1/* vi: set sw=4 ts=4: */
2/*
3 * The Rdate command will ask a time server for the RFC 868 time
4 *  and optionally set the system time.
5 *
6 * by Sterling Huxley <sterling@europa.com>
7 *
8 * Licensed under GPL v2 or later, see file License for details.
9*/
10
11#include "libbb.h"
12
13enum { RFC_868_BIAS = 2208988800UL };
14
15static void socket_timeout(int sig)
16{
17	bb_error_msg_and_die("timeout connecting to time server");
18}
19
20static time_t askremotedate(const char *host)
21{
22	uint32_t nett;
23	int fd;
24
25	/* Add a timeout for dead or inaccessible servers */
26	alarm(10);
27	signal(SIGALRM, socket_timeout);
28
29	fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
30
31	if (safe_read(fd, (void *)&nett, 4) != 4)    /* read time from server */
32		bb_error_msg_and_die("%s did not send the complete time", host);
33	close(fd);
34
35	/* convert from network byte order to local byte order.
36	 * RFC 868 time is the number of seconds
37	 * since 00:00 (midnight) 1 January 1900 GMT
38	 * the RFC 868 time 2,208,988,800 corresponds to 00:00  1 Jan 1970 GMT
39	 * Subtract the RFC 868 time to get Linux epoch
40	 */
41
42	return ntohl(nett) - RFC_868_BIAS;
43}
44
45int rdate_main(int argc, char **argv);
46int rdate_main(int argc, char **argv)
47{
48	time_t remote_time;
49	unsigned long flags;
50
51	opt_complementary = "-1";
52	flags = getopt32(argv, "sp");
53
54	remote_time = askremotedate(argv[optind]);
55
56	if ((flags & 2) == 0) {
57		time_t current_time;
58
59		time(&current_time);
60		if (current_time == remote_time)
61			bb_error_msg("current time matches remote time");
62		else
63			if (stime(&remote_time) < 0)
64				bb_perror_msg_and_die("cannot set time of day");
65	}
66
67	if ((flags & 1) == 0)
68		printf("%s", ctime(&remote_time));
69
70	return EXIT_SUCCESS;
71}
72