166 lines
4.3 KiB
C
166 lines
4.3 KiB
C
/*
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* rfc931() speaks a common subset of the RFC 931, AUTH, TAP, IDENT and RFC
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* 1413 protocols. It queries an RFC 931 etc. compatible daemon on a remote
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* host to look up the owner of a connection. The information should not be
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* used for authentication purposes. This routine intercepts alarm signals.
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*
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* Diagnostics are reported through syslog(3).
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*
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* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
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*/
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#ifndef lint
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static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
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#endif
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/* System libraries. */
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#include <stdio.h>
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#include <syslog.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <setjmp.h>
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#include <signal.h>
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#include <string.h>
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/* Local stuff. */
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#include "tcpd.h"
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#define RFC931_PORT 113 /* Semi-well-known port */
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#define ANY_PORT 0 /* Any old port will do */
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int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */
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static jmp_buf timebuf;
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/* fsocket - open stdio stream on top of socket */
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static FILE *fsocket(domain, type, protocol)
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int domain;
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int type;
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int protocol;
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{
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int s;
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FILE *fp;
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if ((s = socket(domain, type, protocol)) < 0) {
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tcpd_warn("socket: %m");
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return (0);
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} else {
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if ((fp = fdopen(s, "r+")) == 0) {
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tcpd_warn("fdopen: %m");
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close(s);
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}
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return (fp);
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}
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}
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/* timeout - handle timeouts */
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static void timeout(sig)
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int sig;
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{
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longjmp(timebuf, sig);
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}
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/* rfc931 - return remote user name, given socket structures */
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void rfc931(rmt_sin, our_sin, dest)
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struct sockaddr_in *rmt_sin;
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struct sockaddr_in *our_sin;
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char *dest;
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{
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unsigned rmt_port;
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unsigned our_port;
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struct sockaddr_in rmt_query_sin;
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struct sockaddr_in our_query_sin;
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char user[256]; /* XXX */
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char buffer[512]; /* XXX */
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char *cp;
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char *result = unknown;
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FILE *fp;
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/*
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* Use one unbuffered stdio stream for writing to and for reading from
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* the RFC931 etc. server. This is done because of a bug in the SunOS
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* 4.1.x stdio library. The bug may live in other stdio implementations,
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* too. When we use a single, buffered, bidirectional stdio stream ("r+"
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* or "w+" mode) we read our own output. Such behaviour would make sense
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* with resources that support random-access operations, but not with
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* sockets.
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*/
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if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
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setbuf(fp, (char *) 0);
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/*
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* Set up a timer so we won't get stuck while waiting for the server.
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*/
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if (setjmp(timebuf) == 0) {
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signal(SIGALRM, timeout);
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alarm(rfc931_timeout);
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/*
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* Bind the local and remote ends of the query socket to the same
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* IP addresses as the connection under investigation. We go
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* through all this trouble because the local or remote system
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* might have more than one network address. The RFC931 etc.
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* client sends only port numbers; the server takes the IP
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* addresses from the query socket.
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*/
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our_query_sin = *our_sin;
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our_query_sin.sin_port = htons(ANY_PORT);
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rmt_query_sin = *rmt_sin;
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rmt_query_sin.sin_port = htons(RFC931_PORT);
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if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
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sizeof(our_query_sin)) >= 0 &&
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connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
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sizeof(rmt_query_sin)) >= 0) {
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/*
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* Send query to server. Neglect the risk that a 13-byte
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* write would have to be fragmented by the local system and
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* cause trouble with buggy System V stdio libraries.
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*/
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fprintf(fp, "%u,%u\r\n",
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ntohs(rmt_sin->sin_port),
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ntohs(our_sin->sin_port));
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fflush(fp);
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/*
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* Read response from server. Use fgets()/sscanf() so we can
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* work around System V stdio libraries that incorrectly
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* assume EOF when a read from a socket returns less than
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* requested.
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*/
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if (fgets(buffer, sizeof(buffer), fp) != 0
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&& ferror(fp) == 0 && feof(fp) == 0
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&& sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
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&rmt_port, &our_port, user) == 3
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&& ntohs(rmt_sin->sin_port) == rmt_port
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&& ntohs(our_sin->sin_port) == our_port) {
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/*
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* Strip trailing carriage return. It is part of the
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* protocol, not part of the data.
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*/
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if (cp = strchr(user, '\r'))
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*cp = 0;
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result = user;
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}
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}
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alarm(0);
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}
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fclose(fp);
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}
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STRN_CPY(dest, result, STRING_LENGTH);
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}
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