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.
11 //#include <sys/socket.h>
12 //#include <netinet/in.h>
19 enum { RFC_868_BIAS = 2208988800UL };
21 static void socket_timeout(int sig)
23 bb_error_msg_and_die("timeout connecting to time server");
26 static time_t askremotedate(const char *host)
31 /* Add a timeout for dead or inaccessible servers */
33 signal(SIGALRM, socket_timeout);
35 fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
37 if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
38 bb_error_msg_and_die("%s did not send the complete time", host);
41 /* convert from network byte order to local byte order.
42 * RFC 868 time is the number of seconds
43 * since 00:00 (midnight) 1 January 1900 GMT
44 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
45 * Subtract the RFC 868 time to get Linux epoch
48 return ntohl(nett) - RFC_868_BIAS;
51 int rdate_main(int argc, char **argv)
56 opt_complementary = "-1";
57 flags = getopt32(argc, argv, "sp");
59 remote_time = askremotedate(argv[optind]);
61 if ((flags & 2) == 0) {
65 if (current_time == remote_time)
66 bb_error_msg("current time matches remote time");
68 if (stime(&remote_time) < 0)
69 bb_perror_msg_and_die("cannot set time of day");
73 printf("%s", ctime(&remote_time));