summaryrefslogtreecommitdiff
path: root/util-linux/rdate.c
blob: 28e87323d4a2139581daaa9a4bd4499ae94ed55f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
/* vi: set sw=4 ts=4: */
/*
 * The Rdate command will ask a time server for the RFC 868 time
 *  and optionally set the system time.
 *
 * by Sterling Huxley <sterling@europa.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
*/

#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <getopt.h>
#include <string.h>
#include <time.h>
#include <stdlib.h>
#include <unistd.h>
#include "busybox.h"
#define BB_DECLARE_EXTERN
#include "messages.c"


static const int RFC_868_BIAS = 2208988800UL;

static int setdate= 0;
static int printdate= 0;

static time_t askremotedate(char *host)
{
	struct hostent *h;
	struct sockaddr_in sin;
	struct servent *tserv;
	unsigned long int nett, localt;
	int fd;

	if (!(h = gethostbyname(host))) {	/* get the IP addr */
		perror_msg("%s", host);
		return(-1);
	}
	if ((tserv = getservbyname("time", "tcp")) == NULL) { /* find port # */
		perror_msg("%s", "time");
		return(-1);
	}
	if ((fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {  /* get net connection */
		perror_msg("%s", "socket");
		return(-1);
	}

	memcpy(&sin.sin_addr, h->h_addr, sizeof(sin.sin_addr));
	sin.sin_port= tserv->s_port;
	sin.sin_family = AF_INET;

	if (connect(fd, (struct sockaddr *)&sin, sizeof(sin)) < 0) {	/* connect to time server */
		perror_msg("%s", host);
		close(fd);
		return(-1);
	}
	if (read(fd, (void *)&nett, 4) != 4) {	/* read time from server */
		close(fd);
		error_msg("%s did not send the complete time", host);
	}
	close(fd);

	/* convert from network byte order to local byte order.
	 * RFC 868 time is the number of seconds
	 *  since 00:00 (midnight) 1 January 1900 GMT
	 *  the RFC 868 time 2,208,988,800 corresponds to 00:00  1 Jan 1970 GMT
	 * Subtract the RFC 868 time  to get Linux epoch
	 */
	localt= ntohl(nett) - RFC_868_BIAS;

	return(localt);
}

int rdate_main(int argc, char **argv)
{
	time_t time;
	int opt;

	/* Interpret command line args */
	/* do special-case option parsing */
	if (argv[1] && (strcmp(argv[1], "--help") == 0))
		show_usage();

	/* do normal option parsing */
	while ((opt = getopt(argc, argv, "Hsp")) > 0) {
		switch (opt) {
			default:
			case 'H':
				show_usage();
				break;
			case 's':
				setdate++;
				break;
			case 'p':
				printdate++;
				break;
		}
	}

	/* the default action is to set the date */
	if (printdate==0 && setdate==0) setdate++;

	if (optind == argc) {
		show_usage();
	}

	if ((time= askremotedate(argv[optind])) == (time_t)-1) {
		return EXIT_FAILURE;
	}
	if (setdate) {
		if (stime(&time) < 0)
			perror_msg_and_die("Could not set time of day");
	}
	if (printdate) {
		printf("%s", ctime(&time));
	}

	return EXIT_SUCCESS;
}