/*	$OpenBSD: rdate.c,v 1.8 1997/02/06 15:00:27 kstailey 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 $";
#else
static char rcsid[] = "$OpenBSD: rdate.c,v 1.8 1997/02/06 15:00:27 kstailey Exp $";
#endif
#endif				/* lint */

#include <sys/types.h>
#include <sys/param.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netdb.h>
#include <netinet/in.h>
#include <time.h>

/* seconds from midnight Jan 1900 - 1970 */
#if __STDC__
#define DIFFERENCE 2208988800UL
#else
#define DIFFERENCE 2208988800
#endif

extern char    *__progname;

static void
usage()
{
	(void) fprintf(stderr, "Usage: %s [-psa] host\n", __progname);
	(void) fprintf(stderr, "  -p: just print, don't set\n");
	(void) fprintf(stderr, "  -s: just set, don't print\n");
	(void) fprintf(stderr, "  -a: use adjtime instead of instant change\n");
}

int
main(argc, argv)
	int             argc;
	char           *argv[];
{
	int             pr = 0, silent = 0, s;
	int		slidetime = 0;
	int		adjustment;
	time_t          tim;
	char           *hname;
	struct hostent *hp;
	struct protoent *pp, ppp;
	struct servent *sp, ssp;
	struct sockaddr_in sa;
	extern int      optind;
	int             c;

	while ((c = getopt(argc, argv, "psa")) != -1)
		switch (c) {
		case 'p':
			pr++;
			break;

		case 's':
			silent++;
			break;

		case 'a':
			slidetime++;
			break;

		default:
			usage();
			return 1;
		}

	if (argc - 1 != optind) {
		usage();
		return 1;
	}
	hname = argv[optind];

	if ((hp = gethostbyname(hname)) == NULL) {
		warnx("%s: %s", hname, hstrerror(h_errno));
		return 1;
	}

	if ((sp = getservbyname("time", "tcp")) == NULL) {
		sp = &ssp;
		sp->s_port = 37;
		sp->s_proto = "tcp";
	}
	if ((pp = getprotobyname(sp->s_proto)) == NULL) {
		pp = &ppp;
		pp->p_proto = 6;
	}
	if ((s = socket(AF_INET, SOCK_STREAM, pp->p_proto)) == -1)
		err(1, "Could not create socket");

	bzero(&sa, sizeof sa);
	sa.sin_family = AF_INET;
	sa.sin_port = sp->s_port;

	(void) memcpy(&(sa.sin_addr.s_addr), hp->h_addr, hp->h_length);

	if (connect(s, (struct sockaddr *) & sa, sizeof(sa)) == -1)
		err(1, "Could not connect socket");

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

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

	if (!pr) {
	    struct timeval  tv;
	    if (!slidetime) {
		    tv.tv_sec = tim;
		    tv.tv_usec = 0;
		    if (settimeofday(&tv, NULL) == -1)
			    err(1, "Could not set time of day");
	    } else {
		    struct timeval tv_current;
		    if (gettimeofday(&tv_current, NULL) == -1)
			    err(1, "Could not get local time of day");
		    adjustment = tv.tv_sec = tim - tv_current.tv_sec;
		    tv.tv_usec = 0;
		    if (adjtime(&tv, NULL) == -1)
			    err(1, "Could not adjust time of day");
	    }
	}

	if (!silent) {
		struct tm      *ltm;
		char		buf[80];

		ltm = localtime(&tim);
		(void) strftime(buf, 80, "%a %b %e %H:%M:%S %Z %Y\n", ltm);
		(void) fputs(buf, stdout);

		if (slidetime)
		    (void) fprintf(stdout, 
				   "%s: adjust local clock by %d seconds\n",
				   __progname, adjustment);
	}
	return 0;
}