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 fsocket(int domain,int type,int protocol)47 static FILE *fsocket(int domain, int type, int protocol) 48 { 49 int s; 50 FILE *fp; 51 52 if ((s = socket(domain, type, protocol)) < 0) { 53 tcpd_warn("socket: %m"); 54 return (0); 55 } else { 56 if ((fp = fdopen(s, "r+")) == 0) { 57 tcpd_warn("fdopen: %m"); 58 close(s); 59 } 60 return (fp); 61 } 62 } 63 64 /* timeout - handle timeouts */ 65 timeout(int sig)66 static void timeout(int sig) 67 { 68 longjmp(timebuf, sig); 69 } 70 71 /* rfc931 - return remote user name, given socket structures */ 72 73 #ifdef INET6 rfc931(struct sockaddr * rmt_sin,struct sockaddr * our_sin,char * dest)74 void rfc931(struct sockaddr *rmt_sin, struct sockaddr *our_sin, char *dest) 75 #else 76 void rfc931(struct sockaddr_in *rmt_sin, struct sockaddr_in *our_sin, 77 char *dest) 78 #endif 79 { 80 unsigned rmt_port; 81 unsigned our_port; 82 #ifdef INET6 83 struct sockaddr_storage rmt_query_sin; 84 struct sockaddr_storage our_query_sin; 85 int alen; 86 #else 87 struct sockaddr_in rmt_query_sin; 88 struct sockaddr_in our_query_sin; 89 #endif 90 char user[256]; /* XXX */ 91 char buffer[512]; /* XXX */ 92 char *cp; 93 char *result = unknown; 94 FILE *fp; 95 96 #ifdef INET6 97 /* address family must be the same */ 98 if (rmt_sin->sa_family != our_sin->sa_family) { 99 STRN_CPY(dest, result, STRING_LENGTH); 100 return; 101 } 102 switch (our_sin->sa_family) { 103 case AF_INET: 104 alen = sizeof(struct sockaddr_in); 105 break; 106 case AF_INET6: 107 alen = sizeof(struct sockaddr_in6); 108 break; 109 default: 110 STRN_CPY(dest, result, STRING_LENGTH); 111 return; 112 } 113 #endif 114 115 /* 116 * If we use a single, buffered, bidirectional stdio stream ("r+" or 117 * "w+" mode) we may read our own output. Such behaviour would make sense 118 * with resources that support random-access operations, but not with 119 * sockets. ANSI C suggests several functions which can be called when 120 * you want to change IO direction, fseek seems the most portable. 121 */ 122 123 #ifdef INET6 124 if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) { 125 #else 126 if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) { 127 #endif 128 /* 129 * Set up a timer so we won't get stuck while waiting for the server. 130 */ 131 132 if (setjmp(timebuf) == 0) { 133 signal(SIGALRM, timeout); 134 alarm(rfc931_timeout); 135 136 /* 137 * Bind the local and remote ends of the query socket to the same 138 * IP addresses as the connection under investigation. We go 139 * through all this trouble because the local or remote system 140 * might have more than one network address. The RFC931 etc. 141 * client sends only port numbers; the server takes the IP 142 * addresses from the query socket. 143 */ 144 145 #ifdef INET6 146 memcpy(&our_query_sin, our_sin, alen); 147 memcpy(&rmt_query_sin, rmt_sin, alen); 148 switch (our_sin->sa_family) { 149 case AF_INET: 150 ((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT); 151 ((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT); 152 break; 153 case AF_INET6: 154 ((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT); 155 ((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT); 156 break; 157 } 158 159 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin, 160 alen) >= 0 && 161 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin, 162 alen) >= 0) { 163 #else 164 our_query_sin = *our_sin; 165 our_query_sin.sin_port = htons(ANY_PORT); 166 rmt_query_sin = *rmt_sin; 167 rmt_query_sin.sin_port = htons(RFC931_PORT); 168 169 if (bind(fileno(fp), (struct sockaddr *) & our_query_sin, 170 sizeof(our_query_sin)) >= 0 && 171 connect(fileno(fp), (struct sockaddr *) & rmt_query_sin, 172 sizeof(rmt_query_sin)) >= 0) { 173 #endif 174 175 /* 176 * Send query to server. Neglect the risk that a 13-byte 177 * write would have to be fragmented by the local system and 178 * cause trouble with buggy System V stdio libraries. 179 */ 180 181 fprintf(fp, "%u,%u\r\n", 182 #ifdef INET6 183 ntohs(((struct sockaddr_in *)rmt_sin)->sin_port), 184 ntohs(((struct sockaddr_in *)our_sin)->sin_port)); 185 #else 186 ntohs(rmt_sin->sin_port), 187 ntohs(our_sin->sin_port)); 188 #endif 189 fflush(fp); 190 fseek(fp, 0, SEEK_SET); 191 192 /* 193 * Read response from server. Use fgets()/sscanf() so we can 194 * work around System V stdio libraries that incorrectly 195 * assume EOF when a read from a socket returns less than 196 * requested. 197 */ 198 199 if (fgets(buffer, sizeof(buffer), fp) != 0 200 && ferror(fp) == 0 && feof(fp) == 0 201 && sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s", 202 &rmt_port, &our_port, user) == 3 203 #ifdef INET6 204 && ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port 205 && ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) { 206 #else 207 && ntohs(rmt_sin->sin_port) == rmt_port 208 && ntohs(our_sin->sin_port) == our_port) { 209 #endif 210 211 /* 212 * Strip trailing carriage return. It is part of the 213 * protocol, not part of the data. 214 */ 215 216 if (cp = strchr(user, '\r')) 217 *cp = 0; 218 result = user; 219 } 220 } 221 alarm(0); 222 } 223 fclose(fp); 224 } 225 STRN_CPY(dest, result, STRING_LENGTH); 226 } 227