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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 GPLv2 or later, see file LICENSE in this source tree. */ //usage:#define rdate_trivial_usage //usage: "[-sp] HOST" //usage:#define rdate_full_usage "\n\n" //usage: "Get and possibly set system time from a remote HOST\n" //usage: "\n -s Set system time (default)" //usage: "\n -p Print time" #include "libbb.h" enum { RFC_868_BIAS = 2208988800UL }; static void socket_timeout(int sig UNUSED_PARAM) { 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, &nett, 4) != 4) /* read time from server */ bb_error_msg_and_die("%s: %s", host, "short read"); if (ENABLE_FEATURE_CLEAN_UP) 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 UNUSED_PARAM, char **argv) { time_t remote_time; unsigned flags; opt_complementary = "-1"; flags = getopt32(argv, "sp"); remote_time = askremotedate(argv[optind]); if (!(flags & 2)) { /* no -p (-s may be present) */ 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("can't set time of day"); } if (flags != 1) /* not lone -s */ printf("%s", ctime(&remote_time)); return EXIT_SUCCESS; } |