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8efc0c15 | 1 | /* |
5260325f | 2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> |
5260325f | 3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland |
4 | * All rights reserved | |
5260325f | 5 | * Functions for returning the canonical host name of the remote site. |
6ae2364d | 6 | * |
bcbf86ec | 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". | |
5260325f | 12 | */ |
8efc0c15 | 13 | |
14 | #include "includes.h" | |
42f11eb2 | 15 | RCSID("$OpenBSD: canohost.c,v 1.18 2001/01/21 19:05:45 markus Exp $"); |
8efc0c15 | 16 | |
17 | #include "packet.h" | |
18 | #include "xmalloc.h" | |
42f11eb2 | 19 | #include "log.h" |
8efc0c15 | 20 | |
aa3378df | 21 | /* |
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 | */ | |
8efc0c15 | 25 | |
5260325f | 26 | char * |
27 | get_remote_hostname(int socket) | |
8efc0c15 | 28 | { |
48e671d5 | 29 | struct sockaddr_storage from; |
30 | int i; | |
31 | socklen_t fromlen; | |
32 | struct addrinfo hints, *ai, *aitop; | |
5260325f | 33 | char name[MAXHOSTNAMELEN]; |
48e671d5 | 34 | char ntop[NI_MAXHOST], ntop2[NI_MAXHOST]; |
5260325f | 35 | |
36 | /* 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(); | |
42 | } | |
80faa19f | 43 | |
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 | ||
48e671d5 | 67 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
68 | NULL, 0, NI_NUMERICHOST) != 0) | |
69 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); | |
5260325f | 70 | |
48e671d5 | 71 | /* 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'; | |
aa3378df | 76 | /* |
77 | * Convert it to all lowercase (which is expected by the rest | |
78 | * of this software). | |
79 | */ | |
5260325f | 80 | for (i = 0; name[i]; i++) |
81 | if (isupper(name[i])) | |
82 | name[i] = tolower(name[i]); | |
83 | ||
aa3378df | 84 | /* |
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 | */ | |
48e671d5 | 93 | 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); | |
5260325f | 99 | goto check_ip_options; |
100 | } | |
101 | /* Look for the address from the list of addresses. */ | |
48e671d5 | 102 | 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) { | |
5260325f | 111 | /* 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!", | |
48e671d5 | 113 | ntop, name); |
114 | strlcpy(name, ntop, sizeof name); | |
5260325f | 115 | 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. */ | |
48e671d5 | 120 | strlcpy(name, ntop, sizeof name); |
5260325f | 121 | log("Could not reverse map address %.100s.", name); |
8efc0c15 | 122 | } |
5260325f | 123 | |
124 | check_ip_options: | |
125 | ||
aa3378df | 126 | /* |
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 | */ | |
48e671d5 | 137 | /* IP options -- IPv4 only */ |
138 | if (from.ss_family == AF_INET) { | |
1e3b8b07 | 139 | u_char options[200], *ucp; |
5260325f | 140 | char text[1024], *cp; |
48e671d5 | 141 | socklen_t option_size; |
142 | int ipproto; | |
5260325f | 143 | 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); | |
a22aff1f | 150 | if (getsockopt(socket, ipproto, IP_OPTIONS, (char *) options, |
48e671d5 | 151 | &option_size) >= 0 && option_size != 0) { |
5260325f | 152 | 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", | |
48e671d5 | 157 | ntop, text); |
5260325f | 158 | packet_disconnect("Connection from %.100s with IP options:%.800s", |
48e671d5 | 159 | ntop, text); |
5260325f | 160 | } |
8efc0c15 | 161 | } |
5260325f | 162 | |
163 | return xstrdup(name); | |
8efc0c15 | 164 | } |
165 | ||
aa3378df | 166 | /* |
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 | */ | |
8efc0c15 | 171 | |
5260325f | 172 | const char * |
173 | get_canonical_hostname() | |
8efc0c15 | 174 | { |
48e671d5 | 175 | static char *canonical_host_name = NULL; |
176 | ||
5260325f | 177 | /* Check if we have previously retrieved this same name. */ |
178 | if (canonical_host_name != NULL) | |
179 | return canonical_host_name; | |
8efc0c15 | 180 | |
5260325f | 181 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 182 | if (packet_connection_is_on_socket()) |
5260325f | 183 | canonical_host_name = get_remote_hostname(packet_get_connection_in()); |
184 | else | |
185 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 186 | |
5260325f | 187 | return canonical_host_name; |
8efc0c15 | 188 | } |
189 | ||
aa3378df | 190 | /* |
191 | * Returns the IP-address of the remote host as a string. The returned | |
48e671d5 | 192 | * string must not be freed. |
aa3378df | 193 | */ |
8efc0c15 | 194 | |
5260325f | 195 | const char * |
196 | get_remote_ipaddr() | |
8efc0c15 | 197 | { |
48e671d5 | 198 | static char *canonical_host_ip = NULL; |
199 | struct sockaddr_storage from; | |
200 | socklen_t fromlen; | |
201 | int socket; | |
202 | char ntop[NI_MAXHOST]; | |
5260325f | 203 | |
aa3378df | 204 | /* Check whether we have chached the name. */ |
5260325f | 205 | if (canonical_host_ip != NULL) |
206 | return canonical_host_ip; | |
207 | ||
208 | /* If not a socket, return UNKNOWN. */ | |
48e671d5 | 209 | if (!packet_connection_is_on_socket()) { |
5260325f | 210 | canonical_host_ip = xstrdup("UNKNOWN"); |
211 | return canonical_host_ip; | |
212 | } | |
213 | /* Get client socket. */ | |
214 | socket = packet_get_connection_in(); | |
215 | ||
216 | /* 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. */ | |
48e671d5 | 224 | 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); | |
5260325f | 229 | |
230 | /* Return ip address string. */ | |
231 | return canonical_host_ip; | |
8efc0c15 | 232 | } |
233 | ||
48e671d5 | 234 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 235 | |
48e671d5 | 236 | int |
237 | get_sock_port(int sock, int local) | |
8efc0c15 | 238 | { |
48e671d5 | 239 | struct sockaddr_storage from; |
240 | socklen_t fromlen; | |
241 | char strport[NI_MAXSERV]; | |
5260325f | 242 | |
243 | /* Get IP address of client. */ | |
244 | fromlen = sizeof(from); | |
245 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 246 | 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 | } | |
5260325f | 256 | } |
257 | /* Return port number. */ | |
48e671d5 | 258 | 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); | |
8efc0c15 | 262 | } |
263 | ||
48e671d5 | 264 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 265 | |
6ae2364d | 266 | int |
48e671d5 | 267 | get_port(int local) |
8efc0c15 | 268 | { |
aa3378df | 269 | /* |
270 | * If the connection is not a socket, return 65535. This is | |
271 | * intentionally chosen to be an unprivileged port number. | |
272 | */ | |
48e671d5 | 273 | if (!packet_connection_is_on_socket()) |
5260325f | 274 | return 65535; |
8efc0c15 | 275 | |
48e671d5 | 276 | /* Get socket and return the port number. */ |
277 | return get_sock_port(packet_get_connection_in(), local); | |
278 | } | |
279 | ||
6ae2364d | 280 | int |
48e671d5 | 281 | get_peer_port(int sock) |
282 | { | |
283 | return get_sock_port(sock, 0); | |
284 | } | |
8efc0c15 | 285 | |
6ae2364d | 286 | int |
48e671d5 | 287 | get_remote_port() |
288 | { | |
289 | return get_port(0); | |
290 | } | |
291 | ||
292 | int | |
293 | get_local_port() | |
294 | { | |
295 | return get_port(1); | |
8efc0c15 | 296 | } |