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(domain, type, protocol)
55 if ((s = socket(domain, type, protocol)) < 0) {
56 tcpd_warn("socket: %m");
59 if ((fp = fdopen(s, "r+")) == 0) {
60 tcpd_warn("fdopen: %m");
67 /* timeout - handle timeouts */
69 static void timeout(int sig)
71 longjmp(timebuf, sig);
74 /* rfc931 - return remote user name, given socket structures */
76 void rfc931(rmt_sin, our_sin, dest)
78 struct sockaddr *rmt_sin;
79 struct sockaddr *our_sin;
81 struct sockaddr_in *rmt_sin;
82 struct sockaddr_in *our_sin;
89 struct sockaddr_storage rmt_query_sin;
90 struct sockaddr_storage our_query_sin;
93 struct sockaddr_in rmt_query_sin;
94 struct sockaddr_in our_query_sin;
96 char user[256]; /* XXX */
97 char buffer[512]; /* XXX */
99 char *result = unknown;
103 /* address family must be the same */
104 if (rmt_sin->sa_family != our_sin->sa_family) {
105 STRN_CPY(dest, result, STRING_LENGTH);
108 switch (our_sin->sa_family) {
110 alen = sizeof(struct sockaddr_in);
113 alen = sizeof(struct sockaddr_in6);
116 STRN_CPY(dest, result, STRING_LENGTH);
122 * If we use a single, buffered, bidirectional stdio stream ("r+" or
123 * "w+" mode) we may read our own output. Such behaviour would make sense
124 * with resources that support random-access operations, but not with
125 * sockets. ANSI C suggests several functions which can be called when
126 * you want to change IO direction, fseek seems the most portable.
130 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
132 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
135 * Set up a timer so we won't get stuck while waiting for the server.
138 if (setjmp(timebuf) == 0) {
139 signal(SIGALRM, timeout);
140 alarm(rfc931_timeout);
143 * Bind the local and remote ends of the query socket to the same
144 * IP addresses as the connection under investigation. We go
145 * through all this trouble because the local or remote system
146 * might have more than one network address. The RFC931 etc.
147 * client sends only port numbers; the server takes the IP
148 * addresses from the query socket.
152 memcpy(&our_query_sin, our_sin, alen);
153 memcpy(&rmt_query_sin, rmt_sin, alen);
154 switch (our_sin->sa_family) {
156 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT);
157 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT);
160 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT);
161 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT);
165 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
167 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
170 our_query_sin = *our_sin;
171 our_query_sin.sin_port = htons(ANY_PORT);
172 rmt_query_sin = *rmt_sin;
173 rmt_query_sin.sin_port = htons(RFC931_PORT);
175 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
176 sizeof(our_query_sin)) >= 0 &&
177 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
178 sizeof(rmt_query_sin)) >= 0) {
182 * Send query to server. Neglect the risk that a 13-byte
183 * write would have to be fragmented by the local system and
184 * cause trouble with buggy System V stdio libraries.
187 fprintf(fp, "%u,%u\r\n",
189 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port),
190 ntohs(((struct sockaddr_in *)our_sin)->sin_port));
192 ntohs(rmt_sin->sin_port),
193 ntohs(our_sin->sin_port));
196 fseek(fp, 0, SEEK_SET);
199 * Read response from server. Use fgets()/sscanf() so we can
200 * work around System V stdio libraries that incorrectly
201 * assume EOF when a read from a socket returns less than
205 if (fgets(buffer, sizeof(buffer), fp) != 0
206 && ferror(fp) == 0 && feof(fp) == 0
207 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
208 &rmt_port, &our_port, user) == 3
210 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port
211 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) {
213 && ntohs(rmt_sin->sin_port) == rmt_port
214 && ntohs(our_sin->sin_port) == our_port) {
218 * Strip trailing carriage return. It is part of the
219 * protocol, not part of the data.
222 if (cp = strchr(user, '\r'))
231 STRN_CPY(dest, result, STRING_LENGTH);