefix)
+{
+    const SSL_CIPHER *ciph;
+    X509 *cert;
+    char s1[256];
+    char s2[256];
+
+    s1[0] = s2[0] = 0;
+    ciph = SSL_get_current_cipher(ks_ssl->ssl);
+    openvpn_snprintf(s1, sizeof(s1), "%s %s, cipher %s %s",
+                     prefix,
+                     SSL_get_version(ks_ssl->ssl),
+                     SSL_CIPHER_get_version(ciph),
+                     SSL_CIPHER_get_name(ciph));
+    cert = SSL_get_peer_certificate(ks_ssl->ssl);
+    if (cert != NULL)
+    {
+        EVP_PKEY *pkey = X509_get_pubkey(cert);
+        if (pkey != NULL)
+        {
+            if ((EVP_PKEY_id(pkey) == EVP_PKEY_RSA) && (EVP_PKEY_get0_RSA(pkey) != NULL))
+            {
+                RSA *rsa = EVP_PKEY_get0_RSA(pkey);
+                openvpn_snprintf(s2, sizeof(s2), ", %d bit RSA",
+                                 RSA_bits(rsa));
+            }
+            else if ((EVP_PKEY_id(pkey) == EVP_PKEY_DSA) && (EVP_PKEY_get0_DSA(pkey) != NULL))
+            {
+                DSA *dsa = EVP_PKEY_get0_DSA(pkey);
+                openvpn_snprintf(s2, sizeof(s2), ", %d bit DSA",
+                                 DSA_bits(dsa));
+            }
+#ifndef OPENSSL_NO_EC
+            else if ((EVP_PKEY_id(pkey) == EVP_PKEY_EC) && (EVP_PKEY_get0_EC_KEY(pkey) != NULL))
+            {
+                EC_KEY *ec = EVP_PKEY_get0_EC_KEY(pkey);
+                const EC_GROUP *group = EC_KEY_get0_group(ec);
+                const char* curve;
+
+                int nid = EC_GROUP_get_curve_name(group);
+                if (nid == 0 || (curve = OBJ_nid2sn(nid)) == NULL)
+                {
+                    curve = "Error getting curve name";
+                }
+
+                openvpn_snprintf(s2, sizeof(s2), ", %d bit EC, curve: %s",
+                                 EC_GROUP_order_bits(group), curve);
+
+            }
+#endif
+            EVP_PKEY_free(pkey);
+        }
+        X509_free(cert);
+    }
+    /* The SSL API does not allow us to look at temporary RSA/DH keys,
+     * otherwise we should print their lengths too */
+    msg(D_HANDSHAKE, "%s%s", s1, s2);
+}
+
+void
+show_available_tls_ciphers_list(const char *cipher_list,
+                                const char *tls_cert_profile,
+                                const bool tls13)
+{
+    struct tls_root_ctx tls_ctx;
+
+    tls_ctx.ctx = SSL_CTX_new(SSLv23_method());
+    if (!tls_ctx.ctx)
+    {
+        crypto_msg(M_FATAL, "Cannot create SSL_CTX object");
+    }
+
+#if (OPENSSL_VERSION_NUMBER >= 0x1010100fL) && defined(TLS1_3_VERSION) && !defined(OPENSSL_NO_TLS1_3)
+    if (tls13)
+    {
+        SSL_CTX_set_min_proto_version(tls_ctx.ctx, TLS1_3_VERSION);
+        tls_ctx_restrict_ciphers_tls13(&tls_ctx, cipher_list);
+    }
+    else
+#endif
+    {
+        SSL_CTX_set_max_proto_version(tls_ctx.ctx, TLS1_2_VERSION);
+        tls_ctx_restrict_ciphers(&tls_ctx, cipher_list);
+    }
+
+    tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile);
+
+    SSL *ssl = SSL_new(tls_ctx.ctx);
+    if (!ssl)
+    {
+        crypto_msg(M_FATAL, "Cannot create SSL object");
+    }
+
+#if (OPENSSL_VERSION_NUMBER < 0x1010000fL)
+    STACK_OF(SSL_CIPHER) *sk = SSL_get_ciphers(ssl);
+#else
+    STACK_OF(SSL_CIPHER) *sk = SSL_get1_supported_ciphers(ssl);
+#endif
+    for (int i=0;i < sk_SSL_CIPHER_num(sk);i++)
+    {
+        const SSL_CIPHER *c = sk_SSL_CIPHER_value(sk, i);
+
+        const char *cipher_name = SSL_CIPHER_get_name(c);
+
+        const tls_cipher_name_pair *pair =
+            tls_get_cipher_name_pair(cipher_name, strlen(cipher_name));
+
+        if (tls13)
+        {
+              printf("%s\n", cipher_name);
+        }
+        else if (NULL == pair)
+        {
+            /* No translation found, print warning */
+            printf("%s (No IANA name known to OpenVPN, use OpenSSL name.)\n",
+                   cipher_name);
+        }
+        else
+        {
+            printf("%s\n", pair->iana_name);
+        }
+    }
+#if (OPENSSL_VERSION_NUMBER >= 0x1010000fL)
+    sk_SSL_CIPHER_free(sk);
+#endif
+    SSL_free(ssl);
+    SSL_CTX_free(tls_ctx.ctx);
+}
+
+/*
+ * Show the Elliptic curves that are available for us to use
+ * in the OpenSSL library.
+ */
+void
+show_available_curves(void)
+{
+#ifndef OPENSSL_NO_EC
+    EC_builtin_curve *curves = NULL;
+    size_t crv_len = 0;
+    size_t n = 0;
+
+    crv_len = EC_get_builtin_curves(NULL, 0);
+    ALLOC_ARRAY(curves, EC_builtin_curve, crv_len);
+    if (EC_get_builtin_curves(curves, crv_len))
+    {
+        printf("Available Elliptic curves:\n");
+        for (n = 0; n < crv_len; n++)
+        {
+            const char *sname;
+            sname   = OBJ_nid2sn(curves[n].nid);
+            if (sname == NULL)
+            {
+                sname = "";
+            }
+
+            printf("%s\n", sname);
+        }
+    }
+    else
+    {
+        crypto_msg(M_FATAL, "Cannot get list of builtin curves");
+    }
+    free(curves);
+#else  /* ifndef OPENSSL_NO_EC */
+    msg(M_WARN, "Your OpenSSL library was built without elliptic curve support. "
+        "No curves available.");
+#endif /* ifndef OPENSSL_NO_EC */
+}
+
+void
+get_highest_preference_tls_cipher(char *buf, int size)
+{
+    SSL_CTX *ctx;
+    SSL *ssl;
+    const char *cipher_name;
+
+    ctx = SSL_CTX_new(SSLv23_method());
+    if (!ctx)
+    {
+        crypto_msg(M_FATAL, "Cannot create SSL_CTX object");
+    }
+    ssl = SSL_new(ctx);
+    if (!ssl)
+    {
+        crypto_msg(M_FATAL, "Cannot create SSL object");
+    }
+
+    cipher_name = SSL_get_cipher_list(ssl, 0);
+    strncpynt(buf, cipher_name, size);
+
+    SSL_free(ssl);
+    SSL_CTX_free(ctx);
+}
+
+const char *
+get_ssl_library_version(void)
+{
+    return SSLeay_version(SSLEAY_VERSION);
+}
+
+#endif /* defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL) */
diff --git a/src/openvpn/ssl_openssl.h b/src/openvpn/ssl_openssl.h
new file mode 100644
index 0000000..dabb941
--- /dev/null
+++ b/src/openvpn/ssl_openssl.h
@@ -0,0 +1,70 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel OpenSSL Backend
+ */
+
+#ifndef SSL_OPENSSL_H_
+#define SSL_OPENSSL_H_
+
+#include <openssl/ssl.h>
+
+/**
+ * SSL_OP_NO_TICKET tells OpenSSL to disable "stateless session resumption",
+ * as this is something we do not want nor need, but could potentially be
+ * used for a future attack.  For compatibility reasons we keep building if the
+ * OpenSSL version is too old (pre-0.9.8f) to support stateless session
+ * resumption (and the accompanying SSL_OP_NO_TICKET flag).
+ */
+#ifndef SSL_OP_NO_TICKET
+#define SSL_OP_NO_TICKET 0
+#endif
+
+/**
+ * Structure that wraps the TLS context. Contents differ depending on the
+ * SSL library used.
+ */
+struct tls_root_ctx {
+    SSL_CTX *ctx;
+    time_t crl_last_mtime;
+    off_t crl_last_size;
+};
+
+struct key_state_ssl {
+    SSL *ssl;                   /* SSL object -- new obj created for each new key */
+    BIO *ssl_bio;                       /* read/write plaintext from here */
+    BIO *ct_in;                 /* write ciphertext to here */
+    BIO *ct_out;                        /* read ciphertext from here */
+};
+
+/**
+ * Allocate space in SSL objects in which to store a struct tls_session
+ * pointer back to parent.
+ */
+extern int mydata_index; /* GLOBAL */
+
+void openssl_set_mydata_index(void);
+
+#endif /* SSL_OPENSSL_H_ */
diff --git a/src/openvpn/ssl_verify.c b/src/openvpn/ssl_verify.c
new file mode 100644
index 0000000..c7e595e
--- /dev/null
+++ b/src/openvpn/ssl_verify.c
@@ -0,0 +1,1545 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+
+#include "misc.h"
+#include "manage.h"
+#include "otime.h"
+#include "base64.h"
+#include "ssl_verify.h"
+#include "ssl_verify_backend.h"
+
+#ifdef ENABLE_CRYPTO_OPENSSL
+#include "ssl_verify_openssl.h"
+#endif
+
+/** Maximum length of common name */
+#define TLS_USERNAME_LEN 64
+
+/** Legal characters in an X509 name with --compat-names */
+#define X509_NAME_CHAR_CLASS   (CC_ALNUM|CC_UNDERBAR|CC_DASH|CC_DOT|CC_AT|CC_SLASH|CC_COLON|CC_EQUAL)
+
+/** Legal characters in a common name with --compat-names */
+#define COMMON_NAME_CHAR_CLASS (CC_ALNUM|CC_UNDERBAR|CC_DASH|CC_DOT|CC_AT|CC_SLASH)
+
+static void
+string_mod_remap_name(char *str, const unsigned int restrictive_flags)
+{
+    if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NAMES)
+        && !compat_flag(COMPAT_FLAG_QUERY | COMPAT_NO_NAME_REMAPPING))
+    {
+        string_mod(str, restrictive_flags, 0, '_');
+    }
+    else
+    {
+        string_mod(str, CC_PRINT, CC_CRLF, '_');
+    }
+}
+
+/*
+ * Export the untrusted IP address and port to the environment
+ */
+static void
+setenv_untrusted(struct tls_session *session)
+{
+    setenv_link_socket_actual(session->opt->es, "untrusted", &session->untrusted_addr, SA_IP_PORT);
+}
+
+
+/**
+ *  Wipes the authentication token out of the memory, frees and cleans up related buffers and flags
+ *
+ *  @param multi  Pointer to a multi object holding the auth_token variables
+ */
+static void
+wipe_auth_token(struct tls_multi *multi)
+{
+    if(multi)
+    {
+        if (multi->auth_token)
+        {
+            secure_memzero(multi->auth_token, AUTH_TOKEN_SIZE);
+            free(multi->auth_token);
+        }
+        multi->auth_token = NULL;
+        multi->auth_token_sent = false;
+    }
+}
+
+
+/*
+ * Remove authenticated state from all sessions in the given tunnel
+ */
+static void
+tls_deauthenticate(struct tls_multi *multi)
+{
+    if (multi)
+    {
+        wipe_auth_token(multi);
+        for (int i = 0; i < TM_SIZE; ++i)
+        {
+            for (int j = 0; j < KS_SIZE; ++j)
+            {
+                multi->session[i].key[j].authenticated = false;
+            }
+        }
+    }
+}
+
+/*
+ * Set the given session's common_name
+ */
+static void
+set_common_name(struct tls_session *session, const char *common_name)
+{
+    if (session->common_name)
+    {
+        free(session->common_name);
+        session->common_name = NULL;
+#ifdef ENABLE_PF
+        session->common_name_hashval = 0;
+#endif
+    }
+    if (common_name)
+    {
+        /* FIXME: Last alloc will never be freed */
+        session->common_name = string_alloc(common_name, NULL);
+#ifdef ENABLE_PF
+        {
+            const uint32_t len = (uint32_t) strlen(common_name);
+            if (len)
+            {
+                session->common_name_hashval = hash_func((const uint8_t *)common_name, len+1, 0);
+            }
+            else
+            {
+                session->common_name_hashval = 0;
+            }
+        }
+#endif
+    }
+}
+
+/*
+ * Retrieve the common name for the given tunnel's active session. If the
+ * common name is NULL or empty, return NULL if null is true, or "UNDEF" if
+ * null is false.
+ */
+const char *
+tls_common_name(const struct tls_multi *multi, const bool null)
+{
+    const char *ret = NULL;
+    if (multi)
+    {
+        ret = multi->session[TM_ACTIVE].common_name;
+    }
+    if (ret && strlen(ret))
+    {
+        return ret;
+    }
+    else if (null)
+    {
+        return NULL;
+    }
+    else
+    {
+        return "UNDEF";
+    }
+}
+
+/*
+ * Lock the common name for the given tunnel.
+ */
+void
+tls_lock_common_name(struct tls_multi *multi)
+{
+    const char *cn = multi->session[TM_ACTIVE].common_name;
+    if (cn && !multi->locked_cn)
+    {
+        multi->locked_cn = string_alloc(cn, NULL);
+    }
+}
+
+/*
+ * Lock the username for the given tunnel
+ */
+static bool
+tls_lock_username(struct tls_multi *multi, const char *username)
+{
+    if (multi->locked_username)
+    {
+        if (!username || strcmp(username, multi->locked_username))
+        {
+            msg(D_TLS_ERRORS, "TLS Auth Error: username attempted to change from '%s' to '%s' -- tunnel disabled",
+                multi->locked_username,
+                np(username));
+
+            /* disable the tunnel */
+            tls_deauthenticate(multi);
+            return false;
+        }
+    }
+    else
+    {
+        if (username)
+        {
+            multi->locked_username = string_alloc(username, NULL);
+        }
+    }
+    return true;
+}
+
+const char *
+tls_username(const struct tls_multi *multi, const bool null)
+{
+    const char *ret = NULL;
+    if (multi)
+    {
+        ret = multi->locked_username;
+    }
+    if (ret && strlen(ret))
+    {
+        return ret;
+    }
+    else if (null)
+    {
+        return NULL;
+    }
+    else
+    {
+        return "UNDEF";
+    }
+}
+
+void
+cert_hash_remember(struct tls_session *session, const int error_depth,
+                   const struct buffer *cert_hash)
+{
+    if (error_depth >= 0 && error_depth < MAX_CERT_DEPTH)
+    {
+        if (!session->cert_hash_set)
+        {
+            ALLOC_OBJ_CLEAR(session->cert_hash_set, struct cert_hash_set);
+        }
+        if (!session->cert_hash_set->ch[error_depth])
+        {
+            ALLOC_OBJ(session->cert_hash_set->ch[error_depth], struct cert_hash);
+        }
+
+        struct cert_hash *ch = session->cert_hash_set->ch[error_depth];
+        ASSERT(sizeof(ch->sha256_hash) == BLEN(cert_hash));
+        memcpy(ch->sha256_hash, BPTR(cert_hash), sizeof(ch->sha256_hash));
+    }
+}
+
+void
+cert_hash_free(struct cert_hash_set *chs)
+{
+    if (chs)
+    {
+        int i;
+        for (i = 0; i < MAX_CERT_DEPTH; ++i)
+        {
+            free(chs->ch[i]);
+        }
+        free(chs);
+    }
+}
+
+bool
+cert_hash_compare(const struct cert_hash_set *chs1, const struct cert_hash_set *chs2)
+{
+    if (chs1 && chs2)
+    {
+        int i;
+        for (i = 0; i < MAX_CERT_DEPTH; ++i)
+        {
+            const struct cert_hash *ch1 = chs1->ch[i];
+            const struct cert_hash *ch2 = chs2->ch[i];
+
+            if (!ch1 && !ch2)
+            {
+                continue;
+            }
+            else if (ch1 && ch2 && !memcmp(ch1->sha256_hash, ch2->sha256_hash,
+                                           sizeof(ch1->sha256_hash)))
+            {
+                continue;
+            }
+            else
+            {
+                return false;
+            }
+        }
+        return true;
+    }
+    else if (!chs1 && !chs2)
+    {
+        return true;
+    }
+    else
+    {
+        return false;
+    }
+}
+
+static struct cert_hash_set *
+cert_hash_copy(const struct cert_hash_set *chs)
+{
+    struct cert_hash_set *dest = NULL;
+    if (chs)
+    {
+        int i;
+        ALLOC_OBJ_CLEAR(dest, struct cert_hash_set);
+        for (i = 0; i < MAX_CERT_DEPTH; ++i)
+        {
+            const struct cert_hash *ch = chs->ch[i];
+            if (ch)
+            {
+                ALLOC_OBJ(dest->ch[i], struct cert_hash);
+                memcpy(dest->ch[i]->sha256_hash, ch->sha256_hash,
+                       sizeof(dest->ch[i]->sha256_hash));
+            }
+        }
+    }
+    return dest;
+}
+void
+tls_lock_cert_hash_set(struct tls_multi *multi)
+{
+    const struct cert_hash_set *chs = multi->session[TM_ACTIVE].cert_hash_set;
+    if (chs && !multi->locked_cert_hash_set)
+    {
+        multi->locked_cert_hash_set = cert_hash_copy(chs);
+    }
+}
+
+/*
+ * Returns the string associated with the given certificate type.
+ */
+static const char *
+print_nsCertType(int type)
+{
+    switch (type)
+    {
+        case NS_CERT_CHECK_SERVER:
+            return "SERVER";
+
+        case NS_CERT_CHECK_CLIENT:
+            return "CLIENT";
+
+        default:
+            return "?";
+    }
+}
+
+/*
+ * Verify the peer's certificate fields.
+ *
+ * @param opt the tls options to verify against
+ * @param peer_cert the peer's certificate
+ * @param subject the peer's extracted subject name
+ * @param subject the peer's extracted common name
+ */
+static result_t
+verify_peer_cert(const struct tls_options *opt, openvpn_x509_cert_t *peer_cert,
+                 const char *subject, const char *common_name)
+{
+    /* verify certificate nsCertType */
+    if (opt->ns_cert_type != NS_CERT_CHECK_NONE)
+    {
+        if (SUCCESS == x509_verify_ns_cert_type(peer_cert, opt->ns_cert_type))
+        {
+            msg(D_HANDSHAKE, "VERIFY OK: nsCertType=%s",
+                print_nsCertType(opt->ns_cert_type));
+        }
+        else
+        {
+            msg(D_HANDSHAKE, "VERIFY nsCertType ERROR: %s, require nsCertType=%s",
+                subject, print_nsCertType(opt->ns_cert_type));
+            return FAILURE;             /* Reject connection */
+        }
+    }
+
+    /* verify certificate ku */
+    if (opt->remote_cert_ku[0] != 0)
+    {
+        if (SUCCESS == x509_verify_cert_ku(peer_cert, opt->remote_cert_ku, MAX_PARMS))
+        {
+            msg(D_HANDSHAKE, "VERIFY KU OK");
+        }
+        else
+        {
+            msg(D_HANDSHAKE, "VERIFY KU ERROR");
+            return FAILURE;             /* Reject connection */
+        }
+    }
+
+    /* verify certificate eku */
+    if (opt->remote_cert_eku != NULL)
+    {
+        if (SUCCESS == x509_verify_cert_eku(peer_cert, opt->remote_cert_eku))
+        {
+            msg(D_HANDSHAKE, "VERIFY EKU OK");
+        }
+        else
+        {
+            msg(D_HANDSHAKE, "VERIFY EKU ERROR");
+            return FAILURE;             /* Reject connection */
+        }
+    }
+
+    /* verify X509 name or username against --verify-x509-[user]name */
+    if (opt->verify_x509_type != VERIFY_X509_NONE)
+    {
+        if ( (opt->verify_x509_type == VERIFY_X509_SUBJECT_DN
+              && strcmp(opt->verify_x509_name, subject) == 0)
+             || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN
+                 && strcmp(opt->verify_x509_name, common_name) == 0)
+             || (opt->verify_x509_type == VERIFY_X509_SUBJECT_RDN_PREFIX
+                 && strncmp(opt->verify_x509_name, common_name,
+                            strlen(opt->verify_x509_name)) == 0) )
+        {
+            msg(D_HANDSHAKE, "VERIFY X509NAME OK: %s", subject);
+        }
+        else
+        {
+            msg(D_HANDSHAKE, "VERIFY X509NAME ERROR: %s, must be %s",
+                subject, opt->verify_x509_name);
+            return FAILURE;             /* Reject connection */
+        }
+    }
+
+    return SUCCESS;
+}
+
+/*
+ * Export the subject, common_name, and raw certificate fields to the
+ * environment for later verification by scripts and plugins.
+ */
+static void
+verify_cert_set_env(struct env_set *es, openvpn_x509_cert_t *peer_cert, int cert_depth,
+                    const char *subject, const char *common_name,
+                    const struct x509_track *x509_track)
+{
+    char envname[64];
+    char *serial = NULL;
+    struct gc_arena gc = gc_new();
+
+    /* Save X509 fields in environment */
+    if (x509_track)
+    {
+        x509_setenv_track(x509_track, es, cert_depth, peer_cert);
+    }
+    else
+    {
+        x509_setenv(es, cert_depth, peer_cert);
+    }
+
+    /* export subject name string as environmental variable */
+    openvpn_snprintf(envname, sizeof(envname), "tls_id_%d", cert_depth);
+    setenv_str(es, envname, subject);
+
+#if 0
+    /* export common name string as environmental variable */
+    openvpn_snprintf(envname, sizeof(envname), "tls_common_name_%d", cert_depth);
+    setenv_str(es, envname, common_name);
+#endif
+
+    /* export X509 cert fingerprints */
+    {
+        struct buffer sha1 = x509_get_sha1_fingerprint(peer_cert, &gc);
+        struct buffer sha256 = x509_get_sha256_fingerprint(peer_cert, &gc);
+
+        openvpn_snprintf(envname, sizeof(envname), "tls_digest_%d", cert_depth);
+        setenv_str(es, envname,
+                   format_hex_ex(BPTR(&sha1), BLEN(&sha1), 0, 1, ":", &gc));
+
+        openvpn_snprintf(envname, sizeof(envname), "tls_digest_sha256_%d",
+                         cert_depth);
+        setenv_str(es, envname,
+                   format_hex_ex(BPTR(&sha256), BLEN(&sha256), 0, 1, ":", &gc));
+    }
+
+    /* export serial number as environmental variable */
+    serial = backend_x509_get_serial(peer_cert, &gc);
+    openvpn_snprintf(envname, sizeof(envname), "tls_serial_%d", cert_depth);
+    setenv_str(es, envname, serial);
+
+    /* export serial number in hex as environmental variable */
+    serial = backend_x509_get_serial_hex(peer_cert, &gc);
+    openvpn_snprintf(envname, sizeof(envname), "tls_serial_hex_%d", cert_depth);
+    setenv_str(es, envname, serial);
+
+    gc_free(&gc);
+}
+
+/*
+ * call --tls-verify plug-in(s)
+ */
+static result_t
+verify_cert_call_plugin(const struct plugin_list *plugins, struct env_set *es,
+                        int cert_depth, openvpn_x509_cert_t *cert, char *subject)
+{
+    if (plugin_defined(plugins, OPENVPN_PLUGIN_TLS_VERIFY))
+    {
+        int ret;
+        struct argv argv = argv_new();
+
+        argv_printf(&argv, "%d %s", cert_depth, subject);
+
+        ret = plugin_call_ssl(plugins, OPENVPN_PLUGIN_TLS_VERIFY, &argv, NULL, es, cert_depth, cert);
+
+        argv_reset(&argv);
+
+        if (ret == OPENVPN_PLUGIN_FUNC_SUCCESS)
+        {
+            msg(D_HANDSHAKE, "VERIFY PLUGIN OK: depth=%d, %s",
+                cert_depth, subject);
+        }
+        else
+        {
+            msg(D_HANDSHAKE, "VERIFY PLUGIN ERROR: depth=%d, %s",
+                cert_depth, subject);
+            return FAILURE;             /* Reject connection */
+        }
+    }
+    return SUCCESS;
+}
+
+static const char *
+verify_cert_export_cert(openvpn_x509_cert_t *peercert, const char *tmp_dir, struct gc_arena *gc)
+{
+    FILE *peercert_file;
+    const char *peercert_filename = "";
+
+    /* create tmp file to store peer cert */
+    if (!tmp_dir
+        || !(peercert_filename = create_temp_file(tmp_dir, "pcf", gc)))
+    {
+        msg (M_WARN, "Failed to create peer cert file");
+        return NULL;
+    }
+
+    /* write peer-cert in tmp-file */
+    peercert_file = fopen(peercert_filename, "w+");
+    if (!peercert_file)
+    {
+        msg(M_ERR, "Failed to open temporary file : %s", peercert_filename);
+        return NULL;
+    }
+
+    if (SUCCESS != x509_write_pem(peercert_file, peercert))
+    {
+        msg(M_ERR, "Error writing PEM file containing certificate");
+    }
+
+    fclose(peercert_file);
+    return peercert_filename;
+}
+
+
+/*
+ * run --tls-verify script
+ */
+static result_t
+verify_cert_call_command(const char *verify_command, struct env_set *es,
+                         int cert_depth, openvpn_x509_cert_t *cert, char *subject, const char *verify_export_cert)
+{
+    const char *tmp_file = NULL;
+    int ret;
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+
+    setenv_str(es, "script_type", "tls-verify");
+
+    if (verify_export_cert)
+    {
+        tmp_file = verify_cert_export_cert(cert, verify_export_cert, &gc);
+        if (!tmp_file)
+        {
+            ret = false;
+            goto cleanup;
+        }
+        setenv_str(es, "peer_cert", tmp_file);
+    }
+
+    argv_parse_cmd(&argv, verify_command);
+    argv_printf_cat(&argv, "%d %s", cert_depth, subject);
+
+    argv_msg_prefix(D_TLS_DEBUG, &argv, "TLS: executing verify command");
+    ret = openvpn_run_script(&argv, es, 0, "--tls-verify script");
+
+    if (verify_export_cert)
+    {
+        if (tmp_file)
+        {
+            platform_unlink(tmp_file);
+        }
+    }
+
+cleanup:
+    gc_free(&gc);
+    argv_reset(&argv);
+
+    if (ret)
+    {
+        msg(D_HANDSHAKE, "VERIFY SCRIPT OK: depth=%d, %s",
+            cert_depth, subject);
+        return SUCCESS;
+    }
+
+    msg(D_HANDSHAKE, "VERIFY SCRIPT ERROR: depth=%d, %s",
+        cert_depth, subject);
+    return FAILURE;             /* Reject connection */
+}
+
+/*
+ * check peer cert against CRL directory
+ */
+static result_t
+verify_check_crl_dir(const char *crl_dir, openvpn_x509_cert_t *cert)
+{
+    result_t ret = FAILURE;
+    char fn[256];
+    int fd = -1;
+    struct gc_arena gc = gc_new();
+
+    char *serial = backend_x509_get_serial(cert, &gc);
+
+    if (!openvpn_snprintf(fn, sizeof(fn), "%s%c%s", crl_dir, OS_SPECIFIC_DIRSEP, serial))
+    {
+        msg(D_HANDSHAKE, "VERIFY CRL: filename overflow");
+        goto cleanup;
+    }
+    fd = platform_open(fn, O_RDONLY, 0);
+    if (fd >= 0)
+    {
+        msg(D_HANDSHAKE, "VERIFY CRL: certificate serial number %s is revoked", serial);
+        goto cleanup;
+    }
+
+    ret = SUCCESS;
+
+cleanup:
+
+    if (fd != -1)
+    {
+        close(fd);
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+result_t
+verify_cert(struct tls_session *session, openvpn_x509_cert_t *cert, int cert_depth)
+{
+    result_t ret = FAILURE;
+    char *subject = NULL;
+    char common_name[TLS_USERNAME_LEN+1] = {0}; /* null-terminated */
+    const struct tls_options *opt;
+    struct gc_arena gc = gc_new();
+
+    opt = session->opt;
+    ASSERT(opt);
+
+    session->verified = false;
+
+    /* get the X509 name */
+    subject = x509_get_subject(cert, &gc);
+    if (!subject)
+    {
+        msg(D_TLS_ERRORS, "VERIFY ERROR: depth=%d, could not extract X509 "
+            "subject string from certificate", cert_depth);
+        goto cleanup;
+    }
+
+    /* enforce character class restrictions in X509 name */
+    string_mod_remap_name(subject, X509_NAME_CHAR_CLASS);
+    string_replace_leading(subject, '-', '_');
+
+    /* extract the username (default is CN) */
+    if (SUCCESS != backend_x509_get_username(common_name, sizeof(common_name),
+                                             opt->x509_username_field, cert))
+    {
+        if (!cert_depth)
+        {
+            msg(D_TLS_ERRORS, "VERIFY ERROR: could not extract %s from X509 "
+                "subject string ('%s') -- note that the username length is "
+                "limited to %d characters",
+                opt->x509_username_field,
+                subject,
+                TLS_USERNAME_LEN);
+            goto cleanup;
+        }
+    }
+
+    /* enforce character class restrictions in common name */
+    string_mod_remap_name(common_name, COMMON_NAME_CHAR_CLASS);
+
+    /* warn if cert chain is too deep */
+    if (cert_depth >= MAX_CERT_DEPTH)
+    {
+        msg(D_TLS_ERRORS, "TLS Error: Convoluted certificate chain detected with depth [%d] greater than %d", cert_depth, MAX_CERT_DEPTH);
+        goto cleanup;                   /* Reject connection */
+    }
+
+    /* verify level 1 cert, i.e. the CA that signed our leaf cert */
+    if (cert_depth == 1 && opt->verify_hash)
+    {
+        struct buffer ca_hash = {0};
+
+        switch (opt->verify_hash_algo)
+        {
+        case MD_SHA1:
+            ca_hash = x509_get_sha1_fingerprint(cert, &gc);
+            break;
+
+        case MD_SHA256:
+            ca_hash = x509_get_sha256_fingerprint(cert, &gc);
+            break;
+
+        default:
+            /* This should normally not happen at all; the algorithm used
+             * is parsed by add_option() [options.c] and set to a predefined
+             * value in an enumerated type.  So if this unlikely scenario
+             * happens, consider this a failure
+             */
+            msg(M_WARN, "Unexpected invalid algorithm used with "
+                "--verify-hash (%i)", opt->verify_hash_algo);
+            ret = FAILURE;
+            goto cleanup;
+        }
+
+        if (memcmp(BPTR(&ca_hash), opt->verify_hash, BLEN(&ca_hash)))
+        {
+            msg(D_TLS_ERRORS, "TLS Error: level-1 certificate hash verification failed");
+            goto cleanup;
+        }
+    }
+
+    /* save common name in session object */
+    if (cert_depth == 0)
+    {
+        set_common_name(session, common_name);
+    }
+
+    session->verify_maxlevel = max_int(session->verify_maxlevel, cert_depth);
+
+    /* export certificate values to the environment */
+    verify_cert_set_env(opt->es, cert, cert_depth, subject, common_name,
+                        opt->x509_track);
+
+    /* export current untrusted IP */
+    setenv_untrusted(session);
+
+    /* If this is the peer's own certificate, verify it */
+    if (cert_depth == 0 && SUCCESS != verify_peer_cert(opt, cert, subject, common_name))
+    {
+        goto cleanup;
+    }
+
+    /* call --tls-verify plug-in(s), if registered */
+    if (SUCCESS != verify_cert_call_plugin(opt->plugins, opt->es, cert_depth, cert, subject))
+    {
+        goto cleanup;
+    }
+
+    /* run --tls-verify script */
+    if (opt->verify_command && SUCCESS != verify_cert_call_command(opt->verify_command,
+                                                                   opt->es, cert_depth, cert, subject, opt->verify_export_cert))
+    {
+        goto cleanup;
+    }
+
+    /* check peer cert against CRL */
+    if (opt->crl_file)
+    {
+        if (opt->ssl_flags & SSLF_CRL_VERIFY_DIR)
+        {
+            if (SUCCESS != verify_check_crl_dir(opt->crl_file, cert))
+            {
+                goto cleanup;
+            }
+        }
+        else
+        {
+            if (tls_verify_crl_missing(opt))
+            {
+                msg(D_TLS_ERRORS, "VERIFY ERROR: CRL not loaded");
+                goto cleanup;
+            }
+        }
+    }
+
+    msg(D_HANDSHAKE, "VERIFY OK: depth=%d, %s", cert_depth, subject);
+    session->verified = true;
+    ret = SUCCESS;
+
+cleanup:
+
+    if (ret != SUCCESS)
+    {
+        tls_clear_error(); /* always? */
+        session->verified = false; /* double sure? */
+    }
+    gc_free(&gc);
+
+    return ret;
+}
+
+/* ***************************************************************************
+* Functions for the management of deferred authentication when using
+* user/password authentication.
+*************************************************************************** */
+
+#ifdef ENABLE_DEF_AUTH
+/* key_state_test_auth_control_file return values,
+ * NOTE: acf_merge indexing depends on these values */
+#define ACF_UNDEFINED 0
+#define ACF_SUCCEEDED 1
+#define ACF_DISABLED  2
+#define ACF_FAILED    3
+#endif
+
+#ifdef MANAGEMENT_DEF_AUTH
+void
+man_def_auth_set_client_reason(struct tls_multi *multi, const char *client_reason)
+{
+    if (multi->client_reason)
+    {
+        free(multi->client_reason);
+        multi->client_reason = NULL;
+    }
+    if (client_reason && strlen(client_reason))
+    {
+        /* FIXME: Last alloc will never be freed */
+        multi->client_reason = string_alloc(client_reason, NULL);
+    }
+}
+
+static inline unsigned int
+man_def_auth_test(const struct key_state *ks)
+{
+    if (management_enable_def_auth(management))
+    {
+        return ks->mda_status;
+    }
+    else
+    {
+        return ACF_DISABLED;
+    }
+}
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+
+#ifdef PLUGIN_DEF_AUTH
+
+/*
+ * auth_control_file functions
+ */
+
+void
+key_state_rm_auth_control_file(struct key_state *ks)
+{
+    if (ks && ks->auth_control_file)
+    {
+        platform_unlink(ks->auth_control_file);
+        free(ks->auth_control_file);
+        ks->auth_control_file = NULL;
+    }
+}
+
+static bool
+key_state_gen_auth_control_file(struct key_state *ks, const struct tls_options *opt)
+{
+    struct gc_arena gc = gc_new();
+
+    key_state_rm_auth_control_file(ks);
+    const char *acf = create_temp_file(opt->tmp_dir, "acf", &gc);
+    if (acf)
+    {
+        ks->auth_control_file = string_alloc(acf, NULL);
+        setenv_str(opt->es, "auth_control_file", ks->auth_control_file);
+    }
+
+    gc_free(&gc);
+    return acf;
+}
+
+static unsigned int
+key_state_test_auth_control_file(struct key_state *ks)
+{
+    if (ks && ks->auth_control_file)
+    {
+        unsigned int ret = ks->auth_control_status;
+        if (ret == ACF_UNDEFINED)
+        {
+            FILE *fp = fopen(ks->auth_control_file, "r");
+            if (fp)
+            {
+                const int c = fgetc(fp);
+                if (c == '1')
+                {
+                    ret = ACF_SUCCEEDED;
+                }
+                else if (c == '0')
+                {
+                    ret = ACF_FAILED;
+                }
+                fclose(fp);
+                ks->auth_control_status = ret;
+            }
+        }
+        return ret;
+    }
+    return ACF_DISABLED;
+}
+
+#endif /* ifdef PLUGIN_DEF_AUTH */
+
+/*
+ * Return current session authentication state.  Return
+ * value is TLS_AUTHENTICATION_x.
+ */
+
+int
+tls_authentication_status(struct tls_multi *multi, const int latency)
+{
+    bool deferred = false;
+    bool success = false;
+    bool active = false;
+
+#ifdef ENABLE_DEF_AUTH
+    static const unsigned char acf_merge[] =
+    {
+        ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_UNDEFINED */
+        ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_SUCCEEDED */
+        ACF_UNDEFINED, /* s1=ACF_UNDEFINED s2=ACF_DISABLED */
+        ACF_FAILED,  /* s1=ACF_UNDEFINED s2=ACF_FAILED */
+        ACF_UNDEFINED, /* s1=ACF_SUCCEEDED s2=ACF_UNDEFINED */
+        ACF_SUCCEEDED, /* s1=ACF_SUCCEEDED s2=ACF_SUCCEEDED */
+        ACF_SUCCEEDED, /* s1=ACF_SUCCEEDED s2=ACF_DISABLED */
+        ACF_FAILED,  /* s1=ACF_SUCCEEDED s2=ACF_FAILED */
+        ACF_UNDEFINED, /* s1=ACF_DISABLED  s2=ACF_UNDEFINED */
+        ACF_SUCCEEDED, /* s1=ACF_DISABLED  s2=ACF_SUCCEEDED */
+        ACF_DISABLED, /* s1=ACF_DISABLED  s2=ACF_DISABLED */
+        ACF_FAILED,  /* s1=ACF_DISABLED  s2=ACF_FAILED */
+        ACF_FAILED,  /* s1=ACF_FAILED    s2=ACF_UNDEFINED */
+        ACF_FAILED,  /* s1=ACF_FAILED    s2=ACF_SUCCEEDED */
+        ACF_FAILED,  /* s1=ACF_FAILED    s2=ACF_DISABLED */
+        ACF_FAILED   /* s1=ACF_FAILED    s2=ACF_FAILED */
+    };
+#endif /* ENABLE_DEF_AUTH */
+
+    if (multi)
+    {
+        int i;
+
+#ifdef ENABLE_DEF_AUTH
+        if (latency && multi->tas_last && multi->tas_last + latency >= now)
+        {
+            return TLS_AUTHENTICATION_UNDEFINED;
+        }
+        multi->tas_last = now;
+#endif /* ENABLE_DEF_AUTH */
+
+        for (i = 0; i < KEY_SCAN_SIZE; ++i)
+        {
+            struct key_state *ks = multi->key_scan[i];
+            if (DECRYPT_KEY_ENABLED(multi, ks))
+            {
+                active = true;
+                if (ks->authenticated)
+                {
+#ifdef ENABLE_DEF_AUTH
+                    unsigned int s1 = ACF_DISABLED;
+                    unsigned int s2 = ACF_DISABLED;
+#ifdef PLUGIN_DEF_AUTH
+                    s1 = key_state_test_auth_control_file(ks);
+#endif /* PLUGIN_DEF_AUTH */
+#ifdef MANAGEMENT_DEF_AUTH
+                    s2 = man_def_auth_test(ks);
+#endif /* MANAGEMENT_DEF_AUTH */
+                    ASSERT(s1 < 4 && s2 < 4);
+                    switch (acf_merge[(s1<<2) + s2])
+                    {
+                        case ACF_SUCCEEDED:
+                        case ACF_DISABLED:
+                            success = true;
+                            ks->auth_deferred = false;
+                            break;
+
+                        case ACF_UNDEFINED:
+                            if (now < ks->auth_deferred_expire)
+                            {
+                                deferred = true;
+                            }
+                            break;
+
+                        case ACF_FAILED:
+                            ks->authenticated = false;
+                            break;
+
+                        default:
+                            ASSERT(0);
+                    }
+#else /* !ENABLE_DEF_AUTH */
+                    success = true;
+#endif /* ENABLE_DEF_AUTH */
+                }
+            }
+        }
+    }
+
+#if 0
+    dmsg(D_TLS_ERRORS, "TAS: a=%d s=%d d=%d", active, success, deferred);
+#endif
+
+    if (success)
+    {
+        return TLS_AUTHENTICATION_SUCCEEDED;
+    }
+    else if (!active || deferred)
+    {
+        return TLS_AUTHENTICATION_DEFERRED;
+    }
+    else
+    {
+        return TLS_AUTHENTICATION_FAILED;
+    }
+}
+
+#ifdef MANAGEMENT_DEF_AUTH
+/*
+ * For deferred auth, this is where the management interface calls (on server)
+ * to indicate auth failure/success.
+ */
+bool
+tls_authenticate_key(struct tls_multi *multi, const unsigned int mda_key_id, const bool auth, const char *client_reason)
+{
+    bool ret = false;
+    if (multi)
+    {
+        int i;
+        man_def_auth_set_client_reason(multi, client_reason);
+        for (i = 0; i < KEY_SCAN_SIZE; ++i)
+        {
+            struct key_state *ks = multi->key_scan[i];
+            if (ks->mda_key_id == mda_key_id)
+            {
+                ks->mda_status = auth ? ACF_SUCCEEDED : ACF_FAILED;
+                ret = true;
+            }
+        }
+    }
+    return ret;
+}
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+
+
+/* ****************************************************************************
+ * Functions to verify username and password
+ *
+ * Authenticate a client using username/password.
+ * Runs on server.
+ *
+ * If you want to add new authentication methods,
+ * this is the place to start.
+ *************************************************************************** */
+
+/*
+ * Verify the user name and password using a script
+ */
+static bool
+verify_user_pass_script(struct tls_session *session, const struct user_pass *up)
+{
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+    const char *tmp_file = "";
+    bool ret = false;
+
+    /* Is username defined? */
+    if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen(up->username))
+    {
+        /* Set environmental variables prior to calling script */
+        setenv_str(session->opt->es, "script_type", "user-pass-verify");
+
+        if (session->opt->auth_user_pass_verify_script_via_file)
+        {
+            struct status_output *so;
+
+            tmp_file = create_temp_file(session->opt->tmp_dir, "up", &gc);
+            if (tmp_file)
+            {
+                so = status_open(tmp_file, 0, -1, NULL, STATUS_OUTPUT_WRITE);
+                status_printf(so, "%s", up->username);
+                status_printf(so, "%s", up->password);
+                if (!status_close(so))
+                {
+                    msg(D_TLS_ERRORS, "TLS Auth Error: could not write username/password to file: %s",
+                        tmp_file);
+                    goto done;
+                }
+            }
+            else
+            {
+                msg(D_TLS_ERRORS, "TLS Auth Error: could not create write "
+                    "username/password to temp file");
+            }
+        }
+        else
+        {
+            setenv_str(session->opt->es, "username", up->username);
+            setenv_str(session->opt->es, "password", up->password);
+        }
+
+        /* setenv incoming cert common name for script */
+        setenv_str(session->opt->es, "common_name", session->common_name);
+
+        /* setenv client real IP address */
+        setenv_untrusted(session);
+
+        /* format command line */
+        argv_parse_cmd(&argv, session->opt->auth_user_pass_verify_script);
+        argv_printf_cat(&argv, "%s", tmp_file);
+
+        /* call command */
+        ret = openvpn_run_script(&argv, session->opt->es, 0,
+                                 "--auth-user-pass-verify");
+
+        if (!session->opt->auth_user_pass_verify_script_via_file)
+        {
+            setenv_del(session->opt->es, "password");
+        }
+    }
+    else
+    {
+        msg(D_TLS_ERRORS, "TLS Auth Error: peer provided a blank username");
+    }
+
+done:
+    if (tmp_file && strlen(tmp_file) > 0)
+    {
+        platform_unlink(tmp_file);
+    }
+
+    argv_reset(&argv);
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Verify the username and password using a plugin
+ */
+static int
+verify_user_pass_plugin(struct tls_session *session, const struct user_pass *up, const char *raw_username)
+{
+    int retval = OPENVPN_PLUGIN_FUNC_ERROR;
+#ifdef PLUGIN_DEF_AUTH
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+#endif
+
+    /* Is username defined? */
+    if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen(up->username))
+    {
+        /* set username/password in private env space */
+        setenv_str(session->opt->es, "username", (raw_username ? raw_username : up->username));
+        setenv_str(session->opt->es, "password", up->password);
+
+        /* setenv incoming cert common name for script */
+        setenv_str(session->opt->es, "common_name", session->common_name);
+
+        /* setenv client real IP address */
+        setenv_untrusted(session);
+
+#ifdef PLUGIN_DEF_AUTH
+        /* generate filename for deferred auth control file */
+        if (!key_state_gen_auth_control_file(ks, session->opt))
+        {
+            msg (D_TLS_ERRORS, "TLS Auth Error (%s): "
+                 "could not create deferred auth control file", __func__);
+            goto cleanup;
+        }
+#endif
+
+        /* call command */
+        retval = plugin_call(session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY, NULL, NULL, session->opt->es);
+
+#ifdef PLUGIN_DEF_AUTH
+        /* purge auth control filename (and file itself) for non-deferred returns */
+        if (retval != OPENVPN_PLUGIN_FUNC_DEFERRED)
+        {
+            key_state_rm_auth_control_file(ks);
+        }
+#endif
+
+        setenv_del(session->opt->es, "password");
+        if (raw_username)
+        {
+            setenv_str(session->opt->es, "username", up->username);
+        }
+    }
+    else
+    {
+        msg(D_TLS_ERRORS, "TLS Auth Error (verify_user_pass_plugin): peer provided a blank username");
+    }
+
+cleanup:
+    return retval;
+}
+
+
+#ifdef MANAGEMENT_DEF_AUTH
+/*
+ * MANAGEMENT_DEF_AUTH internal ssl_verify.c status codes
+ */
+#define KMDA_ERROR   0
+#define KMDA_SUCCESS 1
+#define KMDA_UNDEF   2
+#define KMDA_DEF     3
+
+static int
+verify_user_pass_management(struct tls_session *session, const struct user_pass *up, const char *raw_username)
+{
+    int retval = KMDA_ERROR;
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    /* Is username defined? */
+    if ((session->opt->ssl_flags & SSLF_AUTH_USER_PASS_OPTIONAL) || strlen(up->username))
+    {
+        /* set username/password in private env space */
+        setenv_str(session->opt->es, "username", (raw_username ? raw_username : up->username));
+        setenv_str(session->opt->es, "password", up->password);
+
+        /* setenv incoming cert common name for script */
+        setenv_str(session->opt->es, "common_name", session->common_name);
+
+        /* setenv client real IP address */
+        setenv_untrusted(session);
+
+        if (management)
+        {
+            management_notify_client_needing_auth(management, ks->mda_key_id, session->opt->mda_context, session->opt->es);
+        }
+
+        setenv_del(session->opt->es, "password");
+        if (raw_username)
+        {
+            setenv_str(session->opt->es, "username", up->username);
+        }
+
+        retval = KMDA_SUCCESS;
+    }
+    else
+    {
+        msg(D_TLS_ERRORS, "TLS Auth Error (verify_user_pass_management): peer provided a blank username");
+    }
+
+    return retval;
+}
+#endif /* ifdef MANAGEMENT_DEF_AUTH */
+
+/*
+ * Main username/password verification entry point
+ */
+void
+verify_user_pass(struct user_pass *up, struct tls_multi *multi,
+                 struct tls_session *session)
+{
+    int s1 = OPENVPN_PLUGIN_FUNC_SUCCESS;
+    bool s2 = true;
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    struct gc_arena gc = gc_new();
+    char *raw_username = NULL;
+
+#ifdef MANAGEMENT_DEF_AUTH
+    int man_def_auth = KMDA_UNDEF;
+
+    if (management_enable_def_auth(management))
+    {
+        man_def_auth = KMDA_DEF;
+    }
+#endif
+
+    /*
+     * Preserve the raw username before string_mod remapping, for plugins
+     * and management clients when in --compat-names mode
+     */
+    if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NAMES))
+    {
+        ALLOC_ARRAY_CLEAR_GC(raw_username, char, USER_PASS_LEN, &gc);
+        strcpy(raw_username, up->username);
+        string_mod(raw_username, CC_PRINT, CC_CRLF, '_');
+    }
+
+    /* enforce character class restrictions in username/password */
+    string_mod_remap_name(up->username, COMMON_NAME_CHAR_CLASS);
+    string_mod(up->password, CC_PRINT, CC_CRLF, '_');
+
+    /* If server is configured with --auth-gen-token and we have an
+     * authentication token for this client, this authentication
+     * round will be done internally using the token instead of
+     * calling any external authentication modules.
+     */
+    if (session->opt->auth_token_generate && multi->auth_token_sent
+        && NULL != multi->auth_token)
+    {
+        unsigned int ssl_flags = session->opt->ssl_flags;
+
+        /* Ensure that the username has not changed */
+        if (!tls_lock_username(multi, up->username))
+        {
+            /* auth-token cleared in tls_lock_username() on failure */
+            ks->authenticated = false;
+            goto done;
+        }
+
+        /* If auth-token lifetime has been enabled,
+         * ensure the token has not expired
+         */
+        if (session->opt->auth_token_lifetime > 0
+            && (multi->auth_token_tstamp + session->opt->auth_token_lifetime) < now)
+        {
+            msg(D_HANDSHAKE, "Auth-token for client expired\n");
+            wipe_auth_token(multi);
+            ks->authenticated = false;
+            goto done;
+        }
+
+        /* The core authentication of the token itself */
+        if (memcmp_constant_time(multi->auth_token, up->password,
+                                 strlen(multi->auth_token)) != 0)
+        {
+            ks->authenticated = false;
+            tls_deauthenticate(multi);
+
+            msg(D_TLS_ERRORS, "TLS Auth Error: Auth-token verification "
+                "failed for username '%s' %s", up->username,
+                (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
+        }
+        else
+        {
+            ks->authenticated = true;
+
+            if (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME)
+            {
+                set_common_name(session, up->username);
+            }
+            msg(D_HANDSHAKE, "TLS: Username/auth-token authentication "
+                "succeeded for username '%s' %s",
+                up->username,
+                (ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
+        }
+        goto done;
+    }
+
+    /* call plugin(s) and/or script */
+#ifdef MANAGEMENT_DEF_AUTH
+    if (man_def_auth == KMDA_DEF)
+    {
+        man_def_auth = verify_user_pass_management(session, up, raw_username);
+    }
+#endif
+    if (plugin_defined(session->opt->plugins, OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY))
+    {
+        s1 = verify_user_pass_plugin(session, up, raw_username);
+    }
+    if (session->opt->auth_user_pass_verify_script)
+    {
+        s2 = verify_user_pass_script(session, up);
+    }
+
+    /* check sizing of username if it will become our common name */
+    if ((session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) && strlen(up->username) > TLS_USERNAME_LEN)
+    {
+        msg(D_TLS_ERRORS, "TLS Auth Error: --username-as-common name specified and username is longer than the maximum permitted Common Name length of %d characters", TLS_USERNAME_LEN);
+        s1 = OPENVPN_PLUGIN_FUNC_ERROR;
+    }
+
+    /* auth succeeded? */
+    if ((s1 == OPENVPN_PLUGIN_FUNC_SUCCESS
+#ifdef PLUGIN_DEF_AUTH
+         || s1 == OPENVPN_PLUGIN_FUNC_DEFERRED
+#endif
+         ) && s2
+#ifdef MANAGEMENT_DEF_AUTH
+        && man_def_auth != KMDA_ERROR
+#endif
+        && tls_lock_username(multi, up->username))
+    {
+        ks->authenticated = true;
+#ifdef PLUGIN_DEF_AUTH
+        if (s1 == OPENVPN_PLUGIN_FUNC_DEFERRED)
+        {
+            ks->auth_deferred = true;
+        }
+#endif
+#ifdef MANAGEMENT_DEF_AUTH
+        if (man_def_auth != KMDA_UNDEF)
+        {
+            ks->auth_deferred = true;
+        }
+#endif
+
+        if ((session->opt->auth_token_generate) && (NULL == multi->auth_token))
+        {
+            /* Server is configured with --auth-gen-token but no token has yet
+             * been generated for this client.  Generate one and save it.
+             */
+            uint8_t tok[AUTH_TOKEN_SIZE];
+
+            if (!rand_bytes(tok, AUTH_TOKEN_SIZE))
+            {
+                msg( M_FATAL, "Failed to get enough randomness for "
+                     "authentication token");
+            }
+
+            /* The token should be longer than the input when
+             * being base64 encoded
+             */
+            ASSERT(openvpn_base64_encode(tok, AUTH_TOKEN_SIZE,
+                                         &multi->auth_token) > AUTH_TOKEN_SIZE);
+            multi->auth_token_tstamp = now;
+            dmsg(D_SHOW_KEYS, "Generated token for client: %s",
+                 multi->auth_token);
+        }
+
+        if ((session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME))
+        {
+            set_common_name(session, up->username);
+        }
+
+#ifdef ENABLE_DEF_AUTH
+        msg(D_HANDSHAKE, "TLS: Username/Password authentication %s for username '%s' %s",
+            ks->auth_deferred ? "deferred" : "succeeded",
+            up->username,
+            (session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
+#else
+        msg(D_HANDSHAKE, "TLS: Username/Password authentication %s for username '%s' %s",
+            "succeeded",
+            up->username,
+            (session->opt->ssl_flags & SSLF_USERNAME_AS_COMMON_NAME) ? "[CN SET]" : "");
+#endif
+    }
+    else
+    {
+        msg(D_TLS_ERRORS, "TLS Auth Error: Auth Username/Password verification failed for peer");
+    }
+
+done:
+    gc_free(&gc);
+}
+
+void
+verify_final_auth_checks(struct tls_multi *multi, struct tls_session *session)
+{
+    struct key_state *ks = &session->key[KS_PRIMARY];      /* primary key */
+
+    /* While it shouldn't really happen, don't allow the common name to be NULL */
+    if (!session->common_name)
+    {
+        set_common_name(session, "");
+    }
+
+    /* Don't allow the CN to change once it's been locked */
+    if (ks->authenticated && multi->locked_cn)
+    {
+        const char *cn = session->common_name;
+        if (cn && strcmp(cn, multi->locked_cn))
+        {
+            msg(D_TLS_ERRORS, "TLS Auth Error: TLS object CN attempted to change from '%s' to '%s' -- tunnel disabled",
+                multi->locked_cn,
+                cn);
+
+            /* change the common name back to its original value and disable the tunnel */
+            set_common_name(session, multi->locked_cn);
+            tls_deauthenticate(multi);
+        }
+    }
+
+    /* Don't allow the cert hashes to change once they have been locked */
+    if (ks->authenticated && multi->locked_cert_hash_set)
+    {
+        const struct cert_hash_set *chs = session->cert_hash_set;
+        if (chs && !cert_hash_compare(chs, multi->locked_cert_hash_set))
+        {
+            msg(D_TLS_ERRORS, "TLS Auth Error: TLS object CN=%s client-provided SSL certs unexpectedly changed during mid-session reauth",
+                session->common_name);
+
+            /* disable the tunnel */
+            tls_deauthenticate(multi);
+        }
+    }
+
+    /* verify --client-config-dir based authentication */
+    if (ks->authenticated && session->opt->client_config_dir_exclusive)
+    {
+        struct gc_arena gc = gc_new();
+
+        const char *cn = session->common_name;
+        const char *path = gen_path(session->opt->client_config_dir_exclusive, cn, &gc);
+        if (!cn || !strcmp(cn, CCD_DEFAULT) || !test_file(path))
+        {
+            ks->authenticated = false;
+            wipe_auth_token(multi);
+            msg(D_TLS_ERRORS, "TLS Auth Error: --client-config-dir authentication failed for common name '%s' file='%s'",
+                session->common_name,
+                path ? path : "UNDEF");
+        }
+
+        gc_free(&gc);
+    }
+}
+
+void
+tls_x509_clear_env(struct env_set *es)
+{
+    struct env_item *item = es->list;
+    while (item)
+    {
+        struct env_item *next = item->next;
+        if (item->string
+            && 0 == strncmp("X509_", item->string, strlen("X509_")))
+        {
+            env_set_del(es, item->string);
+        }
+        item = next;
+    }
+}
+
+#endif /* ENABLE_CRYPTO */
diff --git a/src/openvpn/ssl_verify.h b/src/openvpn/ssl_verify.h
new file mode 100644
index 0000000..3e2267a
--- /dev/null
+++ b/src/openvpn/ssl_verify.h
@@ -0,0 +1,248 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module
+ */
+
+#ifndef SSL_VERIFY_H_
+#define SSL_VERIFY_H_
+
+#ifdef ENABLE_CRYPTO
+
+#include "syshead.h"
+#include "misc.h"
+#include "ssl_common.h"
+
+/* Include OpenSSL-specific code */
+#ifdef ENABLE_CRYPTO_OPENSSL
+#include "ssl_verify_openssl.h"
+#endif
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#include "ssl_verify_mbedtls.h"
+#endif
+
+#include "ssl_verify_backend.h"
+
+/*
+ * Keep track of certificate hashes at various depths
+ */
+
+/** Maximum certificate depth we will allow */
+#define MAX_CERT_DEPTH 16
+
+/** Structure containing the hash for a single certificate */
+struct cert_hash {
+    unsigned char sha256_hash[256/8];
+};
+
+/** Structure containing the hashes for a full certificate chain */
+struct cert_hash_set {
+    struct cert_hash *ch[MAX_CERT_DEPTH]; /**< Array of certificate hashes */
+};
+
+#define VERIFY_X509_NONE                0
+#define VERIFY_X509_SUBJECT_DN          1
+#define VERIFY_X509_SUBJECT_RDN         2
+#define VERIFY_X509_SUBJECT_RDN_PREFIX  3
+
+#define TLS_AUTHENTICATION_SUCCEEDED  0
+#define TLS_AUTHENTICATION_FAILED     1
+#define TLS_AUTHENTICATION_DEFERRED   2
+#define TLS_AUTHENTICATION_UNDEFINED  3
+
+/*
+ * Return current session authentication state.  Return
+ * value is TLS_AUTHENTICATION_x.
+ *
+ * TODO: document this function
+ */
+int tls_authentication_status(struct tls_multi *multi, const int latency);
+
+/** Check whether the \a ks \c key_state is ready to receive data channel
+ *   packets.
+ *   @ingroup data_crypto
+ *
+ *   If true, it is safe to assume that this session has been authenticated
+ *   by TLS.
+ *
+ *   @note This macro only works if S_SENT_KEY + 1 == S_GOT_KEY. */
+#define DECRYPT_KEY_ENABLED(multi, ks) ((ks)->state >= (S_GOT_KEY - (multi)->opt.server))
+
+/**
+ * Remove the given key state's auth control file, if it exists.
+ *
+ * @param ks    The key state the remove the file for
+ */
+void key_state_rm_auth_control_file(struct key_state *ks);
+
+/**
+ * Frees the given set of certificate hashes.
+ *
+ * @param chs   The certificate hash set to free.
+ */
+void cert_hash_free(struct cert_hash_set *chs);
+
+/**
+ * Locks the certificate hash set used in the given tunnel
+ *
+ * @param multi The tunnel to lock
+ */
+void tls_lock_cert_hash_set(struct tls_multi *multi);
+
+/**
+ * Locks the common name field for the given tunnel
+ *
+ * @param multi The tunnel to lock
+ */
+void tls_lock_common_name(struct tls_multi *multi);
+
+/**
+ * Returns the common name field for the given tunnel
+ *
+ * @param multi The tunnel to return the common name for
+ * @param null  Whether null may be returned. If not, "UNDEF" will be returned.
+ */
+const char *tls_common_name(const struct tls_multi *multi, const bool null);
+
+/**
+ * Returns the username field for the given tunnel
+ *
+ * @param multi The tunnel to return the username for
+ * @param null  Whether null may be returned. If not, "UNDEF" will be returned.
+ */
+const char *tls_username(const struct tls_multi *multi, const bool null);
+
+/**
+ * Compares certificates hashes, returns true if hashes are equal.
+ *
+ * @param chs1 cert 1 hash set
+ * @param chs2 cert 2 hash set
+ */
+bool cert_hash_compare(const struct cert_hash_set *chs1, const struct cert_hash_set *chs2);
+
+#ifdef ENABLE_PF
+
+/**
+ * Retrieve the given tunnel's common name and its hash value.
+ *
+ * @param multi         The tunnel to use
+ * @param cn            Common name's string
+ * @param cn_hash       Common name's hash value
+ *
+ * @return true if the common name was set, false otherwise.
+ */
+static inline bool
+tls_common_name_hash(const struct tls_multi *multi, const char **cn, uint32_t *cn_hash)
+{
+    if (multi)
+    {
+        const struct tls_session *s = &multi->session[TM_ACTIVE];
+        if (s->common_name && s->common_name[0] != '\0')
+        {
+            *cn = s->common_name;
+            *cn_hash = s->common_name_hashval;
+            return true;
+        }
+    }
+    return false;
+}
+
+#endif
+
+/**
+ * Verify the given username and password, using either an external script, a
+ * plugin, or the management interface.
+ *
+ * If authentication succeeds, the appropriate state is filled into the
+ * session's primary key state's authenticated field. Authentication may also
+ * be deferred, in which case the key state's auth_deferred field is filled in.
+ *
+ * @param up            The username and password to verify.
+ * @param multi         The TLS multi structure to verify usernames against.
+ * @param session       The current TLS session
+ *
+ */
+void verify_user_pass(struct user_pass *up, struct tls_multi *multi,
+                      struct tls_session *session);
+
+/**
+ * Perform final authentication checks, including locking of the cn, the allowed
+ * certificate hashes, and whether a client config entry exists in the
+ * client config directory.
+ *
+ * @param multi         The TLS multi structure to verify locked structures.
+ * @param session       The current TLS session
+ *
+ */
+void verify_final_auth_checks(struct tls_multi *multi, struct tls_session *session);
+
+struct x509_track
+{
+    const struct x509_track *next;
+    const char *name;
+#define XT_FULL_CHAIN (1<<0)
+    unsigned int flags;
+    int nid;
+};
+
+/*
+ * Certificate checking for verify_nsCertType
+ */
+/** Do not perform Netscape certificate type verification */
+#define NS_CERT_CHECK_NONE (0)
+/** Do not perform Netscape certificate type verification */
+#define NS_CERT_CHECK_SERVER (1<<0)
+/** Do not perform Netscape certificate type verification */
+#define NS_CERT_CHECK_CLIENT (1<<1)
+
+/** Require keyUsage to be present in cert (0xFFFF is an invalid KU value) */
+#define OPENVPN_KU_REQUIRED (0xFFFF)
+
+/*
+ * TODO: document
+ */
+#ifdef MANAGEMENT_DEF_AUTH
+bool tls_authenticate_key(struct tls_multi *multi, const unsigned int mda_key_id, const bool auth, const char *client_reason);
+
+void man_def_auth_set_client_reason(struct tls_multi *multi, const char *client_reason);
+
+#endif
+
+static inline const char *
+tls_client_reason(struct tls_multi *multi)
+{
+#ifdef ENABLE_DEF_AUTH
+    return multi->client_reason;
+#else
+    return NULL;
+#endif
+}
+
+/** Remove any X509_ env variables from env_set es */
+void tls_x509_clear_env(struct env_set *es);
+
+#endif /* ENABLE_CRYPTO */
+
+#endif /* SSL_VERIFY_H_ */
diff --git a/src/openvpn/ssl_verify_backend.h b/src/openvpn/ssl_verify_backend.h
new file mode 100644
index 0000000..2a9e8bb
--- /dev/null
+++ b/src/openvpn/ssl_verify_backend.h
@@ -0,0 +1,270 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module library-specific backend interface
+ */
+
+#ifndef SSL_VERIFY_BACKEND_H_
+#define SSL_VERIFY_BACKEND_H_
+
+/**
+ * Result of verification function
+ */
+typedef enum { SUCCESS = 0, FAILURE = 1 } result_t;
+
+/*
+ * Backend support functions.
+ *
+ * The following functions are needed by the backend, but defined in the main
+ * file.
+ */
+
+/*
+ * Verify certificate for the given session. Performs OpenVPN-specific
+ * verification.
+ *
+ * This function must be called for every certificate in the certificate
+ * chain during the certificate verification stage of the handshake.
+ *
+ * @param session       TLS Session associated with this tunnel
+ * @param cert          Certificate to process
+ * @param cert_depth    Depth of the current certificate
+ *
+ * @return              \c SUCCESS if verification was successful, \c FAILURE on failure.
+ */
+result_t verify_cert(struct tls_session *session, openvpn_x509_cert_t *cert, int cert_depth);
+
+/*
+ * Remember the given certificate hash, allowing the certificate chain to be
+ * locked between sessions.
+ *
+ * Must be called for every certificate in the verification chain, whether it
+ * is valid or not.
+ *
+ * @param session       TLS Session associated with this tunnel
+ * @param cert_depth    Depth of the current certificate
+ * @param cert_hash     Hash of the current certificate
+ */
+void cert_hash_remember(struct tls_session *session, const int cert_depth,
+                        const struct buffer *cert_hash);
+
+/*
+ * Library-specific functions.
+ *
+ * The following functions must be implemented on a library-specific basis.
+ */
+
+/*
+ * Retrieve certificate's subject name.
+ *
+ * @param cert          Certificate to retrieve the subject from.
+ * @param gc            Garbage collection arena to use when allocating string.
+ *
+ * @return              a string containing the subject
+ */
+char *x509_get_subject(openvpn_x509_cert_t *cert, struct gc_arena *gc);
+
+/**
+ * Retrieve the certificate's SHA1 fingerprint.
+ *
+ * @param cert          Certificate to retrieve the fingerprint from.
+ * @param gc            Garbage collection arena to use when allocating string.
+ *
+ * @return              a string containing the certificate fingerprint
+ */
+struct buffer x509_get_sha1_fingerprint(openvpn_x509_cert_t *cert,
+                                        struct gc_arena *gc);
+
+/**
+ * Retrieve the certificate's SHA256 fingerprint.
+ *
+ * @param cert          Certificate to retrieve the fingerprint from.
+ * @param gc            Garbage collection arena to use when allocating string.
+ *
+ * @return              a string containing the certificate fingerprint
+ */
+struct buffer x509_get_sha256_fingerprint(openvpn_x509_cert_t *cert,
+                                          struct gc_arena *gc);
+
+/*
+ * Retrieve the certificate's username from the specified field.
+ *
+ * If the field is prepended with ext: and ENABLE_X509ALTUSERNAME is enabled,
+ * it will be loaded from an X.509 extension
+ *
+ * @param cn                    Buffer to return the common name in.
+ * @param cn_len                Length of the cn buffer.
+ * @param x509_username_field   Name of the field to load from
+ * @param cert                  Certificate to retrieve the common name from.
+ *
+ * @return              \c FAILURE, \c or SUCCESS
+ */
+result_t backend_x509_get_username(char *common_name, int cn_len,
+                                   char *x509_username_field, openvpn_x509_cert_t *peer_cert);
+
+#ifdef ENABLE_X509ALTUSERNAME
+/**
+ * Return true iff the supplied extension field is supported by the
+ * --x509-username-field option.
+ */
+bool x509_username_field_ext_supported(const char *extname);
+#endif
+
+/*
+ * Return the certificate's serial number in decimal string representation.
+ *
+ * The serial number is returned as a string, since it might be a bignum.
+ *
+ * @param cert          Certificate to retrieve the serial number from.
+ * @param gc            Garbage collection arena to use when allocating string.
+ *
+ * @return              String representation of the certificate's serial number
+ *                      in decimal notation, or NULL on error.
+ */
+char *backend_x509_get_serial(openvpn_x509_cert_t *cert, struct gc_arena *gc);
+
+/*
+ * Return the certificate's serial number in hex string representation.
+ *
+ * The serial number is returned as a string, since it might be a bignum.
+ *
+ * @param cert          Certificate to retrieve the serial number from.
+ * @param gc            Garbage collection arena to use when allocating string.
+ *
+ * @return              String representation of the certificate's serial number
+ *                      in hex notation, or NULL on error.
+ */
+char *backend_x509_get_serial_hex(openvpn_x509_cert_t *cert,
+                                  struct gc_arena *gc);
+
+/*
+ * Save X509 fields to environment, using the naming convention:
+ *
+ * X509_{cert_depth}_{name}={value}
+ *
+ * @param es            Environment set to save variables in
+ * @param cert_depth    Depth of the certificate
+ * @param cert          Certificate to set the environment for
+ */
+void x509_setenv(struct env_set *es, int cert_depth, openvpn_x509_cert_t *cert);
+
+/*
+ * Start tracking the given attribute.
+ *
+ * The tracked attributes are stored in ll_head.
+ *
+ * @param ll_head       The x509_track to store tracked atttributes in
+ * @param name          Name of the attribute to track
+ * @param msglevel      Message level for errors
+ * @param gc            Garbage collection arena for temp data
+ *
+ */
+void x509_track_add(const struct x509_track **ll_head, const char *name,
+                    int msglevel, struct gc_arena *gc);
+
+/*
+ * Save X509 fields to environment, using the naming convention:
+ *
+ *  X509_{cert_depth}_{name}={value}
+ *
+ * This function differs from setenv_x509 below in the following ways:
+ *
+ * (1) Only explicitly named attributes in xt are saved, per usage
+ *     of --x509-track program options.
+ * (2) Only the level 0 cert info is saved unless the XT_FULL_CHAIN
+ *     flag is set in xt->flags (corresponds with prepending a '+'
+ *     to the name when specified by --x509-track program option).
+ * (3) This function supports both X509 subject name fields as
+ *     well as X509 V3 extensions.
+ *
+ * @param xt
+ * @param es            Environment set to save variables in
+ * @param cert_depth    Depth of the certificate
+ * @param cert          Certificate to set the environment for
+ */
+void x509_setenv_track(const struct x509_track *xt, struct env_set *es,
+                       const int depth, openvpn_x509_cert_t *x509);
+
+/*
+ * Check X.509 Netscape certificate type field, if available.
+ *
+ * @param cert          Certificate to check.
+ * @param usage         One of \c NS_CERT_CHECK_CLIENT, \c NS_CERT_CHECK_SERVER,
+ *                      or \c NS_CERT_CHECK_NONE.
+ *
+ * @return              \c SUCCESS if NS_CERT_CHECK_NONE or if the certificate has
+ *                      the expected bit set. \c FAILURE if the certificate does
+ *                      not have NS cert type verification or the wrong bit set.
+ */
+result_t x509_verify_ns_cert_type(openvpn_x509_cert_t *cert, const int usage);
+
+/*
+ * Verify X.509 key usage extension field.
+ *
+ * @param cert          Certificate to check.
+ * @param expected_ku   Array of valid key usage values
+ * @param expected_len  Length of the key usage array
+ *
+ * @return              \c SUCCESS if one of the key usage values matches, \c FAILURE
+ *                      if key usage is not enabled, or the values do not match.
+ */
+result_t x509_verify_cert_ku(openvpn_x509_cert_t *x509, const unsigned *const expected_ku,
+                             int expected_len);
+
+/*
+ * Verify X.509 extended key usage extension field.
+ *
+ * @param cert          Certificate to check.
+ * @param expected_oid  String representation of the expected Object ID. May be
+ *                      either the string representation of the numeric OID
+ *                      (e.g. \c "1.2.3.4", or the descriptive string matching
+ *                      the OID.
+ *
+ * @return              \c SUCCESS if one of the expected OID matches one of the
+ *                      extended key usage fields, \c FAILURE if extended key
+ *                      usage is not enabled, or the values do not match.
+ */
+result_t x509_verify_cert_eku(openvpn_x509_cert_t *x509, const char *const expected_oid);
+
+/*
+ * Store the given certificate in pem format in a temporary file in tmp_dir
+ *
+ * @param cert          Certificate to store
+ * @param tmp_dir       Temporary directory to store the directory
+ * @param gc            gc_arena to store temporary objects in
+ *
+ *
+ */
+result_t x509_write_pem(FILE *peercert_file, openvpn_x509_cert_t *peercert);
+
+/**
+ * Return true iff a CRL is configured, but is not loaded.  This can be caused
+ * by e.g. a CRL parsing error, a missing CRL file or CRL file permission
+ * errors.  (These conditions are checked upon startup, but the CRL might be
+ * updated and reloaded during runtime.)
+ */
+bool tls_verify_crl_missing(const struct tls_options *opt);
+
+#endif /* SSL_VERIFY_BACKEND_H_ */
diff --git a/src/openvpn/ssl_verify_mbedtls.c b/src/openvpn/ssl_verify_mbedtls.c
new file mode 100644
index 0000000..2d019ab
--- /dev/null
+++ b/src/openvpn/ssl_verify_mbedtls.c
@@ -0,0 +1,553 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module mbed TLS backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "crypto_mbedtls.h"
+#include "ssl_verify.h"
+#include <mbedtls/asn1.h>
+#include <mbedtls/error.h>
+#include <mbedtls/bignum.h>
+#include <mbedtls/oid.h>
+#include <mbedtls/sha1.h>
+
+#define MAX_SUBJECT_LENGTH 256
+
+int
+verify_callback(void *session_obj, mbedtls_x509_crt *cert, int cert_depth,
+                uint32_t *flags)
+{
+    struct tls_session *session = (struct tls_session *) session_obj;
+    struct gc_arena gc = gc_new();
+
+    ASSERT(cert);
+    ASSERT(session);
+
+    session->verified = false;
+
+    /* Remember certificate hash */
+    struct buffer cert_fingerprint = x509_get_sha256_fingerprint(cert, &gc);
+    cert_hash_remember(session, cert_depth, &cert_fingerprint);
+
+    /* did peer present cert which was signed by our root cert? */
+    if (*flags != 0)
+    {
+        int ret = 0;
+        char errstr[512] = { 0 };
+        char *subject = x509_get_subject(cert, &gc);
+
+        ret = mbedtls_x509_crt_verify_info(errstr, sizeof(errstr)-1, "", *flags);
+        if (ret <= 0 && !openvpn_snprintf(errstr, sizeof(errstr),
+                                          "Could not retrieve error string, flags=%" PRIx32, *flags))
+        {
+            errstr[0] = '\0';
+        }
+        else
+        {
+            chomp(errstr);
+        }
+
+        if (subject)
+        {
+            msg(D_TLS_ERRORS, "VERIFY ERROR: depth=%d, subject=%s: %s",
+                cert_depth, subject, errstr);
+        }
+        else
+        {
+            msg(D_TLS_ERRORS, "VERIFY ERROR: depth=%d, (could not extract X509 "
+                "subject string from certificate): %s", cert_depth, errstr);
+        }
+
+        /* Leave flags set to non-zero to indicate that the cert is not ok */
+    }
+    else if (SUCCESS != verify_cert(session, cert, cert_depth))
+    {
+        *flags |= MBEDTLS_X509_BADCERT_OTHER;
+    }
+
+    gc_free(&gc);
+
+    /*
+     * PolarSSL/mbed TLS-1.2.0+ expects 0 on anything except fatal errors.
+     */
+    return 0;
+}
+
+#ifdef ENABLE_X509ALTUSERNAME
+#warning "X509 alt user name not yet supported for mbed TLS"
+#endif
+
+result_t
+backend_x509_get_username(char *cn, int cn_len,
+                          char *x509_username_field, mbedtls_x509_crt *cert)
+{
+    mbedtls_x509_name *name;
+
+    ASSERT( cn != NULL );
+
+    name = &cert->subject;
+
+    /* Find common name */
+    while (name != NULL)
+    {
+        if (0 == memcmp(name->oid.p, MBEDTLS_OID_AT_CN,
+                        MBEDTLS_OID_SIZE(MBEDTLS_OID_AT_CN)))
+        {
+            break;
+        }
+
+        name = name->next;
+    }
+
+    /* Not found, return an error if this is the peer's certificate */
+    if (name == NULL)
+    {
+        return FAILURE;
+    }
+
+    /* Found, extract CN */
+    if (cn_len > name->val.len)
+    {
+        memcpy( cn, name->val.p, name->val.len );
+        cn[name->val.len] = '\0';
+    }
+    else
+    {
+        memcpy( cn, name->val.p, cn_len);
+        cn[cn_len-1] = '\0';
+    }
+
+    return SUCCESS;
+}
+
+char *
+backend_x509_get_serial(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+    char *buf = NULL;
+    size_t buflen = 0;
+    mbedtls_mpi serial_mpi = { 0 };
+
+    /* Transform asn1 integer serial into mbed TLS MPI */
+    mbedtls_mpi_init(&serial_mpi);
+    if (!mbed_ok(mbedtls_mpi_read_binary(&serial_mpi, cert->serial.p,
+                                         cert->serial.len)))
+    {
+        msg(M_WARN, "Failed to retrieve serial from certificate.");
+        goto end;
+    }
+
+    /* Determine decimal representation length, allocate buffer */
+    mbedtls_mpi_write_string(&serial_mpi, 10, NULL, 0, &buflen);
+    buf = gc_malloc(buflen, true, gc);
+
+    /* Write MPI serial as decimal string into buffer */
+    if (!mbed_ok(mbedtls_mpi_write_string(&serial_mpi, 10, buf, buflen, &buflen)))
+    {
+        msg(M_WARN, "Failed to write serial to string.");
+        buf = NULL;
+        goto end;
+    }
+
+end:
+    mbedtls_mpi_free(&serial_mpi);
+    return buf;
+}
+
+char *
+backend_x509_get_serial_hex(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+    char *buf = NULL;
+    size_t len = cert->serial.len * 3 + 1;
+
+    buf = gc_malloc(len, true, gc);
+
+    if (mbedtls_x509_serial_gets(buf, len-1, &cert->serial) < 0)
+    {
+        buf = NULL;
+    }
+
+    return buf;
+}
+
+static struct buffer
+x509_get_fingerprint(const mbedtls_md_info_t *md_info, mbedtls_x509_crt *cert,
+                     struct gc_arena *gc)
+{
+    const size_t md_size = mbedtls_md_get_size(md_info);
+    struct buffer fingerprint = alloc_buf_gc(md_size, gc);
+    mbedtls_md(md_info, cert->raw.p, cert->raw.len, BPTR(&fingerprint));
+    ASSERT(buf_inc_len(&fingerprint, md_size));
+    return fingerprint;
+}
+
+struct buffer
+x509_get_sha1_fingerprint(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+    return x509_get_fingerprint(mbedtls_md_info_from_type(MBEDTLS_MD_SHA1),
+                                cert, gc);
+}
+
+struct buffer
+x509_get_sha256_fingerprint(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+    return x509_get_fingerprint(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
+                                cert, gc);
+}
+
+char *
+x509_get_subject(mbedtls_x509_crt *cert, struct gc_arena *gc)
+{
+    char tmp_subject[MAX_SUBJECT_LENGTH] = {0};
+    char *subject = NULL;
+
+    int ret = 0;
+
+    ret = mbedtls_x509_dn_gets( tmp_subject, MAX_SUBJECT_LENGTH-1, &cert->subject );
+    if (ret > 0)
+    {
+        /* Allocate the required space for the subject */
+        subject = string_alloc(tmp_subject, gc);
+    }
+
+    return subject;
+}
+
+static void
+do_setenv_x509(struct env_set *es, const char *name, char *value, int depth)
+{
+    char *name_expand;
+    size_t name_expand_size;
+
+    string_mod(value, CC_ANY, CC_CRLF, '?');
+    msg(D_X509_ATTR, "X509 ATTRIBUTE name='%s' value='%s' depth=%d", name, value, depth);
+    name_expand_size = 64 + strlen(name);
+    name_expand = (char *) malloc(name_expand_size);
+    check_malloc_return(name_expand);
+    openvpn_snprintf(name_expand, name_expand_size, "X509_%d_%s", depth, name);
+    setenv_str(es, name_expand, value);
+    free(name_expand);
+}
+
+static char *
+asn1_buf_to_c_string(const mbedtls_asn1_buf *orig, struct gc_arena *gc)
+{
+    size_t i;
+    char *val;
+
+    if (!(orig->tag == MBEDTLS_ASN1_UTF8_STRING
+          || orig->tag == MBEDTLS_ASN1_PRINTABLE_STRING
+          || orig->tag == MBEDTLS_ASN1_IA5_STRING))
+    {
+        /* Only support C-string compatible types */
+        return string_alloc("ERROR: unsupported ASN.1 string type", gc);
+    }
+
+    for (i = 0; i < orig->len; ++i)
+    {
+        if (orig->p[i] == '\0')
+        {
+            return string_alloc("ERROR: embedded null value", gc);
+        }
+    }
+    val = gc_malloc(orig->len+1, false, gc);
+    memcpy(val, orig->p, orig->len);
+    val[orig->len] = '\0';
+    return val;
+}
+
+static void
+do_setenv_name(struct env_set *es, const struct x509_track *xt,
+               const mbedtls_x509_crt *cert, int depth, struct gc_arena *gc)
+{
+    const mbedtls_x509_name *xn;
+    for (xn = &cert->subject; xn != NULL; xn = xn->next)
+    {
+        const char *xn_short_name = NULL;
+        if (0 == mbedtls_oid_get_attr_short_name(&xn->oid, &xn_short_name)
+            && 0 == strcmp(xt->name, xn_short_name))
+        {
+            char *val_str = asn1_buf_to_c_string(&xn->val, gc);
+            do_setenv_x509(es, xt->name, val_str, depth);
+        }
+    }
+}
+
+void
+x509_track_add(const struct x509_track **ll_head, const char *name, int msglevel, struct gc_arena *gc)
+{
+    struct x509_track *xt;
+    ALLOC_OBJ_CLEAR_GC(xt, struct x509_track, gc);
+    if (*name == '+')
+    {
+        xt->flags |= XT_FULL_CHAIN;
+        ++name;
+    }
+    xt->name = name;
+    xt->next = *ll_head;
+    *ll_head = xt;
+}
+
+void
+x509_setenv_track(const struct x509_track *xt, struct env_set *es,
+                  const int depth, mbedtls_x509_crt *cert)
+{
+    struct gc_arena gc = gc_new();
+    while (xt)
+    {
+        if (depth == 0 || (xt->flags & XT_FULL_CHAIN))
+        {
+            if (0 == strcmp(xt->name, "SHA1") || 0 == strcmp(xt->name, "SHA256"))
+            {
+                /* Fingerprint is not part of X509 structure */
+                struct buffer cert_hash;
+                char *fingerprint;
+
+                if (0 == strcmp(xt->name, "SHA1"))
+                {
+                    cert_hash = x509_get_sha1_fingerprint(cert, &gc);
+                }
+                else
+                {
+                    cert_hash = x509_get_sha256_fingerprint(cert, &gc);
+                }
+
+                fingerprint = format_hex_ex(BPTR(&cert_hash),
+                                            BLEN(&cert_hash), 0, 1 | FHE_CAPS, ":", &gc);
+                do_setenv_x509(es, xt->name, fingerprint, depth);
+            }
+            else
+            {
+                do_setenv_name(es, xt, cert, depth, &gc);
+            }
+        }
+        xt = xt->next;
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Save X509 fields to environment, using the naming convention:
+ *
+ * X509_{cert_depth}_{name}={value}
+ */
+void
+x509_setenv(struct env_set *es, int cert_depth, mbedtls_x509_crt *cert)
+{
+    int i;
+    unsigned char c;
+    const mbedtls_x509_name *name;
+    char s[128] = { 0 };
+
+    name = &cert->subject;
+
+    while (name != NULL)
+    {
+        char name_expand[64+8];
+        const char *shortname;
+
+        if (0 == mbedtls_oid_get_attr_short_name(&name->oid, &shortname) )
+        {
+            openvpn_snprintf(name_expand, sizeof(name_expand), "X509_%d_%s",
+                             cert_depth, shortname);
+        }
+        else
+        {
+            openvpn_snprintf(name_expand, sizeof(name_expand), "X509_%d_\?\?",
+                             cert_depth);
+        }
+
+        for (i = 0; i < name->val.len; i++)
+        {
+            if (i >= (int) sizeof( s ) - 1)
+            {
+                break;
+            }
+
+            c = name->val.p[i];
+            if (c < 32 || c == 127 || ( c > 128 && c < 160 ) )
+            {
+                s[i] = '?';
+            }
+            else
+            {
+                s[i] = c;
+            }
+        }
+        s[i] = '\0';
+
+        /* Check both strings, set environment variable */
+        string_mod(name_expand, CC_PRINT, CC_CRLF, '_');
+        string_mod((char *)s, CC_PRINT, CC_CRLF, '_');
+        setenv_str_incr(es, name_expand, (char *)s);
+
+        name = name->next;
+    }
+}
+
+result_t
+x509_verify_ns_cert_type(mbedtls_x509_crt *cert, const int usage)
+{
+    if (usage == NS_CERT_CHECK_NONE)
+    {
+        return SUCCESS;
+    }
+    if (usage == NS_CERT_CHECK_CLIENT)
+    {
+        return ((cert->ext_types & MBEDTLS_X509_EXT_NS_CERT_TYPE)
+                && (cert->ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_CLIENT)) ?
+               SUCCESS : FAILURE;
+    }
+    if (usage == NS_CERT_CHECK_SERVER)
+    {
+        return ((cert->ext_types & MBEDTLS_X509_EXT_NS_CERT_TYPE)
+                && (cert->ns_cert_type & MBEDTLS_X509_NS_CERT_TYPE_SSL_SERVER)) ?
+               SUCCESS : FAILURE;
+    }
+
+    return FAILURE;
+}
+
+result_t
+x509_verify_cert_ku(mbedtls_x509_crt *cert, const unsigned *const expected_ku,
+                    int expected_len)
+{
+    msg(D_HANDSHAKE, "Validating certificate key usage");
+
+    if (!(cert->ext_types & MBEDTLS_X509_EXT_KEY_USAGE))
+    {
+        msg(D_TLS_ERRORS,
+            "ERROR: Certificate does not have key usage extension");
+        return FAILURE;
+    }
+
+    if (expected_ku[0] == OPENVPN_KU_REQUIRED)
+    {
+        /* Extension required, value checked by TLS library */
+        return SUCCESS;
+    }
+
+    result_t fFound = FAILURE;
+    for (size_t i = 0; SUCCESS != fFound && i<expected_len; i++)
+    {
+        if (expected_ku[i] != 0
+            && 0 == mbedtls_x509_crt_check_key_usage(cert, expected_ku[i]))
+        {
+            fFound = SUCCESS;
+        }
+    }
+
+    if (fFound != SUCCESS)
+    {
+        msg(D_TLS_ERRORS,
+            "ERROR: Certificate has key usage %04x, expected one of:",
+            cert->key_usage);
+        for (size_t i = 0; i < expected_len && expected_ku[i]; i++)
+        {
+            msg(D_TLS_ERRORS, " * %04x", expected_ku[i]);
+        }
+    }
+
+    return fFound;
+}
+
+result_t
+x509_verify_cert_eku(mbedtls_x509_crt *cert, const char *const expected_oid)
+{
+    result_t fFound = FAILURE;
+
+    if (!(cert->ext_types & MBEDTLS_X509_EXT_EXTENDED_KEY_USAGE))
+    {
+        msg(D_HANDSHAKE, "Certificate does not have extended key usage extension");
+    }
+    else
+    {
+        mbedtls_x509_sequence *oid_seq = &(cert->ext_key_usage);
+
+        msg(D_HANDSHAKE, "Validating certificate extended key usage");
+        while (oid_seq != NULL)
+        {
+            mbedtls_x509_buf *oid = &oid_seq->buf;
+            char oid_num_str[1024];
+            const char *oid_str;
+
+            if (0 == mbedtls_oid_get_extended_key_usage( oid, &oid_str ))
+            {
+                msg(D_HANDSHAKE, "++ Certificate has EKU (str) %s, expects %s",
+                    oid_str, expected_oid);
+                if (!strcmp(expected_oid, oid_str))
+                {
+                    fFound = SUCCESS;
+                    break;
+                }
+            }
+
+            if (0 < mbedtls_oid_get_numeric_string( oid_num_str,
+                                                    sizeof(oid_num_str), oid))
+            {
+                msg(D_HANDSHAKE, "++ Certificate has EKU (oid) %s, expects %s",
+                    oid_num_str, expected_oid);
+                if (!strcmp(expected_oid, oid_num_str))
+                {
+                    fFound = SUCCESS;
+                    break;
+                }
+            }
+            oid_seq = oid_seq->next;
+        }
+    }
+
+    return fFound;
+}
+
+result_t
+x509_write_pem(FILE *peercert_file, mbedtls_x509_crt *peercert)
+{
+    msg(M_WARN, "mbed TLS does not support writing peer certificate in PEM format");
+    return FAILURE;
+}
+
+bool
+tls_verify_crl_missing(const struct tls_options *opt)
+{
+    if (opt->crl_file && !(opt->ssl_flags & SSLF_CRL_VERIFY_DIR)
+        && (opt->ssl_ctx.crl == NULL || opt->ssl_ctx.crl->version == 0))
+    {
+        return true;
+    }
+    return false;
+}
+
+#endif /* #if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS) */
diff --git a/src/openvpn/ssl_verify_mbedtls.h b/src/openvpn/ssl_verify_mbedtls.h
new file mode 100644
index 0000000..00dc8a3
--- /dev/null
+++ b/src/openvpn/ssl_verify_mbedtls.h
@@ -0,0 +1,77 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module mbed TLS backend
+ */
+
+#ifndef SSL_VERIFY_MBEDTLS_H_
+#define SSL_VERIFY_MBEDTLS_H_
+
+#include "syshead.h"
+#include <mbedtls/x509_crt.h>
+
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef mbedtls_x509_crt openvpn_x509_cert_t;
+#endif
+
+/** @name Function for authenticating a new connection from a remote OpenVPN peer
+ *  @{ */
+
+/**
+ * Verify that the remote OpenVPN peer's certificate allows setting up a
+ * VPN tunnel.
+ * @ingroup control_tls
+ *
+ * This callback function is called when a new TLS session is being setup to
+ * determine whether the remote OpenVPN peer's certificate is allowed to
+ * connect. It is called for once for every certificate in the chain. The
+ * callback functionality is configured in the \c key_state_ssl_init() function,
+ * which calls the mbed TLS library's \c mbedtls_ssl_conf_verify() function with
+ * \c verify_callback() as its callback argument.
+ *
+ * It checks *flags and registers the certificate hash. If these steps succeed,
+ * it calls the \c verify_cert() function, which performs OpenVPN-specific
+ * verification.
+ *
+ * @param session_obj  - The OpenVPN \c tls_session associated with this object,
+ *                       as set during SSL session setup.
+ * @param cert         - The certificate used by mbed TLS.
+ * @param cert_depth   - The depth of the current certificate in the chain, with
+ *                       0 being the actual certificate.
+ * @param flags        - Whether the remote OpenVPN peer's certificate
+ *                       passed verification.  A value of 0 means it
+ *                       verified successfully, any other value means it
+ *                       failed. \c verify_callback() is considered to have
+ *                       ok'ed this certificate if flags is 0 when it returns.
+ *
+ * @return The return value is 0 unless a fatal error occurred.
+ */
+int verify_callback(void *session_obj, mbedtls_x509_crt *cert, int cert_depth,
+                    uint32_t *flags);
+
+/** @} name Function for authenticating a new connection from a remote OpenVPN peer */
+
+#endif /* SSL_VERIFY_MBEDTLS_H_ */
diff --git a/src/openvpn/ssl_verify_openssl.c b/src/openvpn/ssl_verify_openssl.c
new file mode 100644
index 0000000..b1ce06b
--- /dev/null
+++ b/src/openvpn/ssl_verify_openssl.c
@@ -0,0 +1,805 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module OpenSSL implementation
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL)
+
+#include "ssl_verify_openssl.h"
+
+#include "error.h"
+#include "ssl_openssl.h"
+#include "ssl_verify.h"
+#include "ssl_verify_backend.h"
+#include "openssl_compat.h"
+
+#include <openssl/x509v3.h>
+#include <openssl/err.h>
+
+int
+verify_callback(int preverify_ok, X509_STORE_CTX *ctx)
+{
+    int ret = 0;
+    struct tls_session *session;
+    SSL *ssl;
+    struct gc_arena gc = gc_new();
+
+    /* get the tls_session pointer */
+    ssl = X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
+    ASSERT(ssl);
+    session = (struct tls_session *) SSL_get_ex_data(ssl, mydata_index);
+    ASSERT(session);
+
+    X509 *current_cert = X509_STORE_CTX_get_current_cert(ctx);
+    struct buffer cert_hash = x509_get_sha256_fingerprint(current_cert, &gc);
+    cert_hash_remember(session, X509_STORE_CTX_get_error_depth(ctx), &cert_hash);
+
+    /* did peer present cert which was signed by our root cert? */
+    if (!preverify_ok)
+    {
+        /* get the X509 name */
+        char *subject = x509_get_subject(current_cert, &gc);
+
+        if (!subject)
+        {
+            subject = "(Failed to retrieve certificate subject)";
+        }
+
+        /* Log and ignore missing CRL errors */
+        if (X509_STORE_CTX_get_error(ctx) == X509_V_ERR_UNABLE_TO_GET_CRL)
+        {
+            msg(D_TLS_DEBUG_LOW, "VERIFY WARNING: depth=%d, %s: %s",
+                X509_STORE_CTX_get_error_depth(ctx),
+                X509_verify_cert_error_string(X509_STORE_CTX_get_error(ctx)),
+                subject);
+            ret = 1;
+            goto cleanup;
+        }
+
+        /* Remote site specified a certificate, but it's not correct */
+        msg(D_TLS_ERRORS, "VERIFY ERROR: depth=%d, error=%s: %s",
+            X509_STORE_CTX_get_error_depth(ctx),
+            X509_verify_cert_error_string(X509_STORE_CTX_get_error(ctx)),
+            subject);
+
+        ERR_clear_error();
+
+        session->verified = false;
+        goto cleanup;
+    }
+
+    if (SUCCESS != verify_cert(session, current_cert, X509_STORE_CTX_get_error_depth(ctx)))
+    {
+        goto cleanup;
+    }
+
+    ret = 1;
+
+cleanup:
+    gc_free(&gc);
+
+    return ret;
+}
+
+#ifdef ENABLE_X509ALTUSERNAME
+bool x509_username_field_ext_supported(const char *fieldname)
+{
+    int nid = OBJ_txt2nid(fieldname);
+    return nid == NID_subject_alt_name || nid == NID_issuer_alt_name;
+}
+
+static
+bool
+extract_x509_extension(X509 *cert, char *fieldname, char *out, int size)
+{
+    bool retval = false;
+    char *buf = 0;
+
+    if (!x509_username_field_ext_supported(fieldname))
+    {
+        msg(D_TLS_ERRORS,
+            "ERROR: --x509-username-field 'ext:%s' not supported", fieldname);
+        return false;
+    }
+
+    int nid = OBJ_txt2nid(fieldname);
+    GENERAL_NAMES *extensions = X509_get_ext_d2i(cert, nid, NULL, NULL);
+    if (extensions)
+    {
+        int numalts;
+        int i;
+        /* get amount of alternatives,
+         * RFC2459 claims there MUST be at least
+         * one, but we don't depend on it...
+         */
+
+        numalts = sk_GENERAL_NAME_num(extensions);
+
+        /* loop through all alternatives */
+        for (i = 0; i<numalts; i++)
+        {
+            /* get a handle to alternative name number i */
+            const GENERAL_NAME *name = sk_GENERAL_NAME_value(extensions, i );
+
+            switch (name->type)
+            {
+                case GEN_EMAIL:
+                    if (ASN1_STRING_to_UTF8((unsigned char **)&buf, name->d.ia5) < 0)
+                    {
+                        continue;
+                    }
+                    if (strlen(buf) != name->d.ia5->length)
+                    {
+                        msg(D_TLS_ERRORS, "ASN1 ERROR: string contained terminating zero");
+                        OPENSSL_free(buf);
+                    }
+                    else
+                    {
+                        strncpynt(out, buf, size);
+                        OPENSSL_free(buf);
+                        retval = true;
+                    }
+                    break;
+
+                default:
+                    msg(D_TLS_DEBUG, "%s: ignoring general name field type %i",
+                        __func__, name->type);
+                    break;
+            }
+        }
+        GENERAL_NAMES_free(extensions);
+    }
+    return retval;
+}
+#endif /* ENABLE_X509ALTUSERNAME */
+
+/*
+ * Extract a field from an X509 subject name.
+ *
+ * Example:
+ *
+ * /C=US/ST=CO/L=Denver/O=ORG/CN=First-CN/CN=Test-CA/Email=jim@yonan.net
+ *
+ * The common name is 'Test-CA'
+ *
+ * Return true on success, false on error (insufficient buffer size in 'out'
+ * to contain result is grounds for error).
+ */
+static result_t
+extract_x509_field_ssl(X509_NAME *x509, const char *field_name, char *out,
+                       int size)
+{
+    int lastpos = -1;
+    int tmp = -1;
+    X509_NAME_ENTRY *x509ne = NULL;
+    ASN1_STRING *asn1 = NULL;
+    unsigned char *buf = NULL;
+    ASN1_OBJECT *field_name_obj = OBJ_txt2obj(field_name, 0);
+
+    if (field_name_obj == NULL)
+    {
+        msg(D_TLS_ERRORS, "Invalid X509 attribute name '%s'", field_name);
+        return FAILURE;
+    }
+
+    ASSERT(size > 0);
+    *out = '\0';
+    do
+    {
+        lastpos = tmp;
+        tmp = X509_NAME_get_index_by_OBJ(x509, field_name_obj, lastpos);
+    } while (tmp > -1);
+
+    ASN1_OBJECT_free(field_name_obj);
+
+    /* Nothing found */
+    if (lastpos == -1)
+    {
+        return FAILURE;
+    }
+
+    x509ne = X509_NAME_get_entry(x509, lastpos);
+    if (!x509ne)
+    {
+        return FAILURE;
+    }
+
+    asn1 = X509_NAME_ENTRY_get_data(x509ne);
+    if (!asn1)
+    {
+        return FAILURE;
+    }
+    if (ASN1_STRING_to_UTF8(&buf, asn1) < 0)
+    {
+        return FAILURE;
+    }
+
+    strncpynt(out, (char *)buf, size);
+
+    {
+        const result_t ret = (strlen((char *)buf) < size) ? SUCCESS : FAILURE;
+        OPENSSL_free(buf);
+        return ret;
+    }
+}
+
+result_t
+backend_x509_get_username(char *common_name, int cn_len,
+                          char *x509_username_field, X509 *peer_cert)
+{
+#ifdef ENABLE_X509ALTUSERNAME
+    if (strncmp("ext:",x509_username_field,4) == 0)
+    {
+        if (!extract_x509_extension(peer_cert, x509_username_field+4, common_name, cn_len))
+        {
+            return FAILURE;
+        }
+    }
+    else
+#endif
+    if (FAILURE == extract_x509_field_ssl(X509_get_subject_name(peer_cert),
+                                          x509_username_field, common_name, cn_len))
+    {
+        return FAILURE;
+    }
+
+    return SUCCESS;
+}
+
+char *
+backend_x509_get_serial(openvpn_x509_cert_t *cert, struct gc_arena *gc)
+{
+    ASN1_INTEGER *asn1_i;
+    BIGNUM *bignum;
+    char *openssl_serial, *serial;
+
+    asn1_i = X509_get_serialNumber(cert);
+    bignum = ASN1_INTEGER_to_BN(asn1_i, NULL);
+    openssl_serial = BN_bn2dec(bignum);
+
+    serial = string_alloc(openssl_serial, gc);
+
+    BN_free(bignum);
+    OPENSSL_free(openssl_serial);
+
+    return serial;
+}
+
+char *
+backend_x509_get_serial_hex(openvpn_x509_cert_t *cert, struct gc_arena *gc)
+{
+    const ASN1_INTEGER *asn1_i = X509_get_serialNumber(cert);
+
+    return format_hex_ex(asn1_i->data, asn1_i->length, 0, 1, ":", gc);
+}
+
+struct buffer
+x509_get_sha1_fingerprint(X509 *cert, struct gc_arena *gc)
+{
+    const EVP_MD *sha1 = EVP_sha1();
+    struct buffer hash = alloc_buf_gc(EVP_MD_size(sha1), gc);
+    X509_digest(cert, EVP_sha1(), BPTR(&hash), NULL);
+    ASSERT(buf_inc_len(&hash, EVP_MD_size(sha1)));
+    return hash;
+}
+
+struct buffer
+x509_get_sha256_fingerprint(X509 *cert, struct gc_arena *gc)
+{
+    const EVP_MD *sha256 = EVP_sha256();
+    struct buffer hash = alloc_buf_gc(EVP_MD_size(sha256), gc);
+    X509_digest(cert, EVP_sha256(), BPTR(&hash), NULL);
+    ASSERT(buf_inc_len(&hash, EVP_MD_size(sha256)));
+    return hash;
+}
+
+char *
+x509_get_subject(X509 *cert, struct gc_arena *gc)
+{
+    BIO *subject_bio = NULL;
+    BUF_MEM *subject_mem;
+    char *subject = NULL;
+
+    /*
+     * Generate the subject string in OpenSSL proprietary format,
+     * when in --compat-names mode
+     */
+    if (compat_flag(COMPAT_FLAG_QUERY | COMPAT_NAMES))
+    {
+        subject = gc_malloc(256, false, gc);
+        X509_NAME_oneline(X509_get_subject_name(cert), subject, 256);
+        subject[255] = '\0';
+        return subject;
+    }
+
+    subject_bio = BIO_new(BIO_s_mem());
+    if (subject_bio == NULL)
+    {
+        goto err;
+    }
+
+    X509_NAME_print_ex(subject_bio, X509_get_subject_name(cert),
+                       0, XN_FLAG_SEP_CPLUS_SPC | XN_FLAG_FN_SN
+                       |ASN1_STRFLGS_UTF8_CONVERT | ASN1_STRFLGS_ESC_CTRL);
+
+    if (BIO_eof(subject_bio))
+    {
+        goto err;
+    }
+
+    BIO_get_mem_ptr(subject_bio, &subject_mem);
+
+    subject = gc_malloc(subject_mem->length + 1, false, gc);
+
+    memcpy(subject, subject_mem->data, subject_mem->length);
+    subject[subject_mem->length] = '\0';
+
+err:
+    if (subject_bio)
+    {
+        BIO_free(subject_bio);
+    }
+
+    return subject;
+}
+
+
+/*
+ * x509-track implementation -- save X509 fields to environment,
+ * using the naming convention:
+ *
+ *  X509_{cert_depth}_{name}={value}
+ *
+ * This function differs from x509_setenv below in the following ways:
+ *
+ * (1) Only explicitly named attributes in xt are saved, per usage
+ *     of "x509-track" program options.
+ * (2) Only the level 0 cert info is saved unless the XT_FULL_CHAIN
+ *     flag is set in xt->flags (corresponds with prepending a '+'
+ *     to the name when specified by "x509-track" program option).
+ * (3) This function supports both X509 subject name fields as
+ *     well as X509 V3 extensions.
+ * (4) This function can return the SHA1 fingerprint of a cert, e.g.
+ *       x509-track "+SHA1"
+ *     will return the SHA1 fingerprint for each certificate in the
+ *     peer chain.
+ */
+
+void
+x509_track_add(const struct x509_track **ll_head, const char *name, int msglevel, struct gc_arena *gc)
+{
+    struct x509_track *xt;
+    ALLOC_OBJ_CLEAR_GC(xt, struct x509_track, gc);
+    if (*name == '+')
+    {
+        xt->flags |= XT_FULL_CHAIN;
+        ++name;
+    }
+    xt->name = name;
+    xt->nid = OBJ_txt2nid(name);
+    if (xt->nid != NID_undef)
+    {
+        xt->next = *ll_head;
+        *ll_head = xt;
+    }
+    else
+    {
+        msg(msglevel, "x509_track: no such attribute '%s'", name);
+    }
+}
+
+/* worker method for setenv_x509_track */
+static void
+do_setenv_x509(struct env_set *es, const char *name, char *value, int depth)
+{
+    char *name_expand;
+    size_t name_expand_size;
+
+    string_mod(value, CC_ANY, CC_CRLF, '?');
+    msg(D_X509_ATTR, "X509 ATTRIBUTE name='%s' value='%s' depth=%d", name, value, depth);
+    name_expand_size = 64 + strlen(name);
+    name_expand = (char *) malloc(name_expand_size);
+    check_malloc_return(name_expand);
+    openvpn_snprintf(name_expand, name_expand_size, "X509_%d_%s", depth, name);
+    setenv_str(es, name_expand, value);
+    free(name_expand);
+}
+
+void
+x509_setenv_track(const struct x509_track *xt, struct env_set *es, const int depth, X509 *x509)
+{
+    struct gc_arena gc = gc_new();
+    X509_NAME *x509_name = X509_get_subject_name(x509);
+    const char nullc = '\0';
+
+    while (xt)
+    {
+        if (depth == 0 || (xt->flags & XT_FULL_CHAIN))
+        {
+            switch (xt->nid)
+            {
+                case NID_sha1:
+                case NID_sha256:
+                {
+                    struct buffer fp_buf;
+                    char *fp_str = NULL;
+
+                    if (xt->nid == NID_sha1)
+                    {
+                        fp_buf = x509_get_sha1_fingerprint(x509, &gc);
+                    }
+                    else
+                    {
+                        fp_buf = x509_get_sha256_fingerprint(x509, &gc);
+                    }
+
+                    fp_str = format_hex_ex(BPTR(&fp_buf), BLEN(&fp_buf), 0,
+                                           1 | FHE_CAPS, ":", &gc);
+                    do_setenv_x509(es, xt->name, fp_str, depth);
+                }
+                break;
+
+                default:
+                {
+                    int i = X509_NAME_get_index_by_NID(x509_name, xt->nid, -1);
+                    if (i >= 0)
+                    {
+                        X509_NAME_ENTRY *ent = X509_NAME_get_entry(x509_name, i);
+                        if (ent)
+                        {
+                            ASN1_STRING *val = X509_NAME_ENTRY_get_data(ent);
+                            unsigned char *buf;
+                            buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */
+                            if (ASN1_STRING_to_UTF8(&buf, val) >= 0)
+                            {
+                                do_setenv_x509(es, xt->name, (char *)buf, depth);
+                                OPENSSL_free(buf);
+                            }
+                        }
+                    }
+                    else
+                    {
+                        i = X509_get_ext_by_NID(x509, xt->nid, -1);
+                        if (i >= 0)
+                        {
+                            X509_EXTENSION *ext = X509_get_ext(x509, i);
+                            if (ext)
+                            {
+                                BIO *bio = BIO_new(BIO_s_mem());
+                                if (bio)
+                                {
+                                    if (X509V3_EXT_print(bio, ext, 0, 0))
+                                    {
+                                        if (BIO_write(bio, &nullc, 1) == 1)
+                                        {
+                                            char *str;
+                                            BIO_get_mem_data(bio, &str);
+                                            do_setenv_x509(es, xt->name, str, depth);
+                                        }
+                                    }
+                                    BIO_free(bio);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        xt = xt->next;
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Save X509 fields to environment, using the naming convention:
+ *
+ *  X509_{cert_depth}_{name}={value}
+ */
+void
+x509_setenv(struct env_set *es, int cert_depth, openvpn_x509_cert_t *peer_cert)
+{
+    int i, n;
+    int fn_nid;
+    ASN1_OBJECT *fn;
+    ASN1_STRING *val;
+    X509_NAME_ENTRY *ent;
+    const char *objbuf;
+    unsigned char *buf;
+    char *name_expand;
+    size_t name_expand_size;
+    X509_NAME *x509 = X509_get_subject_name(peer_cert);
+
+    n = X509_NAME_entry_count(x509);
+    for (i = 0; i < n; ++i)
+    {
+        ent = X509_NAME_get_entry(x509, i);
+        if (!ent)
+        {
+            continue;
+        }
+        fn = X509_NAME_ENTRY_get_object(ent);
+        if (!fn)
+        {
+            continue;
+        }
+        val = X509_NAME_ENTRY_get_data(ent);
+        if (!val)
+        {
+            continue;
+        }
+        fn_nid = OBJ_obj2nid(fn);
+        if (fn_nid == NID_undef)
+        {
+            continue;
+        }
+        objbuf = OBJ_nid2sn(fn_nid);
+        if (!objbuf)
+        {
+            continue;
+        }
+        buf = (unsigned char *)1; /* bug in OpenSSL 0.9.6b ASN1_STRING_to_UTF8 requires this workaround */
+        if (ASN1_STRING_to_UTF8(&buf, val) < 0)
+        {
+            continue;
+        }
+        name_expand_size = 64 + strlen(objbuf);
+        name_expand = (char *) malloc(name_expand_size);
+        check_malloc_return(name_expand);
+        openvpn_snprintf(name_expand, name_expand_size, "X509_%d_%s", cert_depth,
+                         objbuf);
+        string_mod(name_expand, CC_PRINT, CC_CRLF, '_');
+        string_mod((char *)buf, CC_PRINT, CC_CRLF, '_');
+        setenv_str_incr(es, name_expand, (char *)buf);
+        free(name_expand);
+        OPENSSL_free(buf);
+    }
+}
+
+result_t
+x509_verify_ns_cert_type(openvpn_x509_cert_t *peer_cert, const int usage)
+{
+    if (usage == NS_CERT_CHECK_NONE)
+    {
+        return SUCCESS;
+    }
+    if (usage == NS_CERT_CHECK_CLIENT)
+    {
+        /*
+         * Unfortunately, X509_check_purpose() does some weird thing that
+         * prevent it to take a const argument
+         */
+        result_t result = X509_check_purpose(peer_cert, X509_PURPOSE_SSL_CLIENT, 0) ?
+	       SUCCESS : FAILURE;
+
+        /*
+         * old versions of OpenSSL allow us to make the less strict check we used to
+         * do. If this less strict check pass, warn user that this might not be the
+         * case when its distribution will update to OpenSSL 1.1
+         */
+        if (result == FAILURE)
+        {
+            ASN1_BIT_STRING *ns;
+            ns = X509_get_ext_d2i(peer_cert, NID_netscape_cert_type, NULL, NULL);
+            result = (ns && ns->length > 0 && (ns->data[0] & NS_SSL_CLIENT)) ? SUCCESS : FAILURE;
+            if (result == SUCCESS)
+            {
+                msg(M_WARN, "X509: Certificate is a client certificate yet it's purpose "
+                    "cannot be verified (check may fail in the future)");
+            }
+            ASN1_BIT_STRING_free(ns);
+        }
+        return result;
+    }
+    if (usage == NS_CERT_CHECK_SERVER)
+    {
+        /*
+         * Unfortunately, X509_check_purpose() does some weird thing that
+         * prevent it to take a const argument
+         */
+        result_t result = X509_check_purpose(peer_cert, X509_PURPOSE_SSL_SERVER, 0) ?
+	       SUCCESS : FAILURE;
+
+        /*
+         * old versions of OpenSSL allow us to make the less strict check we used to
+         * do. If this less strict check pass, warn user that this might not be the
+         * case when its distribution will update to OpenSSL 1.1
+         */
+        if (result == FAILURE)
+        {
+            ASN1_BIT_STRING *ns;
+            ns = X509_get_ext_d2i(peer_cert, NID_netscape_cert_type, NULL, NULL);
+            result = (ns && ns->length > 0 && (ns->data[0] & NS_SSL_SERVER)) ? SUCCESS : FAILURE;
+            if (result == SUCCESS)
+            {
+                msg(M_WARN, "X509: Certificate is a server certificate yet it's purpose "
+                    "cannot be verified (check may fail in the future)");
+            }
+            ASN1_BIT_STRING_free(ns);
+        }
+        return result;
+    }
+
+    return FAILURE;
+}
+
+result_t
+x509_verify_cert_ku(X509 *x509, const unsigned *const expected_ku,
+                    int expected_len)
+{
+    ASN1_BIT_STRING *ku = X509_get_ext_d2i(x509, NID_key_usage, NULL, NULL);
+
+    if (ku == NULL)
+    {
+        msg(D_TLS_ERRORS, "Certificate does not have key usage extension");
+        return FAILURE;
+    }
+
+    if (expected_ku[0] == OPENVPN_KU_REQUIRED)
+    {
+        /* Extension required, value checked by TLS library */
+        ASN1_BIT_STRING_free(ku);
+        return SUCCESS;
+    }
+
+    unsigned nku = 0;
+    for (size_t i = 0; i < 8; i++)
+    {
+        if (ASN1_BIT_STRING_get_bit(ku, i))
+        {
+            nku |= 1 << (7 - i);
+        }
+    }
+
+    /*
+     * Fixup if no LSB bits
+     */
+    if ((nku & 0xff) == 0)
+    {
+        nku >>= 8;
+    }
+
+    msg(D_HANDSHAKE, "Validating certificate key usage");
+    result_t fFound = FAILURE;
+    for (size_t i = 0; fFound != SUCCESS && i < expected_len; i++)
+    {
+        if (expected_ku[i] != 0 && (nku & expected_ku[i]) == expected_ku[i])
+        {
+            fFound = SUCCESS;
+        }
+    }
+
+    if (fFound != SUCCESS)
+    {
+        msg(D_TLS_ERRORS,
+            "ERROR: Certificate has key usage %04x, expected one of:", nku);
+        for (size_t i = 0; i < expected_len && expected_ku[i]; i++)
+        {
+            msg(D_TLS_ERRORS, " * %04x", expected_ku[i]);
+        }
+    }
+
+    ASN1_BIT_STRING_free(ku);
+
+    return fFound;
+}
+
+result_t
+x509_verify_cert_eku(X509 *x509, const char *const expected_oid)
+{
+    EXTENDED_KEY_USAGE *eku = NULL;
+    result_t fFound = FAILURE;
+
+    if ((eku = (EXTENDED_KEY_USAGE *) X509_get_ext_d2i(x509, NID_ext_key_usage,
+                                                       NULL, NULL)) == NULL)
+    {
+        msg(D_HANDSHAKE, "Certificate does not have extended key usage extension");
+    }
+    else
+    {
+        int i;
+
+        msg(D_HANDSHAKE, "Validating certificate extended key usage");
+        for (i = 0; SUCCESS != fFound && i < sk_ASN1_OBJECT_num(eku); i++)
+        {
+            ASN1_OBJECT *oid = sk_ASN1_OBJECT_value(eku, i);
+            char szOid[1024];
+
+            if (SUCCESS != fFound && OBJ_obj2txt(szOid, sizeof(szOid), oid, 0) != -1)
+            {
+                msg(D_HANDSHAKE, "++ Certificate has EKU (str) %s, expects %s",
+                    szOid, expected_oid);
+                if (!strcmp(expected_oid, szOid))
+                {
+                    fFound = SUCCESS;
+                }
+            }
+            if (SUCCESS != fFound && OBJ_obj2txt(szOid, sizeof(szOid), oid, 1) != -1)
+            {
+                msg(D_HANDSHAKE, "++ Certificate has EKU (oid) %s, expects %s",
+                    szOid, expected_oid);
+                if (!strcmp(expected_oid, szOid))
+                {
+                    fFound = SUCCESS;
+                }
+            }
+        }
+    }
+
+    if (eku != NULL)
+    {
+        sk_ASN1_OBJECT_pop_free(eku, ASN1_OBJECT_free);
+    }
+
+    return fFound;
+}
+
+result_t
+x509_write_pem(FILE *peercert_file, X509 *peercert)
+{
+    if (PEM_write_X509(peercert_file, peercert) < 0)
+    {
+        msg(M_ERR, "Failed to write peer certificate in PEM format");
+        return FAILURE;
+    }
+    return SUCCESS;
+}
+
+bool
+tls_verify_crl_missing(const struct tls_options *opt)
+{
+    if (!opt->crl_file || (opt->ssl_flags & SSLF_CRL_VERIFY_DIR))
+    {
+        return false;
+    }
+
+    X509_STORE *store = SSL_CTX_get_cert_store(opt->ssl_ctx.ctx);
+    if (!store)
+    {
+        crypto_msg(M_FATAL, "Cannot get certificate store");
+    }
+
+    STACK_OF(X509_OBJECT) *objs = X509_STORE_get0_objects(store);
+    for (int i = 0; i < sk_X509_OBJECT_num(objs); i++)
+    {
+        X509_OBJECT *obj = sk_X509_OBJECT_value(objs, i);
+        ASSERT(obj);
+        if (X509_OBJECT_get_type(obj) == X509_LU_CRL)
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+#endif /* defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL) */
diff --git a/src/openvpn/ssl_verify_openssl.h b/src/openvpn/ssl_verify_openssl.h
new file mode 100644
index 0000000..118e16f
--- /dev/null
+++ b/src/openvpn/ssl_verify_openssl.h
@@ -0,0 +1,75 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file Control Channel Verification Module OpenSSL backend
+ */
+
+
+#ifndef SSL_VERIFY_OPENSSL_H_
+#define SSL_VERIFY_OPENSSL_H_
+
+#include <openssl/x509.h>
+
+#ifndef __OPENVPN_X509_CERT_T_DECLARED
+#define __OPENVPN_X509_CERT_T_DECLARED
+typedef X509 openvpn_x509_cert_t;
+#endif
+
+/** @name Function for authenticating a new connection from a remote OpenVPN peer
+ *  @{ */
+
+/**
+ * Verify that the remote OpenVPN peer's certificate allows setting up a
+ * VPN tunnel.
+ * @ingroup control_tls
+ *
+ * This callback function is called every time a new TLS session is being
+ * setup to determine whether the remote OpenVPN peer's certificate is
+ * allowed to connect. It is called for once for every certificate in the chain.
+ * The callback functionality is configured in the \c init_ssl() function, which
+ * calls the OpenSSL library's \c SSL_CTX_set_verify() function with \c
+ * verify_callback() as its callback argument.
+ *
+ * It checks preverify_ok, and registers the certificate hash. If these steps
+ * succeed, it calls the \c verify_cert() function, which performs
+ * OpenVPN-specific verification.
+ *
+ * @param preverify_ok - Whether the remote OpenVPN peer's certificate
+ *                       past verification.  A value of 1 means it
+ *                       verified successfully, 0 means it failed.
+ * @param ctx          - The complete context used by the OpenSSL library
+ *                       to verify the certificate chain.
+ *
+ * @return The return value indicates whether the supplied certificate is
+ *     allowed to set up a VPN tunnel.  The following values can be
+ *     returned:
+ *      - \c 0: failure, this certificate is not allowed to connect.
+ *      - \c 1: success, this certificate is allowed to connect.
+ */
+int verify_callback(int preverify_ok, X509_STORE_CTX *ctx);
+
+/** @} name Function for authenticating a new connection from a remote OpenVPN peer */
+
+#endif /* SSL_VERIFY_OPENSSL_H_ */
diff --git a/src/openvpn/status.c b/src/openvpn/status.c
new file mode 100644
index 0000000..91391d1
--- /dev/null
+++ b/src/openvpn/status.c
@@ -0,0 +1,332 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "status.h"
+#include "perf.h"
+#include "misc.h"
+#include "fdmisc.h"
+
+#include "memdbg.h"
+
+/*
+ * printf-style interface for outputting status info
+ */
+
+static const char *
+print_status_mode(unsigned int flags)
+{
+    switch (flags)
+    {
+        case STATUS_OUTPUT_WRITE:
+            return "WRITE";
+
+        case STATUS_OUTPUT_READ:
+            return "READ";
+
+        case STATUS_OUTPUT_READ|STATUS_OUTPUT_WRITE:
+            return "READ/WRITE";
+
+        default:
+            return "UNDEF";
+    }
+}
+
+struct status_output *
+status_open(const char *filename,
+            const int refresh_freq,
+            const int msglevel,
+            const struct virtual_output *vout,
+            const unsigned int flags)
+{
+    struct status_output *so = NULL;
+    if (filename || msglevel >= 0 || vout)
+    {
+        ALLOC_OBJ_CLEAR(so, struct status_output);
+        so->flags = flags;
+        so->msglevel = msglevel;
+        so->vout = vout;
+        so->fd = -1;
+        buf_reset(&so->read_buf);
+        event_timeout_clear(&so->et);
+        if (filename)
+        {
+            switch (so->flags)
+            {
+                case STATUS_OUTPUT_WRITE:
+                    so->fd = platform_open(filename,
+                                           O_CREAT | O_TRUNC | O_WRONLY,
+                                           S_IRUSR | S_IWUSR);
+                    break;
+
+                case STATUS_OUTPUT_READ:
+                    so->fd = platform_open(filename,
+                                           O_RDONLY,
+                                           S_IRUSR | S_IWUSR);
+                    break;
+
+                case STATUS_OUTPUT_READ|STATUS_OUTPUT_WRITE:
+                    so->fd = platform_open(filename,
+                                           O_CREAT | O_RDWR,
+                                           S_IRUSR | S_IWUSR);
+                    break;
+
+                default:
+                    ASSERT(0);
+            }
+            if (so->fd >= 0)
+            {
+                so->filename = string_alloc(filename, NULL);
+                set_cloexec(so->fd);
+
+                /* allocate read buffer */
+                if (so->flags & STATUS_OUTPUT_READ)
+                {
+                    so->read_buf = alloc_buf(512);
+                }
+            }
+            else
+            {
+                msg(M_WARN, "Note: cannot open %s for %s", filename, print_status_mode(so->flags));
+                so->errors = true;
+            }
+        }
+        else
+        {
+            so->flags = STATUS_OUTPUT_WRITE;
+        }
+
+        if ((so->flags & STATUS_OUTPUT_WRITE) && refresh_freq > 0)
+        {
+            event_timeout_init(&so->et, refresh_freq, 0);
+        }
+    }
+    return so;
+}
+
+bool
+status_trigger(struct status_output *so)
+{
+    if (so)
+    {
+        struct timeval null;
+        CLEAR(null);
+        return event_timeout_trigger(&so->et, &null, ETT_DEFAULT);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+status_trigger_tv(struct status_output *so, struct timeval *tv)
+{
+    if (so)
+    {
+        return event_timeout_trigger(&so->et, tv, ETT_DEFAULT);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+void
+status_reset(struct status_output *so)
+{
+    if (so && so->fd >= 0)
+    {
+        lseek(so->fd, (off_t)0, SEEK_SET);
+    }
+}
+
+void
+status_flush(struct status_output *so)
+{
+    if (so && so->fd >= 0 && (so->flags & STATUS_OUTPUT_WRITE))
+    {
+#if defined(HAVE_FTRUNCATE)
+        {
+            const off_t off = lseek(so->fd, (off_t)0, SEEK_CUR);
+            if (ftruncate(so->fd, off) != 0)
+            {
+                msg(M_WARN | M_ERRNO, "Failed to truncate status file");
+            }
+        }
+#elif defined(HAVE_CHSIZE)
+        {
+            const long off = (long) lseek(so->fd, (off_t)0, SEEK_CUR);
+            chsize(so->fd, off);
+        }
+#else  /* if defined(HAVE_FTRUNCATE) */
+#warning both ftruncate and chsize functions appear to be missing from this OS
+#endif
+
+        /* clear read buffer */
+        if (buf_defined(&so->read_buf))
+        {
+            ASSERT(buf_init(&so->read_buf, 0));
+        }
+    }
+}
+
+/* return false if error occurred */
+bool
+status_close(struct status_output *so)
+{
+    bool ret = true;
+    if (so)
+    {
+        if (so->errors)
+        {
+            ret = false;
+        }
+        if (so->fd >= 0)
+        {
+            if (close(so->fd) < 0)
+            {
+                ret = false;
+            }
+        }
+        if (so->filename)
+        {
+            free(so->filename);
+        }
+        if (buf_defined(&so->read_buf))
+        {
+            free_buf(&so->read_buf);
+        }
+        free(so);
+    }
+    else
+    {
+        ret = false;
+    }
+    return ret;
+}
+
+#define STATUS_PRINTF_MAXLEN 512
+
+void
+status_printf(struct status_output *so, const char *format, ...)
+{
+    if (so && (so->flags & STATUS_OUTPUT_WRITE))
+    {
+        char buf[STATUS_PRINTF_MAXLEN+2]; /* leave extra bytes for CR, LF */
+        va_list arglist;
+        int stat;
+
+        va_start(arglist, format);
+        stat = vsnprintf(buf, STATUS_PRINTF_MAXLEN, format, arglist);
+        va_end(arglist);
+        buf[STATUS_PRINTF_MAXLEN - 1] = 0;
+
+        if (stat < 0 || stat >= STATUS_PRINTF_MAXLEN)
+        {
+            so->errors = true;
+        }
+
+        if (so->msglevel >= 0 && !so->errors)
+        {
+            msg(so->msglevel, "%s", buf);
+        }
+
+        if (so->fd >= 0 && !so->errors)
+        {
+            int len;
+            strcat(buf, "\n");
+            len = strlen(buf);
+            if (len > 0)
+            {
+                if (write(so->fd, buf, len) != len)
+                {
+                    so->errors = true;
+                }
+            }
+        }
+
+        if (so->vout && !so->errors)
+        {
+            chomp(buf);
+            (*so->vout->func)(so->vout->arg, so->vout->flags_default, buf);
+        }
+    }
+}
+
+bool
+status_read(struct status_output *so, struct buffer *buf)
+{
+    bool ret = false;
+
+    if (so && so->fd >= 0 && (so->flags & STATUS_OUTPUT_READ))
+    {
+        ASSERT(buf_defined(&so->read_buf));
+        ASSERT(buf_defined(buf));
+        while (true)
+        {
+            const int c = buf_read_u8(&so->read_buf);
+
+            /* read more of file into buffer */
+            if (c == -1)
+            {
+                int len;
+
+                ASSERT(buf_init(&so->read_buf, 0));
+                len = read(so->fd, BPTR(&so->read_buf), BCAP(&so->read_buf));
+                if (len <= 0)
+                {
+                    break;
+                }
+
+                ASSERT(buf_inc_len(&so->read_buf, len));
+                continue;
+            }
+
+            ret = true;
+
+            if (c == '\r')
+            {
+                continue;
+            }
+
+            if (c == '\n')
+            {
+                break;
+            }
+
+            buf_write_u8(buf, c);
+        }
+
+        buf_null_terminate(buf);
+    }
+
+    return ret;
+}
diff --git a/src/openvpn/status.h b/src/openvpn/status.h
new file mode 100644
index 0000000..2a399d7
--- /dev/null
+++ b/src/openvpn/status.h
@@ -0,0 +1,107 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef STATUS_H
+#define STATUS_H
+
+#include "interval.h"
+
+/*
+ * virtual function interface for status output
+ */
+struct virtual_output {
+    void *arg;
+    unsigned int flags_default;
+    void (*func) (void *arg, const unsigned int flags, const char *str);
+};
+
+static inline void
+virtual_output_print(const struct virtual_output *vo, const unsigned int flags, const char *str)
+{
+    (*vo->func)(vo->arg, flags, str);
+}
+
+/*
+ * printf-style interface for inputting/outputting status info
+ */
+
+struct status_output
+{
+#define STATUS_OUTPUT_READ  (1<<0)
+#define STATUS_OUTPUT_WRITE (1<<1)
+    unsigned int flags;
+
+    char *filename;
+    int fd;
+    int msglevel;
+    const struct virtual_output *vout;
+
+    struct buffer read_buf;
+
+    struct event_timeout et;
+
+    bool errors;
+};
+
+struct status_output *status_open(const char *filename,
+                                  const int refresh_freq,
+                                  const int msglevel,
+                                  const struct virtual_output *vout,
+                                  const unsigned int flags);
+
+bool status_trigger_tv(struct status_output *so, struct timeval *tv);
+
+bool status_trigger(struct status_output *so);
+
+void status_reset(struct status_output *so);
+
+void status_flush(struct status_output *so);
+
+bool status_close(struct status_output *so);
+
+void status_printf(struct status_output *so, const char *format, ...)
+#ifdef __GNUC__
+#if __USE_MINGW_ANSI_STDIO
+__attribute__ ((format(gnu_printf, 2, 3)))
+#else
+__attribute__ ((format(__printf__, 2, 3)))
+#endif
+#endif
+;
+
+bool status_read(struct status_output *so, struct buffer *buf);
+
+static inline unsigned int
+status_rw_flags(const struct status_output *so)
+{
+    if (so)
+    {
+        return so->flags;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+#endif /* ifndef STATUS_H */
diff --git a/src/openvpn/syshead.h b/src/openvpn/syshead.h
new file mode 100644
index 0000000..3ac9d70
--- /dev/null
+++ b/src/openvpn/syshead.h
@@ -0,0 +1,706 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef SYSHEAD_H
+#define SYSHEAD_H
+
+#include "compat.h"
+#include <stdbool.h>
+
+/* branch prediction hints */
+#if defined(__GNUC__)
+#define likely(x)       __builtin_expect((x),1)
+#define unlikely(x)     __builtin_expect((x),0)
+#else
+#define likely(x)      (x)
+#define unlikely(x)    (x)
+#endif
+
+#ifdef _WIN32
+#include <windows.h>
+#include <winsock2.h>
+#define sleep(x) Sleep((x)*1000)
+#define random rand
+#define srandom srand
+#endif
+
+#ifdef _MSC_VER /* Visual Studio */
+#define __func__ __FUNCTION__
+#define __attribute__(x)
+#endif
+
+#if defined(__APPLE__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1070
+#define __APPLE_USE_RFC_3542  1
+#endif
+#endif
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+
+#ifdef HAVE_SYS_WAIT_H
+#include <sys/wait.h>
+#endif
+
+#ifndef _WIN32
+#ifndef WEXITSTATUS
+#define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
+#endif
+#ifndef WIFEXITED
+#define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
+#endif
+#endif
+
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#ifdef HAVE_TIME_H
+#include <time.h>
+#endif
+
+#ifdef HAVE_SYS_SOCKET_H
+#include <sys/socket.h>
+#endif
+
+#ifdef HAVE_SYS_UN_H
+#include <sys/un.h>
+#endif
+
+#ifdef HAVE_SYS_IOCTL_H
+#include <sys/ioctl.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
+#ifdef HAVE_DIRECT_H
+#include <direct.h>
+#endif
+
+#ifdef HAVE_IO_H
+#include <io.h>
+#endif
+
+#ifdef HAVE_SYS_FILE_H
+#include <sys/file.h>
+#endif
+
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+
+#ifdef HAVE_INTTYPES_H
+#include <inttypes.h>
+#elif defined(HAVE_STDINT_H)
+#include <stdint.h>
+#endif
+
+#ifdef HAVE_STDARG_H
+#include <stdarg.h>
+#endif
+
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef HAVE_SIGNAL_H
+#include <signal.h>
+#endif
+
+#ifdef HAVE_LIMITS_H
+#include <limits.h>
+#endif
+
+#ifdef HAVE_STDIO_H
+#include <stdio.h>
+#endif
+
+#ifdef HAVE_CTYPE_H
+#include <ctype.h>
+#endif
+
+#ifdef HAVE_ERRNO_H
+#include <errno.h>
+#endif
+
+#ifdef HAVE_ERR_H
+#include <err.h>
+#endif
+
+#ifdef HAVE_SYSLOG_H
+#include <syslog.h>
+#endif
+
+#ifdef HAVE_PWD_H
+#include <pwd.h>
+#endif
+
+#ifdef HAVE_GRP_H
+#include <grp.h>
+#endif
+
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+
+#ifdef HAVE_RESOLV_H
+#include <resolv.h>
+#endif
+
+#ifdef HAVE_SYS_POLL_H
+#include <sys/poll.h>
+#endif
+
+#ifdef HAVE_SYS_EPOLL_H
+#include <sys/epoll.h>
+#endif
+
+#ifdef ENABLE_SELINUX
+#include <selinux/selinux.h>
+#endif
+
+#if defined(HAVE_LIBGEN_H)
+#include <libgen.h>
+#endif
+
+#ifdef TARGET_SOLARIS
+#ifdef HAVE_STRINGS_H
+#include <strings.h>
+#endif
+#else
+#ifdef HAVE_STRING_H
+#include <string.h>
+#endif
+#endif
+
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+
+#ifdef HAVE_NET_IF_H
+#include <net/if.h>
+#endif
+
+#ifdef TARGET_NETBSD
+#include <net/if_tap.h>
+#endif
+
+#if defined(TARGET_LINUX) || defined (TARGET_ANDROID)
+
+#ifdef HAVE_LINUX_IF_TUN_H
+#include <linux/if_tun.h>
+#endif
+
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+
+#ifdef HAVE_LINUX_SOCKIOS_H
+#include <linux/sockios.h>
+#endif
+
+#ifdef HAVE_LINUX_TYPES_H
+#include <linux/types.h>
+#endif
+
+#ifdef HAVE_LINUX_ERRQUEUE_H
+#include <linux/errqueue.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#endif /* TARGET_LINUX */
+
+#ifdef TARGET_SOLARIS
+
+#ifdef HAVE_STROPTS_H
+#include <stropts.h>
+#undef S_ERROR
+#endif
+
+#ifdef HAVE_NET_IF_TUN_H
+#include <net/if_tun.h>
+#endif
+
+#ifdef HAVE_SYS_SOCKIO_H
+#include <sys/sockio.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_SYSTM_H
+#include <netinet/in_systm.h>
+#endif
+
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#endif /* TARGET_SOLARIS */
+
+#ifdef TARGET_OPENBSD
+
+#ifdef HAVE_SYS_UIO_H
+#include <sys/uio.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_SYSTM_H
+#include <netinet/in_systm.h>
+#endif
+
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#ifdef HAVE_NET_IF_TUN_H
+#include <net/if_tun.h>
+#endif
+
+#endif /* TARGET_OPENBSD */
+
+#ifdef TARGET_FREEBSD
+
+#ifdef HAVE_SYS_UIO_H
+#include <sys/uio.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_SYSTM_H
+#include <netinet/in_systm.h>
+#endif
+
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#ifdef HAVE_NET_IF_TUN_H
+#include <net/if_tun.h>
+#endif
+
+#endif /* TARGET_FREEBSD */
+
+#ifdef TARGET_NETBSD
+
+#ifdef HAVE_NET_IF_TUN_H
+#include <net/if_tun.h>
+#endif
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#endif /* TARGET_NETBSD */
+
+#ifdef TARGET_DRAGONFLY
+
+#ifdef HAVE_SYS_UIO_H
+#include <sys/uio.h>
+#endif
+
+#ifdef HAVE_NETINET_IN_SYSTM_H
+#include <netinet/in_systm.h>
+#endif
+
+#ifdef HAVE_NETINET_IP_H
+#include <netinet/ip.h>
+#endif
+
+#ifdef HAVE_NET_TUN_IF_TUN_H
+#include <net/tun/if_tun.h>
+#endif
+
+#endif /* TARGET_DRAGONFLY */
+
+#ifdef TARGET_DARWIN
+
+#ifdef HAVE_NETINET_TCP_H
+#include <netinet/tcp.h>
+#endif
+
+#endif /* TARGET_DARWIN */
+
+#ifdef _WIN32
+/* Missing declarations for MinGW 32. */
+/* #if !defined(__MINGW64_VERSION_MAJOR) || __MINGW64_VERSION_MAJOR < 2 */
+typedef int MIB_TCP_STATE;
+/* #endif */
+#include <naptypes.h>
+#include <ntddndis.h>
+#include <iphlpapi.h>
+#include <wininet.h>
+#include <shellapi.h>
+/* The following two headers are needed of PF_INET6 */
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#endif
+
+#ifdef HAVE_SYS_MMAN_H
+#ifdef TARGET_DARWIN
+#define _P1003_1B_VISIBLE
+#endif /* TARGET_DARWIN */
+#include <sys/mman.h>
+#endif
+
+/*
+ * Pedantic mode is meant to accomplish lint-style program checking,
+ * not to build a working executable.
+ */
+#ifdef PEDANTIC
+#undef HAVE_CPP_VARARG_MACRO_GCC
+#undef HAVE_CPP_VARARG_MACRO_ISO
+#undef EMPTY_ARRAY_SIZE
+#define EMPTY_ARRAY_SIZE 1
+#undef inline
+#define inline
+#endif
+
+/*
+ * Do we have the capability to support the --passtos option?
+ */
+#if defined(IPPROTO_IP) && defined(IP_TOS) && defined(HAVE_SETSOCKOPT)
+#define PASSTOS_CAPABILITY 1
+#else
+#define PASSTOS_CAPABILITY 0
+#endif
+
+/*
+ * Do we have nanoseconds gettimeofday?
+ */
+#if defined(HAVE_GETTIMEOFDAY) || defined(_WIN32)
+#define HAVE_GETTIMEOFDAY_NANOSECONDS 1
+#endif
+
+/*
+ * Do we have the capability to report extended socket errors?
+ */
+#if defined(HAVE_LINUX_TYPES_H) && defined(HAVE_LINUX_ERRQUEUE_H) && defined(HAVE_SOCK_EXTENDED_ERR) && defined(HAVE_MSGHDR) && defined(HAVE_CMSGHDR) && defined(CMSG_FIRSTHDR) && defined(CMSG_NXTHDR) && defined(IP_RECVERR) && defined(MSG_ERRQUEUE) && defined(SOL_IP) && defined(HAVE_IOVEC)
+#define EXTENDED_SOCKET_ERROR_CAPABILITY 1
+#else
+#define EXTENDED_SOCKET_ERROR_CAPABILITY 0
+#endif
+
+/*
+ * Does this platform support linux-style IP_PKTINFO
+ * or bsd-style IP_RECVDSTADDR ?
+ */
+#if defined(ENABLE_MULTIHOME) && ((defined(HAVE_IN_PKTINFO) && defined(IP_PKTINFO)) || defined(IP_RECVDSTADDR)) && defined(HAVE_MSGHDR) && defined(HAVE_CMSGHDR) && defined(HAVE_IOVEC) && defined(CMSG_FIRSTHDR) && defined(CMSG_NXTHDR) && defined(HAVE_RECVMSG) && defined(HAVE_SENDMSG)
+#define ENABLE_IP_PKTINFO 1
+#else
+#define ENABLE_IP_PKTINFO 0
+#endif
+
+/*
+ * Does this platform define SOL_IP
+ * or only bsd-style IPPROTO_IP ?
+ */
+#ifndef SOL_IP
+#define SOL_IP IPPROTO_IP
+#endif
+
+/*
+ * Define type sa_family_t if it isn't defined in the socket headers
+ */
+#ifndef HAVE_SA_FAMILY_T
+typedef unsigned short sa_family_t;
+#endif
+
+/*
+ * Disable ESEC
+ */
+#if 0
+#undef EXTENDED_SOCKET_ERROR_CAPABILITY
+#define EXTENDED_SOCKET_ERROR_CAPABILITY 0
+#endif
+
+/*
+ * Do we have a syslog capability?
+ */
+#if defined(HAVE_OPENLOG) && defined(HAVE_SYSLOG)
+#define SYSLOG_CAPABILITY 1
+#else
+#define SYSLOG_CAPABILITY 0
+#endif
+
+/*
+ * Does this OS draw a distinction between binary and ascii files?
+ */
+#ifndef O_BINARY
+#define O_BINARY 0
+#endif
+
+/*
+ * Directory separation char
+ */
+#ifdef _WIN32
+#define OS_SPECIFIC_DIRSEP '\\'
+#else
+#define OS_SPECIFIC_DIRSEP '/'
+#endif
+
+/*
+ * Our socket descriptor type.
+ */
+#ifdef _WIN32
+#define SOCKET_UNDEFINED (INVALID_SOCKET)
+typedef SOCKET socket_descriptor_t;
+#else
+#define SOCKET_UNDEFINED (-1)
+typedef int socket_descriptor_t;
+#endif
+
+static inline int
+socket_defined(const socket_descriptor_t sd)
+{
+    return sd != SOCKET_UNDEFINED;
+}
+
+/*
+ * Should statistics counters be 64 bits?
+ */
+#define USE_64_BIT_COUNTERS
+
+/*
+ * Should we enable the use of execve() for calling subprocesses,
+ * instead of system()?
+ */
+#if defined(HAVE_EXECVE) && defined(HAVE_FORK)
+#define ENABLE_FEATURE_EXECVE
+#endif
+
+/*
+ * Do we have point-to-multipoint capability?
+ */
+
+#if defined(ENABLE_CRYPTO) && defined(HAVE_GETTIMEOFDAY_NANOSECONDS)
+#define P2MP 1
+#else
+#define P2MP 0
+#endif
+
+#if P2MP && !defined(ENABLE_CLIENT_ONLY)
+#define P2MP_SERVER 1
+#else
+#define P2MP_SERVER 0
+#endif
+
+/*
+ * HTTPS port sharing capability
+ */
+#if defined(ENABLE_PORT_SHARE) && P2MP_SERVER && defined(SCM_RIGHTS) && defined(HAVE_MSGHDR) && defined(HAVE_CMSGHDR) && defined(HAVE_IOVEC) && defined(CMSG_FIRSTHDR) && defined(CMSG_NXTHDR) && defined(HAVE_RECVMSG) && defined(HAVE_SENDMSG)
+#define PORT_SHARE 1
+#else
+#define PORT_SHARE 0
+#endif
+
+/*
+ * Enable deferred authentication?
+ */
+#if defined(ENABLE_DEF_AUTH) && P2MP_SERVER && defined(ENABLE_PLUGIN)
+#define PLUGIN_DEF_AUTH
+#endif
+#if defined(ENABLE_DEF_AUTH) && P2MP_SERVER && defined(ENABLE_MANAGEMENT)
+#define MANAGEMENT_DEF_AUTH
+#endif
+#if !defined(PLUGIN_DEF_AUTH) && !defined(MANAGEMENT_DEF_AUTH)
+#undef ENABLE_DEF_AUTH
+#endif
+
+/*
+ * Enable external private key
+ */
+#if defined(ENABLE_MANAGEMENT) && defined(ENABLE_CRYPTO)
+#define MANAGMENT_EXTERNAL_KEY
+#endif
+
+/* Enable mbed TLS RNG prediction resistance support */
+#ifdef ENABLE_CRYPTO_MBEDTLS
+#define ENABLE_PREDICTION_RESISTANCE
+#endif /* ENABLE_CRYPTO_MBEDTLS */
+
+/*
+ * MANAGEMENT_IN_EXTRA allows the management interface to
+ * read multi-line inputs from clients.
+ */
+#if defined(MANAGEMENT_DEF_AUTH) || defined(MANAGMENT_EXTERNAL_KEY)
+#define MANAGEMENT_IN_EXTRA
+#endif
+
+/*
+ * Enable packet filter?
+ */
+#if defined(ENABLE_PF) && P2MP_SERVER && defined(ENABLE_PLUGIN) && defined(HAVE_STAT)
+#define PLUGIN_PF
+#endif
+#if defined(ENABLE_PF) && P2MP_SERVER && defined(MANAGEMENT_DEF_AUTH)
+#define MANAGEMENT_PF
+#endif
+#if !defined(PLUGIN_PF) && !defined(MANAGEMENT_PF)
+#undef ENABLE_PF
+#endif
+
+/*
+ * Do we support Unix domain sockets?
+ */
+#if defined(PF_UNIX) && !defined(_WIN32)
+#define UNIX_SOCK_SUPPORT 1
+#else
+#define UNIX_SOCK_SUPPORT 0
+#endif
+
+/*
+ * Should we include OCC (options consistency check) code?
+ */
+#define ENABLE_OCC
+
+/*
+ * Should we include NTLM proxy functionality
+ */
+#if defined(ENABLE_CRYPTO)
+#define NTLM 1
+#else
+#define NTLM 0
+#endif
+
+/*
+ * Should we include proxy digest auth functionality
+ */
+#if defined(ENABLE_CRYPTO)
+#define PROXY_DIGEST_AUTH 1
+#else
+#define PROXY_DIGEST_AUTH 0
+#endif
+
+/*
+ * Do we have CryptoAPI capability?
+ */
+#if defined(_WIN32) && defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_OPENSSL)
+#define ENABLE_CRYPTOAPI
+#endif
+
+/*
+ * Is poll available on this platform?
+ */
+#if defined(HAVE_POLL) && defined(HAVE_SYS_POLL_H)
+#define POLL 1
+#else
+#define POLL 0
+#endif
+
+/*
+ * Is epoll available on this platform?
+ */
+#if defined(HAVE_EPOLL_CREATE) && defined(HAVE_SYS_EPOLL_H)
+#define EPOLL 1
+#else
+#define EPOLL 0
+#endif
+
+/* Disable EPOLL */
+#if 0
+#undef EPOLL
+#define EPOLL 0
+#endif
+
+/*
+ * Reduce sensitivity to system clock instability
+ * and backtracks.
+ */
+#if defined(HAVE_GETTIMEOFDAY_NANOSECONDS)
+#define TIME_BACKTRACK_PROTECTION 1
+#endif
+
+/*
+ * Enable traffic shaper.
+ */
+#if defined(HAVE_GETTIMEOFDAY_NANOSECONDS)
+#define ENABLE_FEATURE_SHAPER 1
+#endif
+
+/*
+ * Is non-blocking connect() supported?
+ */
+#if defined(HAVE_GETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_ERROR) && defined(EINPROGRESS) && defined(ETIMEDOUT)
+#define CONNECT_NONBLOCK
+#endif
+
+/*
+ * Do we have the capability to support the AUTO_USERID feature?
+ */
+#if defined(ENABLE_AUTO_USERID)
+#define AUTO_USERID 1
+#else
+#define AUTO_USERID 0
+#endif
+
+/*
+ * Do we support challenge/response authentication as client?
+ */
+#if defined(ENABLE_MANAGEMENT)
+#define ENABLE_CLIENT_CR
+#endif
+
+/*
+ * Do we support pushing peer info?
+ */
+#if defined(ENABLE_CRYPTO)
+#define ENABLE_PUSH_PEER_INFO
+#endif
+
+/*
+ * Compression support
+ */
+#if defined(ENABLE_LZO) || defined(ENABLE_LZ4)    \
+    || defined(ENABLE_COMP_STUB)
+#define USE_COMP
+#endif
+
+/*
+ * Enable --memstats option
+ */
+#ifdef TARGET_LINUX
+#define ENABLE_MEMSTATS
+#endif
+
+#endif /* ifndef SYSHEAD_H */
diff --git a/src/openvpn/tls_crypt.c b/src/openvpn/tls_crypt.c
new file mode 100644
index 0000000..ecc654e
--- /dev/null
+++ b/src/openvpn/tls_crypt.c
@@ -0,0 +1,269 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2016-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef ENABLE_CRYPTO
+#include "crypto.h"
+#include "session_id.h"
+
+#include "tls_crypt.h"
+
+static struct key_type
+tls_crypt_kt(void)
+{
+    struct key_type kt;
+    kt.cipher = cipher_kt_get("AES-256-CTR");
+    kt.digest = md_kt_get("SHA256");
+
+    if (!kt.cipher)
+    {
+        msg(M_WARN, "ERROR: --tls-crypt requires AES-256-CTR support.");
+        return (struct key_type) { 0 };
+    }
+    if (!kt.digest)
+    {
+        msg(M_WARN, "ERROR: --tls-crypt requires HMAC-SHA-256 support.");
+        return (struct key_type) { 0 };
+    }
+
+    kt.cipher_length = cipher_kt_key_size(kt.cipher);
+    kt.hmac_length = md_kt_size(kt.digest);
+
+    return kt;
+}
+
+int
+tls_crypt_buf_overhead(void)
+{
+    return packet_id_size(true) + TLS_CRYPT_TAG_SIZE + TLS_CRYPT_BLOCK_SIZE;
+}
+
+void
+tls_crypt_init_key(struct key_ctx_bi *key, const char *key_file,
+                   const char *key_inline, bool tls_server)
+{
+    const int key_direction = tls_server ?
+                              KEY_DIRECTION_NORMAL : KEY_DIRECTION_INVERSE;
+    struct key_type kt = tls_crypt_kt();
+    if (!kt.cipher || !kt.digest)
+    {
+        msg (M_FATAL, "ERROR: --tls-crypt not supported");
+    }
+    crypto_read_openvpn_key(&kt, key, key_file, key_inline, key_direction,
+                            "Control Channel Encryption", "tls-crypt");
+}
+
+void
+tls_crypt_adjust_frame_parameters(struct frame *frame)
+{
+    frame_add_to_extra_frame(frame, tls_crypt_buf_overhead());
+
+    msg(D_MTU_DEBUG, "%s: Adjusting frame parameters for tls-crypt by %i bytes",
+        __func__, tls_crypt_buf_overhead());
+}
+
+
+bool
+tls_crypt_wrap(const struct buffer *src, struct buffer *dst,
+               struct crypto_options *opt)
+{
+    const struct key_ctx *ctx = &opt->key_ctx_bi.encrypt;
+    struct gc_arena gc;
+
+    /* IV, packet-ID and implicit IV required for this mode. */
+    ASSERT(ctx->cipher);
+    ASSERT(ctx->hmac);
+    ASSERT(packet_id_initialized(&opt->packet_id));
+    ASSERT(hmac_ctx_size(ctx->hmac) == 256/8);
+
+    gc_init(&gc);
+
+    dmsg(D_PACKET_CONTENT, "TLS-CRYPT WRAP FROM: %s",
+         format_hex(BPTR(src), BLEN(src), 80, &gc));
+
+    /* Get packet ID */
+    if (!packet_id_write(&opt->packet_id.send, dst, true, false))
+    {
+        msg(D_CRYPT_ERRORS, "TLS-CRYPT ERROR: packet ID roll over.");
+        goto err;
+    }
+
+    dmsg(D_PACKET_CONTENT, "TLS-CRYPT WRAP AD: %s",
+         format_hex(BPTR(dst), BLEN(dst), 0, &gc));
+
+    /* Buffer overflow check */
+    if (!buf_safe(dst, BLEN(src) + TLS_CRYPT_BLOCK_SIZE + TLS_CRYPT_TAG_SIZE))
+    {
+        msg(D_CRYPT_ERRORS, "TLS-CRYPT WRAP: buffer size error, "
+            "sc=%d so=%d sl=%d dc=%d do=%d dl=%d", src->capacity, src->offset,
+            src->len, dst->capacity, dst->offset, dst->len);
+        goto err;
+    }
+
+    /* Calculate auth tag and synthetic IV */
+    {
+        uint8_t *tag = NULL;
+        hmac_ctx_reset(ctx->hmac);
+        hmac_ctx_update(ctx->hmac, BPTR(dst), BLEN(dst));
+        hmac_ctx_update(ctx->hmac, BPTR(src), BLEN(src));
+
+        ASSERT(tag = buf_write_alloc(dst, TLS_CRYPT_TAG_SIZE));
+        hmac_ctx_final(ctx->hmac, tag);
+
+        dmsg(D_PACKET_CONTENT, "TLS-CRYPT WRAP TAG: %s",
+             format_hex(tag, TLS_CRYPT_TAG_SIZE, 0, &gc));
+
+        /* Use the 128 most significant bits of the tag as IV */
+        ASSERT(cipher_ctx_reset(ctx->cipher, tag));
+    }
+
+    /* Encrypt src */
+    {
+        int outlen = 0;
+        ASSERT(cipher_ctx_update(ctx->cipher, BEND(dst), &outlen,
+                                 BPTR(src), BLEN(src)));
+        ASSERT(buf_inc_len(dst, outlen));
+        ASSERT(cipher_ctx_final(ctx->cipher, BPTR(dst), &outlen));
+        ASSERT(buf_inc_len(dst, outlen));
+    }
+
+    dmsg(D_PACKET_CONTENT, "TLS-CRYPT WRAP TO: %s",
+         format_hex(BPTR(dst), BLEN(dst), 80, &gc));
+
+    gc_free(&gc);
+    return true;
+
+err:
+    crypto_clear_error();
+    dst->len = 0;
+    gc_free(&gc);
+    return false;
+}
+
+bool
+tls_crypt_unwrap(const struct buffer *src, struct buffer *dst,
+                 struct crypto_options *opt)
+{
+    static const char error_prefix[] = "tls-crypt unwrap error";
+    const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+    struct gc_arena gc;
+
+    gc_init(&gc);
+
+    ASSERT(opt);
+    ASSERT(src->len > 0);
+    ASSERT(ctx->cipher);
+    ASSERT(packet_id_initialized(&opt->packet_id)
+           || (opt->flags & CO_IGNORE_PACKET_ID));
+
+    dmsg(D_PACKET_CONTENT, "TLS-CRYPT UNWRAP FROM: %s",
+         format_hex(BPTR(src), BLEN(src), 80, &gc));
+
+    if (buf_len(src) < TLS_CRYPT_OFF_CT)
+    {
+        CRYPT_ERROR("packet too short");
+    }
+
+    /* Decrypt cipher text */
+    {
+        int outlen = 0;
+
+        /* Buffer overflow check (should never fail) */
+        if (!buf_safe(dst, BLEN(src) - TLS_CRYPT_OFF_CT + TLS_CRYPT_BLOCK_SIZE))
+        {
+            CRYPT_ERROR("potential buffer overflow");
+        }
+
+        if (!cipher_ctx_reset(ctx->cipher, BPTR(src) + TLS_CRYPT_OFF_TAG))
+        {
+            CRYPT_ERROR("cipher reset failed");
+        }
+        if (!cipher_ctx_update(ctx->cipher, BPTR(dst), &outlen,
+                               BPTR(src) + TLS_CRYPT_OFF_CT, BLEN(src) - TLS_CRYPT_OFF_CT))
+        {
+            CRYPT_ERROR("cipher update failed");
+        }
+        ASSERT(buf_inc_len(dst, outlen));
+        if (!cipher_ctx_final(ctx->cipher, BPTR(dst), &outlen))
+        {
+            CRYPT_ERROR("cipher final failed");
+        }
+        ASSERT(buf_inc_len(dst, outlen));
+    }
+
+    /* Check authentication */
+    {
+        const uint8_t *tag = BPTR(src) + TLS_CRYPT_OFF_TAG;
+        uint8_t tag_check[TLS_CRYPT_TAG_SIZE] = { 0 };
+
+        dmsg(D_PACKET_CONTENT, "TLS-CRYPT UNWRAP AD: %s",
+             format_hex(BPTR(src), TLS_CRYPT_OFF_TAG, 0, &gc));
+        dmsg(D_PACKET_CONTENT, "TLS-CRYPT UNWRAP TO: %s",
+             format_hex(BPTR(dst), BLEN(dst), 80, &gc));
+
+        hmac_ctx_reset(ctx->hmac);
+        hmac_ctx_update(ctx->hmac, BPTR(src), TLS_CRYPT_OFF_TAG);
+        hmac_ctx_update(ctx->hmac, BPTR(dst), BLEN(dst));
+        hmac_ctx_final(ctx->hmac, tag_check);
+
+        if (memcmp_constant_time(tag, tag_check, sizeof(tag_check)))
+        {
+            dmsg(D_CRYPTO_DEBUG, "tag      : %s",
+                 format_hex(tag, sizeof(tag_check), 0, &gc));
+            dmsg(D_CRYPTO_DEBUG, "tag_check: %s",
+                 format_hex(tag_check, sizeof(tag_check), 0, &gc));
+            CRYPT_ERROR("packet authentication failed");
+        }
+    }
+
+    /* Check replay */
+    if (!(opt->flags & CO_IGNORE_PACKET_ID))
+    {
+        struct packet_id_net pin;
+        struct buffer tmp = *src;
+        ASSERT(buf_advance(&tmp, TLS_CRYPT_OFF_PID));
+        ASSERT(packet_id_read(&pin, &tmp, true));
+        if (!crypto_check_replay(opt, &pin, error_prefix, &gc))
+        {
+            CRYPT_ERROR("packet replay");
+        }
+    }
+
+    gc_free(&gc);
+    return true;
+
+error_exit:
+    crypto_clear_error();
+    dst->len = 0;
+    gc_free(&gc);
+    return false;
+}
+
+#endif /* EMABLE_CRYPTO */
diff --git a/src/openvpn/tls_crypt.h b/src/openvpn/tls_crypt.h
new file mode 100644
index 0000000..05fcc4e
--- /dev/null
+++ b/src/openvpn/tls_crypt.h
@@ -0,0 +1,147 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2016-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @defgroup tls_crypt Control channel encryption (--tls-crypt)
+ * @ingroup control_tls
+ * @{
+ *
+ * @par
+ * Control channel encryption uses a pre-shared static key (like the --tls-auth
+ * key) to encrypt control channel packets.
+ *
+ * @par
+ * Encrypting control channel packets has three main advantages:
+ *  - It provides more privacy by hiding the certificate used for the TLS
+ *    connection.
+ *  - It is harder to identify OpenVPN traffic as such.
+ *  - It provides "poor-man's" post-quantum security, against attackers who
+ *    will never know the pre-shared key (i.e. no forward secrecy).
+ *
+ * @par Specification
+ * Control channel encryption is based on the SIV construction [0], to achieve
+ * nonce misuse-resistant authenticated encryption:
+ *
+ * @par
+ * \code{.unparsed}
+ * msg      = control channel plaintext
+ * header   = opcode (1 byte) || session_id (8 bytes) || packet_id (8 bytes)
+ * Ka       = authentication key (256 bits)
+ * Ke       = encryption key (256 bits)
+ * (Ka and Ke are pre-shared keys, like with --tls-auth)
+ *
+ * auth_tag = HMAC-SHA256(Ka, header || msg)
+ * IV       = 128 most-significant bits of auth_tag
+ * ciph     = AES256-CTR(Ke, IV, msg)
+ *
+ * output   = Header || Tag || Ciph
+ * \endcode
+ *
+ * @par
+ * This boils down to the following on-the-wire packet format:
+ *
+ * @par
+ * \code{.unparsed}
+ * - opcode - || - session_id - || - packet_id - || auth_tag || * payload *
+ * \endcode
+ *
+ * @par
+ * Where
+ * <tt>- XXX -</tt> means authenticated, and
+ * <tt>* XXX *</tt> means authenticated and encrypted.
+ */
+
+#ifndef TLSCRYPT_H
+#define TLSCRYPT_H
+
+#ifdef ENABLE_CRYPTO
+
+#include "buffer.h"
+#include "crypto.h"
+#include "session_id.h"
+
+#define TLS_CRYPT_TAG_SIZE (256/8)
+#define TLS_CRYPT_PID_SIZE (sizeof(packet_id_type) + sizeof(net_time_t))
+#define TLS_CRYPT_BLOCK_SIZE (128/8)
+
+#define TLS_CRYPT_OFF_PID (1 + SID_SIZE)
+#define TLS_CRYPT_OFF_TAG (TLS_CRYPT_OFF_PID + TLS_CRYPT_PID_SIZE)
+#define TLS_CRYPT_OFF_CT (TLS_CRYPT_OFF_TAG + TLS_CRYPT_TAG_SIZE)
+
+/**
+ * Initialize a key_ctx_bi structure for use with --tls-crypt.
+ *
+ * @param key           The key context to initialize
+ * @param key_file      The file to read the key from (or the inline tag to
+ *                      indicate and inline key).
+ * @param key_inline    Array containing (zero-terminated) inline key, or NULL
+ *                      if not used.
+ * @param tls_server    Must be set to true is this is a TLS server instance.
+ */
+void tls_crypt_init_key(struct key_ctx_bi *key, const char *key_file,
+                        const char *key_inline, bool tls_server);
+
+/**
+ * Returns the maximum overhead (in bytes) added to the destination buffer by
+ * tls_crypt_wrap().
+ */
+int tls_crypt_buf_overhead(void);
+
+/**
+ * Adjust frame parameters for --tls-crypt overhead.
+ */
+void tls_crypt_adjust_frame_parameters(struct frame *frame);
+
+/**
+ * Wrap a control channel packet (both authenticates and encrypts the data).
+ *
+ * @param src   Data to authenticate and encrypt.
+ * @param dst   Any data present in this buffer is first authenticated, then
+ *              the wrapped packet id and data from the src buffer are appended.
+ *              Must have at least tls_crypt_buf_overhead()+BLEN(src) headroom.
+ * @param opt   The crypto state for this --tls-crypt instance.
+ *
+ * @returns true iff wrapping succeeded.
+ */
+bool tls_crypt_wrap(const struct buffer *src, struct buffer *dst,
+                    struct crypto_options *opt);
+
+/**
+ * Unwrap a control channel packet (decrypts, authenticates and performs
+ * replay checks).
+ *
+ * @param src   Data to decrypt and authenticate.
+ * @param dst   Returns the decrypted data, if unwrapping was successful.
+ * @param opt   The crypto state for this --tls-crypt instance.
+ *
+ * @returns true iff unwrapping succeeded (data authenticated correctly and was
+ * no replay).
+ */
+bool tls_crypt_unwrap(const struct buffer *src, struct buffer *dst,
+                      struct crypto_options *opt);
+
+/** @} */
+
+#endif /* ENABLE_CRYPTO */
+
+#endif /* TLSCRYPT_H */
diff --git a/src/openvpn/tun.c b/src/openvpn/tun.c
new file mode 100644
index 0000000..80eaa2c
--- /dev/null
+++ b/src/openvpn/tun.c
@@ -0,0 +1,6442 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Support routines for configuring and accessing TUN/TAP
+ * virtual network adapters.
+ *
+ * This file is based on the TUN/TAP driver interface routines
+ * from VTun by Maxim Krasnyansky <max_mk@yahoo.com>.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#include "tun.h"
+#include "fdmisc.h"
+#include "common.h"
+#include "misc.h"
+#include "socket.h"
+#include "manage.h"
+#include "route.h"
+#include "win32.h"
+#include "block_dns.h"
+
+#include "memdbg.h"
+
+#ifdef _WIN32
+#include "openvpn-msg.h"
+#endif
+
+#include <string.h>
+
+#ifdef _WIN32
+
+/* #define SIMULATE_DHCP_FAILED */       /* simulate bad DHCP negotiation */
+
+#define NI_TEST_FIRST  (1<<0)
+#define NI_IP_NETMASK  (1<<1)
+#define NI_OPTIONS     (1<<2)
+
+static void netsh_ifconfig(const struct tuntap_options *to,
+                           const char *flex_name,
+                           const in_addr_t ip,
+                           const in_addr_t netmask,
+                           const unsigned int flags);
+
+static void netsh_set_dns6_servers(const struct in6_addr *addr_list,
+                                   const int addr_len,
+                                   const char *flex_name);
+
+static void netsh_command(const struct argv *a, int n, int msglevel);
+
+static const char *netsh_get_id(const char *dev_node, struct gc_arena *gc);
+
+static DWORD get_adapter_index_flexible(const char *name);
+
+static bool
+do_address_service(const bool add, const short family, const struct tuntap *tt)
+{
+    DWORD len;
+    bool ret = false;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+    HANDLE pipe = tt->options.msg_channel;
+
+    address_message_t addr = {
+        .header = {
+            (add ? msg_add_address : msg_del_address),
+            sizeof(address_message_t),
+            0
+        },
+        .family = family,
+        .iface = { .index = tt->adapter_index, .name = "" }
+    };
+
+    if (addr.iface.index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        strncpy(addr.iface.name, tt->actual_name, sizeof(addr.iface.name));
+        addr.iface.name[sizeof(addr.iface.name) - 1] = '\0';
+    }
+
+    if (addr.family == AF_INET)
+    {
+        addr.address.ipv4.s_addr = tt->local;
+        addr.prefix_len = 32;
+    }
+    else
+    {
+        addr.address.ipv6 = tt->local_ipv6;
+        addr.prefix_len = tt->netbits_ipv6;
+    }
+
+    if (!WriteFile(pipe, &addr, sizeof(addr), &len, NULL)
+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "TUN: could not talk to service: %s [%lu]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+        goto out;
+    }
+
+    if (ack.error_number != NO_ERROR)
+    {
+        msg(M_WARN, "TUN: %s address failed using service: %s [status=%u if_index=%d]",
+            (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc),
+            ack.error_number, addr.iface.index);
+        goto out;
+    }
+
+    ret = true;
+
+out:
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+do_dns6_service(bool add, const struct tuntap *tt)
+{
+    DWORD len;
+    bool ret = false;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+    HANDLE pipe = tt->options.msg_channel;
+    int addr_len = add ? tt->options.dns6_len : 0;
+
+    if (addr_len == 0 && add) /* no addresses to add */
+    {
+        return true;
+    }
+
+    dns_cfg_message_t dns = {
+        .header = {
+            (add ? msg_add_dns_cfg : msg_del_dns_cfg),
+            sizeof(dns_cfg_message_t),
+            0
+        },
+        .iface = { .index = tt->adapter_index, .name = "" },
+        .domains = "",
+        .family = AF_INET6,
+        .addr_len = addr_len
+    };
+
+    /* interface name is required */
+    strncpy(dns.iface.name, tt->actual_name, sizeof(dns.iface.name));
+    dns.iface.name[sizeof(dns.iface.name) - 1] = '\0';
+
+    if (addr_len > _countof(dns.addr))
+    {
+        addr_len = _countof(dns.addr);
+        dns.addr_len = addr_len;
+        msg(M_WARN, "Number of IPv6 DNS addresses sent to service truncated to %d",
+            addr_len);
+    }
+
+    for (int i = 0; i < addr_len; ++i)
+    {
+        dns.addr[i].ipv6 = tt->options.dns6[i];
+    }
+
+    msg(D_LOW, "%s IPv6 dns servers on '%s' (if_index = %d) using service",
+        (add ? "Setting" : "Deleting"), dns.iface.name, dns.iface.index);
+
+    if (!WriteFile(pipe, &dns, sizeof(dns), &len, NULL)
+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "TUN: could not talk to service: %s [%lu]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+        goto out;
+    }
+
+    if (ack.error_number != NO_ERROR)
+    {
+        msg(M_WARN, "TUN: %s IPv6 dns failed using service: %s [status=%u if_name=%s]",
+            (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc),
+            ack.error_number, dns.iface.name);
+        goto out;
+    }
+
+    msg(M_INFO, "IPv6 dns servers %s using service", (add ? "set" : "deleted"));
+    ret = true;
+
+out:
+    gc_free(&gc);
+    return ret;
+}
+
+#endif /* ifdef _WIN32 */
+
+#ifdef TARGET_SOLARIS
+static void solaris_error_close(struct tuntap *tt, const struct env_set *es, const char *actual, bool unplumb_inet6);
+
+#include <stropts.h>
+#endif
+
+#if defined(TARGET_DARWIN) && HAVE_NET_IF_UTUN_H
+#include <sys/kern_control.h>
+#include <net/if_utun.h>
+#include <sys/sys_domain.h>
+#endif
+
+static void clear_tuntap(struct tuntap *tuntap);
+
+bool
+is_dev_type(const char *dev, const char *dev_type, const char *match_type)
+{
+    ASSERT(match_type);
+    if (!dev)
+    {
+        return false;
+    }
+    if (dev_type)
+    {
+        return !strcmp(dev_type, match_type);
+    }
+    else
+    {
+        return !strncmp(dev, match_type, strlen(match_type));
+    }
+}
+
+int
+dev_type_enum(const char *dev, const char *dev_type)
+{
+    if (is_dev_type(dev, dev_type, "tun"))
+    {
+        return DEV_TYPE_TUN;
+    }
+    else if (is_dev_type(dev, dev_type, "tap"))
+    {
+        return DEV_TYPE_TAP;
+    }
+    else if (is_dev_type(dev, dev_type, "null"))
+    {
+        return DEV_TYPE_NULL;
+    }
+    else
+    {
+        return DEV_TYPE_UNDEF;
+    }
+}
+
+const char *
+dev_type_string(const char *dev, const char *dev_type)
+{
+    switch (dev_type_enum(dev, dev_type))
+    {
+        case DEV_TYPE_TUN:
+            return "tun";
+
+        case DEV_TYPE_TAP:
+            return "tap";
+
+        case DEV_TYPE_NULL:
+            return "null";
+
+        default:
+            return "[unknown-dev-type]";
+    }
+}
+
+/*
+ * Try to predict the actual TUN/TAP device instance name,
+ * before the device is actually opened.
+ */
+const char *
+guess_tuntap_dev(const char *dev,
+                 const char *dev_type,
+                 const char *dev_node,
+                 struct gc_arena *gc)
+{
+#ifdef _WIN32
+    const int dt = dev_type_enum(dev, dev_type);
+    if (dt == DEV_TYPE_TUN || dt == DEV_TYPE_TAP)
+    {
+        return netsh_get_id(dev_node, gc);
+    }
+#endif
+
+    /* default case */
+    return dev;
+}
+
+
+/* --ifconfig-nowarn disables some options sanity checking */
+static const char ifconfig_warn_how_to_silence[] = "(silence this warning with --ifconfig-nowarn)";
+
+/*
+ * If !tun, make sure ifconfig_remote_netmask looks
+ *  like a netmask.
+ *
+ * If tun, make sure ifconfig_remote_netmask looks
+ *  like an IPv4 address.
+ */
+static void
+ifconfig_sanity_check(bool tun, in_addr_t addr, int topology)
+{
+    struct gc_arena gc = gc_new();
+    const bool looks_like_netmask = ((addr & 0xFF000000) == 0xFF000000);
+    if (tun)
+    {
+        if (looks_like_netmask && (topology == TOP_NET30 || topology == TOP_P2P))
+        {
+            msg(M_WARN, "WARNING: Since you are using --dev tun with a point-to-point topology, the second argument to --ifconfig must be an IP address.  You are using something (%s) that looks more like a netmask. %s",
+                print_in_addr_t(addr, 0, &gc),
+                ifconfig_warn_how_to_silence);
+        }
+    }
+    else /* tap */
+    {
+        if (!looks_like_netmask)
+        {
+            msg(M_WARN, "WARNING: Since you are using --dev tap, the second argument to --ifconfig must be a netmask, for example something like 255.255.255.0. %s",
+                ifconfig_warn_how_to_silence);
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * For TAP-style devices, generate a broadcast address.
+ */
+static in_addr_t
+generate_ifconfig_broadcast_addr(in_addr_t local,
+                                 in_addr_t netmask)
+{
+    return local | ~netmask;
+}
+
+/*
+ * Check that --local and --remote addresses do not
+ * clash with ifconfig addresses or subnet.
+ */
+static void
+check_addr_clash(const char *name,
+                 int type,
+                 in_addr_t public,
+                 in_addr_t local,
+                 in_addr_t remote_netmask)
+{
+    struct gc_arena gc = gc_new();
+#if 0
+    msg(M_INFO, "CHECK_ADDR_CLASH type=%d public=%s local=%s, remote_netmask=%s",
+        type,
+        print_in_addr_t(public, 0, &gc),
+        print_in_addr_t(local, 0, &gc),
+        print_in_addr_t(remote_netmask, 0, &gc));
+#endif
+
+    if (public)
+    {
+        if (type == DEV_TYPE_TUN)
+        {
+            const in_addr_t test_netmask = 0xFFFFFF00;
+            const in_addr_t public_net = public & test_netmask;
+            const in_addr_t local_net = local & test_netmask;
+            const in_addr_t remote_net = remote_netmask & test_netmask;
+
+            if (public == local || public == remote_netmask)
+            {
+                msg(M_WARN,
+                    "WARNING: --%s address [%s] conflicts with --ifconfig address pair [%s, %s]. %s",
+                    name,
+                    print_in_addr_t(public, 0, &gc),
+                    print_in_addr_t(local, 0, &gc),
+                    print_in_addr_t(remote_netmask, 0, &gc),
+                    ifconfig_warn_how_to_silence);
+            }
+
+            if (public_net == local_net || public_net == remote_net)
+            {
+                msg(M_WARN,
+                    "WARNING: potential conflict between --%s address [%s] and --ifconfig address pair [%s, %s] -- this is a warning only that is triggered when local/remote addresses exist within the same /24 subnet as --ifconfig endpoints. %s",
+                    name,
+                    print_in_addr_t(public, 0, &gc),
+                    print_in_addr_t(local, 0, &gc),
+                    print_in_addr_t(remote_netmask, 0, &gc),
+                    ifconfig_warn_how_to_silence);
+            }
+        }
+        else if (type == DEV_TYPE_TAP)
+        {
+            const in_addr_t public_network = public & remote_netmask;
+            const in_addr_t virtual_network = local & remote_netmask;
+            if (public_network == virtual_network)
+            {
+                msg(M_WARN,
+                    "WARNING: --%s address [%s] conflicts with --ifconfig subnet [%s, %s] -- local and remote addresses cannot be inside of the --ifconfig subnet. %s",
+                    name,
+                    print_in_addr_t(public, 0, &gc),
+                    print_in_addr_t(local, 0, &gc),
+                    print_in_addr_t(remote_netmask, 0, &gc),
+                    ifconfig_warn_how_to_silence);
+            }
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Issue a warning if ip/netmask (on the virtual IP network) conflicts with
+ * the settings on the local LAN.  This is designed to flag issues where
+ * (for example) the OpenVPN server LAN is running on 192.168.1.x, but then
+ * an OpenVPN client tries to connect from a public location that is also running
+ * off of a router set to 192.168.1.x.
+ */
+void
+check_subnet_conflict(const in_addr_t ip,
+                      const in_addr_t netmask,
+                      const char *prefix)
+{
+#if 0 /* too many false positives */
+    struct gc_arena gc = gc_new();
+    in_addr_t lan_gw = 0;
+    in_addr_t lan_netmask = 0;
+
+    if (get_default_gateway(&lan_gw, &lan_netmask) && lan_netmask)
+    {
+        const in_addr_t lan_network = lan_gw & lan_netmask;
+        const in_addr_t network = ip & netmask;
+
+        /* do the two subnets defined by network/netmask and lan_network/lan_netmask intersect? */
+        if ((network & lan_netmask) == lan_network
+            || (lan_network & netmask) == network)
+        {
+            msg(M_WARN, "WARNING: potential %s subnet conflict between local LAN [%s/%s] and remote VPN [%s/%s]",
+                prefix,
+                print_in_addr_t(lan_network, 0, &gc),
+                print_in_addr_t(lan_netmask, 0, &gc),
+                print_in_addr_t(network, 0, &gc),
+                print_in_addr_t(netmask, 0, &gc));
+        }
+    }
+    gc_free(&gc);
+#endif /* if 0 */
+}
+
+void
+warn_on_use_of_common_subnets(void)
+{
+    struct gc_arena gc = gc_new();
+    struct route_gateway_info rgi;
+    const int needed = (RGI_ADDR_DEFINED|RGI_NETMASK_DEFINED);
+
+    get_default_gateway(&rgi);
+    if ((rgi.flags & needed) == needed)
+    {
+        const in_addr_t lan_network = rgi.gateway.addr & rgi.gateway.netmask;
+        if (lan_network == 0xC0A80000 || lan_network == 0xC0A80100)
+        {
+            msg(M_WARN, "NOTE: your local LAN uses the extremely common subnet address 192.168.0.x or 192.168.1.x.  Be aware that this might create routing conflicts if you connect to the VPN server from public locations such as internet cafes that use the same subnet.");
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Return a string to be used for options compatibility check
+ * between peers.
+ */
+const char *
+ifconfig_options_string(const struct tuntap *tt, bool remote, bool disable, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    if (tt->did_ifconfig_setup && !disable)
+    {
+        if (tt->type == DEV_TYPE_TAP || (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET))
+        {
+            buf_printf(&out, "%s %s",
+                       print_in_addr_t(tt->local & tt->remote_netmask, 0, gc),
+                       print_in_addr_t(tt->remote_netmask, 0, gc));
+        }
+        else if (tt->type == DEV_TYPE_TUN)
+        {
+            const char *l, *r;
+            if (remote)
+            {
+                r = print_in_addr_t(tt->local, 0, gc);
+                l = print_in_addr_t(tt->remote_netmask, 0, gc);
+            }
+            else
+            {
+                l = print_in_addr_t(tt->local, 0, gc);
+                r = print_in_addr_t(tt->remote_netmask, 0, gc);
+            }
+            buf_printf(&out, "%s %s", r, l);
+        }
+        else
+        {
+            buf_printf(&out, "[undef]");
+        }
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Return a status string describing wait state.
+ */
+const char *
+tun_stat(const struct tuntap *tt, unsigned int rwflags, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(64, gc);
+    if (tt)
+    {
+        if (rwflags & EVENT_READ)
+        {
+            buf_printf(&out, "T%s",
+                       (tt->rwflags_debug & EVENT_READ) ? "R" : "r");
+#ifdef _WIN32
+            buf_printf(&out, "%s",
+                       overlapped_io_state_ascii(&tt->reads));
+#endif
+        }
+        if (rwflags & EVENT_WRITE)
+        {
+            buf_printf(&out, "T%s",
+                       (tt->rwflags_debug & EVENT_WRITE) ? "W" : "w");
+#ifdef _WIN32
+            buf_printf(&out, "%s",
+                       overlapped_io_state_ascii(&tt->writes));
+#endif
+        }
+    }
+    else
+    {
+        buf_printf(&out, "T?");
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Return true for point-to-point topology, false for subnet topology
+ */
+bool
+is_tun_p2p(const struct tuntap *tt)
+{
+    bool tun = false;
+
+    if (tt->type == DEV_TYPE_TAP
+          || (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+          || tt->type == DEV_TYPE_NULL )
+    {
+        tun = false;
+    }
+    else if (tt->type == DEV_TYPE_TUN)
+    {
+        tun = true;
+    }
+    else
+    {
+        msg(M_FATAL, "Error: problem with tun vs. tap setting"); /* JYFIXME -- needs to be caught earlier, in init_tun? */
+
+    }
+    return tun;
+}
+
+/*
+ * Set the ifconfig_* environment variables, both for IPv4 and IPv6
+ */
+void
+do_ifconfig_setenv(const struct tuntap *tt, struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    const char *ifconfig_local = print_in_addr_t(tt->local, 0, &gc);
+    const char *ifconfig_remote_netmask = print_in_addr_t(tt->remote_netmask, 0, &gc);
+
+    /*
+     * Set environmental variables with ifconfig parameters.
+     */
+    if (tt->did_ifconfig_setup)
+    {
+        bool tun = is_tun_p2p(tt);
+
+        setenv_str(es, "ifconfig_local", ifconfig_local);
+        if (tun)
+        {
+            setenv_str(es, "ifconfig_remote", ifconfig_remote_netmask);
+        }
+        else
+        {
+            const char *ifconfig_broadcast = print_in_addr_t(tt->broadcast, 0, &gc);
+            setenv_str(es, "ifconfig_netmask", ifconfig_remote_netmask);
+            setenv_str(es, "ifconfig_broadcast", ifconfig_broadcast);
+        }
+    }
+
+    if (tt->did_ifconfig_ipv6_setup)
+    {
+        const char *ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0, &gc);
+        const char *ifconfig_ipv6_remote = print_in6_addr(tt->remote_ipv6, 0, &gc);
+
+        setenv_str(es, "ifconfig_ipv6_local", ifconfig_ipv6_local);
+        setenv_int(es, "ifconfig_ipv6_netbits", tt->netbits_ipv6);
+        setenv_str(es, "ifconfig_ipv6_remote", ifconfig_ipv6_remote);
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Init tun/tap object.
+ *
+ * Set up tuntap structure for ifconfig,
+ * but don't execute yet.
+ */
+struct tuntap *
+init_tun(const char *dev,        /* --dev option */
+         const char *dev_type,   /* --dev-type option */
+         int topology,           /* one of the TOP_x values */
+         const char *ifconfig_local_parm,           /* --ifconfig parm 1 */
+         const char *ifconfig_remote_netmask_parm,  /* --ifconfig parm 2 */
+         const char *ifconfig_ipv6_local_parm,      /* --ifconfig parm 1 IPv6 */
+         int ifconfig_ipv6_netbits_parm,
+         const char *ifconfig_ipv6_remote_parm,     /* --ifconfig parm 2 IPv6 */
+         struct addrinfo *local_public,
+         struct addrinfo *remote_public,
+         const bool strict_warn,
+         struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+    struct tuntap *tt;
+
+    ALLOC_OBJ(tt, struct tuntap);
+    clear_tuntap(tt);
+
+    tt->type = dev_type_enum(dev, dev_type);
+    tt->topology = topology;
+
+    if (ifconfig_local_parm && ifconfig_remote_netmask_parm)
+    {
+        bool tun = false;
+
+        /*
+         * We only handle TUN/TAP devices here, not --dev null devices.
+         */
+        tun = is_tun_p2p(tt);
+
+        /*
+         * Convert arguments to binary IPv4 addresses.
+         */
+
+        tt->local = getaddr(
+            GETADDR_RESOLVE
+            | GETADDR_HOST_ORDER
+            | GETADDR_FATAL_ON_SIGNAL
+            | GETADDR_FATAL,
+            ifconfig_local_parm,
+            0,
+            NULL,
+            NULL);
+
+        tt->remote_netmask = getaddr(
+            (tun ? GETADDR_RESOLVE : 0)
+            | GETADDR_HOST_ORDER
+            | GETADDR_FATAL_ON_SIGNAL
+            | GETADDR_FATAL,
+            ifconfig_remote_netmask_parm,
+            0,
+            NULL,
+            NULL);
+
+        /*
+         * Look for common errors in --ifconfig parms
+         */
+        if (strict_warn)
+        {
+            struct addrinfo *curele;
+            ifconfig_sanity_check(tt->type == DEV_TYPE_TUN, tt->remote_netmask, tt->topology);
+
+            /*
+             * If local_public or remote_public addresses are defined,
+             * make sure they do not clash with our virtual subnet.
+             */
+
+            for (curele = local_public; curele; curele = curele->ai_next)
+            {
+                if (curele->ai_family == AF_INET)
+                {
+                    check_addr_clash("local",
+                                     tt->type,
+                                     ((struct sockaddr_in *)curele->ai_addr)->sin_addr.s_addr,
+                                     tt->local,
+                                     tt->remote_netmask);
+                }
+            }
+
+            for (curele = remote_public; curele; curele = curele->ai_next)
+            {
+                if (curele->ai_family == AF_INET)
+                {
+                    check_addr_clash("remote",
+                                     tt->type,
+                                     ((struct sockaddr_in *)curele->ai_addr)->sin_addr.s_addr,
+                                     tt->local,
+                                     tt->remote_netmask);
+                }
+            }
+
+            if (tt->type == DEV_TYPE_TAP || (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET))
+            {
+                check_subnet_conflict(tt->local, tt->remote_netmask, "TUN/TAP adapter");
+            }
+            else if (tt->type == DEV_TYPE_TUN)
+            {
+                check_subnet_conflict(tt->local, IPV4_NETMASK_HOST, "TUN/TAP adapter");
+            }
+        }
+
+        /*
+         * If TAP-style interface, generate broadcast address.
+         */
+        if (!tun)
+        {
+            tt->broadcast = generate_ifconfig_broadcast_addr(tt->local, tt->remote_netmask);
+        }
+
+#ifdef _WIN32
+        /*
+         * Make sure that both ifconfig addresses are part of the
+         * same .252 subnet.
+         */
+        if (tun)
+        {
+            verify_255_255_255_252(tt->local, tt->remote_netmask);
+            tt->adapter_netmask = ~3;
+        }
+        else
+        {
+            tt->adapter_netmask = tt->remote_netmask;
+        }
+#endif
+
+        tt->did_ifconfig_setup = true;
+    }
+
+    if (ifconfig_ipv6_local_parm && ifconfig_ipv6_remote_parm)
+    {
+
+        /*
+         * Convert arguments to binary IPv6 addresses.
+         */
+
+        if (inet_pton( AF_INET6, ifconfig_ipv6_local_parm, &tt->local_ipv6 ) != 1
+            || inet_pton( AF_INET6, ifconfig_ipv6_remote_parm, &tt->remote_ipv6 ) != 1)
+        {
+            msg( M_FATAL, "init_tun: problem converting IPv6 ifconfig addresses %s and %s to binary", ifconfig_ipv6_local_parm, ifconfig_ipv6_remote_parm );
+        }
+        tt->netbits_ipv6 = ifconfig_ipv6_netbits_parm;
+
+        tt->did_ifconfig_ipv6_setup = true;
+    }
+
+    /*
+     * Set environmental variables with ifconfig parameters.
+     */
+    if (es)
+    {
+        do_ifconfig_setenv(tt, es);
+    }
+
+    gc_free(&gc);
+    return tt;
+}
+
+/*
+ * Platform specific tun initializations
+ */
+void
+init_tun_post(struct tuntap *tt,
+              const struct frame *frame,
+              const struct tuntap_options *options)
+{
+    tt->options = *options;
+#ifdef _WIN32
+    overlapped_io_init(&tt->reads, frame, FALSE, true);
+    overlapped_io_init(&tt->writes, frame, TRUE, true);
+    tt->rw_handle.read = tt->reads.overlapped.hEvent;
+    tt->rw_handle.write = tt->writes.overlapped.hEvent;
+    tt->adapter_index = TUN_ADAPTER_INDEX_INVALID;
+#endif
+}
+
+#if defined(_WIN32)    \
+    || defined(TARGET_DARWIN) || defined(TARGET_NETBSD) || defined(TARGET_OPENBSD)
+
+/* some of the platforms will auto-add a "network route" pointing
+ * to the interface on "ifconfig tunX 2001:db8::1/64", others need
+ * an extra call to "route add..."
+ * -> helper function to simplify code below
+ */
+void
+add_route_connected_v6_net(struct tuntap *tt,
+                           const struct env_set *es)
+{
+    struct route_ipv6 r6;
+
+    CLEAR(r6);
+    r6.network = tt->local_ipv6;
+    r6.netbits = tt->netbits_ipv6;
+    r6.gateway = tt->local_ipv6;
+    r6.metric  = 0;                     /* connected route */
+    r6.flags   = RT_DEFINED | RT_METRIC_DEFINED;
+    add_route_ipv6(&r6, tt, 0, es);
+}
+
+void
+delete_route_connected_v6_net(struct tuntap *tt,
+                              const struct env_set *es)
+{
+    struct route_ipv6 r6;
+
+    CLEAR(r6);
+    r6.network = tt->local_ipv6;
+    r6.netbits = tt->netbits_ipv6;
+    r6.gateway = tt->local_ipv6;
+    r6.metric  = 0;                     /* connected route */
+    r6.flags   = RT_DEFINED | RT_ADDED | RT_METRIC_DEFINED;
+    route_ipv6_clear_host_bits(&r6);
+    delete_route_ipv6(&r6, tt, 0, es);
+}
+#endif /* if defined(_WIN32) || defined(TARGET_DARWIN) || defined(TARGET_NETBSD) || defined(TARGET_OPENBSD) */
+
+#if defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)  \
+    || defined(TARGET_NETBSD) || defined(TARGET_OPENBSD)
+/* we can't use true subnet mode on tun on all platforms, as that
+ * conflicts with IPv6 (wants to use ND then, which we don't do),
+ * but the OSes want "a remote address that is different from ours"
+ * - so we construct one, normally the first in the subnet, but if
+ * this is the same as ours, use the second one.
+ * The actual address does not matter at all, as the tun interface
+ * is still point to point and no layer 2 resolution is done...
+ */
+
+in_addr_t
+create_arbitrary_remote( struct tuntap *tt )
+{
+    in_addr_t remote;
+
+    remote = (tt->local & tt->remote_netmask) +1;
+
+    if (remote == tt->local)
+    {
+        remote++;
+    }
+
+    return remote;
+}
+#endif
+
+/* execute the ifconfig command through the shell */
+void
+do_ifconfig(struct tuntap *tt,
+            const char *actual,     /* actual device name */
+            int tun_mtu,
+            const struct env_set *es)
+{
+    struct gc_arena gc = gc_new();
+
+    if (tt->did_ifconfig_setup)
+    {
+        bool tun = false;
+        const char *ifconfig_local = NULL;
+        const char *ifconfig_remote_netmask = NULL;
+        const char *ifconfig_broadcast = NULL;
+        const char *ifconfig_ipv6_local = NULL;
+        bool do_ipv6 = false;
+        struct argv argv = argv_new();
+
+        msg( D_LOW, "do_ifconfig, tt->did_ifconfig_ipv6_setup=%d",
+             tt->did_ifconfig_ipv6_setup );
+
+        /*
+         * We only handle TUN/TAP devices here, not --dev null devices.
+         */
+        tun = is_tun_p2p(tt);
+
+        /*
+         * Set ifconfig parameters
+         */
+        ifconfig_local = print_in_addr_t(tt->local, 0, &gc);
+        ifconfig_remote_netmask = print_in_addr_t(tt->remote_netmask, 0, &gc);
+
+        if (tt->did_ifconfig_ipv6_setup)
+        {
+            ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0, &gc);
+            do_ipv6 = true;
+        }
+
+        /*
+         * If TAP-style device, generate broadcast address.
+         */
+        if (!tun)
+        {
+            ifconfig_broadcast = print_in_addr_t(tt->broadcast, 0, &gc);
+        }
+
+#ifdef ENABLE_MANAGEMENT
+        if (management)
+        {
+            management_set_state(management,
+                                 OPENVPN_STATE_ASSIGN_IP,
+                                 NULL,
+                                 &tt->local,
+                                 &tt->local_ipv6,
+                                 NULL,
+                                 NULL);
+        }
+#endif
+
+
+#if defined(TARGET_LINUX)
+#ifdef ENABLE_IPROUTE
+        /*
+         * Set the MTU for the device
+         */
+        argv_printf(&argv,
+                    "%s link set dev %s up mtu %d",
+                    iproute_path,
+                    actual,
+                    tun_mtu
+                    );
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "Linux ip link set failed");
+
+        if (tun)
+        {
+
+            /*
+             * Set the address for the device
+             */
+            argv_printf(&argv,
+                        "%s addr add dev %s local %s peer %s",
+                        iproute_path,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "Linux ip addr add failed");
+        }
+        else
+        {
+            argv_printf(&argv,
+                        "%s addr add dev %s %s/%d broadcast %s",
+                        iproute_path,
+                        actual,
+                        ifconfig_local,
+                        netmask_to_netbits2(tt->remote_netmask),
+                        ifconfig_broadcast
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "Linux ip addr add failed");
+        }
+        if (do_ipv6)
+        {
+            argv_printf( &argv,
+                         "%s -6 addr add %s/%d dev %s",
+                         iproute_path,
+                         ifconfig_ipv6_local,
+                         tt->netbits_ipv6,
+                         actual
+                         );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "Linux ip -6 addr add failed");
+        }
+        tt->did_ifconfig = true;
+#else  /* ifdef ENABLE_IPROUTE */
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s pointopoint %s mtu %d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else
+        {
+            argv_printf(&argv,
+                        "%s %s %s netmask %s mtu %d broadcast %s",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu,
+                        ifconfig_broadcast
+                        );
+        }
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "Linux ifconfig failed");
+        if (do_ipv6)
+        {
+            argv_printf(&argv,
+                        "%s %s add %s/%d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "Linux ifconfig inet6 failed");
+        }
+        tt->did_ifconfig = true;
+
+#endif /*ENABLE_IPROUTE*/
+#elif defined(TARGET_ANDROID)
+
+        if (do_ipv6)
+        {
+            struct buffer out6 = alloc_buf_gc(64, &gc);
+            buf_printf(&out6, "%s/%d", ifconfig_ipv6_local,tt->netbits_ipv6);
+            management_android_control(management, "IFCONFIG6",buf_bptr(&out6));
+        }
+
+        struct buffer out = alloc_buf_gc(64, &gc);
+
+        char *top;
+        switch (tt->topology)
+        {
+            case TOP_NET30:
+                top = "net30";
+                break;
+
+            case TOP_P2P:
+                top = "p2p";
+                break;
+
+            case TOP_SUBNET:
+                top = "subnet";
+                break;
+
+            default:
+                top = "undef";
+        }
+
+        buf_printf(&out, "%s %s %d %s", ifconfig_local, ifconfig_remote_netmask, tun_mtu, top);
+        management_android_control(management, "IFCONFIG", buf_bptr(&out));
+
+#elif defined(TARGET_SOLARIS)
+        /* Solaris 2.6 (and 7?) cannot set all parameters in one go...
+         * example:
+         *    ifconfig tun2 10.2.0.2 10.2.0.1 mtu 1450 up
+         *    ifconfig tun2 netmask 255.255.255.255
+         */
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+
+            argv_msg(M_INFO, &argv);
+            if (!openvpn_execve_check(&argv, es, 0, "Solaris ifconfig phase-1 failed"))
+            {
+                solaris_error_close(tt, es, actual, false);
+            }
+
+            argv_printf(&argv,
+                        "%s %s netmask 255.255.255.255",
+                        IFCONFIG_PATH,
+                        actual
+                        );
+        }
+        else if (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s netmask %s mtu %d up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else
+        {
+            argv_printf(&argv,
+                        " %s %s %s netmask %s broadcast + up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask
+                        );
+        }
+
+        argv_msg(M_INFO, &argv);
+        if (!openvpn_execve_check(&argv, es, 0, "Solaris ifconfig phase-2 failed"))
+        {
+            solaris_error_close(tt, es, actual, false);
+        }
+
+        if (do_ipv6)
+        {
+            argv_printf(&argv, "%s %s inet6 unplumb",
+                        IFCONFIG_PATH, actual );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, 0, NULL);
+
+            if (tt->type == DEV_TYPE_TUN)
+            {
+                const char *ifconfig_ipv6_remote =
+                    print_in6_addr(tt->remote_ipv6, 0, &gc);
+
+                argv_printf(&argv,
+                            "%s %s inet6 plumb %s/%d %s up",
+                            IFCONFIG_PATH,
+                            actual,
+                            ifconfig_ipv6_local,
+                            tt->netbits_ipv6,
+                            ifconfig_ipv6_remote
+                            );
+            }
+            else                                        /* tap mode */
+            {
+                /* base IPv6 tap interface needs to be brought up first
+                 */
+                argv_printf(&argv, "%s %s inet6 plumb up",
+                            IFCONFIG_PATH, actual );
+                argv_msg(M_INFO, &argv);
+                if (!openvpn_execve_check(&argv, es, 0, "Solaris ifconfig IPv6 (prepare) failed"))
+                {
+                    solaris_error_close(tt, es, actual, true);
+                }
+
+                /* we might need to do "ifconfig %s inet6 auto-dhcp drop"
+                 * after the system has noticed the interface and fired up
+                 * the DHCPv6 client - but this takes quite a while, and the
+                 * server will ignore the DHCPv6 packets anyway.  So we don't.
+                 */
+
+                /* static IPv6 addresses need to go to a subinterface (tap0:1)
+                 */
+                argv_printf(&argv,
+                            "%s %s inet6 addif %s/%d up",
+                            IFCONFIG_PATH, actual,
+                            ifconfig_ipv6_local, tt->netbits_ipv6 );
+            }
+            argv_msg(M_INFO, &argv);
+            if (!openvpn_execve_check(&argv, es, 0, "Solaris ifconfig IPv6 failed"))
+            {
+                solaris_error_close(tt, es, actual, true);
+            }
+        }
+
+        if (!tun && tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            /* Add a network route for the local tun interface */
+            struct route_ipv4 r;
+            CLEAR(r);
+            r.flags = RT_DEFINED | RT_METRIC_DEFINED;
+            r.network = tt->local & tt->remote_netmask;
+            r.netmask = tt->remote_netmask;
+            r.gateway = tt->local;
+            r.metric = 0;
+            add_route(&r, tt, 0, NULL, es);
+        }
+
+        tt->did_ifconfig = true;
+
+#elif defined(TARGET_OPENBSD)
+
+        in_addr_t remote_end;           /* for "virtual" subnet topology */
+
+        /*
+         * On OpenBSD, tun interfaces are persistent if created with
+         * "ifconfig tunX create", and auto-destroyed if created by
+         * opening "/dev/tunX" (so we just use the /dev/tunX)
+         */
+
+        /* example: ifconfig tun2 10.2.0.2 10.2.0.1 mtu 1450 netmask 255.255.255.255 up */
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask 255.255.255.255 up -link0",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else if (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            remote_end = create_arbitrary_remote( tt );
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask %s up -link0",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        print_in_addr_t(remote_end, 0, &gc),
+                        tun_mtu,
+                        ifconfig_remote_netmask
+                        );
+        }
+        else
+        {
+            argv_printf(&argv,
+                        "%s %s %s netmask %s mtu %d broadcast %s link0",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu,
+                        ifconfig_broadcast
+                        );
+        }
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "OpenBSD ifconfig failed");
+
+        /* Add a network route for the local tun interface */
+        if (!tun && tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            struct route_ipv4 r;
+            CLEAR(r);
+            r.flags = RT_DEFINED;
+            r.network = tt->local & tt->remote_netmask;
+            r.netmask = tt->remote_netmask;
+            r.gateway = remote_end;
+            add_route(&r, tt, 0, NULL, es);
+        }
+
+        if (do_ipv6)
+        {
+            argv_printf(&argv,
+                        "%s %s inet6 %s/%d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "OpenBSD ifconfig inet6 failed");
+
+            /* and, hooray, we explicitely need to add a route... */
+            add_route_connected_v6_net(tt, es);
+        }
+        tt->did_ifconfig = true;
+
+#elif defined(TARGET_NETBSD)
+
+        in_addr_t remote_end;           /* for "virtual" subnet topology */
+
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask 255.255.255.255 up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else if (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            remote_end = create_arbitrary_remote( tt );
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask %s up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        print_in_addr_t(remote_end, 0, &gc),
+                        tun_mtu,
+                        ifconfig_remote_netmask
+                        );
+        }
+        else
+        {
+            /*
+             * NetBSD has distinct tun and tap devices
+             * so we don't need the "link0" extra parameter to specify we want to do
+             * tunneling at the ethernet level
+             */
+            argv_printf(&argv,
+                        "%s %s %s netmask %s mtu %d broadcast %s",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu,
+                        ifconfig_broadcast
+                        );
+        }
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "NetBSD ifconfig failed");
+
+        /* Add a network route for the local tun interface */
+        if (!tun && tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            struct route_ipv4 r;
+            CLEAR(r);
+            r.flags = RT_DEFINED;
+            r.network = tt->local & tt->remote_netmask;
+            r.netmask = tt->remote_netmask;
+            r.gateway = remote_end;
+            add_route(&r, tt, 0, NULL, es);
+        }
+
+        if (do_ipv6)
+        {
+            argv_printf(&argv,
+                        "%s %s inet6 %s/%d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "NetBSD ifconfig inet6 failed");
+
+            /* and, hooray, we explicitely need to add a route... */
+            add_route_connected_v6_net(tt, es);
+        }
+        tt->did_ifconfig = true;
+
+#elif defined(TARGET_DARWIN)
+        /*
+         * Darwin (i.e. Mac OS X) seems to exhibit similar behaviour to OpenBSD...
+         */
+
+        argv_printf(&argv,
+                    "%s %s delete",
+                    IFCONFIG_PATH,
+                    actual);
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, 0, NULL);
+        msg(M_INFO, "NOTE: Tried to delete pre-existing tun/tap instance -- No Problem if failure");
+
+
+        /* example: ifconfig tun2 10.2.0.2 10.2.0.1 mtu 1450 netmask 255.255.255.255 up */
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask 255.255.255.255 up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else
+        {
+            if (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+            {
+                argv_printf(&argv,
+                            "%s %s %s %s netmask %s mtu %d up",
+                            IFCONFIG_PATH,
+                            actual,
+                            ifconfig_local,
+                            ifconfig_local,
+                            ifconfig_remote_netmask,
+                            tun_mtu
+                            );
+            }
+            else
+            {
+                argv_printf(&argv,
+                            "%s %s %s netmask %s mtu %d up",
+                            IFCONFIG_PATH,
+                            actual,
+                            ifconfig_local,
+                            ifconfig_remote_netmask,
+                            tun_mtu
+                            );
+            }
+        }
+
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "Mac OS X ifconfig failed");
+        tt->did_ifconfig = true;
+
+        /* Add a network route for the local tun interface */
+        if (!tun && tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            struct route_ipv4 r;
+            CLEAR(r);
+            r.flags = RT_DEFINED;
+            r.network = tt->local & tt->remote_netmask;
+            r.netmask = tt->remote_netmask;
+            r.gateway = tt->local;
+            add_route(&r, tt, 0, NULL, es);
+        }
+
+        if (do_ipv6)
+        {
+            argv_printf(&argv,
+                        "%s %s inet6 %s/%d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "MacOS X ifconfig inet6 failed");
+
+            /* and, hooray, we explicitely need to add a route... */
+            add_route_connected_v6_net(tt, es);
+        }
+
+#elif defined(TARGET_FREEBSD) || defined(TARGET_DRAGONFLY)
+
+        in_addr_t remote_end;           /* for "virtual" subnet topology */
+
+        /* example: ifconfig tun2 10.2.0.2 10.2.0.1 mtu 1450 netmask 255.255.255.255 up */
+        if (tun)
+        {
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask 255.255.255.255 up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+        else if (tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            remote_end = create_arbitrary_remote( tt );
+            argv_printf(&argv,
+                        "%s %s %s %s mtu %d netmask %s up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        print_in_addr_t(remote_end, 0, &gc),
+                        tun_mtu,
+                        ifconfig_remote_netmask
+                        );
+        }
+        else
+        {
+            argv_printf(&argv,
+                        "%s %s %s netmask %s mtu %d up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+        }
+
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, S_FATAL, "FreeBSD ifconfig failed");
+        tt->did_ifconfig = true;
+
+        /* Add a network route for the local tun interface */
+        if (!tun && tt->type == DEV_TYPE_TUN && tt->topology == TOP_SUBNET)
+        {
+            struct route_ipv4 r;
+            CLEAR(r);
+            r.flags = RT_DEFINED;
+            r.network = tt->local & tt->remote_netmask;
+            r.netmask = tt->remote_netmask;
+            r.gateway = remote_end;
+            add_route(&r, tt, 0, NULL, es);
+        }
+
+        if (do_ipv6)
+        {
+            argv_printf(&argv,
+                        "%s %s inet6 %s/%d",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_ipv6_local,
+                        tt->netbits_ipv6
+                        );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, es, S_FATAL, "FreeBSD ifconfig inet6 failed");
+        }
+
+#elif defined(TARGET_AIX)
+        {
+            /* AIX ifconfig will complain if it can't find ODM path in env */
+            struct env_set *aix_es = env_set_create(NULL);
+            env_set_add( aix_es, "ODMDIR=/etc/objrepos" );
+
+            if (tun)
+            {
+                msg(M_FATAL, "no tun support on AIX (canthappen)");
+            }
+
+            /* example: ifconfig tap0 172.30.1.1 netmask 255.255.254.0 up */
+            argv_printf(&argv,
+                        "%s %s %s netmask %s mtu %d up",
+                        IFCONFIG_PATH,
+                        actual,
+                        ifconfig_local,
+                        ifconfig_remote_netmask,
+                        tun_mtu
+                        );
+
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, aix_es, S_FATAL, "AIX ifconfig failed");
+            tt->did_ifconfig = true;
+
+            if (do_ipv6)
+            {
+                argv_printf(&argv,
+                            "%s %s inet6 %s/%d",
+                            IFCONFIG_PATH,
+                            actual,
+                            ifconfig_ipv6_local,
+                            tt->netbits_ipv6
+                            );
+                argv_msg(M_INFO, &argv);
+                openvpn_execve_check(&argv, aix_es, S_FATAL, "AIX ifconfig inet6 failed");
+            }
+            env_set_destroy(aix_es);
+        }
+#elif defined (_WIN32)
+        {
+            ASSERT(actual != NULL);
+
+            switch (tt->options.ip_win32_type)
+            {
+                case IPW32_SET_MANUAL:
+                    msg(M_INFO, "******** NOTE:  Please manually set the IP/netmask of '%s' to %s/%s (if it is not already set)",
+                        actual,
+                        ifconfig_local,
+                        print_in_addr_t(tt->adapter_netmask, 0, &gc));
+                    break;
+
+                case IPW32_SET_NETSH:
+                    netsh_ifconfig(&tt->options,
+                                   actual,
+                                   tt->local,
+                                   tt->adapter_netmask,
+                                   NI_IP_NETMASK|NI_OPTIONS);
+
+                    break;
+            }
+            tt->did_ifconfig = true;
+        }
+
+        if (do_ipv6)
+        {
+            if (tt->options.ip_win32_type == IPW32_SET_MANUAL)
+            {
+                msg(M_INFO, "******** NOTE:  Please manually set the v6 IP of '%s' to %s (if it is not already set)",
+                    actual,
+                    ifconfig_ipv6_local);
+            }
+            else if (tt->options.msg_channel)
+            {
+                do_address_service(true, AF_INET6, tt);
+                do_dns6_service(true, tt);
+            }
+            else
+            {
+                /* example: netsh interface ipv6 set address interface=42 2001:608:8003::d store=active */
+                char iface[64];
+                openvpn_snprintf(iface, sizeof(iface), "interface=%lu", tt->adapter_index );
+                argv_printf(&argv,
+                            "%s%sc interface ipv6 set address %s %s store=active",
+                            get_win_sys_path(),
+                            NETSH_PATH_SUFFIX,
+                            iface,
+                            ifconfig_ipv6_local );
+                netsh_command(&argv, 4, M_FATAL);
+                /* set ipv6 dns servers if any are specified */
+                netsh_set_dns6_servers(tt->options.dns6, tt->options.dns6_len, actual);
+            }
+
+            /* explicit route needed */
+            if (tt->options.ip_win32_type != IPW32_SET_MANUAL)
+            {
+                add_route_connected_v6_net(tt, es);
+            }
+        }
+#else  /* if defined(TARGET_LINUX) */
+        msg(M_FATAL, "Sorry, but I don't know how to do 'ifconfig' commands on this operating system.  You should ifconfig your TUN/TAP device manually or use an --up script.");
+#endif /* if defined(TARGET_LINUX) */
+        argv_reset(&argv);
+    }
+    gc_free(&gc);
+}
+
+static void
+clear_tuntap(struct tuntap *tuntap)
+{
+    CLEAR(*tuntap);
+#ifdef _WIN32
+    tuntap->hand = NULL;
+#else
+    tuntap->fd = -1;
+#endif
+#ifdef TARGET_SOLARIS
+    tuntap->ip_fd = -1;
+#endif
+}
+
+static void
+open_null(struct tuntap *tt)
+{
+    tt->actual_name = string_alloc("null", NULL);
+}
+
+
+#if defined (TARGET_OPENBSD) || (defined(TARGET_DARWIN) && HAVE_NET_IF_UTUN_H)
+
+/*
+ * OpenBSD and Mac OS X when using utun
+ * have a slightly incompatible TUN device from
+ * the rest of the world, in that it prepends a
+ * uint32 to the beginning of the IP header
+ * to designate the protocol (why not just
+ * look at the version field in the IP header to
+ * determine v4 or v6?).
+ *
+ * We strip off this field on reads and
+ * put it back on writes.
+ *
+ * I have not tested TAP devices on OpenBSD,
+ * but I have conditionalized the special
+ * TUN handling code described above to
+ * go away for TAP devices.
+ */
+
+#include <netinet/ip.h>
+#include <sys/uio.h>
+
+static inline int
+header_modify_read_write_return(int len)
+{
+    if (len > 0)
+    {
+        return len > sizeof(u_int32_t) ? len - sizeof(u_int32_t) : 0;
+    }
+    else
+    {
+        return len;
+    }
+}
+
+int
+write_tun_header(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+        struct openvpn_iphdr *iph;
+
+        iph = (struct openvpn_iphdr *) buf;
+
+        if (OPENVPN_IPH_GET_VER(iph->version_len) == 6)
+        {
+            type = htonl(AF_INET6);
+        }
+        else
+        {
+            type = htonl(AF_INET);
+        }
+
+        iv[0].iov_base = &type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return header_modify_read_write_return(writev(tt->fd, iv, 2));
+    }
+    else
+    {
+        return write(tt->fd, buf, len);
+    }
+}
+
+int
+read_tun_header(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+
+        iv[0].iov_base = &type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return header_modify_read_write_return(readv(tt->fd, iv, 2));
+    }
+    else
+    {
+        return read(tt->fd, buf, len);
+    }
+}
+#endif /* if defined (TARGET_OPENBSD) || (defined(TARGET_DARWIN) && HAVE_NET_IF_UTUN_H) */
+
+
+#if !(defined(_WIN32) || defined(TARGET_LINUX))
+static void
+open_tun_generic(const char *dev, const char *dev_type, const char *dev_node,
+                 bool dynamic, struct tuntap *tt)
+{
+    char tunname[256];
+    char dynamic_name[256];
+    bool dynamic_opened = false;
+
+    if (tt->type == DEV_TYPE_NULL)
+    {
+        open_null(tt);
+    }
+    else
+    {
+        /*
+         * --dev-node specified, so open an explicit device node
+         */
+        if (dev_node)
+        {
+            openvpn_snprintf(tunname, sizeof(tunname), "%s", dev_node);
+        }
+        else
+        {
+            /*
+             * dynamic open is indicated by --dev specified without
+             * explicit unit number.  Try opening /dev/[dev]n
+             * where n = [0, 255].
+             */
+#ifdef TARGET_NETBSD
+            /* on NetBSD, tap (but not tun) devices are opened by
+             * opening /dev/tap and then querying the system about the
+             * actual device name (tap0, tap1, ...) assigned
+             */
+            if (dynamic && strcmp( dev, "tap" ) == 0)
+            {
+                struct ifreq ifr;
+                if ((tt->fd = open( "/dev/tap", O_RDWR)) < 0)
+                {
+                    msg(M_FATAL, "Cannot allocate NetBSD TAP dev dynamically");
+                }
+                if (ioctl( tt->fd, TAPGIFNAME, (void *)&ifr ) < 0)
+                {
+                    msg(M_FATAL, "Cannot query NetBSD TAP device name");
+                }
+                CLEAR(dynamic_name);
+                strncpy( dynamic_name, ifr.ifr_name, sizeof(dynamic_name)-1 );
+                dynamic_opened = true;
+                openvpn_snprintf(tunname, sizeof(tunname), "/dev/%s", dynamic_name );
+            }
+            else
+#endif
+
+            if (dynamic && !has_digit((unsigned char *)dev))
+            {
+                int i;
+                for (i = 0; i < 256; ++i)
+                {
+                    openvpn_snprintf(tunname, sizeof(tunname),
+                                     "/dev/%s%d", dev, i);
+                    openvpn_snprintf(dynamic_name, sizeof(dynamic_name),
+                                     "%s%d", dev, i);
+                    if ((tt->fd = open(tunname, O_RDWR)) > 0)
+                    {
+                        dynamic_opened = true;
+                        break;
+                    }
+                    msg(D_READ_WRITE | M_ERRNO, "Tried opening %s (failed)", tunname);
+                }
+                if (!dynamic_opened)
+                {
+                    msg(M_FATAL, "Cannot allocate TUN/TAP dev dynamically");
+                }
+            }
+            /*
+             * explicit unit number specified
+             */
+            else
+            {
+                openvpn_snprintf(tunname, sizeof(tunname), "/dev/%s", dev);
+            }
+        }
+
+        if (!dynamic_opened)
+        {
+            /* has named device existed before? if so, don't destroy at end */
+            if (if_nametoindex( dev ) > 0)
+            {
+                msg(M_INFO, "TUN/TAP device %s exists previously, keep at program end", dev );
+                tt->persistent_if = true;
+            }
+
+            if ((tt->fd = open(tunname, O_RDWR)) < 0)
+            {
+                msg(M_ERR, "Cannot open TUN/TAP dev %s", tunname);
+            }
+        }
+
+        set_nonblock(tt->fd);
+        set_cloexec(tt->fd); /* don't pass fd to scripts */
+        msg(M_INFO, "TUN/TAP device %s opened", tunname);
+
+        /* tt->actual_name is passed to up and down scripts and used as the ifconfig dev name */
+        tt->actual_name = string_alloc(dynamic_opened ? dynamic_name : dev, NULL);
+    }
+}
+#endif /* !_WIN32 && !TARGET_LINUX */
+
+#if !defined(_WIN32)
+static void
+close_tun_generic(struct tuntap *tt)
+{
+    if (tt->fd >= 0)
+    {
+        close(tt->fd);
+    }
+    if (tt->actual_name)
+    {
+        free(tt->actual_name);
+    }
+    clear_tuntap(tt);
+}
+#endif /* !_WIN32 */
+
+#if defined (TARGET_ANDROID)
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+#define ANDROID_TUNNAME "vpnservice-tun"
+    struct user_pass up;
+    struct gc_arena gc = gc_new();
+    bool opentun;
+
+    int oldtunfd = tt->fd;
+
+    /* Prefer IPv6 DNS servers,
+     * Android will use the DNS server in the order we specify*/
+    for (int i = 0; i < tt->options.dns6_len; i++)
+    {
+        management_android_control(management, "DNS6SERVER",
+                                   print_in6_addr(tt->options.dns6[i], 0, &gc));
+    }
+
+    for (int i = 0; i < tt->options.dns_len; i++)
+    {
+        management_android_control(management, "DNSSERVER",
+                                   print_in_addr_t(tt->options.dns[i], 0, &gc));
+    }
+
+    if (tt->options.domain)
+    {
+        management_android_control(management, "DNSDOMAIN", tt->options.domain);
+    }
+
+    int android_method = managment_android_persisttun_action(management);
+
+    /* Android 4.4 workaround */
+    if (oldtunfd >=0 && android_method == ANDROID_OPEN_AFTER_CLOSE)
+    {
+        close(oldtunfd);
+        management_sleep(2);
+    }
+
+    if (oldtunfd >=0  && android_method == ANDROID_KEEP_OLD_TUN)
+    {
+        /* keep the old fd */
+        opentun = true;
+    }
+    else
+    {
+        opentun = management_android_control(management, "OPENTUN", dev);
+        /* Pick up the fd from management interface after calling the
+         * OPENTUN command */
+        tt->fd = management->connection.lastfdreceived;
+        management->connection.lastfdreceived = -1;
+    }
+
+    if (oldtunfd>=0 && android_method == ANDROID_OPEN_BEFORE_CLOSE)
+    {
+        close(oldtunfd);
+    }
+
+    /* Set the actual name to a dummy name */
+    tt->actual_name = string_alloc(ANDROID_TUNNAME, NULL);
+
+    if ((tt->fd < 0) || !opentun)
+    {
+        msg(M_ERR, "ERROR: Cannot open TUN");
+    }
+
+    gc_free(&gc);
+}
+
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return write(tt->fd, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return read(tt->fd, buf, len);
+}
+
+#elif defined(TARGET_LINUX)
+
+#ifndef HAVE_LINUX_SOCKIOS_H
+#error header file linux/sockios.h required
+#endif
+
+#if !PEDANTIC
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    struct ifreq ifr;
+
+    /*
+     * We handle --dev null specially, we do not open /dev/null for this.
+     */
+    if (tt->type == DEV_TYPE_NULL)
+    {
+        open_null(tt);
+    }
+    else
+    {
+        /*
+         * Process --dev-node
+         */
+        const char *node = dev_node;
+        if (!node)
+        {
+            node = "/dev/net/tun";
+        }
+
+        /*
+         * Open the interface
+         */
+        if ((tt->fd = open(node, O_RDWR)) < 0)
+        {
+            msg(M_ERR, "ERROR: Cannot open TUN/TAP dev %s", node);
+        }
+
+        /*
+         * Process --tun-ipv6
+         */
+        CLEAR(ifr);
+        ifr.ifr_flags = IFF_NO_PI;
+
+#if defined(IFF_ONE_QUEUE) && defined(SIOCSIFTXQLEN)
+        ifr.ifr_flags |= IFF_ONE_QUEUE;
+#endif
+
+        /*
+         * Figure out if tun or tap device
+         */
+        if (tt->type == DEV_TYPE_TUN)
+        {
+            ifr.ifr_flags |= IFF_TUN;
+        }
+        else if (tt->type == DEV_TYPE_TAP)
+        {
+            ifr.ifr_flags |= IFF_TAP;
+        }
+        else
+        {
+            msg(M_FATAL, "I don't recognize device %s as a tun or tap device",
+                dev);
+        }
+
+        /*
+         * Set an explicit name, if --dev is not tun or tap
+         */
+        if (strcmp(dev, "tun") && strcmp(dev, "tap"))
+        {
+            strncpynt(ifr.ifr_name, dev, IFNAMSIZ);
+        }
+
+        /*
+         * Use special ioctl that configures tun/tap device with the parms
+         * we set in ifr
+         */
+        if (ioctl(tt->fd, TUNSETIFF, (void *) &ifr) < 0)
+        {
+            msg(M_ERR, "ERROR: Cannot ioctl TUNSETIFF %s", dev);
+        }
+
+        msg(M_INFO, "TUN/TAP device %s opened", ifr.ifr_name);
+
+        /*
+         * Try making the TX send queue bigger
+         */
+#if defined(IFF_ONE_QUEUE) && defined(SIOCSIFTXQLEN)
+        if (tt->options.txqueuelen)
+        {
+            struct ifreq netifr;
+            int ctl_fd;
+
+            if ((ctl_fd = socket(AF_INET, SOCK_DGRAM, 0)) >= 0)
+            {
+                CLEAR(netifr);
+                strncpynt(netifr.ifr_name, ifr.ifr_name, IFNAMSIZ);
+                netifr.ifr_qlen = tt->options.txqueuelen;
+                if (ioctl(ctl_fd, SIOCSIFTXQLEN, (void *) &netifr) >= 0)
+                {
+                    msg(D_OSBUF, "TUN/TAP TX queue length set to %d", tt->options.txqueuelen);
+                }
+                else
+                {
+                    msg(M_WARN | M_ERRNO, "Note: Cannot set tx queue length on %s", ifr.ifr_name);
+                }
+                close(ctl_fd);
+            }
+            else
+            {
+                msg(M_WARN | M_ERRNO, "Note: Cannot open control socket on %s", ifr.ifr_name);
+            }
+        }
+#endif /* if defined(IFF_ONE_QUEUE) && defined(SIOCSIFTXQLEN) */
+
+        set_nonblock(tt->fd);
+        set_cloexec(tt->fd);
+        tt->actual_name = string_alloc(ifr.ifr_name, NULL);
+    }
+    return;
+}
+
+#else  /* if !PEDANTIC */
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    ASSERT(0);
+}
+
+#endif /* !PENDANTIC */
+
+#ifdef ENABLE_FEATURE_TUN_PERSIST
+
+void
+tuncfg(const char *dev, const char *dev_type, const char *dev_node, int persist_mode, const char *username, const char *groupname, const struct tuntap_options *options)
+{
+    struct tuntap *tt;
+
+    ALLOC_OBJ(tt, struct tuntap);
+    clear_tuntap(tt);
+    tt->type = dev_type_enum(dev, dev_type);
+    tt->options = *options;
+    open_tun(dev, dev_type, dev_node, tt);
+    if (ioctl(tt->fd, TUNSETPERSIST, persist_mode) < 0)
+    {
+        msg(M_ERR, "Cannot ioctl TUNSETPERSIST(%d) %s", persist_mode, dev);
+    }
+    if (username != NULL)
+    {
+        struct platform_state_user platform_state_user;
+
+        if (!platform_user_get(username, &platform_state_user))
+        {
+            msg(M_ERR, "Cannot get user entry for %s", username);
+        }
+        else if (ioctl(tt->fd, TUNSETOWNER, platform_state_user.pw->pw_uid) < 0)
+        {
+            msg(M_ERR, "Cannot ioctl TUNSETOWNER(%s) %s", username, dev);
+        }
+    }
+    if (groupname != NULL)
+    {
+        struct platform_state_group platform_state_group;
+
+        if (!platform_group_get(groupname, &platform_state_group))
+        {
+            msg(M_ERR, "Cannot get group entry for %s", groupname);
+        }
+        else if (ioctl(tt->fd, TUNSETGROUP, platform_state_group.gr->gr_gid) < 0)
+        {
+            msg(M_ERR, "Cannot ioctl TUNSETOWNER(%s) %s", groupname, dev);
+        }
+    }
+    close_tun(tt);
+    msg(M_INFO, "Persist state set to: %s", (persist_mode ? "ON" : "OFF"));
+}
+
+#endif /* ENABLE_FEATURE_TUN_PERSIST */
+
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        if (tt->type != DEV_TYPE_NULL && tt->did_ifconfig)
+        {
+            struct argv argv = argv_new();
+            struct gc_arena gc = gc_new();
+
+#ifdef ENABLE_IPROUTE
+            if (is_tun_p2p(tt))
+            {
+                argv_printf(&argv,
+                            "%s addr del dev %s local %s peer %s",
+                            iproute_path,
+                            tt->actual_name,
+                            print_in_addr_t(tt->local, 0, &gc),
+                            print_in_addr_t(tt->remote_netmask, 0, &gc)
+                            );
+            }
+            else
+            {
+                argv_printf(&argv,
+                            "%s addr del dev %s %s/%d",
+                            iproute_path,
+                            tt->actual_name,
+                            print_in_addr_t(tt->local, 0, &gc),
+                            netmask_to_netbits2(tt->remote_netmask)
+                            );
+            }
+#else  /* ifdef ENABLE_IPROUTE */
+            argv_printf(&argv,
+                        "%s %s 0.0.0.0",
+                        IFCONFIG_PATH,
+                        tt->actual_name
+                        );
+#endif /* ifdef ENABLE_IPROUTE */
+
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, NULL, 0, "Linux ip addr del failed");
+
+            if (tt->did_ifconfig_ipv6_setup)
+            {
+                const char *ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0, &gc);
+
+#ifdef ENABLE_IPROUTE
+                argv_printf(&argv, "%s -6 addr del %s/%d dev %s",
+                            iproute_path,
+                            ifconfig_ipv6_local,
+                            tt->netbits_ipv6,
+                            tt->actual_name
+                            );
+                argv_msg(M_INFO, &argv);
+                openvpn_execve_check(&argv, NULL, 0, "Linux ip -6 addr del failed");
+#else  /* ifdef ENABLE_IPROUTE */
+                argv_printf(&argv,
+                            "%s %s del %s/%d",
+                            IFCONFIG_PATH,
+                            tt->actual_name,
+                            ifconfig_ipv6_local,
+                            tt->netbits_ipv6
+                            );
+                argv_msg(M_INFO, &argv);
+                openvpn_execve_check(&argv, NULL, 0, "Linux ifconfig inet6 del failed");
+#endif
+            }
+
+            argv_reset(&argv);
+            gc_free(&gc);
+        }
+        close_tun_generic(tt);
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return write(tt->fd, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return read(tt->fd, buf, len);
+}
+
+#elif defined(TARGET_SOLARIS)
+
+#ifndef TUNNEWPPA
+#error I need the symbol TUNNEWPPA from net/if_tun.h
+#endif
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    int if_fd, ip_muxid, arp_muxid, arp_fd, ppa = -1;
+    struct lifreq ifr;
+    const char *ptr;
+    const char *ip_node, *arp_node;
+    const char *dev_tuntap_type;
+    int link_type;
+    bool is_tun;
+    struct strioctl strioc_if, strioc_ppa;
+
+    /* improved generic TUN/TAP driver from
+     * http://www.whiteboard.ne.jp/~admin2/tuntap/
+     * has IPv6 support
+     */
+    CLEAR(ifr);
+
+    if (tt->type == DEV_TYPE_NULL)
+    {
+        open_null(tt);
+        return;
+    }
+
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        ip_node = "/dev/udp";
+        if (!dev_node)
+        {
+            dev_node = "/dev/tun";
+        }
+        dev_tuntap_type = "tun";
+        link_type = I_PLINK;
+        is_tun = true;
+    }
+    else if (tt->type == DEV_TYPE_TAP)
+    {
+        ip_node = "/dev/udp";
+        if (!dev_node)
+        {
+            dev_node = "/dev/tap";
+        }
+        arp_node = dev_node;
+        dev_tuntap_type = "tap";
+        link_type = I_PLINK; /* was: I_LINK */
+        is_tun = false;
+    }
+    else
+    {
+        msg(M_FATAL, "I don't recognize device %s as a tun or tap device",
+            dev);
+    }
+
+    if ((tt->ip_fd = open(ip_node, O_RDWR, 0)) < 0)
+    {
+        msg(M_ERR, "Can't open %s", ip_node);
+    }
+
+    if ((tt->fd = open(dev_node, O_RDWR, 0)) < 0)
+    {
+        msg(M_ERR, "Can't open %s", dev_node);
+    }
+
+    /* get unit number */
+    if (*dev)
+    {
+        ptr = dev;
+        while (*ptr && !isdigit((int) *ptr))
+        {
+            ptr++;
+        }
+        ppa = atoi(ptr);
+    }
+
+    /* Assign a new PPA and get its unit number. */
+    strioc_ppa.ic_cmd = TUNNEWPPA;
+    strioc_ppa.ic_timout = 0;
+    strioc_ppa.ic_len = sizeof(ppa);
+    strioc_ppa.ic_dp = (char *)&ppa;
+
+    if (*ptr == '\0')           /* no number given, try dynamic */
+    {
+        bool found_one = false;
+        while (!found_one && ppa < 64)
+        {
+            int new_ppa = ioctl(tt->fd, I_STR, &strioc_ppa);
+            if (new_ppa >= 0)
+            {
+                msg( M_INFO, "open_tun: got dynamic interface '%s%d'", dev_tuntap_type, new_ppa );
+                ppa = new_ppa;
+                found_one = true;
+                break;
+            }
+            if (errno != EEXIST)
+            {
+                msg(M_ERR, "open_tun: unexpected error trying to find free %s interface", dev_tuntap_type );
+            }
+            ppa++;
+        }
+        if (!found_one)
+        {
+            msg(M_ERR, "open_tun: could not find free %s interface, give up.", dev_tuntap_type );
+        }
+    }
+    else                        /* try this particular one */
+    {
+        if ((ppa = ioctl(tt->fd, I_STR, &strioc_ppa)) < 0)
+        {
+            msg(M_ERR, "Can't assign PPA for new interface (%s%d)", dev_tuntap_type, ppa );
+        }
+    }
+
+    if ((if_fd = open(dev_node, O_RDWR, 0)) < 0)
+    {
+        msg(M_ERR, "Can't open %s (2)", dev_node);
+    }
+
+    if (ioctl(if_fd, I_PUSH, "ip") < 0)
+    {
+        msg(M_ERR, "Can't push IP module");
+    }
+
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        /* Assign ppa according to the unit number returned by tun device */
+        if (ioctl(if_fd, IF_UNITSEL, (char *) &ppa) < 0)
+        {
+            msg(M_ERR, "Can't set PPA %d", ppa);
+        }
+    }
+
+    tt->actual_name = (char *) malloc(32);
+    check_malloc_return(tt->actual_name);
+
+    openvpn_snprintf(tt->actual_name, 32, "%s%d", dev_tuntap_type, ppa);
+
+    if (tt->type == DEV_TYPE_TAP)
+    {
+        if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) < 0)
+        {
+            msg(M_ERR, "Can't get flags\n");
+        }
+        strncpynt(ifr.lifr_name, tt->actual_name, sizeof(ifr.lifr_name));
+        ifr.lifr_ppa = ppa;
+        /* Assign ppa according to the unit number returned by tun device */
+        if (ioctl(if_fd, SIOCSLIFNAME, &ifr) < 0)
+        {
+            msg(M_ERR, "Can't set PPA %d", ppa);
+        }
+        if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) <0)
+        {
+            msg(M_ERR, "Can't get flags\n");
+        }
+        /* Push arp module to if_fd */
+        if (ioctl(if_fd, I_PUSH, "arp") < 0)
+        {
+            msg(M_ERR, "Can't push ARP module");
+        }
+
+        /* Pop any modules on the stream */
+        while (true)
+        {
+            if (ioctl(tt->ip_fd, I_POP, NULL) < 0)
+            {
+                break;
+            }
+        }
+        /* Push arp module to ip_fd */
+        if (ioctl(tt->ip_fd, I_PUSH, "arp") < 0)
+        {
+            msg(M_ERR, "Can't push ARP module\n");
+        }
+
+        /* Open arp_fd */
+        if ((arp_fd = open(arp_node, O_RDWR, 0)) < 0)
+        {
+            msg(M_ERR, "Can't open %s\n", arp_node);
+        }
+        /* Push arp module to arp_fd */
+        if (ioctl(arp_fd, I_PUSH, "arp") < 0)
+        {
+            msg(M_ERR, "Can't push ARP module\n");
+        }
+
+        /* Set ifname to arp */
+        strioc_if.ic_cmd = SIOCSLIFNAME;
+        strioc_if.ic_timout = 0;
+        strioc_if.ic_len = sizeof(ifr);
+        strioc_if.ic_dp = (char *)&ifr;
+        if (ioctl(arp_fd, I_STR, &strioc_if) < 0)
+        {
+            msg(M_ERR, "Can't set ifname to arp\n");
+        }
+    }
+
+    if ((ip_muxid = ioctl(tt->ip_fd, link_type, if_fd)) < 0)
+    {
+        msg(M_ERR, "Can't link %s device to IP", dev_tuntap_type);
+    }
+
+    if (tt->type == DEV_TYPE_TAP)
+    {
+        if ((arp_muxid = ioctl(tt->ip_fd, link_type, arp_fd)) < 0)
+        {
+            msg(M_ERR, "Can't link %s device to ARP", dev_tuntap_type);
+        }
+        close(arp_fd);
+    }
+
+    CLEAR(ifr);
+    strncpynt(ifr.lifr_name, tt->actual_name, sizeof(ifr.lifr_name));
+    ifr.lifr_ip_muxid  = ip_muxid;
+    if (tt->type == DEV_TYPE_TAP)
+    {
+        ifr.lifr_arp_muxid = arp_muxid;
+    }
+
+    if (ioctl(tt->ip_fd, SIOCSLIFMUXID, &ifr) < 0)
+    {
+        if (tt->type == DEV_TYPE_TAP)
+        {
+            ioctl(tt->ip_fd, I_PUNLINK, arp_muxid);
+        }
+        ioctl(tt->ip_fd, I_PUNLINK, ip_muxid);
+        msg(M_ERR, "Can't set multiplexor id");
+    }
+
+    set_nonblock(tt->fd);
+    set_cloexec(tt->fd);
+    set_cloexec(tt->ip_fd);
+
+    msg(M_INFO, "TUN/TAP device %s opened", tt->actual_name);
+}
+
+static void
+solaris_close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        /* IPv6 interfaces need to be 'manually' de-configured */
+        if (tt->did_ifconfig_ipv6_setup)
+        {
+            struct argv argv = argv_new();
+            argv_printf( &argv, "%s %s inet6 unplumb",
+                         IFCONFIG_PATH, tt->actual_name );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, NULL, 0, "Solaris ifconfig inet6 unplumb failed");
+            argv_reset(&argv);
+        }
+
+        if (tt->ip_fd >= 0)
+        {
+            struct lifreq ifr;
+            CLEAR(ifr);
+            strncpynt(ifr.lifr_name, tt->actual_name, sizeof(ifr.lifr_name));
+
+            if (ioctl(tt->ip_fd, SIOCGLIFFLAGS, &ifr) < 0)
+            {
+                msg(M_WARN | M_ERRNO, "Can't get iface flags");
+            }
+
+            if (ioctl(tt->ip_fd, SIOCGLIFMUXID, &ifr) < 0)
+            {
+                msg(M_WARN | M_ERRNO, "Can't get multiplexor id");
+            }
+
+            if (tt->type == DEV_TYPE_TAP)
+            {
+                if (ioctl(tt->ip_fd, I_PUNLINK, ifr.lifr_arp_muxid) < 0)
+                {
+                    msg(M_WARN | M_ERRNO, "Can't unlink interface(arp)");
+                }
+            }
+
+            if (ioctl(tt->ip_fd, I_PUNLINK, ifr.lifr_ip_muxid) < 0)
+            {
+                msg(M_WARN | M_ERRNO, "Can't unlink interface(ip)");
+            }
+
+            close(tt->ip_fd);
+            tt->ip_fd = -1;
+        }
+
+        if (tt->fd >= 0)
+        {
+            close(tt->fd);
+            tt->fd = -1;
+        }
+    }
+}
+
+/*
+ * Close TUN device.
+ */
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        solaris_close_tun(tt);
+
+        if (tt->actual_name)
+        {
+            free(tt->actual_name);
+        }
+
+        clear_tuntap(tt);
+        free(tt);
+    }
+}
+
+static void
+solaris_error_close(struct tuntap *tt, const struct env_set *es,
+                    const char *actual, bool unplumb_inet6 )
+{
+    struct argv argv = argv_new();
+
+    if (unplumb_inet6)
+    {
+        argv_printf( &argv, "%s %s inet6 unplumb",
+                     IFCONFIG_PATH, actual );
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, es, 0, "Solaris ifconfig inet6 unplumb failed");
+    }
+
+    argv_printf(&argv,
+                "%s %s unplumb",
+                IFCONFIG_PATH,
+                actual);
+
+    argv_msg(M_INFO, &argv);
+    openvpn_execve_check(&argv, es, 0, "Solaris ifconfig unplumb failed");
+    close_tun(tt);
+    msg(M_FATAL, "Solaris ifconfig failed");
+    argv_reset(&argv);
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    struct strbuf sbuf;
+    sbuf.len = len;
+    sbuf.buf = (char *)buf;
+    return putmsg(tt->fd, NULL, &sbuf, 0) >= 0 ? sbuf.len : -1;
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    struct strbuf sbuf;
+    int f = 0;
+
+    sbuf.maxlen = len;
+    sbuf.buf = (char *)buf;
+    return getmsg(tt->fd, NULL, &sbuf, &f) >= 0 ? sbuf.len : -1;
+}
+
+#elif defined(TARGET_OPENBSD)
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    open_tun_generic(dev, dev_type, dev_node, true, tt);
+
+    /* Enable multicast on the interface */
+    if (tt->fd >= 0)
+    {
+        struct tuninfo info;
+
+        if (ioctl(tt->fd, TUNGIFINFO, &info) < 0)
+        {
+            msg(M_WARN | M_ERRNO, "Can't get interface info");
+        }
+
+#ifdef IFF_MULTICAST /* openbsd 4.x doesn't have this */
+        info.flags |= IFF_MULTICAST;
+#endif
+
+        if (ioctl(tt->fd, TUNSIFINFO, &info) < 0)
+        {
+            msg(M_WARN | M_ERRNO, "Can't set interface info");
+        }
+    }
+}
+
+/* tun(4): "If the device was created by opening /dev/tunN, it will be
+ *          automatically destroyed.  Devices created via ifconfig(8) are
+ *          only marked as not running and traffic will be dropped
+ *          returning EHOSTDOWN."
+ * --> no special handling should be needed - *but* OpenBSD is misbehaving
+ * here: if the interface was put in tap mode ("ifconfig tunN link0"), it
+ * *will* stay around, and needs to be cleaned up manually
+ */
+
+void
+close_tun(struct tuntap *tt)
+{
+    /* only *TAP* devices need destroying, tun devices auto-self-destruct
+     */
+    if (tt && (tt->type == DEV_TYPE_TUN || tt->persistent_if ) )
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+    else if (tt)
+    {
+        struct gc_arena gc = gc_new();
+        struct argv argv = argv_new();
+
+        /* setup command, close tun dev (clears tt->actual_name!), run command
+         */
+
+        argv_printf(&argv, "%s %s destroy",
+                    IFCONFIG_PATH, tt->actual_name);
+
+        close_tun_generic(tt);
+
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, NULL, 0, "OpenBSD 'destroy tun interface' failed (non-critical)");
+
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return write_tun_header(tt, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return read_tun_header(tt, buf, len);
+}
+
+#elif defined(TARGET_NETBSD)
+
+/*
+ * NetBSD before 4.0 does not support IPv6 on tun out of the box,
+ * but there exists a patch (sys/net/if_tun.c, 1.79->1.80, see PR 32944).
+ *
+ * NetBSD 4.0 and up do, but we need to put the tun interface into
+ * "multi_af" mode, which will prepend the address family to all packets
+ * (same as OpenBSD and FreeBSD).  If this is not enabled, the kernel
+ * silently drops all IPv6 packets on output and gets confused on input.
+ *
+ * On earlier versions, multi_af is not available at all, so we have
+ * two different NetBSD code variants here :-(
+ *
+ */
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    open_tun_generic(dev, dev_type, dev_node, true, tt);
+
+    if (tt->fd >= 0)
+    {
+        int i = IFF_POINTOPOINT|IFF_MULTICAST;
+        ioctl(tt->fd, TUNSIFMODE, &i);   /* multicast on */
+        i = 0;
+        ioctl(tt->fd, TUNSLMODE, &i);    /* link layer mode off */
+
+        if (tt->type == DEV_TYPE_TUN)
+        {
+            i = 1;
+            if (ioctl(tt->fd, TUNSIFHEAD, &i) < 0)      /* multi-af mode on */
+            {
+                msg(M_WARN | M_ERRNO, "ioctl(TUNSIFHEAD)");
+            }
+        }
+    }
+}
+
+/* the current way OpenVPN handles tun devices on NetBSD leads to
+ * lingering tunX interfaces after close -> for a full cleanup, they
+ * need to be explicitely destroyed
+ */
+void
+close_tun(struct tuntap *tt)
+{
+    /* only tun devices need destroying, tap devices auto-self-destruct
+     */
+    if (tt && ( tt->type != DEV_TYPE_TUN || tt->persistent_if ) )
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+    else if (tt)
+    {
+        struct gc_arena gc = gc_new();
+        struct argv argv = argv_new();
+
+        /* setup command, close tun dev (clears tt->actual_name!), run command
+         */
+
+        argv_printf(&argv, "%s %s destroy",
+                    IFCONFIG_PATH, tt->actual_name);
+
+        close_tun_generic(tt);
+
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, NULL, 0, "NetBSD 'destroy tun interface' failed (non-critical)");
+
+        free(tt);
+    }
+}
+
+static inline int
+netbsd_modify_read_write_return(int len)
+{
+    if (len > 0)
+    {
+        return len > sizeof(u_int32_t) ? len - sizeof(u_int32_t) : 0;
+    }
+    else
+    {
+        return len;
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+        struct openvpn_iphdr *iph;
+
+        iph = (struct openvpn_iphdr *) buf;
+
+        if (OPENVPN_IPH_GET_VER(iph->version_len) == 6)
+        {
+            type = htonl(AF_INET6);
+        }
+        else
+        {
+            type = htonl(AF_INET);
+        }
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return netbsd_modify_read_write_return(writev(tt->fd, iv, 2));
+    }
+    else
+    {
+        return write(tt->fd, buf, len);
+    }
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return netbsd_modify_read_write_return(readv(tt->fd, iv, 2));
+    }
+    else
+    {
+        return read(tt->fd, buf, len);
+    }
+}
+
+#elif defined(TARGET_FREEBSD)
+
+static inline int
+freebsd_modify_read_write_return(int len)
+{
+    if (len > 0)
+    {
+        return len > sizeof(u_int32_t) ? len - sizeof(u_int32_t) : 0;
+    }
+    else
+    {
+        return len;
+    }
+}
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    open_tun_generic(dev, dev_type, dev_node, true, tt);
+
+    if (tt->fd >= 0 && tt->type == DEV_TYPE_TUN)
+    {
+        int i = IFF_POINTOPOINT | IFF_MULTICAST;
+
+        if (ioctl(tt->fd, TUNSIFMODE, &i) < 0)
+        {
+            msg(M_WARN | M_ERRNO, "ioctl(TUNSIFMODE)");
+        }
+        i = 1;
+        if (ioctl(tt->fd, TUNSIFHEAD, &i) < 0)
+        {
+            msg(M_WARN | M_ERRNO, "ioctl(TUNSIFHEAD)");
+        }
+    }
+}
+
+/* tun(4): "These network interfaces persist until the if_tun.ko module is
+ *          unloaded, or until removed with the ifconfig(8) command."
+ *          (verified for FreeBSD 6.3, 7.4, 8.2 and 9, same for tap(4))
+ *
+ * so, to avoid lingering tun/tap interfaces after OpenVPN quits,
+ * we need to call "ifconfig ... destroy" for cleanup
+ */
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt && tt->persistent_if)        /* keep pre-existing if around */
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+    else if (tt)                        /* close and destroy */
+    {
+        struct argv argv = argv_new();
+
+        /* setup command, close tun dev (clears tt->actual_name!), run command
+         */
+
+        argv_printf(&argv, "%s %s destroy",
+                    IFCONFIG_PATH, tt->actual_name);
+
+        close_tun_generic(tt);
+
+        argv_msg(M_INFO, &argv);
+        openvpn_execve_check(&argv, NULL, 0, "FreeBSD 'destroy tun interface' failed (non-critical)");
+
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+        struct ip *iph;
+
+        iph = (struct ip *) buf;
+
+        if (iph->ip_v == 6)
+        {
+            type = htonl(AF_INET6);
+        }
+        else
+        {
+            type = htonl(AF_INET);
+        }
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return freebsd_modify_read_write_return(writev(tt->fd, iv, 2));
+    }
+    else
+    {
+        return write(tt->fd, buf, len);
+    }
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return freebsd_modify_read_write_return(readv(tt->fd, iv, 2));
+    }
+    else
+    {
+        return read(tt->fd, buf, len);
+    }
+}
+
+#elif defined(TARGET_DRAGONFLY)
+
+static inline int
+dragonfly_modify_read_write_return(int len)
+{
+    if (len > 0)
+    {
+        return len > sizeof(u_int32_t) ? len - sizeof(u_int32_t) : 0;
+    }
+    else
+    {
+        return len;
+    }
+}
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    open_tun_generic(dev, dev_type, dev_node, true, tt);
+
+    if (tt->fd >= 0)
+    {
+        int i = 0;
+
+        /* Disable extended modes */
+        ioctl(tt->fd, TUNSLMODE, &i);
+        i = 1;
+        ioctl(tt->fd, TUNSIFHEAD, &i);
+    }
+}
+
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+        struct ip *iph;
+
+        iph = (struct ip *) buf;
+
+        if (iph->ip_v == 6)
+        {
+            type = htonl(AF_INET6);
+        }
+        else
+        {
+            type = htonl(AF_INET);
+        }
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return dragonfly_modify_read_write_return(writev(tt->fd, iv, 2));
+    }
+    else
+    {
+        return write(tt->fd, buf, len);
+    }
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        u_int32_t type;
+        struct iovec iv[2];
+
+        iv[0].iov_base = (char *)&type;
+        iv[0].iov_len = sizeof(type);
+        iv[1].iov_base = buf;
+        iv[1].iov_len = len;
+
+        return dragonfly_modify_read_write_return(readv(tt->fd, iv, 2));
+    }
+    else
+    {
+        return read(tt->fd, buf, len);
+    }
+}
+
+#elif defined(TARGET_DARWIN)
+
+/* Darwin (MacOS X) is mostly "just use the generic stuff", but there
+ * is always one caveat...:
+ *
+ * If IPv6 is configured, and the tun device is closed, the IPv6 address
+ * configured to the tun interface changes to a lingering /128 route
+ * pointing to lo0.  Need to unconfigure...  (observed on 10.5)
+ */
+
+/*
+ * utun is the native Darwin tun driver present since at least 10.7
+ * Thanks goes to Jonathan Levin for providing an example how to utun
+ * (http://newosxbook.com/src.jl?tree=listings&file=17-15-utun.c)
+ */
+
+#ifdef HAVE_NET_IF_UTUN_H
+
+/* Helper functions that tries to open utun device
+ * return -2 on early initialization failures (utun not supported
+ * at all (old OS X) and -1 on initlization failure of utun
+ * device (utun works but utunX is already used */
+static
+int
+utun_open_helper(struct ctl_info ctlInfo, int utunnum)
+{
+    struct sockaddr_ctl sc;
+    int fd;
+
+    fd = socket(PF_SYSTEM, SOCK_DGRAM, SYSPROTO_CONTROL);
+
+    if (fd < 0)
+    {
+        msg(M_INFO | M_ERRNO, "Opening utun (socket(SYSPROTO_CONTROL))");
+        return -2;
+    }
+
+    if (ioctl(fd, CTLIOCGINFO, &ctlInfo) == -1)
+    {
+        close(fd);
+        msg(M_INFO | M_ERRNO, "Opening utun (ioctl(CTLIOCGINFO))");
+        return -2;
+    }
+
+
+    sc.sc_id = ctlInfo.ctl_id;
+    sc.sc_len = sizeof(sc);
+    sc.sc_family = AF_SYSTEM;
+    sc.ss_sysaddr = AF_SYS_CONTROL;
+
+    sc.sc_unit = utunnum+1;
+
+
+    /* If the connect is successful, a utun%d device will be created, where "%d"
+     * is (sc.sc_unit - 1) */
+
+    if (connect(fd, (struct sockaddr *)&sc, sizeof(sc)) < 0)
+    {
+        msg(M_INFO | M_ERRNO, "Opening utun (connect(AF_SYS_CONTROL))");
+        close(fd);
+        return -1;
+    }
+
+    set_nonblock(fd);
+    set_cloexec(fd); /* don't pass fd to scripts */
+
+    return fd;
+}
+
+void
+open_darwin_utun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    struct ctl_info ctlInfo;
+    int fd;
+    char utunname[20];
+    int utunnum = -1;
+    socklen_t utunname_len = sizeof(utunname);
+
+    /* dev_node is simply utun, do the normal dynamic utun
+     * otherwise try to parse the utun number */
+    if (dev_node && (strcmp("utun", dev_node) != 0 ))
+    {
+        if (sscanf(dev_node, "utun%d", &utunnum) != 1)
+        {
+            msg(M_FATAL, "Cannot parse 'dev-node %s' please use 'dev-node utunX'"
+                "to use a utun device number X", dev_node);
+        }
+    }
+
+
+
+    CLEAR(ctlInfo);
+    if (strlcpy(ctlInfo.ctl_name, UTUN_CONTROL_NAME, sizeof(ctlInfo.ctl_name)) >=
+        sizeof(ctlInfo.ctl_name))
+    {
+        msg(M_ERR, "Opening utun: UTUN_CONTROL_NAME too long");
+    }
+
+    /* try to open first available utun device if no specific utun is requested */
+    if (utunnum == -1)
+    {
+        for (utunnum = 0; utunnum<255; utunnum++)
+        {
+            fd = utun_open_helper(ctlInfo, utunnum);
+            /* Break if the fd is valid,
+             * or if early initalization failed (-2) */
+            if (fd !=-1)
+            {
+                break;
+            }
+        }
+    }
+    else
+    {
+        fd = utun_open_helper(ctlInfo, utunnum);
+    }
+
+    /* opening an utun device failed */
+    tt->fd = fd;
+
+    if (fd < 0)
+    {
+        return;
+    }
+
+    /* Retrieve the assigned interface name. */
+    if (getsockopt(fd, SYSPROTO_CONTROL, UTUN_OPT_IFNAME, utunname, &utunname_len))
+    {
+        msg(M_ERR | M_ERRNO, "Error retrieving utun interface name");
+    }
+
+    tt->actual_name = string_alloc(utunname, NULL);
+
+    msg(M_INFO, "Opened utun device %s", utunname);
+    tt->is_utun = true;
+}
+
+#endif /* ifdef HAVE_NET_IF_UTUN_H */
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+#ifdef HAVE_NET_IF_UTUN_H
+    /* If dev_node does not start start with utun assume regular tun/tap */
+    if ((!dev_node && tt->type==DEV_TYPE_TUN)
+        || (dev_node && !strncmp(dev_node, "utun", 4)))
+    {
+
+        /* Check if user has specific dev_type tap and forced utun with
+         * dev-node utun */
+        if (tt->type!=DEV_TYPE_TUN)
+        {
+            msg(M_FATAL, "Cannot use utun devices with --dev-type %s",
+                dev_type_string(dev, dev_type));
+        }
+
+        /* Try utun first and fall back to normal tun if utun fails
+         * and dev_node is not specified */
+        open_darwin_utun(dev, dev_type, dev_node, tt);
+
+        if (!tt->is_utun)
+        {
+            if (!dev_node)
+            {
+                /* No explicit utun and utun failed, try the generic way) */
+                msg(M_INFO, "Failed to open utun device. Falling back to /dev/tun device");
+                open_tun_generic(dev, dev_type, NULL, true, tt);
+            }
+            else
+            {
+                /* Specific utun device or generic utun request with no tun
+                 * fall back failed, consider this a fatal failure */
+                msg(M_FATAL, "Cannot open utun device");
+            }
+        }
+    }
+    else
+#endif /* ifdef HAVE_NET_IF_UTUN_H */
+    {
+
+        /* Use plain dev-node tun to select /dev/tun style
+         * Unset dev_node variable prior to passing to open_tun_generic to
+         * let open_tun_generic pick the first available tun device */
+
+        if (dev_node && strcmp(dev_node, "tun")==0)
+        {
+            dev_node = NULL;
+        }
+
+        open_tun_generic(dev, dev_type, dev_node, true, tt);
+    }
+}
+
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        struct gc_arena gc = gc_new();
+        struct argv argv = argv_new();
+
+        if (tt->did_ifconfig_ipv6_setup)
+        {
+            const char *ifconfig_ipv6_local =
+                print_in6_addr(tt->local_ipv6, 0, &gc);
+
+            argv_printf(&argv, "%s delete -inet6 %s",
+                        ROUTE_PATH, ifconfig_ipv6_local );
+            argv_msg(M_INFO, &argv);
+            openvpn_execve_check(&argv, NULL, 0, "MacOS X 'remove inet6 route' failed (non-critical)");
+        }
+
+        close_tun_generic(tt);
+        free(tt);
+        argv_reset(&argv);
+        gc_free(&gc);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+#ifdef HAVE_NET_IF_UTUN_H
+    if (tt->is_utun)
+    {
+        return write_tun_header(tt, buf, len);
+    }
+    else
+#endif
+    return write(tt->fd, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+#ifdef HAVE_NET_IF_UTUN_H
+    if (tt->is_utun)
+    {
+        return read_tun_header(tt, buf, len);
+    }
+    else
+#endif
+    return read(tt->fd, buf, len);
+}
+
+#elif defined(TARGET_AIX)
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    char tunname[256];
+    char dynamic_name[20];
+    const char *p;
+
+    if (tt->type == DEV_TYPE_NULL)
+    {
+        open_null(tt);
+        return;
+    }
+
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        msg(M_FATAL, "no support for 'tun' devices on AIX" );
+    }
+
+    if (strncmp( dev, "tap", 3 ) != 0 || dev_node)
+    {
+        msg(M_FATAL, "'--dev %s' and/or '--dev-node' not supported on AIX, use '--dev tap0', 'tap1', etc.", dev );
+    }
+
+    if (strcmp( dev, "tap" ) == 0)              /* find first free tap dev */
+    {                                           /* (= no /dev/tapN node) */
+        int i;
+        for (i = 0; i<99; i++)
+        {
+            openvpn_snprintf(tunname, sizeof(tunname), "/dev/tap%d", i);
+            if (access( tunname, F_OK ) < 0 && errno == ENOENT)
+            {
+                break;
+            }
+        }
+        if (i >= 99)
+        {
+            msg( M_FATAL, "cannot find unused tap device" );
+        }
+
+        openvpn_snprintf( dynamic_name, sizeof(dynamic_name), "tap%d", i );
+        dev = dynamic_name;
+    }
+    else                                        /* name given, sanity check */
+    {
+        /* ensure that dev name is "tap+<digits>" *only* */
+        p = &dev[3];
+        while (isdigit(*p) )
+        {
+            p++;
+        }
+        if (*p != '\0')
+        {
+            msg( M_FATAL, "TAP device name must be '--dev tapNNNN'" );
+        }
+
+        openvpn_snprintf(tunname, sizeof(tunname), "/dev/%s", dev);
+    }
+
+    /* pre-existing device?
+     */
+    if (access( tunname, F_OK ) < 0 && errno == ENOENT)
+    {
+
+        /* tunnel device must be created with 'ifconfig tapN create'
+         */
+        struct argv argv = argv_new();
+        struct env_set *es = env_set_create(NULL);
+        argv_printf(&argv, "%s %s create", IFCONFIG_PATH, dev);
+        argv_msg(M_INFO, &argv);
+        env_set_add( es, "ODMDIR=/etc/objrepos" );
+        openvpn_execve_check(&argv, es, S_FATAL, "AIX 'create tun interface' failed");
+        env_set_destroy(es);
+    }
+    else
+    {
+        /* we didn't make it, we're not going to break it */
+        tt->persistent_if = TRUE;
+    }
+
+    if ((tt->fd = open(tunname, O_RDWR)) < 0)
+    {
+        msg(M_ERR, "Cannot open TAP device '%s'", tunname);
+    }
+
+    set_nonblock(tt->fd);
+    set_cloexec(tt->fd); /* don't pass fd to scripts */
+    msg(M_INFO, "TUN/TAP device %s opened", tunname);
+
+    /* tt->actual_name is passed to up and down scripts and used as the ifconfig dev name */
+    tt->actual_name = string_alloc(dev, NULL);
+}
+
+/* tap devices need to be manually destroyed on AIX
+ */
+void
+close_tun(struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+    struct env_set *es = env_set_create(NULL);
+
+    if (!tt)
+    {
+        return;
+    }
+
+    /* persistent devices need IP address unconfig, others need destroyal
+     */
+    if (tt->persistent_if)
+    {
+        argv_printf(&argv, "%s %s 0.0.0.0 down",
+                    IFCONFIG_PATH, tt->actual_name);
+    }
+    else
+    {
+        argv_printf(&argv, "%s %s destroy",
+                    IFCONFIG_PATH, tt->actual_name);
+    }
+
+    close_tun_generic(tt);
+    argv_msg(M_INFO, &argv);
+    env_set_add( es, "ODMDIR=/etc/objrepos" );
+    openvpn_execve_check(&argv, es, 0, "AIX 'destroy tap interface' failed (non-critical)");
+
+    free(tt);
+    env_set_destroy(es);
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return write(tt->fd, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return read(tt->fd, buf, len);
+}
+
+#elif defined(_WIN32)
+
+int
+tun_read_queue(struct tuntap *tt, int maxsize)
+{
+    if (tt->reads.iostate == IOSTATE_INITIAL)
+    {
+        DWORD len;
+        BOOL status;
+        int err;
+
+        /* reset buf to its initial state */
+        tt->reads.buf = tt->reads.buf_init;
+
+        len = maxsize ? maxsize : BLEN(&tt->reads.buf);
+        ASSERT(len <= BLEN(&tt->reads.buf));
+
+        /* the overlapped read will signal this event on I/O completion */
+        ASSERT(ResetEvent(tt->reads.overlapped.hEvent));
+
+        status = ReadFile(
+            tt->hand,
+            BPTR(&tt->reads.buf),
+            len,
+            &tt->reads.size,
+            &tt->reads.overlapped
+            );
+
+        if (status) /* operation completed immediately? */
+        {
+            /* since we got an immediate return, we must signal the event object ourselves */
+            ASSERT(SetEvent(tt->reads.overlapped.hEvent));
+
+            tt->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+            tt->reads.status = 0;
+
+            dmsg(D_WIN32_IO, "WIN32 I/O: TAP Read immediate return [%d,%d]",
+                 (int) len,
+                 (int) tt->reads.size);
+        }
+        else
+        {
+            err = GetLastError();
+            if (err == ERROR_IO_PENDING) /* operation queued? */
+            {
+                tt->reads.iostate = IOSTATE_QUEUED;
+                tt->reads.status = err;
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Read queued [%d]",
+                     (int) len);
+            }
+            else /* error occurred */
+            {
+                struct gc_arena gc = gc_new();
+                ASSERT(SetEvent(tt->reads.overlapped.hEvent));
+                tt->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+                tt->reads.status = err;
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Read error [%d] : %s",
+                     (int) len,
+                     strerror_win32(status, &gc));
+                gc_free(&gc);
+            }
+        }
+    }
+    return tt->reads.iostate;
+}
+
+int
+tun_write_queue(struct tuntap *tt, struct buffer *buf)
+{
+    if (tt->writes.iostate == IOSTATE_INITIAL)
+    {
+        BOOL status;
+        int err;
+
+        /* make a private copy of buf */
+        tt->writes.buf = tt->writes.buf_init;
+        tt->writes.buf.len = 0;
+        ASSERT(buf_copy(&tt->writes.buf, buf));
+
+        /* the overlapped write will signal this event on I/O completion */
+        ASSERT(ResetEvent(tt->writes.overlapped.hEvent));
+
+        status = WriteFile(
+            tt->hand,
+            BPTR(&tt->writes.buf),
+            BLEN(&tt->writes.buf),
+            &tt->writes.size,
+            &tt->writes.overlapped
+            );
+
+        if (status) /* operation completed immediately? */
+        {
+            tt->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+
+            /* since we got an immediate return, we must signal the event object ourselves */
+            ASSERT(SetEvent(tt->writes.overlapped.hEvent));
+
+            tt->writes.status = 0;
+
+            dmsg(D_WIN32_IO, "WIN32 I/O: TAP Write immediate return [%d,%d]",
+                 BLEN(&tt->writes.buf),
+                 (int) tt->writes.size);
+        }
+        else
+        {
+            err = GetLastError();
+            if (err == ERROR_IO_PENDING) /* operation queued? */
+            {
+                tt->writes.iostate = IOSTATE_QUEUED;
+                tt->writes.status = err;
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Write queued [%d]",
+                     BLEN(&tt->writes.buf));
+            }
+            else /* error occurred */
+            {
+                struct gc_arena gc = gc_new();
+                ASSERT(SetEvent(tt->writes.overlapped.hEvent));
+                tt->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+                tt->writes.status = err;
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Write error [%d] : %s",
+                     BLEN(&tt->writes.buf),
+                     strerror_win32(err, &gc));
+                gc_free(&gc);
+            }
+        }
+    }
+    return tt->writes.iostate;
+}
+
+int
+tun_finalize(
+    HANDLE h,
+    struct overlapped_io *io,
+    struct buffer *buf)
+{
+    int ret = -1;
+    BOOL status;
+
+    switch (io->iostate)
+    {
+        case IOSTATE_QUEUED:
+            status = GetOverlappedResult(
+                h,
+                &io->overlapped,
+                &io->size,
+                FALSE
+                );
+            if (status)
+            {
+                /* successful return for a queued operation */
+                if (buf)
+                {
+                    *buf = io->buf;
+                }
+                ret = io->size;
+                io->iostate = IOSTATE_INITIAL;
+                ASSERT(ResetEvent(io->overlapped.hEvent));
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Completion success [%d]", ret);
+            }
+            else
+            {
+                /* error during a queued operation */
+                ret = -1;
+                if (GetLastError() != ERROR_IO_INCOMPLETE)
+                {
+                    /* if no error (i.e. just not finished yet),
+                     * then DON'T execute this code */
+                    io->iostate = IOSTATE_INITIAL;
+                    ASSERT(ResetEvent(io->overlapped.hEvent));
+                    msg(D_WIN32_IO | M_ERRNO, "WIN32 I/O: TAP Completion error");
+                }
+            }
+            break;
+
+        case IOSTATE_IMMEDIATE_RETURN:
+            io->iostate = IOSTATE_INITIAL;
+            ASSERT(ResetEvent(io->overlapped.hEvent));
+            if (io->status)
+            {
+                /* error return for a non-queued operation */
+                SetLastError(io->status);
+                ret = -1;
+                msg(D_WIN32_IO | M_ERRNO, "WIN32 I/O: TAP Completion non-queued error");
+            }
+            else
+            {
+                /* successful return for a non-queued operation */
+                if (buf)
+                {
+                    *buf = io->buf;
+                }
+                ret = io->size;
+                dmsg(D_WIN32_IO, "WIN32 I/O: TAP Completion non-queued success [%d]", ret);
+            }
+            break;
+
+        case IOSTATE_INITIAL: /* were we called without proper queueing? */
+            SetLastError(ERROR_INVALID_FUNCTION);
+            ret = -1;
+            dmsg(D_WIN32_IO, "WIN32 I/O: TAP Completion BAD STATE");
+            break;
+
+        default:
+            ASSERT(0);
+    }
+
+    if (buf)
+    {
+        buf->len = ret;
+    }
+    return ret;
+}
+
+const struct tap_reg *
+get_tap_reg(struct gc_arena *gc)
+{
+    HKEY adapter_key;
+    LONG status;
+    DWORD len;
+    struct tap_reg *first = NULL;
+    struct tap_reg *last = NULL;
+    int i = 0;
+
+    status = RegOpenKeyEx(
+        HKEY_LOCAL_MACHINE,
+        ADAPTER_KEY,
+        0,
+        KEY_READ,
+        &adapter_key);
+
+    if (status != ERROR_SUCCESS)
+    {
+        msg(M_FATAL, "Error opening registry key: %s", ADAPTER_KEY);
+    }
+
+    while (true)
+    {
+        char enum_name[256];
+        char unit_string[256];
+        HKEY unit_key;
+        char component_id_string[] = "ComponentId";
+        char component_id[256];
+        char net_cfg_instance_id_string[] = "NetCfgInstanceId";
+        char net_cfg_instance_id[256];
+        DWORD data_type;
+
+        len = sizeof(enum_name);
+        status = RegEnumKeyEx(
+            adapter_key,
+            i,
+            enum_name,
+            &len,
+            NULL,
+            NULL,
+            NULL,
+            NULL);
+        if (status == ERROR_NO_MORE_ITEMS)
+        {
+            break;
+        }
+        else if (status != ERROR_SUCCESS)
+        {
+            msg(M_FATAL, "Error enumerating registry subkeys of key: %s",
+                ADAPTER_KEY);
+        }
+
+        openvpn_snprintf(unit_string, sizeof(unit_string), "%s\\%s",
+                         ADAPTER_KEY, enum_name);
+
+        status = RegOpenKeyEx(
+            HKEY_LOCAL_MACHINE,
+            unit_string,
+            0,
+            KEY_READ,
+            &unit_key);
+
+        if (status != ERROR_SUCCESS)
+        {
+            dmsg(D_REGISTRY, "Error opening registry key: %s", unit_string);
+        }
+        else
+        {
+            len = sizeof(component_id);
+            status = RegQueryValueEx(
+                unit_key,
+                component_id_string,
+                NULL,
+                &data_type,
+                component_id,
+                &len);
+
+            if (status != ERROR_SUCCESS || data_type != REG_SZ)
+            {
+                dmsg(D_REGISTRY, "Error opening registry key: %s\\%s",
+                     unit_string, component_id_string);
+            }
+            else
+            {
+                len = sizeof(net_cfg_instance_id);
+                status = RegQueryValueEx(
+                    unit_key,
+                    net_cfg_instance_id_string,
+                    NULL,
+                    &data_type,
+                    net_cfg_instance_id,
+                    &len);
+
+                if (status == ERROR_SUCCESS && data_type == REG_SZ)
+                {
+                    if (!strcmp(component_id, TAP_WIN_COMPONENT_ID) ||
+                        !strcmp(component_id, "root\\" TAP_WIN_COMPONENT_ID))
+                    {
+                        struct tap_reg *reg;
+                        ALLOC_OBJ_CLEAR_GC(reg, struct tap_reg, gc);
+                        reg->guid = string_alloc(net_cfg_instance_id, gc);
+
+                        /* link into return list */
+                        if (!first)
+                        {
+                            first = reg;
+                        }
+                        if (last)
+                        {
+                            last->next = reg;
+                        }
+                        last = reg;
+                    }
+                }
+            }
+            RegCloseKey(unit_key);
+        }
+        ++i;
+    }
+
+    RegCloseKey(adapter_key);
+    return first;
+}
+
+const struct panel_reg *
+get_panel_reg(struct gc_arena *gc)
+{
+    LONG status;
+    HKEY network_connections_key;
+    DWORD len;
+    struct panel_reg *first = NULL;
+    struct panel_reg *last = NULL;
+    int i = 0;
+
+    status = RegOpenKeyEx(
+        HKEY_LOCAL_MACHINE,
+        NETWORK_CONNECTIONS_KEY,
+        0,
+        KEY_READ,
+        &network_connections_key);
+
+    if (status != ERROR_SUCCESS)
+    {
+        msg(M_FATAL, "Error opening registry key: %s", NETWORK_CONNECTIONS_KEY);
+    }
+
+    while (true)
+    {
+        char enum_name[256];
+        char connection_string[256];
+        HKEY connection_key;
+        WCHAR name_data[256];
+        DWORD name_type;
+        const WCHAR name_string[] = L"Name";
+
+        len = sizeof(enum_name);
+        status = RegEnumKeyEx(
+            network_connections_key,
+            i,
+            enum_name,
+            &len,
+            NULL,
+            NULL,
+            NULL,
+            NULL);
+        if (status == ERROR_NO_MORE_ITEMS)
+        {
+            break;
+        }
+        else if (status != ERROR_SUCCESS)
+        {
+            msg(M_FATAL, "Error enumerating registry subkeys of key: %s",
+                NETWORK_CONNECTIONS_KEY);
+        }
+
+        openvpn_snprintf(connection_string, sizeof(connection_string),
+                         "%s\\%s\\Connection",
+                         NETWORK_CONNECTIONS_KEY, enum_name);
+
+        status = RegOpenKeyEx(
+            HKEY_LOCAL_MACHINE,
+            connection_string,
+            0,
+            KEY_READ,
+            &connection_key);
+
+        if (status != ERROR_SUCCESS)
+        {
+            dmsg(D_REGISTRY, "Error opening registry key: %s", connection_string);
+        }
+        else
+        {
+            len = sizeof(name_data);
+            status = RegQueryValueExW(
+                connection_key,
+                name_string,
+                NULL,
+                &name_type,
+                (LPBYTE) name_data,
+                &len);
+
+            if (status != ERROR_SUCCESS || name_type != REG_SZ)
+            {
+                dmsg(D_REGISTRY, "Error opening registry key: %s\\%s\\%ls",
+                     NETWORK_CONNECTIONS_KEY, connection_string, name_string);
+            }
+            else
+            {
+                int n;
+                LPSTR name;
+                struct panel_reg *reg;
+
+                ALLOC_OBJ_CLEAR_GC(reg, struct panel_reg, gc);
+                n = WideCharToMultiByte(CP_UTF8, 0, name_data, -1, NULL, 0, NULL, NULL);
+                name = gc_malloc(n, false, gc);
+                WideCharToMultiByte(CP_UTF8, 0, name_data, -1, name, n, NULL, NULL);
+                reg->name = name;
+                reg->guid = string_alloc(enum_name, gc);
+
+                /* link into return list */
+                if (!first)
+                {
+                    first = reg;
+                }
+                if (last)
+                {
+                    last->next = reg;
+                }
+                last = reg;
+            }
+            RegCloseKey(connection_key);
+        }
+        ++i;
+    }
+
+    RegCloseKey(network_connections_key);
+
+    return first;
+}
+
+/*
+ * Check that two addresses are part of the same 255.255.255.252 subnet.
+ */
+void
+verify_255_255_255_252(in_addr_t local, in_addr_t remote)
+{
+    struct gc_arena gc = gc_new();
+    const unsigned int mask = 3;
+    const char *err = NULL;
+
+    if (local == remote)
+    {
+        err = "must be different";
+        goto error;
+    }
+    if ((local & (~mask)) != (remote & (~mask)))
+    {
+        err = "must exist within the same 255.255.255.252 subnet.  This is a limitation of --dev tun when used with the TAP-WIN32 driver";
+        goto error;
+    }
+    if ((local & mask) == 0
+        || (local & mask) == 3
+        || (remote & mask) == 0
+        || (remote & mask) == 3)
+    {
+        err = "cannot use the first or last address within a given 255.255.255.252 subnet.  This is a limitation of --dev tun when used with the TAP-WIN32 driver";
+        goto error;
+    }
+
+    gc_free(&gc);
+    return;
+
+error:
+    msg(M_FATAL, "There is a problem in your selection of --ifconfig endpoints [local=%s, remote=%s].  The local and remote VPN endpoints %s.  Try '" PACKAGE " --show-valid-subnets' option for more info.",
+        print_in_addr_t(local, 0, &gc),
+        print_in_addr_t(remote, 0, &gc),
+        err);
+    gc_free(&gc);
+}
+
+void
+show_valid_win32_tun_subnets(void)
+{
+    int i;
+    int col = 0;
+
+    printf("On Windows, point-to-point IP support (i.e. --dev tun)\n");
+    printf("is emulated by the TAP-Windows driver.  The major limitation\n");
+    printf("imposed by this approach is that the --ifconfig local and\n");
+    printf("remote endpoints must be part of the same 255.255.255.252\n");
+    printf("subnet.  The following list shows examples of endpoint\n");
+    printf("pairs which satisfy this requirement.  Only the final\n");
+    printf("component of the IP address pairs is at issue.\n\n");
+    printf("As an example, the following option would be correct:\n");
+    printf("    --ifconfig 10.7.0.5 10.7.0.6 (on host A)\n");
+    printf("    --ifconfig 10.7.0.6 10.7.0.5 (on host B)\n");
+    printf("because [5,6] is part of the below list.\n\n");
+
+    for (i = 0; i < 256; i += 4)
+    {
+        printf("[%3d,%3d] ", i+1, i+2);
+        if (++col > 4)
+        {
+            col = 0;
+            printf("\n");
+        }
+    }
+    if (col)
+    {
+        printf("\n");
+    }
+}
+
+void
+show_tap_win_adapters(int msglev, int warnlev)
+{
+    struct gc_arena gc = gc_new();
+
+    bool warn_panel_null = false;
+    bool warn_panel_dup = false;
+    bool warn_tap_dup = false;
+
+    int links;
+
+    const struct tap_reg *tr;
+    const struct tap_reg *tr1;
+    const struct panel_reg *pr;
+
+    const struct tap_reg *tap_reg = get_tap_reg(&gc);
+    const struct panel_reg *panel_reg = get_panel_reg(&gc);
+
+    msg(msglev, "Available TAP-WIN32 adapters [name, GUID]:");
+
+    /* loop through each TAP-Windows adapter registry entry */
+    for (tr = tap_reg; tr != NULL; tr = tr->next)
+    {
+        links = 0;
+
+        /* loop through each network connections entry in the control panel */
+        for (pr = panel_reg; pr != NULL; pr = pr->next)
+        {
+            if (!strcmp(tr->guid, pr->guid))
+            {
+                msg(msglev, "'%s' %s", pr->name, tr->guid);
+                ++links;
+            }
+        }
+
+        if (links > 1)
+        {
+            warn_panel_dup = true;
+        }
+        else if (links == 0)
+        {
+            /* a TAP adapter exists without a link from the network
+             * connections control panel */
+            warn_panel_null = true;
+            msg(msglev, "[NULL] %s", tr->guid);
+        }
+    }
+
+    /* check for TAP-Windows adapter duplicated GUIDs */
+    for (tr = tap_reg; tr != NULL; tr = tr->next)
+    {
+        for (tr1 = tap_reg; tr1 != NULL; tr1 = tr1->next)
+        {
+            if (tr != tr1 && !strcmp(tr->guid, tr1->guid))
+            {
+                warn_tap_dup = true;
+            }
+        }
+    }
+
+    /* warn on registry inconsistencies */
+    if (warn_tap_dup)
+    {
+        msg(warnlev, "WARNING: Some TAP-Windows adapters have duplicate GUIDs");
+    }
+
+    if (warn_panel_dup)
+    {
+        msg(warnlev, "WARNING: Some TAP-Windows adapters have duplicate links from the Network Connections control panel");
+    }
+
+    if (warn_panel_null)
+    {
+        msg(warnlev, "WARNING: Some TAP-Windows adapters have no link from the Network Connections control panel");
+    }
+
+    gc_free(&gc);
+}
+
+/*
+ * Confirm that GUID is a TAP-Windows adapter.
+ */
+static bool
+is_tap_win(const char *guid, const struct tap_reg *tap_reg)
+{
+    const struct tap_reg *tr;
+
+    for (tr = tap_reg; tr != NULL; tr = tr->next)
+    {
+        if (guid && !strcmp(tr->guid, guid))
+        {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+static const char *
+guid_to_name(const char *guid, const struct panel_reg *panel_reg)
+{
+    const struct panel_reg *pr;
+
+    for (pr = panel_reg; pr != NULL; pr = pr->next)
+    {
+        if (guid && !strcmp(pr->guid, guid))
+        {
+            return pr->name;
+        }
+    }
+
+    return NULL;
+}
+
+static const char *
+name_to_guid(const char *name, const struct tap_reg *tap_reg, const struct panel_reg *panel_reg)
+{
+    const struct panel_reg *pr;
+
+    for (pr = panel_reg; pr != NULL; pr = pr->next)
+    {
+        if (name && !strcmp(pr->name, name) && is_tap_win(pr->guid, tap_reg))
+        {
+            return pr->guid;
+        }
+    }
+
+    return NULL;
+}
+
+static void
+at_least_one_tap_win(const struct tap_reg *tap_reg)
+{
+    if (!tap_reg)
+    {
+        msg(M_FATAL, "There are no TAP-Windows adapters on this system.  You should be able to create a TAP-Windows adapter by going to Start -> All Programs -> TAP-Windows -> Utilities -> Add a new TAP-Windows virtual ethernet adapter.");
+    }
+}
+
+/*
+ * Get an adapter GUID and optional actual_name from the
+ * registry for the TAP device # = device_number.
+ */
+static const char *
+get_unspecified_device_guid(const int device_number,
+                            char *actual_name,
+                            int actual_name_size,
+                            const struct tap_reg *tap_reg_src,
+                            const struct panel_reg *panel_reg_src,
+                            struct gc_arena *gc)
+{
+    const struct tap_reg *tap_reg = tap_reg_src;
+    struct buffer ret = clear_buf();
+    struct buffer actual = clear_buf();
+    int i;
+
+    ASSERT(device_number >= 0);
+
+    /* Make sure we have at least one TAP adapter */
+    if (!tap_reg)
+    {
+        return NULL;
+    }
+
+    /* The actual_name output buffer may be NULL */
+    if (actual_name)
+    {
+        ASSERT(actual_name_size > 0);
+        buf_set_write(&actual, actual_name, actual_name_size);
+    }
+
+    /* Move on to specified device number */
+    for (i = 0; i < device_number; i++)
+    {
+        tap_reg = tap_reg->next;
+        if (!tap_reg)
+        {
+            return NULL;
+        }
+    }
+
+    /* Save Network Panel name (if exists) in actual_name */
+    if (actual_name)
+    {
+        const char *act = guid_to_name(tap_reg->guid, panel_reg_src);
+        if (act)
+        {
+            buf_printf(&actual, "%s", act);
+        }
+        else
+        {
+            buf_printf(&actual, "%s", tap_reg->guid);
+        }
+    }
+
+    /* Save GUID for return value */
+    ret = alloc_buf_gc(256, gc);
+    buf_printf(&ret, "%s", tap_reg->guid);
+    return BSTR(&ret);
+}
+
+/*
+ * Lookup a --dev-node adapter name in the registry
+ * returning the GUID and optional actual_name.
+ */
+static const char *
+get_device_guid(const char *name,
+                char *actual_name,
+                int actual_name_size,
+                const struct tap_reg *tap_reg,
+                const struct panel_reg *panel_reg,
+                struct gc_arena *gc)
+{
+    struct buffer ret = alloc_buf_gc(256, gc);
+    struct buffer actual = clear_buf();
+
+    /* Make sure we have at least one TAP adapter */
+    if (!tap_reg)
+    {
+        return NULL;
+    }
+
+    /* The actual_name output buffer may be NULL */
+    if (actual_name)
+    {
+        ASSERT(actual_name_size > 0);
+        buf_set_write(&actual, actual_name, actual_name_size);
+    }
+
+    /* Check if GUID was explicitly specified as --dev-node parameter */
+    if (is_tap_win(name, tap_reg))
+    {
+        const char *act = guid_to_name(name, panel_reg);
+        buf_printf(&ret, "%s", name);
+        if (act)
+        {
+            buf_printf(&actual, "%s", act);
+        }
+        else
+        {
+            buf_printf(&actual, "%s", name);
+        }
+        return BSTR(&ret);
+    }
+
+    /* Lookup TAP adapter in network connections list */
+    {
+        const char *guid = name_to_guid(name, tap_reg, panel_reg);
+        if (guid)
+        {
+            buf_printf(&actual, "%s", name);
+            buf_printf(&ret, "%s", guid);
+            return BSTR(&ret);
+        }
+    }
+
+    return NULL;
+}
+
+/*
+ * Get adapter info list
+ */
+const IP_ADAPTER_INFO *
+get_adapter_info_list(struct gc_arena *gc)
+{
+    ULONG size = 0;
+    IP_ADAPTER_INFO *pi = NULL;
+    DWORD status;
+
+    if ((status = GetAdaptersInfo(NULL, &size)) != ERROR_BUFFER_OVERFLOW)
+    {
+        msg(M_INFO, "GetAdaptersInfo #1 failed (status=%u) : %s",
+            (unsigned int)status,
+            strerror_win32(status, gc));
+    }
+    else
+    {
+        pi = (PIP_ADAPTER_INFO) gc_malloc(size, false, gc);
+        if ((status = GetAdaptersInfo(pi, &size)) != NO_ERROR)
+        {
+            msg(M_INFO, "GetAdaptersInfo #2 failed (status=%u) : %s",
+                (unsigned int)status,
+                strerror_win32(status, gc));
+            pi = NULL;
+        }
+    }
+    return pi;
+}
+
+const IP_PER_ADAPTER_INFO *
+get_per_adapter_info(const DWORD index, struct gc_arena *gc)
+{
+    ULONG size = 0;
+    IP_PER_ADAPTER_INFO *pi = NULL;
+    DWORD status;
+
+    if (index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        if ((status = GetPerAdapterInfo(index, NULL, &size)) != ERROR_BUFFER_OVERFLOW)
+        {
+            msg(M_INFO, "GetPerAdapterInfo #1 failed (status=%u) : %s",
+                (unsigned int)status,
+                strerror_win32(status, gc));
+        }
+        else
+        {
+            pi = (PIP_PER_ADAPTER_INFO) gc_malloc(size, false, gc);
+            if ((status = GetPerAdapterInfo((ULONG)index, pi, &size)) == ERROR_SUCCESS)
+            {
+                return pi;
+            }
+            else
+            {
+                msg(M_INFO, "GetPerAdapterInfo #2 failed (status=%u) : %s",
+                    (unsigned int)status,
+                    strerror_win32(status, gc));
+            }
+        }
+    }
+    return pi;
+}
+
+static const IP_INTERFACE_INFO *
+get_interface_info_list(struct gc_arena *gc)
+{
+    ULONG size = 0;
+    IP_INTERFACE_INFO *ii = NULL;
+    DWORD status;
+
+    if ((status = GetInterfaceInfo(NULL, &size)) != ERROR_INSUFFICIENT_BUFFER)
+    {
+        msg(M_INFO, "GetInterfaceInfo #1 failed (status=%u) : %s",
+            (unsigned int)status,
+            strerror_win32(status, gc));
+    }
+    else
+    {
+        ii = (PIP_INTERFACE_INFO) gc_malloc(size, false, gc);
+        if ((status = GetInterfaceInfo(ii, &size)) == NO_ERROR)
+        {
+            return ii;
+        }
+        else
+        {
+            msg(M_INFO, "GetInterfaceInfo #2 failed (status=%u) : %s",
+                (unsigned int)status,
+                strerror_win32(status, gc));
+        }
+    }
+    return ii;
+}
+
+static const IP_ADAPTER_INDEX_MAP *
+get_interface_info(DWORD index, struct gc_arena *gc)
+{
+    const IP_INTERFACE_INFO *list = get_interface_info_list(gc);
+    if (list)
+    {
+        int i;
+        for (i = 0; i < list->NumAdapters; ++i)
+        {
+            const IP_ADAPTER_INDEX_MAP *inter = &list->Adapter[i];
+            if (index == inter->Index)
+            {
+                return inter;
+            }
+        }
+    }
+    return NULL;
+}
+
+/*
+ * Given an adapter index, return a pointer to the
+ * IP_ADAPTER_INFO structure for that adapter.
+ */
+
+const IP_ADAPTER_INFO *
+get_adapter(const IP_ADAPTER_INFO *ai, DWORD index)
+{
+    if (ai && index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        const IP_ADAPTER_INFO *a;
+
+        /* find index in the linked list */
+        for (a = ai; a != NULL; a = a->Next)
+        {
+            if (a->Index == index)
+            {
+                return a;
+            }
+        }
+    }
+    return NULL;
+}
+
+const IP_ADAPTER_INFO *
+get_adapter_info(DWORD index, struct gc_arena *gc)
+{
+    return get_adapter(get_adapter_info_list(gc), index);
+}
+
+static int
+get_adapter_n_ip_netmask(const IP_ADAPTER_INFO *ai)
+{
+    if (ai)
+    {
+        int n = 0;
+        const IP_ADDR_STRING *ip = &ai->IpAddressList;
+
+        while (ip)
+        {
+            ++n;
+            ip = ip->Next;
+        }
+        return n;
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+static bool
+get_adapter_ip_netmask(const IP_ADAPTER_INFO *ai, const int n, in_addr_t *ip, in_addr_t *netmask)
+{
+    bool ret = false;
+    *ip = 0;
+    *netmask = 0;
+
+    if (ai)
+    {
+        const IP_ADDR_STRING *iplist = &ai->IpAddressList;
+        int i = 0;
+
+        while (iplist)
+        {
+            if (i == n)
+            {
+                break;
+            }
+            ++i;
+            iplist = iplist->Next;
+        }
+
+        if (iplist)
+        {
+            const unsigned int getaddr_flags = GETADDR_HOST_ORDER;
+            const char *ip_str = iplist->IpAddress.String;
+            const char *netmask_str = iplist->IpMask.String;
+            bool succeed1 = false;
+            bool succeed2 = false;
+
+            if (ip_str && netmask_str && strlen(ip_str) && strlen(netmask_str))
+            {
+                *ip = getaddr(getaddr_flags, ip_str, 0, &succeed1, NULL);
+                *netmask = getaddr(getaddr_flags, netmask_str, 0, &succeed2, NULL);
+                ret = (succeed1 == true && succeed2 == true);
+            }
+        }
+    }
+
+    return ret;
+}
+
+static bool
+test_adapter_ip_netmask(const IP_ADAPTER_INFO *ai, const in_addr_t ip, const in_addr_t netmask)
+{
+    if (ai)
+    {
+        in_addr_t ip_adapter = 0;
+        in_addr_t netmask_adapter = 0;
+        const bool status = get_adapter_ip_netmask(ai, 0, &ip_adapter, &netmask_adapter);
+        return (status && ip_adapter == ip && netmask_adapter == netmask);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+const IP_ADAPTER_INFO *
+get_tun_adapter(const struct tuntap *tt, const IP_ADAPTER_INFO *list)
+{
+    if (list && tt)
+    {
+        return get_adapter(list, tt->adapter_index);
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+bool
+is_adapter_up(const struct tuntap *tt, const IP_ADAPTER_INFO *list)
+{
+    int i;
+    bool ret = false;
+
+    const IP_ADAPTER_INFO *ai = get_tun_adapter(tt, list);
+
+    if (ai)
+    {
+        const int n = get_adapter_n_ip_netmask(ai);
+
+        /* loop once for every IP/netmask assigned to adapter */
+        for (i = 0; i < n; ++i)
+        {
+            in_addr_t ip, netmask;
+            if (get_adapter_ip_netmask(ai, i, &ip, &netmask))
+            {
+                if (tt->local && tt->adapter_netmask)
+                {
+                    /* wait for our --ifconfig parms to match the actual adapter parms */
+                    if (tt->local == ip && tt->adapter_netmask == netmask)
+                    {
+                        ret = true;
+                    }
+                }
+                else
+                {
+                    /* --ifconfig was not defined, maybe using a real DHCP server */
+                    if (ip && netmask)
+                    {
+                        ret = true;
+                    }
+                }
+            }
+        }
+    }
+    else
+    {
+        ret = true; /* this can occur when TAP adapter is bridged */
+
+    }
+    return ret;
+}
+
+bool
+is_ip_in_adapter_subnet(const IP_ADAPTER_INFO *ai, const in_addr_t ip, in_addr_t *highest_netmask)
+{
+    int i;
+    bool ret = false;
+
+    if (highest_netmask)
+    {
+        *highest_netmask = 0;
+    }
+
+    if (ai)
+    {
+        const int n = get_adapter_n_ip_netmask(ai);
+        for (i = 0; i < n; ++i)
+        {
+            in_addr_t adapter_ip, adapter_netmask;
+            if (get_adapter_ip_netmask(ai, i, &adapter_ip, &adapter_netmask))
+            {
+                if (adapter_ip && adapter_netmask && (ip & adapter_netmask) == (adapter_ip & adapter_netmask))
+                {
+                    if (highest_netmask && adapter_netmask > *highest_netmask)
+                    {
+                        *highest_netmask = adapter_netmask;
+                    }
+                    ret = true;
+                }
+            }
+        }
+    }
+    return ret;
+}
+
+DWORD
+adapter_index_of_ip(const IP_ADAPTER_INFO *list,
+                    const in_addr_t ip,
+                    int *count,
+                    in_addr_t *netmask)
+{
+    struct gc_arena gc = gc_new();
+    DWORD ret = TUN_ADAPTER_INDEX_INVALID;
+    in_addr_t highest_netmask = 0;
+    int lowest_metric = INT_MAX;
+    bool first = true;
+
+    if (count)
+    {
+        *count = 0;
+    }
+
+    while (list)
+    {
+        in_addr_t hn;
+
+        if (is_ip_in_adapter_subnet(list, ip, &hn))
+        {
+            int metric = get_interface_metric(list->Index, AF_INET, NULL);
+            if (first || hn > highest_netmask)
+            {
+                highest_netmask = hn;
+                if (metric >= 0)
+                {
+                    lowest_metric = metric;
+                }
+                if (count)
+                {
+                    *count = 1;
+                }
+                ret = list->Index;
+                first = false;
+            }
+            else if (hn == highest_netmask)
+            {
+                if (count)
+                {
+                    ++*count;
+                }
+                if (metric >= 0 && metric < lowest_metric)
+                {
+                    ret = list->Index;
+                    lowest_metric = metric;
+                }
+            }
+        }
+        list = list->Next;
+    }
+
+    dmsg(D_ROUTE_DEBUG, "DEBUG: IP Locate: ip=%s nm=%s index=%d count=%d metric=%d",
+         print_in_addr_t(ip, 0, &gc),
+         print_in_addr_t(highest_netmask, 0, &gc),
+         (int)ret,
+         count ? *count : -1,
+         lowest_metric);
+
+    if (ret == TUN_ADAPTER_INDEX_INVALID && count)
+    {
+        *count = 0;
+    }
+
+    if (netmask)
+    {
+        *netmask = highest_netmask;
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Given an adapter index, return true if the adapter
+ * is DHCP disabled.
+ */
+
+#define DHCP_STATUS_UNDEF     0
+#define DHCP_STATUS_ENABLED   1
+#define DHCP_STATUS_DISABLED  2
+
+static int
+dhcp_status(DWORD index)
+{
+    struct gc_arena gc = gc_new();
+    int ret = DHCP_STATUS_UNDEF;
+    if (index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        const IP_ADAPTER_INFO *ai = get_adapter_info(index, &gc);
+
+        if (ai)
+        {
+            if (ai->DhcpEnabled)
+            {
+                ret = DHCP_STATUS_ENABLED;
+            }
+            else
+            {
+                ret = DHCP_STATUS_DISABLED;
+            }
+        }
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Delete all temporary address/netmask pairs which were added
+ * to adapter (given by index) by previous calls to AddIPAddress.
+ */
+static void
+delete_temp_addresses(DWORD index)
+{
+    struct gc_arena gc = gc_new();
+    const IP_ADAPTER_INFO *a = get_adapter_info(index, &gc);
+
+    if (a)
+    {
+        const IP_ADDR_STRING *ip = &a->IpAddressList;
+        while (ip)
+        {
+            DWORD status;
+            const DWORD context = ip->Context;
+
+            if ((status = DeleteIPAddress((ULONG) context)) == NO_ERROR)
+            {
+                msg(M_INFO, "Successfully deleted previously set dynamic IP/netmask: %s/%s",
+                    ip->IpAddress.String,
+                    ip->IpMask.String);
+            }
+            else
+            {
+                const char *empty = "0.0.0.0";
+                if (strcmp(ip->IpAddress.String, empty)
+                    || strcmp(ip->IpMask.String, empty))
+                {
+                    msg(M_INFO, "NOTE: could not delete previously set dynamic IP/netmask: %s/%s (status=%u)",
+                        ip->IpAddress.String,
+                        ip->IpMask.String,
+                        (unsigned int)status);
+                }
+            }
+            ip = ip->Next;
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Get interface index for use with IP Helper API functions.
+ */
+static DWORD
+get_adapter_index_method_1(const char *guid)
+{
+    DWORD index;
+    ULONG aindex;
+    wchar_t wbuf[256];
+    swprintf(wbuf, SIZE(wbuf), L"\\DEVICE\\TCPIP_%S", guid);
+    wbuf [SIZE(wbuf) - 1] = 0;
+    if (GetAdapterIndex(wbuf, &aindex) != NO_ERROR)
+    {
+        index = TUN_ADAPTER_INDEX_INVALID;
+    }
+    else
+    {
+        index = (DWORD)aindex;
+    }
+    return index;
+}
+
+static DWORD
+get_adapter_index_method_2(const char *guid)
+{
+    struct gc_arena gc = gc_new();
+    DWORD index = TUN_ADAPTER_INDEX_INVALID;
+
+    const IP_ADAPTER_INFO *list = get_adapter_info_list(&gc);
+
+    while (list)
+    {
+        if (!strcmp(guid, list->AdapterName))
+        {
+            index = list->Index;
+            break;
+        }
+        list = list->Next;
+    }
+
+    gc_free(&gc);
+    return index;
+}
+
+static DWORD
+get_adapter_index(const char *guid)
+{
+    DWORD index;
+    index = get_adapter_index_method_1(guid);
+    if (index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        index = get_adapter_index_method_2(guid);
+    }
+    if (index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        msg(M_INFO, "NOTE: could not get adapter index for %s", guid);
+    }
+    return index;
+}
+
+static DWORD
+get_adapter_index_flexible(const char *name)  /* actual name or GUID */
+{
+    struct gc_arena gc = gc_new();
+    DWORD index;
+    index = get_adapter_index_method_1(name);
+    if (index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        index = get_adapter_index_method_2(name);
+    }
+    if (index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        const struct tap_reg *tap_reg = get_tap_reg(&gc);
+        const struct panel_reg *panel_reg = get_panel_reg(&gc);
+        const char *guid = name_to_guid(name, tap_reg, panel_reg);
+        index = get_adapter_index_method_1(guid);
+        if (index == TUN_ADAPTER_INDEX_INVALID)
+        {
+            index = get_adapter_index_method_2(guid);
+        }
+    }
+    if (index == TUN_ADAPTER_INDEX_INVALID)
+    {
+        msg(M_INFO, "NOTE: could not get adapter index for name/GUID '%s'", name);
+    }
+    gc_free(&gc);
+    return index;
+}
+
+/*
+ * Return a string representing a PIP_ADDR_STRING
+ */
+static const char *
+format_ip_addr_string(const IP_ADDR_STRING *ip, struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    while (ip)
+    {
+        buf_printf(&out, "%s", ip->IpAddress.String);
+        if (strlen(ip->IpMask.String))
+        {
+            buf_printf(&out, "/");
+            buf_printf(&out, "%s", ip->IpMask.String);
+        }
+        buf_printf(&out, " ");
+        ip = ip->Next;
+    }
+    return BSTR(&out);
+}
+
+/*
+ * Show info for a single adapter
+ */
+static void
+show_adapter(int msglev, const IP_ADAPTER_INFO *a, struct gc_arena *gc)
+{
+    msg(msglev, "%s", a->Description);
+    msg(msglev, "  Index = %d", (int)a->Index);
+    msg(msglev, "  GUID = %s", a->AdapterName);
+    msg(msglev, "  IP = %s", format_ip_addr_string(&a->IpAddressList, gc));
+    msg(msglev, "  MAC = %s", format_hex_ex(a->Address, a->AddressLength, 0, 1, ":", gc));
+    msg(msglev, "  GATEWAY = %s", format_ip_addr_string(&a->GatewayList, gc));
+    if (a->DhcpEnabled)
+    {
+        msg(msglev, "  DHCP SERV = %s", format_ip_addr_string(&a->DhcpServer, gc));
+        msg(msglev, "  DHCP LEASE OBTAINED = %s", time_string(a->LeaseObtained, 0, false, gc));
+        msg(msglev, "  DHCP LEASE EXPIRES  = %s", time_string(a->LeaseExpires, 0, false, gc));
+    }
+    if (a->HaveWins)
+    {
+        msg(msglev, "  PRI WINS = %s", format_ip_addr_string(&a->PrimaryWinsServer, gc));
+        msg(msglev, "  SEC WINS = %s", format_ip_addr_string(&a->SecondaryWinsServer, gc));
+    }
+
+    {
+        const IP_PER_ADAPTER_INFO *pai = get_per_adapter_info(a->Index, gc);
+        if (pai)
+        {
+            msg(msglev, "  DNS SERV = %s", format_ip_addr_string(&pai->DnsServerList, gc));
+        }
+    }
+}
+
+/*
+ * Show current adapter list
+ */
+void
+show_adapters(int msglev)
+{
+    struct gc_arena gc = gc_new();
+    const IP_ADAPTER_INFO *ai = get_adapter_info_list(&gc);
+
+    msg(msglev, "SYSTEM ADAPTER LIST");
+    if (ai)
+    {
+        const IP_ADAPTER_INFO *a;
+
+        /* find index in the linked list */
+        for (a = ai; a != NULL; a = a->Next)
+        {
+            show_adapter(msglev, a, &gc);
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Set a particular TAP-Windows adapter (or all of them if
+ * adapter_name == NULL) to allow it to be opened from
+ * a non-admin account.  This setting will only persist
+ * for the lifetime of the device object.
+ */
+
+static void
+tap_allow_nonadmin_access_handle(const char *device_path, HANDLE hand)
+{
+    struct security_attributes sa;
+    BOOL status;
+
+    if (!init_security_attributes_allow_all(&sa))
+    {
+        msg(M_ERR, "Error: init SA failed");
+    }
+
+    status = SetKernelObjectSecurity(hand, DACL_SECURITY_INFORMATION, &sa.sd);
+    if (!status)
+    {
+        msg(M_ERRNO, "Error: SetKernelObjectSecurity failed on %s", device_path);
+    }
+    else
+    {
+        msg(M_INFO|M_NOPREFIX, "TAP-Windows device: %s [Non-admin access allowed]", device_path);
+    }
+}
+
+void
+tap_allow_nonadmin_access(const char *dev_node)
+{
+    struct gc_arena gc = gc_new();
+    const struct tap_reg *tap_reg = get_tap_reg(&gc);
+    const struct panel_reg *panel_reg = get_panel_reg(&gc);
+    const char *device_guid = NULL;
+    HANDLE hand;
+    char actual_buffer[256];
+    char device_path[256];
+
+    at_least_one_tap_win(tap_reg);
+
+    if (dev_node)
+    {
+        /* Get the device GUID for the device specified with --dev-node. */
+        device_guid = get_device_guid(dev_node, actual_buffer, sizeof(actual_buffer), tap_reg, panel_reg, &gc);
+
+        if (!device_guid)
+        {
+            msg(M_FATAL, "TAP-Windows adapter '%s' not found", dev_node);
+        }
+
+        /* Open Windows TAP-Windows adapter */
+        openvpn_snprintf(device_path, sizeof(device_path), "%s%s%s",
+                         USERMODEDEVICEDIR,
+                         device_guid,
+                         TAP_WIN_SUFFIX);
+
+        hand = CreateFile(
+            device_path,
+            MAXIMUM_ALLOWED,
+            0,              /* was: FILE_SHARE_READ */
+            0,
+            OPEN_EXISTING,
+            FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
+            0
+            );
+
+        if (hand == INVALID_HANDLE_VALUE)
+        {
+            msg(M_ERR, "CreateFile failed on TAP device: %s", device_path);
+        }
+
+        tap_allow_nonadmin_access_handle(device_path, hand);
+        CloseHandle(hand);
+    }
+    else
+    {
+        int device_number = 0;
+
+        /* Try opening all TAP devices */
+        while (true)
+        {
+            device_guid = get_unspecified_device_guid(device_number,
+                                                      actual_buffer,
+                                                      sizeof(actual_buffer),
+                                                      tap_reg,
+                                                      panel_reg,
+                                                      &gc);
+
+            if (!device_guid)
+            {
+                break;
+            }
+
+            /* Open Windows TAP-Windows adapter */
+            openvpn_snprintf(device_path, sizeof(device_path), "%s%s%s",
+                             USERMODEDEVICEDIR,
+                             device_guid,
+                             TAP_WIN_SUFFIX);
+
+            hand = CreateFile(
+                device_path,
+                MAXIMUM_ALLOWED,
+                0,              /* was: FILE_SHARE_READ */
+                0,
+                OPEN_EXISTING,
+                FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
+                0
+                );
+
+            if (hand == INVALID_HANDLE_VALUE)
+            {
+                msg(M_WARN, "CreateFile failed on TAP device: %s", device_path);
+            }
+            else
+            {
+                tap_allow_nonadmin_access_handle(device_path, hand);
+                CloseHandle(hand);
+            }
+
+            device_number++;
+        }
+    }
+    gc_free(&gc);
+}
+
+/*
+ * DHCP release/renewal
+ */
+bool
+dhcp_release_by_adapter_index(const DWORD adapter_index)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+    const IP_ADAPTER_INDEX_MAP *inter = get_interface_info(adapter_index, &gc);
+
+    if (inter)
+    {
+        DWORD status = IpReleaseAddress((IP_ADAPTER_INDEX_MAP *)inter);
+        if (status == NO_ERROR)
+        {
+            msg(D_TUNTAP_INFO, "TAP: DHCP address released");
+            ret = true;
+        }
+        else
+        {
+            msg(M_WARN, "NOTE: Release of DHCP-assigned IP address lease on TAP-Windows adapter failed: %s (code=%u)",
+                strerror_win32(status, &gc),
+                (unsigned int)status);
+        }
+    }
+
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+dhcp_release(const struct tuntap *tt)
+{
+    if (tt && tt->options.ip_win32_type == IPW32_SET_DHCP_MASQ && tt->adapter_index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        return dhcp_release_by_adapter_index(tt->adapter_index);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+bool
+dhcp_renew_by_adapter_index(const DWORD adapter_index)
+{
+    struct gc_arena gc = gc_new();
+    bool ret = false;
+    const IP_ADAPTER_INDEX_MAP *inter = get_interface_info(adapter_index, &gc);
+
+    if (inter)
+    {
+        DWORD status = IpRenewAddress((IP_ADAPTER_INDEX_MAP *)inter);
+        if (status == NO_ERROR)
+        {
+            msg(D_TUNTAP_INFO, "TAP: DHCP address renewal succeeded");
+            ret = true;
+        }
+        else
+        {
+            msg(M_WARN, "WARNING: Failed to renew DHCP IP address lease on TAP-Windows adapter: %s (code=%u)",
+                strerror_win32(status, &gc),
+                (unsigned int)status);
+        }
+    }
+    gc_free(&gc);
+    return ret;
+}
+
+static bool
+dhcp_renew(const struct tuntap *tt)
+{
+    if (tt && tt->options.ip_win32_type == IPW32_SET_DHCP_MASQ && tt->adapter_index != TUN_ADAPTER_INDEX_INVALID)
+    {
+        return dhcp_renew_by_adapter_index(tt->adapter_index);
+    }
+    else
+    {
+        return false;
+    }
+}
+
+/*
+ * netsh functions
+ */
+
+static void
+netsh_command(const struct argv *a, int n, int msglevel)
+{
+    int i;
+    for (i = 0; i < n; ++i)
+    {
+        bool status;
+        management_sleep(1);
+        netcmd_semaphore_lock();
+        argv_msg_prefix(M_INFO, a, "NETSH");
+        status = openvpn_execve_check(a, NULL, 0, "ERROR: netsh command failed");
+        netcmd_semaphore_release();
+        if (status)
+        {
+            return;
+        }
+        management_sleep(4);
+    }
+    msg(msglevel, "NETSH: command failed");
+}
+
+void
+ipconfig_register_dns(const struct env_set *es)
+{
+    struct argv argv = argv_new();
+    const char err[] = "ERROR: Windows ipconfig command failed";
+
+    msg(D_TUNTAP_INFO, "Start ipconfig commands for register-dns...");
+    netcmd_semaphore_lock();
+
+    argv_printf(&argv, "%s%sc /flushdns",
+                get_win_sys_path(),
+                WIN_IPCONFIG_PATH_SUFFIX);
+    argv_msg(D_TUNTAP_INFO, &argv);
+    openvpn_execve_check(&argv, es, 0, err);
+    argv_reset(&argv);
+
+    argv_printf(&argv, "%s%sc /registerdns",
+                get_win_sys_path(),
+                WIN_IPCONFIG_PATH_SUFFIX);
+    argv_msg(D_TUNTAP_INFO, &argv);
+    openvpn_execve_check(&argv, es, 0, err);
+    argv_reset(&argv);
+
+    netcmd_semaphore_release();
+    msg(D_TUNTAP_INFO, "End ipconfig commands for register-dns...");
+}
+
+void
+ip_addr_string_to_array(in_addr_t *dest, int *dest_len, const IP_ADDR_STRING *src)
+{
+    int i = 0;
+    while (src)
+    {
+        const unsigned int getaddr_flags = GETADDR_HOST_ORDER;
+        const char *ip_str = src->IpAddress.String;
+        in_addr_t ip = 0;
+        bool succeed = false;
+
+        if (i >= *dest_len)
+        {
+            break;
+        }
+        if (!ip_str || !strlen(ip_str))
+        {
+            break;
+        }
+
+        ip = getaddr(getaddr_flags, ip_str, 0, &succeed, NULL);
+        if (!succeed)
+        {
+            break;
+        }
+        dest[i++] = ip;
+
+        src = src->Next;
+    }
+    *dest_len = i;
+
+#if 0
+    {
+        struct gc_arena gc = gc_new();
+        msg(M_INFO, "ip_addr_string_to_array [%d]", *dest_len);
+        for (i = 0; i < *dest_len; ++i)
+        {
+            msg(M_INFO, "%s", print_in_addr_t(dest[i], 0, &gc));
+        }
+        gc_free(&gc);
+    }
+#endif
+}
+
+static bool
+ip_addr_one_to_one(const in_addr_t *a1, const int a1len, const IP_ADDR_STRING *ias)
+{
+    in_addr_t a2[8];
+    int a2len = SIZE(a2);
+    int i;
+
+    ip_addr_string_to_array(a2, &a2len, ias);
+    /*msg (M_INFO, "a1len=%d a2len=%d", a1len, a2len);*/
+    if (a1len != a2len)
+    {
+        return false;
+    }
+
+    for (i = 0; i < a1len; ++i)
+    {
+        if (a1[i] != a2[i])
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+static bool
+ip_addr_member_of(const in_addr_t addr, const IP_ADDR_STRING *ias)
+{
+    in_addr_t aa[8];
+    int len = SIZE(aa);
+    int i;
+
+    ip_addr_string_to_array(aa, &len, ias);
+    for (i = 0; i < len; ++i)
+    {
+        if (addr == aa[i])
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+/**
+ * Set the ipv6 dns servers on the specified interface.
+ * The list of dns servers currently set on the interface
+ * are cleared first.
+ * No action is taken if number of addresses (addr_len) < 1.
+ */
+static void
+netsh_set_dns6_servers(const struct in6_addr *addr_list,
+                       const int addr_len,
+                       const char *flex_name)
+{
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+
+    for (int i = 0; i < addr_len; ++i)
+    {
+        const char *fmt = (i == 0) ?
+                          "%s%sc interface ipv6 set dns %s static %s"
+                          : "%s%sc interface ipv6 add dns %s %s";
+        argv_printf(&argv, fmt, get_win_sys_path(),
+                    NETSH_PATH_SUFFIX, flex_name,
+                    print_in6_addr(addr_list[i], 0, &gc));
+
+        /* disable slow address validation on Windows 7 and higher */
+        if (win32_version_info() >= WIN_7)
+        {
+            argv_printf_cat(&argv, "%s", "validate=no");
+        }
+
+        /* Treat errors while adding as non-fatal as we do not check for duplicates */
+        netsh_command(&argv, 1, (i==0) ? M_FATAL : M_NONFATAL);
+    }
+
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+static void
+netsh_ifconfig_options(const char *type,
+                       const in_addr_t *addr_list,
+                       const int addr_len,
+                       const IP_ADDR_STRING *current,
+                       const char *flex_name,
+                       const bool test_first)
+{
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+    bool delete_first = false;
+
+    /* first check if we should delete existing DNS/WINS settings from TAP interface */
+    if (test_first)
+    {
+        if (!ip_addr_one_to_one(addr_list, addr_len, current))
+        {
+            delete_first = true;
+        }
+    }
+    else
+    {
+        delete_first = true;
+    }
+
+    /* delete existing DNS/WINS settings from TAP interface */
+    if (delete_first)
+    {
+        argv_printf(&argv, "%s%sc interface ip delete %s %s all",
+                    get_win_sys_path(),
+                    NETSH_PATH_SUFFIX,
+                    type,
+                    flex_name);
+        netsh_command(&argv, 2, M_FATAL);
+    }
+
+    /* add new DNS/WINS settings to TAP interface */
+    {
+        int count = 0;
+        int i;
+        for (i = 0; i < addr_len; ++i)
+        {
+            if (delete_first || !test_first || !ip_addr_member_of(addr_list[i], current))
+            {
+                const char *fmt = count ?
+                                  "%s%sc interface ip add %s %s %s"
+                                  : "%s%sc interface ip set %s %s static %s";
+
+                argv_printf(&argv, fmt,
+                            get_win_sys_path(),
+                            NETSH_PATH_SUFFIX,
+                            type,
+                            flex_name,
+                            print_in_addr_t(addr_list[i], 0, &gc));
+                netsh_command(&argv, 2, M_FATAL);
+
+                ++count;
+            }
+            else
+            {
+                msg(M_INFO, "NETSH: \"%s\" %s %s [already set]",
+                    flex_name,
+                    type,
+                    print_in_addr_t(addr_list[i], 0, &gc));
+            }
+        }
+    }
+
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+static void
+init_ip_addr_string2(IP_ADDR_STRING *dest, const IP_ADDR_STRING *src1, const IP_ADDR_STRING *src2)
+{
+    CLEAR(dest[0]);
+    CLEAR(dest[1]);
+    if (src1)
+    {
+        dest[0] = *src1;
+        dest[0].Next = NULL;
+    }
+    if (src2)
+    {
+        dest[1] = *src2;
+        dest[0].Next = &dest[1];
+        dest[1].Next = NULL;
+    }
+}
+
+static void
+netsh_ifconfig(const struct tuntap_options *to,
+               const char *flex_name,
+               const in_addr_t ip,
+               const in_addr_t netmask,
+               const unsigned int flags)
+{
+    struct gc_arena gc = gc_new();
+    struct argv argv = argv_new();
+    const IP_ADAPTER_INFO *ai = NULL;
+    const IP_PER_ADAPTER_INFO *pai = NULL;
+
+    if (flags & NI_TEST_FIRST)
+    {
+        const IP_ADAPTER_INFO *list = get_adapter_info_list(&gc);
+        const int index = get_adapter_index_flexible(flex_name);
+        ai = get_adapter(list, index);
+        pai = get_per_adapter_info(index, &gc);
+    }
+
+    if (flags & NI_IP_NETMASK)
+    {
+        if (test_adapter_ip_netmask(ai, ip, netmask))
+        {
+            msg(M_INFO, "NETSH: \"%s\" %s/%s [already set]",
+                flex_name,
+                print_in_addr_t(ip, 0, &gc),
+                print_in_addr_t(netmask, 0, &gc));
+        }
+        else
+        {
+            /* example: netsh interface ip set address my-tap static 10.3.0.1 255.255.255.0 */
+            argv_printf(&argv, "%s%sc interface ip set address %s static %s %s",
+                        get_win_sys_path(),
+                        NETSH_PATH_SUFFIX,
+                        flex_name,
+                        print_in_addr_t(ip, 0, &gc),
+                        print_in_addr_t(netmask, 0, &gc));
+
+            netsh_command(&argv, 4, M_FATAL);
+        }
+    }
+
+    /* set WINS/DNS options */
+    if (flags & NI_OPTIONS)
+    {
+        IP_ADDR_STRING wins[2];
+        CLEAR(wins[0]);
+        CLEAR(wins[1]);
+
+        netsh_ifconfig_options("dns",
+                               to->dns,
+                               to->dns_len,
+                               pai ? &pai->DnsServerList : NULL,
+                               flex_name,
+                               BOOL_CAST(flags & NI_TEST_FIRST));
+        if (ai && ai->HaveWins)
+        {
+            init_ip_addr_string2(wins, &ai->PrimaryWinsServer, &ai->SecondaryWinsServer);
+        }
+
+        netsh_ifconfig_options("wins",
+                               to->wins,
+                               to->wins_len,
+                               ai ? wins : NULL,
+                               flex_name,
+                               BOOL_CAST(flags & NI_TEST_FIRST));
+    }
+
+    argv_reset(&argv);
+    gc_free(&gc);
+}
+
+static void
+netsh_enable_dhcp(const char *actual_name)
+{
+    struct argv argv = argv_new();
+
+    /* example: netsh interface ip set address my-tap dhcp */
+    argv_printf(&argv,
+                "%s%sc interface ip set address %s dhcp",
+                get_win_sys_path(),
+                NETSH_PATH_SUFFIX,
+                actual_name);
+
+    netsh_command(&argv, 4, M_FATAL);
+
+    argv_reset(&argv);
+}
+
+/* Enable dhcp on tap adapter using iservice */
+static bool
+service_enable_dhcp(const struct tuntap *tt)
+{
+    DWORD len;
+    bool ret = false;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+    HANDLE pipe = tt->options.msg_channel;
+
+    enable_dhcp_message_t dhcp = {
+        .header = {
+            msg_enable_dhcp,
+            sizeof(enable_dhcp_message_t),
+            0
+        },
+        .iface = { .index = tt->adapter_index, .name = "" }
+    };
+
+    if (!WriteFile(pipe, &dhcp, sizeof(dhcp), &len, NULL)
+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "Enable_dhcp: could not talk to service: %s [%lu]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+        goto out;
+    }
+
+    if (ack.error_number != NO_ERROR)
+    {
+        msg(M_NONFATAL, "TUN: enabling dhcp using service failed: %s [status=%u if_index=%d]",
+            strerror_win32(ack.error_number, &gc), ack.error_number, dhcp.iface.index);
+    }
+    else
+    {
+        msg(M_INFO, "DHCP enabled on interface %d using service", dhcp.iface.index);
+        ret = true;
+    }
+
+out:
+    gc_free(&gc);
+    return ret;
+}
+
+/*
+ * Return a TAP name for netsh commands.
+ */
+static const char *
+netsh_get_id(const char *dev_node, struct gc_arena *gc)
+{
+    const struct tap_reg *tap_reg = get_tap_reg(gc);
+    const struct panel_reg *panel_reg = get_panel_reg(gc);
+    struct buffer actual = alloc_buf_gc(256, gc);
+    const char *guid;
+
+    at_least_one_tap_win(tap_reg);
+
+    if (dev_node)
+    {
+        guid = get_device_guid(dev_node, BPTR(&actual), BCAP(&actual), tap_reg, panel_reg, gc);
+    }
+    else
+    {
+        guid = get_unspecified_device_guid(0, BPTR(&actual), BCAP(&actual), tap_reg, panel_reg, gc);
+
+        if (get_unspecified_device_guid(1, NULL, 0, tap_reg, panel_reg, gc)) /* ambiguous if more than one TAP-Windows adapter */
+        {
+            guid = NULL;
+        }
+    }
+
+    if (!guid)
+    {
+        return "NULL";     /* not found */
+    }
+    else if (strcmp(BPTR(&actual), "NULL"))
+    {
+        return BPTR(&actual); /* control panel name */
+    }
+    else
+    {
+        return guid;       /* no control panel name, return GUID instead */
+    }
+}
+
+/*
+ * Called iteratively on TAP-Windows wait-for-initialization polling loop
+ */
+void
+tun_standby_init(struct tuntap *tt)
+{
+    tt->standby_iter = 0;
+}
+
+bool
+tun_standby(struct tuntap *tt)
+{
+    bool ret = true;
+    ++tt->standby_iter;
+    if (tt->options.ip_win32_type == IPW32_SET_ADAPTIVE)
+    {
+        if (tt->standby_iter == IPW32_SET_ADAPTIVE_TRY_NETSH)
+        {
+            msg(M_INFO, "NOTE: now trying netsh (this may take some time)");
+            netsh_ifconfig(&tt->options,
+                           tt->actual_name,
+                           tt->local,
+                           tt->adapter_netmask,
+                           NI_TEST_FIRST|NI_IP_NETMASK|NI_OPTIONS);
+        }
+        else if (tt->standby_iter >= IPW32_SET_ADAPTIVE_TRY_NETSH*2)
+        {
+            ret = false;
+        }
+    }
+    return ret;
+}
+
+/*
+ * Convert DHCP options from the command line / config file
+ * into a raw DHCP-format options string.
+ */
+
+static void
+write_dhcp_u8(struct buffer *buf, const int type, const int data, bool *error)
+{
+    if (!buf_safe(buf, 3))
+    {
+        *error = true;
+        msg(M_WARN, "write_dhcp_u8: buffer overflow building DHCP options");
+        return;
+    }
+    buf_write_u8(buf, type);
+    buf_write_u8(buf, 1);
+    buf_write_u8(buf, data);
+}
+
+static void
+write_dhcp_u32_array(struct buffer *buf, const int type, const uint32_t *data, const unsigned int len, bool *error)
+{
+    if (len > 0)
+    {
+        int i;
+        const int size = len * sizeof(uint32_t);
+
+        if (!buf_safe(buf, 2 + size))
+        {
+            *error = true;
+            msg(M_WARN, "write_dhcp_u32_array: buffer overflow building DHCP options");
+            return;
+        }
+        if (size < 1 || size > 255)
+        {
+            *error = true;
+            msg(M_WARN, "write_dhcp_u32_array: size (%d) must be > 0 and <= 255", size);
+            return;
+        }
+        buf_write_u8(buf, type);
+        buf_write_u8(buf, size);
+        for (i = 0; i < len; ++i)
+        {
+            buf_write_u32(buf, data[i]);
+        }
+    }
+}
+
+static void
+write_dhcp_str(struct buffer *buf, const int type, const char *str, bool *error)
+{
+    const int len = strlen(str);
+    if (!buf_safe(buf, 2 + len))
+    {
+        *error = true;
+        msg(M_WARN, "write_dhcp_str: buffer overflow building DHCP options");
+        return;
+    }
+    if (len < 1 || len > 255)
+    {
+        *error = true;
+        msg(M_WARN, "write_dhcp_str: string '%s' must be > 0 bytes and <= 255 bytes", str);
+        return;
+    }
+    buf_write_u8(buf, type);
+    buf_write_u8(buf, len);
+    buf_write(buf, str, len);
+}
+
+static bool
+build_dhcp_options_string(struct buffer *buf, const struct tuntap_options *o)
+{
+    bool error = false;
+    if (o->domain)
+    {
+        write_dhcp_str(buf, 15, o->domain, &error);
+    }
+
+    if (o->netbios_scope)
+    {
+        write_dhcp_str(buf, 47, o->netbios_scope, &error);
+    }
+
+    if (o->netbios_node_type)
+    {
+        write_dhcp_u8(buf, 46, o->netbios_node_type, &error);
+    }
+
+    write_dhcp_u32_array(buf, 6, (uint32_t *)o->dns, o->dns_len, &error);
+    write_dhcp_u32_array(buf, 44, (uint32_t *)o->wins, o->wins_len, &error);
+    write_dhcp_u32_array(buf, 42, (uint32_t *)o->ntp, o->ntp_len, &error);
+    write_dhcp_u32_array(buf, 45, (uint32_t *)o->nbdd, o->nbdd_len, &error);
+
+    /* the MS DHCP server option 'Disable Netbios-over-TCP/IP
+     * is implemented as vendor option 001, value 002.
+     * A value of 001 means 'leave NBT alone' which is the default */
+    if (o->disable_nbt)
+    {
+        if (!buf_safe(buf, 8))
+        {
+            msg(M_WARN, "build_dhcp_options_string: buffer overflow building DHCP options");
+            return false;
+        }
+        buf_write_u8(buf,  43);
+        buf_write_u8(buf,  6);/* total length field */
+        buf_write_u8(buf,  0x001);
+        buf_write_u8(buf,  4);/* length of the vendor specified field */
+        buf_write_u32(buf, 0x002);
+    }
+    return !error;
+}
+
+static void
+fork_dhcp_action(struct tuntap *tt)
+{
+    if (tt->options.dhcp_pre_release || tt->options.dhcp_renew)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer cmd = alloc_buf_gc(256, &gc);
+        const int verb = 3;
+        const int pre_sleep = 1;
+
+        buf_printf(&cmd, "openvpn --verb %d --tap-sleep %d", verb, pre_sleep);
+        if (tt->options.dhcp_pre_release)
+        {
+            buf_printf(&cmd, " --dhcp-pre-release");
+        }
+        if (tt->options.dhcp_renew)
+        {
+            buf_printf(&cmd, " --dhcp-renew");
+        }
+        buf_printf(&cmd, " --dhcp-internal %u", (unsigned int)tt->adapter_index);
+
+        fork_to_self(BSTR(&cmd));
+        gc_free(&gc);
+    }
+}
+
+static void
+register_dns_service(const struct tuntap *tt)
+{
+    DWORD len;
+    HANDLE msg_channel = tt->options.msg_channel;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+
+    message_header_t rdns = { msg_register_dns, sizeof(message_header_t), 0 };
+
+    if (!WriteFile(msg_channel, &rdns, sizeof(rdns), &len, NULL)
+        || !ReadFile(msg_channel, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "Register_dns: could not talk to service: %s [status=0x%lx]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+    }
+
+    else if (ack.error_number != NO_ERROR)
+    {
+        msg(M_WARN, "Register_dns failed using service: %s [status=0x%x]",
+            strerror_win32(ack.error_number, &gc), ack.error_number);
+    }
+
+    else
+    {
+        msg(M_INFO, "Register_dns request sent to the service");
+    }
+
+    gc_free(&gc);
+}
+
+void
+fork_register_dns_action(struct tuntap *tt)
+{
+    if (tt && tt->options.register_dns && tt->options.msg_channel)
+    {
+        register_dns_service(tt);
+    }
+    else if (tt && tt->options.register_dns)
+    {
+        struct gc_arena gc = gc_new();
+        struct buffer cmd = alloc_buf_gc(256, &gc);
+        const int verb = 3;
+
+        buf_printf(&cmd, "openvpn --verb %d --register-dns --rdns-internal", verb);
+        fork_to_self(BSTR(&cmd));
+        gc_free(&gc);
+    }
+}
+
+static uint32_t
+dhcp_masq_addr(const in_addr_t local, const in_addr_t netmask, const int offset)
+{
+    struct gc_arena gc = gc_new();
+    in_addr_t dsa; /* DHCP server addr */
+
+    if (offset < 0)
+    {
+        dsa = (local | (~netmask)) + offset;
+    }
+    else
+    {
+        dsa = (local & netmask) + offset;
+    }
+
+    if (dsa == local)
+    {
+        msg(M_FATAL, "ERROR: There is a clash between the --ifconfig local address and the internal DHCP server address -- both are set to %s -- please use the --ip-win32 dynamic option to choose a different free address from the --ifconfig subnet for the internal DHCP server", print_in_addr_t(dsa, 0, &gc));
+    }
+
+    if ((local & netmask) != (dsa & netmask))
+    {
+        msg(M_FATAL, "ERROR: --ip-win32 dynamic [offset] : offset is outside of --ifconfig subnet");
+    }
+
+    gc_free(&gc);
+    return htonl(dsa);
+}
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+    char device_path[256];
+    const char *device_guid = NULL;
+    DWORD len;
+    bool dhcp_masq = false;
+    bool dhcp_masq_post = false;
+
+    /*netcmd_semaphore_lock ();*/
+
+    msg( M_INFO, "open_tun");
+
+    if (tt->type == DEV_TYPE_NULL)
+    {
+        open_null(tt);
+        gc_free(&gc);
+        return;
+    }
+    else if (tt->type == DEV_TYPE_TAP || tt->type == DEV_TYPE_TUN)
+    {
+    }
+    else
+    {
+        msg(M_FATAL|M_NOPREFIX, "Unknown virtual device type: '%s'", dev);
+    }
+
+    /*
+     * Lookup the device name in the registry, using the --dev-node high level name.
+     */
+    {
+        const struct tap_reg *tap_reg = get_tap_reg(&gc);
+        const struct panel_reg *panel_reg = get_panel_reg(&gc);
+        char actual_buffer[256];
+
+        at_least_one_tap_win(tap_reg);
+
+        if (dev_node)
+        {
+            /* Get the device GUID for the device specified with --dev-node. */
+            device_guid = get_device_guid(dev_node, actual_buffer, sizeof(actual_buffer), tap_reg, panel_reg, &gc);
+
+            if (!device_guid)
+            {
+                msg(M_FATAL, "TAP-Windows adapter '%s' not found", dev_node);
+            }
+
+            /* Open Windows TAP-Windows adapter */
+            openvpn_snprintf(device_path, sizeof(device_path), "%s%s%s",
+                             USERMODEDEVICEDIR,
+                             device_guid,
+                             TAP_WIN_SUFFIX);
+
+            tt->hand = CreateFile(
+                device_path,
+                GENERIC_READ | GENERIC_WRITE,
+                0,                /* was: FILE_SHARE_READ */
+                0,
+                OPEN_EXISTING,
+                FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
+                0
+                );
+
+            if (tt->hand == INVALID_HANDLE_VALUE)
+            {
+                msg(M_ERR, "CreateFile failed on TAP device: %s", device_path);
+            }
+        }
+        else
+        {
+            int device_number = 0;
+
+            /* Try opening all TAP devices until we find one available */
+            while (true)
+            {
+                device_guid = get_unspecified_device_guid(device_number,
+                                                          actual_buffer,
+                                                          sizeof(actual_buffer),
+                                                          tap_reg,
+                                                          panel_reg,
+                                                          &gc);
+
+                if (!device_guid)
+                {
+                    msg(M_FATAL, "All TAP-Windows adapters on this system are currently in use.");
+                }
+
+                /* Open Windows TAP-Windows adapter */
+                openvpn_snprintf(device_path, sizeof(device_path), "%s%s%s",
+                                 USERMODEDEVICEDIR,
+                                 device_guid,
+                                 TAP_WIN_SUFFIX);
+
+                tt->hand = CreateFile(
+                    device_path,
+                    GENERIC_READ | GENERIC_WRITE,
+                    0,                /* was: FILE_SHARE_READ */
+                    0,
+                    OPEN_EXISTING,
+                    FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED,
+                    0
+                    );
+
+                if (tt->hand == INVALID_HANDLE_VALUE)
+                {
+                    msg(D_TUNTAP_INFO, "CreateFile failed on TAP device: %s", device_path);
+                }
+                else
+                {
+                    break;
+                }
+
+                device_number++;
+            }
+        }
+
+        /* translate high-level device name into a device instance
+         * GUID using the registry */
+        tt->actual_name = string_alloc(actual_buffer, NULL);
+    }
+
+    msg(M_INFO, "TAP-WIN32 device [%s] opened: %s", tt->actual_name, device_path);
+    tt->adapter_index = get_adapter_index(device_guid);
+
+    /* get driver version info */
+    {
+        ULONG info[3];
+        CLEAR(info);
+        if (DeviceIoControl(tt->hand, TAP_WIN_IOCTL_GET_VERSION,
+                            &info, sizeof(info),
+                            &info, sizeof(info), &len, NULL))
+        {
+            msg(D_TUNTAP_INFO, "TAP-Windows Driver Version %d.%d %s",
+                (int) info[0],
+                (int) info[1],
+                (info[2] ? "(DEBUG)" : ""));
+
+        }
+        if (!(info[0] == TAP_WIN_MIN_MAJOR && info[1] >= TAP_WIN_MIN_MINOR))
+        {
+            msg(M_FATAL, "ERROR:  This version of " PACKAGE_NAME " requires a TAP-Windows driver that is at least version %d.%d -- If you recently upgraded your " PACKAGE_NAME " distribution, a reboot is probably required at this point to get Windows to see the new driver.",
+                TAP_WIN_MIN_MAJOR,
+                TAP_WIN_MIN_MINOR);
+        }
+
+        /* usage of numeric constants is ugly, but this is really tied to
+         * *this* version of the driver
+         */
+        if (tt->type == DEV_TYPE_TUN
+            && info[0] == 9 && info[1] < 8)
+        {
+            msg( M_INFO, "WARNING:  Tap-Win32 driver version %d.%d does not support IPv6 in TUN mode. IPv6 will not work. Upgrade your Tap-Win32 driver.", (int) info[0], (int) info[1] );
+        }
+
+        /* tap driver 9.8 (2.2.0 and 2.2.1 release) is buggy
+         */
+        if (tt->type == DEV_TYPE_TUN
+            && info[0] == 9 && info[1] == 8)
+        {
+            msg( M_FATAL, "ERROR:  Tap-Win32 driver version %d.%d is buggy regarding small IPv4 packets in TUN mode. Upgrade your Tap-Win32 driver.", (int) info[0], (int) info[1] );
+        }
+    }
+
+    /* get driver MTU */
+    {
+        ULONG mtu;
+        if (DeviceIoControl(tt->hand, TAP_WIN_IOCTL_GET_MTU,
+                            &mtu, sizeof(mtu),
+                            &mtu, sizeof(mtu), &len, NULL))
+        {
+            tt->post_open_mtu = (int) mtu;
+            msg(D_MTU_INFO, "TAP-Windows MTU=%d", (int) mtu);
+        }
+    }
+
+    /*
+     * Preliminaries for setting TAP-Windows adapter TCP/IP
+     * properties via --ip-win32 dynamic or --ip-win32 adaptive.
+     */
+    if (tt->did_ifconfig_setup)
+    {
+        if (tt->options.ip_win32_type == IPW32_SET_DHCP_MASQ)
+        {
+            /*
+             * If adapter is set to non-DHCP, set to DHCP mode.
+             */
+            if (dhcp_status(tt->adapter_index) == DHCP_STATUS_DISABLED)
+            {
+                /* try using the service if available, else directly execute netsh */
+                if (tt->options.msg_channel)
+                {
+                    service_enable_dhcp(tt);
+                }
+                else
+                {
+                    netsh_enable_dhcp(tt->actual_name);
+                }
+            }
+            dhcp_masq = true;
+            dhcp_masq_post = true;
+        }
+        else if (tt->options.ip_win32_type == IPW32_SET_ADAPTIVE)
+        {
+            /*
+             * If adapter is set to non-DHCP, use netsh right away.
+             */
+            if (dhcp_status(tt->adapter_index) != DHCP_STATUS_ENABLED)
+            {
+                netsh_ifconfig(&tt->options,
+                               tt->actual_name,
+                               tt->local,
+                               tt->adapter_netmask,
+                               NI_TEST_FIRST|NI_IP_NETMASK|NI_OPTIONS);
+            }
+            else
+            {
+                dhcp_masq = true;
+            }
+        }
+    }
+
+    /* set point-to-point mode if TUN device */
+
+    if (tt->type == DEV_TYPE_TUN)
+    {
+        if (!tt->did_ifconfig_setup)
+        {
+            msg(M_FATAL, "ERROR: --dev tun also requires --ifconfig");
+        }
+
+        if (tt->topology == TOP_SUBNET)
+        {
+            in_addr_t ep[3];
+            BOOL status;
+
+            ep[0] = htonl(tt->local);
+            ep[1] = htonl(tt->local & tt->remote_netmask);
+            ep[2] = htonl(tt->remote_netmask);
+
+            status = DeviceIoControl(tt->hand, TAP_WIN_IOCTL_CONFIG_TUN,
+                                     ep, sizeof(ep),
+                                     ep, sizeof(ep), &len, NULL);
+
+            msg(status ? M_INFO : M_FATAL, "Set TAP-Windows TUN subnet mode network/local/netmask = %s/%s/%s [%s]",
+                print_in_addr_t(ep[1], IA_NET_ORDER, &gc),
+                print_in_addr_t(ep[0], IA_NET_ORDER, &gc),
+                print_in_addr_t(ep[2], IA_NET_ORDER, &gc),
+                status ? "SUCCEEDED" : "FAILED");
+
+        }
+        else
+        {
+
+            in_addr_t ep[2];
+            ep[0] = htonl(tt->local);
+            ep[1] = htonl(tt->remote_netmask);
+
+            if (!DeviceIoControl(tt->hand, TAP_WIN_IOCTL_CONFIG_POINT_TO_POINT,
+                                 ep, sizeof(ep),
+                                 ep, sizeof(ep), &len, NULL))
+            {
+                msg(M_FATAL, "ERROR: The TAP-Windows driver rejected a DeviceIoControl call to set Point-to-Point mode, which is required for --dev tun");
+            }
+        }
+    }
+
+    /* should we tell the TAP-Windows driver to masquerade as a DHCP server as a means
+     * of setting the adapter address? */
+    if (dhcp_masq)
+    {
+        uint32_t ep[4];
+
+        /* We will answer DHCP requests with a reply to set IP/subnet to these values */
+        ep[0] = htonl(tt->local);
+        ep[1] = htonl(tt->adapter_netmask);
+
+        /* At what IP address should the DHCP server masquerade at? */
+        if (tt->type == DEV_TYPE_TUN)
+        {
+            if (tt->topology == TOP_SUBNET)
+            {
+                if (tt->options.dhcp_masq_custom_offset)
+                {
+                    ep[2] = dhcp_masq_addr(tt->local, tt->remote_netmask, tt->options.dhcp_masq_offset);
+                }
+                else
+                {
+                    ep[2] = dhcp_masq_addr(tt->local, tt->remote_netmask, -1);
+                }
+            }
+            else
+            {
+                ep[2] = htonl(tt->remote_netmask);
+            }
+        }
+        else
+        {
+            ASSERT(tt->type == DEV_TYPE_TAP);
+            ep[2] = dhcp_masq_addr(tt->local, tt->adapter_netmask, tt->options.dhcp_masq_custom_offset ? tt->options.dhcp_masq_offset : 0);
+        }
+
+        /* lease time in seconds */
+        ep[3] = (uint32_t) tt->options.dhcp_lease_time;
+
+        ASSERT(ep[3] > 0);
+
+#ifndef SIMULATE_DHCP_FAILED /* this code is disabled to simulate bad DHCP negotiation */
+        if (!DeviceIoControl(tt->hand, TAP_WIN_IOCTL_CONFIG_DHCP_MASQ,
+                             ep, sizeof(ep),
+                             ep, sizeof(ep), &len, NULL))
+        {
+            msg(M_FATAL, "ERROR: The TAP-Windows driver rejected a DeviceIoControl call to set TAP_WIN_IOCTL_CONFIG_DHCP_MASQ mode");
+        }
+
+        msg(M_INFO, "Notified TAP-Windows driver to set a DHCP IP/netmask of %s/%s on interface %s [DHCP-serv: %s, lease-time: %d]",
+            print_in_addr_t(tt->local, 0, &gc),
+            print_in_addr_t(tt->adapter_netmask, 0, &gc),
+            device_guid,
+            print_in_addr_t(ep[2], IA_NET_ORDER, &gc),
+            ep[3]
+            );
+
+        /* user-supplied DHCP options capability */
+        if (tt->options.dhcp_options)
+        {
+            struct buffer buf = alloc_buf(256);
+            if (build_dhcp_options_string(&buf, &tt->options))
+            {
+                msg(D_DHCP_OPT, "DHCP option string: %s", format_hex(BPTR(&buf), BLEN(&buf), 0, &gc));
+                if (!DeviceIoControl(tt->hand, TAP_WIN_IOCTL_CONFIG_DHCP_SET_OPT,
+                                     BPTR(&buf), BLEN(&buf),
+                                     BPTR(&buf), BLEN(&buf), &len, NULL))
+                {
+                    msg(M_FATAL, "ERROR: The TAP-Windows driver rejected a TAP_WIN_IOCTL_CONFIG_DHCP_SET_OPT DeviceIoControl call");
+                }
+            }
+            else
+            {
+                msg(M_WARN, "DHCP option string not set due to error");
+            }
+            free_buf(&buf);
+        }
+#endif /* ifndef SIMULATE_DHCP_FAILED */
+    }
+
+    /* set driver media status to 'connected' */
+    {
+        ULONG status = TRUE;
+        if (!DeviceIoControl(tt->hand, TAP_WIN_IOCTL_SET_MEDIA_STATUS,
+                             &status, sizeof(status),
+                             &status, sizeof(status), &len, NULL))
+        {
+            msg(M_WARN, "WARNING: The TAP-Windows driver rejected a TAP_WIN_IOCTL_SET_MEDIA_STATUS DeviceIoControl call.");
+        }
+    }
+
+    /* possible wait for adapter to come up */
+    {
+        int s = tt->options.tap_sleep;
+        if (s > 0)
+        {
+            msg(M_INFO, "Sleeping for %d seconds...", s);
+            management_sleep(s);
+        }
+    }
+
+    /* possibly use IP Helper API to set IP address on adapter */
+    {
+        const DWORD index = tt->adapter_index;
+
+        /* flush arp cache */
+        if (index != TUN_ADAPTER_INDEX_INVALID)
+        {
+            DWORD status = -1;
+
+            if (tt->options.msg_channel)
+            {
+                ack_message_t ack;
+                flush_neighbors_message_t msg = {
+                    .header = {
+                        msg_flush_neighbors,
+                        sizeof(flush_neighbors_message_t),
+                        0
+                    },
+                    .family = AF_INET,
+                    .iface = { .index = index, .name = "" }
+                };
+
+                if (!WriteFile(tt->options.msg_channel, &msg, sizeof(msg), &len, NULL)
+                    || !ReadFile(tt->options.msg_channel, &ack, sizeof(ack), &len, NULL))
+                {
+                    msg(M_WARN, "TUN: could not talk to service: %s [%lu]",
+                        strerror_win32(GetLastError(), &gc), GetLastError());
+                }
+
+                status = ack.error_number;
+            }
+            else
+            {
+                status = FlushIpNetTable(index);
+            }
+
+            if (status == NO_ERROR)
+            {
+                msg(M_INFO, "Successful ARP Flush on interface [%u] %s",
+                    (unsigned int)index,
+                    device_guid);
+            }
+            else if (status != -1)
+            {
+                msg(D_TUNTAP_INFO, "NOTE: FlushIpNetTable failed on interface [%u] %s (status=%u) : %s",
+                    (unsigned int)index,
+                    device_guid,
+                    (unsigned int)status,
+                    strerror_win32(status, &gc));
+            }
+        }
+
+        /*
+         * If the TAP-Windows driver is masquerading as a DHCP server
+         * make sure the TCP/IP properties for the adapter are
+         * set correctly.
+         */
+        if (dhcp_masq_post)
+        {
+            /* check dhcp enable status */
+            if (dhcp_status(index) == DHCP_STATUS_DISABLED)
+            {
+                msg(M_WARN, "WARNING: You have selected '--ip-win32 dynamic', which will not work unless the TAP-Windows TCP/IP properties are set to 'Obtain an IP address automatically'");
+            }
+
+            /* force an explicit DHCP lease renewal on TAP adapter? */
+            if (tt->options.dhcp_pre_release)
+            {
+                dhcp_release(tt);
+            }
+            if (tt->options.dhcp_renew)
+            {
+                dhcp_renew(tt);
+            }
+        }
+        else
+        {
+            fork_dhcp_action(tt);
+        }
+
+        if (tt->did_ifconfig_setup && tt->options.ip_win32_type == IPW32_SET_IPAPI)
+        {
+            DWORD status;
+            const char *error_suffix = "I am having trouble using the Windows 'IP helper API' to automatically set the IP address -- consider using other --ip-win32 methods (not 'ipapi')";
+
+            /* couldn't get adapter index */
+            if (index == TUN_ADAPTER_INDEX_INVALID)
+            {
+                msg(M_FATAL, "ERROR: unable to get adapter index for interface %s -- %s",
+                    device_guid,
+                    error_suffix);
+            }
+
+            /* check dhcp enable status */
+            if (dhcp_status(index) == DHCP_STATUS_DISABLED)
+            {
+                msg(M_WARN, "NOTE: You have selected (explicitly or by default) '--ip-win32 ipapi', which has a better chance of working correctly if the TAP-Windows TCP/IP properties are set to 'Obtain an IP address automatically'");
+            }
+
+            /* delete previously added IP addresses which were not
+             * correctly deleted */
+            delete_temp_addresses(index);
+
+            /* add a new IP address */
+            if ((status = AddIPAddress(htonl(tt->local),
+                                       htonl(tt->adapter_netmask),
+                                       index,
+                                       &tt->ipapi_context,
+                                       &tt->ipapi_instance)) == NO_ERROR)
+            {
+                msg(M_INFO, "Succeeded in adding a temporary IP/netmask of %s/%s to interface %s using the Win32 IP Helper API",
+                    print_in_addr_t(tt->local, 0, &gc),
+                    print_in_addr_t(tt->adapter_netmask, 0, &gc),
+                    device_guid
+                    );
+            }
+            else
+            {
+                msg(M_FATAL, "ERROR: AddIPAddress %s/%s failed on interface %s, index=%d, status=%u (windows error: '%s') -- %s",
+                    print_in_addr_t(tt->local, 0, &gc),
+                    print_in_addr_t(tt->adapter_netmask, 0, &gc),
+                    device_guid,
+                    (int)index,
+                    (unsigned int)status,
+                    strerror_win32(status, &gc),
+                    error_suffix);
+            }
+            tt->ipapi_context_defined = true;
+        }
+    }
+    /*netcmd_semaphore_release ();*/
+    gc_free(&gc);
+}
+
+const char *
+tap_win_getinfo(const struct tuntap *tt, struct gc_arena *gc)
+{
+    if (tt && tt->hand != NULL)
+    {
+        struct buffer out = alloc_buf_gc(256, gc);
+        DWORD len;
+        if (DeviceIoControl(tt->hand, TAP_WIN_IOCTL_GET_INFO,
+                            BSTR(&out), BCAP(&out),
+                            BSTR(&out), BCAP(&out),
+                            &len, NULL))
+        {
+            return BSTR(&out);
+        }
+    }
+    return NULL;
+}
+
+void
+tun_show_debug(struct tuntap *tt)
+{
+    if (tt && tt->hand != NULL)
+    {
+        struct buffer out = alloc_buf(1024);
+        DWORD len;
+        while (DeviceIoControl(tt->hand, TAP_WIN_IOCTL_GET_LOG_LINE,
+                               BSTR(&out), BCAP(&out),
+                               BSTR(&out), BCAP(&out),
+                               &len, NULL))
+        {
+            msg(D_TAP_WIN_DEBUG, "TAP-Windows: %s", BSTR(&out));
+        }
+        free_buf(&out);
+    }
+}
+
+void
+close_tun(struct tuntap *tt)
+{
+    struct gc_arena gc = gc_new();
+
+    if (tt)
+    {
+        if (tt->did_ifconfig_ipv6_setup)
+        {
+            /* remove route pointing to interface */
+            delete_route_connected_v6_net(tt, NULL);
+
+            if (tt->options.msg_channel)
+            {
+                do_address_service(false, AF_INET6, tt);
+                if (tt->options.dns6_len > 0)
+                {
+                    do_dns6_service(false, tt);
+                }
+            }
+            else
+            {
+                const char *ifconfig_ipv6_local;
+                struct argv argv = argv_new();
+
+                /* "store=active" is needed in Windows 8(.1) to delete the
+                 * address we added (pointed out by Cedric Tabary).
+                 */
+
+                /* netsh interface ipv6 delete address \"%s\" %s */
+                ifconfig_ipv6_local = print_in6_addr(tt->local_ipv6, 0,  &gc);
+                argv_printf(&argv,
+                            "%s%sc interface ipv6 delete address %s %s store=active",
+                            get_win_sys_path(),
+                            NETSH_PATH_SUFFIX,
+                            tt->actual_name,
+                            ifconfig_ipv6_local);
+
+                netsh_command(&argv, 1, M_WARN);
+
+                /* delete ipv6 dns servers if any were set */
+                if (tt->options.dns6_len > 0)
+                {
+                    argv_printf(&argv,
+                                "%s%sc interface ipv6 delete dns %s all",
+                                get_win_sys_path(),
+                                NETSH_PATH_SUFFIX,
+                                tt->actual_name);
+                    netsh_command(&argv, 1, M_WARN);
+                }
+                argv_reset(&argv);
+            }
+        }
+#if 1
+        if (tt->ipapi_context_defined)
+        {
+            DWORD status;
+            if ((status = DeleteIPAddress(tt->ipapi_context)) != NO_ERROR)
+            {
+                msg(M_WARN, "Warning: DeleteIPAddress[%u] failed on TAP-Windows adapter, status=%u : %s",
+                    (unsigned int)tt->ipapi_context,
+                    (unsigned int)status,
+                    strerror_win32(status, &gc));
+            }
+        }
+#endif
+
+        dhcp_release(tt);
+
+        if (tt->hand != NULL)
+        {
+            dmsg(D_WIN32_IO_LOW, "Attempting CancelIO on TAP-Windows adapter");
+            if (!CancelIo(tt->hand))
+            {
+                msg(M_WARN | M_ERRNO, "Warning: CancelIO failed on TAP-Windows adapter");
+            }
+        }
+
+        dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped read event on TAP-Windows adapter");
+        overlapped_io_close(&tt->reads);
+
+        dmsg(D_WIN32_IO_LOW, "Attempting close of overlapped write event on TAP-Windows adapter");
+        overlapped_io_close(&tt->writes);
+
+        if (tt->hand != NULL)
+        {
+            dmsg(D_WIN32_IO_LOW, "Attempting CloseHandle on TAP-Windows adapter");
+            if (!CloseHandle(tt->hand))
+            {
+                msg(M_WARN | M_ERRNO, "Warning: CloseHandle failed on TAP-Windows adapter");
+            }
+        }
+
+        if (tt->actual_name)
+        {
+            free(tt->actual_name);
+        }
+
+        clear_tuntap(tt);
+        free(tt);
+    }
+    gc_free(&gc);
+}
+
+/*
+ * Convert --ip-win32 constants between index and ascii form.
+ */
+
+struct ipset_names {
+    const char *short_form;
+};
+
+/* Indexed by IPW32_SET_x */
+static const struct ipset_names ipset_names[] = {
+    {"manual"},
+    {"netsh"},
+    {"ipapi"},
+    {"dynamic"},
+    {"adaptive"}
+};
+
+int
+ascii2ipset(const char *name)
+{
+    int i;
+    ASSERT(IPW32_SET_N == SIZE(ipset_names));
+    for (i = 0; i < IPW32_SET_N; ++i)
+    {
+        if (!strcmp(name, ipset_names[i].short_form))
+        {
+            return i;
+        }
+    }
+    return -1;
+}
+
+const char *
+ipset2ascii(int index)
+{
+    ASSERT(IPW32_SET_N == SIZE(ipset_names));
+    if (index < 0 || index >= IPW32_SET_N)
+    {
+        return "[unknown --ip-win32 type]";
+    }
+    else
+    {
+        return ipset_names[index].short_form;
+    }
+}
+
+const char *
+ipset2ascii_all(struct gc_arena *gc)
+{
+    struct buffer out = alloc_buf_gc(256, gc);
+    int i;
+
+    ASSERT(IPW32_SET_N == SIZE(ipset_names));
+    for (i = 0; i < IPW32_SET_N; ++i)
+    {
+        if (i)
+        {
+            buf_printf(&out, " ");
+        }
+        buf_printf(&out, "[%s]", ipset2ascii(i));
+    }
+    return BSTR(&out);
+}
+
+#else /* generic */
+
+void
+open_tun(const char *dev, const char *dev_type, const char *dev_node, struct tuntap *tt)
+{
+    open_tun_generic(dev, dev_type, dev_node, true, tt);
+}
+
+void
+close_tun(struct tuntap *tt)
+{
+    if (tt)
+    {
+        close_tun_generic(tt);
+        free(tt);
+    }
+}
+
+int
+write_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return write(tt->fd, buf, len);
+}
+
+int
+read_tun(struct tuntap *tt, uint8_t *buf, int len)
+{
+    return read(tt->fd, buf, len);
+}
+
+#endif /* if defined (TARGET_ANDROID) */
diff --git a/src/openvpn/tun.h b/src/openvpn/tun.h
new file mode 100644
index 0000000..54e1dfa
--- /dev/null
+++ b/src/openvpn/tun.h
@@ -0,0 +1,538 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef TUN_H
+#define TUN_H
+
+#ifdef _WIN32
+#include <winioctl.h>
+#include <tap-windows.h>
+#endif
+
+#include "buffer.h"
+#include "error.h"
+#include "mtu.h"
+#include "win32.h"
+#include "event.h"
+#include "proto.h"
+#include "misc.h"
+
+#if defined(_WIN32) || defined(TARGET_ANDROID)
+
+#define TUN_ADAPTER_INDEX_INVALID ((DWORD)-1)
+
+/* time constants for --ip-win32 adaptive */
+#define IPW32_SET_ADAPTIVE_DELAY_WINDOW 300
+#define IPW32_SET_ADAPTIVE_TRY_NETSH    20
+
+struct tuntap_options {
+    /* --ip-win32 options */
+    bool ip_win32_defined;
+
+#define IPW32_SET_MANUAL       0   /* "--ip-win32 manual" */
+#define IPW32_SET_NETSH        1   /* "--ip-win32 netsh" */
+#define IPW32_SET_IPAPI        2   /* "--ip-win32 ipapi" */
+#define IPW32_SET_DHCP_MASQ    3   /* "--ip-win32 dynamic" */
+#define IPW32_SET_ADAPTIVE     4   /* "--ip-win32 adaptive" */
+#define IPW32_SET_N            5
+    int ip_win32_type;
+
+#ifdef _WIN32
+    HANDLE msg_channel;
+#endif
+
+    /* --ip-win32 dynamic options */
+    bool dhcp_masq_custom_offset;
+    int dhcp_masq_offset;
+    int dhcp_lease_time;
+
+    /* --tap-sleep option */
+    int tap_sleep;
+
+    /* --dhcp-option options */
+
+    bool dhcp_options;
+
+    const char *domain;      /* DOMAIN (15) */
+
+    const char *netbios_scope; /* NBS (47) */
+
+    int netbios_node_type;   /* NBT 1,2,4,8 (46) */
+
+#define N_DHCP_ADDR 4        /* Max # of addresses allowed for
+                              * DNS, WINS, etc. */
+
+    /* DNS (6) */
+    in_addr_t dns[N_DHCP_ADDR];
+    int dns_len;
+
+    /* WINS (44) */
+    in_addr_t wins[N_DHCP_ADDR];
+    int wins_len;
+
+    /* NTP (42) */
+    in_addr_t ntp[N_DHCP_ADDR];
+    int ntp_len;
+
+    /* NBDD (45) */
+    in_addr_t nbdd[N_DHCP_ADDR];
+    int nbdd_len;
+
+    /* DISABLE_NBT (43, Vendor option 001) */
+    bool disable_nbt;
+
+    bool dhcp_renew;
+    bool dhcp_pre_release;
+
+    bool register_dns;
+
+    struct in6_addr dns6[N_DHCP_ADDR];
+    int dns6_len;
+};
+
+#elif TARGET_LINUX
+
+struct tuntap_options {
+    int txqueuelen;
+};
+
+#else  /* if defined(_WIN32) || defined(TARGET_ANDROID) */
+
+struct tuntap_options {
+    int dummy; /* not used */
+};
+
+#endif /* if defined(_WIN32) || defined(TARGET_ANDROID) */
+
+/*
+ * Define a TUN/TAP dev.
+ */
+
+struct tuntap
+{
+#define TUNNEL_TYPE(tt) ((tt) ? ((tt)->type) : DEV_TYPE_UNDEF)
+    int type; /* DEV_TYPE_x as defined in proto.h */
+
+#define TUNNEL_TOPOLOGY(tt) ((tt) ? ((tt)->topology) : TOP_UNDEF)
+    int topology; /* one of the TOP_x values */
+
+    bool did_ifconfig_setup;
+    bool did_ifconfig_ipv6_setup;
+    bool did_ifconfig;
+
+    bool persistent_if;         /* if existed before, keep on program end */
+
+    struct tuntap_options options; /* options set on command line */
+
+    char *actual_name; /* actual name of TUN/TAP dev, usually including unit number */
+
+    /* number of TX buffers */
+    int txqueuelen;
+
+    /* ifconfig parameters */
+    in_addr_t local;
+    in_addr_t remote_netmask;
+    in_addr_t broadcast;
+
+    struct in6_addr local_ipv6;
+    struct in6_addr remote_ipv6;
+    int netbits_ipv6;
+
+#ifdef _WIN32
+    HANDLE hand;
+    struct overlapped_io reads;
+    struct overlapped_io writes;
+    struct rw_handle rw_handle;
+
+    /* used for setting interface address via IP Helper API
+     * or DHCP masquerade */
+    bool ipapi_context_defined;
+    ULONG ipapi_context;
+    ULONG ipapi_instance;
+    in_addr_t adapter_netmask;
+
+    /* Windows adapter index for TAP-Windows adapter,
+     * ~0 if undefined */
+    DWORD adapter_index;
+
+    int standby_iter;
+#else  /* ifdef _WIN32 */
+    int fd; /* file descriptor for TUN/TAP dev */
+#endif
+
+#ifdef TARGET_SOLARIS
+    int ip_fd;
+#endif
+
+#ifdef HAVE_NET_IF_UTUN_H
+    bool is_utun;
+#endif
+    /* used for printing status info only */
+    unsigned int rwflags_debug;
+
+    /* Some TUN/TAP drivers like to be ioctled for mtu
+     * after open */
+    int post_open_mtu;
+};
+
+static inline bool
+tuntap_defined(const struct tuntap *tt)
+{
+#ifdef _WIN32
+    return tt && tt->hand != NULL;
+#else
+    return tt && tt->fd >= 0;
+#endif
+}
+
+/*
+ * Function prototypes
+ */
+
+void open_tun(const char *dev, const char *dev_type, const char *dev_node,
+              struct tuntap *tt);
+
+void close_tun(struct tuntap *tt);
+
+int write_tun(struct tuntap *tt, uint8_t *buf, int len);
+
+int read_tun(struct tuntap *tt, uint8_t *buf, int len);
+
+void tuncfg(const char *dev, const char *dev_type, const char *dev_node,
+            int persist_mode, const char *username,
+            const char *groupname, const struct tuntap_options *options);
+
+const char *guess_tuntap_dev(const char *dev,
+                             const char *dev_type,
+                             const char *dev_node,
+                             struct gc_arena *gc);
+
+struct tuntap *init_tun(const char *dev,        /* --dev option */
+                        const char *dev_type,   /* --dev-type option */
+                        int topology,           /* one of the TOP_x values */
+                        const char *ifconfig_local_parm,           /* --ifconfig parm 1 */
+                        const char *ifconfig_remote_netmask_parm,  /* --ifconfig parm 2 */
+                        const char *ifconfig_ipv6_local_parm,      /* --ifconfig parm 1 / IPv6 */
+                        int ifconfig_ipv6_netbits_parm,            /* --ifconfig parm 1 / bits */
+                        const char *ifconfig_ipv6_remote_parm,     /* --ifconfig parm 2 / IPv6 */
+                        struct addrinfo *local_public,
+                        struct addrinfo *remote_public,
+                        const bool strict_warn,
+                        struct env_set *es);
+
+void init_tun_post(struct tuntap *tt,
+                   const struct frame *frame,
+                   const struct tuntap_options *options);
+
+void do_ifconfig_setenv(const struct tuntap *tt,
+                        struct env_set *es);
+
+void do_ifconfig(struct tuntap *tt,
+                 const char *actual,     /* actual device name */
+                 int tun_mtu,
+                 const struct env_set *es);
+
+bool is_dev_type(const char *dev, const char *dev_type, const char *match_type);
+
+int dev_type_enum(const char *dev, const char *dev_type);
+
+const char *dev_type_string(const char *dev, const char *dev_type);
+
+const char *ifconfig_options_string(const struct tuntap *tt, bool remote, bool disable, struct gc_arena *gc);
+
+bool is_tun_p2p(const struct tuntap *tt);
+
+void check_subnet_conflict(const in_addr_t ip,
+                           const in_addr_t netmask,
+                           const char *prefix);
+
+void warn_on_use_of_common_subnets(void);
+
+/*
+ * Inline functions
+ */
+
+static inline void
+tun_adjust_frame_parameters(struct frame *frame, int size)
+{
+    frame_add_to_extra_tun(frame, size);
+}
+
+/*
+ * Should ifconfig be called before or after
+ * tun dev open?
+ */
+
+#define IFCONFIG_BEFORE_TUN_OPEN 0
+#define IFCONFIG_AFTER_TUN_OPEN  1
+
+#define IFCONFIG_DEFAULT         IFCONFIG_AFTER_TUN_OPEN
+
+static inline int
+ifconfig_order(void)
+{
+#if defined(TARGET_LINUX)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(TARGET_SOLARIS)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(TARGET_OPENBSD)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(TARGET_DARWIN)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(TARGET_NETBSD)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(_WIN32)
+    return IFCONFIG_AFTER_TUN_OPEN;
+#elif defined(TARGET_ANDROID)
+    return IFCONFIG_BEFORE_TUN_OPEN;
+#else  /* if defined(TARGET_LINUX) */
+    return IFCONFIG_DEFAULT;
+#endif
+}
+
+#define ROUTE_BEFORE_TUN 0
+#define ROUTE_AFTER_TUN 1
+#define ROUTE_ORDER_DEFAULT ROUTE_AFTER_TUN
+
+static inline int
+route_order(void)
+{
+#if defined(TARGET_ANDROID)
+    return ROUTE_BEFORE_TUN;
+#else
+    return ROUTE_ORDER_DEFAULT;
+#endif
+}
+
+
+#ifdef _WIN32
+
+#define TUN_PASS_BUFFER
+
+struct tap_reg
+{
+    const char *guid;
+    struct tap_reg *next;
+};
+
+struct panel_reg
+{
+    const char *name;
+    const char *guid;
+    struct panel_reg *next;
+};
+
+int ascii2ipset(const char *name);
+
+const char *ipset2ascii(int index);
+
+const char *ipset2ascii_all(struct gc_arena *gc);
+
+void verify_255_255_255_252(in_addr_t local, in_addr_t remote);
+
+const IP_ADAPTER_INFO *get_adapter_info_list(struct gc_arena *gc);
+
+const IP_ADAPTER_INFO *get_tun_adapter(const struct tuntap *tt, const IP_ADAPTER_INFO *list);
+
+const IP_ADAPTER_INFO *get_adapter_info(DWORD index, struct gc_arena *gc);
+
+const IP_PER_ADAPTER_INFO *get_per_adapter_info(const DWORD index, struct gc_arena *gc);
+
+const IP_ADAPTER_INFO *get_adapter(const IP_ADAPTER_INFO *ai, DWORD index);
+
+bool is_adapter_up(const struct tuntap *tt, const IP_ADAPTER_INFO *list);
+
+bool is_ip_in_adapter_subnet(const IP_ADAPTER_INFO *ai, const in_addr_t ip, in_addr_t *highest_netmask);
+
+DWORD adapter_index_of_ip(const IP_ADAPTER_INFO *list,
+                          const in_addr_t ip,
+                          int *count,
+                          in_addr_t *netmask);
+
+void show_tap_win_adapters(int msglev, int warnlev);
+
+void show_adapters(int msglev);
+
+void tap_allow_nonadmin_access(const char *dev_node);
+
+void show_valid_win32_tun_subnets(void);
+
+const char *tap_win_getinfo(const struct tuntap *tt, struct gc_arena *gc);
+
+void tun_show_debug(struct tuntap *tt);
+
+bool dhcp_release_by_adapter_index(const DWORD adapter_index);
+
+bool dhcp_renew_by_adapter_index(const DWORD adapter_index);
+
+void fork_register_dns_action(struct tuntap *tt);
+
+void ipconfig_register_dns(const struct env_set *es);
+
+void tun_standby_init(struct tuntap *tt);
+
+bool tun_standby(struct tuntap *tt);
+
+int tun_read_queue(struct tuntap *tt, int maxsize);
+
+int tun_write_queue(struct tuntap *tt, struct buffer *buf);
+
+int tun_finalize(HANDLE h, struct overlapped_io *io, struct buffer *buf);
+
+static inline bool
+tuntap_stop(int status)
+{
+    /*
+     * This corresponds to the STATUS_NO_SUCH_DEVICE
+     * error in tapdrvr.c.
+     */
+    if (status < 0)
+    {
+        return openvpn_errno() == ERROR_FILE_NOT_FOUND;
+    }
+    return false;
+}
+
+static inline bool
+tuntap_abort(int status)
+{
+    /*
+     * Typically generated when driver is halted.
+     */
+    if (status < 0)
+    {
+        return openvpn_errno() == ERROR_OPERATION_ABORTED;
+    }
+    return false;
+}
+
+static inline int
+tun_write_win32(struct tuntap *tt, struct buffer *buf)
+{
+    int err = 0;
+    int status = 0;
+    if (overlapped_io_active(&tt->writes))
+    {
+        status = tun_finalize(tt->hand, &tt->writes, NULL);
+        if (status < 0)
+        {
+            err = GetLastError();
+        }
+    }
+    tun_write_queue(tt, buf);
+    if (status < 0)
+    {
+        SetLastError(err);
+        return status;
+    }
+    else
+    {
+        return BLEN(buf);
+    }
+}
+
+static inline int
+read_tun_buffered(struct tuntap *tt, struct buffer *buf)
+{
+    return tun_finalize(tt->hand, &tt->reads, buf);
+}
+
+static inline int
+write_tun_buffered(struct tuntap *tt, struct buffer *buf)
+{
+    return tun_write_win32(tt, buf);
+}
+
+#else  /* ifdef _WIN32 */
+
+static inline bool
+tuntap_stop(int status)
+{
+    return false;
+}
+
+static inline bool
+tuntap_abort(int status)
+{
+    return false;
+}
+
+static inline void
+tun_standby_init(struct tuntap *tt)
+{
+}
+
+static inline bool
+tun_standby(struct tuntap *tt)
+{
+    return true;
+}
+
+#endif /* ifdef _WIN32 */
+
+/*
+ * TUN/TAP I/O wait functions
+ */
+
+static inline event_t
+tun_event_handle(const struct tuntap *tt)
+{
+#ifdef _WIN32
+    return &tt->rw_handle;
+#else
+    return tt->fd;
+#endif
+}
+
+static inline unsigned int
+tun_set(struct tuntap *tt,
+        struct event_set *es,
+        unsigned int rwflags,
+        void *arg,
+        unsigned int *persistent)
+{
+    if (tuntap_defined(tt))
+    {
+        /* if persistent is defined, call event_ctl only if rwflags has changed since last call */
+        if (!persistent || *persistent != rwflags)
+        {
+            event_ctl(es, tun_event_handle(tt), rwflags, arg);
+            if (persistent)
+            {
+                *persistent = rwflags;
+            }
+        }
+#ifdef _WIN32
+        if (rwflags & EVENT_READ)
+        {
+            tun_read_queue(tt, 0);
+        }
+#endif
+        tt->rwflags_debug = rwflags;
+    }
+    return rwflags;
+}
+
+const char *tun_stat(const struct tuntap *tt, unsigned int rwflags, struct gc_arena *gc);
+
+#endif /* TUN_H */
diff --git a/src/openvpn/win32.c b/src/openvpn/win32.c
new file mode 100644
index 0000000..f13807f
--- /dev/null
+++ b/src/openvpn/win32.c
@@ -0,0 +1,1479 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * Win32-specific OpenVPN code, targetted at the mingw
+ * development environment.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#ifdef _WIN32
+
+#include "buffer.h"
+#include "error.h"
+#include "mtu.h"
+#include "sig.h"
+#include "win32.h"
+#include "misc.h"
+#include "openvpn-msg.h"
+
+#include "memdbg.h"
+
+#ifdef HAVE_VERSIONHELPERS_H
+#include <versionhelpers.h>
+#else
+#include "compat-versionhelpers.h"
+#endif
+
+#include "block_dns.h"
+
+/*
+ * WFP handle
+ */
+static HANDLE m_hEngineHandle = NULL; /* GLOBAL */
+
+/*
+ * TAP adapter original metric value
+ */
+static int tap_metric_v4 = -1; /* GLOBAL */
+static int tap_metric_v6 = -1; /* GLOBAL */
+
+/*
+ * Windows internal socket API state (opaque).
+ */
+static struct WSAData wsa_state; /* GLOBAL */
+
+/*
+ * Should we call win32_pause() on program exit?
+ */
+static bool pause_exit_enabled = false; /* GLOBAL */
+
+/*
+ * win32_signal is used to get input from the keyboard
+ * if we are running in a console, or get input from an
+ * event object if we are running as a service.
+ */
+
+struct win32_signal win32_signal; /* GLOBAL */
+
+/*
+ * Save our old window title so we can restore
+ * it on exit.
+ */
+struct window_title window_title; /* GLOBAL*/
+
+/*
+ * Special global semaphore used to protect network
+ * shell commands from simultaneous instantiation.
+ */
+
+struct semaphore netcmd_semaphore; /* GLOBAL */
+
+/*
+ * Windows system pathname such as c:\windows
+ */
+static char *win_sys_path = NULL; /* GLOBAL */
+
+void
+init_win32(void)
+{
+    if (WSAStartup(0x0101, &wsa_state))
+    {
+        msg(M_ERR, "WSAStartup failed");
+    }
+    window_title_clear(&window_title);
+    win32_signal_clear(&win32_signal);
+}
+
+void
+uninit_win32(void)
+{
+    netcmd_semaphore_close();
+    if (pause_exit_enabled)
+    {
+        if (win32_signal.mode == WSO_MODE_UNDEF)
+        {
+            struct win32_signal w;
+            win32_signal_open(&w, WSO_FORCE_CONSOLE, NULL, false);
+            win32_pause(&w);
+            win32_signal_close(&w);
+        }
+        else
+        {
+            win32_pause(&win32_signal);
+        }
+    }
+    window_title_restore(&window_title);
+    win32_signal_close(&win32_signal);
+    WSACleanup();
+    free(win_sys_path);
+}
+
+void
+set_pause_exit_win32(void)
+{
+    pause_exit_enabled = true;
+}
+
+bool
+init_security_attributes_allow_all(struct security_attributes *obj)
+{
+    CLEAR(*obj);
+
+    obj->sa.nLength = sizeof(SECURITY_ATTRIBUTES);
+    obj->sa.lpSecurityDescriptor = &obj->sd;
+    obj->sa.bInheritHandle = FALSE;
+    if (!InitializeSecurityDescriptor(&obj->sd, SECURITY_DESCRIPTOR_REVISION))
+    {
+        return false;
+    }
+    if (!SetSecurityDescriptorDacl(&obj->sd, TRUE, NULL, FALSE))
+    {
+        return false;
+    }
+    return true;
+}
+
+void
+overlapped_io_init(struct overlapped_io *o,
+                   const struct frame *frame,
+                   BOOL event_state,
+                   bool tuntap_buffer)  /* if true: tuntap buffer, if false: socket buffer */
+{
+    CLEAR(*o);
+
+    /* manual reset event, initially set according to event_state */
+    o->overlapped.hEvent = CreateEvent(NULL, TRUE, event_state, NULL);
+    if (o->overlapped.hEvent == NULL)
+    {
+        msg(M_ERR, "Error: overlapped_io_init: CreateEvent failed");
+    }
+
+    /* allocate buffer for overlapped I/O */
+    alloc_buf_sock_tun(&o->buf_init, frame, tuntap_buffer, 0);
+}
+
+void
+overlapped_io_close(struct overlapped_io *o)
+{
+    if (o->overlapped.hEvent)
+    {
+        if (!CloseHandle(o->overlapped.hEvent))
+        {
+            msg(M_WARN | M_ERRNO, "Warning: CloseHandle failed on overlapped I/O event object");
+        }
+    }
+    free_buf(&o->buf_init);
+}
+
+char *
+overlapped_io_state_ascii(const struct overlapped_io *o)
+{
+    switch (o->iostate)
+    {
+        case IOSTATE_INITIAL:
+            return "0";
+
+        case IOSTATE_QUEUED:
+            return "Q";
+
+        case IOSTATE_IMMEDIATE_RETURN:
+            return "1";
+    }
+    return "?";
+}
+
+/*
+ * Event-based notification of network events
+ */
+
+void
+init_net_event_win32(struct rw_handle *event, long network_events, socket_descriptor_t sd, unsigned int flags)
+{
+    /* manual reset events, initially set to unsignaled */
+
+    /* initialize write event */
+    if (!(flags & NE32_PERSIST_EVENT) || !event->write)
+    {
+        if (flags & NE32_WRITE_EVENT)
+        {
+            event->write = CreateEvent(NULL, TRUE, FALSE, NULL);
+            if (event->write == NULL)
+            {
+                msg(M_ERR, "Error: init_net_event_win32: CreateEvent (write) failed");
+            }
+        }
+        else
+        {
+            event->write = NULL;
+        }
+    }
+
+    /* initialize read event */
+    if (!(flags & NE32_PERSIST_EVENT) || !event->read)
+    {
+        event->read = CreateEvent(NULL, TRUE, FALSE, NULL);
+        if (event->read == NULL)
+        {
+            msg(M_ERR, "Error: init_net_event_win32: CreateEvent (read) failed");
+        }
+    }
+
+    /* setup network events to change read event state */
+    if (WSAEventSelect(sd, event->read, network_events) != 0)
+    {
+        msg(M_FATAL | M_ERRNO, "Error: init_net_event_win32: WSAEventSelect call failed");
+    }
+}
+
+long
+reset_net_event_win32(struct rw_handle *event, socket_descriptor_t sd)
+{
+    WSANETWORKEVENTS wne;
+    if (WSAEnumNetworkEvents(sd, event->read, &wne) != 0)
+    {
+        msg(M_FATAL | M_ERRNO, "Error: reset_net_event_win32: WSAEnumNetworkEvents call failed");
+        return 0; /* NOTREACHED */
+    }
+    else
+    {
+        return wne.lNetworkEvents;
+    }
+}
+
+void
+close_net_event_win32(struct rw_handle *event, socket_descriptor_t sd, unsigned int flags)
+{
+    if (event->read)
+    {
+        if (socket_defined(sd))
+        {
+            if (WSAEventSelect(sd, event->read, 0) != 0)
+            {
+                msg(M_WARN | M_ERRNO, "Warning: close_net_event_win32: WSAEventSelect call failed");
+            }
+        }
+        if (!ResetEvent(event->read))
+        {
+            msg(M_WARN | M_ERRNO, "Warning: ResetEvent (read) failed in close_net_event_win32");
+        }
+        if (!(flags & NE32_PERSIST_EVENT))
+        {
+            if (!CloseHandle(event->read))
+            {
+                msg(M_WARN | M_ERRNO, "Warning: CloseHandle (read) failed in close_net_event_win32");
+            }
+            event->read = NULL;
+        }
+    }
+
+    if (event->write)
+    {
+        if (!ResetEvent(event->write))
+        {
+            msg(M_WARN | M_ERRNO, "Warning: ResetEvent (write) failed in close_net_event_win32");
+        }
+        if (!(flags & NE32_PERSIST_EVENT))
+        {
+            if (!CloseHandle(event->write))
+            {
+                msg(M_WARN | M_ERRNO, "Warning: CloseHandle (write) failed in close_net_event_win32");
+            }
+            event->write = NULL;
+        }
+    }
+}
+
+/*
+ * struct net_event_win32
+ */
+
+void
+net_event_win32_init(struct net_event_win32 *ne)
+{
+    CLEAR(*ne);
+    ne->sd = SOCKET_UNDEFINED;
+}
+
+void
+net_event_win32_start(struct net_event_win32 *ne, long network_events, socket_descriptor_t sd)
+{
+    ASSERT(!socket_defined(ne->sd));
+    ne->sd = sd;
+    ne->event_mask = 0;
+    init_net_event_win32(&ne->handle, network_events, sd, NE32_PERSIST_EVENT|NE32_WRITE_EVENT);
+}
+
+void
+net_event_win32_reset_write(struct net_event_win32 *ne)
+{
+    BOOL status;
+    if (ne->event_mask & FD_WRITE)
+    {
+        status = SetEvent(ne->handle.write);
+    }
+    else
+    {
+        status = ResetEvent(ne->handle.write);
+    }
+    if (!status)
+    {
+        msg(M_WARN | M_ERRNO, "Warning: SetEvent/ResetEvent failed in net_event_win32_reset_write");
+    }
+}
+
+void
+net_event_win32_reset(struct net_event_win32 *ne)
+{
+    ne->event_mask |= reset_net_event_win32(&ne->handle, ne->sd);
+}
+
+void
+net_event_win32_stop(struct net_event_win32 *ne)
+{
+    if (net_event_win32_defined(ne))
+    {
+        close_net_event_win32(&ne->handle, ne->sd, NE32_PERSIST_EVENT);
+    }
+    ne->sd = SOCKET_UNDEFINED;
+    ne->event_mask = 0;
+}
+
+void
+net_event_win32_close(struct net_event_win32 *ne)
+{
+    if (net_event_win32_defined(ne))
+    {
+        close_net_event_win32(&ne->handle, ne->sd, 0);
+    }
+    net_event_win32_init(ne);
+}
+
+/*
+ * Simulate *nix signals on Windows.
+ *
+ * Two modes:
+ * (1) Console mode -- map keyboard function keys to signals
+ * (2) Service mode -- map Windows event object to SIGTERM
+ */
+
+static void
+win_trigger_event(struct win32_signal *ws)
+{
+    if (ws->mode == WSO_MODE_SERVICE && HANDLE_DEFINED(ws->in.read))
+    {
+        SetEvent(ws->in.read);
+    }
+    else /* generate a key-press event */
+    {
+        DWORD tmp;
+        INPUT_RECORD ir;
+        HANDLE stdin_handle = GetStdHandle(STD_INPUT_HANDLE);
+
+        CLEAR(ir);
+        ir.EventType = KEY_EVENT;
+        ir.Event.KeyEvent.bKeyDown = true;
+        if (!stdin_handle || !WriteConsoleInput(stdin_handle, &ir, 1, &tmp))
+        {
+            msg(M_WARN|M_ERRNO, "WARN: win_trigger_event: WriteConsoleInput");
+        }
+    }
+}
+
+/*
+ * Callback to handle console ctrl events
+ */
+static bool WINAPI
+win_ctrl_handler(DWORD signum)
+{
+    msg(D_LOW, "win_ctrl_handler: signal received (code=%lu)", (unsigned long) signum);
+
+    if (siginfo_static.signal_received == SIGTERM)
+    {
+        return true;
+    }
+
+    switch (signum)
+    {
+        case CTRL_C_EVENT:
+        case CTRL_BREAK_EVENT:
+            throw_signal(SIGTERM);
+            /* trigget the win32_signal to interrupt the event loop */
+            win_trigger_event(&win32_signal);
+            return true;
+            break;
+
+        default:
+            msg(D_LOW, "win_ctrl_handler: signal (code=%lu) not handled", (unsigned long) signum);
+            break;
+    }
+    /* pass all other signals to the next handler */
+    return false;
+}
+
+void
+win32_signal_clear(struct win32_signal *ws)
+{
+    CLEAR(*ws);
+}
+
+void
+win32_signal_open(struct win32_signal *ws,
+                  int force,
+                  const char *exit_event_name,
+                  bool exit_event_initial_state)
+{
+    CLEAR(*ws);
+
+    ws->mode = WSO_MODE_UNDEF;
+    ws->in.read = INVALID_HANDLE_VALUE;
+    ws->in.write = INVALID_HANDLE_VALUE;
+    ws->console_mode_save = 0;
+    ws->console_mode_save_defined = false;
+
+    if (force == WSO_NOFORCE || force == WSO_FORCE_CONSOLE)
+    {
+        /*
+         * Try to open console.
+         */
+        ws->in.read = GetStdHandle(STD_INPUT_HANDLE);
+        if (ws->in.read != INVALID_HANDLE_VALUE)
+        {
+            if (GetConsoleMode(ws->in.read, &ws->console_mode_save))
+            {
+                /* running on a console */
+                const DWORD new_console_mode = ws->console_mode_save
+                                               & ~(ENABLE_WINDOW_INPUT
+                                                   | ENABLE_PROCESSED_INPUT
+                                                   | ENABLE_LINE_INPUT
+                                                   | ENABLE_ECHO_INPUT
+                                                   | ENABLE_MOUSE_INPUT);
+
+                if (new_console_mode != ws->console_mode_save)
+                {
+                    if (!SetConsoleMode(ws->in.read, new_console_mode))
+                    {
+                        msg(M_ERR, "Error: win32_signal_open: SetConsoleMode failed");
+                    }
+                    ws->console_mode_save_defined = true;
+                }
+                ws->mode = WSO_MODE_CONSOLE;
+            }
+            else
+            {
+                ws->in.read = INVALID_HANDLE_VALUE; /* probably running as a service */
+            }
+        }
+    }
+
+    /*
+     * If console open failed, assume we are running
+     * as a service.
+     */
+    if ((force == WSO_NOFORCE || force == WSO_FORCE_SERVICE)
+        && !HANDLE_DEFINED(ws->in.read) && exit_event_name)
+    {
+        struct security_attributes sa;
+
+        if (!init_security_attributes_allow_all(&sa))
+        {
+            msg(M_ERR, "Error: win32_signal_open: init SA failed");
+        }
+
+        ws->in.read = CreateEvent(&sa.sa,
+                                  TRUE,
+                                  exit_event_initial_state ? TRUE : FALSE,
+                                  exit_event_name);
+        if (ws->in.read == NULL)
+        {
+            msg(M_WARN|M_ERRNO, "NOTE: CreateEvent '%s' failed", exit_event_name);
+        }
+        else
+        {
+            if (WaitForSingleObject(ws->in.read, 0) != WAIT_TIMEOUT)
+            {
+                msg(M_FATAL, "ERROR: Exit Event ('%s') is signaled", exit_event_name);
+            }
+            else
+            {
+                ws->mode = WSO_MODE_SERVICE;
+            }
+        }
+    }
+    /* set the ctrl handler in both console and service modes */
+    if (!SetConsoleCtrlHandler((PHANDLER_ROUTINE) win_ctrl_handler, true))
+    {
+        msg(M_WARN|M_ERRNO, "WARN: SetConsoleCtrlHandler failed");
+    }
+}
+
+static bool
+keyboard_input_available(struct win32_signal *ws)
+{
+    ASSERT(ws->mode == WSO_MODE_CONSOLE);
+    if (HANDLE_DEFINED(ws->in.read))
+    {
+        DWORD n;
+        if (GetNumberOfConsoleInputEvents(ws->in.read, &n))
+        {
+            return n > 0;
+        }
+    }
+    return false;
+}
+
+static unsigned int
+keyboard_ir_to_key(INPUT_RECORD *ir)
+{
+    if (ir->Event.KeyEvent.uChar.AsciiChar == 0)
+    {
+        return ir->Event.KeyEvent.wVirtualScanCode;
+    }
+
+    if ((ir->Event.KeyEvent.dwControlKeyState
+         & (LEFT_ALT_PRESSED | RIGHT_ALT_PRESSED))
+        && (ir->Event.KeyEvent.wVirtualKeyCode != 18))
+    {
+        return ir->Event.KeyEvent.wVirtualScanCode * 256;
+    }
+
+    return ir->Event.KeyEvent.uChar.AsciiChar;
+}
+
+static unsigned int
+win32_keyboard_get(struct win32_signal *ws)
+{
+    ASSERT(ws->mode == WSO_MODE_CONSOLE);
+    if (HANDLE_DEFINED(ws->in.read))
+    {
+        INPUT_RECORD ir;
+        do
+        {
+            DWORD n;
+            if (!keyboard_input_available(ws))
+            {
+                return 0;
+            }
+            if (!ReadConsoleInput(ws->in.read, &ir, 1, &n))
+            {
+                return 0;
+            }
+        } while (ir.EventType != KEY_EVENT || ir.Event.KeyEvent.bKeyDown != TRUE);
+
+        return keyboard_ir_to_key(&ir);
+    }
+    else
+    {
+        return 0;
+    }
+}
+
+void
+win32_signal_close(struct win32_signal *ws)
+{
+    if (ws->mode == WSO_MODE_SERVICE && HANDLE_DEFINED(ws->in.read))
+    {
+        CloseHandle(ws->in.read);
+    }
+    if (ws->console_mode_save_defined)
+    {
+        if (!SetConsoleMode(ws->in.read, ws->console_mode_save))
+        {
+            msg(M_ERR, "Error: win32_signal_close: SetConsoleMode failed");
+        }
+    }
+    CLEAR(*ws);
+}
+
+/*
+ * Return true if interrupt occurs in service mode.
+ */
+bool
+win32_service_interrupt(struct win32_signal *ws)
+{
+    if (ws->mode == WSO_MODE_SERVICE)
+    {
+        if (HANDLE_DEFINED(ws->in.read)
+            && WaitForSingleObject(ws->in.read, 0) == WAIT_OBJECT_0)
+        {
+            return true;
+        }
+    }
+    return false;
+}
+
+int
+win32_signal_get(struct win32_signal *ws)
+{
+    int ret = 0;
+    if (siginfo_static.signal_received)
+    {
+        ret = siginfo_static.signal_received;
+    }
+    else
+    {
+        if (ws->mode == WSO_MODE_SERVICE)
+        {
+            if (win32_service_interrupt(ws))
+            {
+                ret = SIGTERM;
+            }
+        }
+        else if (ws->mode == WSO_MODE_CONSOLE)
+        {
+            switch (win32_keyboard_get(ws))
+            {
+                case 0x3B: /* F1 -> USR1 */
+                    ret = SIGUSR1;
+                    break;
+
+                case 0x3C: /* F2 -> USR2 */
+                    ret = SIGUSR2;
+                    break;
+
+                case 0x3D: /* F3 -> HUP */
+                    ret = SIGHUP;
+                    break;
+
+                case 0x3E: /* F4 -> TERM */
+                    ret = SIGTERM;
+                    break;
+
+                case 0x03: /* CTRL-C -> TERM */
+                    ret = SIGTERM;
+                    break;
+            }
+        }
+        if (ret)
+        {
+            siginfo_static.signal_received = ret;
+            siginfo_static.source = SIG_SOURCE_HARD;
+        }
+    }
+    return ret;
+}
+
+void
+win32_pause(struct win32_signal *ws)
+{
+    if (ws->mode == WSO_MODE_CONSOLE && HANDLE_DEFINED(ws->in.read))
+    {
+        msg(M_INFO|M_NOPREFIX, "Press any key to continue...");
+        do
+        {
+            WaitForSingleObject(ws->in.read, INFINITE);
+        } while (!win32_keyboard_get(ws));
+    }
+}
+
+/* window functions */
+
+void
+window_title_clear(struct window_title *wt)
+{
+    CLEAR(*wt);
+}
+
+void
+window_title_save(struct window_title *wt)
+{
+    if (!wt->saved)
+    {
+        if (!GetConsoleTitle(wt->old_window_title, sizeof(wt->old_window_title)))
+        {
+            wt->old_window_title[0] = 0;
+            wt->saved = false;
+        }
+        else
+        {
+            wt->saved = true;
+        }
+    }
+}
+
+void
+window_title_restore(const struct window_title *wt)
+{
+    if (wt->saved)
+    {
+        SetConsoleTitle(wt->old_window_title);
+    }
+}
+
+void
+window_title_generate(const char *title)
+{
+    struct gc_arena gc = gc_new();
+    struct buffer out = alloc_buf_gc(256, &gc);
+    if (!title)
+    {
+        title = "";
+    }
+    buf_printf(&out, "[%s] " PACKAGE_NAME " " PACKAGE_VERSION " F4:EXIT F1:USR1 F2:USR2 F3:HUP", title);
+    SetConsoleTitle(BSTR(&out));
+    gc_free(&gc);
+}
+
+/* semaphore functions */
+
+void
+semaphore_clear(struct semaphore *s)
+{
+    CLEAR(*s);
+}
+
+void
+semaphore_open(struct semaphore *s, const char *name)
+{
+    struct security_attributes sa;
+
+    s->locked = false;
+    s->name = name;
+    s->hand = NULL;
+
+    if (init_security_attributes_allow_all(&sa))
+    {
+        s->hand = CreateSemaphore(&sa.sa, 1, 1, name);
+    }
+
+    if (s->hand == NULL)
+    {
+        msg(M_WARN|M_ERRNO, "WARNING: Cannot create Win32 semaphore '%s'", name);
+    }
+    else
+    {
+        dmsg(D_SEMAPHORE, "Created Win32 semaphore '%s'", s->name);
+    }
+}
+
+bool
+semaphore_lock(struct semaphore *s, int timeout_milliseconds)
+{
+    bool ret = true;
+
+    if (s->hand)
+    {
+        DWORD status;
+        ASSERT(!s->locked);
+
+        dmsg(D_SEMAPHORE_LOW, "Attempting to lock Win32 semaphore '%s' prior to net shell command (timeout = %d sec)",
+             s->name,
+             timeout_milliseconds / 1000);
+        status = WaitForSingleObject(s->hand, timeout_milliseconds);
+        if (status == WAIT_FAILED)
+        {
+            msg(M_ERR, "Wait failed on Win32 semaphore '%s'", s->name);
+        }
+        ret = (status == WAIT_TIMEOUT) ? false : true;
+        if (ret)
+        {
+            dmsg(D_SEMAPHORE, "Locked Win32 semaphore '%s'", s->name);
+            s->locked = true;
+        }
+        else
+        {
+            dmsg(D_SEMAPHORE, "Wait on Win32 semaphore '%s' timed out after %d milliseconds",
+                 s->name,
+                 timeout_milliseconds);
+        }
+    }
+    return ret;
+}
+
+void
+semaphore_release(struct semaphore *s)
+{
+    if (s->hand)
+    {
+        ASSERT(s->locked);
+        dmsg(D_SEMAPHORE, "Releasing Win32 semaphore '%s'", s->name);
+        if (!ReleaseSemaphore(s->hand, 1, NULL))
+        {
+            msg(M_WARN | M_ERRNO, "ReleaseSemaphore failed on Win32 semaphore '%s'",
+                s->name);
+        }
+        s->locked = false;
+    }
+}
+
+void
+semaphore_close(struct semaphore *s)
+{
+    if (s->hand)
+    {
+        if (s->locked)
+        {
+            semaphore_release(s);
+        }
+        dmsg(D_SEMAPHORE, "Closing Win32 semaphore '%s'", s->name);
+        CloseHandle(s->hand);
+        s->hand = NULL;
+    }
+}
+
+/*
+ * Special global semaphore used to protect network
+ * shell commands from simultaneous instantiation.
+ */
+
+void
+netcmd_semaphore_init(void)
+{
+    semaphore_open(&netcmd_semaphore, PACKAGE "_netcmd");
+}
+
+void
+netcmd_semaphore_close(void)
+{
+    semaphore_close(&netcmd_semaphore);
+}
+
+void
+netcmd_semaphore_lock(void)
+{
+    const int timeout_seconds = 600;
+
+    if (!netcmd_semaphore.hand)
+    {
+        netcmd_semaphore_init();
+    }
+
+    if (!semaphore_lock(&netcmd_semaphore, timeout_seconds * 1000))
+    {
+        msg(M_FATAL, "Cannot lock net command semaphore");
+    }
+}
+
+void
+netcmd_semaphore_release(void)
+{
+    semaphore_release(&netcmd_semaphore);
+    /* netcmd_semaphore has max count of 1 - safe to close after release */
+    semaphore_close(&netcmd_semaphore);
+}
+
+/*
+ * Return true if filename is safe to be used on Windows,
+ * by avoiding the following reserved names:
+ *
+ * CON, PRN, AUX, NUL, COM1, COM2, COM3, COM4, COM5, COM6, COM7, COM8, COM9,
+ * LPT1, LPT2, LPT3, LPT4, LPT5, LPT6, LPT7, LPT8, LPT9, and CLOCK$
+ *
+ * See: http://msdn.microsoft.com/en-us/library/aa365247.aspx
+ *  and http://msdn.microsoft.com/en-us/library/86k9f82k(VS.80).aspx
+ */
+
+static bool
+cmp_prefix(const char *str, const bool n, const char *pre)
+{
+    size_t i = 0;
+
+    if (!str)
+    {
+        return false;
+    }
+
+    while (true)
+    {
+        const int c1 = pre[i];
+        int c2 = str[i];
+        ++i;
+        if (c1 == '\0')
+        {
+            if (n)
+            {
+                if (isdigit(c2))
+                {
+                    c2 = str[i];
+                }
+                else
+                {
+                    return false;
+                }
+            }
+            return c2 == '\0' || c2 == '.';
+        }
+        else if (c2 == '\0')
+        {
+            return false;
+        }
+        if (c1 != tolower(c2))
+        {
+            return false;
+        }
+    }
+}
+
+bool
+win_safe_filename(const char *fn)
+{
+    if (cmp_prefix(fn, false, "con"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, false, "prn"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, false, "aux"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, false, "nul"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, true, "com"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, true, "lpt"))
+    {
+        return false;
+    }
+    if (cmp_prefix(fn, false, "clock$"))
+    {
+        return false;
+    }
+    return true;
+}
+
+/*
+ * Service functions for openvpn_execve
+ */
+
+static char *
+env_block(const struct env_set *es)
+{
+    char force_path[256];
+    char *sysroot = get_win_sys_path();
+
+    if (!openvpn_snprintf(force_path, sizeof(force_path), "PATH=%s\\System32;%s;%s\\System32\\Wbem",
+                          sysroot, sysroot, sysroot))
+    {
+        msg(M_WARN, "env_block: default path truncated to %s", force_path);
+    }
+
+    if (es)
+    {
+        struct env_item *e;
+        char *ret;
+        char *p;
+        size_t nchars = 1;
+        bool path_seen = false;
+
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            nchars += strlen(e->string) + 1;
+        }
+
+        nchars += strlen(force_path)+1;
+
+        ret = (char *) malloc(nchars);
+        check_malloc_return(ret);
+
+        p = ret;
+        for (e = es->list; e != NULL; e = e->next)
+        {
+            if (env_allowed(e->string))
+            {
+                strcpy(p, e->string);
+                p += strlen(e->string) + 1;
+            }
+            if (strncmp(e->string, "PATH=", 5 ) == 0)
+            {
+                path_seen = true;
+            }
+        }
+
+        /* make sure PATH is set */
+        if (!path_seen)
+        {
+            msg( M_INFO, "env_block: add %s", force_path );
+            strcpy( p, force_path );
+            p += strlen(force_path) + 1;
+        }
+
+        *p = '\0';
+        return ret;
+    }
+    else
+    {
+        return NULL;
+    }
+}
+
+static WCHAR *
+wide_cmd_line(const struct argv *a, struct gc_arena *gc)
+{
+    size_t nchars = 1;
+    size_t maxlen = 0;
+    size_t i;
+    struct buffer buf;
+    char *work = NULL;
+
+    if (!a)
+    {
+        return NULL;
+    }
+
+    for (i = 0; i < a->argc; ++i)
+    {
+        const char *arg = a->argv[i];
+        const size_t len = strlen(arg);
+        nchars += len + 3;
+        if (len > maxlen)
+        {
+            maxlen = len;
+        }
+    }
+
+    work = gc_malloc(maxlen + 1, false, gc);
+    check_malloc_return(work);
+    buf = alloc_buf_gc(nchars, gc);
+
+    for (i = 0; i < a->argc; ++i)
+    {
+        const char *arg = a->argv[i];
+        strcpy(work, arg);
+        string_mod(work, CC_PRINT, CC_DOUBLE_QUOTE|CC_CRLF, '_');
+        if (i)
+        {
+            buf_printf(&buf, " ");
+        }
+        if (string_class(work, CC_ANY, CC_SPACE))
+        {
+            buf_printf(&buf, "%s", work);
+        }
+        else
+        {
+            buf_printf(&buf, "\"%s\"", work);
+        }
+    }
+
+    return wide_string(BSTR(&buf), gc);
+}
+
+/*
+ * Attempt to simulate fork/execve on Windows
+ */
+int
+openvpn_execve(const struct argv *a, const struct env_set *es, const unsigned int flags)
+{
+    int ret = OPENVPN_EXECVE_ERROR;
+    static bool exec_warn = false;
+
+    if (a && a->argv[0])
+    {
+        if (openvpn_execve_allowed(flags))
+        {
+            struct gc_arena gc = gc_new();
+            STARTUPINFOW start_info;
+            PROCESS_INFORMATION proc_info;
+
+            char *env = env_block(es);
+            WCHAR *cl = wide_cmd_line(a, &gc);
+            WCHAR *cmd = wide_string(a->argv[0], &gc);
+
+            /* this allows console programs to run, and is ignored otherwise */
+            DWORD proc_flags = CREATE_NO_WINDOW;
+
+            CLEAR(start_info);
+            CLEAR(proc_info);
+
+            /* fill in STARTUPINFO struct */
+            GetStartupInfoW(&start_info);
+            start_info.cb = sizeof(start_info);
+            start_info.dwFlags = STARTF_USESHOWWINDOW;
+            start_info.wShowWindow = SW_HIDE;
+
+            if (CreateProcessW(cmd, cl, NULL, NULL, FALSE, proc_flags, env, NULL, &start_info, &proc_info))
+            {
+                DWORD exit_status = 0;
+                CloseHandle(proc_info.hThread);
+                WaitForSingleObject(proc_info.hProcess, INFINITE);
+                if (GetExitCodeProcess(proc_info.hProcess, &exit_status))
+                {
+                    ret = (int)exit_status;
+                }
+                else
+                {
+                    msg(M_WARN|M_ERRNO, "openvpn_execve: GetExitCodeProcess %S failed", cmd);
+                }
+                CloseHandle(proc_info.hProcess);
+            }
+            else
+            {
+                msg(M_WARN|M_ERRNO, "openvpn_execve: CreateProcess %S failed", cmd);
+            }
+            free(env);
+            gc_free(&gc);
+        }
+        else
+        {
+            ret = OPENVPN_EXECVE_NOT_ALLOWED;
+            if (!exec_warn && (script_security < SSEC_SCRIPTS))
+            {
+                msg(M_WARN, SCRIPT_SECURITY_WARNING);
+                exec_warn = true;
+            }
+        }
+    }
+    else
+    {
+        msg(M_WARN, "openvpn_execve: called with empty argv");
+    }
+    return ret;
+}
+
+WCHAR *
+wide_string(const char *utf8, struct gc_arena *gc)
+{
+    int n = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
+    WCHAR *ucs16 = gc_malloc(n * sizeof(WCHAR), false, gc);
+    MultiByteToWideChar(CP_UTF8, 0, utf8, -1, ucs16, n);
+    return ucs16;
+}
+
+/*
+ * call ourself in another process
+ */
+void
+fork_to_self(const char *cmdline)
+{
+    STARTUPINFO start_info;
+    PROCESS_INFORMATION proc_info;
+    char self_exe[256];
+    char *cl = string_alloc(cmdline, NULL);
+    DWORD status;
+
+    CLEAR(start_info);
+    CLEAR(proc_info);
+    CLEAR(self_exe);
+
+    status = GetModuleFileName(NULL, self_exe, sizeof(self_exe));
+    if (status == 0 || status == sizeof(self_exe))
+    {
+        msg(M_WARN|M_ERRNO, "fork_to_self: CreateProcess failed: cannot get module name via GetModuleFileName");
+        goto done;
+    }
+
+    /* fill in STARTUPINFO struct */
+    GetStartupInfo(&start_info);
+    start_info.cb = sizeof(start_info);
+    start_info.dwFlags = STARTF_USESHOWWINDOW;
+    start_info.wShowWindow = SW_HIDE;
+
+    if (CreateProcess(self_exe, cl, NULL, NULL, FALSE, 0, NULL, NULL, &start_info, &proc_info))
+    {
+        CloseHandle(proc_info.hThread);
+        CloseHandle(proc_info.hProcess);
+    }
+    else
+    {
+        msg(M_WARN|M_ERRNO, "fork_to_self: CreateProcess failed: %s", cmdline);
+    }
+
+done:
+    free(cl);
+}
+
+char *
+get_win_sys_path(void)
+{
+    ASSERT(win_sys_path);
+    return win_sys_path;
+}
+
+void
+set_win_sys_path(const char *newpath, struct env_set *es)
+{
+    free(win_sys_path);
+    win_sys_path = string_alloc(newpath, NULL);
+    setenv_str(es, SYS_PATH_ENV_VAR_NAME, win_sys_path); /* route.exe needs this */
+}
+
+void
+set_win_sys_path_via_env(struct env_set *es)
+{
+    char buf[256];
+    DWORD status = GetEnvironmentVariable(SYS_PATH_ENV_VAR_NAME, buf, sizeof(buf));
+    if (!status)
+    {
+        msg(M_ERR, "Cannot find environmental variable %s", SYS_PATH_ENV_VAR_NAME);
+    }
+    if (status > sizeof(buf) - 1)
+    {
+        msg(M_FATAL, "String overflow attempting to read environmental variable %s", SYS_PATH_ENV_VAR_NAME);
+    }
+    set_win_sys_path(buf, es);
+}
+
+
+const char *
+win_get_tempdir(void)
+{
+    static char tmpdir[MAX_PATH];
+    WCHAR wtmpdir[MAX_PATH];
+
+    if (!GetTempPathW(_countof(wtmpdir), wtmpdir))
+    {
+        /* Warn if we can't find a valid temporary directory, which should
+         * be unlikely.
+         */
+        msg(M_WARN, "Could not find a suitable temporary directory."
+            " (GetTempPath() failed).  Consider using --tmp-dir");
+        return NULL;
+    }
+
+    if (WideCharToMultiByte(CP_UTF8, 0, wtmpdir, -1, NULL, 0, NULL, NULL) > sizeof(tmpdir))
+    {
+        msg(M_WARN, "Could not get temporary directory. Path is too long."
+            "  Consider using --tmp-dir");
+        return NULL;
+    }
+
+    WideCharToMultiByte(CP_UTF8, 0, wtmpdir, -1, tmpdir, sizeof(tmpdir), NULL, NULL);
+    return tmpdir;
+}
+
+static bool
+win_block_dns_service(bool add, int index, const HANDLE pipe)
+{
+    DWORD len;
+    bool ret = false;
+    ack_message_t ack;
+    struct gc_arena gc = gc_new();
+
+    block_dns_message_t data = {
+        .header = {
+            (add ? msg_add_block_dns : msg_del_block_dns),
+            sizeof(block_dns_message_t),
+            0
+        },
+        .iface = { .index = index, .name = "" }
+    };
+
+    if (!WriteFile(pipe, &data, sizeof(data), &len, NULL)
+        || !ReadFile(pipe, &ack, sizeof(ack), &len, NULL))
+    {
+        msg(M_WARN, "Block_DNS: could not talk to service: %s [%lu]",
+            strerror_win32(GetLastError(), &gc), GetLastError());
+        goto out;
+    }
+
+    if (ack.error_number != NO_ERROR)
+    {
+        msg(M_WARN, "Block_DNS: %s block dns filters using service failed: %s [status=0x%x if_index=%d]",
+            (add ? "adding" : "deleting"), strerror_win32(ack.error_number, &gc),
+            ack.error_number, data.iface.index);
+        goto out;
+    }
+
+    ret = true;
+    msg(M_INFO, "%s outside dns using service succeeded.", (add ? "Blocking" : "Unblocking"));
+out:
+    gc_free(&gc);
+    return ret;
+}
+
+static void
+block_dns_msg_handler(DWORD err, const char *msg)
+{
+    struct gc_arena gc = gc_new();
+
+    if (err == 0)
+    {
+        msg(M_INFO, "%s", msg);
+    }
+    else
+    {
+        msg(M_WARN, "Error in add_block_dns_filters(): %s : %s [status=0x%lx]",
+            msg, strerror_win32(err, &gc), err);
+    }
+
+    gc_free(&gc);
+}
+
+bool
+win_wfp_block_dns(const NET_IFINDEX index, const HANDLE msg_channel)
+{
+    WCHAR openvpnpath[MAX_PATH];
+    bool ret = false;
+    DWORD status;
+
+    if (msg_channel)
+    {
+        dmsg(D_LOW, "Using service to add block dns filters");
+        ret = win_block_dns_service(true, index, msg_channel);
+        goto out;
+    }
+
+    status = GetModuleFileNameW(NULL, openvpnpath, _countof(openvpnpath));
+    if (status == 0 || status == _countof(openvpnpath))
+    {
+        msg(M_WARN|M_ERRNO, "block_dns: cannot get executable path");
+        goto out;
+    }
+
+    status = add_block_dns_filters(&m_hEngineHandle, index, openvpnpath,
+                                   block_dns_msg_handler);
+    if (status == 0)
+    {
+        int is_auto = 0;
+        tap_metric_v4 = get_interface_metric(index, AF_INET, &is_auto);
+        if (is_auto)
+        {
+            tap_metric_v4 = 0;
+        }
+        tap_metric_v6 = get_interface_metric(index, AF_INET6, &is_auto);
+        if (is_auto)
+        {
+            tap_metric_v6 = 0;
+        }
+        status = set_interface_metric(index, AF_INET, BLOCK_DNS_IFACE_METRIC);
+        if (!status)
+        {
+            set_interface_metric(index, AF_INET6, BLOCK_DNS_IFACE_METRIC);
+        }
+    }
+
+    ret = (status == 0);
+
+out:
+
+    return ret;
+}
+
+bool
+win_wfp_uninit(const NET_IFINDEX index, const HANDLE msg_channel)
+{
+    dmsg(D_LOW, "Uninitializing WFP");
+
+    if (msg_channel)
+    {
+        msg(D_LOW, "Using service to delete block dns filters");
+        win_block_dns_service(false, index, msg_channel);
+    }
+    else
+    {
+        delete_block_dns_filters(m_hEngineHandle);
+        m_hEngineHandle = NULL;
+        if (tap_metric_v4 >= 0)
+        {
+            set_interface_metric(index, AF_INET, tap_metric_v4);
+        }
+        if (tap_metric_v6 >= 0)
+        {
+            set_interface_metric(index, AF_INET6, tap_metric_v6);
+        }
+    }
+
+    return true;
+}
+
+int
+win32_version_info(void)
+{
+    if (!IsWindowsXPOrGreater())
+    {
+        msg(M_FATAL, "Error: Windows version must be XP or greater.");
+    }
+
+    if (!IsWindowsVistaOrGreater())
+    {
+        return WIN_XP;
+    }
+
+    if (!IsWindows7OrGreater())
+    {
+        return WIN_VISTA;
+    }
+
+    if (!IsWindows8OrGreater())
+    {
+        return WIN_7;
+    }
+    else
+    {
+        return WIN_8;
+    }
+}
+
+bool
+win32_is_64bit(void)
+{
+#if defined(_WIN64)
+    return true;  /* 64-bit programs run only on Win64 */
+#elif defined(_WIN32)
+    /* 32-bit programs run on both 32-bit and 64-bit Windows */
+    BOOL f64 = FALSE;
+    return IsWow64Process(GetCurrentProcess(), &f64) && f64;
+#else  /* if defined(_WIN64) */
+    return false; /* Win64 does not support Win16 */
+#endif
+}
+
+const char *
+win32_version_string(struct gc_arena *gc, bool add_name)
+{
+    int version = win32_version_info();
+    struct buffer out = alloc_buf_gc(256, gc);
+
+    switch (version)
+    {
+        case WIN_XP:
+            buf_printf(&out, "5.1%s", add_name ? " (Windows XP)" : "");
+            break;
+
+        case WIN_VISTA:
+            buf_printf(&out, "6.0%s", add_name ? " (Windows Vista)" : "");
+            break;
+
+        case WIN_7:
+            buf_printf(&out, "6.1%s", add_name ? " (Windows 7)" : "");
+            break;
+
+        case WIN_8:
+            buf_printf(&out, "6.2%s", add_name ? " (Windows 8 or greater)" : "");
+            break;
+
+        default:
+            msg(M_NONFATAL, "Unknown Windows version: %d", version);
+            buf_printf(&out, "0.0%s", add_name ? " (unknown)" : "");
+            break;
+    }
+
+    buf_printf(&out, win32_is_64bit() ? " 64bit" : " 32bit");
+
+    return (const char *)out.data;
+}
+
+#endif /* ifdef _WIN32 */
diff --git a/src/openvpn/win32.h b/src/openvpn/win32.h
new file mode 100644
index 0000000..4b99a5e
--- /dev/null
+++ b/src/openvpn/win32.h
@@ -0,0 +1,311 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifdef _WIN32
+#ifndef OPENVPN_WIN32_H
+#define OPENVPN_WIN32_H
+
+#include "mtu.h"
+
+/* location of executables */
+#define SYS_PATH_ENV_VAR_NAME "SystemRoot"  /* environmental variable name that normally contains the system path */
+#define NETSH_PATH_SUFFIX     "\\system32\\netsh.exe"
+#define WIN_ROUTE_PATH_SUFFIX "\\system32\\route.exe"
+#define WIN_IPCONFIG_PATH_SUFFIX "\\system32\\ipconfig.exe"
+#define WIN_NET_PATH_SUFFIX "\\system32\\net.exe"
+
+/*
+ * Win32-specific OpenVPN code, targetted at the mingw
+ * development environment.
+ */
+
+/* MSVC headers do not define this macro, so do it here */
+#ifndef IN6_ARE_ADDR_EQUAL
+#define IN6_ARE_ADDR_EQUAL(a,b) \
+    (memcmp((const void *)(a), (const void *)(b), sizeof(struct in6_addr)) == 0)
+#endif
+
+void init_win32(void);
+
+void uninit_win32(void);
+
+void set_pause_exit_win32(void);
+
+struct security_attributes
+{
+    SECURITY_ATTRIBUTES sa;
+    SECURITY_DESCRIPTOR sd;
+};
+
+#define HANDLE_DEFINED(h) ((h) != NULL && (h) != INVALID_HANDLE_VALUE)
+
+/*
+ * Save old window title.
+ */
+struct window_title
+{
+    bool saved;
+    char old_window_title [256];
+};
+
+struct rw_handle {
+    HANDLE read;
+    HANDLE write;
+};
+
+/*
+ * Event-based notification of incoming TCP connections
+ */
+
+#define NE32_PERSIST_EVENT (1<<0)
+#define NE32_WRITE_EVENT   (1<<1)
+
+static inline bool
+defined_net_event_win32(const struct rw_handle *event)
+{
+    return event->read != NULL;
+}
+
+void init_net_event_win32(struct rw_handle *event, long network_events, socket_descriptor_t sd, unsigned int flags);
+
+long reset_net_event_win32(struct rw_handle *event, socket_descriptor_t sd);
+
+void close_net_event_win32(struct rw_handle *event, socket_descriptor_t sd, unsigned int flags);
+
+/*
+ * A stateful variant of the net_event_win32 functions above
+ */
+
+struct net_event_win32
+{
+    struct rw_handle handle;
+    socket_descriptor_t sd;
+    long event_mask;
+};
+
+void net_event_win32_init(struct net_event_win32 *ne);
+
+void net_event_win32_start(struct net_event_win32 *ne, long network_events, socket_descriptor_t sd);
+
+void net_event_win32_reset(struct net_event_win32 *ne);
+
+void net_event_win32_reset_write(struct net_event_win32 *ne);
+
+void net_event_win32_stop(struct net_event_win32 *ne);
+
+void net_event_win32_close(struct net_event_win32 *ne);
+
+static inline bool
+net_event_win32_defined(const struct net_event_win32 *ne)
+{
+    return defined_net_event_win32(&ne->handle);
+}
+
+static inline struct rw_handle *
+net_event_win32_get_event(struct net_event_win32 *ne)
+{
+    return &ne->handle;
+}
+
+static inline long
+net_event_win32_get_event_mask(const struct net_event_win32 *ne)
+{
+    return ne->event_mask;
+}
+
+static inline void
+net_event_win32_clear_selected_events(struct net_event_win32 *ne, long selected_events)
+{
+    ne->event_mask &= ~selected_events;
+}
+
+/*
+ * Signal handling
+ */
+struct win32_signal {
+#define WSO_MODE_UNDEF   0
+#define WSO_MODE_SERVICE 1
+#define WSO_MODE_CONSOLE 2
+    int mode;
+    struct rw_handle in;
+    DWORD console_mode_save;
+    bool console_mode_save_defined;
+};
+
+extern struct win32_signal win32_signal; /* static/global */
+extern struct window_title window_title; /* static/global */
+
+void win32_signal_clear(struct win32_signal *ws);
+
+/* win32_signal_open startup type */
+#define WSO_NOFORCE       0
+#define WSO_FORCE_SERVICE 1
+#define WSO_FORCE_CONSOLE 2
+
+void win32_signal_open(struct win32_signal *ws,
+                       int force,  /* set to WSO force parm */
+                       const char *exit_event_name,
+                       bool exit_event_initial_state);
+
+void win32_signal_close(struct win32_signal *ws);
+
+int win32_signal_get(struct win32_signal *ws);
+
+void win32_pause(struct win32_signal *ws);
+
+bool win32_service_interrupt(struct win32_signal *ws);
+
+/*
+ * Set the text on the window title bar
+ */
+
+void window_title_clear(struct window_title *wt);
+
+void window_title_save(struct window_title *wt);
+
+void window_title_restore(const struct window_title *wt);
+
+void window_title_generate(const char *title);
+
+/*
+ * We try to do all Win32 I/O using overlapped
+ * (i.e. asynchronous) I/O for a performance win.
+ */
+struct overlapped_io {
+#define IOSTATE_INITIAL          0
+#define IOSTATE_QUEUED           1  /* overlapped I/O has been queued */
+#define IOSTATE_IMMEDIATE_RETURN 2  /* I/O function returned immediately without queueing */
+    int iostate;
+    OVERLAPPED overlapped;
+    DWORD size;
+    DWORD flags;
+    int status;
+    bool addr_defined;
+    union {
+        struct sockaddr_in addr;
+        struct sockaddr_in6 addr6;
+    };
+    int addrlen;
+    struct buffer buf_init;
+    struct buffer buf;
+};
+
+void overlapped_io_init(struct overlapped_io *o,
+                        const struct frame *frame,
+                        BOOL event_state,
+                        bool tuntap_buffer);
+
+void overlapped_io_close(struct overlapped_io *o);
+
+static inline bool
+overlapped_io_active(struct overlapped_io *o)
+{
+    return o->iostate == IOSTATE_QUEUED || o->iostate == IOSTATE_IMMEDIATE_RETURN;
+}
+
+char *overlapped_io_state_ascii(const struct overlapped_io *o);
+
+/*
+ * Use to control access to resources that only one
+ * OpenVPN process on a given machine can access at
+ * a given time.
+ */
+
+struct semaphore
+{
+    const char *name;
+    bool locked;
+    HANDLE hand;
+};
+
+void semaphore_clear(struct semaphore *s);
+
+void semaphore_open(struct semaphore *s, const char *name);
+
+bool semaphore_lock(struct semaphore *s, int timeout_milliseconds);
+
+void semaphore_release(struct semaphore *s);
+
+void semaphore_close(struct semaphore *s);
+
+/*
+ * Special global semaphore used to protect network
+ * shell commands from simultaneous instantiation.
+ *
+ * It seems you can't run more than one instance
+ * of netsh on the same machine at the same time.
+ */
+
+extern struct semaphore netcmd_semaphore;
+void netcmd_semaphore_init(void);
+
+void netcmd_semaphore_close(void);
+
+void netcmd_semaphore_lock(void);
+
+void netcmd_semaphore_release(void);
+
+/* Set Win32 security attributes structure to allow all access */
+bool init_security_attributes_allow_all(struct security_attributes *obj);
+
+/* return true if filename is safe to be used on Windows */
+bool win_safe_filename(const char *fn);
+
+/* add constant environmental variables needed by Windows */
+struct env_set;
+
+/* get and set the current windows system path */
+void set_win_sys_path(const char *newpath, struct env_set *es);
+
+void set_win_sys_path_via_env(struct env_set *es);
+
+char *get_win_sys_path(void);
+
+/* call self in a subprocess */
+void fork_to_self(const char *cmdline);
+
+/* Find temporary directory */
+const char *win_get_tempdir(void);
+
+/* Convert a string from UTF-8 to UCS-2 */
+WCHAR *wide_string(const char *utf8, struct gc_arena *gc);
+
+bool win_wfp_block_dns(const NET_IFINDEX index, const HANDLE msg_channel);
+
+bool win_wfp_uninit(const NET_IFINDEX index, const HANDLE msg_channel);
+
+#define WIN_XP 0
+#define WIN_VISTA 1
+#define WIN_7 2
+#define WIN_8 3
+
+int win32_version_info(void);
+
+/*
+ * String representation of Windows version number and name, see
+ * https://msdn.microsoft.com/en-us/library/windows/desktop/ms724832(v=vs.85).aspx
+ */
+const char *win32_version_string(struct gc_arena *gc, bool add_name);
+
+#endif /* ifndef OPENVPN_WIN32_H */
+#endif /* ifdef _WIN32 */
diff --git a/src/openvpnserv/Makefile.am b/src/openvpnserv/Makefile.am
new file mode 100644
index 0000000..bc65070
--- /dev/null
+++ b/src/openvpnserv/Makefile.am
@@ -0,0 +1,39 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+include $(top_srcdir)/build/ltrc.inc
+
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+EXTRA_DIST = \
+	openvpnserv.vcxproj \
+	openvpnserv.vcxproj.filters
+
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/include -I$(top_srcdir)/src/openvpn -I$(top_srcdir)/src/compat
+
+if WIN32
+sbin_PROGRAMS = openvpnserv
+openvpnserv_CFLAGS = \
+	-municode -D_UNICODE \
+	-UNTDDI_VERSION -U_WIN32_WINNT \
+	-D_WIN32_WINNT=_WIN32_WINNT_VISTA
+openvpnserv_LDADD = -ladvapi32 -luserenv -liphlpapi -lfwpuclnt -lrpcrt4 -lshlwapi -lnetapi32 -lws2_32 -lntdll
+endif
+
+openvpnserv_SOURCES = \
+        common.c \
+	automatic.c \
+	interactive.c \
+	service.c service.h \
+	validate.c validate.h \
+	$(top_srcdir)/src/openvpn/block_dns.c $(top_srcdir)/src/openvpn/block_dns.h \
+	openvpnserv_resources.rc
diff --git a/src/openvpnserv/automatic.c b/src/openvpnserv/automatic.c
new file mode 100644
index 0000000..5569ce9
--- /dev/null
+++ b/src/openvpnserv/automatic.c
@@ -0,0 +1,443 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * This program allows one or more OpenVPN processes to be started
+ * as a service.  To build, you must get the service sample from the
+ * Platform SDK and replace Simple.c with this file.
+ *
+ * You should also apply service.patch to
+ * service.c and service.h from the Platform SDK service sample.
+ *
+ * This code is designed to be built with the mingw compiler.
+ */
+
+#include "service.h"
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <process.h>
+
+/* bool definitions */
+#define bool int
+#define true 1
+#define false 0
+
+static SERVICE_STATUS_HANDLE service;
+static SERVICE_STATUS status = { .dwServiceType = SERVICE_WIN32_SHARE_PROCESS };
+
+openvpn_service_t automatic_service = {
+    automatic,
+    TEXT(PACKAGE_NAME "ServiceLegacy"),
+    TEXT(PACKAGE_NAME " Legacy Service"),
+    TEXT(SERVICE_DEPENDENCIES),
+    SERVICE_DEMAND_START
+};
+
+struct security_attributes
+{
+    SECURITY_ATTRIBUTES sa;
+    SECURITY_DESCRIPTOR sd;
+};
+
+static HANDLE exit_event = NULL;
+
+/* clear an object */
+#define CLEAR(x) memset(&(x), 0, sizeof(x))
+
+
+bool
+init_security_attributes_allow_all(struct security_attributes *obj)
+{
+    CLEAR(*obj);
+
+    obj->sa.nLength = sizeof(SECURITY_ATTRIBUTES);
+    obj->sa.lpSecurityDescriptor = &obj->sd;
+    obj->sa.bInheritHandle = TRUE;
+    if (!InitializeSecurityDescriptor(&obj->sd, SECURITY_DESCRIPTOR_REVISION))
+    {
+        return false;
+    }
+    if (!SetSecurityDescriptorDacl(&obj->sd, TRUE, NULL, FALSE))
+    {
+        return false;
+    }
+    return true;
+}
+
+HANDLE
+create_event(LPCTSTR name, bool allow_all, bool initial_state, bool manual_reset)
+{
+    if (allow_all)
+    {
+        struct security_attributes sa;
+        if (!init_security_attributes_allow_all(&sa))
+        {
+            return NULL;
+        }
+        return CreateEvent(&sa.sa, (BOOL)manual_reset, (BOOL)initial_state, name);
+    }
+    else
+    {
+        return CreateEvent(NULL, (BOOL)manual_reset, (BOOL)initial_state, name);
+    }
+}
+
+void
+close_if_open(HANDLE h)
+{
+    if (h != NULL)
+    {
+        CloseHandle(h);
+    }
+}
+
+static bool
+match(const WIN32_FIND_DATA *find, LPCTSTR ext)
+{
+    int i;
+
+    if (find->dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY)
+    {
+        return false;
+    }
+
+    if (!_tcslen(ext))
+    {
+        return true;
+    }
+
+    i = _tcslen(find->cFileName) - _tcslen(ext) - 1;
+    if (i < 1)
+    {
+        return false;
+    }
+
+    return find->cFileName[i] == '.' && !_tcsicmp(find->cFileName + i + 1, ext);
+}
+
+/*
+ * Modify the extension on a filename.
+ */
+static bool
+modext(LPTSTR dest, int size, LPCTSTR src, LPCTSTR newext)
+{
+    int i;
+
+    if (size > 0 && (_tcslen(src) + 1) <= size)
+    {
+        _tcscpy(dest, src);
+        dest [size - 1] = TEXT('\0');
+        i = _tcslen(dest);
+        while (--i >= 0)
+        {
+            if (dest[i] == TEXT('\\'))
+            {
+                break;
+            }
+            if (dest[i] == TEXT('.'))
+            {
+                dest[i] = TEXT('\0');
+                break;
+            }
+        }
+        if (_tcslen(dest) + _tcslen(newext) + 2 <= size)
+        {
+            _tcscat(dest, TEXT("."));
+            _tcscat(dest, newext);
+            return true;
+        }
+        dest[0] = TEXT('\0');
+    }
+    return false;
+}
+
+static DWORD WINAPI
+ServiceCtrlAutomatic(DWORD ctrl_code, DWORD event, LPVOID data, LPVOID ctx)
+{
+    SERVICE_STATUS *status = ctx;
+    switch (ctrl_code)
+    {
+        case SERVICE_CONTROL_STOP:
+            status->dwCurrentState = SERVICE_STOP_PENDING;
+            ReportStatusToSCMgr(service, status);
+            if (exit_event)
+            {
+                SetEvent(exit_event);
+            }
+            return NO_ERROR;
+
+        case SERVICE_CONTROL_INTERROGATE:
+            return NO_ERROR;
+
+        default:
+            return ERROR_CALL_NOT_IMPLEMENTED;
+    }
+}
+
+
+VOID WINAPI
+ServiceStartAutomaticOwn(DWORD dwArgc, LPTSTR *lpszArgv)
+{
+    status.dwServiceType = SERVICE_WIN32_OWN_PROCESS;
+    ServiceStartAutomatic(dwArgc, lpszArgv);
+}
+
+
+VOID WINAPI
+ServiceStartAutomatic(DWORD dwArgc, LPTSTR *lpszArgv)
+{
+    DWORD error = NO_ERROR;
+    settings_t settings;
+    TCHAR event_name[256];
+
+    service = RegisterServiceCtrlHandlerEx(automatic_service.name, ServiceCtrlAutomatic, &status);
+    if (!service)
+    {
+        return;
+    }
+
+    status.dwCurrentState = SERVICE_START_PENDING;
+    status.dwServiceSpecificExitCode = NO_ERROR;
+    status.dwWin32ExitCode = NO_ERROR;
+    status.dwWaitHint = 3000;
+
+    if (!ReportStatusToSCMgr(service, &status))
+    {
+        MsgToEventLog(M_ERR, TEXT("ReportStatusToSCMgr #1 failed"));
+        goto finish;
+    }
+
+    /*
+     * Create our exit event
+     * This event is initially created in the non-signaled
+     * state.  It will transition to the signaled state when
+     * we have received a terminate signal from the Service
+     * Control Manager which will cause an asynchronous call
+     * of ServiceStop below.
+     */
+
+    openvpn_sntprintf(event_name, _countof(event_name), TEXT(PACKAGE "%s_exit_1"), service_instance);
+    exit_event = create_event(event_name, false, false, true);
+    if (!exit_event)
+    {
+        MsgToEventLog(M_ERR, TEXT("CreateEvent failed"));
+        goto finish;
+    }
+
+    /*
+     * If exit event is already signaled, it means we were not
+     * shut down properly.
+     */
+    if (WaitForSingleObject(exit_event, 0) != WAIT_TIMEOUT)
+    {
+        MsgToEventLog(M_ERR, TEXT("Exit event is already signaled -- we were not shut down properly"));
+        goto finish;
+    }
+
+    if (!ReportStatusToSCMgr(service, &status))
+    {
+        MsgToEventLog(M_ERR, TEXT("ReportStatusToSCMgr #2 failed"));
+        goto finish;
+    }
+
+    /*
+     * Read info from registry in key HKLM\SOFTWARE\OpenVPN
+     */
+    error = GetOpenvpnSettings(&settings);
+    if (error != ERROR_SUCCESS)
+    {
+        goto finish;
+    }
+
+    /*
+     * Instantiate an OpenVPN process for each configuration
+     * file found.
+     */
+    {
+        WIN32_FIND_DATA find_obj;
+        HANDLE find_handle;
+        BOOL more_files;
+        TCHAR find_string[MAX_PATH];
+
+        openvpn_sntprintf(find_string, MAX_PATH, TEXT("%s\\*"), settings.config_dir);
+
+        find_handle = FindFirstFile(find_string, &find_obj);
+        if (find_handle == INVALID_HANDLE_VALUE)
+        {
+            MsgToEventLog(M_ERR, TEXT("Cannot get configuration file list using: %s"), find_string);
+            goto finish;
+        }
+
+        /*
+         * Loop over each config file
+         */
+        do
+        {
+            HANDLE log_handle = NULL;
+            STARTUPINFO start_info;
+            PROCESS_INFORMATION proc_info;
+            struct security_attributes sa;
+            TCHAR log_file[MAX_PATH];
+            TCHAR log_path[MAX_PATH];
+            TCHAR command_line[256];
+
+            CLEAR(start_info);
+            CLEAR(proc_info);
+            CLEAR(sa);
+
+            if (!ReportStatusToSCMgr(service, &status))
+            {
+                MsgToEventLog(M_ERR, TEXT("ReportStatusToSCMgr #3 failed"));
+                FindClose(find_handle);
+                goto finish;
+            }
+
+            /* does file have the correct type and extension? */
+            if (match(&find_obj, settings.ext_string))
+            {
+                /* get log file pathname */
+                if (!modext(log_file, _countof(log_file), find_obj.cFileName, TEXT("log")))
+                {
+                    MsgToEventLog(M_ERR, TEXT("Cannot construct logfile name based on: %s"), find_obj.cFileName);
+                    FindClose(find_handle);
+                    goto finish;
+                }
+                openvpn_sntprintf(log_path, _countof(log_path),
+                                  TEXT("%s\\%s"), settings.log_dir, log_file);
+
+                /* construct command line */
+                openvpn_sntprintf(command_line, _countof(command_line), TEXT("openvpn --service \"" PACKAGE "%s_exit_1\" 1 --config \"%s\""),
+                                  service_instance,
+                                  find_obj.cFileName);
+
+                /* Make security attributes struct for logfile handle so it can
+                 * be inherited. */
+                if (!init_security_attributes_allow_all(&sa))
+                {
+                    error = MsgToEventLog(M_SYSERR, TEXT("InitializeSecurityDescriptor start_" PACKAGE " failed"));
+                    goto finish;
+                }
+
+                /* open logfile as stdout/stderr for soon-to-be-spawned subprocess */
+                log_handle = CreateFile(log_path,
+                                        GENERIC_WRITE,
+                                        FILE_SHARE_READ,
+                                        &sa.sa,
+                                        settings.append ? OPEN_ALWAYS : CREATE_ALWAYS,
+                                        FILE_ATTRIBUTE_NORMAL,
+                                        NULL);
+
+                if (log_handle == INVALID_HANDLE_VALUE)
+                {
+                    error = MsgToEventLog(M_SYSERR, TEXT("Cannot open logfile: %s"), log_path);
+                    FindClose(find_handle);
+                    goto finish;
+                }
+
+                /* append to logfile? */
+                if (settings.append)
+                {
+                    if (SetFilePointer(log_handle, 0, NULL, FILE_END) == INVALID_SET_FILE_POINTER)
+                    {
+                        error = MsgToEventLog(M_SYSERR, TEXT("Cannot seek to end of logfile: %s"), log_path);
+                        FindClose(find_handle);
+                        goto finish;
+                    }
+                }
+
+                /* fill in STARTUPINFO struct */
+                GetStartupInfo(&start_info);
+                start_info.cb = sizeof(start_info);
+                start_info.dwFlags = STARTF_USESTDHANDLES|STARTF_USESHOWWINDOW;
+                start_info.wShowWindow = SW_HIDE;
+                start_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
+                start_info.hStdOutput = start_info.hStdError = log_handle;
+
+                /* create an OpenVPN process for one config file */
+                if (!CreateProcess(settings.exe_path,
+                                   command_line,
+                                   NULL,
+                                   NULL,
+                                   TRUE,
+                                   settings.priority | CREATE_NEW_CONSOLE,
+                                   NULL,
+                                   settings.config_dir,
+                                   &start_info,
+                                   &proc_info))
+                {
+                    error = MsgToEventLog(M_SYSERR, TEXT("CreateProcess failed, exe='%s' cmdline='%s' dir='%s'"),
+                                          settings.exe_path,
+                                          command_line,
+                                          settings.config_dir);
+
+                    FindClose(find_handle);
+                    CloseHandle(log_handle);
+                    goto finish;
+                }
+
+                /* close unneeded handles */
+                Sleep(1000); /* try to prevent race if we close logfile
+                              * handle before child process DUPs it */
+                if (!CloseHandle(proc_info.hProcess)
+                    || !CloseHandle(proc_info.hThread)
+                    || !CloseHandle(log_handle))
+                {
+                    error = MsgToEventLog(M_SYSERR, TEXT("CloseHandle failed"));
+                    goto finish;
+                }
+            }
+
+            /* more files to process? */
+            more_files = FindNextFile(find_handle, &find_obj);
+
+        } while (more_files);
+
+        FindClose(find_handle);
+    }
+
+    /* we are now fully started */
+    status.dwCurrentState = SERVICE_RUNNING;
+    status.dwWaitHint = 0;
+    if (!ReportStatusToSCMgr(service, &status))
+    {
+        MsgToEventLog(M_ERR, TEXT("ReportStatusToSCMgr SERVICE_RUNNING failed"));
+        goto finish;
+    }
+
+    /* wait for our shutdown signal */
+    if (WaitForSingleObject(exit_event, INFINITE) != WAIT_OBJECT_0)
+    {
+        MsgToEventLog(M_ERR, TEXT("wait for shutdown signal failed"));
+    }
+
+finish:
+    if (exit_event)
+    {
+        CloseHandle(exit_event);
+    }
+
+    status.dwCurrentState = SERVICE_STOPPED;
+    status.dwWin32ExitCode = error;
+    ReportStatusToSCMgr(service, &status);
+}
diff --git a/src/openvpnserv/common.c b/src/openvpnserv/common.c
new file mode 100644
index 0000000..eb718d4
--- /dev/null
+++ b/src/openvpnserv/common.c
@@ -0,0 +1,303 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2011-2018 Heiko Hund <heiko.hund@sophos.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "service.h"
+#include "validate.h"
+
+LPCTSTR service_instance = TEXT("");
+static wchar_t win_sys_path[MAX_PATH];
+
+/*
+ * These are necessary due to certain buggy implementations of (v)snprintf,
+ * that don't guarantee null termination for size > 0.
+ */
+int
+openvpn_vsntprintf(LPTSTR str, size_t size, LPCTSTR format, va_list arglist)
+{
+    int len = -1;
+    if (size > 0)
+    {
+        len = _vsntprintf(str, size, format, arglist);
+        str[size - 1] = 0;
+    }
+    return (len >= 0 && len < size);
+}
+int
+openvpn_sntprintf(LPTSTR str, size_t size, LPCTSTR format, ...)
+{
+    va_list arglist;
+    int len = -1;
+    if (size > 0)
+    {
+        va_start(arglist, format);
+        len = openvpn_vsntprintf(str, size, format, arglist);
+        va_end(arglist);
+    }
+    return len;
+}
+
+static DWORD
+GetRegString(HKEY key, LPCTSTR value, LPTSTR data, DWORD size, LPCTSTR default_value)
+{
+    LONG status = RegGetValue(key, NULL, value, RRF_RT_REG_SZ,
+                              NULL, (LPBYTE) data, &size);
+
+    if (status == ERROR_FILE_NOT_FOUND && default_value)
+    {
+        size_t len = size/sizeof(data[0]);
+        if (openvpn_sntprintf(data, len, default_value) > 0)
+        {
+            status = ERROR_SUCCESS;
+        }
+    }
+
+    if (status != ERROR_SUCCESS)
+    {
+        SetLastError(status);
+        return MsgToEventLog(M_SYSERR, TEXT("Error querying registry value: HKLM\\SOFTWARE\\" PACKAGE_NAME "%s\\%s"), service_instance, value);
+    }
+
+    return ERROR_SUCCESS;
+}
+
+
+DWORD
+GetOpenvpnSettings(settings_t *s)
+{
+    TCHAR reg_path[256];
+    TCHAR priority[64];
+    TCHAR append[2];
+    DWORD error;
+    HKEY key;
+    TCHAR install_path[MAX_PATH];
+    TCHAR default_value[MAX_PATH];
+
+    openvpn_sntprintf(reg_path, _countof(reg_path), TEXT("SOFTWARE\\" PACKAGE_NAME "%s"), service_instance);
+
+    LONG status = RegOpenKeyEx(HKEY_LOCAL_MACHINE, reg_path, 0, KEY_READ, &key);
+    if (status != ERROR_SUCCESS)
+    {
+        SetLastError(status);
+        return MsgToEventLog(M_SYSERR, TEXT("Could not open Registry key HKLM\\%s not found"), reg_path);
+    }
+
+    /* The default value of REG_KEY is the install path */
+    status = GetRegString(key, NULL, install_path, sizeof(install_path), NULL);
+    if (status != ERROR_SUCCESS)
+    {
+        error = status;
+        goto out;
+    }
+
+    openvpn_sntprintf(default_value, _countof(default_value), TEXT("%s\\bin\\openvpn.exe"),
+                      install_path);
+    error = GetRegString(key, TEXT("exe_path"), s->exe_path, sizeof(s->exe_path), default_value);
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    openvpn_sntprintf(default_value, _countof(default_value), TEXT("%s\\config"), install_path);
+    error = GetRegString(key, TEXT("config_dir"), s->config_dir, sizeof(s->config_dir),
+                         default_value);
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    error = GetRegString(key, TEXT("config_ext"), s->ext_string, sizeof(s->ext_string),
+                         TEXT(".ovpn"));
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    openvpn_sntprintf(default_value, _countof(default_value), TEXT("%s\\log"), install_path);
+    error = GetRegString(key, TEXT("log_dir"), s->log_dir, sizeof(s->log_dir), default_value);
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    error = GetRegString(key, TEXT("priority"), priority, sizeof(priority),
+                         TEXT("NORMAL_PRIORITY_CLASS"));
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    error = GetRegString(key, TEXT("log_append"), append, sizeof(append), TEXT("0"));
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    /* read if present, else use default */
+    error = GetRegString(key, TEXT("ovpn_admin_group"), s->ovpn_admin_group,
+                         sizeof(s->ovpn_admin_group), OVPN_ADMIN_GROUP);
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+    /* set process priority */
+    if (!_tcsicmp(priority, TEXT("IDLE_PRIORITY_CLASS")))
+    {
+        s->priority = IDLE_PRIORITY_CLASS;
+    }
+    else if (!_tcsicmp(priority, TEXT("BELOW_NORMAL_PRIORITY_CLASS")))
+    {
+        s->priority = BELOW_NORMAL_PRIORITY_CLASS;
+    }
+    else if (!_tcsicmp(priority, TEXT("NORMAL_PRIORITY_CLASS")))
+    {
+        s->priority = NORMAL_PRIORITY_CLASS;
+    }
+    else if (!_tcsicmp(priority, TEXT("ABOVE_NORMAL_PRIORITY_CLASS")))
+    {
+        s->priority = ABOVE_NORMAL_PRIORITY_CLASS;
+    }
+    else if (!_tcsicmp(priority, TEXT("HIGH_PRIORITY_CLASS")))
+    {
+        s->priority = HIGH_PRIORITY_CLASS;
+    }
+    else
+    {
+        SetLastError(ERROR_INVALID_DATA);
+        error = MsgToEventLog(M_SYSERR, TEXT("Unknown priority name: %s"), priority);
+        goto out;
+    }
+
+    /* set log file append/truncate flag */
+    if (append[0] == TEXT('0'))
+    {
+        s->append = FALSE;
+    }
+    else if (append[0] == TEXT('1'))
+    {
+        s->append = TRUE;
+    }
+    else
+    {
+        SetLastError(ERROR_INVALID_DATA);
+        error = MsgToEventLog(M_ERR, TEXT("Log file append flag (given as '%s') must be '0' or '1'"), append);
+        goto out;
+    }
+
+out:
+    RegCloseKey(key);
+    return error;
+}
+
+
+LPCTSTR
+GetLastErrorText()
+{
+    static TCHAR buf[256];
+    DWORD len;
+    LPTSTR tmp = NULL;
+
+    len = FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ARGUMENT_ARRAY,
+                        NULL, GetLastError(), LANG_NEUTRAL, (LPTSTR)&tmp, 0, NULL);
+
+    if (len == 0 || (long) _countof(buf) < (long) len + 14)
+    {
+        buf[0] = TEXT('\0');
+    }
+    else
+    {
+        tmp[_tcslen(tmp) - 2] = TEXT('\0'); /* remove CR/LF characters */
+        openvpn_sntprintf(buf, _countof(buf), TEXT("%s (0x%x)"), tmp, GetLastError());
+    }
+
+    if (tmp)
+    {
+        LocalFree(tmp);
+    }
+
+    return buf;
+}
+
+
+DWORD
+MsgToEventLog(DWORD flags, LPCTSTR format, ...)
+{
+    HANDLE hEventSource;
+    TCHAR msg[2][256];
+    DWORD error = 0;
+    LPCTSTR err_msg = TEXT("");
+    va_list arglist;
+
+    if (flags & MSG_FLAGS_SYS_CODE)
+    {
+        error = GetLastError();
+        err_msg = GetLastErrorText();
+    }
+
+    hEventSource = RegisterEventSource(NULL, APPNAME);
+    if (hEventSource != NULL)
+    {
+        openvpn_sntprintf(msg[0], _countof(msg[0]),
+                          TEXT("%s%s%s: %s"), APPNAME, service_instance,
+                          (flags & MSG_FLAGS_ERROR) ? TEXT(" error") : TEXT(""), err_msg);
+
+        va_start(arglist, format);
+        openvpn_vsntprintf(msg[1], _countof(msg[1]), format, arglist);
+        va_end(arglist);
+
+        const TCHAR *mesg[] = { msg[0], msg[1] };
+        ReportEvent(hEventSource, flags & MSG_FLAGS_ERROR ?
+                    EVENTLOG_ERROR_TYPE : EVENTLOG_INFORMATION_TYPE,
+                    0, 0, NULL, 2, 0, mesg, NULL);
+        DeregisterEventSource(hEventSource);
+    }
+
+    return error;
+}
+
+/* Convert a utf8 string to utf16. Caller should free the result */
+wchar_t *
+utf8to16(const char *utf8)
+{
+    int n = MultiByteToWideChar(CP_UTF8, 0, utf8, -1, NULL, 0);
+    wchar_t *utf16 = malloc(n * sizeof(wchar_t));
+    if (!utf16)
+    {
+        return NULL;
+    }
+    MultiByteToWideChar(CP_UTF8, 0, utf8, -1, utf16, n);
+    return utf16;
+}
+
+const wchar_t *
+get_win_sys_path(void)
+{
+    const wchar_t *default_sys_path = L"C:\\Windows\\system32";
+
+    if (!GetSystemDirectoryW(win_sys_path, _countof(win_sys_path)))
+    {
+        wcsncpy(win_sys_path, default_sys_path, _countof(win_sys_path));
+        win_sys_path[_countof(win_sys_path) - 1] = L'\0';
+    }
+
+    return win_sys_path;
+}
diff --git a/src/openvpnserv/interactive.c b/src/openvpnserv/interactive.c
new file mode 100644
index 0000000..aecbd84
--- /dev/null
+++ b/src/openvpnserv/interactive.c
@@ -0,0 +1,1981 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2012-2018 Heiko Hund <heiko.hund@sophos.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+
+#include "service.h"
+
+#include <winsock2.h>
+#include <ws2tcpip.h>
+#include <iphlpapi.h>
+#include <userenv.h>
+#include <accctrl.h>
+#include <aclapi.h>
+#include <stdio.h>
+#include <sddl.h>
+#include <shellapi.h>
+#include <mstcpip.h>
+
+#ifdef HAVE_VERSIONHELPERS_H
+#include <versionhelpers.h>
+#else
+#include "compat-versionhelpers.h"
+#endif
+
+#include "openvpn-msg.h"
+#include "validate.h"
+#include "block_dns.h"
+
+#define IO_TIMEOUT  2000 /*ms*/
+
+#define ERROR_OPENVPN_STARTUP  0x20000000
+#define ERROR_STARTUP_DATA     0x20000001
+#define ERROR_MESSAGE_DATA     0x20000002
+#define ERROR_MESSAGE_TYPE     0x20000003
+
+static SERVICE_STATUS_HANDLE service;
+static SERVICE_STATUS status = { .dwServiceType = SERVICE_WIN32_SHARE_PROCESS };
+static HANDLE exit_event = NULL;
+static settings_t settings;
+static HANDLE rdns_semaphore = NULL;
+#define RDNS_TIMEOUT 600  /* seconds to wait for the semaphore */
+
+
+openvpn_service_t interactive_service = {
+    interactive,
+    TEXT(PACKAGE_NAME "ServiceInteractive"),
+    TEXT(PACKAGE_NAME " Interactive Service"),
+    TEXT(SERVICE_DEPENDENCIES),
+    SERVICE_AUTO_START
+};
+
+
+typedef struct {
+    WCHAR *directory;
+    WCHAR *options;
+    WCHAR *std_input;
+} STARTUP_DATA;
+
+
+/* Datatype for linked lists */
+typedef struct _list_item {
+    struct _list_item *next;
+    LPVOID data;
+} list_item_t;
+
+
+/* Datatypes for undo information */
+typedef enum {
+    address,
+    route,
+    block_dns,
+    undo_dns4,
+    undo_dns6,
+    _undo_type_max
+} undo_type_t;
+typedef list_item_t *undo_lists_t[_undo_type_max];
+
+typedef struct {
+    HANDLE engine;
+    int index;
+    int metric_v4;
+    int metric_v6;
+} block_dns_data_t;
+
+
+static DWORD
+AddListItem(list_item_t **pfirst, LPVOID data)
+{
+    list_item_t *new_item = malloc(sizeof(list_item_t));
+    if (new_item == NULL)
+    {
+        return ERROR_OUTOFMEMORY;
+    }
+
+    new_item->next = *pfirst;
+    new_item->data = data;
+
+    *pfirst = new_item;
+    return NO_ERROR;
+}
+
+typedef BOOL (*match_fn_t) (LPVOID item, LPVOID ctx);
+
+static LPVOID
+RemoveListItem(list_item_t **pfirst, match_fn_t match, LPVOID ctx)
+{
+    LPVOID data = NULL;
+    list_item_t **pnext;
+
+    for (pnext = pfirst; *pnext; pnext = &(*pnext)->next)
+    {
+        list_item_t *item = *pnext;
+        if (!match(item->data, ctx))
+        {
+            continue;
+        }
+
+        /* Found item, remove from the list and free memory */
+        *pnext = item->next;
+        data = item->data;
+        free(item);
+        break;
+    }
+    return data;
+}
+
+
+static HANDLE
+CloseHandleEx(LPHANDLE handle)
+{
+    if (handle && *handle && *handle != INVALID_HANDLE_VALUE)
+    {
+        CloseHandle(*handle);
+        *handle = INVALID_HANDLE_VALUE;
+    }
+    return INVALID_HANDLE_VALUE;
+}
+
+
+static HANDLE
+InitOverlapped(LPOVERLAPPED overlapped)
+{
+    ZeroMemory(overlapped, sizeof(OVERLAPPED));
+    overlapped->hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+    return overlapped->hEvent;
+}
+
+
+static BOOL
+ResetOverlapped(LPOVERLAPPED overlapped)
+{
+    HANDLE io_event = overlapped->hEvent;
+    if (!ResetEvent(io_event))
+    {
+        return FALSE;
+    }
+    ZeroMemory(overlapped, sizeof(OVERLAPPED));
+    overlapped->hEvent = io_event;
+    return TRUE;
+}
+
+
+typedef enum {
+    peek,
+    read,
+    write
+} async_op_t;
+
+static DWORD
+AsyncPipeOp(async_op_t op, HANDLE pipe, LPVOID buffer, DWORD size, DWORD count, LPHANDLE events)
+{
+    int i;
+    BOOL success;
+    HANDLE io_event;
+    DWORD res, bytes = 0;
+    OVERLAPPED overlapped;
+    LPHANDLE handles = NULL;
+
+    io_event = InitOverlapped(&overlapped);
+    if (!io_event)
+    {
+        goto out;
+    }
+
+    handles = malloc((count + 1) * sizeof(HANDLE));
+    if (!handles)
+    {
+        goto out;
+    }
+
+    if (op == write)
+    {
+        success = WriteFile(pipe, buffer, size, NULL, &overlapped);
+    }
+    else
+    {
+        success = ReadFile(pipe, buffer, size, NULL, &overlapped);
+    }
+    if (!success && GetLastError() != ERROR_IO_PENDING && GetLastError() != ERROR_MORE_DATA)
+    {
+        goto out;
+    }
+
+    handles[0] = io_event;
+    for (i = 0; i < count; i++)
+    {
+        handles[i + 1] = events[i];
+    }
+
+    res = WaitForMultipleObjects(count + 1, handles, FALSE,
+                                 op == peek ? INFINITE : IO_TIMEOUT);
+    if (res != WAIT_OBJECT_0)
+    {
+        CancelIo(pipe);
+        goto out;
+    }
+
+    if (op == peek)
+    {
+        PeekNamedPipe(pipe, NULL, 0, NULL, &bytes, NULL);
+    }
+    else
+    {
+        GetOverlappedResult(pipe, &overlapped, &bytes, TRUE);
+    }
+
+out:
+    CloseHandleEx(&io_event);
+    free(handles);
+    return bytes;
+}
+
+static DWORD
+PeekNamedPipeAsync(HANDLE pipe, DWORD count, LPHANDLE events)
+{
+    return AsyncPipeOp(peek, pipe, NULL, 0, count, events);
+}
+
+static DWORD
+ReadPipeAsync(HANDLE pipe, LPVOID buffer, DWORD size, DWORD count, LPHANDLE events)
+{
+    return AsyncPipeOp(read, pipe, buffer, size, count, events);
+}
+
+static DWORD
+WritePipeAsync(HANDLE pipe, LPVOID data, DWORD size, DWORD count, LPHANDLE events)
+{
+    return AsyncPipeOp(write, pipe, data, size, count, events);
+}
+
+static VOID
+ReturnProcessId(HANDLE pipe, DWORD pid, DWORD count, LPHANDLE events)
+{
+    const WCHAR msg[] = L"Process ID";
+    WCHAR buf[22 + _countof(msg)]; /* 10 chars each for error and PID and 2 for line breaks */
+
+    /*
+     * Same format as error messages (3 line string) with error = 0 in
+     * 0x%08x format, PID on line 2 and a description "Process ID" on line 3
+     */
+    swprintf(buf, _countof(buf), L"0x%08x\n0x%08x\n%s", 0, pid, msg);
+    buf[_countof(buf) - 1] = '\0';
+
+    WritePipeAsync(pipe, buf, wcslen(buf) * 2, count, events);
+}
+
+static VOID
+ReturnError(HANDLE pipe, DWORD error, LPCWSTR func, DWORD count, LPHANDLE events)
+{
+    DWORD result_len;
+    LPWSTR result = L"0xffffffff\nFormatMessage failed\nCould not return result";
+    DWORD_PTR args[] = {
+        (DWORD_PTR) error,
+        (DWORD_PTR) func,
+        (DWORD_PTR) ""
+    };
+
+    if (error != ERROR_OPENVPN_STARTUP)
+    {
+        FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM
+                       |FORMAT_MESSAGE_ALLOCATE_BUFFER
+                       |FORMAT_MESSAGE_IGNORE_INSERTS,
+                       0, error, 0, (LPWSTR) &args[2], 0, NULL);
+    }
+
+    result_len = FormatMessageW(FORMAT_MESSAGE_FROM_STRING
+                                |FORMAT_MESSAGE_ALLOCATE_BUFFER
+                                |FORMAT_MESSAGE_ARGUMENT_ARRAY,
+                                L"0x%1!08x!\n%2!s!\n%3!s!", 0, 0,
+                                (LPWSTR) &result, 0, (va_list *) args);
+
+    WritePipeAsync(pipe, result, wcslen(result) * 2, count, events);
+#ifdef UNICODE
+    MsgToEventLog(MSG_FLAGS_ERROR, result);
+#else
+    MsgToEventLog(MSG_FLAGS_ERROR, "%S", result);
+#endif
+
+    if (error != ERROR_OPENVPN_STARTUP)
+    {
+        LocalFree((LPVOID) args[2]);
+    }
+    if (result_len)
+    {
+        LocalFree(result);
+    }
+}
+
+
+static VOID
+ReturnLastError(HANDLE pipe, LPCWSTR func)
+{
+    ReturnError(pipe, GetLastError(), func, 1, &exit_event);
+}
+
+
+static VOID
+ReturnOpenvpnOutput(HANDLE pipe, HANDLE ovpn_output, DWORD count, LPHANDLE events)
+{
+    WCHAR *wide_output = NULL;
+    CHAR output[512];
+    DWORD size;
+
+    ReadFile(ovpn_output, output, sizeof(output), &size, NULL);
+    if (size == 0)
+    {
+        return;
+    }
+
+    wide_output = malloc((size) * sizeof(WCHAR));
+    if (wide_output)
+    {
+        MultiByteToWideChar(CP_UTF8, 0, output, size, wide_output, size);
+        wide_output[size - 1] = 0;
+    }
+
+    ReturnError(pipe, ERROR_OPENVPN_STARTUP, wide_output, count, events);
+    free(wide_output);
+}
+
+/*
+ * Validate options against a white list. Also check the config_file is
+ * inside the config_dir. The white list is defined in validate.c
+ * Returns true on success, false on error with reason set in errmsg.
+ */
+static BOOL
+ValidateOptions(HANDLE pipe, const WCHAR *workdir, const WCHAR *options, WCHAR *errmsg, DWORD capacity)
+{
+    WCHAR **argv;
+    int argc;
+    BOOL ret = FALSE;
+    int i;
+    const WCHAR *msg1 = L"You have specified a config file location (%s relative to %s)"
+                        L" that requires admin approval. This error may be avoided"
+                        L" by adding your account to the \"%s\" group";
+
+    const WCHAR *msg2 = L"You have specified an option (%s) that may be used"
+                        L" only with admin approval. This error may be avoided"
+                        L" by adding your account to the \"%s\" group";
+
+    argv = CommandLineToArgvW(options, &argc);
+
+    if (!argv)
+    {
+        swprintf(errmsg, capacity,
+	         L"Cannot validate options: CommandLineToArgvW failed with error = 0x%08x",
+	         GetLastError());
+        errmsg[capacity-1] = L'\0';
+        goto out;
+    }
+
+    /* Note: argv[0] is the first option */
+    if (argc < 1)  /* no options */
+    {
+        ret = TRUE;
+        goto out;
+    }
+
+    /*
+     * If only one argument, it is the config file
+     */
+    if (argc == 1)
+    {
+        WCHAR *argv_tmp[2] = { L"--config", argv[0] };
+
+        if (!CheckOption(workdir, 2, argv_tmp, &settings))
+        {
+            swprintf(errmsg, capacity, msg1, argv[0], workdir,
+                     settings.ovpn_admin_group);
+            errmsg[capacity-1] = L'\0';
+        }
+        goto out;
+    }
+
+    for (i = 0; i < argc; ++i)
+    {
+        if (!IsOption(argv[i]))
+        {
+            continue;
+        }
+
+        if (!CheckOption(workdir, argc-i, &argv[i], &settings))
+        {
+            if (wcscmp(L"--config", argv[i]) == 0 && argc-i > 1)
+            {
+                swprintf(errmsg, capacity, msg1, argv[i+1], workdir,
+                         settings.ovpn_admin_group);
+            }
+            else
+            {
+                swprintf(errmsg, capacity, msg2, argv[i],
+                         settings.ovpn_admin_group);
+            }
+            errmsg[capacity-1] = L'\0';
+            goto out;
+        }
+    }
+
+    /* all options passed */
+    ret = TRUE;
+
+out:
+    if (argv)
+    {
+        LocalFree(argv);
+    }
+    return ret;
+}
+
+static BOOL
+GetStartupData(HANDLE pipe, STARTUP_DATA *sud)
+{
+    size_t len;
+    WCHAR *data = NULL;
+    DWORD size, bytes, read;
+
+    bytes = PeekNamedPipeAsync(pipe, 1, &exit_event);
+    if (bytes == 0)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("PeekNamedPipeAsync failed"));
+        ReturnLastError(pipe, L"PeekNamedPipeAsync");
+        goto err;
+    }
+
+    size = bytes / sizeof(*data);
+    if (size == 0)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("malformed startup data: 1 byte received"));
+        ReturnError(pipe, ERROR_STARTUP_DATA, L"GetStartupData", 1, &exit_event);
+        goto err;
+    }
+
+    data = malloc(bytes);
+    if (data == NULL)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("malloc failed"));
+        ReturnLastError(pipe, L"malloc");
+        goto err;
+    }
+
+    read = ReadPipeAsync(pipe, data, bytes, 1, &exit_event);
+    if (bytes != read)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("ReadPipeAsync failed"));
+        ReturnLastError(pipe, L"ReadPipeAsync");
+        goto err;
+    }
+
+    if (data[size - 1] != 0)
+    {
+        MsgToEventLog(M_ERR, TEXT("Startup data is not NULL terminated"));
+        ReturnError(pipe, ERROR_STARTUP_DATA, L"GetStartupData", 1, &exit_event);
+        goto err;
+    }
+
+    sud->directory = data;
+    len = wcslen(sud->directory) + 1;
+    size -= len;
+    if (size <= 0)
+    {
+        MsgToEventLog(M_ERR, TEXT("Startup data ends at working directory"));
+        ReturnError(pipe, ERROR_STARTUP_DATA, L"GetStartupData", 1, &exit_event);
+        goto err;
+    }
+
+    sud->options = sud->directory + len;
+    len = wcslen(sud->options) + 1;
+    size -= len;
+    if (size <= 0)
+    {
+        MsgToEventLog(M_ERR, TEXT("Startup data ends at command line options"));
+        ReturnError(pipe, ERROR_STARTUP_DATA, L"GetStartupData", 1, &exit_event);
+        goto err;
+    }
+
+    sud->std_input = sud->options + len;
+    return TRUE;
+
+err:
+    sud->directory = NULL;		/* caller must not free() */
+    free(data);
+    return FALSE;
+}
+
+
+static VOID
+FreeStartupData(STARTUP_DATA *sud)
+{
+    free(sud->directory);
+}
+
+
+static SOCKADDR_INET
+sockaddr_inet(short family, inet_address_t *addr)
+{
+    SOCKADDR_INET sa_inet;
+    ZeroMemory(&sa_inet, sizeof(sa_inet));
+    sa_inet.si_family = family;
+    if (family == AF_INET)
+    {
+        sa_inet.Ipv4.sin_addr = addr->ipv4;
+    }
+    else if (family == AF_INET6)
+    {
+        sa_inet.Ipv6.sin6_addr = addr->ipv6;
+    }
+    return sa_inet;
+}
+
+static DWORD
+InterfaceLuid(const char *iface_name, PNET_LUID luid)
+{
+    NETIO_STATUS status;
+    LPWSTR wide_name = utf8to16(iface_name);
+
+    if (wide_name)
+    {
+        status = ConvertInterfaceAliasToLuid(wide_name, luid);
+        free(wide_name);
+    }
+    else
+    {
+        status = ERROR_OUTOFMEMORY;
+    }
+    return status;
+}
+
+static BOOL
+CmpAddress(LPVOID item, LPVOID address)
+{
+    return memcmp(item, address, sizeof(MIB_UNICASTIPADDRESS_ROW)) == 0 ? TRUE : FALSE;
+}
+
+static DWORD
+DeleteAddress(PMIB_UNICASTIPADDRESS_ROW addr_row)
+{
+    return DeleteUnicastIpAddressEntry(addr_row);
+}
+
+static DWORD
+HandleAddressMessage(address_message_t *msg, undo_lists_t *lists)
+{
+    DWORD err;
+    PMIB_UNICASTIPADDRESS_ROW addr_row;
+    BOOL add = msg->header.type == msg_add_address;
+
+    addr_row = malloc(sizeof(*addr_row));
+    if (addr_row == NULL)
+    {
+        return ERROR_OUTOFMEMORY;
+    }
+
+    InitializeUnicastIpAddressEntry(addr_row);
+    addr_row->Address = sockaddr_inet(msg->family, &msg->address);
+    addr_row->OnLinkPrefixLength = (UINT8) msg->prefix_len;
+
+    if (msg->iface.index != -1)
+    {
+        addr_row->InterfaceIndex = msg->iface.index;
+    }
+    else
+    {
+        NET_LUID luid;
+        err = InterfaceLuid(msg->iface.name, &luid);
+        if (err)
+        {
+            goto out;
+        }
+        addr_row->InterfaceLuid = luid;
+    }
+
+    if (add)
+    {
+        err = CreateUnicastIpAddressEntry(addr_row);
+        if (err)
+        {
+            goto out;
+        }
+
+        err = AddListItem(&(*lists)[address], addr_row);
+        if (err)
+        {
+            DeleteAddress(addr_row);
+        }
+    }
+    else
+    {
+        err = DeleteAddress(addr_row);
+        if (err)
+        {
+            goto out;
+        }
+
+        free(RemoveListItem(&(*lists)[address], CmpAddress, addr_row));
+    }
+
+out:
+    if (!add || err)
+    {
+        free(addr_row);
+    }
+
+    return err;
+}
+
+static BOOL
+CmpRoute(LPVOID item, LPVOID route)
+{
+    return memcmp(item, route, sizeof(MIB_IPFORWARD_ROW2)) == 0 ? TRUE : FALSE;
+}
+
+static DWORD
+DeleteRoute(PMIB_IPFORWARD_ROW2 fwd_row)
+{
+    return DeleteIpForwardEntry2(fwd_row);
+}
+
+static DWORD
+HandleRouteMessage(route_message_t *msg, undo_lists_t *lists)
+{
+    DWORD err;
+    PMIB_IPFORWARD_ROW2 fwd_row;
+    BOOL add = msg->header.type == msg_add_route;
+
+    fwd_row = malloc(sizeof(*fwd_row));
+    if (fwd_row == NULL)
+    {
+        return ERROR_OUTOFMEMORY;
+    }
+
+    ZeroMemory(fwd_row, sizeof(*fwd_row));
+    fwd_row->ValidLifetime = 0xffffffff;
+    fwd_row->PreferredLifetime = 0xffffffff;
+    fwd_row->Protocol = MIB_IPPROTO_NETMGMT;
+    fwd_row->Metric = msg->metric;
+    fwd_row->DestinationPrefix.Prefix = sockaddr_inet(msg->family, &msg->prefix);
+    fwd_row->DestinationPrefix.PrefixLength = (UINT8) msg->prefix_len;
+    fwd_row->NextHop = sockaddr_inet(msg->family, &msg->gateway);
+
+    if (msg->iface.index != -1)
+    {
+        fwd_row->InterfaceIndex = msg->iface.index;
+    }
+    else if (strlen(msg->iface.name))
+    {
+        NET_LUID luid;
+        err = InterfaceLuid(msg->iface.name, &luid);
+        if (err)
+        {
+            goto out;
+        }
+        fwd_row->InterfaceLuid = luid;
+    }
+
+    if (add)
+    {
+        err = CreateIpForwardEntry2(fwd_row);
+        if (err)
+        {
+            goto out;
+        }
+
+        err = AddListItem(&(*lists)[route], fwd_row);
+        if (err)
+        {
+            DeleteRoute(fwd_row);
+        }
+    }
+    else
+    {
+        err = DeleteRoute(fwd_row);
+        if (err)
+        {
+            goto out;
+        }
+
+        free(RemoveListItem(&(*lists)[route], CmpRoute, fwd_row));
+    }
+
+out:
+    if (!add || err)
+    {
+        free(fwd_row);
+    }
+
+    return err;
+}
+
+
+static DWORD
+HandleFlushNeighborsMessage(flush_neighbors_message_t *msg)
+{
+    if (msg->family == AF_INET)
+    {
+        return FlushIpNetTable(msg->iface.index);
+    }
+
+    return FlushIpNetTable2(msg->family, msg->iface.index);
+}
+
+static void
+BlockDNSErrHandler(DWORD err, const char *msg)
+{
+    TCHAR buf[256];
+    LPCTSTR err_str;
+
+    if (!err)
+    {
+        return;
+    }
+
+    err_str = TEXT("Unknown Win32 Error");
+
+    if (FormatMessage(FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_FROM_SYSTEM
+                      | FORMAT_MESSAGE_ARGUMENT_ARRAY,
+                      NULL, err, 0, buf, sizeof(buf), NULL))
+    {
+        err_str = buf;
+    }
+
+#ifdef UNICODE
+    MsgToEventLog(M_ERR, L"%S (status = %lu): %s", msg, err, err_str);
+#else
+    MsgToEventLog(M_ERR, "%s (status = %lu): %s", msg, err, err_str);
+#endif
+
+}
+
+/* Use an always-true match_fn to get the head of the list */
+static BOOL
+CmpEngine(LPVOID item, LPVOID any)
+{
+    return TRUE;
+}
+
+static DWORD
+HandleBlockDNSMessage(const block_dns_message_t *msg, undo_lists_t *lists)
+{
+    DWORD err = 0;
+    block_dns_data_t *interface_data;
+    HANDLE engine = NULL;
+    LPCWSTR exe_path;
+
+#ifdef UNICODE
+    exe_path = settings.exe_path;
+#else
+    WCHAR wide_path[MAX_PATH];
+    MultiByteToWideChar(CP_UTF8, 0, settings.exe_path, MAX_PATH, wide_path, MAX_PATH);
+    exe_path = wide_path;
+#endif
+
+    if (msg->header.type == msg_add_block_dns)
+    {
+        err = add_block_dns_filters(&engine, msg->iface.index, exe_path, BlockDNSErrHandler);
+        if (!err)
+        {
+            interface_data = malloc(sizeof(block_dns_data_t));
+            if (!interface_data)
+            {
+                return ERROR_OUTOFMEMORY;
+            }
+            interface_data->engine = engine;
+            interface_data->index = msg->iface.index;
+            int is_auto = 0;
+            interface_data->metric_v4 = get_interface_metric(msg->iface.index,
+                                                             AF_INET, &is_auto);
+            if (is_auto)
+            {
+                interface_data->metric_v4 = 0;
+            }
+            interface_data->metric_v6 = get_interface_metric(msg->iface.index,
+                                                             AF_INET6, &is_auto);
+            if (is_auto)
+            {
+                interface_data->metric_v6 = 0;
+            }
+            err = AddListItem(&(*lists)[block_dns], interface_data);
+            if (!err)
+            {
+                err = set_interface_metric(msg->iface.index, AF_INET,
+                                           BLOCK_DNS_IFACE_METRIC);
+                if (!err)
+                {
+                    set_interface_metric(msg->iface.index, AF_INET6,
+                                         BLOCK_DNS_IFACE_METRIC);
+                }
+            }
+        }
+    }
+    else
+    {
+        interface_data = RemoveListItem(&(*lists)[block_dns], CmpEngine, NULL);
+        if (interface_data)
+        {
+            engine = interface_data->engine;
+            err = delete_block_dns_filters(engine);
+            engine = NULL;
+            if (interface_data->metric_v4 >= 0)
+            {
+                set_interface_metric(msg->iface.index, AF_INET,
+                                     interface_data->metric_v4);
+            }
+            if (interface_data->metric_v6 >= 0)
+            {
+                set_interface_metric(msg->iface.index, AF_INET6,
+                                     interface_data->metric_v6);
+            }
+            free(interface_data);
+        }
+        else
+        {
+            MsgToEventLog(M_ERR, TEXT("No previous block DNS filters to delete"));
+        }
+    }
+
+    if (err && engine)
+    {
+        delete_block_dns_filters(engine);
+    }
+
+    return err;
+}
+
+/*
+ * Execute a command and return its exit code. If timeout > 0, terminate
+ * the process if still running after timeout milliseconds. In that case
+ * the return value is the windows error code WAIT_TIMEOUT = 0x102
+ */
+static DWORD
+ExecCommand(const WCHAR *argv0, const WCHAR *cmdline, DWORD timeout)
+{
+    DWORD exit_code;
+    STARTUPINFOW si;
+    PROCESS_INFORMATION pi;
+    DWORD proc_flags = CREATE_NO_WINDOW|CREATE_UNICODE_ENVIRONMENT;
+    WCHAR *cmdline_dup = NULL;
+
+    ZeroMemory(&si, sizeof(si));
+    ZeroMemory(&pi, sizeof(pi));
+
+    si.cb = sizeof(si);
+
+    /* CreateProcess needs a modifiable cmdline: make a copy */
+    cmdline_dup = wcsdup(cmdline);
+    if (cmdline_dup && CreateProcessW(argv0, cmdline_dup, NULL, NULL, FALSE,
+                                      proc_flags, NULL, NULL, &si, &pi) )
+    {
+        WaitForSingleObject(pi.hProcess, timeout ? timeout : INFINITE);
+        if (!GetExitCodeProcess(pi.hProcess, &exit_code))
+        {
+            MsgToEventLog(M_SYSERR, TEXT("ExecCommand: Error getting exit_code:"));
+            exit_code = GetLastError();
+        }
+        else if (exit_code == STILL_ACTIVE)
+        {
+            exit_code = WAIT_TIMEOUT; /* Windows error code 0x102 */
+
+            /* kill without impunity */
+            TerminateProcess(pi.hProcess, exit_code);
+            MsgToEventLog(M_ERR, TEXT("ExecCommand: \"%s %s\" killed after timeout"),
+                          argv0, cmdline);
+        }
+        else if (exit_code)
+        {
+            MsgToEventLog(M_ERR, TEXT("ExecCommand: \"%s %s\" exited with status = %lu"),
+                          argv0, cmdline, exit_code);
+        }
+        else
+        {
+            MsgToEventLog(M_INFO, TEXT("ExecCommand: \"%s %s\" completed"), argv0, cmdline);
+        }
+
+        CloseHandle(pi.hProcess);
+        CloseHandle(pi.hThread);
+    }
+    else
+    {
+        exit_code = GetLastError();
+        MsgToEventLog(M_SYSERR, TEXT("ExecCommand: could not run \"%s %s\" :"),
+                      argv0, cmdline);
+    }
+
+    free(cmdline_dup);
+    return exit_code;
+}
+
+/*
+ * Entry point for register-dns thread.
+ */
+static DWORD WINAPI
+RegisterDNS(LPVOID unused)
+{
+    DWORD err;
+    DWORD i;
+    DWORD timeout = RDNS_TIMEOUT * 1000; /* in milliseconds */
+
+    /* path of ipconfig command */
+    WCHAR ipcfg[MAX_PATH];
+
+    struct
+    {
+        WCHAR *argv0;
+        WCHAR *cmdline;
+        DWORD timeout;
+    } cmds [] = {
+        { ipcfg, L"ipconfig /flushdns",    timeout },
+        { ipcfg, L"ipconfig /registerdns", timeout },
+    };
+    int ncmds = sizeof(cmds) / sizeof(cmds[0]);
+
+    HANDLE wait_handles[2] = {rdns_semaphore, exit_event};
+
+    swprintf(ipcfg, _countof(ipcfg), L"%s\\%s", get_win_sys_path(), L"ipconfig.exe");
+    ipcfg[_countof(ipcfg) - 1] = L'\0';
+
+    if (WaitForMultipleObjects(2, wait_handles, FALSE, timeout) == WAIT_OBJECT_0)
+    {
+        /* Semaphore locked */
+        for (i = 0; i < ncmds; ++i)
+        {
+            ExecCommand(cmds[i].argv0, cmds[i].cmdline, cmds[i].timeout);
+        }
+        err = 0;
+        if (!ReleaseSemaphore(rdns_semaphore, 1, NULL) )
+        {
+            err = MsgToEventLog(M_SYSERR, TEXT("RegisterDNS: Failed to release regsiter-dns semaphore:"));
+        }
+    }
+    else
+    {
+        MsgToEventLog(M_ERR, TEXT("RegisterDNS: Failed to lock register-dns semaphore"));
+        err = ERROR_SEM_TIMEOUT; /* Windows error code 0x79 */
+    }
+    return err;
+}
+
+static DWORD
+HandleRegisterDNSMessage(void)
+{
+    DWORD err;
+    HANDLE thread = NULL;
+
+    /* Delegate this job to a sub-thread */
+    thread = CreateThread(NULL, 0, RegisterDNS, NULL, 0, NULL);
+
+    /*
+     * We don't add these thread handles to the undo list -- the thread and
+     * processes it spawns are all supposed to terminate or timeout by themselves.
+     */
+    if (thread)
+    {
+        err = 0;
+        CloseHandle(thread);
+    }
+    else
+    {
+        err = GetLastError();
+    }
+
+    return err;
+}
+
+/**
+ * Run the command: netsh interface $proto $action dns $if_name $addr [validate=no]
+ * @param  action      "delete" or "add"
+ * @param  proto       "ipv6" or "ip"
+ * @param  if_name     "name_of_interface"
+ * @param  addr         IPv4 (for proto = ip) or IPv6 address as a string
+ *
+ * If addr is null and action = "delete" all addresses are deleted.
+ */
+static DWORD
+netsh_dns_cmd(const wchar_t *action, const wchar_t *proto, const wchar_t *if_name, const wchar_t *addr)
+{
+    DWORD err = 0;
+    int timeout = 30000; /* in msec */
+    wchar_t argv0[MAX_PATH];
+    wchar_t *cmdline = NULL;
+
+    if (!addr)
+    {
+        if (wcscmp(action, L"delete") == 0)
+        {
+            addr = L"all";
+        }
+        else /* nothing to do -- return success*/
+        {
+            goto out;
+        }
+    }
+
+    /* Path of netsh */
+    swprintf(argv0, _countof(argv0), L"%s\\%s", get_win_sys_path(), L"netsh.exe");
+    argv0[_countof(argv0) - 1] = L'\0';
+
+    /* cmd template:
+     * netsh interface $proto $action dns $if_name $addr [validate=no]
+     */
+    const wchar_t *fmt = L"netsh interface %s %s dns \"%s\" %s";
+
+    /* max cmdline length in wchars -- include room for worst case and some */
+    int ncmdline = wcslen(fmt) + wcslen(if_name) + wcslen(addr) + 32 + 1;
+    cmdline = malloc(ncmdline*sizeof(wchar_t));
+    if (!cmdline)
+    {
+        err = ERROR_OUTOFMEMORY;
+        goto out;
+    }
+
+    openvpn_sntprintf(cmdline, ncmdline, fmt, proto, action, if_name, addr);
+
+    if (IsWindows7OrGreater())
+    {
+        wcsncat(cmdline, L" validate=no", ncmdline - wcslen(cmdline) - 1);
+    }
+    err = ExecCommand(argv0, cmdline, timeout);
+
+out:
+    free(cmdline);
+    return err;
+}
+
+/* Delete all IPv4 or IPv6 dns servers for an interface */
+static DWORD
+DeleteDNS(short family, wchar_t *if_name)
+{
+    wchar_t *proto = (family == AF_INET6) ? L"ipv6" : L"ip";
+    return netsh_dns_cmd(L"delete", proto, if_name, NULL);
+}
+
+/* Add an IPv4 or IPv6 dns server to an interface */
+static DWORD
+AddDNS(short family, wchar_t *if_name, wchar_t *addr)
+{
+    wchar_t *proto = (family == AF_INET6) ? L"ipv6" : L"ip";
+    return netsh_dns_cmd(L"add", proto, if_name, addr);
+}
+
+static BOOL
+CmpWString(LPVOID item, LPVOID str)
+{
+    return (wcscmp(item, str) == 0) ? TRUE : FALSE;
+}
+
+static DWORD
+HandleDNSConfigMessage(const dns_cfg_message_t *msg, undo_lists_t *lists)
+{
+    DWORD err = 0;
+    wchar_t addr[46]; /* large enough to hold string representation of an ipv4 / ipv6 address */
+    undo_type_t undo_type = (msg->family == AF_INET6) ? undo_dns4 : undo_dns6;
+    int addr_len = msg->addr_len;
+
+    /* sanity check */
+    if (addr_len > _countof(msg->addr))
+    {
+        addr_len = _countof(msg->addr);
+    }
+
+    if (!msg->iface.name[0]) /* interface name is required */
+    {
+        return ERROR_MESSAGE_DATA;
+    }
+
+    wchar_t *wide_name = utf8to16(msg->iface.name); /* utf8 to wide-char */
+    if (!wide_name)
+    {
+        return ERROR_OUTOFMEMORY;
+    }
+
+    /* We delete all current addresses before adding any
+     * OR if the message type is del_dns_cfg
+     */
+    if (addr_len > 0 || msg->header.type == msg_del_dns_cfg)
+    {
+        err = DeleteDNS(msg->family, wide_name);
+        if (err)
+        {
+            goto out;
+        }
+        free(RemoveListItem(&(*lists)[undo_type], CmpWString, wide_name));
+    }
+
+    if (msg->header.type == msg_del_dns_cfg) /* job done */
+    {
+        goto out;
+    }
+
+    for (int i = 0; i < addr_len; ++i)
+    {
+        if (msg->family == AF_INET6)
+        {
+            RtlIpv6AddressToStringW(&msg->addr[i].ipv6, addr);
+        }
+        else
+        {
+            RtlIpv4AddressToStringW(&msg->addr[i].ipv4, addr);
+        }
+        err = AddDNS(msg->family, wide_name, addr);
+        if (i == 0 && err)
+        {
+            goto out;
+        }
+        /* We do not check for duplicate addresses, so any error in adding
+         * additional addresses is ignored.
+         */
+    }
+
+    if (msg->addr_len > 0)
+    {
+        wchar_t *tmp_name = wcsdup(wide_name);
+        if (!tmp_name || AddListItem(&(*lists)[undo_type], tmp_name))
+        {
+            free(tmp_name);
+            DeleteDNS(msg->family, wide_name);
+            err = ERROR_OUTOFMEMORY;
+            goto out;
+        }
+    }
+
+    err = 0;
+
+out:
+    free(wide_name);
+    return err;
+}
+
+static DWORD
+HandleEnableDHCPMessage(const enable_dhcp_message_t *dhcp)
+{
+    DWORD err = 0;
+    DWORD timeout = 5000; /* in milli seconds */
+    wchar_t argv0[MAX_PATH];
+
+    /* Path of netsh */
+    swprintf(argv0, _countof(argv0), L"%s\\%s", get_win_sys_path(), L"netsh.exe");
+    argv0[_countof(argv0) - 1] = L'\0';
+
+    /* cmd template:
+     * netsh interface ipv4 set address name=$if_index source=dhcp
+     */
+    const wchar_t *fmt = L"netsh interface ipv4 set address name=\"%d\" source=dhcp";
+
+    /* max cmdline length in wchars -- include room for if index:
+     * 10 chars for 32 bit int in decimal and +1 for NUL
+     */
+    size_t ncmdline = wcslen(fmt) + 10 + 1;
+    wchar_t *cmdline = malloc(ncmdline*sizeof(wchar_t));
+    if (!cmdline)
+    {
+        err = ERROR_OUTOFMEMORY;
+        return err;
+    }
+
+    openvpn_sntprintf(cmdline, ncmdline, fmt, dhcp->iface.index);
+
+    err = ExecCommand(argv0, cmdline, timeout);
+
+    /* Note: This could fail if dhcp is already enabled, so the caller
+     * may not want to treat errors as FATAL.
+     */
+
+    free(cmdline);
+    return err;
+}
+
+static VOID
+HandleMessage(HANDLE pipe, DWORD bytes, DWORD count, LPHANDLE events, undo_lists_t *lists)
+{
+    DWORD read;
+    union {
+        message_header_t header;
+        address_message_t address;
+        route_message_t route;
+        flush_neighbors_message_t flush_neighbors;
+        block_dns_message_t block_dns;
+        dns_cfg_message_t dns;
+        enable_dhcp_message_t dhcp;
+    } msg;
+    ack_message_t ack = {
+        .header = {
+            .type = msg_acknowledgement,
+            .size = sizeof(ack),
+            .message_id = -1
+        },
+        .error_number = ERROR_MESSAGE_DATA
+    };
+
+    read = ReadPipeAsync(pipe, &msg, bytes, count, events);
+    if (read != bytes || read < sizeof(msg.header) || read != msg.header.size)
+    {
+        goto out;
+    }
+
+    ack.header.message_id = msg.header.message_id;
+
+    switch (msg.header.type)
+    {
+        case msg_add_address:
+        case msg_del_address:
+            if (msg.header.size == sizeof(msg.address))
+            {
+                ack.error_number = HandleAddressMessage(&msg.address, lists);
+            }
+            break;
+
+        case msg_add_route:
+        case msg_del_route:
+            if (msg.header.size == sizeof(msg.route))
+            {
+                ack.error_number = HandleRouteMessage(&msg.route, lists);
+            }
+            break;
+
+        case msg_flush_neighbors:
+            if (msg.header.size == sizeof(msg.flush_neighbors))
+            {
+                ack.error_number = HandleFlushNeighborsMessage(&msg.flush_neighbors);
+            }
+            break;
+
+        case msg_add_block_dns:
+        case msg_del_block_dns:
+            if (msg.header.size == sizeof(msg.block_dns))
+            {
+                ack.error_number = HandleBlockDNSMessage(&msg.block_dns, lists);
+            }
+            break;
+
+        case msg_register_dns:
+            ack.error_number = HandleRegisterDNSMessage();
+            break;
+
+        case msg_add_dns_cfg:
+        case msg_del_dns_cfg:
+            ack.error_number = HandleDNSConfigMessage(&msg.dns, lists);
+            break;
+
+        case msg_enable_dhcp:
+            if (msg.header.size == sizeof(msg.dhcp))
+            {
+                ack.error_number = HandleEnableDHCPMessage(&msg.dhcp);
+            }
+            break;
+
+        default:
+            ack.error_number = ERROR_MESSAGE_TYPE;
+            MsgToEventLog(MSG_FLAGS_ERROR, TEXT("Unknown message type %d"), msg.header.type);
+            break;
+    }
+
+out:
+    WritePipeAsync(pipe, &ack, sizeof(ack), count, events);
+}
+
+
+static VOID
+Undo(undo_lists_t *lists)
+{
+    undo_type_t type;
+    block_dns_data_t *interface_data;
+    for (type = 0; type < _undo_type_max; type++)
+    {
+        list_item_t **pnext = &(*lists)[type];
+        while (*pnext)
+        {
+            list_item_t *item = *pnext;
+            switch (type)
+            {
+                case address:
+                    DeleteAddress(item->data);
+                    break;
+
+                case route:
+                    DeleteRoute(item->data);
+                    break;
+
+                case undo_dns4:
+                    DeleteDNS(AF_INET, item->data);
+                    break;
+
+                case undo_dns6:
+                    DeleteDNS(AF_INET6, item->data);
+                    break;
+
+                case block_dns:
+                    interface_data = (block_dns_data_t*)(item->data);
+                    delete_block_dns_filters(interface_data->engine);
+                    if (interface_data->metric_v4 >= 0)
+                    {
+                        set_interface_metric(interface_data->index, AF_INET,
+                                             interface_data->metric_v4);
+                    }
+                    if (interface_data->metric_v6 >= 0)
+                    {
+                        set_interface_metric(interface_data->index, AF_INET6,
+                                             interface_data->metric_v6);
+                    }
+                    break;
+            }
+
+            /* Remove from the list and free memory */
+            *pnext = item->next;
+            free(item->data);
+            free(item);
+        }
+    }
+}
+
+static DWORD WINAPI
+RunOpenvpn(LPVOID p)
+{
+    HANDLE pipe = p;
+    HANDLE ovpn_pipe = NULL, svc_pipe = NULL;
+    PTOKEN_USER svc_user = NULL, ovpn_user = NULL;
+    HANDLE svc_token = NULL, imp_token = NULL, pri_token = NULL;
+    HANDLE stdin_read = NULL, stdin_write = NULL;
+    HANDLE stdout_write = NULL;
+    DWORD pipe_mode, len, exit_code = 0;
+    STARTUP_DATA sud = { 0, 0, 0 };
+    STARTUPINFOW startup_info;
+    PROCESS_INFORMATION proc_info;
+    LPVOID user_env = NULL;
+    TCHAR ovpn_pipe_name[256]; /* The entire pipe name string can be up to 256 characters long according to MSDN. */
+    LPCWSTR exe_path;
+    WCHAR *cmdline = NULL;
+    size_t cmdline_size;
+    undo_lists_t undo_lists;
+    WCHAR errmsg[512] = L"";
+
+    SECURITY_ATTRIBUTES inheritable = {
+        .nLength = sizeof(inheritable),
+        .lpSecurityDescriptor = NULL,
+        .bInheritHandle = TRUE
+    };
+
+    PACL ovpn_dacl;
+    EXPLICIT_ACCESS ea[2];
+    SECURITY_DESCRIPTOR ovpn_sd;
+    SECURITY_ATTRIBUTES ovpn_sa = {
+        .nLength = sizeof(ovpn_sa),
+        .lpSecurityDescriptor = &ovpn_sd,
+        .bInheritHandle = FALSE
+    };
+
+    ZeroMemory(&ea, sizeof(ea));
+    ZeroMemory(&startup_info, sizeof(startup_info));
+    ZeroMemory(&undo_lists, sizeof(undo_lists));
+    ZeroMemory(&proc_info, sizeof(proc_info));
+
+    if (!GetStartupData(pipe, &sud))
+    {
+        goto out;
+    }
+
+    if (!InitializeSecurityDescriptor(&ovpn_sd, SECURITY_DESCRIPTOR_REVISION))
+    {
+        ReturnLastError(pipe, L"InitializeSecurityDescriptor");
+        goto out;
+    }
+
+    /* Get SID of user the service is running under */
+    if (!OpenProcessToken(GetCurrentProcess(), TOKEN_QUERY, &svc_token))
+    {
+        ReturnLastError(pipe, L"OpenProcessToken");
+        goto out;
+    }
+    len = 0;
+    while (!GetTokenInformation(svc_token, TokenUser, svc_user, len, &len))
+    {
+        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+        {
+            ReturnLastError(pipe, L"GetTokenInformation (service token)");
+            goto out;
+        }
+        free(svc_user);
+        svc_user = malloc(len);
+        if (svc_user == NULL)
+        {
+            ReturnLastError(pipe, L"malloc (service token user)");
+            goto out;
+        }
+    }
+    if (!IsValidSid(svc_user->User.Sid))
+    {
+        ReturnLastError(pipe, L"IsValidSid (service token user)");
+        goto out;
+    }
+
+    if (!ImpersonateNamedPipeClient(pipe))
+    {
+        ReturnLastError(pipe, L"ImpersonateNamedPipeClient");
+        goto out;
+    }
+    if (!OpenThreadToken(GetCurrentThread(), TOKEN_ALL_ACCESS, FALSE, &imp_token))
+    {
+        ReturnLastError(pipe, L"OpenThreadToken");
+        goto out;
+    }
+    len = 0;
+    while (!GetTokenInformation(imp_token, TokenUser, ovpn_user, len, &len))
+    {
+        if (GetLastError() != ERROR_INSUFFICIENT_BUFFER)
+        {
+            ReturnLastError(pipe, L"GetTokenInformation (impersonation token)");
+            goto out;
+        }
+        free(ovpn_user);
+        ovpn_user = malloc(len);
+        if (ovpn_user == NULL)
+        {
+            ReturnLastError(pipe, L"malloc (impersonation token user)");
+            goto out;
+        }
+    }
+    if (!IsValidSid(ovpn_user->User.Sid))
+    {
+        ReturnLastError(pipe, L"IsValidSid (impersonation token user)");
+        goto out;
+    }
+
+    /*
+     * Only authorized users are allowed to use any command line options or
+     * have the config file in locations other than the global config directory.
+     *
+     * Check options are white-listed and config is in the global directory
+     * OR user is authorized to run any config.
+     */
+    if (!ValidateOptions(pipe, sud.directory, sud.options, errmsg, _countof(errmsg))
+        && !IsAuthorizedUser(ovpn_user->User.Sid, imp_token, settings.ovpn_admin_group))
+    {
+        ReturnError(pipe, ERROR_STARTUP_DATA, errmsg, 1, &exit_event);
+        goto out;
+    }
+
+    /* OpenVPN process DACL entry for access by service and user */
+    ea[0].grfAccessPermissions = SPECIFIC_RIGHTS_ALL | STANDARD_RIGHTS_ALL;
+    ea[0].grfAccessMode = SET_ACCESS;
+    ea[0].grfInheritance = NO_INHERITANCE;
+    ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+    ea[0].Trustee.TrusteeType = TRUSTEE_IS_UNKNOWN;
+    ea[0].Trustee.ptstrName = (LPTSTR) svc_user->User.Sid;
+    ea[1].grfAccessPermissions = READ_CONTROL | SYNCHRONIZE | PROCESS_VM_READ
+                                 |SYNCHRONIZE | PROCESS_TERMINATE | PROCESS_QUERY_INFORMATION;
+    ea[1].grfAccessMode = SET_ACCESS;
+    ea[1].grfInheritance = NO_INHERITANCE;
+    ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+    ea[1].Trustee.TrusteeType = TRUSTEE_IS_UNKNOWN;
+    ea[1].Trustee.ptstrName = (LPTSTR) ovpn_user->User.Sid;
+
+    /* Set owner and DACL of OpenVPN security descriptor */
+    if (!SetSecurityDescriptorOwner(&ovpn_sd, svc_user->User.Sid, FALSE))
+    {
+        ReturnLastError(pipe, L"SetSecurityDescriptorOwner");
+        goto out;
+    }
+    if (SetEntriesInAcl(2, ea, NULL, &ovpn_dacl) != ERROR_SUCCESS)
+    {
+        ReturnLastError(pipe, L"SetEntriesInAcl");
+        goto out;
+    }
+    if (!SetSecurityDescriptorDacl(&ovpn_sd, TRUE, ovpn_dacl, FALSE))
+    {
+        ReturnLastError(pipe, L"SetSecurityDescriptorDacl");
+        goto out;
+    }
+
+    /* Create primary token from impersonation token */
+    if (!DuplicateTokenEx(imp_token, TOKEN_ALL_ACCESS, NULL, 0, TokenPrimary, &pri_token))
+    {
+        ReturnLastError(pipe, L"DuplicateTokenEx");
+        goto out;
+    }
+
+    /* use /dev/null for stdout of openvpn (client should use --log for output) */
+    stdout_write = CreateFile(_T("NUL"), GENERIC_WRITE, FILE_SHARE_WRITE,
+                              &inheritable, OPEN_EXISTING, 0, NULL);
+    if (stdout_write == INVALID_HANDLE_VALUE)
+    {
+        ReturnLastError(pipe, L"CreateFile for stdout");
+        goto out;
+    }
+
+    if (!CreatePipe(&stdin_read, &stdin_write, &inheritable, 0)
+        || !SetHandleInformation(stdin_write, HANDLE_FLAG_INHERIT, 0))
+    {
+        ReturnLastError(pipe, L"CreatePipe");
+        goto out;
+    }
+
+    openvpn_sntprintf(ovpn_pipe_name, _countof(ovpn_pipe_name),
+                      TEXT("\\\\.\\pipe\\" PACKAGE "%s\\service_%lu"), service_instance, GetCurrentThreadId());
+    ovpn_pipe = CreateNamedPipe(ovpn_pipe_name,
+                                PIPE_ACCESS_DUPLEX | FILE_FLAG_FIRST_PIPE_INSTANCE | FILE_FLAG_OVERLAPPED,
+                                PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE | PIPE_WAIT, 1, 128, 128, 0, NULL);
+    if (ovpn_pipe == INVALID_HANDLE_VALUE)
+    {
+        ReturnLastError(pipe, L"CreateNamedPipe");
+        goto out;
+    }
+
+    svc_pipe = CreateFile(ovpn_pipe_name, GENERIC_READ | GENERIC_WRITE, 0,
+                          &inheritable, OPEN_EXISTING, 0, NULL);
+    if (svc_pipe == INVALID_HANDLE_VALUE)
+    {
+        ReturnLastError(pipe, L"CreateFile");
+        goto out;
+    }
+
+    pipe_mode = PIPE_READMODE_MESSAGE;
+    if (!SetNamedPipeHandleState(svc_pipe, &pipe_mode, NULL, NULL))
+    {
+        ReturnLastError(pipe, L"SetNamedPipeHandleState");
+        goto out;
+    }
+
+    cmdline_size = wcslen(sud.options) + 128;
+    cmdline = malloc(cmdline_size * sizeof(*cmdline));
+    if (cmdline == NULL)
+    {
+        ReturnLastError(pipe, L"malloc");
+        goto out;
+    }
+    openvpn_sntprintf(cmdline, cmdline_size, L"openvpn %s --msg-channel %lu",
+                      sud.options, svc_pipe);
+
+    if (!CreateEnvironmentBlock(&user_env, imp_token, FALSE))
+    {
+        ReturnLastError(pipe, L"CreateEnvironmentBlock");
+        goto out;
+    }
+
+    startup_info.cb = sizeof(startup_info);
+    startup_info.lpDesktop = L"winsta0\\default";
+    startup_info.dwFlags = STARTF_USESTDHANDLES;
+    startup_info.hStdInput = stdin_read;
+    startup_info.hStdOutput = stdout_write;
+    startup_info.hStdError = stdout_write;
+
+#ifdef UNICODE
+    exe_path = settings.exe_path;
+#else
+    WCHAR wide_path[MAX_PATH];
+    MultiByteToWideChar(CP_UTF8, 0, settings.exe_path, MAX_PATH, wide_path, MAX_PATH);
+    exe_path = wide_path;
+#endif
+
+    /* TODO: make sure HKCU is correct or call LoadUserProfile() */
+    if (!CreateProcessAsUserW(pri_token, exe_path, cmdline, &ovpn_sa, NULL, TRUE,
+                              settings.priority | CREATE_NO_WINDOW | CREATE_UNICODE_ENVIRONMENT,
+                              user_env, sud.directory, &startup_info, &proc_info))
+    {
+        ReturnLastError(pipe, L"CreateProcessAsUser");
+        goto out;
+    }
+
+    if (!RevertToSelf())
+    {
+        TerminateProcess(proc_info.hProcess, 1);
+        ReturnLastError(pipe, L"RevertToSelf");
+        goto out;
+    }
+
+    ReturnProcessId(pipe, proc_info.dwProcessId, 1, &exit_event);
+
+    CloseHandleEx(&stdout_write);
+    CloseHandleEx(&stdin_read);
+    CloseHandleEx(&svc_pipe);
+
+    DWORD input_size = WideCharToMultiByte(CP_UTF8, 0, sud.std_input, -1, NULL, 0, NULL, NULL);
+    LPSTR input = NULL;
+    if (input_size && (input = malloc(input_size)))
+    {
+        DWORD written;
+        WideCharToMultiByte(CP_UTF8, 0, sud.std_input, -1, input, input_size, NULL, NULL);
+        WriteFile(stdin_write, input, strlen(input), &written, NULL);
+        free(input);
+    }
+
+    while (TRUE)
+    {
+        DWORD bytes = PeekNamedPipeAsync(ovpn_pipe, 1, &exit_event);
+        if (bytes == 0)
+        {
+            break;
+        }
+
+        HandleMessage(ovpn_pipe, bytes, 1, &exit_event, &undo_lists);
+    }
+
+    WaitForSingleObject(proc_info.hProcess, IO_TIMEOUT);
+    GetExitCodeProcess(proc_info.hProcess, &exit_code);
+    if (exit_code == STILL_ACTIVE)
+    {
+        TerminateProcess(proc_info.hProcess, 1);
+    }
+    else if (exit_code != 0)
+    {
+        WCHAR buf[256];
+        swprintf(buf, _countof(buf),
+                 L"OpenVPN exited with error: exit code = %lu", exit_code);
+        buf[_countof(buf) - 1] =  L'\0';
+        ReturnError(pipe, ERROR_OPENVPN_STARTUP, buf, 1, &exit_event);
+    }
+    Undo(&undo_lists);
+
+out:
+    FlushFileBuffers(pipe);
+    DisconnectNamedPipe(pipe);
+
+    free(ovpn_user);
+    free(svc_user);
+    free(cmdline);
+    DestroyEnvironmentBlock(user_env);
+    FreeStartupData(&sud);
+    CloseHandleEx(&proc_info.hProcess);
+    CloseHandleEx(&proc_info.hThread);
+    CloseHandleEx(&stdin_read);
+    CloseHandleEx(&stdin_write);
+    CloseHandleEx(&stdout_write);
+    CloseHandleEx(&svc_token);
+    CloseHandleEx(&imp_token);
+    CloseHandleEx(&pri_token);
+    CloseHandleEx(&ovpn_pipe);
+    CloseHandleEx(&svc_pipe);
+    CloseHandleEx(&pipe);
+
+    return 0;
+}
+
+
+static DWORD WINAPI
+ServiceCtrlInteractive(DWORD ctrl_code, DWORD event, LPVOID data, LPVOID ctx)
+{
+    SERVICE_STATUS *status = ctx;
+    switch (ctrl_code)
+    {
+        case SERVICE_CONTROL_STOP:
+            status->dwCurrentState = SERVICE_STOP_PENDING;
+            ReportStatusToSCMgr(service, status);
+            if (exit_event)
+            {
+                SetEvent(exit_event);
+            }
+            return NO_ERROR;
+
+        case SERVICE_CONTROL_INTERROGATE:
+            return NO_ERROR;
+
+        default:
+            return ERROR_CALL_NOT_IMPLEMENTED;
+    }
+}
+
+
+static HANDLE
+CreateClientPipeInstance(VOID)
+{
+    TCHAR pipe_name[256]; /* The entire pipe name string can be up to 256 characters long according to MSDN. */
+    HANDLE pipe = NULL;
+    PACL old_dacl, new_dacl;
+    PSECURITY_DESCRIPTOR sd;
+    static EXPLICIT_ACCESS ea[2];
+    static BOOL initialized = FALSE;
+    DWORD flags = PIPE_ACCESS_DUPLEX | WRITE_DAC | FILE_FLAG_OVERLAPPED;
+
+    if (!initialized)
+    {
+        PSID everyone, anonymous;
+
+        ConvertStringSidToSid(TEXT("S-1-1-0"), &everyone);
+        ConvertStringSidToSid(TEXT("S-1-5-7"), &anonymous);
+
+        ea[0].grfAccessPermissions = FILE_GENERIC_WRITE;
+        ea[0].grfAccessMode = GRANT_ACCESS;
+        ea[0].grfInheritance = NO_INHERITANCE;
+        ea[0].Trustee.pMultipleTrustee = NULL;
+        ea[0].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
+        ea[0].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+        ea[0].Trustee.TrusteeType = TRUSTEE_IS_UNKNOWN;
+        ea[0].Trustee.ptstrName = (LPTSTR) everyone;
+
+        ea[1].grfAccessPermissions = 0;
+        ea[1].grfAccessMode = REVOKE_ACCESS;
+        ea[1].grfInheritance = NO_INHERITANCE;
+        ea[1].Trustee.pMultipleTrustee = NULL;
+        ea[1].Trustee.MultipleTrusteeOperation = NO_MULTIPLE_TRUSTEE;
+        ea[1].Trustee.TrusteeForm = TRUSTEE_IS_SID;
+        ea[1].Trustee.TrusteeType = TRUSTEE_IS_UNKNOWN;
+        ea[1].Trustee.ptstrName = (LPTSTR) anonymous;
+
+        flags |= FILE_FLAG_FIRST_PIPE_INSTANCE;
+        initialized = TRUE;
+    }
+
+    openvpn_sntprintf(pipe_name, _countof(pipe_name), TEXT("\\\\.\\pipe\\" PACKAGE "%s\\service"), service_instance);
+    pipe = CreateNamedPipe(pipe_name, flags,
+                           PIPE_TYPE_MESSAGE | PIPE_READMODE_MESSAGE,
+                           PIPE_UNLIMITED_INSTANCES, 1024, 1024, 0, NULL);
+    if (pipe == INVALID_HANDLE_VALUE)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Could not create named pipe"));
+        return INVALID_HANDLE_VALUE;
+    }
+
+    if (GetSecurityInfo(pipe, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION,
+                        NULL, NULL, &old_dacl, NULL, &sd) != ERROR_SUCCESS)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Could not get pipe security info"));
+        return CloseHandleEx(&pipe);
+    }
+
+    if (SetEntriesInAcl(2, ea, old_dacl, &new_dacl) != ERROR_SUCCESS)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Could not set entries in new acl"));
+        return CloseHandleEx(&pipe);
+    }
+
+    if (SetSecurityInfo(pipe, SE_KERNEL_OBJECT, DACL_SECURITY_INFORMATION,
+                        NULL, NULL, new_dacl, NULL) != ERROR_SUCCESS)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Could not set pipe security info"));
+        return CloseHandleEx(&pipe);
+    }
+
+    return pipe;
+}
+
+
+static DWORD
+UpdateWaitHandles(LPHANDLE *handles_ptr, LPDWORD count,
+                  HANDLE io_event, HANDLE exit_event, list_item_t *threads)
+{
+    static DWORD size = 10;
+    static LPHANDLE handles = NULL;
+    DWORD pos = 0;
+
+    if (handles == NULL)
+    {
+        handles = malloc(size * sizeof(HANDLE));
+        *handles_ptr = handles;
+        if (handles == NULL)
+        {
+            return ERROR_OUTOFMEMORY;
+        }
+    }
+
+    handles[pos++] = io_event;
+
+    if (!threads)
+    {
+        handles[pos++] = exit_event;
+    }
+
+    while (threads)
+    {
+        if (pos == size)
+        {
+            LPHANDLE tmp;
+            size += 10;
+            tmp = realloc(handles, size * sizeof(HANDLE));
+            if (tmp == NULL)
+            {
+                size -= 10;
+                *count = pos;
+                return ERROR_OUTOFMEMORY;
+            }
+            handles = tmp;
+            *handles_ptr = handles;
+        }
+        handles[pos++] = threads->data;
+        threads = threads->next;
+    }
+
+    *count = pos;
+    return NO_ERROR;
+}
+
+
+static VOID
+FreeWaitHandles(LPHANDLE h)
+{
+    free(h);
+}
+
+static BOOL
+CmpHandle(LPVOID item, LPVOID hnd)
+{
+    return item == hnd;
+}
+
+
+VOID WINAPI
+ServiceStartInteractiveOwn(DWORD dwArgc, LPTSTR *lpszArgv)
+{
+    status.dwServiceType = SERVICE_WIN32_OWN_PROCESS;
+    ServiceStartInteractive(dwArgc, lpszArgv);
+}
+
+
+VOID WINAPI
+ServiceStartInteractive(DWORD dwArgc, LPTSTR *lpszArgv)
+{
+    HANDLE pipe, io_event = NULL;
+    OVERLAPPED overlapped;
+    DWORD error = NO_ERROR;
+    list_item_t *threads = NULL;
+    PHANDLE handles = NULL;
+    DWORD handle_count;
+
+    service = RegisterServiceCtrlHandlerEx(interactive_service.name, ServiceCtrlInteractive, &status);
+    if (!service)
+    {
+        return;
+    }
+
+    status.dwCurrentState = SERVICE_START_PENDING;
+    status.dwServiceSpecificExitCode = NO_ERROR;
+    status.dwWin32ExitCode = NO_ERROR;
+    status.dwWaitHint = 3000;
+    ReportStatusToSCMgr(service, &status);
+
+    /* Read info from registry in key HKLM\SOFTWARE\OpenVPN */
+    error = GetOpenvpnSettings(&settings);
+    if (error != ERROR_SUCCESS)
+    {
+        goto out;
+    }
+
+    io_event = InitOverlapped(&overlapped);
+    exit_event = CreateEvent(NULL, TRUE, FALSE, NULL);
+    if (!exit_event || !io_event)
+    {
+        error = MsgToEventLog(M_SYSERR, TEXT("Could not create event"));
+        goto out;
+    }
+
+    rdns_semaphore = CreateSemaphoreW(NULL, 1, 1, NULL);
+    if (!rdns_semaphore)
+    {
+        error = MsgToEventLog(M_SYSERR, TEXT("Could not create semaphore for register-dns"));
+        goto out;
+    }
+
+    error = UpdateWaitHandles(&handles, &handle_count, io_event, exit_event, threads);
+    if (error != NO_ERROR)
+    {
+        goto out;
+    }
+
+    pipe = CreateClientPipeInstance();
+    if (pipe == INVALID_HANDLE_VALUE)
+    {
+        goto out;
+    }
+
+    status.dwCurrentState = SERVICE_RUNNING;
+    status.dwWaitHint = 0;
+    ReportStatusToSCMgr(service, &status);
+
+    while (TRUE)
+    {
+        if (ConnectNamedPipe(pipe, &overlapped) == FALSE
+            && GetLastError() != ERROR_PIPE_CONNECTED
+            && GetLastError() != ERROR_IO_PENDING)
+        {
+            MsgToEventLog(M_SYSERR, TEXT("Could not connect pipe"));
+            break;
+        }
+
+        error = WaitForMultipleObjects(handle_count, handles, FALSE, INFINITE);
+        if (error == WAIT_OBJECT_0)
+        {
+            /* Client connected, spawn a worker thread for it */
+            HANDLE next_pipe = CreateClientPipeInstance();
+            HANDLE thread = CreateThread(NULL, 0, RunOpenvpn, pipe, CREATE_SUSPENDED, NULL);
+            if (thread)
+            {
+                error = AddListItem(&threads, thread);
+                if (!error)
+                {
+                    error = UpdateWaitHandles(&handles, &handle_count, io_event, exit_event, threads);
+                }
+                if (error)
+                {
+                    ReturnError(pipe, error, L"Insufficient resources to service new clients", 1, &exit_event);
+                    /* Update wait handles again after removing the last worker thread */
+                    RemoveListItem(&threads, CmpHandle, thread);
+                    UpdateWaitHandles(&handles, &handle_count, io_event, exit_event, threads);
+                    TerminateThread(thread, 1);
+                    CloseHandleEx(&thread);
+                    CloseHandleEx(&pipe);
+                }
+                else
+                {
+                    ResumeThread(thread);
+                }
+            }
+            else
+            {
+                CloseHandleEx(&pipe);
+            }
+
+            ResetOverlapped(&overlapped);
+            pipe = next_pipe;
+        }
+        else
+        {
+            CancelIo(pipe);
+            if (error == WAIT_FAILED)
+            {
+                MsgToEventLog(M_SYSERR, TEXT("WaitForMultipleObjects failed"));
+                SetEvent(exit_event);
+                /* Give some time for worker threads to exit and then terminate */
+                Sleep(1000);
+                break;
+            }
+            if (!threads)
+            {
+                /* exit event signaled */
+                CloseHandleEx(&pipe);
+                ResetEvent(exit_event);
+                error = NO_ERROR;
+                break;
+            }
+
+            /* Worker thread ended */
+            HANDLE thread = RemoveListItem(&threads, CmpHandle, handles[error]);
+            UpdateWaitHandles(&handles, &handle_count, io_event, exit_event, threads);
+            CloseHandleEx(&thread);
+        }
+    }
+
+out:
+    FreeWaitHandles(handles);
+    CloseHandleEx(&io_event);
+    CloseHandleEx(&exit_event);
+    CloseHandleEx(&rdns_semaphore);
+
+    status.dwCurrentState = SERVICE_STOPPED;
+    status.dwWin32ExitCode = error;
+    ReportStatusToSCMgr(service, &status);
+}
diff --git a/src/openvpnserv/openvpnserv.vcxproj b/src/openvpnserv/openvpnserv.vcxproj
new file mode 100644
index 0000000..655d80c
--- /dev/null
+++ b/src/openvpnserv/openvpnserv.vcxproj
@@ -0,0 +1,114 @@
+﻿<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="12.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|Win32">
+      <Configuration>Debug</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|Win32">
+      <Configuration>Release</Configuration>
+      <Platform>Win32</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{9C91EE0B-817D-420A-A1E6-15A5A9D98BAD}</ProjectGuid>
+    <RootNamespace>openvpnserv</RootNamespace>
+    <Keyword>Win32Proj</Keyword>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <CharacterSet>MultiByte</CharacterSet>
+    <WholeProgramOptimization>true</WholeProgramOptimization>
+    <PlatformToolset>v120</PlatformToolset>
+  </PropertyGroup>
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="Configuration">
+    <ConfigurationType>Application</ConfigurationType>
+    <CharacterSet>MultiByte</CharacterSet>
+    <PlatformToolset>v120</PlatformToolset>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'" Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <ImportGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'" Label="PropertySheets">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup>
+    <_ProjectFileVersion>10.0.30319.1</_ProjectFileVersion>
+    <OutDir Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">$(SolutionDir)$(Platform)-Output\$(Configuration)\</OutDir>
+    <IntDir Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">$(Configuration)\</IntDir>
+    <LinkIncremental Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">true</LinkIncremental>
+    <OutDir Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">$(SolutionDir)$(Platform)-Output\$(Configuration)\</OutDir>
+    <IntDir Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">$(Configuration)\</IntDir>
+    <LinkIncremental Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">false</LinkIncremental>
+  </PropertyGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Debug|Win32'">
+    <ClCompile>
+      <Optimization>Disabled</Optimization>
+      <AdditionalIncludeDirectories>$(SOURCEBASE);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WIN32;_DEBUG;_CONSOLE;$(CPPFLAGS);%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <MinimalRebuild>true</MinimalRebuild>
+      <BasicRuntimeChecks>EnableFastChecks</BasicRuntimeChecks>
+      <RuntimeLibrary>MultiThreadedDebugDLL</RuntimeLibrary>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <DebugInformationFormat>EditAndContinue</DebugInformationFormat>
+    </ClCompile>
+    <ResourceCompile>
+      <AdditionalIncludeDirectories>$(SOURCEBASE);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+    </ResourceCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+      <TargetMachine>MachineX86</TargetMachine>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|Win32'">
+    <ClCompile>
+      <Optimization>MaxSpeed</Optimization>
+      <IntrinsicFunctions>true</IntrinsicFunctions>
+      <AdditionalIncludeDirectories>$(SOURCEBASE);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+      <PreprocessorDefinitions>WIN32;NDEBUG;_CONSOLE;$(CPPFLAGS);%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <RuntimeLibrary>MultiThreadedDLL</RuntimeLibrary>
+      <FunctionLevelLinking>true</FunctionLevelLinking>
+      <PrecompiledHeader>
+      </PrecompiledHeader>
+      <WarningLevel>Level3</WarningLevel>
+      <DebugInformationFormat>ProgramDatabase</DebugInformationFormat>
+    </ClCompile>
+    <ResourceCompile>
+      <AdditionalIncludeDirectories>$(SOURCEBASE);%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+    </ResourceCompile>
+    <Link>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+      <SubSystem>Console</SubSystem>
+      <OptimizeReferences>true</OptimizeReferences>
+      <EnableCOMDATFolding>true</EnableCOMDATFolding>
+      <TargetMachine>MachineX86</TargetMachine>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="openvpnserv.c" />
+    <ClCompile Include="service.c" />
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="service.h" />
+  </ItemGroup>
+  <ItemGroup>
+    <ResourceCompile Include="openvpnserv_resources.rc" />
+  </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\..\build\msvc\msvc-generate\msvc-generate.vcxproj">
+      <Project>{8598c2c8-34c4-47a1-99b0-7c295a890615}</Project>
+      <ReferenceOutputAssembly>false</ReferenceOutputAssembly>
+    </ProjectReference>
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>
diff --git a/src/openvpnserv/openvpnserv.vcxproj.filters b/src/openvpnserv/openvpnserv.vcxproj.filters
new file mode 100644
index 0000000..a6f8ecc
--- /dev/null
+++ b/src/openvpnserv/openvpnserv.vcxproj.filters
@@ -0,0 +1,35 @@
+﻿<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup>
+    <Filter Include="Source Files">
+      <UniqueIdentifier>{4FC737F1-C7A5-4376-A066-2A32D752A2FF}</UniqueIdentifier>
+      <Extensions>cpp;c;cc;cxx;def;odl;idl;hpj;bat;asm;asmx</Extensions>
+    </Filter>
+    <Filter Include="Header Files">
+      <UniqueIdentifier>{93995380-89BD-4b04-88EB-625FBE52EBFB}</UniqueIdentifier>
+      <Extensions>h;hpp;hxx;hm;inl;inc;xsd</Extensions>
+    </Filter>
+    <Filter Include="Resource Files">
+      <UniqueIdentifier>{67DA6AB6-F800-4c08-8B7A-83BB121AAD01}</UniqueIdentifier>
+      <Extensions>rc;ico;cur;bmp;dlg;rc2;rct;bin;rgs;gif;jpg;jpeg;jpe;resx;tiff;tif;png;wav</Extensions>
+    </Filter>
+  </ItemGroup>
+  <ItemGroup>
+    <ClCompile Include="openvpnserv.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+    <ClCompile Include="service.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
+  </ItemGroup>
+  <ItemGroup>
+    <ClInclude Include="service.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
+  </ItemGroup>
+  <ItemGroup>
+    <ResourceCompile Include="openvpnserv_resources.rc">
+      <Filter>Resource Files</Filter>
+    </ResourceCompile>
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/src/openvpnserv/openvpnserv_resources.rc b/src/openvpnserv/openvpnserv_resources.rc
new file mode 100644
index 0000000..4ea453e
--- /dev/null
+++ b/src/openvpnserv/openvpnserv_resources.rc
@@ -0,0 +1,43 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#else
+#include <config-msvc-version.h>
+#endif
+#include <winresrc.h>
+
+#pragma code_page(65001) /* UTF8 */
+
+LANGUAGE LANG_NEUTRAL, SUBLANG_NEUTRAL
+
+VS_VERSION_INFO VERSIONINFO
+ FILEVERSION OPENVPN_VERSION_RESOURCE
+ PRODUCTVERSION OPENVPN_VERSION_RESOURCE
+ FILEFLAGSMASK 0x3fL
+#ifdef _DEBUG
+ FILEFLAGS 0x1L
+#else
+ FILEFLAGS 0x0L
+#endif
+ FILEOS 0x40004L
+ FILETYPE VFT_APP
+ FILESUBTYPE 0x0L
+BEGIN
+    BLOCK "StringFileInfo"
+    BEGIN
+        BLOCK "040904b0"
+        BEGIN
+            VALUE "CompanyName", "The OpenVPN Project"
+            VALUE "FileDescription", "OpenVPN Service"
+            VALUE "FileVersion", PACKAGE_VERSION ".0"
+            VALUE "InternalName", "OpenVPN"
+            VALUE "LegalCopyright", "Copyright © The OpenVPN Project" 
+            VALUE "OriginalFilename", "openvpnserv.exe"
+            VALUE "ProductName", "OpenVPN"
+            VALUE "ProductVersion", PACKAGE_VERSION ".0"
+        END
+    END
+    BLOCK "VarFileInfo"
+    BEGIN
+        VALUE "Translation", 0x409, 1200
+    END
+END
diff --git a/src/openvpnserv/service.c b/src/openvpnserv/service.c
new file mode 100644
index 0000000..7157bea
--- /dev/null
+++ b/src/openvpnserv/service.c
@@ -0,0 +1,310 @@
+/*
+ * THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
+ * ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED
+ * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
+ * PARTICULAR PURPOSE.
+ *
+ * Copyright (C) 1993 - 2000.  Microsoft Corporation.  All rights reserved.
+ *                      2013 Heiko Hund <heiko.hund@sophos.com>
+ */
+
+#include "service.h"
+
+#include <windows.h>
+#include <stdio.h>
+#include <process.h>
+
+
+openvpn_service_t openvpn_service[_service_max];
+
+
+BOOL
+ReportStatusToSCMgr(SERVICE_STATUS_HANDLE service, SERVICE_STATUS *status)
+{
+    static DWORD dwCheckPoint = 1;
+    BOOL res = TRUE;
+
+    if (status->dwCurrentState == SERVICE_START_PENDING)
+    {
+        status->dwControlsAccepted = 0;
+    }
+    else
+    {
+        status->dwControlsAccepted = SERVICE_ACCEPT_STOP;
+    }
+
+    if (status->dwCurrentState == SERVICE_RUNNING
+        || status->dwCurrentState == SERVICE_STOPPED)
+    {
+        status->dwCheckPoint = 0;
+    }
+    else
+    {
+        status->dwCheckPoint = dwCheckPoint++;
+    }
+
+    /* Report the status of the service to the service control manager. */
+    res = SetServiceStatus(service, status);
+    if (!res)
+    {
+        MsgToEventLog(MSG_FLAGS_ERROR, TEXT("SetServiceStatus"));
+    }
+
+    return res;
+}
+
+static int
+CmdInstallServices()
+{
+    SC_HANDLE service;
+    SC_HANDLE svc_ctl_mgr;
+    TCHAR path[512];
+    int i, ret = _service_max;
+
+    if (GetModuleFileName(NULL, path + 1, 510) == 0)
+    {
+        _tprintf(TEXT("Unable to install service - %s\n"), GetLastErrorText());
+        return 1;
+    }
+
+    path[0] = TEXT('\"');
+    _tcscat(path, TEXT("\""));
+
+    svc_ctl_mgr = OpenSCManager(NULL, NULL, SC_MANAGER_CONNECT | SC_MANAGER_CREATE_SERVICE);
+    if (svc_ctl_mgr == NULL)
+    {
+        _tprintf(TEXT("OpenSCManager failed - %s\n"), GetLastErrorText());
+        return 1;
+    }
+
+    for (i = 0; i < _service_max; i++)
+    {
+        service = CreateService(svc_ctl_mgr,
+                                openvpn_service[i].name,
+                                openvpn_service[i].display_name,
+                                SERVICE_QUERY_STATUS,
+                                SERVICE_WIN32_SHARE_PROCESS,
+                                openvpn_service[i].start_type,
+                                SERVICE_ERROR_NORMAL,
+                                path, NULL, NULL,
+                                openvpn_service[i].dependencies,
+                                NULL, NULL);
+        if (service)
+        {
+            _tprintf(TEXT("%s installed.\n"), openvpn_service[i].display_name);
+            CloseServiceHandle(service);
+            --ret;
+        }
+        else
+        {
+            _tprintf(TEXT("CreateService failed - %s\n"), GetLastErrorText());
+        }
+    }
+
+    CloseServiceHandle(svc_ctl_mgr);
+    return ret;
+}
+
+
+static int
+CmdStartService(openvpn_service_type type)
+{
+    int ret = 1;
+    SC_HANDLE svc_ctl_mgr;
+    SC_HANDLE service;
+
+    svc_ctl_mgr = OpenSCManager(NULL, NULL, SC_MANAGER_ALL_ACCESS);
+    if (svc_ctl_mgr == NULL)
+    {
+        _tprintf(TEXT("OpenSCManager failed - %s\n"), GetLastErrorText());
+        return 1;
+    }
+
+    service = OpenService(svc_ctl_mgr, openvpn_service[type].name, SERVICE_ALL_ACCESS);
+    if (service)
+    {
+        if (StartService(service, 0, NULL))
+        {
+            _tprintf(TEXT("Service Started\n"));
+            ret = 0;
+        }
+        else
+        {
+            _tprintf(TEXT("StartService failed - %s\n"), GetLastErrorText());
+        }
+
+        CloseServiceHandle(service);
+    }
+    else
+    {
+        _tprintf(TEXT("OpenService failed - %s\n"), GetLastErrorText());
+    }
+
+    CloseServiceHandle(svc_ctl_mgr);
+    return ret;
+}
+
+
+static int
+CmdRemoveServices()
+{
+    SC_HANDLE service;
+    SC_HANDLE svc_ctl_mgr;
+    SERVICE_STATUS status;
+    int i, ret = _service_max;
+
+    svc_ctl_mgr = OpenSCManager(NULL, NULL, SC_MANAGER_CONNECT);
+    if (svc_ctl_mgr == NULL)
+    {
+        _tprintf(TEXT("OpenSCManager failed - %s\n"), GetLastErrorText());
+        return 1;
+    }
+
+    for (i = 0; i < _service_max; i++)
+    {
+        openvpn_service_t *ovpn_svc = &openvpn_service[i];
+        service = OpenService(svc_ctl_mgr, ovpn_svc->name,
+                              DELETE | SERVICE_STOP | SERVICE_QUERY_STATUS);
+        if (service == NULL)
+        {
+            _tprintf(TEXT("OpenService failed - %s\n"), GetLastErrorText());
+            goto out;
+        }
+
+        /* try to stop the service */
+        if (ControlService(service, SERVICE_CONTROL_STOP, &status))
+        {
+            _tprintf(TEXT("Stopping %s."), ovpn_svc->display_name);
+            Sleep(1000);
+
+            while (QueryServiceStatus(service, &status))
+            {
+                if (status.dwCurrentState == SERVICE_STOP_PENDING)
+                {
+                    _tprintf(TEXT("."));
+                    Sleep(1000);
+                }
+                else
+                {
+                    break;
+                }
+            }
+
+            if (status.dwCurrentState == SERVICE_STOPPED)
+            {
+                _tprintf(TEXT("\n%s stopped.\n"), ovpn_svc->display_name);
+            }
+            else
+            {
+                _tprintf(TEXT("\n%s failed to stop.\n"), ovpn_svc->display_name);
+            }
+        }
+
+        /* now remove the service */
+        if (DeleteService(service))
+        {
+            _tprintf(TEXT("%s removed.\n"), ovpn_svc->display_name);
+            --ret;
+        }
+        else
+        {
+            _tprintf(TEXT("DeleteService failed - %s\n"), GetLastErrorText());
+        }
+
+        CloseServiceHandle(service);
+    }
+
+out:
+    CloseServiceHandle(svc_ctl_mgr);
+    return ret;
+}
+
+
+int
+_tmain(int argc, TCHAR *argv[])
+{
+    /*
+     * Automatic + Interactive service (as a SERVICE_WIN32_SHARE_PROCESS)
+     * This is the default.
+     */
+    const SERVICE_TABLE_ENTRY dispatchTable_shared[] = {
+        { automatic_service.name, ServiceStartAutomatic },
+        { interactive_service.name, ServiceStartInteractive },
+        { NULL, NULL }
+    };
+
+    /* Automatic service only (as a SERVICE_WIN32_OWN_PROCESS) */
+    const SERVICE_TABLE_ENTRY dispatchTable_automatic[] = {
+        { TEXT(""), ServiceStartAutomaticOwn },
+        { NULL, NULL }
+    };
+
+    /* Interactive service only (as a SERVICE_WIN32_OWN_PROCESS) */
+    const SERVICE_TABLE_ENTRY dispatchTable_interactive[] = {
+        { TEXT(""), ServiceStartInteractiveOwn },
+        { NULL, NULL }
+    };
+
+    const SERVICE_TABLE_ENTRY *dispatchTable = dispatchTable_shared;
+
+    openvpn_service[0] = automatic_service;
+    openvpn_service[1] = interactive_service;
+
+    for (int i = 1; i < argc; i++)
+    {
+        if (*argv[i] == TEXT('-') || *argv[i] == TEXT('/'))
+        {
+            if (_tcsicmp(TEXT("install"), argv[i] + 1) == 0)
+            {
+                return CmdInstallServices();
+            }
+            else if (_tcsicmp(TEXT("remove"), argv[i] + 1) == 0)
+            {
+                return CmdRemoveServices();
+            }
+            else if (_tcsicmp(TEXT("start"), argv[i] + 1) == 0)
+            {
+                BOOL is_auto = argc < i + 2 || _tcsicmp(TEXT("interactive"), argv[i + 1]) != 0;
+                return CmdStartService(is_auto ? automatic : interactive);
+            }
+            else if (argc > i + 2 && _tcsicmp(TEXT("instance"), argv[i] + 1) == 0)
+            {
+                dispatchTable = _tcsicmp(TEXT("interactive"), argv[i + 1]) != 0 ?
+                    dispatchTable_automatic :
+                    dispatchTable_interactive;
+
+                service_instance = argv[i + 2];
+                i += 2;
+            }
+            else
+            {
+                _tprintf(TEXT("%s -install        to install the services\n"), APPNAME);
+                _tprintf(TEXT("%s -start <name>   to start a service (\"automatic\" or \"interactive\")\n"), APPNAME);
+                _tprintf(TEXT("%s -remove         to remove the services\n"), APPNAME);
+
+                _tprintf(TEXT("\nService run-time parameters:\n"));
+                _tprintf(TEXT("-instance <name> <id>\n")
+                         TEXT("   Runs the service as an alternate instance. <name> can be \"automatic\" or\n")
+                         TEXT("   \"interactive\". The service settings will be loaded from\n")
+                         TEXT("   HKLM\\Software\\" PACKAGE_NAME "<id> registry key, and the interactive service will accept\n")
+                         TEXT("   requests on \\\\.\\pipe\\" PACKAGE "<id>\\service named pipe.\n"));
+
+                return 0;
+            }
+        }
+    }
+
+    /* If it doesn't match any of the above parameters
+     * the service control manager may be starting the service
+     * so we must call StartServiceCtrlDispatcher
+     */
+    _tprintf(TEXT("\nStartServiceCtrlDispatcher being called.\n"));
+    _tprintf(TEXT("This may take several seconds. Please wait.\n"));
+
+    if (!StartServiceCtrlDispatcher(dispatchTable))
+    {
+        MsgToEventLog(MSG_FLAGS_ERROR, TEXT("StartServiceCtrlDispatcher failed."));
+    }
+
+    return 0;
+}
diff --git a/src/openvpnserv/service.h b/src/openvpnserv/service.h
new file mode 100644
index 0000000..23b105f
--- /dev/null
+++ b/src/openvpnserv/service.h
@@ -0,0 +1,102 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2013-2018 Heiko Hund <heiko.hund@sophos.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _SERVICE_H
+#define _SERVICE_H
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include <windows.h>
+#include <stdlib.h>
+#include <tchar.h>
+
+#define APPNAME  TEXT(PACKAGE "serv")
+#define SERVICE_DEPENDENCIES  TAP_WIN_COMPONENT_ID "\0Dhcp\0\0"
+
+/*
+ * Message handling
+ */
+#define MSG_FLAGS_ERROR     (1<<0)
+#define MSG_FLAGS_SYS_CODE  (1<<1)
+#define M_INFO    (0)                                  /* informational */
+#define M_SYSERR  (MSG_FLAGS_ERROR|MSG_FLAGS_SYS_CODE) /* error + system code */
+#define M_ERR     (MSG_FLAGS_ERROR)                    /* error */
+
+typedef enum {
+    automatic,
+    interactive,
+    _service_max
+} openvpn_service_type;
+
+typedef struct {
+    openvpn_service_type type;
+    TCHAR *name;
+    TCHAR *display_name;
+    TCHAR *dependencies;
+    DWORD start_type;
+} openvpn_service_t;
+
+#define MAX_NAME 256
+typedef struct {
+    TCHAR exe_path[MAX_PATH];
+    TCHAR config_dir[MAX_PATH];
+    TCHAR ext_string[16];
+    TCHAR log_dir[MAX_PATH];
+    TCHAR ovpn_admin_group[MAX_NAME];
+    DWORD priority;
+    BOOL append;
+} settings_t;
+
+extern openvpn_service_t automatic_service;
+extern openvpn_service_t interactive_service;
+extern LPCTSTR service_instance;
+
+VOID WINAPI ServiceStartAutomaticOwn(DWORD argc, LPTSTR *argv);
+VOID WINAPI ServiceStartAutomatic(DWORD argc, LPTSTR *argv);
+
+VOID WINAPI ServiceStartInteractiveOwn(DWORD argc, LPTSTR *argv);
+VOID WINAPI ServiceStartInteractive(DWORD argc, LPTSTR *argv);
+
+int openvpn_vsntprintf(LPTSTR str, size_t size, LPCTSTR format, va_list arglist);
+
+int openvpn_sntprintf(LPTSTR str, size_t size, LPCTSTR format, ...);
+
+DWORD GetOpenvpnSettings(settings_t *s);
+
+BOOL ReportStatusToSCMgr(SERVICE_STATUS_HANDLE service, SERVICE_STATUS *status);
+
+LPCTSTR GetLastErrorText();
+
+DWORD MsgToEventLog(DWORD flags, LPCTSTR lpszMsg, ...);
+
+/* Convert a utf8 string to utf16. Caller should free the result */
+wchar_t *utf8to16(const char *utf8);
+
+/* return windows system directory as a pointer to a static string */
+const wchar_t *get_win_sys_path(void);
+
+#endif /* ifndef _SERVICE_H */
diff --git a/src/openvpnserv/validate.c b/src/openvpnserv/validate.c
new file mode 100644
index 0000000..d35938c
--- /dev/null
+++ b/src/openvpnserv/validate.c
@@ -0,0 +1,345 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "validate.h"
+
+#include <lmaccess.h>
+#include <shlwapi.h>
+#include <lm.h>
+
+static const WCHAR *white_list[] =
+{
+    L"auth-retry",
+    L"config",
+    L"log",
+    L"log-append",
+    L"management",
+    L"management-forget-disconnect",
+    L"management-hold",
+    L"management-query-passwords",
+    L"management-query-proxy",
+    L"management-signal",
+    L"management-up-down",
+    L"mute",
+    L"setenv",
+    L"service",
+    L"verb",
+    L"pull-filter",
+    L"script-security",
+
+    NULL                                /* last value */
+};
+
+static BOOL IsUserInGroup(PSID sid, const PTOKEN_GROUPS groups, const WCHAR *group_name);
+static PTOKEN_GROUPS GetTokenGroups(const HANDLE token);
+
+/*
+ * Check workdir\fname is inside config_dir
+ * The logic here is simple: we may reject some valid paths if ..\ is in any of the strings
+ */
+static BOOL
+CheckConfigPath(const WCHAR *workdir, const WCHAR *fname, const settings_t *s)
+{
+    WCHAR tmp[MAX_PATH];
+    const WCHAR *config_file = NULL;
+    const WCHAR *config_dir = NULL;
+
+    /* convert fname to full path */
+    if (PathIsRelativeW(fname) )
+    {
+        swprintf(tmp, _countof(tmp), L"%s\\%s", workdir, fname);
+        tmp[_countof(tmp)-1] = L'\0';
+        config_file = tmp;
+    }
+    else
+    {
+        config_file = fname;
+    }
+
+#ifdef UNICODE
+    config_dir = s->config_dir;
+#else
+    if (MultiByteToWideChar(CP_UTF8, 0, s->config_dir, -1, widepath, MAX_PATH) == 0)
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Failed to convert config_dir name to WideChar"));
+        return FALSE;
+    }
+    config_dir = widepath;
+#endif
+
+    if (wcsncmp(config_dir, config_file, wcslen(config_dir)) == 0
+        && wcsstr(config_file + wcslen(config_dir), L"..") == NULL)
+    {
+        return TRUE;
+    }
+
+    return FALSE;
+}
+
+
+/*
+ * A simple linear search meant for a small wchar_t *array.
+ * Returns index to the item if found, -1 otherwise.
+ */
+static int
+OptionLookup(const WCHAR *name, const WCHAR *white_list[])
+{
+    int i;
+
+    for (i = 0; white_list[i]; i++)
+    {
+        if (wcscmp(white_list[i], name) == 0)
+        {
+            return i;
+        }
+    }
+
+    return -1;
+}
+
+/*
+ * The Administrators group may be localized or renamed by admins.
+ * Get the local name of the group using the SID.
+ */
+static BOOL
+GetBuiltinAdminGroupName(WCHAR *name, DWORD nlen)
+{
+    BOOL b = FALSE;
+    PSID admin_sid = NULL;
+    DWORD sid_size = SECURITY_MAX_SID_SIZE;
+    SID_NAME_USE snu;
+
+    WCHAR domain[MAX_NAME];
+    DWORD dlen = _countof(domain);
+
+    admin_sid = malloc(sid_size);
+    if (!admin_sid)
+    {
+        return FALSE;
+    }
+
+    b = CreateWellKnownSid(WinBuiltinAdministratorsSid, NULL, admin_sid,  &sid_size);
+    if (b)
+    {
+        b = LookupAccountSidW(NULL, admin_sid, name, &nlen, domain, &dlen, &snu);
+    }
+
+    free(admin_sid);
+
+    return b;
+}
+
+/*
+ * Check whether user is a member of Administrators group or
+ * the group specified in ovpn_admin_group
+ */
+BOOL
+IsAuthorizedUser(PSID sid, const HANDLE token, const WCHAR *ovpn_admin_group)
+{
+    const WCHAR *admin_group[2];
+    WCHAR username[MAX_NAME];
+    WCHAR domain[MAX_NAME];
+    WCHAR sysadmin_group[MAX_NAME];
+    DWORD len = MAX_NAME;
+    BOOL ret = FALSE;
+    SID_NAME_USE sid_type;
+
+    /* Get username */
+    if (!LookupAccountSidW(NULL, sid, username, &len, domain, &len, &sid_type))
+    {
+        MsgToEventLog(M_SYSERR, TEXT("LookupAccountSid"));
+        /* not fatal as this is now used only for logging */
+        username[0] = '\0';
+        domain[0] = '\0';
+    }
+
+    if (GetBuiltinAdminGroupName(sysadmin_group, _countof(sysadmin_group)))
+    {
+        admin_group[0] = sysadmin_group;
+    }
+    else
+    {
+        MsgToEventLog(M_SYSERR, TEXT("Failed to get the name of Administrators group. Using the default."));
+        /* use the default value */
+        admin_group[0] = SYSTEM_ADMIN_GROUP;
+    }
+    admin_group[1] = ovpn_admin_group;
+
+    PTOKEN_GROUPS token_groups = GetTokenGroups(token);
+    for (int i = 0; i < 2; ++i)
+    {
+        ret = IsUserInGroup(sid, token_groups, admin_group[i]);
+        if (ret)
+        {
+            MsgToEventLog(M_INFO, TEXT("Authorizing user '%s@%s' by virtue of membership in group '%s'"),
+                          username, domain, admin_group[i]);
+            goto out;
+        }
+    }
+
+out:
+    free(token_groups);
+    return ret;
+}
+
+/**
+ * Get a list of groups in token.
+ * Returns a pointer to TOKEN_GROUPS struct or NULL on error.
+ * The caller should free the returned pointer.
+ */
+static PTOKEN_GROUPS
+GetTokenGroups(const HANDLE token)
+{
+    PTOKEN_GROUPS groups = NULL;
+    DWORD buf_size = 0;
+
+    if (!GetTokenInformation(token, TokenGroups, groups, buf_size, &buf_size)
+        && GetLastError() == ERROR_INSUFFICIENT_BUFFER)
+    {
+        groups = malloc(buf_size);
+    }
+    if (!groups)
+    {
+        MsgToEventLog(M_SYSERR, L"GetTokenGroups");
+    }
+    else if (!GetTokenInformation(token, TokenGroups, groups, buf_size, &buf_size))
+    {
+        MsgToEventLog(M_SYSERR, L"GetTokenInformation");
+        free(groups);
+    }
+    return groups;
+}
+
+/*
+ * Find SID from name
+ *
+ * On input sid buffer should have space for at least sid_size bytes.
+ * Returns true on success, false on failure.
+ * Suggest: in caller allocate sid to hold SECURITY_MAX_SID_SIZE bytes
+ */
+static BOOL
+LookupSID(const WCHAR *name, PSID sid, DWORD sid_size)
+{
+    SID_NAME_USE su;
+    WCHAR domain[MAX_NAME];
+    DWORD dlen = _countof(domain);
+
+    if (!LookupAccountName(NULL, name, sid, &sid_size, domain, &dlen, &su))
+    {
+        return FALSE; /* not fatal as the group may not exist */
+    }
+    return TRUE;
+}
+
+/**
+ * User is in group if the token groups contain the SID of the group
+ * of if the user is a direct member of the group. The latter check
+ * catches dynamic changes in group membership in the local user
+ * database not reflected in the token.
+ * If token_groups or sid is NULL the corresponding check is skipped.
+ *
+ * Using sid and list of groups in token avoids reference to domains so that
+ * this could be completed without access to a Domain Controller.
+ *
+ * Returns true if the user is in the group, false otherwise.
+ */
+static BOOL
+IsUserInGroup(PSID sid, const PTOKEN_GROUPS token_groups, const WCHAR *group_name)
+{
+    BOOL ret = FALSE;
+    DWORD_PTR resume = 0;
+    DWORD err;
+    BYTE grp_sid[SECURITY_MAX_SID_SIZE];
+    int nloop = 0; /* a counter used to not get stuck in the do .. while() */
+
+    /* first check in the token groups */
+    if (token_groups && LookupSID(group_name, (PSID) grp_sid, _countof(grp_sid)))
+    {
+        for (DWORD i = 0; i < token_groups->GroupCount; ++i)
+        {
+            if (EqualSid((PSID) grp_sid, token_groups->Groups[i].Sid))
+            {
+                return TRUE;
+            }
+        }
+    }
+
+    /* check user's SID is a member of the group */
+    if (!sid)
+    {
+        return FALSE;
+    }
+    do
+    {
+        DWORD nread, nmax;
+        LOCALGROUP_MEMBERS_INFO_0 *members = NULL;
+        err = NetLocalGroupGetMembers(NULL, group_name, 0, (LPBYTE *) &members,
+                                      MAX_PREFERRED_LENGTH, &nread, &nmax, &resume);
+        if ((err != NERR_Success && err != ERROR_MORE_DATA))
+        {
+            break;
+        }
+        /* If a match is already found, ret == TRUE and the loop is skipped */
+        for (int i = 0; i < nread && !ret; ++i)
+        {
+            ret = EqualSid(members[i].lgrmi0_sid, sid);
+        }
+        NetApiBufferFree(members);
+    /* MSDN says the lookup should always iterate until err != ERROR_MORE_DATA */
+    } while (err == ERROR_MORE_DATA && nloop++ < 100);
+
+    if (err != NERR_Success && err != NERR_GroupNotFound)
+    {
+        SetLastError(err);
+        MsgToEventLog(M_SYSERR, TEXT("In NetLocalGroupGetMembers for group '%s'"), group_name);
+    }
+
+    return ret;
+}
+
+/*
+ * Check whether option argv[0] is white-listed. If argv[0] == "--config",
+ * also check that argv[1], if present, passes CheckConfigPath().
+ * The caller should set argc to the number of valid elements in argv[] array.
+ */
+BOOL
+CheckOption(const WCHAR *workdir, int argc, WCHAR *argv[], const settings_t *s)
+{
+    /* Do not modify argv or *argv -- ideally it should be const WCHAR *const *, but alas...*/
+
+    if (wcscmp(argv[0], L"--config") == 0
+        && argc > 1
+        && !CheckConfigPath(workdir, argv[1], s)
+        )
+    {
+        return FALSE;
+    }
+
+    /* option name starts at 2 characters from argv[i] */
+    if (OptionLookup(argv[0] + 2, white_list) == -1)   /* not found */
+    {
+        return FALSE;
+    }
+
+    return TRUE;
+}
diff --git a/src/openvpnserv/validate.h b/src/openvpnserv/validate.h
new file mode 100644
index 0000000..cc443e6
--- /dev/null
+++ b/src/openvpnserv/validate.h
@@ -0,0 +1,47 @@
+
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2016 Selva Nair <selva.nair@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef VALIDATE_H
+#define VALIDATE_H
+
+#include "service.h"
+
+/* Authorized groups who can use any options and config locations */
+#define SYSTEM_ADMIN_GROUP TEXT("Administrators")
+#define OVPN_ADMIN_GROUP TEXT("OpenVPN Administrators")
+/* The last one may be reset in registry: HKLM\Software\OpenVPN\ovpn_admin_group */
+
+BOOL
+IsAuthorizedUser(PSID sid, const HANDLE token, const WCHAR *ovpn_admin_group);
+
+BOOL
+CheckOption(const WCHAR *workdir, int narg, WCHAR *argv[], const settings_t *s);
+
+static inline BOOL
+IsOption(const WCHAR *o)
+{
+    return (wcsncmp(o, L"--", 2) == 0);
+}
+
+#endif /* ifndef VALIDATE_H */
diff --git a/src/plugins/Makefile.am b/src/plugins/Makefile.am
new file mode 100644
index 0000000..b1358d9
--- /dev/null
+++ b/src/plugins/Makefile.am
@@ -0,0 +1,15 @@
+#
+#  OpenVPN -- An application to securely tunnel IP networks
+#             over a single UDP port, with support for SSL/TLS-based
+#             session authentication and key exchange,
+#             packet encryption, packet authentication, and
+#             packet compression.
+#
+#  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+#  Copyright (C) 2006-2012 Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in
+
+SUBDIRS = down-root
diff --git a/src/plugins/down-root/Makefile.am b/src/plugins/down-root/Makefile.am
new file mode 100644
index 0000000..7ca5a4e
--- /dev/null
+++ b/src/plugins/down-root/Makefile.am
@@ -0,0 +1,24 @@
+#
+#  OpenVPN (TM) Down Root Plugin -- OpenVPN Plugin
+#
+#  Copyright (C) 2012      Alon Bar-Lev <alon.barlev@gmail.com>
+#
+
+MAINTAINERCLEANFILES = \
+	$(srcdir)/Makefile.in
+
+AM_CFLAGS = \
+	-I$(top_srcdir)/include \
+	$(OPTIONAL_CRYPTO_CFLAGS)
+
+if ENABLE_PLUGIN_DOWN_ROOT
+plugin_LTLIBRARIES = openvpn-plugin-down-root.la
+dist_doc_DATA = README.down-root
+endif
+
+openvpn_plugin_down_root_la_SOURCES = \
+	down-root.c \
+	down-root.exports
+openvpn_plugin_down_root_la_LDFLAGS = $(AM_LDFLAGS) \
+	-export-symbols "$(srcdir)/down-root.exports" \
+	-module -shared -avoid-version -no-undefined
diff --git a/src/plugins/down-root/README.down-root b/src/plugins/down-root/README.down-root
new file mode 100644
index 0000000..d337ffe
--- /dev/null
+++ b/src/plugins/down-root/README.down-root
@@ -0,0 +1,29 @@
+down-root -- an OpenVPN Plugin Module
+
+SYNOPSIS
+
+The down-root module allows an OpenVPN configuration to
+call a down script with root privileges, even when privileges
+have been dropped using --user/--group/--chroot.
+
+This module uses a split privilege execution model which will
+fork() before OpenVPN drops root privileges, at the point where
+the --up script is usually called.  The module will then remain
+in a wait state until it receives a message from OpenVPN via
+pipe to execute the down script.  Thus, the down script will be
+run in the same execution environment as the up script.
+
+BUILD
+
+Build this module with the "make" command.  The plugin
+module will be named openvpn-down-root.so
+
+USAGE
+
+To use this module, add to your OpenVPN config file:
+
+  plugin openvpn-down-root.so "command ..."
+
+CAVEATS
+
+This module will only work on *nix systems, not Windows.
diff --git a/src/plugins/down-root/down-root.c b/src/plugins/down-root/down-root.c
new file mode 100644
index 0000000..c5e5023
--- /dev/null
+++ b/src/plugins/down-root/down-root.c
@@ -0,0 +1,576 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net>
+ *  Copyright (C) 2013      David Sommerseth <davids@redhat.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along
+ *  with this program; if not, write to the Free Software Foundation, Inc.,
+ *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * OpenVPN plugin module to do privileged down-script execution.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <syslog.h>
+#include <errno.h>
+#include <err.h>
+
+#include <openvpn-plugin.h>
+
+#define DEBUG(verb) ((verb) >= 7)
+
+/* Command codes for foreground -> background communication */
+#define COMMAND_RUN_SCRIPT 1
+#define COMMAND_EXIT       2
+
+/* Response codes for background -> foreground communication */
+#define RESPONSE_INIT_SUCCEEDED   10
+#define RESPONSE_INIT_FAILED      11
+#define RESPONSE_SCRIPT_SUCCEEDED 12
+#define RESPONSE_SCRIPT_FAILED    13
+
+/* Background process function */
+static void down_root_server(const int fd, char *const *argv, char *const *envp, const int verb);
+
+/*
+ * Plugin state, used by foreground
+ */
+struct down_root_context
+{
+    /* Foreground's socket to background process */
+    int foreground_fd;
+
+    /* Process ID of background process */
+    pid_t background_pid;
+
+    /* Verbosity level of OpenVPN */
+    int verb;
+
+    /* down command */
+    char **command;
+};
+
+/*
+ * Given an environmental variable name, search
+ * the envp array for its value, returning it
+ * if found or NULL otherwise.
+ */
+static const char *
+get_env(const char *name, const char *envp[])
+{
+    if (envp)
+    {
+        int i;
+        const int namelen = strlen(name);
+        for (i = 0; envp[i]; ++i)
+        {
+            if (!strncmp(envp[i], name, namelen))
+            {
+                const char *cp = envp[i] + namelen;
+                if (*cp == '=')
+                {
+                    return cp + 1;
+                }
+            }
+        }
+    }
+    return NULL;
+}
+
+/*
+ * Return the length of a string array
+ */
+static int
+string_array_len(const char *array[])
+{
+    int i = 0;
+    if (array)
+    {
+        while (array[i])
+        {
+            ++i;
+        }
+    }
+    return i;
+}
+
+/*
+ * Socket read/write functions.
+ */
+
+static int
+recv_control(int fd)
+{
+    unsigned char c;
+    const ssize_t size = read(fd, &c, sizeof(c));
+    if (size == sizeof(c))
+    {
+        return c;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+static int
+send_control(int fd, int code)
+{
+    unsigned char c = (unsigned char) code;
+    const ssize_t size = write(fd, &c, sizeof(c));
+    if (size == sizeof(c))
+    {
+        return (int) size;
+    }
+    else
+    {
+        return -1;
+    }
+}
+
+/*
+ * Daemonize if "daemon" env var is true.
+ * Preserve stderr across daemonization if
+ * "daemon_log_redirect" env var is true.
+ */
+static void
+daemonize(const char *envp[])
+{
+    const char *daemon_string = get_env("daemon", envp);
+    if (daemon_string && daemon_string[0] == '1')
+    {
+        const char *log_redirect = get_env("daemon_log_redirect", envp);
+        int fd = -1;
+        if (log_redirect && log_redirect[0] == '1')
+        {
+            fd = dup(2);
+        }
+        if (daemon(0, 0) < 0)
+        {
+            warn("DOWN-ROOT: daemonization failed");
+        }
+        else if (fd >= 3)
+        {
+            dup2(fd, 2);
+            close(fd);
+        }
+    }
+}
+
+/*
+ * Close most of parent's fds.
+ * Keep stdin/stdout/stderr, plus one
+ * other fd which is presumed to be
+ * our pipe back to parent.
+ * Admittedly, a bit of a kludge,
+ * but posix doesn't give us a kind
+ * of FD_CLOEXEC which will stop
+ * fds from crossing a fork().
+ */
+static void
+close_fds_except(int keep)
+{
+    int i;
+    closelog();
+    for (i = 3; i <= 100; ++i)
+    {
+        if (i != keep)
+        {
+            close(i);
+        }
+    }
+}
+
+/*
+ * Usually we ignore signals, because our parent will
+ * deal with them.
+ */
+static void
+set_signals(void)
+{
+    signal(SIGTERM, SIG_DFL);
+
+    signal(SIGINT, SIG_IGN);
+    signal(SIGHUP, SIG_IGN);
+    signal(SIGUSR1, SIG_IGN);
+    signal(SIGUSR2, SIG_IGN);
+    signal(SIGPIPE, SIG_IGN);
+}
+
+
+static void
+free_context(struct down_root_context *context)
+{
+    if (context)
+    {
+        if (context->command)
+        {
+            free(context->command);
+        }
+        free(context);
+    }
+}
+
+/* Run the script using execve().  As execve() replaces the
+ * current process with the new one, do a fork first before
+ * calling execve()
+ */
+static int
+run_script(char *const *argv, char *const *envp)
+{
+    pid_t pid;
+    int ret = 0;
+
+    pid = fork();
+    if (pid == (pid_t)0)   /* child side */
+    {
+        execve(argv[0], argv, envp);
+        /* If execve() fails to run, exit child with exit code 127 */
+        err(127, "DOWN-ROOT: Failed execute: %s", argv[0]);
+    }
+    else if (pid < (pid_t)0)
+    {
+        warn("DOWN-ROOT: Failed to fork child to run %s", argv[0]);
+        return -1;
+    }
+    else     /* parent side */
+    {
+        if (waitpid(pid, &ret, 0) != pid)
+        {
+            /* waitpid does not return error information via errno */
+            fprintf(stderr, "DOWN-ROOT: waitpid() failed, don't know exit code of child (%s)\n", argv[0]);
+            return -1;
+        }
+    }
+    return ret;
+}
+
+OPENVPN_EXPORT openvpn_plugin_handle_t
+openvpn_plugin_open_v1(unsigned int *type_mask, const char *argv[], const char *envp[])
+{
+    struct down_root_context *context;
+    int i = 0;
+
+    /*
+     * Allocate our context
+     */
+    context = (struct down_root_context *) calloc(1, sizeof(struct down_root_context));
+    if (!context)
+    {
+        warn("DOWN-ROOT: Could not allocate memory for plug-in context");
+        goto error;
+    }
+    context->foreground_fd = -1;
+
+    /*
+     * Intercept the --up and --down callbacks
+     */
+    *type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_UP) | OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_DOWN);
+
+    /*
+     * Make sure we have two string arguments: the first is the .so name,
+     * the second is the script command.
+     */
+    if (string_array_len(argv) < 2)
+    {
+        fprintf(stderr, "DOWN-ROOT: need down script command\n");
+        goto error;
+    }
+
+    /*
+     * Save the arguments in our context
+     */
+    context->command = calloc(string_array_len(argv), sizeof(char *));
+    if (!context->command)
+    {
+        warn("DOWN-ROOT: Could not allocate memory for command array");
+        goto error;
+    }
+
+    /* Ignore argv[0], as it contains just the plug-in file name */
+    for (i = 1; i < string_array_len(argv); i++)
+    {
+        context->command[i-1] = (char *) argv[i];
+    }
+
+    /*
+     * Get verbosity level from environment
+     */
+    {
+        const char *verb_string = get_env("verb", envp);
+        if (verb_string)
+        {
+            context->verb = atoi(verb_string);
+        }
+    }
+
+    return (openvpn_plugin_handle_t) context;
+
+error:
+    free_context(context);
+    return NULL;
+}
+
+OPENVPN_EXPORT int
+openvpn_plugin_func_v1(openvpn_plugin_handle_t handle, const int type, const char *argv[], const char *envp[])
+{
+    struct down_root_context *context = (struct down_root_context *) handle;
+
+    if (type == OPENVPN_PLUGIN_UP && context->foreground_fd == -1) /* fork off a process to hold onto root */
+    {
+        pid_t pid;
+        int fd[2];
+
+        /*
+         * Make a socket for foreground and background processes
+         * to communicate.
+         */
+        if (socketpair(PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
+        {
+            warn("DOWN-ROOT: socketpair call failed");
+            return OPENVPN_PLUGIN_FUNC_ERROR;
+        }
+
+        /*
+         * Fork off the privileged process.  It will remain privileged
+         * even after the foreground process drops its privileges.
+         */
+        pid = fork();
+
+        if (pid)
+        {
+            int status;
+
+            /*
+             * Foreground Process
+             */
+
+            context->background_pid = pid;
+
+            /* close our copy of child's socket */
+            close(fd[1]);
+
+            /* don't let future subprocesses inherit child socket */
+            if (fcntl(fd[0], F_SETFD, FD_CLOEXEC) < 0)
+            {
+                warn("DOWN-ROOT: Set FD_CLOEXEC flag on socket file descriptor failed");
+            }
+
+            /* wait for background child process to initialize */
+            status = recv_control(fd[0]);
+            if (status == RESPONSE_INIT_SUCCEEDED)
+            {
+                context->foreground_fd = fd[0];
+                return OPENVPN_PLUGIN_FUNC_SUCCESS;
+            }
+        }
+        else
+        {
+            /*
+             * Background Process
+             */
+
+            /* close all parent fds except our socket back to parent */
+            close_fds_except(fd[1]);
+
+            /* Ignore most signals (the parent will receive them) */
+            set_signals();
+
+            /* Daemonize if --daemon option is set. */
+            daemonize(envp);
+
+            /* execute the event loop */
+            down_root_server(fd[1], context->command, (char *const *) envp, context->verb);
+
+            close(fd[1]);
+            exit(0);
+            return 0; /* NOTREACHED */
+        }
+    }
+    else if (type == OPENVPN_PLUGIN_DOWN && context->foreground_fd >= 0)
+    {
+        if (send_control(context->foreground_fd, COMMAND_RUN_SCRIPT) == -1)
+        {
+            warn("DOWN-ROOT: Error sending script execution signal to background process");
+        }
+        else
+        {
+            const int status = recv_control(context->foreground_fd);
+            if (status == RESPONSE_SCRIPT_SUCCEEDED)
+            {
+                return OPENVPN_PLUGIN_FUNC_SUCCESS;
+            }
+            if (status == -1)
+            {
+                warn("DOWN-ROOT: Error receiving script execution confirmation from background process");
+            }
+        }
+    }
+    return OPENVPN_PLUGIN_FUNC_ERROR;
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_close_v1(openvpn_plugin_handle_t handle)
+{
+    struct down_root_context *context = (struct down_root_context *) handle;
+
+    if (DEBUG(context->verb))
+    {
+        fprintf(stderr, "DOWN-ROOT: close\n");
+    }
+
+    if (context->foreground_fd >= 0)
+    {
+        /* tell background process to exit */
+        if (send_control(context->foreground_fd, COMMAND_EXIT) == -1)
+        {
+            warn("DOWN-ROOT: Error signalling background process to exit");
+        }
+
+        /* wait for background process to exit */
+        if (context->background_pid > 0)
+        {
+            waitpid(context->background_pid, NULL, 0);
+        }
+
+        close(context->foreground_fd);
+        context->foreground_fd = -1;
+    }
+
+    free_context(context);
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_abort_v1(openvpn_plugin_handle_t handle)
+{
+    struct down_root_context *context = (struct down_root_context *) handle;
+
+    if (context && context->foreground_fd >= 0)
+    {
+        /* tell background process to exit */
+        send_control(context->foreground_fd, COMMAND_EXIT);
+        close(context->foreground_fd);
+        context->foreground_fd = -1;
+    }
+}
+
+/*
+ * Background process -- runs with privilege.
+ */
+static void
+down_root_server(const int fd, char *const *argv, char *const *envp, const int verb)
+{
+    /*
+     * Do initialization
+     */
+    if (DEBUG(verb))
+    {
+        fprintf(stderr, "DOWN-ROOT: BACKGROUND: INIT command='%s'\n", argv[0]);
+    }
+
+    /*
+     * Tell foreground that we initialized successfully
+     */
+    if (send_control(fd, RESPONSE_INIT_SUCCEEDED) == -1)
+    {
+        warn("DOWN-ROOT: BACKGROUND: write error on response socket [1]");
+        goto done;
+    }
+
+    /*
+     * Event loop
+     */
+    while (1)
+    {
+        int command_code;
+        int exit_code = -1;
+
+        /* get a command from foreground process */
+        command_code = recv_control(fd);
+
+        if (DEBUG(verb))
+        {
+            fprintf(stderr, "DOWN-ROOT: BACKGROUND: received command code: %d\n", command_code);
+        }
+
+        switch (command_code)
+        {
+            case COMMAND_RUN_SCRIPT:
+                if ( (exit_code = run_script(argv, envp)) == 0) /* Succeeded */
+                {
+                    if (send_control(fd, RESPONSE_SCRIPT_SUCCEEDED) == -1)
+                    {
+                        warn("DOWN-ROOT: BACKGROUND: write error on response socket [2]");
+                        goto done;
+                    }
+                }
+                else /* Failed */
+                {
+                    fprintf(stderr, "DOWN-ROOT: BACKGROUND: %s exited with exit code %i\n", argv[0], exit_code);
+                    if (send_control(fd, RESPONSE_SCRIPT_FAILED) == -1)
+                    {
+                        warn("DOWN-ROOT: BACKGROUND: write error on response socket [3]");
+                        goto done;
+                    }
+                }
+                break;
+
+            case COMMAND_EXIT:
+                goto done;
+
+            case -1:
+                warn("DOWN-ROOT: BACKGROUND: read error on command channel");
+                goto done;
+
+            default:
+                fprintf(stderr, "DOWN-ROOT: BACKGROUND: unknown command code: code=%d, exiting\n",
+                        command_code);
+                goto done;
+        }
+    }
+
+done:
+    if (DEBUG(verb))
+    {
+        fprintf(stderr, "DOWN-ROOT: BACKGROUND: EXIT\n");
+    }
+
+    return;
+}
+
+
+/*
+ * Local variables:
+ * c-file-style: "bsd"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/src/plugins/down-root/down-root.exports b/src/plugins/down-root/down-root.exports
new file mode 100644
index 0000000..b07937c
--- /dev/null
+++ b/src/plugins/down-root/down-root.exports
@@ -0,0 +1,4 @@
+openvpn_plugin_open_v1
+openvpn_plugin_func_v1
+openvpn_plugin_close_v1
+openvpn_plugin_abort_v1
diff --git a/version.m4 b/version.m4
new file mode 100644
index 0000000..2e23539
--- /dev/null
+++ b/version.m4
@@ -0,0 +1,15 @@
+dnl define the OpenVPN version
+define([PRODUCT_NAME], [OpenVPN])
+define([PRODUCT_TARNAME], [openvpn])
+define([PRODUCT_VERSION_MAJOR], [2])
+define([PRODUCT_VERSION_MINOR], [4])
+define([PRODUCT_VERSION_PATCH], [.9])
+m4_append([PRODUCT_VERSION], [PRODUCT_VERSION_MAJOR])
+m4_append([PRODUCT_VERSION], [PRODUCT_VERSION_MINOR], [[.]])
+m4_append([PRODUCT_VERSION], [PRODUCT_VERSION_PATCH], [[]])
+define([PRODUCT_BUGREPORT], [openvpn-users@lists.sourceforge.net])
+define([PRODUCT_VERSION_RESOURCE], [2,4,9,0])
+dnl define the TAP version
+define([PRODUCT_TAP_WIN_COMPONENT_ID], [tap0901])
+define([PRODUCT_TAP_WIN_MIN_MAJOR], [9])
+define([PRODUCT_TAP_WIN_MIN_MINOR], [9])
diff --git a/version.sh.in b/version.sh.in
new file mode 100644
index 0000000..2af5a36
--- /dev/null
+++ b/version.sh.in
@@ -0,0 +1,4 @@
+OPENVPN_PACKAGE_NAME="@PACKAGE_NAME@"
+OPENVPN_PACKAGE_TARNAME="@PACKAGE_TARNAME@"
+OPENVPN_PACKAGE_VERSION="@PACKAGE_VERSION@"
+OPENVPN_PACKAGE_HOST="@host@"