/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1983, 1984, 1985, 1986, 1987, 1988, 1989 AT&T     */
/*        All Rights Reserved   */

/*
 * University Copyright- Copyright (c) 1982, 1986, 1988
 * The Regents of the University of California
 * All Rights Reserved
 *
 * University Acknowledgment- Portions of this document are derived from
 * software developed by the University of California, Berkeley, and its
 * contributors.
 */

/*
 *  rdate - get date from remote machine
 *
 *      sets time, obtaining value from host
 *      on the tcp/time socket.
 */

#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#include <strings.h>
#include <unistd.h>
#include <stdlib.h>
#include <netdb.h>
#include <stdio.h>

/*
 * The timeserver returns with time of day in seconds since
 * Jan 1, 1900. We must subtract 86400(365*70 + 17) to get time
 * since Jan 1, 1970, which is what get/settimeofday uses.
 */

#define TOFFSET ((unsigned int)86400*(365*70 + 17))

/*
 * Before setting the system time, the value returned by the
 * timeserver is checked for plausibility. If the returned date
 * is before the time this program was written it cannot be
 * correct.
 */

#define WRITTEN 440199955               /* 22:45:55 13/Dec/1983 */
#define SECONDS_TO_MS   1000

static void timeout(int);

int
main(int argc, char **argv)
{
        int s, i;
        uint32_t time;
        struct timeval timestruct;
        unsigned int connect_timeout;
        /* number of seconds to wait for something to happen. */
        unsigned int rdate_timeout = 30;        /* seconds */
        struct addrinfo hints;
        struct addrinfo *res;
        int rc;

        if (argc != 2) {
                (void) fputs("usage: rdate host\n", stderr);
                exit(EXIT_FAILURE);
        }

        (void) memset(&hints, 0, sizeof (hints));
        hints.ai_protocol = IPPROTO_TCP;
        res = NULL;

        /*
         * getaddrinfo() may take a long time, because it can involve
         * NIS, DNS, or LDAP lookups. Set an alarm timer. Note that this
         * may still fail, depending on how SIGALRM is handled by the
         * functions invoked by getaddrinfo().
         */

        (void) signal(SIGALRM, timeout);
        (void) alarm(rdate_timeout);

        /*
         * Note: memory not freed due to short lifetime of program.
         */

        rc = getaddrinfo(argv[1], "time", &hints, &res);
        (void) alarm(0);

        if (rc != 0) {
                (void) fprintf(stderr, "Host name %s not found: %s\n", argv[1],
                    gai_strerror(rc));
                exit(EXIT_FAILURE);
        }

        connect_timeout = rdate_timeout * SECONDS_TO_MS;
        for (; res != NULL; res = res->ai_next) {
                s = socket(res->ai_addr->sa_family, res->ai_socktype,
                    res->ai_protocol);
                if (s < 0) {
                        perror("rdate: socket");
                        exit(EXIT_FAILURE);
                }

                if (setsockopt(s, IPPROTO_TCP, TCP_CONN_ABORT_THRESHOLD,
                    (char *)&connect_timeout, sizeof (connect_timeout)) == -1) {
                        perror("setsockopt TCP_CONN_ABORT_THRESHOLD");
                }

                if (connect(s, res->ai_addr, res->ai_addrlen) >= 0)
                        break;

                if (res->ai_next == NULL) {
                        perror("rdate: connect");
                        (void) close(s);
                        exit(EXIT_FAILURE);
                }

                (void) close(s);
        }

        (void) alarm(rdate_timeout);
        if (read(s, (char *)&time, sizeof (time)) != sizeof (time)) {
                perror("rdate: read");
                exit(EXIT_FAILURE);
        }
        (void) alarm(0);

        time = ntohl(time) - TOFFSET;
        /* date must be later than when program was written */
        if (time < WRITTEN) {
                (void) fprintf(stderr, "didn't get plausible time from %s\n",
                    argv[1]);
                exit(EXIT_FAILURE);
        }
        timestruct.tv_usec = 0;
        timestruct.tv_sec = time;
        i = settimeofday(&timestruct, 0);
        if (i == -1) {
                perror("couldn't set time of day");
                exit(EXIT_FAILURE);
        } else {
                (void) printf("%s", ctime(&timestruct.tv_sec));
#if defined(i386)
                (void) system("/usr/sbin/rtc -c > /dev/null 2>&1");
#endif
        }
        return (EXIT_SUCCESS);
}

/*ARGSUSED*/
static void
timeout(int sig)
{
        (void) fputs("couldn't contact time server\n", stderr);
        exit(EXIT_FAILURE);
        /* NOTREACHED */
}