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 * $FreeBSD$ 12 */ 13 14 #ifndef lint 15 static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34"; 16 #endif 17 18 /* System libraries. */ 19 20 #include <stdio.h> 21 #include <syslog.h> 22 #include <sys/types.h> 23 #include <sys/socket.h> 24 #include <netinet/in.h> 25 #include <setjmp.h> 26 #include <signal.h> 27 #include <string.h> 28 #include <unistd.h> 29 30 #ifndef SEEK_SET 31 #define SEEK_SET 0 32 #endif 33 34 /* Local stuff. */ 35 36 #include "tcpd.h" 37 38 #define RFC931_PORT 113 /* Semi-well-known port */ 39 #define ANY_PORT 0 /* Any old port will do */ 40 41 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */ 42 43 static jmp_buf timebuf; 44 45 /* fsocket - open stdio stream on top of socket */ 46 47 static FILE *fsocket(domain, type, protocol) 48 int domain; 49 int type; 50 int protocol; 51 { 52 int s; 53 FILE *fp; 54 55 if ((s = socket(domain, type, protocol)) < 0) { 56 tcpd_warn("socket: %m"); 57 return (0); 58 } else { 59 if ((fp = fdopen(s, "r+")) == 0) { 60 tcpd_warn("fdopen: %m"); 61 close(s); 62 } 63 return (fp); 64 } 65 } 66 67 /* timeout - handle timeouts */ 68 69 static void timeout(sig) 70 int sig; 71 { 72 longjmp(timebuf, sig); 73 } 74 75 /* rfc931 - return remote user name, given socket structures */ 76 77 void rfc931(rmt_sin, our_sin, dest) 78 #ifdef INET6 79 struct sockaddr *rmt_sin; 80 struct sockaddr *our_sin; 81 #else 82 struct sockaddr_in *rmt_sin; 83 struct sockaddr_in *our_sin; 84 #endif 85 char *dest; 86 { 87 unsigned rmt_port; 88 unsigned our_port; 89 #ifdef INET6 90 struct sockaddr_storage rmt_query_sin; 91 struct sockaddr_storage our_query_sin; 92 int alen; 93 #else 94 struct sockaddr_in rmt_query_sin; 95 struct sockaddr_in our_query_sin; 96 #endif 97 char user[256]; /* XXX */ 98 char buffer[512]; /* XXX */ 99 char *cp; 100 char *result = unknown; 101 FILE *fp; 102 103 #ifdef INET6 104 /* address family must be the same */ 105 if (rmt_sin->sa_family != our_sin->sa_family) { 106 STRN_CPY(dest, result, STRING_LENGTH); 107 return; 108 } 109 switch (our_sin->sa_family) { 110 case AF_INET: 111 alen = sizeof(struct sockaddr_in); 112 break; 113 case AF_INET6: 114 alen = sizeof(struct sockaddr_in6); 115 break; 116 default: 117 STRN_CPY(dest, result, STRING_LENGTH); 118 return; 119 } 120 #endif 121 122 /* 123 * If we use a single, buffered, bidirectional stdio stream ("r+" or 124 * "w+" mode) we may read our own output. Such behaviour would make sense 125 * with resources that support random-access operations, but not with 126 * sockets. ANSI C suggests several functions which can be called when 127 * you want to change IO direction, fseek seems the most portable. 128 */ 129 130 #ifdef INET6 131 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) { 132 #else 133 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) { 134 #endif 135 /* 136 * Set up a timer so we won't get stuck while waiting for the server. 137 */ 138 139 if (setjmp(timebuf) == 0) { 140 signal(SIGALRM, timeout); 141 alarm(rfc931_timeout); 142 143 /* 144 * Bind the local and remote ends of the query socket to the same 145 * IP addresses as the connection under investigation. We go 146 * through all this trouble because the local or remote system 147 * might have more than one network address. The RFC931 etc. 148 * client sends only port numbers; the server takes the IP 149 * addresses from the query socket. 150 */ 151 152 #ifdef INET6 153 memcpy(&our_query_sin, our_sin, alen); 154 memcpy(&rmt_query_sin, rmt_sin, alen); 155 switch (our_sin->sa_family) { 156 case AF_INET: 157 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT); 158 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT); 159 break; 160 case AF_INET6: 161 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT); 162 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT); 163 break; 164 } 165 166 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin, 167 alen) >= 0 && 168 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin, 169 alen) >= 0) { 170 #else 171 our_query_sin = *our_sin; 172 our_query_sin.sin_port = htons(ANY_PORT); 173 rmt_query_sin = *rmt_sin; 174 rmt_query_sin.sin_port = htons(RFC931_PORT); 175 176 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin, 177 sizeof(our_query_sin)) >= 0 && 178 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin, 179 sizeof(rmt_query_sin)) >= 0) { 180 #endif 181 182 /* 183 * Send query to server. Neglect the risk that a 13-byte 184 * write would have to be fragmented by the local system and 185 * cause trouble with buggy System V stdio libraries. 186 */ 187 188 fprintf(fp, "%u,%u\r\n", 189 #ifdef INET6 190 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port), 191 ntohs(((struct sockaddr_in *)our_sin)->sin_port)); 192 #else 193 ntohs(rmt_sin->sin_port), 194 ntohs(our_sin->sin_port)); 195 #endif 196 fflush(fp); 197 fseek(fp, 0, SEEK_SET); 198 199 /* 200 * Read response from server. Use fgets()/sscanf() so we can 201 * work around System V stdio libraries that incorrectly 202 * assume EOF when a read from a socket returns less than 203 * requested. 204 */ 205 206 if (fgets(buffer, sizeof(buffer), fp) != 0 207 && ferror(fp) == 0 && feof(fp) == 0 208 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s", 209 &rmt_port, &our_port, user) == 3 210 #ifdef INET6 211 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port 212 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) { 213 #else 214 && ntohs(rmt_sin->sin_port) == rmt_port 215 && ntohs(our_sin->sin_port) == our_port) { 216 #endif 217 218 /* 219 * Strip trailing carriage return. It is part of the 220 * protocol, not part of the data. 221 */ 222 223 if (cp = strchr(user, '\r')) 224 *cp = 0; 225 result = user; 226 } 227 } 228 alarm(0); 229 } 230 fclose(fp); 231 } 232 STRN_CPY(dest, result, STRING_LENGTH); 233 } 234