source: trunk/athena/etc/gettime/gettime.c @ 942

/*
 *      $Source: /afs/dev.mit.edu/source/repository/athena/etc/gettime/gettime.c,v $
 *      $Author: tytso $
 *      $Locker:  $
 *      $Header: /afs/dev.mit.edu/source/repository/athena/etc/gettime/gettime.c,v 1.4 1987-12-14 18:03:02 tytso Exp $
 */

#ifndef lint
static char *rcsid_gettime_c = "$Header: /afs/dev.mit.edu/source/repository/athena/etc/gettime/gettime.c,v 1.4 1987-12-14 18:03:02 tytso Exp $";
#endif  lint

#include <sys/types.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
#include <errno.h>
#include <netdb.h>
#include <signal.h>
#include <setjmp.h>

#define DEFAULT_TIME_SERVER "dcn1.arpa"

/* On the RT, we need to explicitly make this an unsigned long.  Neither the
   VAX or RT versions of pcc accept this syntax, however.
   - Win Treese, 2/21/86
 */

#if defined(ibm032) && !defined(_pcc_)
#define TM_OFFSET 2208988800UL
#else
#define TM_OFFSET 2208988800
#endif rtpc

char buffer[512];
char *ctime();
struct timeval tv;
struct timezone tz;
jmp_buf top_level;
int hiccup();
main(argc, argv)
        int argc;
        char *argv[];
{
        struct sockaddr_in sin;
        struct servent *sp;
        struct hostent *host;
        int setflg = 0;
        register int i;
        register int s;
        long hosttime;
        register int *nettime;
        char hostname[64];
        int attempts = 0, cc;
        
        strcpy (hostname, DEFAULT_TIME_SERVER);
        for (i = 1;i < argc;i++) {
                if (*argv[i] == '-') {
                        if (argv[i][1] == 's') setflg++;
                        else {
                                fprintf (stderr, "%s: Invalid argument %s\n",
                                 argv[0], argv[i]);
                                 exit (11);
                        }
                }
                else strcpy (hostname, argv[i]);
        }
        sp = getservbyname("time", "udp");
        if (sp == 0) {
                fprintf (stderr, "%s: time/udp: unknown service.\n",
                        argv[0]);
                exit (1);
        }
        host = gethostbyname(hostname);
        if (host == NULL) {
                fprintf (stderr, "%s: The timeserver host %s is unknown\n",
                         argv[0], hostname);
                exit (2);
        }
        sin.sin_family = host->h_addrtype;
        bcopy (host->h_addr, (caddr_t)&sin.sin_addr,
                        host->h_length);
        sin.sin_port = sp->s_port;
        s = socket(AF_INET, SOCK_DGRAM, 0);
        if (s < 0) {
                perror ("gettime: socket");
                exit (3);
        }
        if (connect (s, (caddr_t)&sin, sizeof (sin)) < 0) {
                perror ("gettime: connect");
                exit (4);
        }
        setjmp(top_level);
        if (attempts++ > 5) {
                close (s);
                fprintf (stderr, "Failed to get time from %s\n",
                         hostname);
                exit (10);
        }
        alarm(0);
        signal(SIGALRM, hiccup);
        alarm(5);
        send (s, buffer, 40, 0); /* Send an empty packet */
        if (gettimeofday (&tv, &tz) < 0) {
                perror ("gettime: gettimeofday");
                exit (5);
        }
        cc = recv (s, buffer, 512, 0);
        if (cc < 0) {
                perror("recv");
                close(s);
                fprintf (stderr, "Failed to get time from %s\n",
                         hostname);
                exit (7);
        }
        if (cc != 4) {
                close(s);
                fprintf(stderr,
                        "Protocol error -- received %d bytes; expected 4.\n",
                        cc);
                exit(8);
        }
        nettime = (int *)buffer;
        hosttime = (long) ntohl (*nettime) - TM_OFFSET;
        fprintf (stdout, "%s", ctime(&hosttime));
        (&tv)->tv_sec = hosttime;
        if (setflg) {
                if (settimeofday (&tv, &tz) < 0) {
                        perror ("gettime: settimeofday");
                        exit (6);
                }
        }
        close (s);
        exit (0);
}
hiccup() {
        longjmp (top_level);
}