/*      $NetBSD: rdate.c,v 1.22 2017/08/26 19:26:32 ginsbach 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.
 *
 * 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.
 */
#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: rdate.c,v 1.22 2017/08/26 19:26:32 ginsbach Exp $");
#endif /* lint */

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>

#include <netinet/in.h>

#include <err.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <util.h>

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

static  void    usage(void);

static void
usage(void)
{
        (void) fprintf(stderr, "usage: %s [-46aps] host\n", getprogname());
        (void) fprintf(stderr, "  -4: use IPv4 addresses only\n");
        (void) fprintf(stderr, "  -6: use IPv6 addresses only\n");
        (void) fprintf(stderr, "  -a: use adjtime instead of instant change\n");
        (void) fprintf(stderr, "  -p: just print, don't set\n");
        (void) fprintf(stderr, "  -s: just set, don't print\n");
}

int
main(int argc, char *argv[])
{
        int             pr = 0, silent = 0, s;
        int             slidetime = 0;
        int             adjustment;
        uint32_t        data;
        time_t          tim;
        char           *hname;
        const char     *emsg = NULL;
        struct addrinfo hints, *res, *res0;
        int             c;
        int             error;
        int             family = AF_UNSPEC;

        adjustment = 0;
        while ((c = getopt(argc, argv, "46aps")) != -1)
                switch (c) {
                case '4':
                        family = AF_INET;
                        break;

                case '6':
                        family  = AF_INET6;
                        break;

                case 'a':
                        slidetime++;
                        break;

                case 'p':
                        pr++;
                        break;

                case 's':
                        silent++;
                        break;

                default:
                        usage();
                        return 1;
                }

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

        memset(&hints, 0, sizeof (hints));
        hints.ai_family = family;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_flags = AI_CANONNAME;
        error = getaddrinfo(hname, "time", &hints, &res0);
        if (error)
                errx(1, "%s: %s", gai_strerror(error), hname);

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

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

        if (read(s, &data, sizeof(uint32_t)) != sizeof(uint32_t))
                err(1, "Could not read data");

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

        if (!pr) {
            struct timeval  tv;
            if (!slidetime) {
                    logwtmp("|", "date", "");
                    tv.tv_sec = tim;
                    tv.tv_usec = 0;
                    if (settimeofday(&tv, NULL) == -1)
                            err(1, "Could not set time of day");
                    logwtmp("{", "date", "");
            } 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) {
                (void) fputs(ctime(&tim), stdout);
                if (slidetime)
                    (void) fprintf(stdout, 
                                   "%s: adjust local clock by %d seconds\n",
                                   getprogname(), adjustment);
        }
        return 0;
}