1/*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2008 Roy Marples <roy@marples.name>
4 * All rights reserved
5
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#define THIRTY_YEARS_IN_SECONDS    946707779
29
30#include <errno.h>
31#include <stdio.h>
32#include <stdlib.h>
33#include <string.h>
34#include <time.h>
35#include <unistd.h>
36
37#include "common.h"
38#include "duid.h"
39#include "net.h"
40
41size_t
42get_duid(unsigned char *duid, const struct interface *iface)
43{
44	FILE *f;
45	uint16_t type = 0;
46	uint16_t hw = 0;
47	uint32_t ul;
48	time_t t;
49	int x = 0;
50	unsigned char *p = duid;
51	size_t len = 0;
52	char *line;
53
54	/* If we already have a DUID then use it as it's never supposed
55	 * to change once we have one even if the interfaces do */
56	if ((f = fopen(DUID, "r"))) {
57		while ((line = get_line(f))) {
58			len = hwaddr_aton(NULL, line);
59			if (len && len <= DUID_LEN) {
60				hwaddr_aton(duid, line);
61				break;
62			}
63			len = 0;
64		}
65		fclose(f);
66		if (len)
67			return len;
68	} else {
69		if (errno != ENOENT)
70			return 0;
71	}
72
73	/* No file? OK, lets make one based on our interface */
74	if (!(f = fopen(DUID, "w")))
75		return 0;
76	type = htons(1); /* DUI-D-LLT */
77	memcpy(p, &type, 2);
78	p += 2;
79	hw = htons(iface->family);
80	memcpy(p, &hw, 2);
81	p += 2;
82	/* time returns seconds from jan 1 1970, but DUID-LLT is
83	 * seconds from jan 1 2000 modulo 2^32 */
84	t = time(NULL) - THIRTY_YEARS_IN_SECONDS;
85	ul = htonl(t & 0xffffffff);
86	memcpy(p, &ul, 4);
87	p += 4;
88	/* Finally, add the MAC address of the interface */
89	memcpy(p, iface->hwaddr, iface->hwlen);
90	p += iface->hwlen;
91	len = p - duid;
92	x = fprintf(f, "%s\n", hwaddr_ntoa(duid, len));
93	fclose(f);
94	/* Failed to write the duid? scrub it, we cannot use it */
95	if (x < 1) {
96		len = 0;
97		unlink(DUID);
98	}
99	return len;
100}
101