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74b2466e
LP		 1/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
2
3/***
4 This file is part of systemd.
5
6 Copyright 2014 Lennart Poettering
7
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
12
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
17
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
20 ***/
21
b5efdb8a 22#include "alloc-util.h"
4ad7f276 23#include "dns-domain.h"
74b2466e 24#include "resolved-dns-packet.h"
8b43440b
LP		 25#include "string-table.h"
26#include "strv.h"
27#include "unaligned.h"
28#include "utf8.h"
29#include "util.h"
74b2466e 30
7586f4d1
TG		 31#define EDNS0_OPT_DO (1<<15)
32
1716f6dc 33int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
74b2466e
LP		 34 DnsPacket *p;
35 size_t a;
36
37 assert(ret);
38
a0166609 39 if (mtu <= UDP_PACKET_HEADER_SIZE)
74b2466e
LP		 40 a = DNS_PACKET_SIZE_START;
41 else
a0166609 42 a = mtu - UDP_PACKET_HEADER_SIZE;
74b2466e
LP		 43
44 if (a < DNS_PACKET_HEADER_SIZE)
45 a = DNS_PACKET_HEADER_SIZE;
46
c73ce96b
LP		 47 /* round up to next page size */
48 a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));
49
50 /* make sure we never allocate more than useful */
51 if (a > DNS_PACKET_SIZE_MAX)
52 a = DNS_PACKET_SIZE_MAX;
53
74b2466e
LP		 54 p = malloc0(ALIGN(sizeof(DnsPacket)) + a);
55 if (!p)
56 return -ENOMEM;
57
58 p->size = p->rindex = DNS_PACKET_HEADER_SIZE;
59 p->allocated = a;
1716f6dc 60 p->protocol = protocol;
519ef046 61 p->opt_start = p->opt_size = (size_t) -1;
74b2466e
LP		 62 p->n_ref = 1;
63
64 *ret = p;
65
66 return 0;
67}
68
dbfbb6e7 69void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated) {
74b2466e 70
dbfbb6e7 71 DnsPacketHeader *h;
74b2466e 72
dbfbb6e7 73 assert(p);
74b2466e
LP		 74
75 h = DNS_PACKET_HEADER(p);
1716f6dc 76
dbfbb6e7
DM		 77 switch(p->protocol) {
78 case DNS_PROTOCOL_LLMNR:
79 assert(!truncated);
80
069360a6
LP		 81 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
82 0 /* opcode */,
83 0 /* c */,
e5abebab 84 0 /* tc */,
069360a6
LP		 85 0 /* t */,
86 0 /* ra */,
87 0 /* ad */,
88 0 /* cd */,
89 0 /* rcode */));
dbfbb6e7
DM		 90 break;
91
92 case DNS_PROTOCOL_MDNS:
93 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
94 0 /* opcode */,
95 0 /* aa */,
96 truncated /* tc */,
97 0 /* rd (ask for recursion) */,
98 0 /* ra */,
99 0 /* ad */,
100 0 /* cd */,
101 0 /* rcode */));
102 break;
103
104 default:
105 assert(!truncated);
106
069360a6
LP		 107 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
108 0 /* opcode */,
109 0 /* aa */,
110 0 /* tc */,
111 1 /* rd (ask for recursion) */,
112 0 /* ra */,
113 0 /* ad */,
24710c48 114 dnssec_checking_disabled /* cd */,
069360a6 115 0 /* rcode */));
dbfbb6e7
DM		 116 }
117}
118
119int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled) {
120 DnsPacket *p;
121 int r;
122
123 assert(ret);
124
125 r = dns_packet_new(&p, protocol, mtu);
126 if (r < 0)
127 return r;
128
129 /* Always set the TC bit to 0 initially.
130 * If there are multiple packets later, we'll update the bit shortly before sending.
131 */
132 dns_packet_set_flags(p, dnssec_checking_disabled, false);
74b2466e
LP		 133
134 *ret = p;
135 return 0;
136}
137
138DnsPacket *dns_packet_ref(DnsPacket *p) {
139
140 if (!p)
141 return NULL;
142
a8812dd7
LP		 143 assert(!p->on_stack);
144
74b2466e
LP		 145 assert(p->n_ref > 0);
146 p->n_ref++;
147 return p;
148}
149
150static void dns_packet_free(DnsPacket *p) {
151 char *s;
152
153 assert(p);
154
faa133f3
LP		 155 dns_question_unref(p->question);
156 dns_answer_unref(p->answer);
d75acfb0 157 dns_resource_record_unref(p->opt);
322345fd 158
74b2466e
LP		 159 while ((s = hashmap_steal_first_key(p->names)))
160 free(s);
161 hashmap_free(p->names);
162
faa133f3 163 free(p->_data);
a8812dd7
LP		 164
165 if (!p->on_stack)
166 free(p);
74b2466e
LP		 167}
168
169DnsPacket *dns_packet_unref(DnsPacket *p) {
170 if (!p)
171 return NULL;
172
173 assert(p->n_ref > 0);
174
6728a58d 175 dns_packet_unref(p->more);
9c491563 176
74b2466e
LP		 177 if (p->n_ref == 1)
178 dns_packet_free(p);
179 else
180 p->n_ref--;
181
182 return NULL;
183}
184
185int dns_packet_validate(DnsPacket *p) {
186 assert(p);
187
188 if (p->size < DNS_PACKET_HEADER_SIZE)
189 return -EBADMSG;
190
c73ce96b
LP		 191 if (p->size > DNS_PACKET_SIZE_MAX)
192 return -EBADMSG;
193
623a4c97 194 return 1;
74b2466e
LP		 195}
196
197int dns_packet_validate_reply(DnsPacket *p) {
74b2466e
LP		 198 int r;
199
200 assert(p);
201
202 r = dns_packet_validate(p);
203 if (r < 0)
204 return r;
205
623a4c97
LP		 206 if (DNS_PACKET_QR(p) != 1)
207 return 0;
208
209 if (DNS_PACKET_OPCODE(p) != 0)
74b2466e
LP		 210 return -EBADMSG;
211
818ef443 212 switch (p->protocol) {
d75acfb0 213
818ef443
DM		 214 case DNS_PROTOCOL_LLMNR:
215 /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
216 if (DNS_PACKET_QDCOUNT(p) != 1)
217 return -EBADMSG;
218
219 break;
220
4e5bf5e1
DM		 221 case DNS_PROTOCOL_MDNS:
222 /* RFC 6762, Section 18 */
223 if (DNS_PACKET_RCODE(p) != 0)
224 return -EBADMSG;
225
226 break;
227
818ef443
DM		 228 default:
229 break;
230 }
ea917db9 231
623a4c97
LP		 232 return 1;
233}
234
235int dns_packet_validate_query(DnsPacket *p) {
236 int r;
237
238 assert(p);
239
240 r = dns_packet_validate(p);
241 if (r < 0)
242 return r;
243
244 if (DNS_PACKET_QR(p) != 0)
245 return 0;
246
3cb10d3a 247 if (DNS_PACKET_OPCODE(p) != 0)
74b2466e
LP		 248 return -EBADMSG;
249
623a4c97
LP		 250 if (DNS_PACKET_TC(p))
251 return -EBADMSG;
252
818ef443 253 switch (p->protocol) {
d75acfb0 254
818ef443
DM		 255 case DNS_PROTOCOL_LLMNR:
256 /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
257 if (DNS_PACKET_QDCOUNT(p) != 1)
258 return -EBADMSG;
623a4c97 259
818ef443
DM		 260 /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
261 if (DNS_PACKET_ANCOUNT(p) > 0)
262 return -EBADMSG;
623a4c97 263
818ef443
DM		 264 /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
265 if (DNS_PACKET_NSCOUNT(p) > 0)
266 return -EBADMSG;
267
268 break;
269
4e5bf5e1
DM		 270 case DNS_PROTOCOL_MDNS:
271 /* RFC 6762, Section 18 */
272 if (DNS_PACKET_AA(p) != 0 ||
273 DNS_PACKET_RD(p) != 0 ||
274 DNS_PACKET_RA(p) != 0 ||
275 DNS_PACKET_AD(p) != 0 ||
276 DNS_PACKET_CD(p) != 0 ||
277 DNS_PACKET_RCODE(p) != 0)
278 return -EBADMSG;
279
280 break;
281
818ef443
DM		 282 default:
283 break;
284 }
623a4c97
LP		 285
286 return 1;
74b2466e
LP		 287}
288
289static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) {
290 assert(p);
291
c73ce96b
LP		 292 if (p->size + add > p->allocated) {
293 size_t a;
294
295 a = PAGE_ALIGN((p->size + add) * 2);
296 if (a > DNS_PACKET_SIZE_MAX)
297 a = DNS_PACKET_SIZE_MAX;
298
299 if (p->size + add > a)
300 return -EMSGSIZE;
301
faa133f3 302 if (p->_data) {
c73ce96b
LP		 303 void *d;
304
faa133f3 305 d = realloc(p->_data, a);
c73ce96b
LP		 306 if (!d)
307 return -ENOMEM;
308
faa133f3 309 p->_data = d;
c73ce96b 310 } else {
faa133f3
LP		 311 p->_data = malloc(a);
312 if (!p->_data)
c73ce96b
LP		 313 return -ENOMEM;
314
faa133f3
LP		 315 memcpy(p->_data, (uint8_t*) p + ALIGN(sizeof(DnsPacket)), p->size);
316 memzero((uint8_t*) p->_data + p->size, a - p->size);
c73ce96b
LP		 317 }
318
319 p->allocated = a;
320 }
74b2466e
LP		 321
322 if (start)
323 *start = p->size;
324
325 if (ret)
326 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->size;
327
328 p->size += add;
329 return 0;
330}
331
9c5e12a4 332void dns_packet_truncate(DnsPacket *p, size_t sz) {
74b2466e
LP		 333 Iterator i;
334 char *s;
335 void *n;
336
337 assert(p);
338
339 if (p->size <= sz)
340 return;
341
0e03ade5 342 HASHMAP_FOREACH_KEY(n, s, p->names, i) {
74b2466e
LP		 343
344 if (PTR_TO_SIZE(n) < sz)
345 continue;
346
347 hashmap_remove(p->names, s);
348 free(s);
349 }
350
351 p->size = sz;
352}
353
623a4c97
LP		 354int dns_packet_append_blob(DnsPacket *p, const void *d, size_t l, size_t *start) {
355 void *q;
356 int r;
357
358 assert(p);
359
360 r = dns_packet_extend(p, l, &q, start);
361 if (r < 0)
362 return r;
363
364 memcpy(q, d, l);
365 return 0;
366}
367
74b2466e
LP		 368int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start) {
369 void *d;
370 int r;
371
372 assert(p);
373
374 r = dns_packet_extend(p, sizeof(uint8_t), &d, start);
375 if (r < 0)
376 return r;
377
378 ((uint8_t*) d)[0] = v;
379
380 return 0;
381}
382
383int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) {
384 void *d;
385 int r;
386
387 assert(p);
388
389 r = dns_packet_extend(p, sizeof(uint16_t), &d, start);
390 if (r < 0)
391 return r;
392
725ca0e5 393 unaligned_write_be16(d, v);
623a4c97
LP		 394
395 return 0;
396}
397
398int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
399 void *d;
400 int r;
401
402 assert(p);
403
404 r = dns_packet_extend(p, sizeof(uint32_t), &d, start);
405 if (r < 0)
406 return r;
407
725ca0e5 408 unaligned_write_be32(d, v);
74b2466e
LP		 409
410 return 0;
411}
412
413int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) {
74b2466e
LP		 414 assert(p);
415 assert(s);
416
c38a52da 417 return dns_packet_append_raw_string(p, s, strlen(s), start);
74b2466e
LP		 418}
419
2001c805
LP		 420int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start) {
421 void *d;
422 int r;
423
424 assert(p);
425 assert(s || size == 0);
426
427 if (size > 255)
428 return -E2BIG;
429
430 r = dns_packet_extend(p, 1 + size, &d, start);
431 if (r < 0)
432 return r;
433
434 ((uint8_t*) d)[0] = (uint8_t) size;
435
436 if (size > 0)
437 memcpy(((uint8_t*) d) + 1, s, size);
438
439 return 0;
440}
441
a3db237b 442int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, bool canonical_candidate, size_t *start) {
a8812dd7 443 uint8_t *w;
74b2466e
LP		 444 int r;
445
a3db237b
LP		 446 /* Append a label to a packet. Optionally, does this in DNSSEC
447 * canonical form, if this label is marked as a candidate for
448 * it, and the canonical form logic is enabled for the
449 * packet */
450
74b2466e
LP		 451 assert(p);
452 assert(d);
453
454 if (l > DNS_LABEL_MAX)
455 return -E2BIG;
456
a8812dd7 457 r = dns_packet_extend(p, 1 + l, (void**) &w, start);
74b2466e
LP		 458 if (r < 0)
459 return r;
460
a8812dd7
LP		 461 *(w++) = (uint8_t) l;
462
a3db237b 463 if (p->canonical_form && canonical_candidate) {
a8812dd7
LP		 464 size_t i;
465
466 /* Generate in canonical form, as defined by DNSSEC
467 * RFC 4034, Section 6.2, i.e. all lower-case. */
468
b577e3d5
LP		 469 for (i = 0; i < l; i++)
470 w[i] = (uint8_t) ascii_tolower(d[i]);
a8812dd7
LP		 471 } else
472 /* Otherwise, just copy the string unaltered. This is
473 * essential for DNS-SD, where the casing of labels
474 * matters and needs to be retained. */
475 memcpy(w, d, l);
74b2466e
LP		 476
477 return 0;
478}
479
f6a5fec6
LP		 480int dns_packet_append_name(
481 DnsPacket *p,
482 const char *name,
483 bool allow_compression,
a3db237b 484 bool canonical_candidate,
f6a5fec6
LP		 485 size_t *start) {
486
74b2466e
LP		 487 size_t saved_size;
488 int r;
489
490 assert(p);
491 assert(name);
492
f6a5fec6
LP		 493 if (p->refuse_compression)
494 allow_compression = false;
495
74b2466e
LP		 496 saved_size = p->size;
497
e48b9a64 498 while (!dns_name_is_root(name)) {
08f904fd 499 const char *z = name;
74b2466e 500 char label[DNS_LABEL_MAX];
151226ab 501 size_t n = 0;
74b2466e 502
151226ab
ZJS		 503 if (allow_compression)
504 n = PTR_TO_SIZE(hashmap_get(p->names, name));
74b2466e
LP		 505 if (n > 0) {
506 assert(n < p->size);
507
508 if (n < 0x4000) {
509 r = dns_packet_append_uint16(p, 0xC000 | n, NULL);
510 if (r < 0)
511 goto fail;
512
513 goto done;
514 }
515 }
516
74b2466e
LP		 517 r = dns_label_unescape(&name, label, sizeof(label));
518 if (r < 0)
519 goto fail;
520
a3db237b 521 r = dns_packet_append_label(p, label, r, canonical_candidate, &n);
74b2466e
LP		 522 if (r < 0)
523 goto fail;
524
151226ab 525 if (allow_compression) {
08f904fd
LP		 526 _cleanup_free_ char *s = NULL;
527
528 s = strdup(z);
529 if (!s) {
530 r = -ENOMEM;
531 goto fail;
532 }
533
d5099efc 534 r = hashmap_ensure_allocated(&p->names, &dns_name_hash_ops);
151226ab
ZJS		 535 if (r < 0)
536 goto fail;
74b2466e 537
151226ab
ZJS		 538 r = hashmap_put(p->names, s, SIZE_TO_PTR(n));
539 if (r < 0)
540 goto fail;
74b2466e 541
151226ab
ZJS		 542 s = NULL;
543 }
74b2466e
LP		 544 }
545
546 r = dns_packet_append_uint8(p, 0, NULL);
547 if (r < 0)
548 return r;
549
550done:
551 if (start)
552 *start = saved_size;
553
554 return 0;
555
556fail:
557 dns_packet_truncate(p, saved_size);
558 return r;
559}
560
561int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start) {
562 size_t saved_size;
563 int r;
564
565 assert(p);
566 assert(k);
567
568 saved_size = p->size;
569
a3db237b 570 r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), true, true, NULL);
74b2466e
LP		 571 if (r < 0)
572 goto fail;
573
574 r = dns_packet_append_uint16(p, k->type, NULL);
575 if (r < 0)
576 goto fail;
577
578 r = dns_packet_append_uint16(p, k->class, NULL);
579 if (r < 0)
580 goto fail;
581
582 if (start)
583 *start = saved_size;
584
585 return 0;
586
587fail:
588 dns_packet_truncate(p, saved_size);
589 return r;
590}
591
e1a9f1a8 592static int dns_packet_append_type_window(DnsPacket *p, uint8_t window, uint8_t length, const uint8_t *types, size_t *start) {
50f1e641
TG		 593 size_t saved_size;
594 int r;
595
596 assert(p);
597 assert(types);
1792f223 598 assert(length > 0);
50f1e641 599
50f1e641
TG		 600 saved_size = p->size;
601
1792f223
TG		 602 r = dns_packet_append_uint8(p, window, NULL);
603 if (r < 0)
604 goto fail;
50f1e641 605
1792f223
TG		 606 r = dns_packet_append_uint8(p, length, NULL);
607 if (r < 0)
608 goto fail;
6fa91901 609
1792f223
TG		 610 r = dns_packet_append_blob(p, types, length, NULL);
611 if (r < 0)
612 goto fail;
50f1e641
TG		 613
614 if (start)
615 *start = saved_size;
616
617 return 0;
618fail:
619 dns_packet_truncate(p, saved_size);
620 return r;
621}
622
623static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) {
cb57dd41 624 Iterator i;
50f1e641 625 uint8_t window = 0;
1792f223 626 uint8_t entry = 0;
50f1e641
TG		 627 uint8_t bitmaps[32] = {};
628 unsigned n;
629 size_t saved_size;
630 int r;
631
632 assert(p);
50f1e641
TG		 633
634 saved_size = p->size;
635
cb57dd41 636 BITMAP_FOREACH(n, types, i) {
50f1e641
TG		 637 assert(n <= 0xffff);
638
1792f223
TG		 639 if ((n >> 8) != window && bitmaps[entry / 8] != 0) {
640 r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
50f1e641
TG		 641 if (r < 0)
642 goto fail;
643
1792f223 644 zero(bitmaps);
50f1e641
TG		 645 }
646
1792f223 647 window = n >> 8;
50f1e641
TG		 648 entry = n & 255;
649
650 bitmaps[entry / 8] |= 1 << (7 - (entry % 8));
651 }
652
d0ae14ff
LP		 653 if (bitmaps[entry / 8] != 0) {
654 r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
655 if (r < 0)
656 goto fail;
657 }
50f1e641
TG		 658
659 if (start)
660 *start = saved_size;
661
662 return 0;
663fail:
664 dns_packet_truncate(p, saved_size);
665 return r;
666}
667
dc913c9a 668/* Append the OPT pseudo-RR described in RFC6891 */
519ef046 669int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start) {
dc913c9a
TG		 670 size_t saved_size;
671 int r;
672
673 assert(p);
674 /* we must never advertise supported packet size smaller than the legacy max */
675 assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX);
676
519ef046
LP		 677 if (p->opt_start != (size_t) -1)
678 return -EBUSY;
679
680 assert(p->opt_size == (size_t) -1);
681
dc913c9a
TG		 682 saved_size = p->size;
683
684 /* empty name */
685 r = dns_packet_append_uint8(p, 0, NULL);
686 if (r < 0)
687 return r;
688
689 /* type */
690 r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL);
691 if (r < 0)
692 goto fail;
693
694 /* maximum udp packet that can be received */
695 r = dns_packet_append_uint16(p, max_udp_size, NULL);
696 if (r < 0)
697 goto fail;
698
699 /* extended RCODE and VERSION */
700 r = dns_packet_append_uint16(p, 0, NULL);
701 if (r < 0)
702 goto fail;
703
7586f4d1
TG		 704 /* flags: DNSSEC OK (DO), see RFC3225 */
705 r = dns_packet_append_uint16(p, edns0_do ? EDNS0_OPT_DO : 0, NULL);
dc913c9a
TG		 706 if (r < 0)
707 goto fail;
708
709 /* RDLENGTH */
665408ac
LP		 710
711 if (edns0_do) {
712 /* If DO is on, also append RFC6975 Algorithm data */
713
714 static const uint8_t rfc6975[] = {
715
716 0, 5, /* OPTION_CODE: DAU */
717 0, 6, /* LIST_LENGTH */
718 DNSSEC_ALGORITHM_RSASHA1,
719 DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
720 DNSSEC_ALGORITHM_RSASHA256,
721 DNSSEC_ALGORITHM_RSASHA512,
722 DNSSEC_ALGORITHM_ECDSAP256SHA256,
723 DNSSEC_ALGORITHM_ECDSAP384SHA384,
724
725 0, 6, /* OPTION_CODE: DHU */
726 0, 3, /* LIST_LENGTH */
727 DNSSEC_DIGEST_SHA1,
728 DNSSEC_DIGEST_SHA256,
729 DNSSEC_DIGEST_SHA384,
730
731 0, 7, /* OPTION_CODE: N3U */
732 0, 1, /* LIST_LENGTH */
733 NSEC3_ALGORITHM_SHA1,
734 };
735
736 r = dns_packet_append_uint16(p, sizeof(rfc6975), NULL);
737 if (r < 0)
738 goto fail;
739
740 r = dns_packet_append_blob(p, rfc6975, sizeof(rfc6975), NULL);
741 } else
742 r = dns_packet_append_uint16(p, 0, NULL);
743
dc913c9a
TG		 744 if (r < 0)
745 goto fail;
746
519ef046
LP		 747 DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) + 1);
748
749 p->opt_start = saved_size;
750 p->opt_size = p->size - saved_size;
751
dc913c9a
TG		 752 if (start)
753 *start = saved_size;
754
755 return 0;
756
757fail:
758 dns_packet_truncate(p, saved_size);
759 return r;
760}
761
519ef046
LP		 762int dns_packet_truncate_opt(DnsPacket *p) {
763 assert(p);
764
765 if (p->opt_start == (size_t) -1) {
766 assert(p->opt_size == (size_t) -1);
767 return 0;
768 }
769
770 assert(p->opt_size != (size_t) -1);
771 assert(DNS_PACKET_ARCOUNT(p) > 0);
772
773 if (p->opt_start + p->opt_size != p->size)
774 return -EBUSY;
775
776 dns_packet_truncate(p, p->opt_start);
777 DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) - 1);
778 p->opt_start = p->opt_size = (size_t) -1;
779
780 return 1;
781}
782
a8812dd7
LP		 783int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start) {
784 size_t saved_size, rdlength_offset, end, rdlength, rds;
623a4c97
LP		 785 int r;
786
787 assert(p);
788 assert(rr);
789
790 saved_size = p->size;
791
792 r = dns_packet_append_key(p, rr->key, NULL);
793 if (r < 0)
794 goto fail;
795
796 r = dns_packet_append_uint32(p, rr->ttl, NULL);
797 if (r < 0)
798 goto fail;
799
800 /* Initially we write 0 here */
801 r = dns_packet_append_uint16(p, 0, &rdlength_offset);
802 if (r < 0)
803 goto fail;
804
a8812dd7
LP		 805 rds = p->size - saved_size;
806
0dae31d4 807 switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
623a4c97 808
9c92ce6d
LP		 809 case DNS_TYPE_SRV:
810 r = dns_packet_append_uint16(p, rr->srv.priority, NULL);
811 if (r < 0)
812 goto fail;
813
814 r = dns_packet_append_uint16(p, rr->srv.weight, NULL);
815 if (r < 0)
816 goto fail;
817
818 r = dns_packet_append_uint16(p, rr->srv.port, NULL);
819 if (r < 0)
820 goto fail;
821
a3db237b 822 r = dns_packet_append_name(p, rr->srv.name, true, false, NULL);
9c92ce6d
LP		 823 break;
824
623a4c97
LP		 825 case DNS_TYPE_PTR:
826 case DNS_TYPE_NS:
827 case DNS_TYPE_CNAME:
8ac4e9e1 828 case DNS_TYPE_DNAME:
a3db237b 829 r = dns_packet_append_name(p, rr->ptr.name, true, false, NULL);
623a4c97
LP		 830 break;
831
832 case DNS_TYPE_HINFO:
833 r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
834 if (r < 0)
835 goto fail;
836
837 r = dns_packet_append_string(p, rr->hinfo.os, NULL);
838 break;
839
9de3e329 840 case DNS_TYPE_SPF: /* exactly the same as TXT */
2001c805 841 case DNS_TYPE_TXT:
2e276efc 842
2001c805 843 if (!rr->txt.items) {
1ccda9b7
LP		 844 /* RFC 6763, section 6.1 suggests to generate
845 * single empty string for an empty array. */
846
2001c805 847 r = dns_packet_append_raw_string(p, NULL, 0, NULL);
2e276efc
ZJS		 848 if (r < 0)
849 goto fail;
1ccda9b7 850 } else {
2001c805
LP		 851 DnsTxtItem *i;
852
853 LIST_FOREACH(items, i, rr->txt.items) {
854 r = dns_packet_append_raw_string(p, i->data, i->length, NULL);
1ccda9b7
LP		 855 if (r < 0)
856 goto fail;
857 }
2e276efc
ZJS		 858 }
859
6a6fc3df 860 r = 0;
2e276efc 861 break;
2e276efc 862
623a4c97
LP		 863 case DNS_TYPE_A:
864 r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
865 break;
866
867 case DNS_TYPE_AAAA:
868 r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
869 break;
870
871 case DNS_TYPE_SOA:
a3db237b 872 r = dns_packet_append_name(p, rr->soa.mname, true, false, NULL);
623a4c97
LP		 873 if (r < 0)
874 goto fail;
875
a3db237b 876 r = dns_packet_append_name(p, rr->soa.rname, true, false, NULL);
623a4c97
LP		 877 if (r < 0)
878 goto fail;
879
880 r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
881 if (r < 0)
882 goto fail;
883
884 r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
885 if (r < 0)
886 goto fail;
887
888 r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
889 if (r < 0)
890 goto fail;
891
892 r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
893 if (r < 0)
894 goto fail;
895
896 r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
897 break;
898
899 case DNS_TYPE_MX:
946c7094
ZJS		 900 r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
901 if (r < 0)
902 goto fail;
903
a3db237b 904 r = dns_packet_append_name(p, rr->mx.exchange, true, false, NULL);
946c7094
ZJS		 905 break;
906
0dae31d4
ZJS		 907 case DNS_TYPE_LOC:
908 r = dns_packet_append_uint8(p, rr->loc.version, NULL);
909 if (r < 0)
910 goto fail;
911
912 r = dns_packet_append_uint8(p, rr->loc.size, NULL);
913 if (r < 0)
914 goto fail;
915
916 r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL);
917 if (r < 0)
918 goto fail;
919
920 r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL);
921 if (r < 0)
922 goto fail;
923
afbc4f26 924 r = dns_packet_append_uint32(p, rr->loc.latitude, NULL);
0dae31d4
ZJS		 925 if (r < 0)
926 goto fail;
927
afbc4f26 928 r = dns_packet_append_uint32(p, rr->loc.longitude, NULL);
0dae31d4
ZJS		 929 if (r < 0)
930 goto fail;
931
afbc4f26 932 r = dns_packet_append_uint32(p, rr->loc.altitude, NULL);
0dae31d4
ZJS		 933 break;
934
abf126a3
TG		 935 case DNS_TYPE_DS:
936 r = dns_packet_append_uint16(p, rr->ds.key_tag, NULL);
937 if (r < 0)
938 goto fail;
939
940 r = dns_packet_append_uint8(p, rr->ds.algorithm, NULL);
941 if (r < 0)
942 goto fail;
943
944 r = dns_packet_append_uint8(p, rr->ds.digest_type, NULL);
945 if (r < 0)
946 goto fail;
947
948 r = dns_packet_append_blob(p, rr->ds.digest, rr->ds.digest_size, NULL);
949 break;
950
623a4c97 951 case DNS_TYPE_SSHFP:
42cc2eeb
LP		 952 r = dns_packet_append_uint8(p, rr->sshfp.algorithm, NULL);
953 if (r < 0)
954 goto fail;
8db0d2f5 955
42cc2eeb
LP		 956 r = dns_packet_append_uint8(p, rr->sshfp.fptype, NULL);
957 if (r < 0)
958 goto fail;
959
549c1a25 960 r = dns_packet_append_blob(p, rr->sshfp.fingerprint, rr->sshfp.fingerprint_size, NULL);
42cc2eeb
LP		 961 break;
962
8db0d2f5 963 case DNS_TYPE_DNSKEY:
f91dc240 964 r = dns_packet_append_uint16(p, rr->dnskey.flags, NULL);
8db0d2f5
ZJS		 965 if (r < 0)
966 goto fail;
967
f91dc240 968 r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL);
8db0d2f5
ZJS		 969 if (r < 0)
970 goto fail;
971
972 r = dns_packet_append_uint8(p, rr->dnskey.algorithm, NULL);
973 if (r < 0)
974 goto fail;
975
976 r = dns_packet_append_blob(p, rr->dnskey.key, rr->dnskey.key_size, NULL);
977 break;
978
151226ab
ZJS		 979 case DNS_TYPE_RRSIG:
980 r = dns_packet_append_uint16(p, rr->rrsig.type_covered, NULL);
981 if (r < 0)
982 goto fail;
983
984 r = dns_packet_append_uint8(p, rr->rrsig.algorithm, NULL);
985 if (r < 0)
986 goto fail;
987
988 r = dns_packet_append_uint8(p, rr->rrsig.labels, NULL);
989 if (r < 0)
990 goto fail;
991
992 r = dns_packet_append_uint32(p, rr->rrsig.original_ttl, NULL);
993 if (r < 0)
994 goto fail;
995
996 r = dns_packet_append_uint32(p, rr->rrsig.expiration, NULL);
997 if (r < 0)
998 goto fail;
999
1000 r = dns_packet_append_uint32(p, rr->rrsig.inception, NULL);
1001 if (r < 0)
1002 goto fail;
1003
0b1b17d3 1004 r = dns_packet_append_uint16(p, rr->rrsig.key_tag, NULL);
151226ab
ZJS		 1005 if (r < 0)
1006 goto fail;
1007
a3db237b 1008 r = dns_packet_append_name(p, rr->rrsig.signer, false, true, NULL);
151226ab
ZJS		 1009 if (r < 0)
1010 goto fail;
1011
1012 r = dns_packet_append_blob(p, rr->rrsig.signature, rr->rrsig.signature_size, NULL);
1013 break;
1014
50f1e641 1015 case DNS_TYPE_NSEC:
a3db237b 1016 r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, false, NULL);
50f1e641
TG		 1017 if (r < 0)
1018 goto fail;
1019
1020 r = dns_packet_append_types(p, rr->nsec.types, NULL);
1021 if (r < 0)
1022 goto fail;
1023
5d45a880 1024 break;
d75acfb0 1025
5d45a880
TG		 1026 case DNS_TYPE_NSEC3:
1027 r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL);
1028 if (r < 0)
1029 goto fail;
1030
1031 r = dns_packet_append_uint8(p, rr->nsec3.flags, NULL);
1032 if (r < 0)
1033 goto fail;
1034
1035 r = dns_packet_append_uint16(p, rr->nsec3.iterations, NULL);
1036 if (r < 0)
1037 goto fail;
1038
1039 r = dns_packet_append_uint8(p, rr->nsec3.salt_size, NULL);
1040 if (r < 0)
1041 goto fail;
1042
1043 r = dns_packet_append_blob(p, rr->nsec3.salt, rr->nsec3.salt_size, NULL);
1044 if (r < 0)
1045 goto fail;
1046
1047 r = dns_packet_append_uint8(p, rr->nsec3.next_hashed_name_size, NULL);
1048 if (r < 0)
1049 goto fail;
1050
1051 r = dns_packet_append_blob(p, rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, NULL);
1052 if (r < 0)
1053 goto fail;
1054
1055 r = dns_packet_append_types(p, rr->nsec3.types, NULL);
1056 if (r < 0)
1057 goto fail;
1058
50f1e641 1059 break;
d75acfb0 1060
48d45d2b
ZJS		 1061 case DNS_TYPE_TLSA:
1062 r = dns_packet_append_uint8(p, rr->tlsa.cert_usage, NULL);
1063 if (r < 0)
1064 goto fail;
1065
1066 r = dns_packet_append_uint8(p, rr->tlsa.selector, NULL);
1067 if (r < 0)
1068 goto fail;
1069
1070 r = dns_packet_append_uint8(p, rr->tlsa.matching_type, NULL);
1071 if (r < 0)
1072 goto fail;
1073
1074 r = dns_packet_append_blob(p, rr->tlsa.data, rr->tlsa.data_size, NULL);
1075 break;
1076
d75acfb0 1077 case DNS_TYPE_OPT:
0dae31d4 1078 case _DNS_TYPE_INVALID: /* unparseable */
623a4c97 1079 default:
0dae31d4 1080
623a4c97
LP		 1081 r = dns_packet_append_blob(p, rr->generic.data, rr->generic.size, NULL);
1082 break;
1083 }
1084 if (r < 0)
1085 goto fail;
1086
1087 /* Let's calculate the actual data size and update the field */
1088 rdlength = p->size - rdlength_offset - sizeof(uint16_t);
1089 if (rdlength > 0xFFFF) {
555f5cdc 1090 r = -ENOSPC;
623a4c97
LP		 1091 goto fail;
1092 }
1093
1094 end = p->size;
1095 p->size = rdlength_offset;
1096 r = dns_packet_append_uint16(p, rdlength, NULL);
1097 if (r < 0)
1098 goto fail;
1099 p->size = end;
1100
351e6342
LP		 1101 if (start)
1102 *start = saved_size;
1103
a8812dd7
LP		 1104 if (rdata_start)
1105 *rdata_start = rds;
1106
623a4c97
LP		 1107 return 0;
1108
1109fail:
1110 dns_packet_truncate(p, saved_size);
1111 return r;
1112}
1113
74b2466e
LP		 1114int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
1115 assert(p);
1116
1117 if (p->rindex + sz > p->size)
1118 return -EMSGSIZE;
1119
1120 if (ret)
1121 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
1122
1123 if (start)
1124 *start = p->rindex;
1125
1126 p->rindex += sz;
1127 return 0;
1128}
1129
8ba9fd9c 1130void dns_packet_rewind(DnsPacket *p, size_t idx) {
74b2466e
LP		 1131 assert(p);
1132 assert(idx <= p->size);
1133 assert(idx >= DNS_PACKET_HEADER_SIZE);
1134
1135 p->rindex = idx;
1136}
1137
623a4c97
LP		 1138int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
1139 const void *q;
1140 int r;
1141
1142 assert(p);
1143 assert(d);
1144
1145 r = dns_packet_read(p, sz, &q, start);
1146 if (r < 0)
1147 return r;
1148
1149 memcpy(d, q, sz);
1150 return 0;
1151}
1152
f5430a3e
LP		 1153static int dns_packet_read_memdup(
1154 DnsPacket *p, size_t size,
1155 void **ret, size_t *ret_size,
1156 size_t *ret_start) {
1157
1158 const void *src;
1159 size_t start;
1160 int r;
1161
1162 assert(p);
1163 assert(ret);
1164
1165 r = dns_packet_read(p, size, &src, &start);
1166 if (r < 0)
1167 return r;
1168
1169 if (size <= 0)
1170 *ret = NULL;
1171 else {
1172 void *copy;
1173
1174 copy = memdup(src, size);
1175 if (!copy)
1176 return -ENOMEM;
1177
1178 *ret = copy;
1179 }
1180
1181 if (ret_size)
1182 *ret_size = size;
1183 if (ret_start)
1184 *ret_start = start;
1185
1186 return 0;
1187}
1188
74b2466e
LP		 1189int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
1190 const void *d;
1191 int r;
1192
1193 assert(p);
1194
1195 r = dns_packet_read(p, sizeof(uint8_t), &d, start);
1196 if (r < 0)
1197 return r;
1198
1199 *ret = ((uint8_t*) d)[0];
1200 return 0;
1201}
1202
1203int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
1204 const void *d;
1205 int r;
1206
1207 assert(p);
1208
1209 r = dns_packet_read(p, sizeof(uint16_t), &d, start);
1210 if (r < 0)
1211 return r;
1212
725ca0e5
TG		 1213 *ret = unaligned_read_be16(d);
1214
74b2466e
LP		 1215 return 0;
1216}
1217
1218int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
1219 const void *d;
1220 int r;
1221
1222 assert(p);
1223
1224 r = dns_packet_read(p, sizeof(uint32_t), &d, start);
1225 if (r < 0)
1226 return r;
1227
725ca0e5 1228 *ret = unaligned_read_be32(d);
74b2466e
LP		 1229
1230 return 0;
1231}
1232
1233int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
1234 size_t saved_rindex;
1235 const void *d;
1236 char *t;
1237 uint8_t c;
1238 int r;
1239
1240 assert(p);
1241
1242 saved_rindex = p->rindex;
1243
1244 r = dns_packet_read_uint8(p, &c, NULL);
1245 if (r < 0)
1246 goto fail;
1247
1248 r = dns_packet_read(p, c, &d, NULL);
1249 if (r < 0)
1250 goto fail;
1251
1252 if (memchr(d, 0, c)) {
1253 r = -EBADMSG;
1254 goto fail;
1255 }
1256
1257 t = strndup(d, c);
1258 if (!t) {
1259 r = -ENOMEM;
1260 goto fail;
1261 }
1262
1263 if (!utf8_is_valid(t)) {
1264 free(t);
1265 r = -EBADMSG;
1266 goto fail;
1267 }
1268
1269 *ret = t;
1270
1271 if (start)
1272 *start = saved_rindex;
1273
1274 return 0;
1275
1276fail:
1277 dns_packet_rewind(p, saved_rindex);
1278 return r;
1279}
1280
2001c805
LP		 1281int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) {
1282 size_t saved_rindex;
1283 uint8_t c;
1284 int r;
1285
1286 assert(p);
1287
1288 saved_rindex = p->rindex;
1289
1290 r = dns_packet_read_uint8(p, &c, NULL);
1291 if (r < 0)
1292 goto fail;
1293
1294 r = dns_packet_read(p, c, ret, NULL);
1295 if (r < 0)
1296 goto fail;
1297
1298 if (size)
1299 *size = c;
1300 if (start)
1301 *start = saved_rindex;
1302
1303 return 0;
1304
1305fail:
1306 dns_packet_rewind(p, saved_rindex);
1307 return r;
1308}
1309
f6a5fec6
LP		 1310int dns_packet_read_name(
1311 DnsPacket *p,
1312 char **_ret,
1313 bool allow_compression,
1314 size_t *start) {
1315
c75dbf9b 1316 size_t saved_rindex, after_rindex = 0, jump_barrier;
74b2466e
LP		 1317 _cleanup_free_ char *ret = NULL;
1318 size_t n = 0, allocated = 0;
1319 bool first = true;
1320 int r;
1321
1322 assert(p);
1323 assert(_ret);
1324
f6a5fec6
LP		 1325 if (p->refuse_compression)
1326 allow_compression = false;
1327
74b2466e 1328 saved_rindex = p->rindex;
c75dbf9b 1329 jump_barrier = p->rindex;
74b2466e
LP		 1330
1331 for (;;) {
1332 uint8_t c, d;
1333
1334 r = dns_packet_read_uint8(p, &c, NULL);
1335 if (r < 0)
1336 goto fail;
1337
1338 if (c == 0)
1339 /* End of name */
1340 break;
1341 else if (c <= 63) {
74b2466e
LP		 1342 const char *label;
1343
1344 /* Literal label */
1345 r = dns_packet_read(p, c, (const void**) &label, NULL);
1346 if (r < 0)
1347 goto fail;
1348
422baca0 1349 if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) {
74b2466e
LP		 1350 r = -ENOMEM;
1351 goto fail;
1352 }
1353
422baca0 1354 if (first)
74b2466e 1355 first = false;
422baca0
LP		 1356 else
1357 ret[n++] = '.';
1358
1359 r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
1360 if (r < 0)
1361 goto fail;
74b2466e 1362
74b2466e
LP		 1363 n += r;
1364 continue;
151226ab 1365 } else if (allow_compression && (c & 0xc0) == 0xc0) {
74b2466e
LP		 1366 uint16_t ptr;
1367
1368 /* Pointer */
1369 r = dns_packet_read_uint8(p, &d, NULL);
1370 if (r < 0)
1371 goto fail;
1372
1373 ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
c75dbf9b 1374 if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= jump_barrier) {
74b2466e
LP		 1375 r = -EBADMSG;
1376 goto fail;
1377 }
1378
1379 if (after_rindex == 0)
1380 after_rindex = p->rindex;
1381
f131770b 1382 /* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */
c75dbf9b 1383 jump_barrier = ptr;
74b2466e 1384 p->rindex = ptr;
59aa5821
SP		 1385 } else {
1386 r = -EBADMSG;
74b2466e 1387 goto fail;
59aa5821 1388 }
74b2466e
LP		 1389 }
1390
1391 if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
1392 r = -ENOMEM;
1393 goto fail;
1394 }
1395
1396 ret[n] = 0;
1397
1398 if (after_rindex != 0)
1399 p->rindex= after_rindex;
1400
1401 *_ret = ret;
1402 ret = NULL;
1403
1404 if (start)
1405 *start = saved_rindex;
1406
1407 return 0;
1408
1409fail:
1410 dns_packet_rewind(p, saved_rindex);
1411 return r;
1412}
1413
50f1e641
TG		 1414static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *start) {
1415 uint8_t window;
1416 uint8_t length;
1417 const uint8_t *bitmap;
2ad613ad 1418 uint8_t bit = 0;
50f1e641
TG		 1419 unsigned i;
1420 bool found = false;
1421 size_t saved_rindex;
1422 int r;
1423
1424 assert(p);
1425 assert(types);
1426
1427 saved_rindex = p->rindex;
1428
1429 r = bitmap_ensure_allocated(types);
1430 if (r < 0)
1431 goto fail;
1432
1433 r = dns_packet_read_uint8(p, &window, NULL);
1434 if (r < 0)
1435 goto fail;
1436
1437 r = dns_packet_read_uint8(p, &length, NULL);
1438 if (r < 0)
1439 goto fail;
1440
1441 if (length == 0 || length > 32)
1442 return -EBADMSG;
1443
1444 r = dns_packet_read(p, length, (const void **)&bitmap, NULL);
1445 if (r < 0)
1446 goto fail;
1447
1448 for (i = 0; i < length; i++) {
1449 uint8_t bitmask = 1 << 7;
50f1e641
TG		 1450
1451 if (!bitmap[i]) {
1452 found = false;
2ad613ad 1453 bit += 8;
50f1e641
TG		 1454 continue;
1455 }
1456
1457 found = true;
1458
1459 while (bitmask) {
1460 if (bitmap[i] & bitmask) {
1461 uint16_t n;
1462
50f1e641
TG		 1463 n = (uint16_t) window << 8 | (uint16_t) bit;
1464
8e6edc49
TG		 1465 /* Ignore pseudo-types. see RFC4034 section 4.1.2 */
1466 if (dns_type_is_pseudo(n))
1467 continue;
1468
50f1e641
TG		 1469 r = bitmap_set(*types, n);
1470 if (r < 0)
1471 goto fail;
1472 }
1473
1474 bit ++;
1475 bitmask >>= 1;
1476 }
1477 }
1478
1479 if (!found)
1480 return -EBADMSG;
1481
1482 if (start)
1483 *start = saved_rindex;
1484
1485 return 0;
1486fail:
1487 dns_packet_rewind(p, saved_rindex);
1488 return r;
1489}
1490
89492aaf
TG		 1491static int dns_packet_read_type_windows(DnsPacket *p, Bitmap **types, size_t size, size_t *start) {
1492 size_t saved_rindex;
1493 int r;
1494
1495 saved_rindex = p->rindex;
1496
1497 while (p->rindex < saved_rindex + size) {
1498 r = dns_packet_read_type_window(p, types, NULL);
1499 if (r < 0)
1500 goto fail;
1501
1502 /* don't read past end of current RR */
1503 if (p->rindex > saved_rindex + size) {
1504 r = -EBADMSG;
1505 goto fail;
1506 }
1507 }
1508
1509 if (p->rindex != saved_rindex + size) {
1510 r = -EBADMSG;
1511 goto fail;
1512 }
1513
1514 if (start)
1515 *start = saved_rindex;
1516
1517 return 0;
1518fail:
1519 dns_packet_rewind(p, saved_rindex);
1520 return r;
1521}
1522
d2579eec 1523int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start) {
faa133f3 1524 _cleanup_free_ char *name = NULL;
d2579eec 1525 bool cache_flush = false;
faa133f3
LP		 1526 uint16_t class, type;
1527 DnsResourceKey *key;
74b2466e
LP		 1528 size_t saved_rindex;
1529 int r;
1530
1531 assert(p);
1532 assert(ret);
1533
1534 saved_rindex = p->rindex;
1535
151226ab 1536 r = dns_packet_read_name(p, &name, true, NULL);
74b2466e
LP		 1537 if (r < 0)
1538 goto fail;
1539
faa133f3 1540 r = dns_packet_read_uint16(p, &type, NULL);
74b2466e
LP		 1541 if (r < 0)
1542 goto fail;
1543
faa133f3 1544 r = dns_packet_read_uint16(p, &class, NULL);
74b2466e
LP		 1545 if (r < 0)
1546 goto fail;
1547
23502de3
DM		 1548 if (p->protocol == DNS_PROTOCOL_MDNS) {
1549 /* See RFC6762, Section 10.2 */
1550
d2579eec 1551 if (type != DNS_TYPE_OPT && (class & MDNS_RR_CACHE_FLUSH)) {
23502de3 1552 class &= ~MDNS_RR_CACHE_FLUSH;
d2579eec
LP		 1553 cache_flush = true;
1554 }
23502de3
DM		 1555 }
1556
faa133f3
LP		 1557 key = dns_resource_key_new_consume(class, type, name);
1558 if (!key) {
1559 r = -ENOMEM;
1560 goto fail;
1561 }
1562
1563 name = NULL;
1564 *ret = key;
74b2466e 1565
d2579eec
LP		 1566 if (ret_cache_flush)
1567 *ret_cache_flush = cache_flush;
74b2466e
LP		 1568 if (start)
1569 *start = saved_rindex;
1570
1571 return 0;
1572fail:
1573 dns_packet_rewind(p, saved_rindex);
1574 return r;
1575}
1576
afbc4f26
ZJS		 1577static bool loc_size_ok(uint8_t size) {
1578 uint8_t m = size >> 4, e = size & 0xF;
1579
1580 return m <= 9 && e <= 9 && (m > 0 || e == 0);
1581}
1582
d2579eec 1583int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, size_t *start) {
faa133f3
LP		 1584 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1585 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
74b2466e
LP		 1586 size_t saved_rindex, offset;
1587 uint16_t rdlength;
d2579eec 1588 bool cache_flush;
74b2466e
LP		 1589 int r;
1590
1591 assert(p);
1592 assert(ret);
1593
4e0296a9 1594 saved_rindex = p->rindex;
74b2466e 1595
d2579eec 1596 r = dns_packet_read_key(p, &key, &cache_flush, NULL);
74b2466e
LP		 1597 if (r < 0)
1598 goto fail;
1599
222148b6 1600 if (!dns_class_is_valid_rr(key->class)||
c463eb78 1601 !dns_type_is_valid_rr(key->type)) {
0e2bcd6a
LP		 1602 r = -EBADMSG;
1603 goto fail;
1604 }
1605
faa133f3
LP		 1606 rr = dns_resource_record_new(key);
1607 if (!rr) {
1608 r = -ENOMEM;
1609 goto fail;
1610 }
1611
74b2466e
LP		 1612 r = dns_packet_read_uint32(p, &rr->ttl, NULL);
1613 if (r < 0)
1614 goto fail;
1615
0d0b52d7
LP		 1616 /* RFC 2181, Section 8, suggests to
1617 * treat a TTL with the MSB set as a zero TTL. */
1618 if (rr->ttl & UINT32_C(0x80000000))
1619 rr->ttl = 0;
1620
74b2466e
LP		 1621 r = dns_packet_read_uint16(p, &rdlength, NULL);
1622 if (r < 0)
1623 goto fail;
1624
1625 if (p->rindex + rdlength > p->size) {
1626 r = -EBADMSG;
1627 goto fail;
1628 }
1629
1630 offset = p->rindex;
1631
faa133f3 1632 switch (rr->key->type) {
74b2466e 1633
9c92ce6d
LP		 1634 case DNS_TYPE_SRV:
1635 r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
1636 if (r < 0)
1637 goto fail;
1638 r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
1639 if (r < 0)
1640 goto fail;
1641 r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
1642 if (r < 0)
1643 goto fail;
151226ab 1644 r = dns_packet_read_name(p, &rr->srv.name, true, NULL);
9c92ce6d
LP		 1645 break;
1646
74b2466e
LP		 1647 case DNS_TYPE_PTR:
1648 case DNS_TYPE_NS:
1649 case DNS_TYPE_CNAME:
8ac4e9e1 1650 case DNS_TYPE_DNAME:
151226ab 1651 r = dns_packet_read_name(p, &rr->ptr.name, true, NULL);
74b2466e
LP		 1652 break;
1653
1654 case DNS_TYPE_HINFO:
1655 r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
1656 if (r < 0)
1657 goto fail;
1658
1659 r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
1660 break;
1661
9de3e329 1662 case DNS_TYPE_SPF: /* exactly the same as TXT */
1ccda9b7
LP		 1663 case DNS_TYPE_TXT:
1664 if (rdlength <= 0) {
2001c805 1665 DnsTxtItem *i;
1ccda9b7
LP		 1666 /* RFC 6763, section 6.1 suggests to treat
1667 * empty TXT RRs as equivalent to a TXT record
1668 * with a single empty string. */
0e3434ae 1669
2001c805
LP		 1670 i = malloc0(offsetof(DnsTxtItem, data) + 1); /* for safety reasons we add an extra NUL byte */
1671 if (!i)
1672 return -ENOMEM;
1673
1674 rr->txt.items = i;
1ccda9b7 1675 } else {
2001c805
LP		 1676 DnsTxtItem *last = NULL;
1677
1ccda9b7 1678 while (p->rindex < offset + rdlength) {
2001c805
LP		 1679 DnsTxtItem *i;
1680 const void *data;
1681 size_t sz;
2e276efc 1682
2001c805 1683 r = dns_packet_read_raw_string(p, &data, &sz, NULL);
1ccda9b7 1684 if (r < 0)
2001c805 1685 return r;
1ccda9b7 1686
2001c805
LP		 1687 i = malloc0(offsetof(DnsTxtItem, data) + sz + 1); /* extra NUL byte at the end */
1688 if (!i)
1689 return -ENOMEM;
1690
1691 memcpy(i->data, data, sz);
1692 i->length = sz;
1693
1694 LIST_INSERT_AFTER(items, rr->txt.items, last, i);
1695 last = i;
1ccda9b7 1696 }
6a6fc3df
LP		 1697 }
1698
1699 r = 0;
2e276efc 1700 break;
2e276efc 1701
74b2466e 1702 case DNS_TYPE_A:
623a4c97 1703 r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
74b2466e
LP		 1704 break;
1705
1706 case DNS_TYPE_AAAA:
623a4c97 1707 r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
74b2466e
LP		 1708 break;
1709
7e8e0422 1710 case DNS_TYPE_SOA:
151226ab 1711 r = dns_packet_read_name(p, &rr->soa.mname, true, NULL);
7e8e0422
LP		 1712 if (r < 0)
1713 goto fail;
1714
151226ab 1715 r = dns_packet_read_name(p, &rr->soa.rname, true, NULL);
7e8e0422
LP		 1716 if (r < 0)
1717 goto fail;
1718
1719 r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
1720 if (r < 0)
1721 goto fail;
1722
1723 r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
1724 if (r < 0)
1725 goto fail;
1726
1727 r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
1728 if (r < 0)
1729 goto fail;
1730
1731 r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
1732 if (r < 0)
1733 goto fail;
1734
1735 r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
1736 break;
1737
623a4c97 1738 case DNS_TYPE_MX:
946c7094
ZJS		 1739 r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
1740 if (r < 0)
1741 goto fail;
1742
151226ab 1743 r = dns_packet_read_name(p, &rr->mx.exchange, true, NULL);
946c7094
ZJS		 1744 break;
1745
0dae31d4
ZJS		 1746 case DNS_TYPE_LOC: {
1747 uint8_t t;
1748 size_t pos;
1749
1750 r = dns_packet_read_uint8(p, &t, &pos);
1751 if (r < 0)
1752 goto fail;
1753
1754 if (t == 0) {
1755 rr->loc.version = t;
1756
1757 r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
1758 if (r < 0)
1759 goto fail;
1760
afbc4f26
ZJS		 1761 if (!loc_size_ok(rr->loc.size)) {
1762 r = -EBADMSG;
1763 goto fail;
1764 }
1765
0dae31d4
ZJS		 1766 r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
1767 if (r < 0)
1768 goto fail;
1769
afbc4f26
ZJS		 1770 if (!loc_size_ok(rr->loc.horiz_pre)) {
1771 r = -EBADMSG;
1772 goto fail;
1773 }
1774
0dae31d4
ZJS		 1775 r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
1776 if (r < 0)
1777 goto fail;
1778
afbc4f26
ZJS		 1779 if (!loc_size_ok(rr->loc.vert_pre)) {
1780 r = -EBADMSG;
1781 goto fail;
1782 }
1783
0dae31d4
ZJS		 1784 r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
1785 if (r < 0)
1786 goto fail;
1787
1788 r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
1789 if (r < 0)
1790 goto fail;
1791
1792 r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
1793 if (r < 0)
1794 goto fail;
1795
1796 break;
1797 } else {
1798 dns_packet_rewind(p, pos);
1799 rr->unparseable = true;
afbc4f26 1800 goto unparseable;
0dae31d4
ZJS		 1801 }
1802 }
1803
abf126a3
TG		 1804 case DNS_TYPE_DS:
1805 r = dns_packet_read_uint16(p, &rr->ds.key_tag, NULL);
1806 if (r < 0)
1807 goto fail;
1808
1809 r = dns_packet_read_uint8(p, &rr->ds.algorithm, NULL);
1810 if (r < 0)
1811 goto fail;
1812
1813 r = dns_packet_read_uint8(p, &rr->ds.digest_type, NULL);
1814 if (r < 0)
1815 goto fail;
1816
f5430a3e
LP		 1817 r = dns_packet_read_memdup(p, rdlength - 4,
1818 &rr->ds.digest, &rr->ds.digest_size,
1819 NULL);
abf126a3
TG		 1820 if (r < 0)
1821 goto fail;
1822
f1d178cc
TG		 1823 if (rr->ds.digest_size <= 0) {
1824 /* the accepted size depends on the algorithm, but for now
1825 just ensure that the value is greater than zero */
1826 r = -EBADMSG;
1827 goto fail;
1828 }
1829
abf126a3 1830 break;
d75acfb0 1831
623a4c97 1832 case DNS_TYPE_SSHFP:
42cc2eeb
LP		 1833 r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
1834 if (r < 0)
1835 goto fail;
1836
1837 r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL);
1838 if (r < 0)
1839 goto fail;
1840
f5430a3e 1841 r = dns_packet_read_memdup(p, rdlength - 2,
549c1a25 1842 &rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size,
f5430a3e 1843 NULL);
f1d178cc 1844
549c1a25 1845 if (rr->sshfp.fingerprint_size <= 0) {
f1d178cc
TG		 1846 /* the accepted size depends on the algorithm, but for now
1847 just ensure that the value is greater than zero */
1848 r = -EBADMSG;
1849 goto fail;
1850 }
1851
8db0d2f5
ZJS		 1852 break;
1853
f91dc240
LP		 1854 case DNS_TYPE_DNSKEY:
1855 r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL);
8db0d2f5
ZJS		 1856 if (r < 0)
1857 goto fail;
1858
f91dc240 1859 r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL);
8db0d2f5
ZJS		 1860 if (r < 0)
1861 goto fail;
1862
8db0d2f5
ZJS		 1863 r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
1864 if (r < 0)
1865 goto fail;
1866
f5430a3e
LP		 1867 r = dns_packet_read_memdup(p, rdlength - 4,
1868 &rr->dnskey.key, &rr->dnskey.key_size,
1869 NULL);
f1d178cc
TG		 1870
1871 if (rr->dnskey.key_size <= 0) {
1872 /* the accepted size depends on the algorithm, but for now
1873 just ensure that the value is greater than zero */
1874 r = -EBADMSG;
1875 goto fail;
1876 }
1877
42cc2eeb
LP		 1878 break;
1879
151226ab
ZJS		 1880 case DNS_TYPE_RRSIG:
1881 r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL);
1882 if (r < 0)
1883 goto fail;
1884
1885 r = dns_packet_read_uint8(p, &rr->rrsig.algorithm, NULL);
1886 if (r < 0)
1887 goto fail;
1888
1889 r = dns_packet_read_uint8(p, &rr->rrsig.labels, NULL);
1890 if (r < 0)
1891 goto fail;
1892
1893 r = dns_packet_read_uint32(p, &rr->rrsig.original_ttl, NULL);
1894 if (r < 0)
1895 goto fail;
1896
1897 r = dns_packet_read_uint32(p, &rr->rrsig.expiration, NULL);
1898 if (r < 0)
1899 goto fail;
1900
1901 r = dns_packet_read_uint32(p, &rr->rrsig.inception, NULL);
1902 if (r < 0)
1903 goto fail;
1904
1905 r = dns_packet_read_uint16(p, &rr->rrsig.key_tag, NULL);
1906 if (r < 0)
1907 goto fail;
1908
1909 r = dns_packet_read_name(p, &rr->rrsig.signer, false, NULL);
1910 if (r < 0)
1911 goto fail;
1912
f5430a3e
LP		 1913 r = dns_packet_read_memdup(p, offset + rdlength - p->rindex,
1914 &rr->rrsig.signature, &rr->rrsig.signature_size,
1915 NULL);
f1d178cc
TG		 1916
1917 if (rr->rrsig.signature_size <= 0) {
1918 /* the accepted size depends on the algorithm, but for now
1919 just ensure that the value is greater than zero */
1920 r = -EBADMSG;
1921 goto fail;
1922 }
1923
151226ab
ZJS		 1924 break;
1925
d84e543d
DM		 1926 case DNS_TYPE_NSEC: {
1927
1928 /*
e5abebab 1929 * RFC6762, section 18.14 explictly states mDNS should use name compression.
d84e543d
DM		 1930 * This contradicts RFC3845, section 2.1.1
1931 */
1932
1933 bool allow_compressed = p->protocol == DNS_PROTOCOL_MDNS;
1934
1935 r = dns_packet_read_name(p, &rr->nsec.next_domain_name, allow_compressed, NULL);
50f1e641
TG		 1936 if (r < 0)
1937 goto fail;
1938
89492aaf
TG		 1939 r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL);
1940 if (r < 0)
1941 goto fail;
1942
09eaf68c
TG		 1943 /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
1944 * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records
1945 * without the NSEC bit set. */
50f1e641
TG		 1946
1947 break;
d84e543d 1948 }
5d45a880
TG		 1949 case DNS_TYPE_NSEC3: {
1950 uint8_t size;
1951
1952 r = dns_packet_read_uint8(p, &rr->nsec3.algorithm, NULL);
1953 if (r < 0)
1954 goto fail;
1955
1956 r = dns_packet_read_uint8(p, &rr->nsec3.flags, NULL);
1957 if (r < 0)
1958 goto fail;
1959
1960 r = dns_packet_read_uint16(p, &rr->nsec3.iterations, NULL);
1961 if (r < 0)
1962 goto fail;
1963
f1d178cc 1964 /* this may be zero */
5d45a880
TG		 1965 r = dns_packet_read_uint8(p, &size, NULL);
1966 if (r < 0)
1967 goto fail;
1968
f5430a3e 1969 r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
5d45a880
TG		 1970 if (r < 0)
1971 goto fail;
1972
5d45a880
TG		 1973 r = dns_packet_read_uint8(p, &size, NULL);
1974 if (r < 0)
1975 goto fail;
1976
f1d178cc
TG		 1977 if (size <= 0) {
1978 r = -EBADMSG;
1979 goto fail;
1980 }
1981
f5430a3e 1982 r = dns_packet_read_memdup(p, size, &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size, NULL);
5d45a880
TG		 1983 if (r < 0)
1984 goto fail;
1985
6b9308d1 1986 r = dns_packet_read_type_windows(p, &rr->nsec3.types, offset + rdlength - p->rindex, NULL);
5d45a880
TG		 1987 if (r < 0)
1988 goto fail;
1989
0bbd72b2
TG		 1990 /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
1991
5d45a880
TG		 1992 break;
1993 }
d75acfb0 1994
48d45d2b
ZJS		 1995 case DNS_TYPE_TLSA:
1996 r = dns_packet_read_uint8(p, &rr->tlsa.cert_usage, NULL);
1997 if (r < 0)
1998 goto fail;
1999
2000 r = dns_packet_read_uint8(p, &rr->tlsa.selector, NULL);
2001 if (r < 0)
2002 goto fail;
2003
2004 r = dns_packet_read_uint8(p, &rr->tlsa.matching_type, NULL);
2005 if (r < 0)
2006 goto fail;
2007
2008 r = dns_packet_read_memdup(p, rdlength - 3,
2009 &rr->tlsa.data, &rr->tlsa.data_size,
2010 NULL);
2011 if (rr->tlsa.data_size <= 0) {
2012 /* the accepted size depends on the algorithm, but for now
2013 just ensure that the value is greater than zero */
2014 r = -EBADMSG;
2015 goto fail;
2016 }
2017
2018 break;
2019
d75acfb0 2020 case DNS_TYPE_OPT: /* we only care about the header of OPT for now. */
74b2466e 2021 default:
afbc4f26 2022 unparseable:
f5430a3e 2023 r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.size, NULL);
74b2466e
LP		 2024 if (r < 0)
2025 goto fail;
74b2466e
LP		 2026 break;
2027 }
2028 if (r < 0)
2029 goto fail;
2030 if (p->rindex != offset + rdlength) {
2031 r = -EBADMSG;
2032 goto fail;
2033 }
2034
2035 *ret = rr;
2036 rr = NULL;
2037
d2579eec
LP		 2038 if (ret_cache_flush)
2039 *ret_cache_flush = cache_flush;
74b2466e
LP		 2040 if (start)
2041 *start = saved_rindex;
2042
2043 return 0;
2044fail:
2045 dns_packet_rewind(p, saved_rindex);
2046 return r;
2047}
2048
c3f7000e
LP		 2049static bool opt_is_good(DnsResourceRecord *rr, bool *rfc6975) {
2050 const uint8_t* p;
2051 bool found_dau_dhu_n3u = false;
2052 size_t l;
2053
2054 /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in
2055 * a reply). */
2056
2057 assert(rr);
2058 assert(rr->key->type == DNS_TYPE_OPT);
2059
2060 /* Check that the version is 0 */
2061 if (((rr->ttl >> 16) & UINT32_C(0xFF)) != 0)
2062 return false;
2063
2064 p = rr->opt.data;
2065 l = rr->opt.size;
2066 while (l > 0) {
2067 uint16_t option_code, option_length;
2068
2069 /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */
2070 if (l < 4U)
2071 return false;
2072
2073 option_code = unaligned_read_be16(p);
2074 option_length = unaligned_read_be16(p + 2);
2075
2076 if (l < option_length + 4U)
2077 return false;
2078
2079 /* RFC 6975 DAU, DHU or N3U fields found. */
2080 if (IN_SET(option_code, 5, 6, 7))
2081 found_dau_dhu_n3u = true;
2082
2083 p += option_length + 4U;
2084 l -= option_length + 4U;
2085 }
2086
2087 *rfc6975 = found_dau_dhu_n3u;
2088 return true;
2089}
2090
faa133f3
LP		 2091int dns_packet_extract(DnsPacket *p) {
2092 _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
2093 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
2094 size_t saved_rindex;
2095 unsigned n, i;
74b2466e
LP		 2096 int r;
2097
a4076574
LP		 2098 if (p->extracted)
2099 return 0;
2100
faa133f3 2101 saved_rindex = p->rindex;
322345fd
LP		 2102 dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
2103
3cb10d3a 2104 n = DNS_PACKET_QDCOUNT(p);
faa133f3
LP		 2105 if (n > 0) {
2106 question = dns_question_new(n);
2107 if (!question) {
2108 r = -ENOMEM;
2109 goto finish;
2110 }
74b2466e 2111
faa133f3
LP		 2112 for (i = 0; i < n; i++) {
2113 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
d2579eec 2114 bool cache_flush;
74b2466e 2115
d2579eec 2116 r = dns_packet_read_key(p, &key, &cache_flush, NULL);
faa133f3
LP		 2117 if (r < 0)
2118 goto finish;
74b2466e 2119
d2579eec
LP		 2120 if (cache_flush) {
2121 r = -EBADMSG;
2122 goto finish;
2123 }
2124
c463eb78
LP		 2125 if (!dns_type_is_valid_query(key->type)) {
2126 r = -EBADMSG;
2127 goto finish;
2128 }
2129
faa133f3
LP		 2130 r = dns_question_add(question, key);
2131 if (r < 0)
2132 goto finish;
2133 }
2134 }
322345fd 2135
faa133f3
LP		 2136 n = DNS_PACKET_RRCOUNT(p);
2137 if (n > 0) {
ebc8a106 2138 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL;
c3f7000e
LP		 2139 bool bad_opt = false;
2140
faa133f3
LP		 2141 answer = dns_answer_new(n);
2142 if (!answer) {
2143 r = -ENOMEM;
2144 goto finish;
2145 }
322345fd 2146
faa133f3
LP		 2147 for (i = 0; i < n; i++) {
2148 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
ff7febd5 2149 bool cache_flush;
322345fd 2150
ff7febd5 2151 r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
faa133f3
LP		 2152 if (r < 0)
2153 goto finish;
322345fd 2154
f57e3cd5
LP		 2155 /* Try to reduce memory usage a bit */
2156 if (previous)
2157 dns_resource_key_reduce(&rr->key, &previous->key);
2158
d75acfb0 2159 if (rr->key->type == DNS_TYPE_OPT) {
c3f7000e
LP		 2160 bool has_rfc6975;
2161
2162 if (p->opt || bad_opt) {
2163 /* Multiple OPT RRs? if so, let's ignore all, because there's something wrong
2164 * with the server, and if one is valid we wouldn't know which one. */
2165 log_debug("Multiple OPT RRs detected, ignoring all.");
2166 bad_opt = true;
2167 continue;
2168 }
e6b57b37 2169
ff7febd5 2170 if (!dns_name_is_root(DNS_RESOURCE_KEY_NAME(rr->key))) {
c3f7000e
LP		 2171 /* If the OPT RR qis not owned by the root domain, then it is bad, let's ignore
2172 * it. */
2173 log_debug("OPT RR is not owned by root domain, ignoring.");
2174 bad_opt = true;
2175 continue;
2176 }
2177
2178 if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
2179 /* OPT RR is in the wrong section? Some Belkin routers do this. This is a hint
2180 * the EDNS implementation is borked, like the Belkin one is, hence ignore
2181 * it. */
2182 log_debug("OPT RR in wrong section, ignoring.");
2183 bad_opt = true;
2184 continue;
ff7febd5
LP		 2185 }
2186
c3f7000e
LP		 2187 if (!opt_is_good(rr, &has_rfc6975)) {
2188 log_debug("Malformed OPT RR, ignoring.");
2189 bad_opt = true;
2190 continue;
2191 }
e6b57b37 2192
c3f7000e 2193 if (has_rfc6975) {
ebc8a106
LP		 2194 /* If the OPT RR contains RFC6975 algorithm data, then this is indication that
2195 * the server just copied the OPT it got from us (which contained that data)
2196 * back into the reply. If so, then it doesn't properly support EDNS, as
2197 * RFC6975 makes it very clear that the algorithm data should only be contained
2198 * in questions, never in replies. Crappy Belkin routers copy the OPT data for
2199 * example, hence let's detect this so that we downgrade early. */
c3f7000e
LP		 2200 log_debug("OPT RR contained RFC6975 data, ignoring.");
2201 bad_opt = true;
2202 continue;
e6b57b37 2203 }
d75acfb0
LP		 2204
2205 p->opt = dns_resource_record_ref(rr);
2206 } else {
105e1512 2207
c3f7000e
LP		 2208 /* According to RFC 4795, section 2.9. only the RRs from the Answer section shall be
2209 * cached. Hence mark only those RRs as cacheable by default, but not the ones from the
2210 * Additional or Authority sections. */
105e1512
LP		 2211
2212 r = dns_answer_add(answer, rr, p->ifindex,
d2579eec
LP		 2213 (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) |
2214 (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0));
d75acfb0
LP		 2215 if (r < 0)
2216 goto finish;
2217 }
ebc8a106
LP		 2218
2219 /* Remember this RR, so that we potentically can merge it's ->key object with the next RR. Note
2220 * that we only do this if we actually decided to keep the RR around. */
2221 dns_resource_record_unref(previous);
2222 previous = dns_resource_record_ref(rr);
faa133f3 2223 }
c3f7000e
LP		 2224
2225 if (bad_opt)
2226 p->opt = dns_resource_record_unref(p->opt);
322345fd
LP		 2227 }
2228
faa133f3
LP		 2229 p->question = question;
2230 question = NULL;
322345fd 2231
faa133f3
LP		 2232 p->answer = answer;
2233 answer = NULL;
322345fd 2234
a4076574
LP		 2235 p->extracted = true;
2236
faa133f3 2237 r = 0;
322345fd
LP		 2238
2239finish:
2240 p->rindex = saved_rindex;
2241 return r;
2242}
2243
8af5b883
LP		 2244int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) {
2245 int r;
2246
2247 assert(p);
2248 assert(key);
2249
2250 /* Checks if the specified packet is a reply for the specified
2251 * key and the specified key is the only one in the question
2252 * section. */
2253
2254 if (DNS_PACKET_QR(p) != 1)
2255 return 0;
2256
2257 /* Let's unpack the packet, if that hasn't happened yet. */
2258 r = dns_packet_extract(p);
2259 if (r < 0)
2260 return r;
2261
2262 if (p->question->n_keys != 1)
2263 return 0;
2264
2265 return dns_resource_key_equal(p->question->keys[0], key);
2266}
2267
74b2466e
LP		 2268static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
2269 [DNS_RCODE_SUCCESS] = "SUCCESS",
2270 [DNS_RCODE_FORMERR] = "FORMERR",
2271 [DNS_RCODE_SERVFAIL] = "SERVFAIL",
2272 [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
2273 [DNS_RCODE_NOTIMP] = "NOTIMP",
2274 [DNS_RCODE_REFUSED] = "REFUSED",
2275 [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
2276 [DNS_RCODE_YXRRSET] = "YRRSET",
2277 [DNS_RCODE_NXRRSET] = "NXRRSET",
2278 [DNS_RCODE_NOTAUTH] = "NOTAUTH",
2279 [DNS_RCODE_NOTZONE] = "NOTZONE",
2280 [DNS_RCODE_BADVERS] = "BADVERS",
2281 [DNS_RCODE_BADKEY] = "BADKEY",
2282 [DNS_RCODE_BADTIME] = "BADTIME",
2283 [DNS_RCODE_BADMODE] = "BADMODE",
2284 [DNS_RCODE_BADNAME] = "BADNAME",
2285 [DNS_RCODE_BADALG] = "BADALG",
2286 [DNS_RCODE_BADTRUNC] = "BADTRUNC",
2287};
2288DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
1716f6dc
LP		 2289
2290static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
2291 [DNS_PROTOCOL_DNS] = "dns",
2292 [DNS_PROTOCOL_MDNS] = "mdns",
2293 [DNS_PROTOCOL_LLMNR] = "llmnr",
2294};
2295DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);
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