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Damien Millerd4a8b7e1999-10-27 13:42:43 +10001/*
Damien Miller95def091999-11-25 00:26:21 +11002 * Author: Tatu Ylonen <ylo@cs.hut.fi>
Damien Miller95def091999-11-25 00:26:21 +11003 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
Damien Miller95def091999-11-25 00:26:21 +11005 * Functions for returning the canonical host name of the remote site.
Damien Miller4af51302000-04-16 11:18:38 +10006 *
Damien Millere4340be2000-09-16 13:29:08 +11007 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
Damien Miller95def091999-11-25 00:26:21 +110012 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100013
14#include "includes.h"
Damien Millere4340be2000-09-16 13:29:08 +110015RCSID("$OpenBSD: canohost.c,v 1.15 2000/09/07 21:13:37 markus Exp $");
Damien Millerd4a8b7e1999-10-27 13:42:43 +100016
17#include "packet.h"
18#include "xmalloc.h"
19#include "ssh.h"
20
Damien Miller5428f641999-11-25 11:54:57 +110021/*
22 * Return the canonical name of the host at the other end of the socket. The
23 * caller should free the returned string with xfree.
24 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +100025
Damien Miller95def091999-11-25 00:26:21 +110026char *
27get_remote_hostname(int socket)
Damien Millerd4a8b7e1999-10-27 13:42:43 +100028{
Damien Miller34132e52000-01-14 15:45:46 +110029 struct sockaddr_storage from;
30 int i;
31 socklen_t fromlen;
32 struct addrinfo hints, *ai, *aitop;
Damien Miller95def091999-11-25 00:26:21 +110033 char name[MAXHOSTNAMELEN];
Damien Miller34132e52000-01-14 15:45:46 +110034 char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
Damien Millerd4a8b7e1999-10-27 13:42:43 +100035
Damien Miller95def091999-11-25 00:26:21 +110036 /* Get IP address of client. */
37 fromlen = sizeof(from);
38 memset(&from, 0, sizeof(from));
39 if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
40 debug("getpeername failed: %.100s", strerror(errno));
41 fatal_cleanup();
Damien Millerd4a8b7e1999-10-27 13:42:43 +100042 }
Damien Miller7bcb0892000-03-11 20:45:40 +110043
44#ifdef IPV4_IN_IPV6
45 if (from.ss_family == AF_INET6) {
46 struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from;
47
48 /* Detect IPv4 in IPv6 mapped address and convert it to */
49 /* plain (AF_INET) IPv4 address */
50 if (IN6_IS_ADDR_V4MAPPED(&from6->sin6_addr)) {
51 struct sockaddr_in *from4 = (struct sockaddr_in *)&from;
52 struct in_addr addr;
53 u_int16_t port;
54
55 memcpy(&addr, ((char *)&from6->sin6_addr) + 12, sizeof(addr));
56 port = from6->sin6_port;
57
58 memset(&from, 0, sizeof(from));
59
60 from4->sin_family = AF_INET;
61 memcpy(&from4->sin_addr, &addr, sizeof(addr));
62 from4->sin_port = port;
63 }
64 }
65#endif
66
Damien Miller34132e52000-01-14 15:45:46 +110067 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
68 NULL, 0, NI_NUMERICHOST) != 0)
69 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
Damien Miller95def091999-11-25 00:26:21 +110070
Damien Miller34132e52000-01-14 15:45:46 +110071 /* Map the IP address to a host name. */
72 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
73 NULL, 0, NI_NAMEREQD) == 0) {
74 /* Got host name. */
75 name[sizeof(name) - 1] = '\0';
Damien Miller5428f641999-11-25 11:54:57 +110076 /*
77 * Convert it to all lowercase (which is expected by the rest
78 * of this software).
79 */
Damien Miller95def091999-11-25 00:26:21 +110080 for (i = 0; name[i]; i++)
81 if (isupper(name[i]))
82 name[i] = tolower(name[i]);
83
Damien Miller5428f641999-11-25 11:54:57 +110084 /*
85 * Map it back to an IP address and check that the given
86 * address actually is an address of this host. This is
87 * necessary because anyone with access to a name server can
88 * define arbitrary names for an IP address. Mapping from
89 * name to IP address can be trusted better (but can still be
90 * fooled if the intruder has access to the name server of
91 * the domain).
92 */
Damien Miller34132e52000-01-14 15:45:46 +110093 memset(&hints, 0, sizeof(hints));
94 hints.ai_family = from.ss_family;
95 hints.ai_socktype = SOCK_STREAM;
96 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
97 log("reverse mapping checking getaddrinfo for %.700s failed - POSSIBLE BREAKIN ATTEMPT!", name);
98 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +110099 goto check_ip_options;
100 }
101 /* Look for the address from the list of addresses. */
Damien Miller34132e52000-01-14 15:45:46 +1100102 for (ai = aitop; ai; ai = ai->ai_next) {
103 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
104 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
105 (strcmp(ntop, ntop2) == 0))
106 break;
107 }
108 freeaddrinfo(aitop);
109 /* If we reached the end of the list, the address was not there. */
110 if (!ai) {
Damien Miller95def091999-11-25 00:26:21 +1100111 /* Address not found for the host name. */
112 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 +1100113 ntop, name);
114 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +1100115 goto check_ip_options;
116 }
117 /* Address was found for the host name. We accept the host name. */
118 } else {
119 /* Host name not found. Use ascii representation of the address. */
Damien Miller34132e52000-01-14 15:45:46 +1100120 strlcpy(name, ntop, sizeof name);
Damien Miller95def091999-11-25 00:26:21 +1100121 log("Could not reverse map address %.100s.", name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000122 }
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000123
Damien Miller95def091999-11-25 00:26:21 +1100124check_ip_options:
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000125
Damien Miller5428f641999-11-25 11:54:57 +1100126 /*
127 * If IP options are supported, make sure there are none (log and
128 * disconnect them if any are found). Basically we are worried about
129 * source routing; it can be used to pretend you are somebody
130 * (ip-address) you are not. That itself may be "almost acceptable"
131 * under certain circumstances, but rhosts autentication is useless
132 * if source routing is accepted. Notice also that if we just dropped
133 * source routing here, the other side could use IP spoofing to do
134 * rest of the interaction and could still bypass security. So we
135 * exit here if we detect any IP options.
136 */
Damien Miller34132e52000-01-14 15:45:46 +1100137 /* IP options -- IPv4 only */
138 if (from.ss_family == AF_INET) {
Damien Miller95def091999-11-25 00:26:21 +1100139 unsigned char options[200], *ucp;
140 char text[1024], *cp;
Damien Miller34132e52000-01-14 15:45:46 +1100141 socklen_t option_size;
142 int ipproto;
Damien Miller95def091999-11-25 00:26:21 +1100143 struct protoent *ip;
144
145 if ((ip = getprotobyname("ip")) != NULL)
146 ipproto = ip->p_proto;
147 else
148 ipproto = IPPROTO_IP;
149 option_size = sizeof(options);
150 if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
Damien Miller34132e52000-01-14 15:45:46 +1100151 &option_size) >= 0 && option_size != 0) {
Damien Miller95def091999-11-25 00:26:21 +1100152 cp = text;
153 /* Note: "text" buffer must be at least 3x as big as options. */
154 for (ucp = options; option_size > 0; ucp++, option_size--, cp += 3)
155 sprintf(cp, " %2.2x", *ucp);
156 log("Connection from %.100s with IP options:%.800s",
Damien Miller34132e52000-01-14 15:45:46 +1100157 ntop, text);
Damien Miller95def091999-11-25 00:26:21 +1100158 packet_disconnect("Connection from %.100s with IP options:%.800s",
Damien Miller34132e52000-01-14 15:45:46 +1100159 ntop, text);
Damien Miller95def091999-11-25 00:26:21 +1100160 }
161 }
162
163 return xstrdup(name);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000164}
165
Damien Miller5428f641999-11-25 11:54:57 +1100166/*
167 * Return the canonical name of the host in the other side of the current
168 * connection. The host name is cached, so it is efficient to call this
169 * several times.
170 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000171
Damien Miller95def091999-11-25 00:26:21 +1100172const char *
173get_canonical_hostname()
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000174{
Damien Miller34132e52000-01-14 15:45:46 +1100175 static char *canonical_host_name = NULL;
176
Damien Miller95def091999-11-25 00:26:21 +1100177 /* Check if we have previously retrieved this same name. */
178 if (canonical_host_name != NULL)
179 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000180
Damien Miller95def091999-11-25 00:26:21 +1100181 /* Get the real hostname if socket; otherwise return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100182 if (packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100183 canonical_host_name = get_remote_hostname(packet_get_connection_in());
184 else
185 canonical_host_name = xstrdup("UNKNOWN");
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000186
Damien Miller95def091999-11-25 00:26:21 +1100187 return canonical_host_name;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000188}
189
Damien Miller5428f641999-11-25 11:54:57 +1100190/*
191 * Returns the IP-address of the remote host as a string. The returned
Damien Miller34132e52000-01-14 15:45:46 +1100192 * string must not be freed.
Damien Miller5428f641999-11-25 11:54:57 +1100193 */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000194
Damien Miller95def091999-11-25 00:26:21 +1100195const char *
196get_remote_ipaddr()
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000197{
Damien Miller34132e52000-01-14 15:45:46 +1100198 static char *canonical_host_ip = NULL;
199 struct sockaddr_storage from;
200 socklen_t fromlen;
201 int socket;
202 char ntop[NI_MAXHOST];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000203
Damien Miller5428f641999-11-25 11:54:57 +1100204 /* Check whether we have chached the name. */
Damien Miller95def091999-11-25 00:26:21 +1100205 if (canonical_host_ip != NULL)
206 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000207
Damien Miller95def091999-11-25 00:26:21 +1100208 /* If not a socket, return UNKNOWN. */
Damien Miller34132e52000-01-14 15:45:46 +1100209 if (!packet_connection_is_on_socket()) {
Damien Miller95def091999-11-25 00:26:21 +1100210 canonical_host_ip = xstrdup("UNKNOWN");
211 return canonical_host_ip;
212 }
213 /* Get client socket. */
214 socket = packet_get_connection_in();
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000215
Damien Miller95def091999-11-25 00:26:21 +1100216 /* Get IP address of client. */
217 fromlen = sizeof(from);
218 memset(&from, 0, sizeof(from));
219 if (getpeername(socket, (struct sockaddr *) & from, &fromlen) < 0) {
220 debug("getpeername failed: %.100s", strerror(errno));
221 fatal_cleanup();
222 }
223 /* Get the IP address in ascii. */
Damien Miller34132e52000-01-14 15:45:46 +1100224 if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
225 NULL, 0, NI_NUMERICHOST) != 0)
226 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed");
227
228 canonical_host_ip = xstrdup(ntop);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000229
Damien Miller95def091999-11-25 00:26:21 +1100230 /* Return ip address string. */
231 return canonical_host_ip;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000232}
233
Damien Miller34132e52000-01-14 15:45:46 +1100234/* Returns the local/remote port for the socket. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000235
Damien Miller34132e52000-01-14 15:45:46 +1100236int
237get_sock_port(int sock, int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000238{
Damien Miller34132e52000-01-14 15:45:46 +1100239 struct sockaddr_storage from;
240 socklen_t fromlen;
241 char strport[NI_MAXSERV];
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000242
Damien Miller95def091999-11-25 00:26:21 +1100243 /* Get IP address of client. */
244 fromlen = sizeof(from);
245 memset(&from, 0, sizeof(from));
Damien Miller34132e52000-01-14 15:45:46 +1100246 if (local) {
247 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
248 error("getsockname failed: %.100s", strerror(errno));
249 return 0;
250 }
251 } else {
252 if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
253 debug("getpeername failed: %.100s", strerror(errno));
254 fatal_cleanup();
255 }
Damien Miller95def091999-11-25 00:26:21 +1100256 }
257 /* Return port number. */
Damien Miller34132e52000-01-14 15:45:46 +1100258 if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
259 strport, sizeof(strport), NI_NUMERICSERV) != 0)
260 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
261 return atoi(strport);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000262}
263
Damien Miller34132e52000-01-14 15:45:46 +1100264/* Returns remote/local port number for the current connection. */
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000265
Damien Miller4af51302000-04-16 11:18:38 +1000266int
Damien Miller34132e52000-01-14 15:45:46 +1100267get_port(int local)
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000268{
Damien Miller5428f641999-11-25 11:54:57 +1100269 /*
270 * If the connection is not a socket, return 65535. This is
271 * intentionally chosen to be an unprivileged port number.
272 */
Damien Miller34132e52000-01-14 15:45:46 +1100273 if (!packet_connection_is_on_socket())
Damien Miller95def091999-11-25 00:26:21 +1100274 return 65535;
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000275
Damien Miller34132e52000-01-14 15:45:46 +1100276 /* Get socket and return the port number. */
277 return get_sock_port(packet_get_connection_in(), local);
278}
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000279
Damien Miller4af51302000-04-16 11:18:38 +1000280int
Damien Miller34132e52000-01-14 15:45:46 +1100281get_peer_port(int sock)
282{
283 return get_sock_port(sock, 0);
284}
285
Damien Miller4af51302000-04-16 11:18:38 +1000286int
Damien Miller34132e52000-01-14 15:45:46 +1100287get_remote_port()
288{
289 return get_port(0);
290}
291
292int
293get_local_port()
294{
295 return get_port(1);
Damien Millerd4a8b7e1999-10-27 13:42:43 +1000296}