1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * The Rdate command will ask a time server for the RFC 868 time
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4 | * and optionally set the system time.
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5 | *
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6 | * by Sterling Huxley <sterling@europa.com>
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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9 | */
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10 |
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11 | //usage:#define rdate_trivial_usage
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12 | //usage: "[-sp] HOST"
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13 | //usage:#define rdate_full_usage "\n\n"
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14 | //usage: "Get and possibly set the system date/time from a remote HOST\n"
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15 | //usage: "\n -s Set the system date/time (default)"
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16 | //usage: "\n -p Print the date/time"
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17 |
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18 | #include "libbb.h"
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19 |
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20 | enum { RFC_868_BIAS = 2208988800UL };
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21 |
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22 | static void socket_timeout(int sig UNUSED_PARAM)
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23 | {
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24 | bb_error_msg_and_die("timeout connecting to time server");
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25 | }
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26 |
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27 | static time_t askremotedate(const char *host)
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28 | {
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29 | uint32_t nett;
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30 | int fd;
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31 |
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32 | /* Add a timeout for dead or inaccessible servers */
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33 | alarm(10);
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34 | signal(SIGALRM, socket_timeout);
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35 |
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36 | fd = create_and_connect_stream_or_die(host, bb_lookup_port("time", "tcp", 37));
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37 |
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38 | if (safe_read(fd, &nett, 4) != 4) /* read time from server */
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39 | bb_error_msg_and_die("%s did not send the complete time", host);
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40 | if (ENABLE_FEATURE_CLEAN_UP)
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41 | close(fd);
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42 |
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43 | /* Convert from network byte order to local byte order.
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44 | * RFC 868 time is the number of seconds
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45 | * since 00:00 (midnight) 1 January 1900 GMT
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46 | * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
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47 | * Subtract the RFC 868 time to get Linux epoch.
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48 | */
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49 |
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50 | return ntohl(nett) - RFC_868_BIAS;
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51 | }
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52 |
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53 | int rdate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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54 | int rdate_main(int argc UNUSED_PARAM, char **argv)
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55 | {
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56 | time_t remote_time;
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57 | unsigned flags;
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58 |
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59 | opt_complementary = "-1";
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60 | flags = getopt32(argv, "sp");
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61 |
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62 | remote_time = askremotedate(argv[optind]);
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63 |
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64 | if (!(flags & 2)) { /* no -p (-s may be present) */
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65 | time_t current_time;
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66 |
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67 | time(¤t_time);
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68 | if (current_time == remote_time)
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69 | bb_error_msg("current time matches remote time");
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70 | else
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71 | if (stime(&remote_time) < 0)
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72 | bb_perror_msg_and_die("can't set time of day");
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73 | }
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74 |
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75 | if (flags != 1) /* not lone -s */
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76 | printf("%s", ctime(&remote_time));
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77 |
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78 | return EXIT_SUCCESS;
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79 | }
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