2 * rfc931() speaks a common subset of the RFC 931, AUTH, TAP, IDENT and RFC
3 * 1413 protocols. It queries an RFC 931 etc. compatible daemon on a remote
4 * host to look up the owner of a connection. The information should not be
5 * used for authentication purposes. This routine intercepts alarm signals.
7 * Diagnostics are reported through syslog(3).
9 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
15 static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
18 /* System libraries. */
22 #include <sys/types.h>
23 #include <sys/socket.h>
24 #include <netinet/in.h>
38 #define RFC931_PORT 113 /* Semi-well-known port */
39 #define ANY_PORT 0 /* Any old port will do */
41 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */
43 static jmp_buf timebuf;
45 /* fsocket - open stdio stream on top of socket */
47 static FILE *fsocket(int domain, int type, int protocol)
52 if ((s = socket(domain, type, protocol)) < 0) {
53 tcpd_warn("socket: %m");
56 if ((fp = fdopen(s, "r+")) == 0) {
57 tcpd_warn("fdopen: %m");
64 /* timeout - handle timeouts */
66 static void timeout(int sig)
68 longjmp(timebuf, sig);
71 /* rfc931 - return remote user name, given socket structures */
74 void rfc931(struct sockaddr *rmt_sin, struct sockaddr *our_sin, char *dest)
76 void rfc931(struct sockaddr_in *rmt_sin, struct sockaddr_in *our_sin,
83 struct sockaddr_storage rmt_query_sin;
84 struct sockaddr_storage our_query_sin;
87 struct sockaddr_in rmt_query_sin;
88 struct sockaddr_in our_query_sin;
90 char user[256]; /* XXX */
91 char buffer[512]; /* XXX */
93 char *result = unknown;
97 /* address family must be the same */
98 if (rmt_sin->sa_family != our_sin->sa_family) {
99 STRN_CPY(dest, result, STRING_LENGTH);
102 switch (our_sin->sa_family) {
104 alen = sizeof(struct sockaddr_in);
107 alen = sizeof(struct sockaddr_in6);
110 STRN_CPY(dest, result, STRING_LENGTH);
116 * If we use a single, buffered, bidirectional stdio stream ("r+" or
117 * "w+" mode) we may read our own output. Such behaviour would make sense
118 * with resources that support random-access operations, but not with
119 * sockets. ANSI C suggests several functions which can be called when
120 * you want to change IO direction, fseek seems the most portable.
124 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
126 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
129 * Set up a timer so we won't get stuck while waiting for the server.
132 if (setjmp(timebuf) == 0) {
133 signal(SIGALRM, timeout);
134 alarm(rfc931_timeout);
137 * Bind the local and remote ends of the query socket to the same
138 * IP addresses as the connection under investigation. We go
139 * through all this trouble because the local or remote system
140 * might have more than one network address. The RFC931 etc.
141 * client sends only port numbers; the server takes the IP
142 * addresses from the query socket.
146 memcpy(&our_query_sin, our_sin, alen);
147 memcpy(&rmt_query_sin, rmt_sin, alen);
148 switch (our_sin->sa_family) {
150 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT);
151 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT);
154 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT);
155 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT);
159 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
161 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
164 our_query_sin = *our_sin;
165 our_query_sin.sin_port = htons(ANY_PORT);
166 rmt_query_sin = *rmt_sin;
167 rmt_query_sin.sin_port = htons(RFC931_PORT);
169 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
170 sizeof(our_query_sin)) >= 0 &&
171 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
172 sizeof(rmt_query_sin)) >= 0) {
176 * Send query to server. Neglect the risk that a 13-byte
177 * write would have to be fragmented by the local system and
178 * cause trouble with buggy System V stdio libraries.
181 fprintf(fp, "%u,%u\r\n",
183 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port),
184 ntohs(((struct sockaddr_in *)our_sin)->sin_port));
186 ntohs(rmt_sin->sin_port),
187 ntohs(our_sin->sin_port));
190 fseek(fp, 0, SEEK_SET);
193 * Read response from server. Use fgets()/sscanf() so we can
194 * work around System V stdio libraries that incorrectly
195 * assume EOF when a read from a socket returns less than
199 if (fgets(buffer, sizeof(buffer), fp) != 0
200 && ferror(fp) == 0 && feof(fp) == 0
201 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
202 &rmt_port, &our_port, user) == 3
204 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port
205 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) {
207 && ntohs(rmt_sin->sin_port) == rmt_port
208 && ntohs(our_sin->sin_port) == our_port) {
212 * Strip trailing carriage return. It is part of the
213 * protocol, not part of the data.
216 if (cp = strchr(user, '\r'))
225 STRN_CPY(dest, result, STRING_LENGTH);