[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;

	ssh_client = getenv("SSH_CLIENT");
	if (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;

	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 */
#ifdef INET6
		int af = AF_INET6;
		struct sockaddr_in6 sin;
#else
		int af = AF_INET;
		struct sockaddr_in sin;
#endif
		socklen_t sin_len = sizeof sin;

		memset(&sin, 0, sin_len);
		sin.sin_family = af;
		inet_pton(af, client_addr(fd), &sin.sin_addr.s_addr);

		if (!lookup_name(fd, (struct sockaddr_storage *)&sin, sin_len, 
				name_buf, sizeof name_buf, port_buf, sizeof port_buf))
			check_name(fd, (struct sockaddr_storage *)&sin, name_buf);
	} else {
		struct sockaddr_storage ss;
		socklen_t ss_len = sizeof ss;

		client_sockaddr(fd, &ss, &ss_len);

		if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf, 
				port_buf, sizeof port_buf))
			check_name(fd, &ss, 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
09021eab DD	54	ssh_client = getenv("SSH_CLIENT");
	55	if (ssh_client != NULL) {
	56	strlcpy(addr_buf, ssh_client, sizeof(addr_buf));
	57	/* truncate SSH_CLIENT to just IP address */
	58	p = strchr(addr_buf, ' ');
	59	if (p)
	60	*p = '\0';
	61	else
	62	strlcpy(addr_buf, "0.0.0.0", sizeof("0.0.0.0"));
	63	} else
	64	client_sockaddr(fd, &ss, &length);
0cd2f407 MP	65
0cd2f407 MP	66	getnameinfo((struct sockaddr *)&ss, length,
09021eab DD	67	addr_buf, sizeof(addr_buf), NULL, 0, NI_NUMERICHOST);
09021eab DD	68
0cd2f407 MP	69	return addr_buf;
	70	}
	71
	72
	73	static int get_sockaddr_family(const struct sockaddr_storage *ss)
	74	{
	75	return ((struct sockaddr *) ss)->sa_family;
	76	}
	77
	78
	79	/**
	80	* Return the DNS name of the client.
	81	*
	82	* The name is statically cached so that repeated lookups are quick,
	83	* so there is a limit of one lookup per customer.
	84	*
	85	* If anything goes wrong, including the name->addr->name check, then
	86	* we just use "UNKNOWN", so you can use that value in hosts allow
	87	* lines.
6c92af20 MP	88	*
	89	* After translation from sockaddr to name we do a forward lookup to
	90	* make sure nobody is spoofing PTR records.
0cd2f407 MP	91	**/
	92	char *client_name(int fd)
	93	{
0cd2f407 MP	94	static char name_buf[100];
	95	static char port_buf[100];
	96	static int initialised;
	97
	98	if (initialised) return name_buf;
	99
	100	strcpy(name_buf, default_name);
	101	initialised = 1;
	102
09021eab DD	103	if (getenv("SSH_CLIENT") != NULL) {
	104	/* Look up name of IP address given in $SSH_CLIENT */
	105	#ifdef INET6
	106	int af = AF_INET6;
	107	struct sockaddr_in6 sin;
	108	#else
	109	int af = AF_INET;
	110	struct sockaddr_in sin;
	111	#endif
	112	socklen_t sin_len = sizeof sin;
	113
	114	memset(&sin, 0, sin_len);
	115	sin.sin_family = af;
	116	inet_pton(af, client_addr(fd), &sin.sin_addr.s_addr);
	117
	118	if (!lookup_name(fd, (struct sockaddr_storage *)&sin, sin_len,
	119	name_buf, sizeof name_buf, port_buf, sizeof port_buf))
	120	check_name(fd, (struct sockaddr_storage *)&sin, name_buf);
	121	} else {
	122	struct sockaddr_storage ss;
	123	socklen_t ss_len = sizeof ss;
	124
	125	client_sockaddr(fd, &ss, &ss_len);
	126
	127	if (!lookup_name(fd, &ss, ss_len, name_buf, sizeof name_buf,
	128	port_buf, sizeof port_buf))
	129	check_name(fd, &ss, name_buf);
	130	}
0cd2f407 MP	131
	132	return name_buf;
	133	}
	134
	135
	136
	137	/**
af32f69e MP	138	* Get the sockaddr for the client.
	139	*
	140	* If it comes in as an ipv4 address mapped into IPv6 format then we
	141	* convert it back to a regular IPv4.
0cd2f407 MP	142	**/
	143	void client_sockaddr(int fd,
	144	struct sockaddr_storage *ss,
	145	socklen_t *ss_len)
	146	{
	147	if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
	148	/* FIXME: Can we really not continue? */
	149	rprintf(FERROR, RSYNC_NAME ": getpeername on fd%d failed: %s\n",
	150	fd, strerror(errno));
	151	exit_cleanup(RERR_SOCKETIO);
	152	}
	153
	154	#ifdef INET6
	155	if (get_sockaddr_family(ss) == AF_INET6 &&
	156	IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
	157	/* OK, so ss is in the IPv6 family, but it is really
	158	* an IPv4 address: something like
	159	* "::ffff:10.130.1.2". If we use it as-is, then the
	160	* reverse lookup might fail or perhaps something else
	161	* bad might happen. So instead we convert it to an
	162	* equivalent address in the IPv4 address family. */
	163	struct sockaddr_in6 sin6;
	164	struct sockaddr_in *sin;
	165
	166	memcpy(&sin6, ss, sizeof(sin6));
	167	sin = (struct sockaddr_in *)ss;
	168	memset(sin, 0, sizeof(*sin));
	169	sin->sin_family = AF_INET;
	170	*ss_len = sizeof(struct sockaddr_in);
	171	#ifdef HAVE_SOCKADDR_LEN
	172	sin->sin_len = *ss_len;
	173	#endif
	174	sin->sin_port = sin6.sin6_port;
	175
	176	/* There is a macro to extract the mapped part
	177	* (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
	178	* to be present in the Linux headers. */
	179	memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12],
	180	sizeof(sin->sin_addr));
	181	}
	182	#endif
	183	}
	184
	185
	186	/**
	187	* Look up a name from @p ss into @p name_buf.
6c92af20 MP	188	*
6c92af20 MP	189	* @param fd file descriptor for client socket.
0cd2f407 MP	190	**/
	191	int lookup_name(int fd, const struct sockaddr_storage *ss,
	192	socklen_t ss_len,
	193	char *name_buf, size_t name_buf_len,
	194	char *port_buf, size_t port_buf_len)
	195	{
	196	int name_err;
	197
	198	/* reverse lookup */
	199	name_err = getnameinfo((struct sockaddr *) ss, ss_len,
	200	name_buf, name_buf_len,
	201	port_buf, port_buf_len,
	202	NI_NAMEREQD \| NI_NUMERICSERV);
	203	if (name_err != 0) {
	204	strcpy(name_buf, default_name);
	205	rprintf(FERROR, RSYNC_NAME ": name lookup failed for %s: %s\n",
	206	client_addr(fd),
	207	gai_strerror(name_err));
	208	return name_err;
	209	}
	210
	211	return 0;
	212	}
	213
	214
	215
974f27e7 MP	216	/**
	217	* Compare an addrinfo from the resolver to a sockinfo.
	218	*
	219	* Like strcmp, returns 0 for identical.
	220	**/
	221	int compare_addrinfo_sockaddr(const struct addrinfo *ai,
	222	const struct sockaddr_storage *ss)
	223	{
	224	int ss_family = get_sockaddr_family(ss);
	225	const char fn[] = "compare_addrinfo_sockaddr";
	226
	227	if (ai->ai_family != ss_family) {
	228	rprintf(FERROR,
	229	"%s: response family %d != %d\n",
	230	fn, ai->ai_family, ss_family);
	231	return 1;
	232	}
	233
39e01d2d MP	234	/* The comparison method depends on the particular AF. */
	235	if (ss_family == AF_INET) {
	236	const struct sockaddr_in sin1, sin2;
	237
	238	sin1 = (const struct sockaddr_in *) ss;
	239	sin2 = (const struct sockaddr_in *) ai->ai_addr;
	240
6780f720 MP	241	return memcmp(&sin1->sin_addr, &sin2->sin_addr,
6780f720 MP	242	sizeof sin1->sin_addr);
39e01d2d	243	}
974f27e7	244	#ifdef INET6
39e01d2d	245	else if (ss_family == AF_INET6) {
6780f720 MP	246	const struct sockaddr_in6 sin1, sin2;
	247
	248	sin1 = (const struct sockaddr_in6 *) ss;
	249	sin2 = (const struct sockaddr_in6 *) ai->ai_addr;
	250
	251	return memcmp(&sin1->sin6_addr, &sin2->sin6_addr,
	252	sizeof sin1->sin6_addr);
39e01d2d MP	253	}
	254	#endif /* INET6 */
	255	else {
	256	/* don't know */
974f27e7 MP	257	return 1;
	258	}
	259	}
	260
	261
af32f69e MP	262	/**
	263	* Do a forward lookup on @p name_buf and make sure it corresponds to
	264	* @p ss -- otherwise we may be being spoofed. If we suspect we are,
	265	* then we don't abort the connection but just emit a warning, and
	266	* change @p name_buf to be "UNKNOWN".
6c92af20 MP	267	*
	268	* We don't do anything with the service when checking the name,
	269	* because it doesn't seem that it could be spoofed in any way, and
	270	* getaddrinfo on random service names seems to cause problems on AIX.
af32f69e	271	**/
0cd2f407 MP	272	int check_name(int fd,
0cd2f407 MP	273	const struct sockaddr_storage *ss,
6c92af20	274	char *name_buf)
0cd2f407 MP	275	{
	276	struct addrinfo hints, res, res0;
	277	int error;
	278	int ss_family = get_sockaddr_family(ss);
	279
	280	memset(&hints, 0, sizeof(hints));
39e01d2d MP	281	hints.ai_family = ss_family;
39e01d2d MP	282	hints.ai_flags = AI_CANONNAME;
0cd2f407	283	hints.ai_socktype = SOCK_STREAM;
6c92af20	284	error = getaddrinfo(name_buf, NULL, &hints, &res0);
0cd2f407 MP	285	if (error) {
0cd2f407 MP	286	rprintf(FERROR,
af32f69e MP	287	RSYNC_NAME ": forward name lookup for %s failed: %s\n",
af32f69e MP	288	name_buf, gai_strerror(error));
0cd2f407 MP	289	strcpy(name_buf, default_name);
	290	return error;
	291	}
	292
	293
974f27e7 MP	294	/* Given all these results, we expect that one of them will be
974f27e7 MP	295	* the same as ss. The comparison is a bit complicated. */
0cd2f407	296	for (res = res0; res; res = res->ai_next) {
974f27e7 MP	297	if (!compare_addrinfo_sockaddr(res, ss))
974f27e7 MP	298	break; /* OK, identical */
0cd2f407 MP	299	}
	300
	301	if (!res0) {
	302	/* We hit the end of the list without finding an
	303	* address that was the same as ss. */
	304	rprintf(FERROR, RSYNC_NAME
	305	": no known address for \"%s\": "
	306	"spoofed address?\n",
	307	name_buf);
	308	strcpy(name_buf, default_name);
974f27e7	309	} else if (res == NULL) {
0cd2f407 MP	310	/* We hit the end of the list without finding an
	311	* address that was the same as ss. */
	312	rprintf(FERROR, RSYNC_NAME
	313	": %s is not a known address for \"%s\": "
	314	"spoofed address?\n",
	315	client_addr(fd),
	316	name_buf);
	317	strcpy(name_buf, default_name);
	318	}
	319
	320	freeaddrinfo(res0);
	321	return 0;
	322	}
	323