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: src/contrib/tcp_wrappers/rfc931.c,v 1.2.2.1 2000/07/18 16:41:11 dwmalone Exp $ 12 */ 13 14 /* System libraries. */ 15 16 #include <stdio.h> 17 #include <syslog.h> 18 #include <sys/types.h> 19 #include <sys/socket.h> 20 #include <netinet/in.h> 21 #include <setjmp.h> 22 #include <signal.h> 23 #include <string.h> 24 #include <unistd.h> 25 26 #ifndef SEEK_SET 27 #define SEEK_SET 0 28 #endif 29 30 /* Local stuff. */ 31 32 #include "tcpd.h" 33 34 #define RFC931_PORT 113 /* Semi-well-known port */ 35 #define ANY_PORT 0 /* Any old port will do */ 36 37 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */ 38 39 static jmp_buf timebuf; 40 41 /* fsocket - open stdio stream on top of socket */ 42 43 static FILE *fsocket(domain, type, protocol) 44 int domain; 45 int type; 46 int protocol; 47 { 48 int s; 49 FILE *fp; 50 51 if ((s = socket(domain, type, protocol)) < 0) { 52 tcpd_warn("socket: %m"); 53 return (0); 54 } else { 55 if ((fp = fdopen(s, "r+")) == 0) { 56 tcpd_warn("fdopen: %m"); 57 close(s); 58 } 59 return (fp); 60 } 61 } 62 63 /* timeout - handle timeouts */ 64 65 static void timeout(sig) 66 int sig; 67 { 68 longjmp(timebuf, sig); 69 } 70 71 /* rfc931 - return remote user name, given socket structures */ 72 73 void rfc931(rmt_sin, our_sin, dest) 74 #ifdef INET6 75 struct sockaddr *rmt_sin; 76 struct sockaddr *our_sin; 77 #else 78 struct sockaddr_in *rmt_sin; 79 struct sockaddr_in *our_sin; 80 #endif 81 char *dest; 82 { 83 unsigned rmt_port; 84 unsigned our_port; 85 #ifdef INET6 86 struct sockaddr_storage rmt_query_sin; 87 struct sockaddr_storage our_query_sin; 88 int alen; 89 #else 90 struct sockaddr_in rmt_query_sin; 91 struct sockaddr_in our_query_sin; 92 #endif 93 char user[256]; /* XXX */ 94 char buffer[512]; /* XXX */ 95 char *cp; 96 char *result = unknown; 97 FILE *fp; 98 99 #ifdef INET6 100 /* address family must be the same */ 101 if (rmt_sin->sa_family != our_sin->sa_family) { 102 STRN_CPY(dest, result, STRING_LENGTH); 103 return; 104 } 105 switch (our_sin->sa_family) { 106 case AF_INET: 107 alen = sizeof(struct sockaddr_in); 108 break; 109 case AF_INET6: 110 alen = sizeof(struct sockaddr_in6); 111 break; 112 default: 113 STRN_CPY(dest, result, STRING_LENGTH); 114 return; 115 } 116 #endif 117 118 /* 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. 124 */ 125 126 #ifdef INET6 127 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) { 128 #else 129 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) { 130 #endif 131 /* 132 * Set up a timer so we won't get stuck while waiting for the server. 133 */ 134 135 if (setjmp(timebuf) == 0) { 136 signal(SIGALRM, timeout); 137 alarm(rfc931_timeout); 138 139 /* 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. 146 */ 147 148 #ifdef INET6 149 memcpy(&our_query_sin, our_sin, alen); 150 memcpy(&rmt_query_sin, rmt_sin, alen); 151 switch (our_sin->sa_family) { 152 case AF_INET: 153 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT); 154 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT); 155 break; 156 case AF_INET6: 157 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT); 158 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT); 159 break; 160 } 161 162 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin, 163 alen) >= 0 && 164 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin, 165 alen) >= 0) { 166 #else 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); 171 172 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) { 176 #endif 177 178 /* 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. 182 */ 183 184 fprintf(fp, "%u,%u\r\n", 185 #ifdef INET6 186 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port), 187 ntohs(((struct sockaddr_in *)our_sin)->sin_port)); 188 #else 189 ntohs(rmt_sin->sin_port), 190 ntohs(our_sin->sin_port)); 191 #endif 192 fflush(fp); 193 fseek(fp, 0, SEEK_SET); 194 195 /* 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 199 * requested. 200 */ 201 202 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) == 3 206 #ifdef INET6 207 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port 208 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) { 209 #else 210 && ntohs(rmt_sin->sin_port) == rmt_port 211 && ntohs(our_sin->sin_port) == our_port) { 212 #endif 213 214 /* 215 * Strip trailing carriage return. It is part of the 216 * protocol, not part of the data. 217 */ 218 219 if ((cp = strchr(user, '\r')) != NULL) 220 *cp = 0; 221 result = user; 222 } 223 } 224 alarm(0); 225 } 226 fclose(fp); 227 } 228 STRN_CPY(dest, result, STRING_LENGTH); 229 } 230