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/*
* 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.
*/
#ifndef lint
static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
#endif
/* System libraries. */
#include <stdio.h>
#include <unistd.h>
#include <syslog.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.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 sigjmp_buf timebuf;
/* fsocket - open stdio stream on top of socket */
static FILE *fsocket(domain, type, protocol)
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(sig)
int sig;
{
siglongjmp(timebuf, sig);
}
/* rfc931 - return remote user name, given socket structures */
void rfc931(rmt_sin, our_sin, dest)
#ifdef INET6
struct sockaddr *rmt_sin;
struct sockaddr *our_sin;
#else
struct sockaddr_in *rmt_sin;
struct sockaddr_in *our_sin;
#endif
char *dest;
{
unsigned rmt_port;
unsigned our_port;
#ifdef INET6
struct sockaddr_storage rmt_query_sin;
struct sockaddr_storage our_query_sin;
int alen;
#else
struct sockaddr_in rmt_query_sin;
struct sockaddr_in our_query_sin;
#endif
char user[256]; /* XXX */
char buffer[512]; /* XXX */
char *cp;
char *result = unknown;
FILE *fp;
unsigned saved_timeout;
struct sigaction nact, oact;
#ifdef INET6
/* address family must be the same */
if (rmt_sin->sa_family != our_sin->sa_family) {
STRN_CPY(dest, result, STRING_LENGTH);
return;
}
switch (our_sin->sa_family) {
case AF_INET:
alen = sizeof(struct sockaddr_in);
break;
case AF_INET6:
alen = sizeof(struct sockaddr_in6);
break;
default:
STRN_CPY(dest, result, STRING_LENGTH);
return;
}
#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.
*/
#ifdef INET6
if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
#else
if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
#endif
setbuf(fp, (char *) 0);
/*
* Set up a timer so we won't get stuck while waiting for the server.
*/
if (sigsetjmp(timebuf, 1) == 0) {
/* Save SIGALRM timer and handler. Sudheer Abdul-Salam, SUN. */
saved_timeout = alarm(0);
nact.sa_handler = timeout;
nact.sa_flags = 0;
(void) sigemptyset(&nact.sa_mask);
(void) sigaction(SIGALRM, &nact, &oact);
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.
*/
#ifdef INET6
memcpy(&our_query_sin, our_sin, alen);
memcpy(&rmt_query_sin, rmt_sin, alen);
switch (our_sin->sa_family) {
case AF_INET:
((struct sockaddr_in *)&our_query_sin)->sin_port = htons(ANY_PORT);
((struct sockaddr_in *)&rmt_query_sin)->sin_port = htons(RFC931_PORT);
break;
case AF_INET6:
((struct sockaddr_in6 *)&our_query_sin)->sin6_port = htons(ANY_PORT);
((struct sockaddr_in6 *)&rmt_query_sin)->sin6_port = htons(RFC931_PORT);
break;
}
if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
alen) >= 0 &&
connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
alen) >= 0) {
#else
our_query_sin = *our_sin;
our_query_sin.sin_port = htons(ANY_PORT);
rmt_query_sin = *rmt_sin;
rmt_query_sin.sin_port = htons(RFC931_PORT);
if (bind(fileno(fp), (struct sockaddr *) & our_query_sin,
sizeof(our_query_sin)) >= 0 &&
connect(fileno(fp), (struct sockaddr *) & rmt_query_sin,
sizeof(rmt_query_sin)) >= 0) {
#endif
/*
* 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",
#ifdef INET6
ntohs(((struct sockaddr_in *)rmt_sin)->sin_port),
ntohs(((struct sockaddr_in *)our_sin)->sin_port));
#else
ntohs(rmt_sin->sin_port),
ntohs(our_sin->sin_port));
#endif
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
#ifdef INET6
&& ntohs(((struct sockaddr_in *)rmt_sin)->sin_port) == rmt_port
&& ntohs(((struct sockaddr_in *)our_sin)->sin_port) == our_port) {
#else
&& ntohs(rmt_sin->sin_port) == rmt_port
&& ntohs(our_sin->sin_port) == our_port) {
#endif
/*
* Strip trailing carriage return. It is part of the
* protocol, not part of the data.
*/
if (cp = strchr(user, '\r'))
*cp = 0;
result = user;
}
}
alarm(0);
}
/* Restore SIGALRM timer and handler. Sudheer Abdul-Salam, SUN. */
(void) sigaction(SIGALRM, &oact, NULL);
if (saved_timeout > 0)
alarm(saved_timeout);
fclose(fp);
}
STRN_CPY(dest, result, STRING_LENGTH);
}
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