1 /* vi: set sw=4 ts=4: */
3 * The Rdate command will ask a time server for the RFC 868 time
4 * and optionally set the system time.
6 * by Sterling Huxley <sterling@europa.com>
8 * Licensed under GPL v2 or later, see file License for details.
13 enum { RFC_868_BIAS = 2208988800UL };
15 static void socket_timeout(int sig)
17 bb_error_msg_and_die("timeout connecting to time server");
20 static time_t askremotedate(const char *host)
25 /* Add a timeout for dead or inaccessible servers */
27 signal(SIGALRM, socket_timeout);
29 fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
31 if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
32 bb_error_msg_and_die("%s did not send the complete time", host);
35 /* convert from network byte order to local byte order.
36 * RFC 868 time is the number of seconds
37 * since 00:00 (midnight) 1 January 1900 GMT
38 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
39 * Subtract the RFC 868 time to get Linux epoch
42 return ntohl(nett) - RFC_868_BIAS;
45 int rdate_main(int argc, char **argv);
46 int rdate_main(int argc, char **argv)
51 opt_complementary = "-1";
52 flags = getopt32(argv, "sp");
54 remote_time = askremotedate(argv[optind]);
56 if ((flags & 2) == 0) {
60 if (current_time == remote_time)
61 bb_error_msg("current time matches remote time");
63 if (stime(&remote_time) < 0)
64 bb_perror_msg_and_die("cannot set time of day");
68 printf("%s", ctime(&remote_time));