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>
22 #include <sys/types.h>
23 #include <sys/socket.h>
24 #include <netinet/in.h>
25 #include <arpa/inet.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];
43 static char dns_buffer[MAX_NAME_LEN];
44 static struct blob_buf ans_buf;
47 dns_type_string(uint16_t type)
54 { TYPE_AAAA, "AAAA" },
62 for (i = 0; i < ARRAY_SIZE(type_str); i++) {
63 if (type == type_str[i].type)
64 return type_str[i].str;
71 dns_send_question(struct interface *iface, struct sockaddr *to,
72 const char *question, int type, int multicast)
74 static struct dns_header h;
75 static struct dns_question q;
76 static struct iovec iov[] = {
82 .iov_base = dns_buffer,
91 h.questions = cpu_to_be16(1);
92 q.class = cpu_to_be16((multicast ? 0 : CLASS_UNICAST) | 1);
93 q.type = cpu_to_be16(type);
95 len = dn_comp(question, (void *) dns_buffer, sizeof(dns_buffer), NULL, NULL);
101 DBG(1, "Q <- %s %s\n", dns_type_string(type), question);
102 if (interface_send_packet(iface, to, iov, ARRAY_SIZE(iov)) < 0)
103 perror("failed to send question");
115 static int dns_answer_cnt;
118 dns_init_answer(void)
121 blob_buf_init(&ans_buf, 0);
125 dns_add_answer(int type, const uint8_t *rdata, uint16_t rdlength, int ttl)
127 struct blob_attr *attr;
128 struct dns_answer *a;
130 attr = blob_new(&ans_buf, 0, sizeof(*a) + rdlength);
132 a->type = cpu_to_be16(type);
133 a->class = cpu_to_be16(1);
134 a->ttl = cpu_to_be32(ttl);
135 a->rdlength = cpu_to_be16(rdlength);
136 memcpy(a + 1, rdata, rdlength);
142 dns_send_answer(struct interface *iface, struct sockaddr *to, const char *answer)
145 struct blob_attr *attr;
146 struct dns_header h = { 0 };
154 h.answers = cpu_to_be16(dns_answer_cnt);
155 h.flags = cpu_to_be16(0x8400);
157 iov = alloca(sizeof(struct iovec) * ((dns_answer_cnt * 2) + 1));
159 iov[n_iov].iov_base = &h;
160 iov[n_iov].iov_len = sizeof(struct dns_header);
163 answer_len = dn_comp(answer, buffer, sizeof(buffer), NULL, NULL);
167 blob_for_each_attr(attr, ans_buf.head, rem) {
168 struct dns_answer *a = blob_data(attr);
170 iov[n_iov].iov_base = buffer;
171 iov[n_iov].iov_len = answer_len;
174 iov[n_iov].iov_base = blob_data(attr);
175 iov[n_iov].iov_len = blob_len(attr);
178 DBG(1, "A <- %s %s\n", dns_type_string(be16_to_cpu(a->type)), answer);
181 if (interface_send_packet(iface, to, iov, n_iov) < 0)
182 perror("failed to send answer");
186 dns_reply_a(struct interface *iface, struct sockaddr *to, int ttl)
188 struct ifaddrs *ifap, *ifa;
189 struct sockaddr_in *sa;
190 struct sockaddr_in6 *sa6;
195 for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
196 if (strcmp(ifa->ifa_name, iface->name))
198 if (ifa->ifa_addr->sa_family == AF_INET) {
199 sa = (struct sockaddr_in *) ifa->ifa_addr;
200 dns_add_answer(TYPE_A, (uint8_t *) &sa->sin_addr, 4, ttl);
202 if (ifa->ifa_addr->sa_family == AF_INET6) {
203 uint8_t ll_prefix[] = {0xfe, 0x80 };
204 sa6 = (struct sockaddr_in6 *) ifa->ifa_addr;
205 if (!memcmp(&sa6->sin6_addr, &ll_prefix, 2))
206 dns_add_answer(TYPE_AAAA, (uint8_t *) &sa6->sin6_addr, 16, ttl);
209 dns_send_answer(iface, to, mdns_hostname_local);
215 scan_name(const uint8_t *buffer, int len)
219 while (len && (*buffer != '\0')) {
222 if (IS_COMPRESSED(l))
230 if (!len || !offset || (*buffer != '\0'))
236 static struct dns_header*
237 dns_consume_header(uint8_t **data, int *len)
239 struct dns_header *h = (struct dns_header *) *data;
240 uint16_t *swap = (uint16_t *) h;
243 if (*len < sizeof(struct dns_header))
246 while (endianess--) {
247 *swap = be16_to_cpu(*swap);
251 *len -= sizeof(struct dns_header);
252 *data += sizeof(struct dns_header);
257 static struct dns_question*
258 dns_consume_question(uint8_t **data, int *len)
260 struct dns_question *q = (struct dns_question *) *data;
261 uint16_t *swap = (uint16_t *) q;
264 if (*len < sizeof(struct dns_question))
267 while (endianess--) {
268 *swap = be16_to_cpu(*swap);
272 *len -= sizeof(struct dns_question);
273 *data += sizeof(struct dns_question);
278 static struct dns_answer*
279 dns_consume_answer(uint8_t **data, int *len)
281 struct dns_answer *a = (struct dns_answer *) *data;
283 if (*len < sizeof(struct dns_answer))
286 a->type = be16_to_cpu(a->type);
287 a->class = be16_to_cpu(a->class);
288 a->ttl = be32_to_cpu(a->ttl);
289 a->rdlength = be16_to_cpu(a->rdlength);
291 *len -= sizeof(struct dns_answer);
292 *data += sizeof(struct dns_answer);
298 dns_consume_name(const uint8_t *base, int blen, uint8_t **data, int *len)
300 int nlen = scan_name(*data, *len);
305 if (dn_expand(base, base + blen, *data, name_buffer, MAX_NAME_LEN) < 0) {
306 perror("dns_consume_name/dn_expand");
316 static int parse_answer(struct interface *iface, struct sockaddr *from,
317 uint8_t *buffer, int len, uint8_t **b, int *rlen,
320 char *name = dns_consume_name(buffer, len, b, rlen);
321 struct dns_answer *a;
325 fprintf(stderr, "dropping: bad question\n");
329 a = dns_consume_answer(b, rlen);
331 fprintf(stderr, "dropping: bad question\n");
335 if ((a->class & ~CLASS_FLUSH) != CLASS_IN)
339 if (a->rdlength > *rlen) {
340 fprintf(stderr, "dropping: bad question\n");
344 *rlen -= a->rdlength;
348 cache_answer(iface, from, buffer, len, name, a, rdata, a->class & CLASS_FLUSH);
354 parse_question(struct interface *iface, struct sockaddr *from, char *name, struct dns_question *q)
356 struct sockaddr *to = NULL;
359 /* TODO: Multicast if more than one quarter of TTL has passed */
360 if (q->class & CLASS_UNICAST) {
362 if (iface->multicast)
366 DBG(1, "Q -> %s %s\n", dns_type_string(q->type), name);
370 if (!strcmp(name, mdns_hostname_local)) {
371 dns_reply_a(iface, to, announce_ttl);
372 service_reply(iface, to, NULL, NULL, announce_ttl);
377 if (!strcmp(name, C_DNS_SD)) {
378 dns_reply_a(iface, to, announce_ttl);
379 service_announce_services(iface, to, announce_ttl);
381 if (name[0] == '_') {
382 service_reply(iface, to, NULL, name, announce_ttl);
384 /* First dot separates instance name from the rest */
385 char *dot = strchr(name, '.');
389 service_reply(iface, to, name, dot + 1, announce_ttl);
398 host = strstr(name, ".local");
401 if (!strcmp(umdns_host_label, name))
402 dns_reply_a(iface, to, announce_ttl);
408 dns_handle_packet(struct interface *iface, struct sockaddr *from, uint16_t port, uint8_t *buffer, int len)
410 struct dns_header *h;
414 h = dns_consume_header(&b, &rlen);
416 fprintf(stderr, "dropping: bad header\n");
420 if (h->questions && !iface->multicast && port != MCAST_PORT)
421 /* silently drop unicast questions that dont originate from port 5353 */
424 while (h->questions-- > 0) {
425 char *name = dns_consume_name(buffer, len, &b, &rlen);
426 struct dns_question *q;
429 fprintf(stderr, "dropping: bad name\n");
433 q = dns_consume_question(&b, &rlen);
435 fprintf(stderr, "dropping: bad question\n");
439 if (!(h->flags & FLAG_RESPONSE))
440 parse_question(iface, from, name, q);
443 if (!(h->flags & FLAG_RESPONSE))
446 while (h->answers-- > 0)
447 if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))
450 while (h->authority-- > 0)
451 if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))
454 while (h->additional-- > 0)
455 if (parse_answer(iface, from, buffer, len, &b, &rlen, 1))