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/* vi: set sw=4 ts=4: */ /* * The Rdate command will ask a time server for the RFC 868 time * and optionally set the system time. * * by Sterling Huxley <sterling@europa.com> * * Licensed under GPL v2 or later, see file License for details. */ #include "libbb.h" enum { RFC_868_BIAS = 2208988800UL }; static void socket_timeout(int sig ATTRIBUTE_UNUSED) { bb_error_msg_and_die("timeout connecting to time server"); } static time_t askremotedate(const char *host) { uint32_t nett; int fd; /* Add a timeout for dead or inaccessible servers */ alarm(10); signal(SIGALRM, socket_timeout); fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37)); if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */ bb_error_msg_and_die("%s did not send the complete time", host); close(fd); /* convert from network byte order to local byte order. * RFC 868 time is the number of seconds * since 00:00 (midnight) 1 January 1900 GMT * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT * Subtract the RFC 868 time to get Linux epoch */ return ntohl(nett) - RFC_868_BIAS; } int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int rdate_main(int argc ATTRIBUTE_UNUSED, char **argv) { time_t remote_time; unsigned long flags; opt_complementary = "-1"; flags = getopt32(argv, "sp"); remote_time = askremotedate(argv[optind]); if ((flags & 2) == 0) { time_t current_time; time(¤t_time); if (current_time == remote_time) bb_error_msg("current time matches remote time"); else if (stime(&remote_time) < 0) bb_perror_msg_and_die("cannot set time of day"); } if ((flags & 1) == 0) printf("%s", ctime(&remote_time)); return EXIT_SUCCESS; } |