1 /* vi: set sw=4 ts=4: */
3 * The Rdate command will ask a time server for the RFC 868 time
4 * and optionally set the system time.
6 * by Sterling Huxley <sterling@europa.com>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
25 #include <sys/types.h>
26 #include <sys/socket.h>
27 #include <netinet/in.h>
36 #define BB_DECLARE_EXTERN
40 static const int RFC_868_BIAS = 2208988800UL;
42 static int setdate= 0;
43 static int printdate= 0;
45 static time_t askremotedate(char *host)
48 struct sockaddr_in sin;
49 struct servent *tserv;
50 unsigned long int nett, localt;
53 if (!(h = gethostbyname(host))) { /* get the IP addr */
54 perror_msg("%s", host);
57 if ((tserv = getservbyname("time", "tcp")) == NULL) { /* find port # */
58 perror_msg("%s", "time");
61 if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) { /* get net connection */
62 perror_msg("%s", "socket");
66 memcpy(&sin.sin_addr, h->h_addr, sizeof(sin.sin_addr));
67 sin.sin_port= tserv->s_port;
68 sin.sin_family = AF_INET;
70 if (connect(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) { /* connect to time server */
71 perror_msg("%s", host);
75 if (read(fd, (void *)&nett, 4) != 4) { /* read time from server */
77 error_msg("%s did not send the complete time", host);
81 /* convert from network byte order to local byte order.
82 * RFC 868 time is the number of seconds
83 * since 00:00 (midnight) 1 January 1900 GMT
84 * the RFC 868 time 2,208,988,800 corresponds to 00:00 1 Jan 1970 GMT
85 * Subtract the RFC 868 time to get Linux epoch
87 localt= ntohl(nett) - RFC_868_BIAS;
92 int rdate_main(int argc, char **argv)
97 /* Interpret command line args */
98 /* do special-case option parsing */
99 if (argv[1] && (strcmp(argv[1], "--help") == 0))
102 /* do normal option parsing */
103 while ((opt = getopt(argc, argv, "Hsp")) > 0) {
118 /* the default action is to set the date */
119 if (printdate==0 && setdate==0) setdate++;
121 if (optind == argc) {
125 if ((time= askremotedate(argv[optind])) == (time_t)-1) {
129 if (stime(&time) < 0)
130 perror_msg_and_die("Could not set time of day");
133 printf("%s", ctime(&time));