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/* $NetBSD: rfc931.c,v 1.10 2012/03/22 22:59:43 joerg Exp $ */
/*
* rfc931() speaks a common subset of the RFC 931, AUTH, TAP, IDENT and RFC
* 1413 protocols. It queries an RFC 931 etc. compatible daemon on a remote
* host to look up the owner of a connection. The information should not be
* used for authentication purposes. This routine intercepts alarm signals.
*
* Diagnostics are reported through syslog(3).
*
* Author: Wietse Venema, Eindhoven University of Technology, The Netherlands.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
#else
__RCSID("$NetBSD: rfc931.c,v 1.10 2012/03/22 22:59:43 joerg Exp $");
#endif
#endif
/* System libraries. */
#include <stdio.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <unistd.h>
#include <setjmp.h>
#include <signal.h>
#include <string.h>
/* Local stuff. */
#include "tcpd.h"
#define RFC931_PORT 113 /* Semi-well-known port */
#define ANY_PORT 0 /* Any old port will do */
int rfc931_timeout = RFC931_TIMEOUT;/* Global so it can be changed */
static jmp_buf timebuf;
static FILE *fsocket(int, int, int);
static void timeout(int) __dead;
/* fsocket - open stdio stream on top of socket */
static FILE *
fsocket(int domain, int type, int protocol)
{
int s;
FILE *fp;
if ((s = socket(domain, type, protocol)) < 0) {
tcpd_warn("socket: %m");
return (0);
} else {
if ((fp = fdopen(s, "r+")) == 0) {
tcpd_warn("fdopen: %m");
close(s);
}
return (fp);
}
}
/* timeout - handle timeouts */
static void
timeout(int sig)
{
longjmp(timebuf, sig);
}
/* rfc931 - return remote user name, given socket structures */
void
rfc931(struct sockaddr *rmt_sin, struct sockaddr *our_sin, char *dest)
{
unsigned rmt_port;
unsigned our_port;
struct sockaddr_storage rmt_query_sin;
struct sockaddr_storage our_query_sin;
char user[256]; /* XXX */
char buffer[512]; /* XXX */
char *cp;
char *result = unknown;
FILE *fp;
volatile int salen;
u_short * volatile rmt_portp;
u_short * volatile our_portp;
/* address family must be the same */
if (rmt_sin->sa_family != our_sin->sa_family) {
strlcpy(dest, result, STRING_LENGTH);
return;
}
switch (rmt_sin->sa_family) {
case AF_INET:
salen = sizeof(struct sockaddr_in);
rmt_portp = &(((struct sockaddr_in *)rmt_sin)->sin_port);
break;
#ifdef INET6
case AF_INET6:
salen = sizeof(struct sockaddr_in6);
rmt_portp = &(((struct sockaddr_in6 *)rmt_sin)->sin6_port);
break;
#endif
default:
strlcpy(dest, result, STRING_LENGTH);
return;
}
switch (our_sin->sa_family) {
case AF_INET:
our_portp = &(((struct sockaddr_in *)our_sin)->sin_port);
break;
#ifdef INET6
case AF_INET6:
our_portp = &(((struct sockaddr_in6 *)our_sin)->sin6_port);
break;
#endif
default:
strlcpy(dest, result, STRING_LENGTH);
return;
}
#ifdef __GNUC__
(void)&result; /* Avoid longjmp clobbering */
(void)&fp; /* XXX gcc */
#endif
/*
* Use one unbuffered stdio stream for writing to and for reading from
* the RFC931 etc. server. This is done because of a bug in the SunOS
* 4.1.x stdio library. The bug may live in other stdio implementations,
* too. When we use a single, buffered, bidirectional stdio stream ("r+"
* or "w+" mode) we read our own output. Such behaviour would make sense
* with resources that support random-access operations, but not with
* sockets.
*/
if ((fp = fsocket(rmt_sin->sa_family, SOCK_STREAM, 0)) != 0) {
setbuf(fp, (char *) 0);
/*
* Set up a timer so we won't get stuck while waiting for the server.
*/
if (setjmp(timebuf) == 0) {
signal(SIGALRM, timeout);
alarm(rfc931_timeout);
/*
* Bind the local and remote ends of the query socket to the same
* IP addresses as the connection under investigation. We go
* through all this trouble because the local or remote system
* might have more than one network address. The RFC931 etc.
* client sends only port numbers; the server takes the IP
* addresses from the query socket.
*/
memcpy(&our_query_sin, our_sin, salen);
switch (our_query_sin.ss_family) {
case AF_INET:
((struct sockaddr_in *)&our_query_sin)->sin_port =
htons(ANY_PORT);
break;
#ifdef INET6
case AF_INET6:
((struct sockaddr_in6 *)&our_query_sin)->sin6_port =
htons(ANY_PORT);
break;
#endif
}
memcpy(&rmt_query_sin, rmt_sin, salen);
switch (rmt_query_sin.ss_family) {
case AF_INET:
((struct sockaddr_in *)&rmt_query_sin)->sin_port =
htons(RFC931_PORT);
break;
#ifdef INET6
case AF_INET6:
((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port =
htons(RFC931_PORT);
break;
#endif
}
if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
salen) >= 0 &&
connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
salen) >= 0) {
/*
* Send query to server. Neglect the risk that a 13-byte
* write would have to be fragmented by the local system and
* cause trouble with buggy System V stdio libraries.
*/
fprintf(fp, "%u,%u\r\n",
ntohs(*rmt_portp),
ntohs(*our_portp));
fflush(fp);
/*
* Read response from server. Use fgets()/sscanf() so we can
* work around System V stdio libraries that incorrectly
* assume EOF when a read from a socket returns less than
* requested.
*/
if (fgets(buffer, sizeof(buffer), fp) != 0
&& ferror(fp) == 0 && feof(fp) == 0
&& sscanf(buffer, "%u , %u : USERID :%*[^:]:%255s",
&rmt_port, &our_port, user) == 3
&& ntohs(*rmt_portp) == rmt_port
&& ntohs(*our_portp) == our_port) {
/*
* Strip trailing carriage return. It is part of the
* protocol, not part of the data.
*/
if ((cp = strchr(user, '\r')) != NULL)
*cp = '\0';
result = user;
}
}
alarm(0);
}
fclose(fp);
}
strlcpy(dest, result, STRING_LENGTH);
}
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