blob: 6e35cd5190bcbc595a7dd1cc9de19e5196602a6b
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 GPLv2 or later, see file LICENSE in this source tree. |
9 | */ |
10 | |
11 | //usage:#define rdate_trivial_usage |
12 | //usage: "[-sp] HOST" |
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" |
17 | |
18 | #include "libbb.h" |
19 | |
20 | enum { RFC_868_BIAS = 2208988800UL }; |
21 | |
22 | static void socket_timeout(int sig UNUSED_PARAM) |
23 | { |
24 | bb_error_msg_and_die("timeout connecting to time server"); |
25 | } |
26 | |
27 | static time_t askremotedate(const char *host) |
28 | { |
29 | uint32_t nett; |
30 | int fd; |
31 | |
32 | /* Add a timeout for dead or inaccessible servers */ |
33 | alarm(10); |
34 | signal(SIGALRM, socket_timeout); |
35 | |
36 | fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37)); |
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) |
41 | close(fd); |
42 | |
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. |
48 | */ |
49 | |
50 | return ntohl(nett) - RFC_868_BIAS; |
51 | } |
52 | |
53 | int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
54 | int rdate_main(int argc UNUSED_PARAM, char **argv) |
55 | { |
56 | time_t remote_time; |
57 | unsigned flags; |
58 | |
59 | opt_complementary = "-1"; |
60 | flags = getopt32(argv, "sp"); |
61 | |
62 | remote_time = askremotedate(argv[optind]); |
63 | |
64 | if (!(flags & 2)) { /* no -p (-s may be present) */ |
65 | time_t current_time; |
66 | |
67 | time(¤t_time); |
68 | if (current_time == remote_time) |
69 | bb_error_msg("current time matches remote time"); |
70 | else |
71 | if (stime(&remote_time) < 0) |
72 | bb_perror_msg_and_die("can't set time of day"); |
73 | } |
74 | |
75 | if (flags != 1) /* not lone -s */ |
76 | printf("%s", ctime(&remote_time)); |
77 | |
78 | return EXIT_SUCCESS; |
79 | } |
80 |