[rsync/rsync.git] / clientname.c

/* -*- c-file-style: "linux" -*-
   
   rsync -- fast file replication program
   
   Copyright (C) 1992-2001 by Andrew Tridgell <tridge@samba.org>
   Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
   
   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., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

/**
 * @file clientname.c
 * 
 * Functions for looking up the remote name or addr of a socket.
 *
 * This file is now converted to use the new-style getaddrinfo()
 * interface, which supports IPv6 but is also supported on recent
 * IPv4-only machines.  On systems that don't have that interface, we
 * emulate it using the KAME implementation.
 **/

#include "rsync.h"

static const char default_name[] = "UNKNOWN";


/**
 * Return the IP addr of the client as a string 
 **/
char *client_addr(int fd)
{
	struct sockaddr_storage ss;
	socklen_t length = sizeof ss;
	char *ssh_client, *p;
	static char addr_buf[100];
	static int initialised;

	if (initialised) return addr_buf;

	initialised = 1;

	if ((ssh_client = getenv("SSH_CLIENT")) != NULL) {
		strlcpy(addr_buf, ssh_client, sizeof(addr_buf));
		/* truncate SSH_CLIENT to just IP address */
		p = strchr(addr_buf, ' ');
		if (p)
			*p = '\0';
		else
			strlcpy(addr_buf, "0.0.0.0", sizeof("0.0.0.0"));
	} else
		client_sockaddr(fd, &ss, &length);

	getnameinfo((struct sockaddr *)&ss, length,
		addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST);

	return addr_buf;
}


static int get_sockaddr_family(const struct sockaddr_storage *ss)
{
	return ((struct sockaddr *) ss)->sa_family;
}


/**
 * Return the DNS name of the client.
 *
 * The name is statically cached so that repeated lookups are quick,
 * so there is a limit of one lookup per customer.
 *
 * If anything goes wrong, including the name->addr->name check, then
 * we just use "UNKNOWN", so you can use that value in hosts allow
 * lines.
 *
 * After translation from sockaddr to name we do a forward lookup to
 * make sure nobody is spoofing PTR records.
 **/
char *client_name(int fd)
{
	static char name_buf[100];
	static char port_buf[100];
	static int initialised;
	struct sockaddr_storage *ssp;
	socklen_t ss_len;

	if (initialised) return name_buf;

	strcpy(name_buf, default_name);
	initialised = 1;

	if (getenv("SSH_CLIENT") != NULL) {
		/* Look up name of IP address given in $SSH_CLIENT */
		char *addr = client_addr(fd);
		struct sockaddr_in sin;
#ifdef INET6
		int dots = 0;
		char *p;
		struct sockaddr_in6 sin6;

		for (p = addr; *p && (dots < 3); p++) {
		    if (*p == '.')
			dots++;
		}
		if (dots > 3) {
			/* more than 4 parts to IP address, must be ipv6 */
			ssp = (struct sockaddr_storage *) &sin6;
			ss_len = sizeof sin6;
			memset(ssp, 0, ss_len);
			inet_pton(AF_INET6, addr, &sin6.sin6_addr.s6_addr);
			sin6.sin6_family = AF_INET6;
		} else
#endif
		{
			ssp = (struct sockaddr_storage *) &sin;
			ss_len = sizeof sin;
			memset(ssp, 0, ss_len);
			inet_pton(AF_INET, addr, &sin.sin_addr.s_addr);
			sin.sin_family = AF_INET;
		}

	} else {
		struct sockaddr_storage ss;

		ss_len = sizeof ss;
		ssp = &ss;

		client_sockaddr(fd, &ss, &ss_len);

	}

	if (!lookup_name(fd, ssp, ss_len, name_buf, sizeof name_buf, 
			port_buf, sizeof port_buf))
		check_name(fd, ssp, name_buf);

	return name_buf;
}


/**
 * Get the sockaddr for the client.
 *
 * If it comes in as an ipv4 address mapped into IPv6 format then we
 * convert it back to a regular IPv4.
 **/
void client_sockaddr(int fd,
		     struct sockaddr_storage *ss,
		     socklen_t *ss_len)
{
	if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
		/* FIXME: Can we really not continue? */
		rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n",
			fd, strerror(errno));
		exit_cleanup(RERR_SOCKETIO);
	}

#ifdef INET6
        if (get_sockaddr_family(ss) == AF_INET6 && 
	    IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
		/* OK, so ss is in the IPv6 family, but it is really
		 * an IPv4 address: something like
		 * "::ffff:10.130.1.2".  If we use it as-is, then the
		 * reverse lookup might fail or perhaps something else
		 * bad might happen.  So instead we convert it to an
		 * equivalent address in the IPv4 address family.  */
		struct sockaddr_in6 sin6;
		struct sockaddr_in *sin;

		memcpy(&sin6, ss, sizeof(sin6));
		sin = (struct sockaddr_in *)ss;
		memset(sin, 0, sizeof(*sin));
		sin->sin_family = AF_INET;
		*ss_len = sizeof(struct sockaddr_in);
#ifdef HAVE_SOCKADDR_LEN
		sin->sin_len = *ss_len;
#endif
		sin->sin_port = sin6.sin6_port;

		/* There is a macro to extract the mapped part
		 * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
		 * to be present in the Linux headers. */
		memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12],
			sizeof(sin->sin_addr));
        }
#endif
}


/**
 * Look up a name from @p ss into @p name_buf.
 *
 * @param fd file descriptor for client socket.
 **/
int lookup_name(int fd, const struct sockaddr_storage *ss,
		socklen_t ss_len,
		char *name_buf, size_t name_buf_len,
		char *port_buf, size_t port_buf_len)
{
	int name_err;
	
	/* reverse lookup */
	name_err = getnameinfo((struct sockaddr *) ss, ss_len,
			       name_buf, name_buf_len,
			       port_buf, port_buf_len,
			       NI_NAMEREQD | NI_NUMERICSERV);
	if (name_err != 0) {
		strcpy(name_buf, default_name);
		rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n",
			client_addr(fd),
			gai_strerror(name_err));
		return name_err;
	}

	return 0;
}


/**
 * Compare an addrinfo from the resolver to a sockinfo.
 *
 * Like strcmp, returns 0 for identical.
 **/
int compare_addrinfo_sockaddr(const struct addrinfo *ai,
			      const struct sockaddr_storage *ss)
{
	int ss_family = get_sockaddr_family(ss);
	const char fn[] = "compare_addrinfo_sockaddr";
		      
	if (ai->ai_family != ss_family) {
		rprintf(FERROR,
			"%s: response family %d != %d\n",
			fn, ai->ai_family, ss_family);
		return 1;
	}

	/* The comparison method depends on the particular AF. */
	if (ss_family == AF_INET) {
		const struct sockaddr_in *sin1, *sin2;

		sin1 = (const struct sockaddr_in *) ss;
		sin2 = (const struct sockaddr_in *) ai->ai_addr;
		
		return memcmp(&sin1->sin_addr, &sin2->sin_addr,
			      sizeof sin1->sin_addr);
	}
#ifdef INET6
	else if (ss_family == AF_INET6) {
		const struct sockaddr_in6 *sin1, *sin2;

		sin1 = (const struct sockaddr_in6 *) ss;
		sin2 = (const struct sockaddr_in6 *) ai->ai_addr;
		
		return memcmp(&sin1->sin6_addr, &sin2->sin6_addr,
			      sizeof sin1->sin6_addr);
	}
#endif /* INET6 */
	else {
		/* don't know */
		return 1;
	}
}


/**
 * Do a forward lookup on @p name_buf and make sure it corresponds to
 * @p ss -- otherwise we may be being spoofed.  If we suspect we are,
 * then we don't abort the connection but just emit a warning, and
 * change @p name_buf to be "UNKNOWN".
 *
 * We don't do anything with the service when checking the name,
 * because it doesn't seem that it could be spoofed in any way, and
 * getaddrinfo on random service names seems to cause problems on AIX.
 **/
int check_name(int fd,
	       const struct sockaddr_storage *ss,
	       char *name_buf)
{
	struct addrinfo hints, *res, *res0;
	int error;
	int ss_family = get_sockaddr_family(ss);

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = ss_family;
	hints.ai_flags = AI_CANONNAME;
	hints.ai_socktype = SOCK_STREAM;
	error = getaddrinfo(name_buf, NULL, &hints, &res0);
	if (error) {
		rprintf(FERROR,
			RSYNC_NAME ": forward name lookup for %s failed: %s\n",
			name_buf, gai_strerror(error));
		strcpy(name_buf, default_name);
		return error;
	}


	/* Given all these results, we expect that one of them will be
	 * the same as ss.  The comparison is a bit complicated. */
	for (res = res0; res; res = res->ai_next) {
		if (!compare_addrinfo_sockaddr(res, ss))
			break;	/* OK, identical */
	}

	if (!res0) {
		/* We hit the end of the list without finding an
		 * address that was the same as ss. */
		rprintf(FERROR, RSYNC_NAME
			": no known address for \"%s\": "
			"spoofed address?\n",
			name_buf);
		strcpy(name_buf, default_name);
	} else if (res == NULL) {
		/* We hit the end of the list without finding an
		 * address that was the same as ss. */
		rprintf(FERROR, RSYNC_NAME
			": %s is not a known address for \"%s\": "
			"spoofed address?\n",
			client_addr(fd),
			name_buf);
		strcpy(name_buf, default_name);
	}

	freeaddrinfo(res0);
	return 0;
}
Commit	Line	Data
0cd2f407 MP	1	/* -- c-file-style: "linux" --
	2
	3	rsync -- fast file replication program
	4
	5	Copyright (C) 1992-2001 by Andrew Tridgell <tridge@samba.org>
	6	Copyright (C) 2001, 2002 by Martin Pool <mbp@samba.org>
	7
	8	This program is free software; you can redistribute it and/or modify
	9	it under the terms of the GNU General Public License as published by
	10	the Free Software Foundation; either version 2 of the License, or
	11	(at your option) any later version.
	12
	13	This program is distributed in the hope that it will be useful,
	14	but WITHOUT ANY WARRANTY; without even the implied warranty of
	15	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	16	GNU General Public License for more details.
	17
	18	You should have received a copy of the GNU General Public License
	19	along with this program; if not, write to the Free Software
	20	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
	21	*/
	22
	23	/**
	24	* @file clientname.c
	25	*
	26	* Functions for looking up the remote name or addr of a socket.
	27	*
	28	* This file is now converted to use the new-style getaddrinfo()
	29	* interface, which supports IPv6 but is also supported on recent
	30	* IPv4-only machines. On systems that don't have that interface, we
	31	* emulate it using the KAME implementation.
	32	**/
	33
	34	#include "rsync.h"
	35
	36	static const char default_name[] = "UNKNOWN";
	37
	38
	39	/**
	40	* Return the IP addr of the client as a string
	41	**/
	42	char *client_addr(int fd)
	43	{
	44	struct sockaddr_storage ss;
	45	socklen_t length = sizeof ss;
09021eab	46	char ssh_client, p;
0cd2f407 MP	47	static char addr_buf[100];
	48	static int initialised;
	49
	50	if (initialised) return addr_buf;
	51
	52	initialised = 1;
	53
a6d8c3f3	54	if ((ssh_client = getenv("SSH_CLIENT")) != NULL) {
09021eab DD	55	strlcpy(addr_buf, ssh_client, sizeof(addr_buf));
	56	/* truncate SSH_CLIENT to just IP address */
	57	p = strchr(addr_buf, ' ');
	58	if (p)
	59	*p = '\0';
	60	else
	61	strlcpy(addr_buf, "0.0.0.0", sizeof("0.0.0.0"));
	62	} else
	63	client_sockaddr(fd, &ss, &length);
0cd2f407 MP	64
0cd2f407 MP	65	getnameinfo((struct sockaddr *)&ss, length,
09021eab DD	66	addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST);
09021eab DD	67
0cd2f407 MP	68	return addr_buf;
	69	}
	70
	71
	72	static int get_sockaddr_family(const struct sockaddr_storage *ss)
	73	{
	74	return ((struct sockaddr *) ss)->sa_family;
	75	}
	76
	77
	78	/**
	79	* Return the DNS name of the client.
	80	*
	81	* The name is statically cached so that repeated lookups are quick,
	82	* so there is a limit of one lookup per customer.
	83	*
	84	* If anything goes wrong, including the name->addr->name check, then
	85	* we just use "UNKNOWN", so you can use that value in hosts allow
	86	* lines.
6c92af20 MP	87	*
	88	* After translation from sockaddr to name we do a forward lookup to
	89	* make sure nobody is spoofing PTR records.
0cd2f407 MP	90	**/
	91	char *client_name(int fd)
	92	{
0cd2f407 MP	93	static char name_buf[100];
	94	static char port_buf[100];
	95	static int initialised;
1e736b8f DD	96	struct sockaddr_storage *ssp;
1e736b8f DD	97	socklen_t ss_len;
0cd2f407 MP	98
	99	if (initialised) return name_buf;
	100
	101	strcpy(name_buf, default_name);
	102	initialised = 1;
	103
09021eab DD	104	if (getenv("SSH_CLIENT") != NULL) {
09021eab DD	105	/* Look up name of IP address given in $SSH_CLIENT */
1e736b8f	106	char *addr = client_addr(fd);
09021eab	107	struct sockaddr_in sin;
a6d8c3f3	108	#ifdef INET6
1e736b8f DD	109	int dots = 0;
	110	char *p;
	111	struct sockaddr_in6 sin6;
	112
	113	for (p = addr; *p && (dots < 3); p++) {
	114	if (*p == '.')
	115	dots++;
	116	}
	117	if (dots > 3) {
	118	/* more than 4 parts to IP address, must be ipv6 */
	119	ssp = (struct sockaddr_storage *) &sin6;
	120	ss_len = sizeof sin6;
	121	memset(ssp, 0, ss_len);
	122	inet_pton(AF_INET6, addr, &sin6.sin6_addr.s6_addr);
	123	sin6.sin6_family = AF_INET6;
	124	} else
a6d8c3f3	125	#endif
1e736b8f DD	126	{
	127	ssp = (struct sockaddr_storage *) &sin;
	128	ss_len = sizeof sin;
	129	memset(ssp, 0, ss_len);
	130	inet_pton(AF_INET, addr, &sin.sin_addr.s_addr);
	131	sin.sin_family = AF_INET;
	132	}
09021eab	133
09021eab DD	134	} else {
09021eab DD	135	struct sockaddr_storage ss;
1e736b8f DD	136
	137	ss_len = sizeof ss;
	138	ssp = &ss;
09021eab DD	139
	140	client_sockaddr(fd, &ss, &ss_len);
	141
09021eab	142	}
0cd2f407	143
1e736b8f DD	144	if (!lookup_name(fd, ssp, ss_len, name_buf, sizeof name_buf,
	145	port_buf, sizeof port_buf))
	146	check_name(fd, ssp, name_buf);
	147
0cd2f407 MP	148	return name_buf;
	149	}
	150
	151
	152
	153	/**
af32f69e MP	154	* Get the sockaddr for the client.
	155	*
	156	* If it comes in as an ipv4 address mapped into IPv6 format then we
	157	* convert it back to a regular IPv4.
0cd2f407 MP	158	**/
	159	void client_sockaddr(int fd,
	160	struct sockaddr_storage *ss,
	161	socklen_t *ss_len)
	162	{
	163	if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
	164	/* FIXME: Can we really not continue? */
	165	rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n",
	166	fd, strerror(errno));
	167	exit_cleanup(RERR_SOCKETIO);
	168	}
	169
	170	#ifdef INET6
	171	if (get_sockaddr_family(ss) == AF_INET6 &&
	172	IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
	173	/* OK, so ss is in the IPv6 family, but it is really
	174	* an IPv4 address: something like
	175	* "::ffff:10.130.1.2". If we use it as-is, then the
	176	* reverse lookup might fail or perhaps something else
	177	* bad might happen. So instead we convert it to an
	178	* equivalent address in the IPv4 address family. */
	179	struct sockaddr_in6 sin6;
	180	struct sockaddr_in *sin;
	181
	182	memcpy(&sin6, ss, sizeof(sin6));
	183	sin = (struct sockaddr_in *)ss;
	184	memset(sin, 0, sizeof(*sin));
	185	sin->sin_family = AF_INET;
	186	*ss_len = sizeof(struct sockaddr_in);
	187	#ifdef HAVE_SOCKADDR_LEN
	188	sin->sin_len = *ss_len;
	189	#endif
	190	sin->sin_port = sin6.sin6_port;
	191
	192	/* There is a macro to extract the mapped part
	193	* (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
	194	* to be present in the Linux headers. */
	195	memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12],
	196	sizeof(sin->sin_addr));
	197	}
	198	#endif
	199	}
	200
	201
	202	/**
	203	* Look up a name from @p ss into @p name_buf.
6c92af20 MP	204	*
6c92af20 MP	205	* @param fd file descriptor for client socket.
0cd2f407 MP	206	**/
	207	int lookup_name(int fd, const struct sockaddr_storage *ss,
	208	socklen_t ss_len,
	209	char *name_buf, size_t name_buf_len,
	210	char *port_buf, size_t port_buf_len)
	211	{
	212	int name_err;
	213
	214	/* reverse lookup */
	215	name_err = getnameinfo((struct sockaddr *) ss, ss_len,
	216	name_buf, name_buf_len,
	217	port_buf, port_buf_len,
	218	NI_NAMEREQD \| NI_NUMERICSERV);
	219	if (name_err != 0) {
	220	strcpy(name_buf, default_name);
	221	rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n",
	222	client_addr(fd),
	223	gai_strerror(name_err));
	224	return name_err;
	225	}
	226
	227	return 0;
	228	}
	229
	230
	231
974f27e7 MP	232	/**
	233	* Compare an addrinfo from the resolver to a sockinfo.
	234	*
	235	* Like strcmp, returns 0 for identical.
	236	**/
	237	int compare_addrinfo_sockaddr(const struct addrinfo *ai,
	238	const struct sockaddr_storage *ss)
	239	{
	240	int ss_family = get_sockaddr_family(ss);
	241	const char fn[] = "compare_addrinfo_sockaddr";
	242
	243	if (ai->ai_family != ss_family) {
	244	rprintf(FERROR,
	245	"%s: response family %d != %d\n",
	246	fn, ai->ai_family, ss_family);
	247	return 1;
	248	}
	249
39e01d2d MP	250	/* The comparison method depends on the particular AF. */
	251	if (ss_family == AF_INET) {
	252	const struct sockaddr_in sin1, sin2;
	253
	254	sin1 = (const struct sockaddr_in *) ss;
	255	sin2 = (const struct sockaddr_in *) ai->ai_addr;
	256
6780f720 MP	257	return memcmp(&sin1->sin_addr, &sin2->sin_addr,
6780f720 MP	258	sizeof sin1->sin_addr);
39e01d2d	259	}
974f27e7	260	#ifdef INET6
39e01d2d	261	else if (ss_family == AF_INET6) {
6780f720 MP	262	const struct sockaddr_in6 sin1, sin2;
	263
	264	sin1 = (const struct sockaddr_in6 *) ss;
	265	sin2 = (const struct sockaddr_in6 *) ai->ai_addr;
	266
	267	return memcmp(&sin1->sin6_addr, &sin2->sin6_addr,
	268	sizeof sin1->sin6_addr);
39e01d2d MP	269	}
	270	#endif /* INET6 */
	271	else {
	272	/* don't know */
974f27e7 MP	273	return 1;
	274	}
	275	}
	276
	277
af32f69e MP	278	/**
	279	* Do a forward lookup on @p name_buf and make sure it corresponds to
	280	* @p ss -- otherwise we may be being spoofed. If we suspect we are,
	281	* then we don't abort the connection but just emit a warning, and
	282	* change @p name_buf to be "UNKNOWN".
6c92af20 MP	283	*
	284	* We don't do anything with the service when checking the name,
	285	* because it doesn't seem that it could be spoofed in any way, and
	286	* getaddrinfo on random service names seems to cause problems on AIX.
af32f69e	287	**/
0cd2f407 MP	288	int check_name(int fd,
0cd2f407 MP	289	const struct sockaddr_storage *ss,
6c92af20	290	char *name_buf)
0cd2f407 MP	291	{
	292	struct addrinfo hints, res, res0;
	293	int error;
	294	int ss_family = get_sockaddr_family(ss);
	295
	296	memset(&hints, 0, sizeof(hints));
39e01d2d MP	297	hints.ai_family = ss_family;
39e01d2d MP	298	hints.ai_flags = AI_CANONNAME;
0cd2f407	299	hints.ai_socktype = SOCK_STREAM;
6c92af20	300	error = getaddrinfo(name_buf, NULL, &hints, &res0);
0cd2f407 MP	301	if (error) {
0cd2f407 MP	302	rprintf(FERROR,
af32f69e MP	303	RSYNC_NAME ": forward name lookup for %s failed: %s\n",
af32f69e MP	304	name_buf, gai_strerror(error));
0cd2f407 MP	305	strcpy(name_buf, default_name);
	306	return error;
	307	}
	308
	309
974f27e7 MP	310	/* Given all these results, we expect that one of them will be
974f27e7 MP	311	* the same as ss. The comparison is a bit complicated. */
0cd2f407	312	for (res = res0; res; res = res->ai_next) {
974f27e7 MP	313	if (!compare_addrinfo_sockaddr(res, ss))
974f27e7 MP	314	break; /* OK, identical */
0cd2f407 MP	315	}
	316
	317	if (!res0) {
	318	/* We hit the end of the list without finding an
	319	* address that was the same as ss. */
	320	rprintf(FERROR, RSYNC_NAME
	321	": no known address for \"%s\": "
	322	"spoofed address?\n",
	323	name_buf);
	324	strcpy(name_buf, default_name);
974f27e7	325	} else if (res == NULL) {
0cd2f407 MP	326	/* We hit the end of the list without finding an
	327	* address that was the same as ss. */
	328	rprintf(FERROR, RSYNC_NAME
	329	": %s is not a known address for \"%s\": "
	330	"spoofed address?\n",
	331	client_addr(fd),
	332	name_buf);
	333	strcpy(name_buf, default_name);
	334	}
	335
	336	freeaddrinfo(res0);
	337	return 0;
	338	}
	339