avoid null ptr deref, from glenn@sun

[unix-history] / usr / src / libexec / talkd / talkd.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.  The Berkeley software License Agreement
 * specifies the terms and conditions for redistribution.
 */

#ifndef lint
char copyright[] =
"@(#) Copyright (c) 1983 Regents of the University of California.\n\
 All rights reserved.\n";
#endif not lint

#ifndef lint
static char sccsid[] = "@(#)talkd.c	5.2 (Berkeley) %G%";
#endif not lint

/*
 * The top level of the daemon, the format is heavily borrowed
 * from rwhod.c. Basically: find out who and where you are; 
 * disconnect all descriptors and ttys, and then endless
 * loop on waiting for and processing requests
 */
#include <stdio.h>
#include <errno.h>
#include <signal.h>
#include <syslog.h>

#include <protocols/talkd.h>

CTL_MSG		request;
CTL_RESPONSE	response;

int	sockt;
int	debug = 0;
int	timeout();
long	lastmsgtime;

char	hostname[32];

#define TIMEOUT 30
#define MAXIDLE 120

main(argc, argv)
	int argc;
	char *argv[];
{
	register CTL_MSG *mp = &request;
	int cc;

	if (getuid()) {
		fprintf(stderr, "%s: getuid: not super-user", argv[0]);
		exit(1);
	}
	openlog("talkd", LOG_PID, LOG_DAEMON);
	if (gethostname(hostname, sizeof (hostname) - 1) < 0) {
		syslog(LOG_ERR, "gethostname: %m");
		_exit(1);
	}
	if (chdir("/dev") < 0) {
		syslog(LOG_ERR, "chdir: /dev: %m");
		_exit(1);
	}
	if (argc > 1 && strcmp(argv[1], "-d") == 0)
		debug = 1;
	signal(SIGALRM, timeout);
	alarm(TIMEOUT);
	for (;;) {
		extern int errno;

		cc = recv(0, (char *)mp, sizeof (*mp), 0);
		if (cc != sizeof (*mp)) {
			if (cc < 0 && errno != EINTR)
				syslog(LOG_WARNING, "recv: %m");
			continue;
		}
		lastmsgtime = time(0);
		process_request(mp, &response);
		/* can block here, is this what I want? */
		cc = sendto(sockt, (char *)&response,
		    sizeof (response), 0, &mp->ctl_addr, sizeof (mp->ctl_addr));
		if (cc != sizeof (response))
			syslog(LOG_WARNING, "sendto: %m");
	}
}

timeout()
{

	if (time(0) - lastmsgtime >= MAXIDLE)
		_exit(0);
	alarm(TIMEOUT);
}