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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.
*/
#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, (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 UNUSED_PARAM, 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("can't set time of day");
}
if ((flags & 1) == 0)
printf("%s", ctime(&remote_time));
return EXIT_SUCCESS;
}
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