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.
11 * $FreeBSD: src/contrib/tcp_wrappers/rfc931.c,v 1.2.2.1 2000/07/18 16:41:11 dwmalone Exp $
14 /* System libraries. */
18 #include <sys/types.h>
19 #include <sys/socket.h>
20 #include <netinet/in.h>
34 #define RFC931_PORT 113 /* Semi-well-known port */
35 #define ANY_PORT 0 /* Any old port will do */
37 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */
39 static jmp_buf timebuf;
41 /* fsocket - open stdio stream on top of socket */
43 static FILE *fsocket(domain, type, protocol)
51 if ((s = socket(domain, type, protocol)) < 0) {
52 tcpd_warn("socket: %m");
55 if ((fp = fdopen(s, "r+")) == 0) {
56 tcpd_warn("fdopen: %m");
63 /* timeout - handle timeouts */
65 static void timeout(sig)
68 longjmp(timebuf, sig);
71 /* rfc931 - return remote user name, given socket structures */
73 void rfc931(rmt_sin, our_sin, dest)
75 struct sockaddr *rmt_sin;
76 struct sockaddr *our_sin;
78 struct sockaddr_in *rmt_sin;
79 struct sockaddr_in *our_sin;
86 struct sockaddr_storage rmt_query_sin;
87 struct sockaddr_storage our_query_sin;
90 struct sockaddr_in rmt_query_sin;
91 struct sockaddr_in our_query_sin;
93 char user[256]; /* XXX */
94 char buffer[512]; /* XXX */
96 char *result = unknown;
100 /* address family must be the same */
101 if (rmt_sin->sa_family != our_sin->sa_family) {
102 STRN_CPY(dest, result, STRING_LENGTH);
105 switch (our_sin->sa_family) {
107 alen = sizeof(struct sockaddr_in);
110 alen = sizeof(struct sockaddr_in6);
113 STRN_CPY(dest, result, STRING_LENGTH);
119 * If we use a single, buffered, bidirectional stdio stream ("r+" or
120 * "w+" mode) we may read our own output. Such behaviour would make sense
121 * with resources that support random-access operations, but not with
122 * sockets. ANSI C suggests several functions which can be called when
123 * you want to change IO direction, fseek seems the most portable.
127 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
129 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
132 * Set up a timer so we won't get stuck while waiting for the server.
135 if (setjmp(timebuf) == 0) {
136 signal(SIGALRM, timeout);
137 alarm(rfc931_timeout);
140 * Bind the local and remote ends of the query socket to the same
141 * IP addresses as the connection under investigation. We go
142 * through all this trouble because the local or remote system
143 * might have more than one network address. The RFC931 etc.
144 * client sends only port numbers; the server takes the IP
145 * addresses from the query socket.
149 memcpy(&our_query_sin, our_sin, alen);
150 memcpy(&rmt_query_sin, rmt_sin, alen);
151 switch (our_sin->sa_family) {
153 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT);
154 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT);
157 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT);
158 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT);
162 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
164 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
167 our_query_sin = *our_sin;
168 our_query_sin.sin_port = htons(ANY_PORT);
169 rmt_query_sin = *rmt_sin;
170 rmt_query_sin.sin_port = htons(RFC931_PORT);
172 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
173 sizeof(our_query_sin)) >= 0 &&
174 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
175 sizeof(rmt_query_sin)) >= 0) {
179 * Send query to server. Neglect the risk that a 13-byte
180 * write would have to be fragmented by the local system and
181 * cause trouble with buggy System V stdio libraries.
184 fprintf(fp, "%u,%u\r\n",
186 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port),
187 ntohs(((struct sockaddr_in *)our_sin)->sin_port));
189 ntohs(rmt_sin->sin_port),
190 ntohs(our_sin->sin_port));
193 fseek(fp, 0, SEEK_SET);
196 * Read response from server. Use fgets()/sscanf() so we can
197 * work around System V stdio libraries that incorrectly
198 * assume EOF when a read from a socket returns less than
202 if (fgets(buffer, sizeof(buffer), fp) != 0
203 && ferror(fp) == 0 && feof(fp) == 0
204 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
205 &rmt_port, &our_port, user) == 3
207 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port
208 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) {
210 && ntohs(rmt_sin->sin_port) == rmt_port
211 && ntohs(our_sin->sin_port) == our_port) {
215 * Strip trailing carriage return. It is part of the
216 * protocol, not part of the data.
219 if ((cp = strchr(user, '\r')) != NULL)
228 STRN_CPY(dest, result, STRING_LENGTH);