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 GPLv2 or later, see file LICENSE in this source tree.
11 //usage:#define rdate_trivial_usage
13 //usage:#define rdate_full_usage "\n\n"
14 //usage: "Get and possibly set the system date/time from a remote HOST\n"
15 //usage: "\n -s Set the system date/time (default)"
16 //usage: "\n -p Print the date/time"
20 enum { RFC_868_BIAS
= 2208988800UL };
22 static void socket_timeout(int sig UNUSED_PARAM
)
24 bb_error_msg_and_die("timeout connecting to time server");
27 static time_t askremotedate(const char *host
)
32 /* Add a timeout for dead or inaccessible servers */
34 signal(SIGALRM
, socket_timeout
);
36 fd
= create_and_connect_stream_or_die(host
, bb_lookup_port("time", "tcp", 37));
38 if (safe_read(fd
, &nett
, 4) != 4) /* read time from server */
39 bb_error_msg_and_die("%s did not send the complete time", host
);
40 if (ENABLE_FEATURE_CLEAN_UP
)
43 /* Convert from network byte order to local byte order.
44 * RFC 868 time is the number of seconds
45 * since 00:00 (midnight) 1 January 1900 GMT
46 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
47 * Subtract the RFC 868 time to get Linux epoch.
50 return ntohl(nett
) - RFC_868_BIAS
;
53 int rdate_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
54 int rdate_main(int argc UNUSED_PARAM
, char **argv
)
59 opt_complementary
= "-1";
60 flags
= getopt32(argv
, "sp");
62 remote_time
= askremotedate(argv
[optind
]);
64 if (!(flags
& 2)) { /* no -p (-s may be present) */
68 if (current_time
== remote_time
)
69 bb_error_msg("current time matches remote time");
71 if (stime(&remote_time
) < 0)
72 bb_perror_msg_and_die("can't set time of day");
75 if (flags
!= 1) /* not lone -s */
76 printf("%s", ctime(&remote_time
));