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: stable/10/contrib/tcp_wrappers/rfc931.c 311814 2017-01-09 20:14:02Z dim $ 12 */ 13 14#ifndef lint 15static 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 41int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */ 42 43static jmp_buf timebuf; 44 45/* fsocket - open stdio stream on top of socket */ 46 47static FILE *fsocket(domain, type, protocol) 48int domain; 49int type; 50int 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 69static void timeout(sig) 70int sig; 71{ 72 longjmp(timebuf, sig); 73} 74 75/* rfc931 - return remote user name, given socket structures */ 76 77void rfc931(rmt_sin, our_sin, dest) 78#ifdef INET6 79struct sockaddr *rmt_sin; 80struct sockaddr *our_sin; 81#else 82struct sockaddr_in *rmt_sin; 83struct sockaddr_in *our_sin; 84#endif 85char *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