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 29 /* Local stuff. */ 30 31 #include "tcpd.h" 32 33 #define RFC931_PORT 113 /* Semi-well-known port */ 34 #define ANY_PORT 0 /* Any old port will do */ 35 36 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */ 37 38 static jmp_buf timebuf; 39 40 /* fsocket - open stdio stream on top of socket */ 41 42 static FILE *fsocket(domain, type, protocol) 43 int domain; 44 int type; 45 int protocol; 46 { 47 int s; 48 FILE *fp; 49 50 if ((s = socket(domain, type, protocol)) < 0) { 51 tcpd_warn("socket: %m"); 52 return (0); 53 } else { 54 if ((fp = fdopen(s, "r+")) == 0) { 55 tcpd_warn("fdopen: %m"); 56 close(s); 57 } 58 return (fp); 59 } 60 } 61 62 /* timeout - handle timeouts */ 63 64 static void timeout(sig) 65 int sig; 66 { 67 longjmp(timebuf, sig); 68 } 69 70 /* rfc931 - return remote user name, given socket structures */ 71 72 void rfc931(rmt_sin, our_sin, dest) 73 #ifdef INET6 74 struct sockaddr *rmt_sin; 75 struct sockaddr *our_sin; 76 #else 77 struct sockaddr_in *rmt_sin; 78 struct sockaddr_in *our_sin; 79 #endif 80 char *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 } 232