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.
12 #include <sys/types.h>
13 #include <sys/socket.h>
14 #include <netinet/in.h>
26 static const int RFC_868_BIAS = 2208988800UL;
28 static void socket_timeout(int sig)
30 bb_error_msg_and_die("timeout connecting to time server");
33 static time_t askremotedate(const char *host)
36 struct sockaddr_in s_in;
39 bb_lookup_host(&s_in, host);
40 s_in.sin_port = bb_lookup_port("time", "tcp", 37);
42 /* Add a timeout for dead or inaccessible servers */
44 signal(SIGALRM, socket_timeout);
48 if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
49 bb_error_msg_and_die("%s did not send the complete time", host);
52 /* convert from network byte order to local byte order.
53 * RFC 868 time is the number of seconds
54 * since 00:00 (midnight) 1 January 1900 GMT
55 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
56 * Subtract the RFC 868 time to get Linux epoch
59 return(ntohl(nett) - RFC_868_BIAS);
62 int rdate_main(int argc, char **argv)
66 unsigned long flags = bb_getopt_ulflags(argc, argv, "sp");
68 if (!flags || argc == optind)
71 remote_time = askremotedate(argv[optind]);
77 if (current_time == remote_time)
78 bb_error_msg("Current time matches remote time.");
80 if (stime(&remote_time) < 0)
81 bb_perror_msg_and_die("Could not set time of day");
83 /* No need to check for the -p flag as it's the only option left */
85 } else printf("%s", ctime(&remote_time));