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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 *
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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100015
16#include "includes.h"
Damien Miller34132e52000-01-14 15:45:46 +110017RCSID("$Id: canohost.c,v 1.7 2000/01/14 04:45:48 damien Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100018
19#include "packet.h"
20#include "xmalloc.h"
21#include "ssh.h"
22
Damien Miller5428f641999-11-25 11:54:57 +110023/*
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 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100027
Damien Miller95def091999-11-25 00:26:21 +110028char *
29get_remote_hostname(int socket)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100030{
Damien Miller34132e52000-01-14 15:45:46 +110031 struct sockaddr_storage from;
32 int i;
33 socklen_t fromlen;
34 struct addrinfo hints, *ai, *aitop;
Damien Miller95def091999-11-25 00:26:21 +110035 char name[MAXHOSTNAMELEN];
Damien Miller34132e52000-01-14 15:45:46 +110036 char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100037
Damien Miller95def091999-11-25 00:26:21 +110038 /* 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();
Damien Millerd4a8b7e1999-10-27 13:42:43 +100044 }
Damien Miller34132e52000-01-14 15:45:46 +110045 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
46 NULL, 0, NI_NUMERICHOST) != 0)
47 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
Damien Miller95def091999-11-25 00:26:21 +110048
Damien Miller34132e52000-01-14 15:45:46 +110049 /* Map the IP address to a host name. */
50 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
51 NULL, 0, NI_NAMEREQD) == 0) {
52 /* Got host name. */
53 name[sizeof(name) - 1] = '\0';
Damien Miller5428f641999-11-25 11:54:57 +110054 /*
55 * Convert it to all lowercase (which is expected by the rest
56 * of this software).
57 */
Damien Miller95def091999-11-25 00:26:21 +110058 for (i = 0; name[i]; i++)
59 if (isupper(name[i]))
60 name[i] = tolower(name[i]);
61
Damien Miller5428f641999-11-25 11:54:57 +110062 /*
63 * Map it back to an IP address and check that the given
64 * address actually is an address of this host. This is
65 * necessary because anyone with access to a name server can
66 * define arbitrary names for an IP address. Mapping from
67 * name to IP address can be trusted better (but can still be
68 * fooled if the intruder has access to the name server of
69 * the domain).
70 */
Damien Miller34132e52000-01-14 15:45:46 +110071 memset(&hints, 0, sizeof(hints));
72 hints.ai_family = from.ss_family;
73 hints.ai_socktype = SOCK_STREAM;
74 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
75 log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
76 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +110077 goto check_ip_options;
78 }
79 /* Look for the address from the list of addresses. */
Damien Miller34132e52000-01-14 15:45:46 +110080 for (ai = aitop; ai; ai = ai->ai_next) {
81 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
82 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
83 (strcmp(ntop, ntop2) == 0))
84 break;
85 }
86 freeaddrinfo(aitop);
87 /* If we reached the end of the list, the address was not there. */
88 if (!ai) {
Damien Miller95def091999-11-25 00:26:21 +110089 /* Address not found for the host name. */
90 log("Address %.100s maps to %.600s, but this does not map back to the address - POSSIBLE BREAKIN ATTEMPT!",
Damien Miller34132e52000-01-14 15:45:46 +110091 ntop, name);
92 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +110093 goto check_ip_options;
94 }
95 /* Address was found for the host name. We accept the host name. */
96 } else {
97 /* Host name not found. Use ascii representation of the address. */
Damien Miller34132e52000-01-14 15:45:46 +110098 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +110099 log("Could not reverse map address %.100s.", name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000100 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000101
Damien Miller95def091999-11-25 00:26:21 +1100102check_ip_options:
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000103
Damien Miller5428f641999-11-25 11:54:57 +1100104 /*
105 * If IP options are supported, make sure there are none (log and
106 * disconnect them if any are found). Basically we are worried about
107 * source routing; it can be used to pretend you are somebody
108 * (ip-address) you are not. That itself may be "almost acceptable"
109 * under certain circumstances, but rhosts autentication is useless
110 * if source routing is accepted. Notice also that if we just dropped
111 * source routing here, the other side could use IP spoofing to do
112 * rest of the interaction and could still bypass security. So we
113 * exit here if we detect any IP options.
114 */
Damien Miller34132e52000-01-14 15:45:46 +1100115 /* IP options -- IPv4 only */
116 if (from.ss_family == AF_INET) {
Damien Miller95def091999-11-25 00:26:21 +1100117 unsigned char options[200], *ucp;
118 char text[1024], *cp;
Damien Miller34132e52000-01-14 15:45:46 +1100119 socklen_t option_size;
120 int ipproto;
Damien Miller95def091999-11-25 00:26:21 +1100121 struct protoent *ip;
122
123 if ((ip = getprotobyname("ip")) != NULL)
124 ipproto = ip->p_proto;
125 else
126 ipproto = IPPROTO_IP;
127 option_size = sizeof(options);
128 if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
Damien Miller34132e52000-01-14 15:45:46 +1100129 &option_size) >= 0 && option_size != 0) {
Damien Miller95def091999-11-25 00:26:21 +1100130 cp = text;
131 /* Note: "text" buffer must be at least 3x as big as options. */
132 for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
133 sprintf(cp, " %2.2x", *ucp);
134 log("Connection from %.100s with IP options:%.800s",
Damien Miller34132e52000-01-14 15:45:46 +1100135 ntop, text);
Damien Miller95def091999-11-25 00:26:21 +1100136 packet_disconnect("Connection from %.100s with IP options:%.800s",
Damien Miller34132e52000-01-14 15:45:46 +1100137 ntop, text);
Damien Miller95def091999-11-25 00:26:21 +1100138 }
139 }
140
141 return xstrdup(name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000142}
143
Damien Miller5428f641999-11-25 11:54:57 +1100144/*
145 * Return the canonical name of the host in the other side of the current
146 * connection. The host name is cached, so it is efficient to call this
147 * several times.
148 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000149
Damien Miller95def091999-11-25 00:26:21 +1100150const char *
151get_canonical_hostname()
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000152{
Damien Miller34132e52000-01-14 15:45:46 +1100153 static char *canonical_host_name = NULL;
154
Damien Miller95def091999-11-25 00:26:21 +1100155 /* Check if we have previously retrieved this same name. */
156 if (canonical_host_name != NULL)
157 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000158
Damien Miller95def091999-11-25 00:26:21 +1100159 /* Get the real hostname if socket; otherwise return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100160 if (packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100161 canonical_host_name = get_remote_hostname(packet_get_connection_in());
162 else
163 canonical_host_name = xstrdup("UNKNOWN");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000164
Damien Miller95def091999-11-25 00:26:21 +1100165 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000166}
167
Damien Miller5428f641999-11-25 11:54:57 +1100168/*
169 * Returns the IP-address of the remote host as a string. The returned
Damien Miller34132e52000-01-14 15:45:46 +1100170 * string must not be freed.
Damien Miller5428f641999-11-25 11:54:57 +1100171 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000172
Damien Miller95def091999-11-25 00:26:21 +1100173const char *
174get_remote_ipaddr()
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000175{
Damien Miller34132e52000-01-14 15:45:46 +1100176 static char *canonical_host_ip = NULL;
177 struct sockaddr_storage from;
178 socklen_t fromlen;
179 int socket;
180 char ntop[NI_MAXHOST];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000181
Damien Miller5428f641999-11-25 11:54:57 +1100182 /* Check whether we have chached the name. */
Damien Miller95def091999-11-25 00:26:21 +1100183 if (canonical_host_ip != NULL)
184 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000185
Damien Miller95def091999-11-25 00:26:21 +1100186 /* If not a socket, return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100187 if (!packet_connection_is_on_socket()) {
Damien Miller95def091999-11-25 00:26:21 +1100188 canonical_host_ip = xstrdup("UNKNOWN");
189 return canonical_host_ip;
190 }
191 /* Get client socket. */
192 socket = packet_get_connection_in();
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000193
Damien Miller95def091999-11-25 00:26:21 +1100194 /* Get IP address of client. */
195 fromlen = sizeof(from);
196 memset(&from, 0, sizeof(from));
197 if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
198 debug("getpeername failed: %.100s", strerror(errno));
199 fatal_cleanup();
200 }
201 /* Get the IP address in ascii. */
Damien Miller34132e52000-01-14 15:45:46 +1100202 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
203 NULL, 0, NI_NUMERICHOST) != 0)
204 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
205
206 canonical_host_ip = xstrdup(ntop);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000207
Damien Miller95def091999-11-25 00:26:21 +1100208 /* Return ip address string. */
209 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000210}
211
Damien Miller34132e52000-01-14 15:45:46 +1100212/* Returns the local/remote port for the socket. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000213
Damien Miller34132e52000-01-14 15:45:46 +1100214int
215get_sock_port(int sock, int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000216{
Damien Miller34132e52000-01-14 15:45:46 +1100217 struct sockaddr_storage from;
218 socklen_t fromlen;
219 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000220
Damien Miller95def091999-11-25 00:26:21 +1100221 /* Get IP address of client. */
222 fromlen = sizeof(from);
223 memset(&from, 0, sizeof(from));
Damien Miller34132e52000-01-14 15:45:46 +1100224 if (local) {
225 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
226 error("getsockname failed: %.100s", strerror(errno));
227 return 0;
228 }
229 } else {
230 if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
231 debug("getpeername failed: %.100s", strerror(errno));
232 fatal_cleanup();
233 }
Damien Miller95def091999-11-25 00:26:21 +1100234 }
235 /* Return port number. */
Damien Miller34132e52000-01-14 15:45:46 +1100236 if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
237 strport, sizeof(strport), NI_NUMERICSERV) != 0)
238 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
239 return atoi(strport);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000240}
241
Damien Miller34132e52000-01-14 15:45:46 +1100242/* Returns remote/local port number for the current connection. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000243
Damien Miller95def091999-11-25 00:26:21 +1100244int
Damien Miller34132e52000-01-14 15:45:46 +1100245get_port(int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000246{
Damien Miller5428f641999-11-25 11:54:57 +1100247 /*
248 * If the connection is not a socket, return 65535. This is
249 * intentionally chosen to be an unprivileged port number.
250 */
Damien Miller34132e52000-01-14 15:45:46 +1100251 if (!packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100252 return 65535;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000253
Damien Miller34132e52000-01-14 15:45:46 +1100254 /* Get socket and return the port number. */
255 return get_sock_port(packet_get_connection_in(), local);
256}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000257
Damien Miller34132e52000-01-14 15:45:46 +1100258int
259get_peer_port(int sock)
260{
261 return get_sock_port(sock, 0);
262}
263
264int
265get_remote_port()
266{
267 return get_port(0);
268}
269
270int
271get_local_port()
272{
273 return get_port(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000274}