[openssh.git] / canohost.c

/*
 * 
 * canohost.c
 * 
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * 
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * 
 * Created: Sun Jul  2 17:52:22 1995 ylo
 * 
 * Functions for returning the canonical host name of the remote site.
 * 
 */

#include "includes.h"
RCSID("$Id$");

#include "packet.h"
#include "xmalloc.h"
#include "ssh.h"

/*
 * Return the canonical name of the host at the other end of the socket. The
 * caller should free the returned string with xfree.
 */

char *
get_remote_hostname(int socket)
{
	struct sockaddr_storage from;
	int i;
	socklen_t fromlen;
	struct addrinfo hints, *ai, *aitop;
	char name[MAXHOSTNAMELEN];
	char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];

	/* Get IP address of client. */
	fromlen = sizeof(from);
	memset(&from, 0, sizeof(from));
	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
		debug("getpeername failed: %.100s", strerror(errno));
		fatal_cleanup();
	}

#ifdef IPV4_IN_IPV6
	if (from.ss_family == AF_INET6) {
		struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from;

		/* Detect IPv4 in IPv6 mapped address and convert it to */
		/* plain (AF_INET) IPv4 address */
		if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
			struct sockaddr_in *from4 = (struct sockaddr_in *)&from;
			struct in_addr addr;
			u_int16_t port;

			memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
			port = from6->sin6_port;

			memset(&from, 0, sizeof(from));
			
			from4->sin_family = AF_INET;
			memcpy(&from4->sin_addr, &addr, sizeof(addr));
			from4->sin_port = port;
		}
	}
#endif

	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	     NULL, 0, NI_NUMERICHOST) != 0)
		fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");

	/* Map the IP address to a host name. */
	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
	     NULL, 0, NI_NAMEREQD) == 0) {
		/* Got host name. */
		name[sizeof(name) - 1] = '\0';
		/*
		 * Convert it to all lowercase (which is expected by the rest
		 * of this software).
		 */
		for (i = 0; name[i]; i++)
			if (isupper(name[i]))
				name[i] = tolower(name[i]);

		/*
		 * Map it back to an IP address and check that the given
		 * address actually is an address of this host.  This is
		 * necessary because anyone with access to a name server can
		 * define arbitrary names for an IP address. Mapping from
		 * name to IP address can be trusted better (but can still be
		 * fooled if the intruder has access to the name server of
		 * the domain).
		 */
		memset(&hints, 0, sizeof(hints));
		hints.ai_family = from.ss_family;
		hints.ai_socktype = SOCK_STREAM;
		if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
			log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
			strlcpy(name, ntop, sizeof name);
			goto check_ip_options;
		}
		/* Look for the address from the list of addresses. */
		for (ai = aitop; ai; ai = ai->ai_next) {
			if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
			    sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
			    (strcmp(ntop, ntop2) == 0))
					break;
		}
		freeaddrinfo(aitop);
		/* If we reached the end of the list, the address was not there. */
		if (!ai) {
			/* Address not found for the host name. */
			log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
			    ntop, name);
			strlcpy(name, ntop, sizeof name);
			goto check_ip_options;
		}
		/* Address was found for the host name.  We accept the host name. */
	} else {
		/* Host name not found.  Use ascii representation of the address. */
		strlcpy(name, ntop, sizeof name);
		log("Could not reverse map address %.100s.", name);
	}

check_ip_options:

	/*
	 * If IP options are supported, make sure there are none (log and
	 * disconnect them if any are found).  Basically we are worried about
	 * source routing; it can be used to pretend you are somebody
	 * (ip-address) you are not. That itself may be "almost acceptable"
	 * under certain circumstances, but rhosts autentication is useless
	 * if source routing is accepted. Notice also that if we just dropped
	 * source routing here, the other side could use IP spoofing to do
	 * rest of the interaction and could still bypass security.  So we
	 * exit here if we detect any IP options.
	 */
	/* IP options -- IPv4 only */
	if (from.ss_family == AF_INET) {
		unsigned char options[200], *ucp;
		char text[1024], *cp;
		socklen_t option_size;
		int ipproto;
		struct protoent *ip;

		if ((ip = getprotobyname("ip")) != NULL)
			ipproto = ip->p_proto;
		else
			ipproto = IPPROTO_IP;
		option_size = sizeof(options);
		if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
		    &option_size) >= 0 && option_size != 0) {
			cp = text;
			/* Note: "text" buffer must be at least 3x as big as options. */
			for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
				sprintf(cp, " %2.2x", *ucp);
			log("Connection from %.100s with IP options:%.800s",
			    ntop, text);
			packet_disconnect("Connection from %.100s with IP options:%.800s",
					  ntop, text);
		}
	}

	return xstrdup(name);
}

/*
 * Return the canonical name of the host in the other side of the current
 * connection.  The host name is cached, so it is efficient to call this
 * several times.
 */

const char *
get_canonical_hostname()
{
	static char *canonical_host_name = NULL;

	/* Check if we have previously retrieved this same name. */
	if (canonical_host_name != NULL)
		return canonical_host_name;

	/* Get the real hostname if socket; otherwise return UNKNOWN. */
	if (packet_connection_is_on_socket())
		canonical_host_name = get_remote_hostname(packet_get_connection_in());
	else
		canonical_host_name = xstrdup("UNKNOWN");

	return canonical_host_name;
}

/*
 * Returns the IP-address of the remote host as a string.  The returned
 * string must not be freed.
 */

const char *
get_remote_ipaddr()
{
	static char *canonical_host_ip = NULL;
	struct sockaddr_storage from;
	socklen_t fromlen;
	int socket;
	char ntop[NI_MAXHOST];

	/* Check whether we have chached the name. */
	if (canonical_host_ip != NULL)
		return canonical_host_ip;

	/* If not a socket, return UNKNOWN. */
	if (!packet_connection_is_on_socket()) {
		canonical_host_ip = xstrdup("UNKNOWN");
		return canonical_host_ip;
	}
	/* Get client socket. */
	socket = packet_get_connection_in();

	/* Get IP address of client. */
	fromlen = sizeof(from);
	memset(&from, 0, sizeof(from));
	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
		debug("getpeername failed: %.100s", strerror(errno));
		fatal_cleanup();
	}
	/* Get the IP address in ascii. */
	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	     NULL, 0, NI_NUMERICHOST) != 0)
		fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");

	canonical_host_ip = xstrdup(ntop);

	/* Return ip address string. */
	return canonical_host_ip;
}

/* Returns the local/remote port for the socket. */

int
get_sock_port(int sock, int local)
{
	struct sockaddr_storage from;
	socklen_t fromlen;
	char strport[NI_MAXSERV];

	/* Get IP address of client. */
	fromlen = sizeof(from);
	memset(&from, 0, sizeof(from));
	if (local) {
		if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
			error("getsockname failed: %.100s", strerror(errno));
			return 0;
		}
	} else {
		if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
			debug("getpeername failed: %.100s", strerror(errno));
			fatal_cleanup();
		}
	}
	/* Return port number. */
	if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
	     strport, sizeof(strport), NI_NUMERICSERV) != 0)
		fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
	return atoi(strport);
}

/* Returns remote/local port number for the current connection. */

int 
get_port(int local)
{
	/*
	 * If the connection is not a socket, return 65535.  This is
	 * intentionally chosen to be an unprivileged port number.
	 */
	if (!packet_connection_is_on_socket())
		return 65535;

	/* Get socket and return the port number. */
	return get_sock_port(packet_get_connection_in(), local);
}

int 
get_peer_port(int sock)
{
	return get_sock_port(sock, 0);
}

int 
get_remote_port()
{
	return get_port(0);
}

int
get_local_port()
{
	return get_port(1);
}
Commit	Line	Data
8efc0c15	1	/*
5260325f	2	*
	3	* canohost.c
	4	*
	5	* Author: Tatu Ylonen <ylo@cs.hut.fi>
	6	*
	7	* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	8	* All rights reserved
	9	*
	10	* Created: Sun Jul 2 17:52:22 1995 ylo
	11	*
	12	* Functions for returning the canonical host name of the remote site.
	13	*
	14	*/
8efc0c15	15
	16	#include "includes.h"
	17	RCSID("$Id$");
	18
	19	#include "packet.h"
	20	#include "xmalloc.h"
	21	#include "ssh.h"
	22
aa3378df	23	/*
	24	* Return the canonical name of the host at the other end of the socket. The
	25	* caller should free the returned string with xfree.
	26	*/
8efc0c15	27
5260325f	28	char *
5260325f	29	get_remote_hostname(int socket)
8efc0c15	30	{
48e671d5	31	struct sockaddr_storage from;
	32	int i;
	33	socklen_t fromlen;
	34	struct addrinfo hints, ai, aitop;
5260325f	35	char name[MAXHOSTNAMELEN];
48e671d5	36	char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
5260325f	37
	38	/* Get IP address of client. */
	39	fromlen = sizeof(from);
	40	memset(&from, 0, sizeof(from));
	41	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
	42	debug("getpeername failed: %.100s", strerror(errno));
	43	fatal_cleanup();
	44	}
80faa19f	45
	46	#ifdef IPV4_IN_IPV6
	47	if (from.ss_family == AF_INET6) {
	48	struct sockaddr_in6 from6 = (struct sockaddr_in6 )&from;
	49
	50	/* Detect IPv4 in IPv6 mapped address and convert it to */
	51	/* plain (AF_INET) IPv4 address */
	52	if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
	53	struct sockaddr_in from4 = (struct sockaddr_in )&from;
	54	struct in_addr addr;
	55	u_int16_t port;
	56
	57	memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
	58	port = from6->sin6_port;
	59
	60	memset(&from, 0, sizeof(from));
	61
	62	from4->sin_family = AF_INET;
	63	memcpy(&from4->sin_addr, &addr, sizeof(addr));
	64	from4->sin_port = port;
	65	}
	66	}
	67	#endif
	68
48e671d5	69	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	70	NULL, 0, NI_NUMERICHOST) != 0)
	71	fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
5260325f	72
48e671d5	73	/* Map the IP address to a host name. */
	74	if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
	75	NULL, 0, NI_NAMEREQD) == 0) {
	76	/* Got host name. */
	77	name[sizeof(name) - 1] = '\0';
aa3378df	78	/*
	79	* Convert it to all lowercase (which is expected by the rest
	80	* of this software).
	81	*/
5260325f	82	for (i = 0; name[i]; i++)
	83	if (isupper(name[i]))
	84	name[i] = tolower(name[i]);
	85
aa3378df	86	/*
	87	* Map it back to an IP address and check that the given
	88	* address actually is an address of this host. This is
	89	* necessary because anyone with access to a name server can
	90	* define arbitrary names for an IP address. Mapping from
	91	* name to IP address can be trusted better (but can still be
	92	* fooled if the intruder has access to the name server of
	93	* the domain).
	94	*/
48e671d5	95	memset(&hints, 0, sizeof(hints));
	96	hints.ai_family = from.ss_family;
	97	hints.ai_socktype = SOCK_STREAM;
	98	if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
	99	log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
	100	strlcpy(name, ntop, sizeof name);
5260325f	101	goto check_ip_options;
	102	}
	103	/* Look for the address from the list of addresses. */
48e671d5	104	for (ai = aitop; ai; ai = ai->ai_next) {
	105	if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
	106	sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
	107	(strcmp(ntop, ntop2) == 0))
	108	break;
	109	}
	110	freeaddrinfo(aitop);
	111	/* If we reached the end of the list, the address was not there. */
	112	if (!ai) {
5260325f	113	/* Address not found for the host name. */
5260325f	114	log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
48e671d5	115	ntop, name);
48e671d5	116	strlcpy(name, ntop, sizeof name);
5260325f	117	goto check_ip_options;
	118	}
	119	/* Address was found for the host name. We accept the host name. */
	120	} else {
	121	/* Host name not found. Use ascii representation of the address. */
48e671d5	122	strlcpy(name, ntop, sizeof name);
5260325f	123	log("Could not reverse map address %.100s.", name);
8efc0c15	124	}
5260325f	125
	126	check_ip_options:
	127
aa3378df	128	/*
	129	* If IP options are supported, make sure there are none (log and
	130	* disconnect them if any are found). Basically we are worried about
	131	* source routing; it can be used to pretend you are somebody
	132	* (ip-address) you are not. That itself may be "almost acceptable"
	133	* under certain circumstances, but rhosts autentication is useless
	134	* if source routing is accepted. Notice also that if we just dropped
	135	* source routing here, the other side could use IP spoofing to do
	136	* rest of the interaction and could still bypass security. So we
	137	* exit here if we detect any IP options.
	138	*/
48e671d5	139	/* IP options -- IPv4 only */
48e671d5	140	if (from.ss_family == AF_INET) {
5260325f	141	unsigned char options[200], *ucp;
5260325f	142	char text[1024], *cp;
48e671d5	143	socklen_t option_size;
48e671d5	144	int ipproto;
5260325f	145	struct protoent *ip;
	146
	147	if ((ip = getprotobyname("ip")) != NULL)
	148	ipproto = ip->p_proto;
	149	else
	150	ipproto = IPPROTO_IP;
	151	option_size = sizeof(options);
	152	if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
48e671d5	153	&option_size) >= 0 && option_size != 0) {
5260325f	154	cp = text;
	155	/* Note: "text" buffer must be at least 3x as big as options. */
	156	for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
	157	sprintf(cp, " %2.2x", *ucp);
	158	log("Connection from %.100s with IP options:%.800s",
48e671d5	159	ntop, text);
5260325f	160	packet_disconnect("Connection from %.100s with IP options:%.800s",
48e671d5	161	ntop, text);
5260325f	162	}
8efc0c15	163	}
5260325f	164
5260325f	165	return xstrdup(name);
8efc0c15	166	}
8efc0c15	167
aa3378df	168	/*
	169	* Return the canonical name of the host in the other side of the current
	170	* connection. The host name is cached, so it is efficient to call this
	171	* several times.
	172	*/
8efc0c15	173
5260325f	174	const char *
5260325f	175	get_canonical_hostname()
8efc0c15	176	{
48e671d5	177	static char *canonical_host_name = NULL;
48e671d5	178
5260325f	179	/* Check if we have previously retrieved this same name. */
	180	if (canonical_host_name != NULL)
	181	return canonical_host_name;
8efc0c15	182
5260325f	183	/* Get the real hostname if socket; otherwise return UNKNOWN. */
48e671d5	184	if (packet_connection_is_on_socket())
5260325f	185	canonical_host_name = get_remote_hostname(packet_get_connection_in());
	186	else
	187	canonical_host_name = xstrdup("UNKNOWN");
8efc0c15	188
5260325f	189	return canonical_host_name;
8efc0c15	190	}
8efc0c15	191
aa3378df	192	/*
aa3378df	193	* Returns the IP-address of the remote host as a string. The returned
48e671d5	194	* string must not be freed.
aa3378df	195	*/
8efc0c15	196
5260325f	197	const char *
5260325f	198	get_remote_ipaddr()
8efc0c15	199	{
48e671d5	200	static char *canonical_host_ip = NULL;
	201	struct sockaddr_storage from;
	202	socklen_t fromlen;
	203	int socket;
	204	char ntop[NI_MAXHOST];
5260325f	205
aa3378df	206	/* Check whether we have chached the name. */
5260325f	207	if (canonical_host_ip != NULL)
	208	return canonical_host_ip;
	209
	210	/* If not a socket, return UNKNOWN. */
48e671d5	211	if (!packet_connection_is_on_socket()) {
5260325f	212	canonical_host_ip = xstrdup("UNKNOWN");
	213	return canonical_host_ip;
	214	}
	215	/* Get client socket. */
	216	socket = packet_get_connection_in();
	217
	218	/* Get IP address of client. */
	219	fromlen = sizeof(from);
	220	memset(&from, 0, sizeof(from));
	221	if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
	222	debug("getpeername failed: %.100s", strerror(errno));
	223	fatal_cleanup();
	224	}
	225	/* Get the IP address in ascii. */
48e671d5	226	if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
	227	NULL, 0, NI_NUMERICHOST) != 0)
	228	fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
	229
	230	canonical_host_ip = xstrdup(ntop);
5260325f	231
	232	/* Return ip address string. */
	233	return canonical_host_ip;
8efc0c15	234	}
8efc0c15	235
48e671d5	236	/* Returns the local/remote port for the socket. */
8efc0c15	237
48e671d5	238	int
48e671d5	239	get_sock_port(int sock, int local)
8efc0c15	240	{
48e671d5	241	struct sockaddr_storage from;
	242	socklen_t fromlen;
	243	char strport[NI_MAXSERV];
5260325f	244
	245	/* Get IP address of client. */
	246	fromlen = sizeof(from);
	247	memset(&from, 0, sizeof(from));
48e671d5	248	if (local) {
	249	if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
	250	error("getsockname failed: %.100s", strerror(errno));
	251	return 0;
	252	}
	253	} else {
	254	if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
	255	debug("getpeername failed: %.100s", strerror(errno));
	256	fatal_cleanup();
	257	}
5260325f	258	}
5260325f	259	/* Return port number. */
48e671d5	260	if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
	261	strport, sizeof(strport), NI_NUMERICSERV) != 0)
	262	fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
	263	return atoi(strport);
8efc0c15	264	}
8efc0c15	265
48e671d5	266	/* Returns remote/local port number for the current connection. */
8efc0c15	267
5260325f	268	int
48e671d5	269	get_port(int local)
8efc0c15	270	{
aa3378df	271	/*
	272	* If the connection is not a socket, return 65535. This is
	273	* intentionally chosen to be an unprivileged port number.
	274	*/
48e671d5	275	if (!packet_connection_is_on_socket())
5260325f	276	return 65535;
8efc0c15	277
48e671d5	278	/* Get socket and return the port number. */
	279	return get_sock_port(packet_get_connection_in(), local);
	280	}
	281
	282	int
	283	get_peer_port(int sock)
	284	{
	285	return get_sock_port(sock, 0);
	286	}
8efc0c15	287
48e671d5	288	int
	289	get_remote_port()
	290	{
	291	return get_port(0);
	292	}
	293
	294	int
	295	get_local_port()
	296	{
	297	return get_port(1);
8efc0c15	298	}