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>
39 char rdata_buffer[MAX_DATA_LEN + 1];
40 static char name_buffer[MAX_NAME_LEN + 1];
43 dns_type_string(uint16_t type)
69 dns_send_question(struct uloop_fd *u, char *question, int type)
71 static size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
72 static struct dns_header h = {
73 .questions = cpu_to_be16(1),
75 static struct dns_question q = {
76 .class = cpu_to_be16(1),
78 static struct iovec iov[] = {
84 .iov_base = name_buffer,
91 static struct sockaddr_in a = {
92 .sin_family = AF_INET,
93 .sin_port = htons(MCAST_PORT),
95 static struct msghdr m = {
96 .msg_name = (struct sockaddr *) &a,
97 .msg_namelen = sizeof(a),
99 .msg_iovlen = ARRAY_SIZE(iov),
100 .msg_control = cmsg_data,
101 .msg_controllen = CMSG_LEN(sizeof(struct in_pktinfo)),
103 struct in_pktinfo *pkti;
104 struct cmsghdr *cmsg;
107 a.sin_addr.s_addr = inet_addr(MCAST_ADDR);
108 q.type = __cpu_to_be16(type);
110 len = dn_comp(question, (void *) name_buffer, sizeof(name_buffer), NULL, NULL);
114 iov[1].iov_len = len;
116 memset(cmsg_data, 0, sizeof(cmsg_data));
118 cmsg = CMSG_FIRSTHDR(&m);
119 cmsg->cmsg_len = m.msg_controllen;
120 cmsg->cmsg_level = IPPROTO_IP;
121 cmsg->cmsg_type = IP_PKTINFO;
123 pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
124 pkti->ipi_ifindex = iface_index;
126 if (sendmsg(u->fd, &m, 0) < 0)
127 fprintf(stderr, "failed to send question\n");
129 DBG(1, "Q <- %s %s\n", dns_type_string(type), question);
142 static struct dns_reply dns_reply[1 + (MAX_ANSWER * 3)];
143 static int dns_answer_cnt;
146 dns_init_answer(void)
152 dns_add_answer(int type, uint8_t *rdata, uint16_t rdlength)
154 struct dns_reply *a = &dns_reply[dns_answer_cnt];
155 if (dns_answer_cnt == MAX_ANSWER)
157 a->rdata = memdup(rdata, rdlength);
159 a->rdlength = rdlength;
164 dns_send_answer(struct uloop_fd *u, char *answer)
167 struct dns_header h = { 0 };
168 struct msghdr m = { 0 };
170 struct sockaddr_in in = { 0 };
176 in.sin_family = AF_INET;
177 in.sin_addr.s_addr = inet_addr(MCAST_ADDR);
178 in.sin_port = htons(MCAST_PORT);
180 h.answers = __cpu_to_be16(dns_answer_cnt);
181 h.flags = __cpu_to_be16(0x8400);
183 iov = malloc(sizeof(struct iovec) * ((dns_answer_cnt * 3) + 1));
188 m.msg_namelen = sizeof(struct sockaddr_in);
190 m.msg_iovlen = (dns_answer_cnt * 3) + 1;
192 iov[0].iov_base = &h;
193 iov[0].iov_len = sizeof(struct dns_header);
195 for (i = 0; i < dns_answer_cnt; i++) {
196 struct dns_answer *a = &dns_reply[i].a;
197 int id = (i * 3) + 1;
199 memset(a, 0, sizeof(*a));
200 a->type = __cpu_to_be16(dns_reply[i].type);
201 a->class = __cpu_to_be16(1);
202 a->ttl = __cpu_to_be32(announce_ttl);
203 a->rdlength = __cpu_to_be16(dns_reply[i].rdlength);
205 len = dn_comp(answer, buffer, sizeof(buffer), NULL, NULL);
209 dns_reply[i].buffer = iov[id].iov_base = memdup(buffer, len);
210 iov[id].iov_len = len;
212 iov[id + 1].iov_base = a;
213 iov[id + 1].iov_len = sizeof(struct dns_answer);
215 iov[id + 2].iov_base = dns_reply[i].rdata;
216 iov[id + 2].iov_len = dns_reply[i].rdlength;
218 DBG(1, "A <- %s %s\n", dns_type_string(dns_reply[i].type), answer);
221 if (sendmsg(u->fd, &m, 0) < 0)
222 fprintf(stderr, "failed to send question\n");
224 for (i = 0; i < dns_answer_cnt; i++) {
225 free(dns_reply[i].buffer);
226 free(dns_reply[i].rdata);
232 scan_name(uint8_t *buffer, int len)
236 while (len && (*buffer != '\0')) {
239 if (IS_COMPRESSED(l))
247 if (!len || !offset || (*buffer != '\0'))
254 dns_consume_header(uint8_t **data, int *len)
256 struct dns_header *h = (struct dns_header *) *data;
257 uint16_t *swap = (uint16_t *) h;
260 if (*len < sizeof(struct dns_header))
263 while (endianess--) {
264 *swap = __be16_to_cpu(*swap);
268 *len -= sizeof(struct dns_header);
269 *data += sizeof(struct dns_header);
275 dns_consume_question(uint8_t **data, int *len)
277 struct dns_question *q = (struct dns_question *) *data;
278 uint16_t *swap = (uint16_t *) q;
281 if (*len < sizeof(struct dns_question))
284 while (endianess--) {
285 *swap = __be16_to_cpu(*swap);
289 *len -= sizeof(struct dns_question);
290 *data += sizeof(struct dns_question);
296 dns_consume_answer(uint8_t **data, int *len)
298 struct dns_answer *a = (struct dns_answer *) *data;
300 if (*len < sizeof(struct dns_answer))
303 a->type = __be16_to_cpu(a->type);
304 a->class = __be16_to_cpu(a->class);
305 a->ttl = __be32_to_cpu(a->ttl);
306 a->rdlength = __be16_to_cpu(a->rdlength);
308 *len -= sizeof(struct dns_answer);
309 *data += sizeof(struct dns_answer);
315 dns_consume_name(uint8_t *base, int blen, uint8_t **data, int *len)
317 int nlen = scan_name(*data, *len);
322 if (dn_expand(base, base + blen, *data, name_buffer, MAX_NAME_LEN) < 0) {
323 perror("dns_consume_name/dn_expand");