1 /*
2 * dhcpcd - DHCP client daemon
3 * Copyright (c) 2006-2015 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 DUID_TIME_EPOCH 946684800
29 #define DUID_LLT 1
30 #define DUID_LL 3
31
32 #include <sys/socket.h>
33 #include <sys/types.h>
34
35 #include <net/if.h>
36 #include <net/if_arp.h>
37
38 #include <errno.h>
39 #include <stdio.h>
40 #include <stdlib.h>
41 #include <string.h>
42 #include <time.h>
43 #include <unistd.h>
44
45 #ifndef ARPHRD_NETROM
46 # define ARPHRD_NETROM 0
47 #endif
48
49 #include "common.h"
50 #include "dhcpcd.h"
51 #include "duid.h"
52
53 static size_t
duid_make(unsigned char * d,const struct interface * ifp,uint16_t type)54 duid_make(unsigned char *d, const struct interface *ifp, uint16_t type)
55 {
56 unsigned char *p;
57 uint16_t u16;
58 time_t t;
59 uint32_t u32;
60
61 p = d;
62 u16 = htons(type);
63 memcpy(p, &u16, 2);
64 p += 2;
65 u16 = htons(ifp->family);
66 memcpy(p, &u16, 2);
67 p += 2;
68 if (type == DUID_LLT) {
69 /* time returns seconds from jan 1 1970, but DUID-LLT is
70 * seconds from jan 1 2000 modulo 2^32 */
71 t = time(NULL) - DUID_TIME_EPOCH;
72 u32 = htonl((uint32_t)t & 0xffffffff);
73 memcpy(p, &u32, 4);
74 p += 4;
75 }
76 /* Finally, add the MAC address of the interface */
77 memcpy(p, ifp->hwaddr, ifp->hwlen);
78 p += ifp->hwlen;
79 return (size_t)(p - d);
80 }
81
82 #define DUID_STRLEN DUID_LEN * 3
83 static size_t
duid_get(unsigned char * d,const struct interface * ifp)84 duid_get(unsigned char *d, const struct interface *ifp)
85 {
86 FILE *fp;
87 int x = 0;
88 size_t len = 0;
89 char line[DUID_STRLEN];
90 const struct interface *ifp2;
91
92 /* If we already have a DUID then use it as it's never supposed
93 * to change once we have one even if the interfaces do */
94 if ((fp = fopen(DUID, "r"))) {
95 while (fgets(line, DUID_STRLEN, fp)) {
96 len = strlen(line);
97 if (len) {
98 if (line[len - 1] == '\n')
99 line[len - 1] = '\0';
100 }
101 len = hwaddr_aton(NULL, line);
102 if (len && len <= DUID_LEN) {
103 hwaddr_aton(d, line);
104 break;
105 }
106 len = 0;
107 }
108 fclose(fp);
109 if (len)
110 return len;
111 } else {
112 if (errno != ENOENT)
113 logger(ifp->ctx, LOG_ERR,
114 "error reading DUID: %s: %m", DUID);
115 }
116
117 /* No file? OK, lets make one based on our interface */
118 if (ifp->family == ARPHRD_NETROM) {
119 logger(ifp->ctx, LOG_WARNING,
120 "%s: is a NET/ROM psuedo interface", ifp->name);
121 TAILQ_FOREACH(ifp2, ifp->ctx->ifaces, next) {
122 if (ifp2->family != ARPHRD_NETROM)
123 break;
124 }
125 if (ifp2) {
126 ifp = ifp2;
127 logger(ifp->ctx, LOG_WARNING,
128 "picked interface %s to generate a DUID",
129 ifp->name);
130 } else {
131 logger(ifp->ctx, LOG_WARNING,
132 "no interfaces have a fixed hardware address");
133 return duid_make(d, ifp, DUID_LL);
134 }
135 }
136
137 if (!(fp = fopen(DUID, "w"))) {
138 logger(ifp->ctx, LOG_ERR, "error writing DUID: %s: %m", DUID);
139 return duid_make(d, ifp, DUID_LL);
140 }
141 len = duid_make(d, ifp, DUID_LLT);
142 x = fprintf(fp, "%s\n", hwaddr_ntoa(d, len, line, sizeof(line)));
143 fclose(fp);
144 /* Failed to write the duid? scrub it, we cannot use it */
145 if (x < 1) {
146 logger(ifp->ctx, LOG_ERR, "error writing DUID: %s: %m", DUID);
147 unlink(DUID);
148 return duid_make(d, ifp, DUID_LL);
149 }
150 return len;
151 }
152
duid_init(const struct interface * ifp)153 size_t duid_init(const struct interface *ifp)
154 {
155
156 if (ifp->ctx->duid == NULL) {
157 ifp->ctx->duid = malloc(DUID_LEN);
158 if (ifp->ctx->duid == NULL) {
159 logger(ifp->ctx, LOG_ERR, "%s: %m", __func__);
160 return 0;
161 }
162 ifp->ctx->duid_len = duid_get(ifp->ctx->duid, ifp);
163 }
164 return ifp->ctx->duid_len;
165 }
166