1 /***
2 This file is part of avahi.
3
4 avahi is free software; you can redistribute it and/or modify it
5 under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 avahi is distributed in the hope that it will be useful, but WITHOUT
10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12 Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with avahi; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
17 USA.
18 ***/
19
20 #ifdef HAVE_CONFIG_H
21 #include <config.h>
22 #endif
23
24 #include <stdlib.h>
25 #include <string.h>
26 #include <stdio.h>
27 #include <assert.h>
28
29 #include <sys/types.h>
30 #include <netinet/in.h>
31
32 #include <avahi-common/defs.h>
33 #include <avahi-common/domain.h>
34 #include "avahi-common/avahi-malloc.h"
35
36 #include "dns.h"
37 #include "log.h"
38
avahi_dns_packet_new(unsigned mtu)39 AvahiDnsPacket* avahi_dns_packet_new(unsigned mtu) {
40 AvahiDnsPacket *p;
41 size_t max_size;
42
43 if (mtu <= 0)
44 max_size = AVAHI_DNS_PACKET_SIZE_MAX;
45 else if (mtu >= AVAHI_DNS_PACKET_EXTRA_SIZE)
46 max_size = mtu - AVAHI_DNS_PACKET_EXTRA_SIZE;
47 else
48 max_size = 0;
49
50 if (max_size < AVAHI_DNS_PACKET_HEADER_SIZE)
51 max_size = AVAHI_DNS_PACKET_HEADER_SIZE;
52
53 if (!(p = avahi_malloc(sizeof(AvahiDnsPacket) + max_size)))
54 return p;
55
56 p->size = p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
57 p->max_size = max_size;
58 p->name_table = NULL;
59 p->data = NULL;
60
61 memset(AVAHI_DNS_PACKET_DATA(p), 0, p->size);
62 return p;
63 }
64
avahi_dns_packet_new_query(unsigned mtu)65 AvahiDnsPacket* avahi_dns_packet_new_query(unsigned mtu) {
66 AvahiDnsPacket *p;
67
68 if (!(p = avahi_dns_packet_new(mtu)))
69 return NULL;
70
71 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 0, 0, 0, 0, 0, 0));
72 return p;
73 }
74
avahi_dns_packet_new_response(unsigned mtu,int aa)75 AvahiDnsPacket* avahi_dns_packet_new_response(unsigned mtu, int aa) {
76 AvahiDnsPacket *p;
77
78 if (!(p = avahi_dns_packet_new(mtu)))
79 return NULL;
80
81 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(1, 0, aa, 0, 0, 0, 0, 0, 0, 0));
82 return p;
83 }
84
avahi_dns_packet_new_reply(AvahiDnsPacket * p,unsigned mtu,int copy_queries,int aa)85 AvahiDnsPacket* avahi_dns_packet_new_reply(AvahiDnsPacket* p, unsigned mtu, int copy_queries, int aa) {
86 AvahiDnsPacket *r;
87 assert(p);
88
89 if (!(r = avahi_dns_packet_new_response(mtu, aa)))
90 return NULL;
91
92 if (copy_queries) {
93 unsigned saved_rindex;
94 uint32_t n;
95
96 saved_rindex = p->rindex;
97 p->rindex = AVAHI_DNS_PACKET_HEADER_SIZE;
98
99 for (n = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); n > 0; n--) {
100 AvahiKey *k;
101 int unicast_response;
102
103 if ((k = avahi_dns_packet_consume_key(p, &unicast_response))) {
104 avahi_dns_packet_append_key(r, k, unicast_response);
105 avahi_key_unref(k);
106 }
107 }
108
109 p->rindex = saved_rindex;
110
111 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_QDCOUNT, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT));
112 }
113
114 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_ID, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID));
115
116 avahi_dns_packet_set_field(r, AVAHI_DNS_FIELD_FLAGS,
117 (avahi_dns_packet_get_field(r, AVAHI_DNS_FIELD_FLAGS) & ~AVAHI_DNS_FLAG_OPCODE) |
118 (avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_OPCODE));
119
120 return r;
121 }
122
123
avahi_dns_packet_free(AvahiDnsPacket * p)124 void avahi_dns_packet_free(AvahiDnsPacket *p) {
125 assert(p);
126
127 if (p->name_table)
128 avahi_hashmap_free(p->name_table);
129
130 avahi_free(p);
131 }
132
avahi_dns_packet_set_field(AvahiDnsPacket * p,unsigned idx,uint16_t v)133 void avahi_dns_packet_set_field(AvahiDnsPacket *p, unsigned idx, uint16_t v) {
134 assert(p);
135 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
136
137 ((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx] = htons(v);
138 }
139
avahi_dns_packet_get_field(AvahiDnsPacket * p,unsigned idx)140 uint16_t avahi_dns_packet_get_field(AvahiDnsPacket *p, unsigned idx) {
141 assert(p);
142 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
143
144 return ntohs(((uint16_t*) AVAHI_DNS_PACKET_DATA(p))[idx]);
145 }
146
avahi_dns_packet_inc_field(AvahiDnsPacket * p,unsigned idx)147 void avahi_dns_packet_inc_field(AvahiDnsPacket *p, unsigned idx) {
148 assert(p);
149 assert(idx < AVAHI_DNS_PACKET_HEADER_SIZE);
150
151 avahi_dns_packet_set_field(p, idx, avahi_dns_packet_get_field(p, idx) + 1);
152 }
153
154
name_table_cleanup(void * key,void * value,void * user_data)155 static void name_table_cleanup(void *key, void *value, void *user_data) {
156 AvahiDnsPacket *p = user_data;
157
158 if ((uint8_t*) value >= AVAHI_DNS_PACKET_DATA(p) + p->size)
159 avahi_hashmap_remove(p->name_table, key);
160 }
161
avahi_dns_packet_cleanup_name_table(AvahiDnsPacket * p)162 void avahi_dns_packet_cleanup_name_table(AvahiDnsPacket *p) {
163 if (p->name_table)
164 avahi_hashmap_foreach(p->name_table, name_table_cleanup, p);
165 }
166
avahi_dns_packet_append_name(AvahiDnsPacket * p,const char * name)167 uint8_t* avahi_dns_packet_append_name(AvahiDnsPacket *p, const char *name) {
168 uint8_t *d, *saved_ptr = NULL;
169 size_t saved_size;
170
171 assert(p);
172 assert(name);
173
174 saved_size = p->size;
175 saved_ptr = avahi_dns_packet_extend(p, 0);
176
177 while (*name) {
178 uint8_t* prev;
179 const char *pname;
180 char label[64], *u;
181
182 /* Check whether we can compress this name. */
183
184 if (p->name_table && (prev = avahi_hashmap_lookup(p->name_table, name))) {
185 unsigned idx;
186
187 assert(prev >= AVAHI_DNS_PACKET_DATA(p));
188 idx = (unsigned) (prev - AVAHI_DNS_PACKET_DATA(p));
189
190 assert(idx < p->size);
191
192 if (idx < 0x4000) {
193 uint8_t *t;
194 if (!(t = (uint8_t*) avahi_dns_packet_extend(p, sizeof(uint16_t))))
195 return NULL;
196
197 t[0] = (uint8_t) ((0xC000 | idx) >> 8);
198 t[1] = (uint8_t) idx;
199 return saved_ptr;
200 }
201 }
202
203 pname = name;
204
205 if (!(avahi_unescape_label(&name, label, sizeof(label))))
206 goto fail;
207
208 if (!(d = avahi_dns_packet_append_string(p, label)))
209 goto fail;
210
211 if (!p->name_table)
212 /* This works only for normalized domain names */
213 p->name_table = avahi_hashmap_new(avahi_string_hash, avahi_string_equal, avahi_free, NULL);
214
215 if (!(u = avahi_strdup(pname)))
216 avahi_log_error("avahi_strdup() failed.");
217 else
218 avahi_hashmap_insert(p->name_table, u, d);
219 }
220
221 if (!(d = avahi_dns_packet_extend(p, 1)))
222 goto fail;
223
224 *d = 0;
225
226 return saved_ptr;
227
228 fail:
229 p->size = saved_size;
230 avahi_dns_packet_cleanup_name_table(p);
231
232 return NULL;
233 }
234
avahi_dns_packet_append_uint16(AvahiDnsPacket * p,uint16_t v)235 uint8_t* avahi_dns_packet_append_uint16(AvahiDnsPacket *p, uint16_t v) {
236 uint8_t *d;
237 assert(p);
238
239 if (!(d = avahi_dns_packet_extend(p, sizeof(uint16_t))))
240 return NULL;
241
242 d[0] = (uint8_t) (v >> 8);
243 d[1] = (uint8_t) v;
244 return d;
245 }
246
avahi_dns_packet_append_uint32(AvahiDnsPacket * p,uint32_t v)247 uint8_t *avahi_dns_packet_append_uint32(AvahiDnsPacket *p, uint32_t v) {
248 uint8_t *d;
249 assert(p);
250
251 if (!(d = avahi_dns_packet_extend(p, sizeof(uint32_t))))
252 return NULL;
253
254 d[0] = (uint8_t) (v >> 24);
255 d[1] = (uint8_t) (v >> 16);
256 d[2] = (uint8_t) (v >> 8);
257 d[3] = (uint8_t) v;
258
259 return d;
260 }
261
avahi_dns_packet_append_bytes(AvahiDnsPacket * p,const void * b,size_t l)262 uint8_t *avahi_dns_packet_append_bytes(AvahiDnsPacket *p, const void *b, size_t l) {
263 uint8_t* d;
264
265 assert(p);
266 assert(b);
267 assert(l);
268
269 if (!(d = avahi_dns_packet_extend(p, l)))
270 return NULL;
271
272 memcpy(d, b, l);
273 return d;
274 }
275
avahi_dns_packet_append_string(AvahiDnsPacket * p,const char * s)276 uint8_t* avahi_dns_packet_append_string(AvahiDnsPacket *p, const char *s) {
277 uint8_t* d;
278 size_t k;
279
280 assert(p);
281 assert(s);
282
283 if ((k = strlen(s)) >= 255)
284 k = 255;
285
286 if (!(d = avahi_dns_packet_extend(p, k+1)))
287 return NULL;
288
289 *d = (uint8_t) k;
290 memcpy(d+1, s, k);
291
292 return d;
293 }
294
avahi_dns_packet_extend(AvahiDnsPacket * p,size_t l)295 uint8_t *avahi_dns_packet_extend(AvahiDnsPacket *p, size_t l) {
296 uint8_t *d;
297
298 assert(p);
299
300 if (p->size+l > p->max_size)
301 return NULL;
302
303 d = AVAHI_DNS_PACKET_DATA(p) + p->size;
304 p->size += l;
305
306 return d;
307 }
308
avahi_dns_packet_check_valid(AvahiDnsPacket * p)309 int avahi_dns_packet_check_valid(AvahiDnsPacket *p) {
310 uint16_t flags;
311 assert(p);
312
313 if (p->size < AVAHI_DNS_PACKET_HEADER_SIZE)
314 return -1;
315
316 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
317
318 if (flags & AVAHI_DNS_FLAG_OPCODE)
319 return -1;
320
321 return 0;
322 }
323
avahi_dns_packet_check_valid_multicast(AvahiDnsPacket * p)324 int avahi_dns_packet_check_valid_multicast(AvahiDnsPacket *p) {
325 uint16_t flags;
326 assert(p);
327
328 if (avahi_dns_packet_check_valid(p) < 0)
329 return -1;
330
331 flags = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS);
332
333 if (flags & AVAHI_DNS_FLAG_RCODE)
334 return -1;
335
336 return 0;
337 }
338
avahi_dns_packet_is_query(AvahiDnsPacket * p)339 int avahi_dns_packet_is_query(AvahiDnsPacket *p) {
340 assert(p);
341
342 return !(avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & AVAHI_DNS_FLAG_QR);
343 }
344
consume_labels(AvahiDnsPacket * p,unsigned idx,char * ret_name,size_t l)345 static int consume_labels(AvahiDnsPacket *p, unsigned idx, char *ret_name, size_t l) {
346 int ret = 0;
347 int compressed = 0;
348 int first_label = 1;
349 unsigned label_ptr;
350 int i;
351 assert(p && ret_name && l);
352
353 for (i = 0; i < AVAHI_DNS_LABELS_MAX; i++) {
354 uint8_t n;
355
356 if (idx+1 > p->size)
357 return -1;
358
359 n = AVAHI_DNS_PACKET_DATA(p)[idx];
360
361 if (!n) {
362 idx++;
363 if (!compressed)
364 ret++;
365
366 if (l < 1)
367 return -1;
368 *ret_name = 0;
369
370 return ret;
371
372 } else if (n <= 63) {
373 /* Uncompressed label */
374 idx++;
375 if (!compressed)
376 ret++;
377
378 if (idx + n > p->size)
379 return -1;
380
381 if ((size_t) n + 1 > l)
382 return -1;
383
384 if (!first_label) {
385 *(ret_name++) = '.';
386 l--;
387 } else
388 first_label = 0;
389
390 if (!(avahi_escape_label((char*) AVAHI_DNS_PACKET_DATA(p) + idx, n, &ret_name, &l)))
391 return -1;
392
393 idx += n;
394
395 if (!compressed)
396 ret += n;
397 } else if ((n & 0xC0) == 0xC0) {
398 /* Compressed label */
399
400 if (idx+2 > p->size)
401 return -1;
402
403 label_ptr = ((unsigned) (AVAHI_DNS_PACKET_DATA(p)[idx] & ~0xC0)) << 8 | AVAHI_DNS_PACKET_DATA(p)[idx+1];
404
405 if ((label_ptr < AVAHI_DNS_PACKET_HEADER_SIZE) || (label_ptr >= idx))
406 return -1;
407
408 idx = label_ptr;
409
410 if (!compressed)
411 ret += 2;
412
413 compressed = 1;
414 } else
415 return -1;
416 }
417
418 return -1;
419 }
420
avahi_dns_packet_consume_name(AvahiDnsPacket * p,char * ret_name,size_t l)421 int avahi_dns_packet_consume_name(AvahiDnsPacket *p, char *ret_name, size_t l) {
422 int r;
423
424 if ((r = consume_labels(p, p->rindex, ret_name, l)) < 0)
425 return -1;
426
427 p->rindex += r;
428 return 0;
429 }
430
avahi_dns_packet_consume_uint16(AvahiDnsPacket * p,uint16_t * ret_v)431 int avahi_dns_packet_consume_uint16(AvahiDnsPacket *p, uint16_t *ret_v) {
432 uint8_t *d;
433
434 assert(p);
435 assert(ret_v);
436
437 if (p->rindex + sizeof(uint16_t) > p->size)
438 return -1;
439
440 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
441 *ret_v = (d[0] << 8) | d[1];
442 p->rindex += sizeof(uint16_t);
443
444 return 0;
445 }
446
avahi_dns_packet_consume_uint32(AvahiDnsPacket * p,uint32_t * ret_v)447 int avahi_dns_packet_consume_uint32(AvahiDnsPacket *p, uint32_t *ret_v) {
448 uint8_t* d;
449
450 assert(p);
451 assert(ret_v);
452
453 if (p->rindex + sizeof(uint32_t) > p->size)
454 return -1;
455
456 d = (uint8_t*) (AVAHI_DNS_PACKET_DATA(p) + p->rindex);
457 *ret_v = (d[0] << 24) | (d[1] << 16) | (d[2] << 8) | d[3];
458 p->rindex += sizeof(uint32_t);
459
460 return 0;
461 }
462
avahi_dns_packet_consume_bytes(AvahiDnsPacket * p,void * ret_data,size_t l)463 int avahi_dns_packet_consume_bytes(AvahiDnsPacket *p, void * ret_data, size_t l) {
464 assert(p);
465 assert(ret_data);
466 assert(l > 0);
467
468 if (p->rindex + l > p->size)
469 return -1;
470
471 memcpy(ret_data, AVAHI_DNS_PACKET_DATA(p) + p->rindex, l);
472 p->rindex += l;
473
474 return 0;
475 }
476
avahi_dns_packet_consume_string(AvahiDnsPacket * p,char * ret_string,size_t l)477 int avahi_dns_packet_consume_string(AvahiDnsPacket *p, char *ret_string, size_t l) {
478 size_t k;
479
480 assert(p);
481 assert(ret_string);
482 assert(l > 0);
483
484 if (p->rindex >= p->size)
485 return -1;
486
487 k = AVAHI_DNS_PACKET_DATA(p)[p->rindex];
488
489 if (p->rindex+1+k > p->size)
490 return -1;
491
492 if (l > k+1)
493 l = k+1;
494
495 memcpy(ret_string, AVAHI_DNS_PACKET_DATA(p)+p->rindex+1, l-1);
496 ret_string[l-1] = 0;
497
498 p->rindex += 1+k;
499
500 return 0;
501 }
502
avahi_dns_packet_get_rptr(AvahiDnsPacket * p)503 const void* avahi_dns_packet_get_rptr(AvahiDnsPacket *p) {
504 assert(p);
505
506 if (p->rindex > p->size)
507 return NULL;
508
509 return AVAHI_DNS_PACKET_DATA(p) + p->rindex;
510 }
511
avahi_dns_packet_skip(AvahiDnsPacket * p,size_t length)512 int avahi_dns_packet_skip(AvahiDnsPacket *p, size_t length) {
513 assert(p);
514
515 if (p->rindex + length > p->size)
516 return -1;
517
518 p->rindex += length;
519 return 0;
520 }
521
parse_rdata(AvahiDnsPacket * p,AvahiRecord * r,uint16_t rdlength)522 static int parse_rdata(AvahiDnsPacket *p, AvahiRecord *r, uint16_t rdlength) {
523 char buf[AVAHI_DOMAIN_NAME_MAX];
524 const void* start;
525
526 assert(p);
527 assert(r);
528
529 start = avahi_dns_packet_get_rptr(p);
530
531 switch (r->key->type) {
532 case AVAHI_DNS_TYPE_PTR:
533 case AVAHI_DNS_TYPE_CNAME:
534 case AVAHI_DNS_TYPE_NS:
535
536 if (avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
537 return -1;
538
539 r->data.ptr.name = avahi_strdup(buf);
540 break;
541
542
543 case AVAHI_DNS_TYPE_SRV:
544
545 if (avahi_dns_packet_consume_uint16(p, &r->data.srv.priority) < 0 ||
546 avahi_dns_packet_consume_uint16(p, &r->data.srv.weight) < 0 ||
547 avahi_dns_packet_consume_uint16(p, &r->data.srv.port) < 0 ||
548 avahi_dns_packet_consume_name(p, buf, sizeof(buf)) < 0)
549 return -1;
550
551 r->data.srv.name = avahi_strdup(buf);
552 break;
553
554 case AVAHI_DNS_TYPE_HINFO:
555
556 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
557 return -1;
558
559 r->data.hinfo.cpu = avahi_strdup(buf);
560
561 if (avahi_dns_packet_consume_string(p, buf, sizeof(buf)) < 0)
562 return -1;
563
564 r->data.hinfo.os = avahi_strdup(buf);
565 break;
566
567 case AVAHI_DNS_TYPE_TXT:
568
569 if (rdlength > 0) {
570 if (avahi_string_list_parse(avahi_dns_packet_get_rptr(p), rdlength, &r->data.txt.string_list) < 0)
571 return -1;
572
573 if (avahi_dns_packet_skip(p, rdlength) < 0)
574 return -1;
575 } else
576 r->data.txt.string_list = NULL;
577
578 break;
579
580 case AVAHI_DNS_TYPE_A:
581
582 /* avahi_log_debug("A"); */
583
584 if (avahi_dns_packet_consume_bytes(p, &r->data.a.address, sizeof(AvahiIPv4Address)) < 0)
585 return -1;
586
587 break;
588
589 case AVAHI_DNS_TYPE_AAAA:
590
591 /* avahi_log_debug("aaaa"); */
592
593 if (avahi_dns_packet_consume_bytes(p, &r->data.aaaa.address, sizeof(AvahiIPv6Address)) < 0)
594 return -1;
595
596 break;
597
598 default:
599
600 /* avahi_log_debug("generic"); */
601
602 if (rdlength > 0) {
603
604 r->data.generic.data = avahi_memdup(avahi_dns_packet_get_rptr(p), rdlength);
605 r->data.generic.size = rdlength;
606
607 if (avahi_dns_packet_skip(p, rdlength) < 0)
608 return -1;
609 }
610
611 break;
612 }
613
614 /* Check if we read enough data */
615 if ((const uint8_t*) avahi_dns_packet_get_rptr(p) - (const uint8_t*) start != rdlength)
616 return -1;
617
618 return 0;
619 }
620
avahi_dns_packet_consume_record(AvahiDnsPacket * p,int * ret_cache_flush)621 AvahiRecord* avahi_dns_packet_consume_record(AvahiDnsPacket *p, int *ret_cache_flush) {
622 char name[AVAHI_DOMAIN_NAME_MAX];
623 uint16_t type, class;
624 uint32_t ttl;
625 uint16_t rdlength;
626 AvahiRecord *r = NULL;
627
628 assert(p);
629
630 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
631 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
632 avahi_dns_packet_consume_uint16(p, &class) < 0 ||
633 avahi_dns_packet_consume_uint32(p, &ttl) < 0 ||
634 avahi_dns_packet_consume_uint16(p, &rdlength) < 0 ||
635 p->rindex + rdlength > p->size)
636 goto fail;
637
638 if (ret_cache_flush)
639 *ret_cache_flush = !!(class & AVAHI_DNS_CACHE_FLUSH);
640 class &= ~AVAHI_DNS_CACHE_FLUSH;
641
642 if (!(r = avahi_record_new_full(name, class, type, ttl)))
643 goto fail;
644
645 if (parse_rdata(p, r, rdlength) < 0)
646 goto fail;
647
648 if (!avahi_record_is_valid(r))
649 goto fail;
650
651 return r;
652
653 fail:
654 if (r)
655 avahi_record_unref(r);
656
657 return NULL;
658 }
659
avahi_dns_packet_consume_key(AvahiDnsPacket * p,int * ret_unicast_response)660 AvahiKey* avahi_dns_packet_consume_key(AvahiDnsPacket *p, int *ret_unicast_response) {
661 char name[256];
662 uint16_t type, class;
663 AvahiKey *k;
664
665 assert(p);
666
667 if (avahi_dns_packet_consume_name(p, name, sizeof(name)) < 0 ||
668 avahi_dns_packet_consume_uint16(p, &type) < 0 ||
669 avahi_dns_packet_consume_uint16(p, &class) < 0)
670 return NULL;
671
672 if (ret_unicast_response)
673 *ret_unicast_response = !!(class & AVAHI_DNS_UNICAST_RESPONSE);
674
675 class &= ~AVAHI_DNS_UNICAST_RESPONSE;
676
677 if (!(k = avahi_key_new(name, class, type)))
678 return NULL;
679
680 if (!avahi_key_is_valid(k)) {
681 avahi_key_unref(k);
682 return NULL;
683 }
684
685 return k;
686 }
687
avahi_dns_packet_append_key(AvahiDnsPacket * p,AvahiKey * k,int unicast_response)688 uint8_t* avahi_dns_packet_append_key(AvahiDnsPacket *p, AvahiKey *k, int unicast_response) {
689 uint8_t *t;
690 size_t size;
691
692 assert(p);
693 assert(k);
694
695 size = p->size;
696
697 if (!(t = avahi_dns_packet_append_name(p, k->name)) ||
698 !avahi_dns_packet_append_uint16(p, k->type) ||
699 !avahi_dns_packet_append_uint16(p, k->clazz | (unicast_response ? AVAHI_DNS_UNICAST_RESPONSE : 0))) {
700 p->size = size;
701 avahi_dns_packet_cleanup_name_table(p);
702
703 return NULL;
704 }
705
706 return t;
707 }
708
append_rdata(AvahiDnsPacket * p,AvahiRecord * r)709 static int append_rdata(AvahiDnsPacket *p, AvahiRecord *r) {
710 assert(p);
711 assert(r);
712
713 switch (r->key->type) {
714
715 case AVAHI_DNS_TYPE_PTR:
716 case AVAHI_DNS_TYPE_CNAME:
717 case AVAHI_DNS_TYPE_NS:
718
719 if (!(avahi_dns_packet_append_name(p, r->data.ptr.name)))
720 return -1;
721
722 break;
723
724 case AVAHI_DNS_TYPE_SRV:
725
726 if (!avahi_dns_packet_append_uint16(p, r->data.srv.priority) ||
727 !avahi_dns_packet_append_uint16(p, r->data.srv.weight) ||
728 !avahi_dns_packet_append_uint16(p, r->data.srv.port) ||
729 !avahi_dns_packet_append_name(p, r->data.srv.name))
730 return -1;
731
732 break;
733
734 case AVAHI_DNS_TYPE_HINFO:
735 if (!avahi_dns_packet_append_string(p, r->data.hinfo.cpu) ||
736 !avahi_dns_packet_append_string(p, r->data.hinfo.os))
737 return -1;
738
739 break;
740
741 case AVAHI_DNS_TYPE_TXT: {
742
743 uint8_t *data;
744 size_t n;
745
746 n = avahi_string_list_serialize(r->data.txt.string_list, NULL, 0);
747
748 if (!(data = avahi_dns_packet_extend(p, n)))
749 return -1;
750
751 avahi_string_list_serialize(r->data.txt.string_list, data, n);
752 break;
753 }
754
755
756 case AVAHI_DNS_TYPE_A:
757
758 if (!avahi_dns_packet_append_bytes(p, &r->data.a.address, sizeof(r->data.a.address)))
759 return -1;
760
761 break;
762
763 case AVAHI_DNS_TYPE_AAAA:
764
765 if (!avahi_dns_packet_append_bytes(p, &r->data.aaaa.address, sizeof(r->data.aaaa.address)))
766 return -1;
767
768 break;
769
770 default:
771
772 if (r->data.generic.size)
773 if (!avahi_dns_packet_append_bytes(p, r->data.generic.data, r->data.generic.size))
774 return -1;
775
776 break;
777 }
778
779 return 0;
780 }
781
782
avahi_dns_packet_append_record(AvahiDnsPacket * p,AvahiRecord * r,int cache_flush,unsigned max_ttl)783 uint8_t* avahi_dns_packet_append_record(AvahiDnsPacket *p, AvahiRecord *r, int cache_flush, unsigned max_ttl) {
784 uint8_t *t, *l, *start;
785 size_t size;
786
787 assert(p);
788 assert(r);
789
790 size = p->size;
791
792 if (!(t = avahi_dns_packet_append_name(p, r->key->name)) ||
793 !avahi_dns_packet_append_uint16(p, r->key->type) ||
794 !avahi_dns_packet_append_uint16(p, cache_flush ? (r->key->clazz | AVAHI_DNS_CACHE_FLUSH) : (r->key->clazz &~ AVAHI_DNS_CACHE_FLUSH)) ||
795 !avahi_dns_packet_append_uint32(p, (max_ttl && r->ttl > max_ttl) ? max_ttl : r->ttl) ||
796 !(l = avahi_dns_packet_append_uint16(p, 0)))
797 goto fail;
798
799 start = avahi_dns_packet_extend(p, 0);
800
801 if (append_rdata(p, r) < 0)
802 goto fail;
803
804 size = avahi_dns_packet_extend(p, 0) - start;
805 assert(size <= AVAHI_DNS_RDATA_MAX);
806
807 /* avahi_log_debug("appended %u", size); */
808
809 l[0] = (uint8_t) ((uint16_t) size >> 8);
810 l[1] = (uint8_t) ((uint16_t) size);
811
812 return t;
813
814
815 fail:
816 p->size = size;
817 avahi_dns_packet_cleanup_name_table(p);
818
819 return NULL;
820 }
821
avahi_dns_packet_is_empty(AvahiDnsPacket * p)822 int avahi_dns_packet_is_empty(AvahiDnsPacket *p) {
823 assert(p);
824
825 return p->size <= AVAHI_DNS_PACKET_HEADER_SIZE;
826 }
827
avahi_dns_packet_space(AvahiDnsPacket * p)828 size_t avahi_dns_packet_space(AvahiDnsPacket *p) {
829 assert(p);
830
831 assert(p->size <= p->max_size);
832
833 return p->max_size - p->size;
834 }
835
avahi_rdata_parse(AvahiRecord * record,const void * rdata,size_t size)836 int avahi_rdata_parse(AvahiRecord *record, const void* rdata, size_t size) {
837 int ret;
838 AvahiDnsPacket p;
839
840 assert(record);
841 assert(rdata);
842
843 p.data = (void*) rdata;
844 p.max_size = p.size = size;
845 p.rindex = 0;
846 p.name_table = NULL;
847
848 ret = parse_rdata(&p, record, size);
849
850 assert(!p.name_table);
851
852 return ret;
853 }
854
avahi_rdata_serialize(AvahiRecord * record,void * rdata,size_t max_size)855 size_t avahi_rdata_serialize(AvahiRecord *record, void *rdata, size_t max_size) {
856 int ret;
857 AvahiDnsPacket p;
858
859 assert(record);
860 assert(rdata);
861 assert(max_size > 0);
862
863 p.data = (void*) rdata;
864 p.max_size = max_size;
865 p.size = p.rindex = 0;
866 p.name_table = NULL;
867
868 ret = append_rdata(&p, record);
869
870 if (p.name_table)
871 avahi_hashmap_free(p.name_table);
872
873 if (ret < 0)
874 return (size_t) -1;
875
876 return p.size;
877 }
878