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116 lines
2.7 KiB
C
116 lines
2.7 KiB
C
/* vi: set sw=4 ts=4: */
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/*
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* The Rdate command will ask a time server for the RFC 868 time
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* and optionally set the system time.
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*
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* by Sterling Huxley <sterling@europa.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*
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*/
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#include <sys/time.h>
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <getopt.h>
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#include <string.h>
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#include <time.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <signal.h>
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#include "busybox.h"
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static const int RFC_868_BIAS = 2208988800UL;
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static void socket_timeout(int sig)
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{
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bb_error_msg_and_die("timeout connecting to time server");
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}
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static time_t askremotedate(const char *host)
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{
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unsigned long int nett, localt;
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const char *port="37";
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int fd;
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if (getservbyname("time", "tcp") != NULL)
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port="time";
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/* Add a timeout for dead or non accessable servers */
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alarm(10);
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signal(SIGALRM, socket_timeout);
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fd = xconnect(host, port);
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if (safe_read(fd, (void *)&nett, 4) != 4) /* read time from server */
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bb_error_msg_and_die("%s did not send the complete time", host);
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close(fd);
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/* convert from network byte order to local byte order.
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* RFC 868 time is the number of seconds
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* since 00:00 (midnight) 1 January 1900 GMT
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* the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
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* Subtract the RFC 868 time to get Linux epoch
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*/
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localt= ntohl(nett) - RFC_868_BIAS;
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return(localt);
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}
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int rdate_main(int argc, char **argv)
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{
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time_t remote_time;
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int opt;
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int setdate = 1;
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int printdate = 1;
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/* Interpret command line args */
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while ((opt = getopt(argc, argv, "sp")) > 0) {
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switch (opt) {
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case 's':
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printdate = 0;
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setdate = 1;
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break;
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case 'p':
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printdate = 1;
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setdate = 0;
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break;
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default:
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bb_show_usage();
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}
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}
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if (optind == argc)
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bb_show_usage();
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remote_time = askremotedate(argv[optind]);
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if (setdate) {
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if (stime(&remote_time) < 0)
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bb_perror_msg_and_die("Could not set time of day");
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}
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if (printdate)
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printf("%s", ctime(&remote_time));
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return EXIT_SUCCESS;
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}
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