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 GPLv2 or later, see file LICENSE in this source tree.
11 //usage:#define rdate_trivial_usage
13 //usage:#define rdate_full_usage "\n\n"
14 //usage: "Get and possibly set the system date and time from a remote HOST\n"
15 //usage: "\n -s Set the system date and time (default)"
16 //usage: "\n -p Print the date and time"
20 enum { RFC_868_BIAS = 2208988800UL };
22 static void socket_timeout(int sig UNUSED_PARAM)
24 bb_error_msg_and_die("timeout connecting to time server");
27 static time_t askremotedate(const char *host)
32 /* Add a timeout for dead or inaccessible servers */
34 signal(SIGALRM, socket_timeout);
36 fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
38 if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
39 bb_error_msg_and_die("%s did not send the complete time", host);
42 /* convert from network byte order to local byte order.
43 * RFC 868 time is the number of seconds
44 * since 00:00 (midnight) 1 January 1900 GMT
45 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
46 * Subtract the RFC 868 time to get Linux epoch
49 return ntohl(nett) - RFC_868_BIAS;
52 int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
53 int rdate_main(int argc UNUSED_PARAM, char **argv)
58 opt_complementary = "-1";
59 flags = getopt32(argv, "sp");
61 remote_time = askremotedate(argv[optind]);
63 if ((flags & 2) == 0) {
67 if (current_time == remote_time)
68 bb_error_msg("current time matches remote time");
70 if (stime(&remote_time) < 0)
71 bb_perror_msg_and_die("can't set time of day");
75 printf("%s", ctime(&remote_time));