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(int sig) 70 { 71 longjmp(timebuf, sig); 72 } 73 74 /* rfc931 - return remote user name, given socket structures */ 75 76 void rfc931(rmt_sin, our_sin, dest) 77 #ifdef INET6 78 struct sockaddr *rmt_sin; 79 struct sockaddr *our_sin; 80 #else 81 struct sockaddr_in *rmt_sin; 82 struct sockaddr_in *our_sin; 83 #endif 84 char *dest; 85 { 86 unsigned rmt_port; 87 unsigned our_port; 88 #ifdef INET6 89 struct sockaddr_storage rmt_query_sin; 90 struct sockaddr_storage our_query_sin; 91 int alen; 92 #else 93 struct sockaddr_in rmt_query_sin; 94 struct sockaddr_in our_query_sin; 95 #endif 96 char user[256]; /* XXX */ 97 char buffer[512]; /* XXX */ 98 char *cp; 99 char *result = unknown; 100 FILE *fp; 101 102 #ifdef INET6 103 /* address family must be the same */ 104 if (rmt_sin->sa_family != our_sin->sa_family) { 105 STRN_CPY(dest, result, STRING_LENGTH); 106 return; 107 } 108 switch (our_sin->sa_family) { 109 case AF_INET: 110 alen = sizeof(struct sockaddr_in); 111 break; 112 case AF_INET6: 113 alen = sizeof(struct sockaddr_in6); 114 break; 115 default: 116 STRN_CPY(dest, result, STRING_LENGTH); 117 return; 118 } 119 #endif 120 121 /* 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. 127 */ 128 129 #ifdef INET6 130 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) { 131 #else 132 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) { 133 #endif 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 fseek(fp, 0, SEEK_SET); 197 198 /* 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 202 * requested. 203 */ 204 205 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) == 3 209 #ifdef INET6 210 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port 211 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) { 212 #else 213 && ntohs(rmt_sin->sin_port) == rmt_port 214 && ntohs(our_sin->sin_port) == our_port) { 215 #endif 216 217 /* 218 * Strip trailing carriage return. It is part of the 219 * protocol, not part of the data. 220 */ 221 222 if (cp = strchr(user, '\r')) 223 *cp = 0; 224 result = user; 225 } 226 } 227 alarm(0); 228 } 229 fclose(fp); 230 } 231 STRN_CPY(dest, result, STRING_LENGTH); 232 } 233