/*	$OpenBSD: rfc868time.c,v 1.4 2002/08/10 21:37:28 jakob Exp $	*/
/*	$NetBSD: rdate.c,v 1.4 1996/03/16 12:37:45 pk Exp $	*/

/*
 * Copyright (c) 1994 Christos Zoulas
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Christos Zoulas.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * rdate.c: Set the date from the specified host
 *
 *	Uses the rfc868 time protocol at socket 37.
 *	Time is returned as the number of seconds since
 *	midnight January 1st 1900.
 */
#ifndef lint
#if 0
from: static char rcsid[] = "$NetBSD: rdate.c,v 1.3 1996/02/22 06:59:18 thorpej Exp $";
#else
static const char rcsid[] = "$OpenBSD: rfc868time.c,v 1.4 2002/08/10 21:37:28 jakob Exp $";
#endif
#endif				/* lint */

#include <sys/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>

#include <stdio.h>
#include <ctype.h>
#include <err.h>
#include <string.h>
#include <netdb.h>
#include <unistd.h>
#include <time.h>

/* seconds from midnight Jan 1900 - 1970 */
#define DIFFERENCE 2208988800UL


void
rfc868time_client (const char *hostname,
	     struct timeval *new, struct timeval *adjust)
{
	struct addrinfo hints, *res0, *res;
	struct timeval old;
	time_t tim;
	int s;
	int error;

	memset(&hints, 0, sizeof(hints));
	hints.ai_family = PF_UNSPEC;
	hints.ai_socktype = SOCK_STREAM;
	error = getaddrinfo(hostname, "time", &hints, &res0);
	if (error) {
		errx(1, "%s: %s", hostname, gai_strerror(error));
		/*NOTREACHED*/
	}

	s = -1;
	for (res = res0; res; res = res->ai_next) {
		s = socket(res->ai_family, res->ai_socktype, res->ai_protocol);
		if (s < 0)
			continue;

		if (connect(s, res->ai_addr, res->ai_addrlen) < 0) {
			close(s);
			s = -1;
			continue;
		}

		break;
	}
	if (s < 0)
		err(1, "Could not connect socket");
	freeaddrinfo(res0);

	if (read(s, &tim, sizeof(time_t)) != sizeof(time_t))
		err(1, "Could not read data");

	(void) close(s);
	tim = ntohl(tim) - DIFFERENCE;

	if (gettimeofday(&old, NULL) == -1)
		err(1, "Could not get local time of day");

	adjust->tv_sec = tim - old.tv_sec;
	adjust->tv_usec = 0;

	new->tv_sec = tim;
	new->tv_usec = 0;
}