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freebsd/contrib/tcp_wrappers/rfc931.c
David Malone c268f6e47c Stop the tcp_wrappers ident code sending a request which is split
across several packets. This is done by not turning off buffering
on the stdio stream for the ident connection. Originally this was
done to avoid reading back what you'd just written into the buffer.
However ANSI C gives a list of functions which should allow you to
safely change direction on a stdio stream, and Wietse found that
fseek seemed to be the most portable.

The original patch used a different workaround, but this should be
a real fix.

PR:		16086
Reviewed by:	wietse@porcupine.org
(Original version) Approved by:	markm
2000-07-14 15:07:37 +00:00

233 lines
5.9 KiB
C

/*
* 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.
*
* $FreeBSD$
*/
#ifndef lint
static char sccsid[] = "@(#) rfc931.c 1.10 95/01/02 16:11:34";
#endif
/* System libraries. */
#include <stdio.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>
#ifndef SEEK_SET
#define SEEK_SET 0
#endif
/* 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;
/* 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;
{
longjmp(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;
#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
/*
* If we use a single, buffered, bidirectional stdio stream ("r+" or
* "w+" mode) we may read our own output. Such behaviour would make sense
* with resources that support random-access operations, but not with
* sockets. ANSI C suggests several functions which can be called when
* you want to change IO direction, fseek seems the most portable.
*/
#ifdef INET6
if ((fp = fsocket(our_sin->sa_family, SOCK_STREAM, 0)) != 0) {
#else
if ((fp = fsocket(AF_INET, SOCK_STREAM, 0)) != 0) {
#endif
/*
* 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.
*/
#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);
fseek(fp, 0, SEEK_SET);
/*
* 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);
}
fclose(fp);
}
STRN_CPY(dest, result, STRING_LENGTH);
}