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Commit | Line | Data |
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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 * |
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 | } | |
48e671d5 | 45 | if (getnameinfo((struct sockaddr *)&from, fromlen, ntop, sizeof(ntop), |
46 | NULL, 0, NI_NUMERICHOST) != 0) | |
47 | fatal("get_remote_hostname: getnameinfo NI_NUMERICHOST failed"); | |
5260325f | 48 | |
48e671d5 | 49 | /* 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'; | |
aa3378df | 54 | /* |
55 | * Convert it to all lowercase (which is expected by the rest | |
56 | * of this software). | |
57 | */ | |
5260325f | 58 | for (i = 0; name[i]; i++) |
59 | if (isupper(name[i])) | |
60 | name[i] = tolower(name[i]); | |
61 | ||
aa3378df | 62 | /* |
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 | */ | |
48e671d5 | 71 | 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); | |
5260325f | 77 | goto check_ip_options; |
78 | } | |
79 | /* Look for the address from the list of addresses. */ | |
48e671d5 | 80 | 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) { | |
5260325f | 89 | /* 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!", | |
48e671d5 | 91 | ntop, name); |
92 | strlcpy(name, ntop, sizeof name); | |
5260325f | 93 | 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. */ | |
48e671d5 | 98 | strlcpy(name, ntop, sizeof name); |
5260325f | 99 | log("Could not reverse map address %.100s.", name); |
8efc0c15 | 100 | } |
5260325f | 101 | |
102 | check_ip_options: | |
103 | ||
aa3378df | 104 | /* |
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 | */ | |
48e671d5 | 115 | /* IP options -- IPv4 only */ |
116 | if (from.ss_family == AF_INET) { | |
5260325f | 117 | unsigned char options[200], *ucp; |
118 | char text[1024], *cp; | |
48e671d5 | 119 | socklen_t option_size; |
120 | int ipproto; | |
5260325f | 121 | 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, | |
48e671d5 | 129 | &option_size) >= 0 && option_size != 0) { |
5260325f | 130 | 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", | |
48e671d5 | 135 | ntop, text); |
5260325f | 136 | packet_disconnect("Connection from %.100s with IP options:%.800s", |
48e671d5 | 137 | ntop, text); |
5260325f | 138 | } |
8efc0c15 | 139 | } |
5260325f | 140 | |
141 | return xstrdup(name); | |
8efc0c15 | 142 | } |
143 | ||
aa3378df | 144 | /* |
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 | */ | |
8efc0c15 | 149 | |
5260325f | 150 | const char * |
151 | get_canonical_hostname() | |
8efc0c15 | 152 | { |
48e671d5 | 153 | static char *canonical_host_name = NULL; |
154 | ||
5260325f | 155 | /* Check if we have previously retrieved this same name. */ |
156 | if (canonical_host_name != NULL) | |
157 | return canonical_host_name; | |
8efc0c15 | 158 | |
5260325f | 159 | /* Get the real hostname if socket; otherwise return UNKNOWN. */ |
48e671d5 | 160 | if (packet_connection_is_on_socket()) |
5260325f | 161 | canonical_host_name = get_remote_hostname(packet_get_connection_in()); |
162 | else | |
163 | canonical_host_name = xstrdup("UNKNOWN"); | |
8efc0c15 | 164 | |
5260325f | 165 | return canonical_host_name; |
8efc0c15 | 166 | } |
167 | ||
aa3378df | 168 | /* |
169 | * Returns the IP-address of the remote host as a string. The returned | |
48e671d5 | 170 | * string must not be freed. |
aa3378df | 171 | */ |
8efc0c15 | 172 | |
5260325f | 173 | const char * |
174 | get_remote_ipaddr() | |
8efc0c15 | 175 | { |
48e671d5 | 176 | static char *canonical_host_ip = NULL; |
177 | struct sockaddr_storage from; | |
178 | socklen_t fromlen; | |
179 | int socket; | |
180 | char ntop[NI_MAXHOST]; | |
5260325f | 181 | |
aa3378df | 182 | /* Check whether we have chached the name. */ |
5260325f | 183 | if (canonical_host_ip != NULL) |
184 | return canonical_host_ip; | |
185 | ||
186 | /* If not a socket, return UNKNOWN. */ | |
48e671d5 | 187 | if (!packet_connection_is_on_socket()) { |
5260325f | 188 | canonical_host_ip = xstrdup("UNKNOWN"); |
189 | return canonical_host_ip; | |
190 | } | |
191 | /* Get client socket. */ | |
192 | socket = packet_get_connection_in(); | |
193 | ||
194 | /* 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. */ | |
48e671d5 | 202 | 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); | |
5260325f | 207 | |
208 | /* Return ip address string. */ | |
209 | return canonical_host_ip; | |
8efc0c15 | 210 | } |
211 | ||
48e671d5 | 212 | /* Returns the local/remote port for the socket. */ |
8efc0c15 | 213 | |
48e671d5 | 214 | int |
215 | get_sock_port(int sock, int local) | |
8efc0c15 | 216 | { |
48e671d5 | 217 | struct sockaddr_storage from; |
218 | socklen_t fromlen; | |
219 | char strport[NI_MAXSERV]; | |
5260325f | 220 | |
221 | /* Get IP address of client. */ | |
222 | fromlen = sizeof(from); | |
223 | memset(&from, 0, sizeof(from)); | |
48e671d5 | 224 | 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 | } | |
5260325f | 234 | } |
235 | /* Return port number. */ | |
48e671d5 | 236 | 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); | |
8efc0c15 | 240 | } |
241 | ||
48e671d5 | 242 | /* Returns remote/local port number for the current connection. */ |
8efc0c15 | 243 | |
5260325f | 244 | int |
48e671d5 | 245 | get_port(int local) |
8efc0c15 | 246 | { |
aa3378df | 247 | /* |
248 | * If the connection is not a socket, return 65535. This is | |
249 | * intentionally chosen to be an unprivileged port number. | |
250 | */ | |
48e671d5 | 251 | if (!packet_connection_is_on_socket()) |
5260325f | 252 | return 65535; |
8efc0c15 | 253 | |
48e671d5 | 254 | /* Get socket and return the port number. */ |
255 | return get_sock_port(packet_get_connection_in(), local); | |
256 | } | |
257 | ||
258 | int | |
259 | get_peer_port(int sock) | |
260 | { | |
261 | return get_sock_port(sock, 0); | |
262 | } | |
8efc0c15 | 263 | |
48e671d5 | 264 | int |
265 | get_remote_port() | |
266 | { | |
267 | return get_port(0); | |
268 | } | |
269 | ||
270 | int | |
271 | get_local_port() | |
272 | { | |
273 | return get_port(1); | |
8efc0c15 | 274 | } |