5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 * Created: Sun Jul 2 17:52:22 1995 ylo
12 * Functions for returning the canonical host name of the remote site.
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.
29 get_remote_hostname(int socket)
31 struct sockaddr_storage from;
34 struct addrinfo hints, *ai, *aitop;
35 char name[MAXHOSTNAMELEN];
36 char ntop[NI_MAXHOST], ntop2[NI_MAXHOST];
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));
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");
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) {
53 name[sizeof(name) - 1] = '\0';
55 * Convert it to all lowercase (which is expected by the rest
58 for (i = 0; name[i]; i++)
60 name[i] = tolower(name[i]);
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
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);
77 goto check_ip_options;
79 /* Look for the address from the list of addresses. */
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))
87 /* If we reached the end of the list, the address was not there. */
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!",
92 strlcpy(name, ntop, sizeof name);
93 goto check_ip_options;
95 /* Address was found for the host name. We accept the host name. */
97 /* Host name not found. Use ascii representation of the address. */
98 strlcpy(name, ntop, sizeof name);
99 log("Could not reverse map address %.100s.", name);
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.
115 /* IP options -- IPv4 only */
116 if (from.ss_family == AF_INET) {
117 unsigned char options[200], *ucp;
118 char text[1024], *cp;
119 socklen_t option_size;
123 if ((ip = getprotobyname("ip")) != NULL)
124 ipproto = ip->p_proto;
126 ipproto = IPPROTO_IP;
127 option_size = sizeof(options);
128 if (getsockopt(0, ipproto, IP_OPTIONS, (char *) options,
129 &option_size) >= 0 && option_size != 0) {
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",
136 packet_disconnect("Connection from %.100s with IP options:%.800s",
141 return xstrdup(name);
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
151 get_canonical_hostname()
153 static char *canonical_host_name = NULL;
155 /* Check if we have previously retrieved this same name. */
156 if (canonical_host_name != NULL)
157 return canonical_host_name;
159 /* Get the real hostname if socket; otherwise return UNKNOWN. */
160 if (packet_connection_is_on_socket())
161 canonical_host_name = get_remote_hostname(packet_get_connection_in());
163 canonical_host_name = xstrdup("UNKNOWN");
165 return canonical_host_name;
169 * Returns the IP-address of the remote host as a string. The returned
170 * string must not be freed.
176 static char *canonical_host_ip = NULL;
177 struct sockaddr_storage from;
180 char ntop[NI_MAXHOST];
182 /* Check whether we have chached the name. */
183 if (canonical_host_ip != NULL)
184 return canonical_host_ip;
186 /* If not a socket, return UNKNOWN. */
187 if (!packet_connection_is_on_socket()) {
188 canonical_host_ip = xstrdup("UNKNOWN");
189 return canonical_host_ip;
191 /* Get client socket. */
192 socket = packet_get_connection_in();
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));
201 /* Get the IP address in ascii. */
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");
206 canonical_host_ip = xstrdup(ntop);
208 /* Return ip address string. */
209 return canonical_host_ip;
212 /* Returns the local/remote port for the socket. */
215 get_sock_port(int sock, int local)
217 struct sockaddr_storage from;
219 char strport[NI_MAXSERV];
221 /* Get IP address of client. */
222 fromlen = sizeof(from);
223 memset(&from, 0, sizeof(from));
225 if (getsockname(sock, (struct sockaddr *)&from, &fromlen) < 0) {
226 error("getsockname failed: %.100s", strerror(errno));
230 if (getpeername(sock, (struct sockaddr *) & from, &fromlen) < 0) {
231 debug("getpeername failed: %.100s", strerror(errno));
235 /* Return port number. */
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);
242 /* Returns remote/local port number for the current connection. */
248 * If the connection is not a socket, return 65535. This is
249 * intentionally chosen to be an unprivileged port number.
251 if (!packet_connection_is_on_socket())
254 /* Get socket and return the port number. */
255 return get_sock_port(packet_get_connection_in(), local);
259 get_peer_port(int sock)
261 return get_sock_port(sock, 0);