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126 lines
3.2 KiB
C
126 lines
3.2 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 "busybox.h"
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static const int RFC_868_BIAS = 2208988800UL;
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static time_t askremotedate(const char *host)
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{
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struct hostent *h;
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struct sockaddr_in s_in;
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struct servent *tserv;
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unsigned long int nett, localt;
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int fd;
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if (!(h = gethostbyname(host))) /* get the IP addr */
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perror_msg_and_die("%s", host);
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if ((tserv = getservbyname("time", "tcp")) == NULL) /* find port # */
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perror_msg_and_die("%s", "time");
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if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) /* get net connection */
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perror_msg_and_die("%s", "socket");
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memcpy(&s_in.sin_addr, h->h_addr, sizeof(s_in.sin_addr));
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s_in.sin_port= tserv->s_port;
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s_in.sin_family = AF_INET;
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if (connect(fd, (struct sockaddr *)&s_in, sizeof(s_in)) < 0) /* connect to time server */
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perror_msg_and_die("%s", host);
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if (read(fd, (void *)&nett, 4) != 4) /* read time from server */
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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 = 0;
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int printdate= 0;
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/* Interpret command line args */
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/* do special-case option parsing */
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if (argv[1] && (strcmp(argv[1], "--help") == 0))
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show_usage();
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/* do normal option parsing */
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while ((opt = getopt(argc, argv, "Hsp")) > 0) {
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switch (opt) {
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default:
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case 'H':
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show_usage();
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break;
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case 's':
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setdate++;
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break;
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case 'p':
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printdate++;
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break;
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}
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}
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/* the default action is to set the date */
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if (printdate==0 && setdate==0) setdate++;
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if (optind == argc)
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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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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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