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>
39 static char *name_buffer
;
42 dns_type_string(uint16_t type
)
68 dns_send_question(struct uloop_fd
*u
, char *question
, int type
)
70 size_t cmsg_data
[( CMSG_SPACE(sizeof(struct in_pktinfo
)) / sizeof(size_t)) + 1];
71 unsigned char buffer
[MAX_NAME_LEN
];
72 struct dns_header h
= { 0 };
73 struct dns_question q
= { 0 };
74 struct msghdr m
= { 0 };
75 struct iovec iov
[3] = { {0}, {0}, {0} };
76 struct sockaddr_in a
= { 0 };
77 struct in_pktinfo
*pkti
;
82 a
.sin_family
= AF_INET
;
83 a
.sin_addr
.s_addr
= inet_addr(MCAST_ADDR
);
84 a
.sin_port
= htons(MCAST_PORT
);
86 h
.questions
= __cpu_to_be16(1);
87 q
.type
= __cpu_to_be16(type
);
88 q
.class = __cpu_to_be16(1);
90 len
= dn_comp(question
, buffer
, MAX_NAME_LEN
, NULL
, NULL
);
95 m
.msg_namelen
= sizeof(struct sockaddr_in
);
99 memset(cmsg_data
, 0, sizeof(cmsg_data
));
100 m
.msg_control
= cmsg_data
;
101 m
.msg_controllen
= CMSG_LEN(sizeof(struct in_pktinfo
));
103 cmsg
= CMSG_FIRSTHDR(&m
);
104 cmsg
->cmsg_len
= m
.msg_controllen
;
105 cmsg
->cmsg_level
= IPPROTO_IP
;
106 cmsg
->cmsg_type
= IP_PKTINFO
;
108 inet_aton(iface_ip
, &in
);
110 pkti
= (struct in_pktinfo
*) CMSG_DATA(cmsg
);
111 pkti
->ipi_ifindex
= iface_index
;
113 iov
[0].iov_base
= &h
;
114 iov
[0].iov_len
= sizeof(struct dns_header
);
116 iov
[1].iov_base
= buffer
;
117 iov
[1].iov_len
= len
;
119 iov
[2].iov_base
= &q
;
120 iov
[2].iov_len
= sizeof(struct dns_question
);
122 if (sendmsg(u
->fd
, &m
, 0) < 0)
123 fprintf(stderr
, "failed to send question\n");
125 DBG(1, "Q <- %s %s\n", dns_type_string(type
), question
);
138 static struct dns_reply dns_reply
[1 + (MAX_ANSWER
* 3)];
139 static int dns_answer_cnt
;
142 dns_init_answer(void)
148 dns_add_answer(int type
, uint8_t *rdata
, uint16_t rdlength
)
150 struct dns_reply
*a
= &dns_reply
[dns_answer_cnt
];
151 if (dns_answer_cnt
== MAX_ANSWER
)
153 a
->rdata
= memdup(rdata
, rdlength
);
155 a
->rdlength
= rdlength
;
160 dns_send_answer(struct uloop_fd
*u
, char *answer
)
163 struct dns_header h
= { 0 };
164 struct msghdr m
= { 0 };
166 struct sockaddr_in in
= { 0 };
172 in
.sin_family
= AF_INET
;
173 in
.sin_addr
.s_addr
= inet_addr(MCAST_ADDR
);
174 in
.sin_port
= htons(MCAST_PORT
);
176 h
.answers
= __cpu_to_be16(dns_answer_cnt
);
177 h
.flags
= __cpu_to_be16(0x8400);
179 iov
= malloc(sizeof(struct iovec
) * ((dns_answer_cnt
* 3) + 1));
184 m
.msg_namelen
= sizeof(struct sockaddr_in
);
186 m
.msg_iovlen
= (dns_answer_cnt
* 3) + 1;
188 iov
[0].iov_base
= &h
;
189 iov
[0].iov_len
= sizeof(struct dns_header
);
191 for (i
= 0; i
< dns_answer_cnt
; i
++) {
192 struct dns_answer
*a
= &dns_reply
[i
].a
;
193 int id
= (i
* 3) + 1;
195 memset(a
, 0, sizeof(*a
));
196 a
->type
= __cpu_to_be16(dns_reply
[i
].type
);
197 a
->class = __cpu_to_be16(1);
198 a
->ttl
= __cpu_to_be32(announce_ttl
);
199 a
->rdlength
= __cpu_to_be16(dns_reply
[i
].rdlength
);
201 len
= dn_comp(answer
, buffer
, sizeof(buffer
), NULL
, NULL
);
205 dns_reply
[i
].buffer
= iov
[id
].iov_base
= memdup(buffer
, len
);
206 iov
[id
].iov_len
= len
;
208 iov
[id
+ 1].iov_base
= a
;
209 iov
[id
+ 1].iov_len
= sizeof(struct dns_answer
);
211 iov
[id
+ 2].iov_base
= dns_reply
[i
].rdata
;
212 iov
[id
+ 2].iov_len
= dns_reply
[i
].rdlength
;
214 DBG(1, "A <- %s %s\n", dns_type_string(dns_reply
[i
].type
), answer
);
217 if (sendmsg(u
->fd
, &m
, 0) < 0)
218 fprintf(stderr
, "failed to send question\n");
220 for (i
= 0; i
< dns_answer_cnt
; i
++) {
221 free(dns_reply
[i
].buffer
);
222 free(dns_reply
[i
].rdata
);
228 scan_name(uint8_t *buffer
, int len
)
232 while (len
&& (*buffer
!= '\0')) {
235 if (IS_COMPRESSED(l
))
243 if (!len
|| !offset
|| (*buffer
!= '\0'))
250 dns_consume_header(uint8_t **data
, int *len
)
252 struct dns_header
*h
= (struct dns_header
*) *data
;
253 uint16_t *swap
= (uint16_t *) h
;
256 if (*len
< sizeof(struct dns_header
))
259 while (endianess
--) {
260 *swap
= __be16_to_cpu(*swap
);
264 *len
-= sizeof(struct dns_header
);
265 *data
+= sizeof(struct dns_header
);
271 dns_consume_question(uint8_t **data
, int *len
)
273 struct dns_question
*q
= (struct dns_question
*) *data
;
274 uint16_t *swap
= (uint16_t *) q
;
277 if (*len
< sizeof(struct dns_question
))
280 while (endianess
--) {
281 *swap
= __be16_to_cpu(*swap
);
285 *len
-= sizeof(struct dns_question
);
286 *data
+= sizeof(struct dns_question
);
292 dns_consume_answer(uint8_t **data
, int *len
)
294 struct dns_answer
*a
= (struct dns_answer
*) *data
;
296 if (*len
< sizeof(struct dns_answer
))
299 a
->type
= __be16_to_cpu(a
->type
);
300 a
->class = __be16_to_cpu(a
->class);
301 a
->ttl
= __be32_to_cpu(a
->ttl
);
302 a
->rdlength
= __be16_to_cpu(a
->rdlength
);
304 *len
-= sizeof(struct dns_answer
);
305 *data
+= sizeof(struct dns_answer
);
311 dns_consume_name(uint8_t *base
, int blen
, uint8_t **data
, int *len
)
313 int nlen
= scan_name(*data
, *len
);
318 if (dn_expand(base
, base
+ blen
, *data
, name_buffer
, MAX_NAME_LEN
) < 0) {
319 perror("dns_consume_name/dn_expand");
332 name_buffer
= malloc(MAX_NAME_LEN
+ 1);
333 rdata_buffer
= malloc(MAX_DATA_LEN
+ 1);
335 if (!name_buffer
|| !rdata_buffer
)
338 memset(name_buffer
, 0, MAX_NAME_LEN
+ 1);
339 memset(rdata_buffer
, 0, MAX_NAME_LEN
+ 1);