1 /*
2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
4 * All rights reserved
5 * Functions for returning the canonical host name of the remote site.
6 *
7 * 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".
12 */
13 /*
14 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
15 * Use is subject to license terms.
16 *
17 * Copyright 2012 Nexenta Systems, Inc. All rights reserved.
18 */
19
20 #include "includes.h"
21 RCSID("$OpenBSD: canohost.c,v 1.34 2002/09/23 20:46:27 stevesk Exp $");
22
23 #include "packet.h"
24 #include "xmalloc.h"
25 #include "log.h"
26 #include "canohost.h"
27
28 static const char *inet_ntop_native(int af, const void *src,
29 char *dst, size_t size);
30
31
32 /*
33 * Return the canonical name of the host at the other end of the socket. The
34 * caller should free the returned string with xfree.
35 */
36
37 static char *
get_remote_hostname(int socket,int verify_reverse_mapping)38 get_remote_hostname(int socket, int verify_reverse_mapping)
39 {
40 struct sockaddr_storage from;
41 int i, res;
42 socklen_t fromlen;
43 struct addrinfo hints, *ai, *aitop;
44 char name[NI_MAXHOST], ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
45
46 /* Get IP address of client. */
47 fromlen = sizeof(from);
48 memset(&from, 0, sizeof(from));
49 if (getpeername(socket, (struct sockaddr *) &from, &fromlen) < 0) {
50 debug("getpeername failed: %.100s", strerror(errno));
51 fatal_cleanup();
52 }
53
54 if ((res = getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop),
55 NULL, 0, NI_NUMERICHOST)) != 0)
56 fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed: %d", res);
57
58 #ifdef IPV4_IN_IPV6
59 if (from.ss_family == AF_INET6) {
60 struct sockaddr_in6 *from6 = (struct sockaddr_in6 *)&from;
61
62 (void) inet_ntop_native(from.ss_family,
63 from6->sin6_addr.s6_addr,
64 ntop, sizeof(ntop));
65 }
66 #endif /* IPV4_IN_IPV6 */
67
68 if (!verify_reverse_mapping)
69 return xstrdup(ntop);
70
71 debug3("Trying to reverse map address %.100s.", ntop);
72 /* Map the IP address to a host name. */
73 if (getnameinfo((struct sockaddr *)&from, fromlen, name, sizeof(name),
74 NULL, 0, NI_NAMEREQD) != 0) {
75 /* Host name not found. Use ip address. */
76 #if 0
77 log("Could not reverse map address %.100s.", ntop);
78 #endif
79 return xstrdup(ntop);
80 }
81
82 /* Got host name. */
83 name[sizeof(name) - 1] = '\0';
84 /*
85 * Convert it to all lowercase (which is expected by the rest
86 * of this software).
87 */
88 for (i = 0; name[i]; i++)
89 if (isupper(name[i]))
90 name[i] = tolower(name[i]);
91
92 /*
93 * Map it back to an IP address and check that the given
94 * address actually is an address of this host. This is
95 * necessary because anyone with access to a name server can
96 * define arbitrary names for an IP address. Mapping from
97 * name to IP address can be trusted better (but can still be
98 * fooled if the intruder has access to the name server of
99 * the domain).
100 */
101 memset(&hints, 0, sizeof(hints));
102 hints.ai_family = from.ss_family;
103 hints.ai_socktype = SOCK_STREAM;
104 if (getaddrinfo(name, NULL, &hints, &aitop) != 0) {
105 log("reverse mapping checking getaddrinfo for %.700s "
106 "failed - POSSIBLE BREAKIN ATTEMPT!", name);
107 return xstrdup(ntop);
108 }
109 /* Look for the address from the list of addresses. */
110 for (ai = aitop; ai; ai = ai->ai_next) {
111 if (getnameinfo(ai->ai_addr, ai->ai_addrlen, ntop2,
112 sizeof(ntop2), NULL, 0, NI_NUMERICHOST) == 0 &&
113 (strcmp(ntop, ntop2) == 0))
114 break;
115 }
116 freeaddrinfo(aitop);
117 /* If we reached the end of the list, the address was not there. */
118 if (!ai) {
119 /* Address not found for the host name. */
120 log("Address %.100s maps to %.600s, but this does not "
121 "map back to the address - POSSIBLE BREAKIN ATTEMPT!",
122 ntop, name);
123 return xstrdup(ntop);
124 }
125 return xstrdup(name);
126 }
127
128 /*
129 * Return the canonical name of the host in the other side of the current
130 * connection. The host name is cached, so it is efficient to call this
131 * several times.
132 */
133
134 const char *
get_canonical_hostname(int verify_reverse_mapping)135 get_canonical_hostname(int verify_reverse_mapping)
136 {
137 static char *canonical_host_name = NULL;
138 static int verify_reverse_mapping_done = 0;
139
140 /* Check if we have previously retrieved name with same option. */
141 if (canonical_host_name != NULL) {
142 if (verify_reverse_mapping_done != verify_reverse_mapping)
143 xfree(canonical_host_name);
144 else
145 return canonical_host_name;
146 }
147
148 /* Get the real hostname if socket; otherwise return UNKNOWN. */
149 if (packet_connection_is_on_socket())
150 canonical_host_name = get_remote_hostname(
151 packet_get_connection_in(), verify_reverse_mapping);
152 else
153 canonical_host_name = xstrdup("UNKNOWN");
154
155 verify_reverse_mapping_done = verify_reverse_mapping;
156 return canonical_host_name;
157 }
158
159 /*
160 * Returns the remote IP-address of socket as a string. The returned
161 * string must be freed.
162 */
163 char *
get_socket_address(int socket,int remote,int flags)164 get_socket_address(int socket, int remote, int flags)
165 {
166 struct sockaddr_storage addr;
167 struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)&addr;
168 socklen_t addrlen;
169 char ntop[NI_MAXHOST];
170 const char *result;
171 char abuf[INET6_ADDRSTRLEN];
172
173 /* Get IP address of client. */
174 addrlen = sizeof (addr);
175 memset(&addr, 0, sizeof (addr));
176
177 if (remote) {
178 if (getpeername(socket, (struct sockaddr *)&addr, &addrlen)
179 < 0) {
180 debug("get_socket_ipaddr: getpeername failed: %.100s",
181 strerror(errno));
182 return (NULL);
183 }
184 } else {
185 if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
186 < 0) {
187 debug("get_socket_ipaddr: getsockname failed: %.100s",
188 strerror(errno));
189 return (NULL);
190 }
191 }
192
193 /* Get the address in ascii. */
194 if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof (ntop),
195 NULL, 0, flags) != 0) {
196 error("get_socket_ipaddr: getnameinfo %d failed", flags);
197 return (NULL);
198 }
199
200 if (addr.ss_family == AF_INET) {
201 return (xstrdup(ntop));
202 }
203
204 result = inet_ntop_native(addr.ss_family,
205 addr6->sin6_addr.s6_addr, abuf, sizeof (abuf));
206
207 return (xstrdup(result));
208 }
209 #if 0
210 static char *
211 get_socket_address(int socket, int remote, int flags)
212 {
213 struct sockaddr_storage addr;
214 socklen_t addrlen;
215 char ntop[NI_MAXHOST];
216
217 /* Get IP address of client. */
218 addrlen = sizeof(addr);
219 memset(&addr, 0, sizeof(addr));
220
221 if (remote) {
222 if (getpeername(socket, (struct sockaddr *)&addr, &addrlen)
223 < 0)
224 return NULL;
225 } else {
226 if (getsockname(socket, (struct sockaddr *)&addr, &addrlen)
227 < 0)
228 return NULL;
229 }
230 /* Get the address in ascii. */
231 if (getnameinfo((struct sockaddr *)&addr, addrlen, ntop, sizeof(ntop),
232 NULL, 0, flags) != 0) {
233 error("get_socket_ipaddr: getnameinfo %d failed", flags);
234 return NULL;
235 }
236 return xstrdup(ntop);
237 }
238 #endif
239
240 char *
get_peer_ipaddr(int socket)241 get_peer_ipaddr(int socket)
242 {
243 char *p;
244
245 if ((p = get_socket_address(socket, 1, NI_NUMERICHOST)) != NULL)
246 return p;
247 return xstrdup("UNKNOWN");
248 }
249
250 char *
get_local_ipaddr(int socket)251 get_local_ipaddr(int socket)
252 {
253 char *p;
254
255 if ((p = get_socket_address(socket, 0, NI_NUMERICHOST)) != NULL)
256 return p;
257 return xstrdup("UNKNOWN");
258 }
259
260 char *
get_local_name(int socket)261 get_local_name(int socket)
262 {
263 return get_socket_address(socket, 0, NI_NAMEREQD);
264 }
265
266 /*
267 * Returns the IP-address of the remote host as a string. The returned
268 * string must not be freed.
269 */
270
271 const char *
get_remote_ipaddr(void)272 get_remote_ipaddr(void)
273 {
274 static char *canonical_host_ip = NULL;
275
276 /* Check whether we have cached the ipaddr. */
277 if (canonical_host_ip == NULL) {
278 if (packet_connection_is_on_socket()) {
279 canonical_host_ip =
280 get_peer_ipaddr(packet_get_connection_in());
281 if (canonical_host_ip == NULL)
282 fatal_cleanup();
283 } else {
284 /* If not on socket, return UNKNOWN. */
285 canonical_host_ip = xstrdup("UNKNOWN");
286 }
287 }
288 return canonical_host_ip;
289 }
290
291 const char *
get_remote_name_or_ip(u_int utmp_len,int verify_reverse_mapping)292 get_remote_name_or_ip(u_int utmp_len, int verify_reverse_mapping)
293 {
294 static const char *remote = "";
295 if (utmp_len > 0)
296 remote = get_canonical_hostname(verify_reverse_mapping);
297 if (utmp_len == 0 || strlen(remote) > utmp_len)
298 remote = get_remote_ipaddr();
299 return remote;
300 }
301
302 /* Returns the local/remote port for the socket. */
303
304 static int
get_sock_port(int sock,int local)305 get_sock_port(int sock, int local)
306 {
307 struct sockaddr_storage from;
308 socklen_t fromlen;
309 char strport[NI_MAXSERV];
310
311 /* Get IP address of client. */
312 fromlen = sizeof(from);
313 memset(&from, 0, sizeof(from));
314 if (local) {
315 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
316 error("getsockname failed: %.100s", strerror(errno));
317 return 0;
318 }
319 } else {
320 if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
321 debug("getpeername failed: %.100s", strerror(errno));
322 fatal_cleanup();
323 }
324 }
325 /* Return port number. */
326 if (getnameinfo((struct sockaddr *)&from, fromlen, NULL, 0,
327 strport, sizeof(strport), NI_NUMERICSERV) != 0)
328 fatal("get_sock_port: getnameinfo NI_NUMERICSERV failed");
329 return atoi(strport);
330 }
331
332 /* Returns remote/local port number for the current connection. */
333
334 static int
get_port(int local)335 get_port(int local)
336 {
337 /*
338 * If the connection is not a socket, return 65535. This is
339 * intentionally chosen to be an unprivileged port number.
340 */
341 if (!packet_connection_is_on_socket())
342 return 65535;
343
344 /* Get socket and return the port number. */
345 return get_sock_port(packet_get_connection_in(), local);
346 }
347
348 int
get_peer_port(int sock)349 get_peer_port(int sock)
350 {
351 return get_sock_port(sock, 0);
352 }
353
354 int
get_remote_port(void)355 get_remote_port(void)
356 {
357 return get_port(0);
358 }
359
360 int
get_local_port(void)361 get_local_port(void)
362 {
363 return get_port(1);
364 }
365
366 /*
367 * Taken from inetd.c
368 * This is a wrapper function for inet_ntop(). In case the af is AF_INET6
369 * and the address pointed by src is a IPv4-mapped IPv6 address, it
370 * returns printable IPv4 address, not IPv4-mapped IPv6 address. In other cases
371 * it behaves just like inet_ntop().
372 */
373 static const char *
inet_ntop_native(int af,const void * src,char * dst,size_t size)374 inet_ntop_native(int af, const void *src, char *dst, size_t size)
375 {
376 struct in_addr src4;
377 const char *result;
378
379 if (af == AF_INET6) {
380 if (IN6_IS_ADDR_V4MAPPED((struct in6_addr *)src)) {
381 IN6_V4MAPPED_TO_INADDR((struct in6_addr *)src, &src4);
382 result = inet_ntop(AF_INET, &src4, dst, size);
383 } else {
384 result = inet_ntop(AF_INET6, src, dst, size);
385 }
386 } else {
387 result = inet_ntop(af, src, dst, size);
388 }
389
390 return (result);
391 }
392