1 /* 2 * Copyright 2004 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 #pragma ident "%Z%%M% %I% %E% SMI" 7 8 /* 9 * rfc931() speaks a common subset of the RFC 931, AUTH, TAP, IDENT and RFC 10 * 1413 protocols. It queries an RFC 931 etc. compatible daemon on a remote 11 * host to look up the owner of a connection. The information should not be 12 * used for authentication purposes. This routine intercepts alarm signals. 13 * 14 * Diagnostics are reported through syslog(3). 15 * 16 * Author: Wietse Venema, Eindhoven University of Technology, The Netherlands. 17 */ 18 19 #ifndef lint 20 static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34"; 21 #endif 22 23 /* System libraries. */ 24 25 #include <stdio.h> 26 #include <stdlib.h> 27 #include <unistd.h> 28 #include <syslog.h> 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <netinet/in.h> 32 #include <setjmp.h> 33 #include <signal.h> 34 #include <string.h> 35 36 /* Local stuff. */ 37 38 #include "tcpd.h" 39 40 #define RFC931_PORT 113 /* Semi-well-known port */ 41 #define ANY_PORT 0 /* Any old port will do */ 42 43 int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */ 44 45 static jmp_buf timebuf; 46 47 /* fsocket - open stdio stream on top of socket */ 48 49 static FILE *fsocket(domain, type, protocol) 50 int domain; 51 int type; 52 int protocol; 53 { 54 int s; 55 FILE *fp; 56 57 if ((s = socket(domain, type, protocol)) < 0) { 58 tcpd_warn("socket: %m"); 59 return (0); 60 } else { 61 if ((fp = fdopen(s, "r+")) == 0) { 62 tcpd_warn("fdopen: %m"); 63 close(s); 64 } 65 return (fp); 66 } 67 } 68 69 /* timeout - handle timeouts */ 70 71 static void timeout(sig) 72 int sig; 73 { 74 longjmp(timebuf, sig); 75 } 76 77 /* rfc931 - return remote user name, given socket structures */ 78 79 void rfc931(rmt_sin, our_sin, dest) 80 struct sockaddr_gen *rmt_sin; 81 struct sockaddr_gen *our_sin; 82 char *dest; 83 { 84 unsigned rmt_port; 85 unsigned our_port; 86 struct sockaddr_gen rmt_query_sin; 87 struct sockaddr_gen our_query_sin; 88 char user[256]; /* XXX */ 89 char buffer[512]; /* XXX */ 90 char *cp; 91 char *result = unknown; 92 FILE *fp; 93 unsigned saved_timeout = 0; 94 struct sigaction nact, oact; 95 96 /* 97 * Use one unbuffered stdio stream for writing to and for reading from 98 * the RFC931 etc. server. This is done because of a bug in the SunOS 99 * 4.1.x stdio library. The bug may live in other stdio implementations, 100 * too. When we use a single, buffered, bidirectional stdio stream ("r+" 101 * or "w+" mode) we read our own output. Such behaviour would make sense 102 * with resources that support random-access operations, but not with 103 * sockets. 104 */ 105 106 if ((fp = fsocket(SGFAM(rmt_sin), SOCK_STREAM, 0)) != 0) { 107 setbuf(fp, (char *) 0); 108 109 /* 110 * Set up a timer so we won't get stuck while waiting for the server. 111 */ 112 113 if (setjmp(timebuf) == 0) { 114 /* 115 * save the pending time in case the caller has armed an alarm. 116 */ 117 118 saved_timeout = alarm(0); 119 120 /* 121 * It's guaranteed to enter this 'if' condition on the direct 122 * invocation of setjmp and hence no additional checks while 123 * restoring the signal handler. 124 * Now, get the old handler and set the new one 125 */ 126 nact.sa_handler = timeout; 127 nact.sa_flags = 0; 128 (void) sigemptyset(&nact.sa_mask); 129 (void) sigaction(SIGALRM, &nact, &oact); 130 alarm(rfc931_timeout); 131 132 /* 133 * Bind the local and remote ends of the query socket to the same 134 * IP addresses as the connection under investigation. We go 135 * through all this trouble because the local or remote system 136 * might have more than one network address. The RFC931 etc. 137 * client sends only port numbers; the server takes the IP 138 * addresses from the query socket. 139 */ 140 141 our_query_sin = *our_sin; 142 SGPORT(&our_query_sin) = htons(ANY_PORT); 143 rmt_query_sin = *rmt_sin; 144 SGPORT(&rmt_query_sin) = htons(RFC931_PORT); 145 146 if (bind(fileno(fp), (struct sockaddr *) &our_query_sin, 147 SGSOCKADDRSZ(&our_query_sin)) >= 0 && 148 connect(fileno(fp), (struct sockaddr *) &rmt_query_sin, 149 SGSOCKADDRSZ(&rmt_query_sin)) >= 0) { 150 151 /* 152 * Send query to server. Neglect the risk that a 13-byte 153 * write would have to be fragmented by the local system and 154 * cause trouble with buggy System V stdio libraries. 155 */ 156 157 fprintf(fp, "%u,%u\r\n", 158 ntohs(SGPORT(rmt_sin)), 159 ntohs(SGPORT(our_sin))); 160 fflush(fp); 161 162 /* 163 * Read response from server. Use fgets()/sscanf() so we can 164 * work around System V stdio libraries that incorrectly 165 * assume EOF when a read from a socket returns less than 166 * requested. 167 */ 168 169 if (fgets(buffer, sizeof(buffer), fp) != 0 170 && ferror(fp) == 0 && feof(fp) == 0 171 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s", 172 &rmt_port, &our_port, user) == 3 173 && ntohs(SGPORT(rmt_sin)) == rmt_port 174 && ntohs(SGPORT(our_sin)) == our_port) { 175 176 /* 177 * Strip trailing carriage return. It is part of the 178 * protocol, not part of the data. 179 */ 180 181 if (cp = strchr(user, '\r')) 182 *cp = 0; 183 result = user; 184 } 185 } 186 alarm(0); 187 } 188 /* Restore the old handler */ 189 (void) sigaction(SIGALRM, &oact, NULL); 190 if (saved_timeout > 0) 191 alarm(saved_timeout); 192 fclose(fp); 193 } 194 STRN_CPY(dest, result, STRING_LENGTH); 195 } 196