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 GPL v2 or later, see file License for details.
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9 | */
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10 |
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11 | #include <sys/types.h>
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12 | #include <sys/socket.h>
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13 | #include <netinet/in.h>
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14 | #include <netdb.h>
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15 | #include <stdio.h>
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16 | #include <string.h>
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17 | #include <time.h>
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18 | #include <stdlib.h>
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19 | #include <unistd.h>
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20 | #include <signal.h>
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21 |
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22 | #include "busybox.h"
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23 |
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24 |
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25 | static const int RFC_868_BIAS = 2208988800UL;
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26 |
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27 | static void socket_timeout(int sig)
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28 | {
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29 | bb_error_msg_and_die("timeout connecting to time server");
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30 | }
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31 |
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32 | static time_t askremotedate(const char *host)
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33 | {
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34 | unsigned long nett;
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35 | struct sockaddr_in s_in;
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36 | int fd;
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37 |
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38 | bb_lookup_host(&s_in, host);
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39 | s_in.sin_port = bb_lookup_port("time", "tcp", 37);
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40 |
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41 | /* Add a timeout for dead or inaccessible servers */
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42 | alarm(10);
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43 | signal(SIGALRM, socket_timeout);
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44 |
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45 | fd = xconnect(&s_in);
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46 |
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47 | if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
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48 | bb_error_msg_and_die("%s did not send the complete time", host);
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49 | close(fd);
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50 |
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51 | /* convert from network byte order to local byte order.
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52 | * RFC 868 time is the number of seconds
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53 | * since 00:00 (midnight) 1 January 1900 GMT
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54 | * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
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55 | * Subtract the RFC 868 time to get Linux epoch
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56 | */
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57 |
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58 | return(ntohl(nett) - RFC_868_BIAS);
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59 | }
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60 |
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61 | int rdate_main(int argc, char **argv)
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62 | {
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63 | time_t remote_time;
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64 | unsigned long flags;
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65 |
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66 | bb_opt_complementally = "-1";
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67 | flags = bb_getopt_ulflags(argc, argv, "sp");
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68 |
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69 | remote_time = askremotedate(argv[optind]);
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70 |
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71 | if ((flags & 2) == 0) {
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72 | time_t current_time;
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73 |
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74 | time(¤t_time);
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75 | if (current_time == remote_time)
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76 | bb_error_msg("Current time matches remote time.");
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77 | else
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78 | if (stime(&remote_time) < 0)
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79 | bb_perror_msg_and_die("Could not set time of day");
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80 | }
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81 |
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82 | if ((flags & 1) == 0)
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83 | printf("%s", ctime(&remote_time));
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84 |
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85 | return EXIT_SUCCESS;
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86 | }
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