1 /*
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.
6 *
7 * Diagnostics are reported through syslog(3).
8 *
9 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
10 *
11 * $FreeBSD: head/contrib/tcp_wrappers/rfc931.c 56977 2000-02-03 10:27:03Z shin $
12 */
13
14#ifndef lint
15static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
16#endif
17
18/* System libraries. */
19

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65int sig;
66{
67 longjmp(timebuf, sig);
68}
69
70/* rfc931 - return remote user name, given socket structures */
71
72void rfc931(rmt_sin, our_sin, dest)
73#ifdef INET6
74struct sockaddr *rmt_sin;
75struct sockaddr *our_sin;
76#else
77struct sockaddr_in *rmt_sin;
78struct sockaddr_in *our_sin;
79#endif
80char *dest;
81{
82 unsigned rmt_port;
83 unsigned our_port;
84#ifdef INET6
85 struct sockaddr_storage rmt_query_sin;
86 struct sockaddr_storage our_query_sin;
87 int alen;
88#else
89 struct sockaddr_in rmt_query_sin;
90 struct sockaddr_in our_query_sin;
91#endif
92 char user[256]; /* XXX */
93 char buffer[512]; /* XXX */
94 char *cp;
95 char *result = unknown;
96 FILE *fp;
97
98#ifdef INET6
99 /* address family must be the same */
100 if (rmt_sin->sa_family != our_sin->sa_family) {
101 STRN_CPY(dest, result, STRING_LENGTH);
102 return;
103 }
104 switch (our_sin->sa_family) {
105 case AF_INET:
106 alen = sizeof(struct sockaddr_in);
107 break;
108 case AF_INET6:
109 alen = sizeof(struct sockaddr_in6);
110 break;
111 default:
112 STRN_CPY(dest, result, STRING_LENGTH);
113 return;
114 }
115#endif
116
117 /*
118 * Use one unbuffered stdio stream for writing to and for reading from
119 * the RFC931 etc. server. This is done because of a bug in the SunOS
120 * 4.1.x stdio library. The bug may live in other stdio implementations,
121 * too. When we use a single, buffered, bidirectional stdio stream ("r+"
122 * or "w+" mode) we read our own output. Such behaviour would make sense
123 * with resources that support random-access operations, but not with
124 * sockets.
125 */
126
127#ifdef INET6
128 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
129#else
130 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
131#endif
132 setbuf(fp, (char *) 0);
133
134 /*
135 * Set up a timer so we won't get stuck while waiting for the server.
136 */
137
138 if (setjmp(timebuf) == 0) {
139 signal(SIGALRM, timeout);
140 alarm(rfc931_timeout);
141
142 /*
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.
149 */
150
151#ifdef INET6
152 memcpy(&our_query_sin, our_sin, alen);
153 memcpy(&rmt_query_sin, rmt_sin, alen);
154 switch (our_sin->sa_family) {
155 case AF_INET:
156 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT);
157 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT);
158 break;
159 case AF_INET6:
160 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT);
161 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT);
162 break;
163 }
164
165 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
166 alen) >= 0 &&
167 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
168 alen) >= 0) {
169#else
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);
174
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) {
179#endif
180
181 /*
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.
185 */
186
187 fprintf(fp, "%u,%u\r\n",
188#ifdef INET6
189 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port),
190 ntohs(((struct sockaddr_in *)our_sin)->sin_port));
191#else
192 ntohs(rmt_sin->sin_port),
193 ntohs(our_sin->sin_port));
194#endif
195 fflush(fp);
196
197 /*
198 * Read response from server. Use fgets()/sscanf() so we can
199 * work around System V stdio libraries that incorrectly
200 * assume EOF when a read from a socket returns less than
201 * requested.
202 */
203
204 if (fgets(buffer, sizeof(buffer), fp) != 0
205 && ferror(fp) == 0 && feof(fp) == 0
206 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
207 &rmt_port, &our_port, user) == 3
208#ifdef INET6
209 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port
210 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) {
211#else
212 && ntohs(rmt_sin->sin_port) == rmt_port
213 && ntohs(our_sin->sin_port) == our_port) {
214#endif
215
216 /*
217 * Strip trailing carriage return. It is part of the
218 * protocol, not part of the data.
219 */
220
221 if (cp = strchr(user, '\r'))
222 *cp = 0;
223 result = user;
224 }
225 }
226 alarm(0);
227 }
228 fclose(fp);
229 }
230 STRN_CPY(dest, result, STRING_LENGTH);
231}