9c7b7ded177a1f31d7139091f1e7fd4cb4a35959
2 * Copyright (C) 2014 John Crispin <blogic@openwrt.org>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU Lesser General Public License version 2.1
6 * as published by the Free Software Foundation
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
14 #include <sys/types.h>
21 #include <sys/types.h>
22 #include <sys/socket.h>
23 #include <netinet/in.h>
24 #include <arpa/inet.h>
25 #include <asm/byteorder.h>
26 #include <arpa/nameser.h>
31 #include <libubox/uloop.h>
32 #include <libubox/usock.h>
33 #include <libubox/utils.h>
40 #include "interface.h"
42 static char name_buffer
[MAX_NAME_LEN
+ 1];
45 dns_type_string(uint16_t type
)
52 { TYPE_AAAA
, "AAAA" },
60 for (i
= 0; i
< ARRAY_SIZE(type_str
); i
++) {
61 if (type
== type_str
[i
].type
)
62 return type_str
[i
].str
;
69 dns_send_question(struct interface
*iface
, const char *question
, int type
)
71 static struct dns_header h
= {
72 .questions
= cpu_to_be16(1),
74 static struct dns_question q
= {
75 .class = cpu_to_be16(1),
77 static struct iovec iov
[] = {
83 .iov_base
= name_buffer
,
92 q
.type
= __cpu_to_be16(type
);
94 len
= dn_comp(question
, (void *) name_buffer
, sizeof(name_buffer
), NULL
, NULL
);
100 if (interface_send_packet(iface
, iov
, ARRAY_SIZE(iov
)) < 0)
101 fprintf(stderr
, "failed to send question\n");
103 DBG(1, "Q <- %s %s\n", dns_type_string(type
), question
);
116 static struct dns_reply dns_reply
[1 + (MAX_ANSWER
* 3)];
117 static int dns_answer_cnt
;
120 dns_init_answer(void)
126 dns_add_answer(int type
, const uint8_t *rdata
, uint16_t rdlength
)
128 struct dns_reply
*a
= &dns_reply
[dns_answer_cnt
];
129 if (dns_answer_cnt
== MAX_ANSWER
)
131 a
->rdata
= memdup(rdata
, rdlength
);
133 a
->rdlength
= rdlength
;
138 dns_send_answer(struct interface
*iface
, const char *answer
)
141 struct dns_header h
= { 0 };
148 h
.answers
= __cpu_to_be16(dns_answer_cnt
);
149 h
.flags
= __cpu_to_be16(0x8400);
151 iov
= alloca(sizeof(struct iovec
) * ((dns_answer_cnt
* 3) + 1));
152 iov
[0].iov_base
= &h
;
153 iov
[0].iov_len
= sizeof(struct dns_header
);
155 for (i
= 0; i
< dns_answer_cnt
; i
++) {
156 struct dns_answer
*a
= &dns_reply
[i
].a
;
157 int id
= (i
* 3) + 1;
159 memset(a
, 0, sizeof(*a
));
160 a
->type
= __cpu_to_be16(dns_reply
[i
].type
);
161 a
->class = __cpu_to_be16(1);
162 a
->ttl
= __cpu_to_be32(announce_ttl
);
163 a
->rdlength
= __cpu_to_be16(dns_reply
[i
].rdlength
);
165 len
= dn_comp(answer
, buffer
, sizeof(buffer
), NULL
, NULL
);
169 dns_reply
[i
].buffer
= iov
[id
].iov_base
= memdup(buffer
, len
);
170 iov
[id
].iov_len
= len
;
172 iov
[id
+ 1].iov_base
= a
;
173 iov
[id
+ 1].iov_len
= sizeof(struct dns_answer
);
175 iov
[id
+ 2].iov_base
= dns_reply
[i
].rdata
;
176 iov
[id
+ 2].iov_len
= dns_reply
[i
].rdlength
;
178 DBG(1, "A <- %s %s\n", dns_type_string(dns_reply
[i
].type
), answer
);
181 if (interface_send_packet(iface
, iov
, (dns_answer_cnt
* 3) + 1) < 0)
182 fprintf(stderr
, "failed to send question\n");
184 for (i
= 0; i
< dns_answer_cnt
; i
++) {
185 free(dns_reply
[i
].buffer
);
186 free(dns_reply
[i
].rdata
);
192 scan_name(const uint8_t *buffer
, int len
)
196 while (len
&& (*buffer
!= '\0')) {
199 if (IS_COMPRESSED(l
))
207 if (!len
|| !offset
|| (*buffer
!= '\0'))
213 static struct dns_header
*
214 dns_consume_header(uint8_t **data
, int *len
)
216 struct dns_header
*h
= (struct dns_header
*) *data
;
217 uint16_t *swap
= (uint16_t *) h
;
220 if (*len
< sizeof(struct dns_header
))
223 while (endianess
--) {
224 *swap
= __be16_to_cpu(*swap
);
228 *len
-= sizeof(struct dns_header
);
229 *data
+= sizeof(struct dns_header
);
234 static struct dns_question
*
235 dns_consume_question(uint8_t **data
, int *len
)
237 struct dns_question
*q
= (struct dns_question
*) *data
;
238 uint16_t *swap
= (uint16_t *) q
;
241 if (*len
< sizeof(struct dns_question
))
244 while (endianess
--) {
245 *swap
= __be16_to_cpu(*swap
);
249 *len
-= sizeof(struct dns_question
);
250 *data
+= sizeof(struct dns_question
);
255 static struct dns_answer
*
256 dns_consume_answer(uint8_t **data
, int *len
)
258 struct dns_answer
*a
= (struct dns_answer
*) *data
;
260 if (*len
< sizeof(struct dns_answer
))
263 a
->type
= __be16_to_cpu(a
->type
);
264 a
->class = __be16_to_cpu(a
->class);
265 a
->ttl
= __be32_to_cpu(a
->ttl
);
266 a
->rdlength
= __be16_to_cpu(a
->rdlength
);
268 *len
-= sizeof(struct dns_answer
);
269 *data
+= sizeof(struct dns_answer
);
275 dns_consume_name(const uint8_t *base
, int blen
, uint8_t **data
, int *len
)
277 int nlen
= scan_name(*data
, *len
);
282 if (dn_expand(base
, base
+ blen
, *data
, name_buffer
, MAX_NAME_LEN
) < 0) {
283 perror("dns_consume_name/dn_expand");
294 parse_answer(struct interface
*iface
, uint8_t *buffer
, int len
, uint8_t **b
, int *rlen
, int cache
)
296 char *name
= dns_consume_name(buffer
, len
, b
, rlen
);
297 struct dns_answer
*a
;
301 fprintf(stderr
, "dropping: bad question\n");
305 a
= dns_consume_answer(b
, rlen
);
307 fprintf(stderr
, "dropping: bad question\n");
312 if (a
->rdlength
> *rlen
) {
313 fprintf(stderr
, "dropping: bad question\n");
317 *rlen
-= a
->rdlength
;
321 cache_answer(iface
, buffer
, len
, name
, a
, rdata
);
327 parse_question(struct interface
*iface
, char *name
, struct dns_question
*q
)
331 DBG(1, "Q -> %s %s\n", dns_type_string(q
->type
), name
);
335 if (!strcmp(name
, mdns_hostname_local
))
336 service_reply(iface
, NULL
);
340 service_announce_services(iface
, name
);
341 service_reply(iface
, name
);
346 host
= strstr(name
, ".local");
349 if (!strcmp(mdns_hostname
, name
))
350 service_reply_a(iface
, q
->type
);
356 dns_handle_packet(struct interface
*iface
, uint8_t *buffer
, int len
)
358 struct dns_header
*h
;
362 h
= dns_consume_header(&b
, &rlen
);
364 fprintf(stderr
, "dropping: bad header\n");
368 while (h
->questions
-- > 0) {
369 char *name
= dns_consume_name(buffer
, len
, &b
, &rlen
);
370 struct dns_question
*q
;
373 fprintf(stderr
, "dropping: bad name\n");
377 q
= dns_consume_question(&b
, &rlen
);
379 fprintf(stderr
, "dropping: bad question\n");
383 if (!(h
->flags
& FLAG_RESPONSE
))
384 parse_question(iface
, name
, q
);
387 if (!(h
->flags
& FLAG_RESPONSE
))
390 while (h
->answers
-- > 0)
391 parse_answer(iface
, buffer
, len
, &b
, &rlen
, 1);
393 while (h
->authority
-- > 0)
394 parse_answer(iface
, buffer
, len
, &b
, &rlen
, 0);
396 while (h
->additional
-- > 0)
397 parse_answer(iface
, buffer
, len
, &b
, &rlen
, 1);