diff options
Diffstat (limited to 'util-linux/rdate.c')
-rw-r--r-- | util-linux/rdate.c | 86 |
1 files changed, 86 insertions, 0 deletions
diff --git a/util-linux/rdate.c b/util-linux/rdate.c new file mode 100644 index 000000000..12105953d --- /dev/null +++ b/util-linux/rdate.c @@ -0,0 +1,86 @@ +/* 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 <sys/types.h> +#include <sys/socket.h> +#include <netinet/in.h> +#include <netdb.h> +#include <stdio.h> +#include <string.h> +#include <time.h> +#include <stdlib.h> +#include <unistd.h> +#include <signal.h> + +#include "busybox.h" + + +static const int RFC_868_BIAS = 2208988800UL; + +static void socket_timeout(int sig) +{ + bb_error_msg_and_die("timeout connecting to time server"); +} + +static time_t askremotedate(const char *host) +{ + unsigned long nett; + struct sockaddr_in s_in; + int fd; + + bb_lookup_host(&s_in, host); + s_in.sin_port = bb_lookup_port("time", "tcp", 37); + + /* Add a timeout for dead or inaccessible servers */ + alarm(10); + signal(SIGALRM, socket_timeout); + + fd = xconnect_tcp_v4(&s_in); + + 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) +{ + time_t remote_time; + unsigned long flags; + + opt_complementary = "-1"; + flags = getopt32(argc, 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; +} |