src/openvpn/session_id.c

/*
 *  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 */