/*****************************************************************************\
 *  $Id$
 *****************************************************************************
 *  Copyright (C) 2001-2002 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Chris Dunlap <cdunlap@llnl.gov>.
 *  UCRL-CODE-2002-009.
 *
 *  This file is part of ConMan, a remote console management program.
 *  For details, see <http://www.llnl.gov/linux/conman/>.
 *
 *  ConMan 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.
 *
 *  In addition, as a special exception, the copyright holders give permission
 *  to link the code of portions of this program with the OpenSSL library under
 *  certain conditions as described in each individual source file, 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 file(s) with this exception, you may extend this
 *  exception to your version of the file(s), but you are not obligated to do
 *  so. If you do not wish to do so, delete this exception statement from your
 *  version.  If you delete this exception statement from all source files in
 *  the program, then also delete it here.
 *
 *  ConMan 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 ConMan; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA.
 *****************************************************************************
 *  Refer to "util-net.h" for documentation on public functions.
\*****************************************************************************/


#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif /* HAVE_CONFIG_H */

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <netdb.h>
#include <netinet/in.h>
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>

#include "src/common/strlcpy.h"
#include "src/common/util-net.h"
#include "src/common/macros.h"


#ifndef INET_ADDRSTRLEN
#  define INET_ADDRSTRLEN 16
#endif /* !INET_ADDRSTRLEN */


static pthread_mutex_t hostentLock = PTHREAD_MUTEX_INITIALIZER;


static int copy_hostent(const struct hostent *src, char *dst, int len);
#ifndef NDEBUG
static int validate_hostent_copy(
	const struct hostent *src, const struct hostent *dst);
#endif /* !NDEBUG */


struct hostent * get_host_by_name(const char *name,
				  void *buf, int buflen, int *h_err)
{
/*  gethostbyname() is not thread-safe, and there is no frelling standard
 *    for gethostbyname_r() -- the arg list varies from system to system!
 */
	struct hostent *hptr;
	int n = 0;

	assert(name != NULL);
	assert(buf != NULL);

	slurm_mutex_lock(&hostentLock);
	if ((hptr = gethostbyname(name)))
		n = copy_hostent(hptr, buf, buflen);
	if (h_err)
		*h_err = h_errno;
	slurm_mutex_unlock(&hostentLock);

	if (n < 0) {
		errno = ERANGE;
		return(NULL);
	}
	return(hptr ? (struct hostent *) buf : NULL);
}


struct hostent * get_host_by_addr(const char *addr, int len, int type,
				  void *buf, int buflen, int *h_err)
{
/*  gethostbyaddr() is not thread-safe, and there is no frelling standard
 *    for gethostbyaddr_r() -- the arg list varies from system to system!
 */
	struct hostent *hptr;
	int n = 0;

	assert(addr != NULL);
	assert(buf != NULL);

	slurm_mutex_lock(&hostentLock);
	if ((hptr = gethostbyaddr(addr, len, type)))
		n = copy_hostent(hptr, buf, buflen);
	if (h_err)
		*h_err = h_errno;
	slurm_mutex_unlock(&hostentLock);

	if (n < 0) {
		errno = ERANGE;
		return(NULL);
	}
	return(hptr ? (struct hostent *) buf : NULL);
}


const char * host_strerror(int h_err)
{
	if (h_err == HOST_NOT_FOUND)
		return("Unknown host");
	else if (h_err == TRY_AGAIN)
		return("Transient host name lookup failure");
	else if (h_err == NO_RECOVERY)
		return("Unknown server error");
	else if ((h_err == NO_ADDRESS) || (h_err == NO_DATA))
		return("No address associated with name");
	return("Unknown error");
}


int host_name_to_addr4(const char *name, struct in_addr *addr)
{
	struct hostent *hptr;
	unsigned char buf[HOSTENT_SIZE];

	assert(name != NULL);
	assert(addr != NULL);

	if (!(hptr = get_host_by_name(name, buf, sizeof(buf), NULL)))
		return(-1);
	if (hptr->h_length > 4) {
		errno = ERANGE;
		return(-1);
	}
	memcpy(addr, hptr->h_addr_list[0], hptr->h_length);
	return(0);
}


char * host_addr4_to_name(const struct in_addr *addr, char *dst, int dstlen)
{
	struct hostent *hptr;
	unsigned char buf[HOSTENT_SIZE];

	assert(addr != NULL);
	assert(dst != NULL);

	if (!(hptr = get_host_by_addr((char *) addr, 4, AF_INET,
				      buf, sizeof(buf), NULL)))
		return(NULL);
	if (strlen(hptr->h_name) >= dstlen) {
		errno = ERANGE;
		return(NULL);
	}
	strcpy(dst, hptr->h_name);
	return(dst);
}


char * host_name_to_cname(const char *src, char *dst, int dstlen)
{
	struct hostent *hptr;
	unsigned char buf[HOSTENT_SIZE];
	struct in_addr addr;

	assert(src != NULL);
	assert(dst != NULL);

	if (!(hptr = get_host_by_name(src, buf, sizeof(buf), NULL)))
		return(NULL);
	/*
	 *  If 'src' is an ip-addr string, it will simply be copied to h_name.
	 *    So, we need to perform a reverse query based on the in_addr
	 *    in order to obtain the canonical name of the host.
	 *  Besides, this additional query helps protect against DNS spoofing.
	 */
	memcpy(&addr, hptr->h_addr_list[0], hptr->h_length);
	if (!(hptr = get_host_by_addr((char *) &addr, 4, AF_INET,
				      buf, sizeof(buf), NULL)))
		return(NULL);
	if (strlen(hptr->h_name) >= dstlen) {
		errno = ERANGE;
		return(NULL);
	}
	strcpy(dst, hptr->h_name);
	return(dst);
}


static int copy_hostent(const struct hostent *src, char *buf, int len)
{
/*  Copies the (src) hostent struct (and all of its associated data)
 *    into the buffer (buf) of length (len).
 *  Returns 0 if the copy is successful, or -1 if the length of the buffer
 *    is not large enough to hold the result.
 *
 *  Note that the order in which data is copied into (buf) is done
 *    in such a way as to ensure everything is properly word-aligned.
 *    There is a method to the madness.
 */
	struct hostent *dst;
	int n;
	char **p, **q;

	assert(src != NULL);
	assert(buf != NULL);

	dst = (struct hostent *) buf;
	if ((len -= sizeof(struct hostent)) < 0)
		return(-1);
	dst->h_addrtype = src->h_addrtype;
	dst->h_length = src->h_length;
	buf += sizeof(struct hostent);

	/*  Reserve space for h_aliases[].
	 */
	dst->h_aliases = (char **) buf;
	for (p=src->h_aliases, q=dst->h_aliases, n=0; *p; p++, q++, n++) {;}
	if ((len -= ++n * sizeof(char *)) < 0)
		return(-1);
	buf = (char *) (q + 1);

	/*  Reserve space for h_addr_list[].
	 */
	dst->h_addr_list = (char **) buf;
	for (p=src->h_addr_list, q=dst->h_addr_list, n=0; *p; p++, q++, n++) {;}
	if ((len -= ++n * sizeof(char *)) < 0)
		return(-1);
	buf = (char *) (q + 1);

	/*  Copy h_addr_list[] in_addr structs.
	 */
	for (p=src->h_addr_list, q=dst->h_addr_list; *p; p++, q++) {
		if ((len -= src->h_length) < 0)
			return(-1);
		memcpy(buf, *p, src->h_length);
		*q = buf;
		buf += src->h_length;
	}
	*q = NULL;

	/*  Copy h_aliases[] strings.
	 */
	for (p=src->h_aliases, q=dst->h_aliases; *p; p++, q++) {
		n = strlcpy(buf, *p, len);
		*q = buf;
		buf += ++n;                     /* allow for trailing NUL char */
		if ((len -= n) < 0)
			return(-1);
	}
	*q = NULL;

	/*  Copy h_name string.
	 */
	dst->h_name = buf;
	n = strlcpy(buf, src->h_name, len);
	buf += ++n;                         /* allow for trailing NUL char */
	if ((len -= n) < 0)
		return(-1);

	assert(validate_hostent_copy(src, dst) >= 0);
	return(0);
}


#ifndef NDEBUG
static int validate_hostent_copy(
	const struct hostent *src, const struct hostent *dst)
{
/*  Validates the src hostent struct has been successfully copied into dst.
 *  Returns 0 if the copy is good; o/w, returns -1.
 */
	char **p, **q;

	assert(src != NULL);
	assert(dst != NULL);

	if (!dst->h_name)
		return(-1);
	if (src->h_name == dst->h_name)
		return(-1);
	if (strcmp(src->h_name, dst->h_name))
		return(-1);
	if (src->h_addrtype != dst->h_addrtype)
		return(-1);
	if (src->h_length != dst->h_length)
		return(-1);
	for (p=src->h_aliases, q=dst->h_aliases; *p; p++, q++)
		if ((!q) || (p == q) || (strcmp(*p, *q)))
			return(-1);
	for (p=src->h_addr_list, q=dst->h_addr_list; *p; p++, q++)
		if ((!q) || (p == q) || (memcmp(*p, *q, src->h_length)))
			return(-1);
	return(0);
}
#endif /* !NDEBUG */


#ifndef HAVE_INET_PTON
int inet_pton(int family, const char *str, void *addr)
{
/*  cf. Stevens UNPv1 p72.
 */
	struct in_addr tmpaddr;

	if (family != AF_INET) {
		errno = EAFNOSUPPORT;
		return(-1);
	}
#ifdef HAVE_INET_ATON
	if (!inet_aton(str, &tmpaddr))
		return(0);
#else /* !HAVE_INET_ATON */
	if ((tmpaddr.s_addr = inet_addr(str)) == -1)
		return(0);
#endif /* !HAVE_INET_ATON */

	memcpy(addr, &tmpaddr, sizeof(struct in_addr));
	return(1);
}
#endif /* !HAVE_INET_PTON */


#ifndef HAVE_INET_NTOP
const char * inet_ntop(int family, const void *addr, char *str, size_t len)
{
/*  cf. Stevens UNPv1 p72.
 */
	const unsigned char *p = (const unsigned char *) addr;
	char tmpstr[INET_ADDRSTRLEN];

	assert(str != NULL);

	if (family != AF_INET) {
		errno = EAFNOSUPPORT;
		return(NULL);
	}
	snprintf(tmpstr, sizeof(tmpstr), "%d.%d.%d.%d", p[0], p[1], p[2], p[3]);
	if (strlen(tmpstr) >= len) {
		errno = ENOSPC;
		return(NULL);
	}
	strcpy(str, tmpstr);
	return(str);
}
#endif /* !HAVE_INET_NTOP */