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resolved: add support for explicitly forgetting everything we learnt about DNS server...
[thirdparty/systemd.git] / src / resolve / resolved-dns-packet.c
1 /***
2 This file is part of systemd.
3
4 Copyright 2014 Lennart Poettering
5
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
10
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
15
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
18 ***/
19
20 #include "alloc-util.h"
21 #include "dns-domain.h"
22 #include "resolved-dns-packet.h"
23 #include "string-table.h"
24 #include "strv.h"
25 #include "unaligned.h"
26 #include "utf8.h"
27 #include "util.h"
28
29 #define EDNS0_OPT_DO (1<<15)
30
31 assert_cc(DNS_PACKET_SIZE_START > DNS_PACKET_HEADER_SIZE)
32
33 typedef struct DnsPacketRewinder {
34 DnsPacket *packet;
35 size_t saved_rindex;
36 } DnsPacketRewinder;
37
38 static void rewind_dns_packet(DnsPacketRewinder *rewinder) {
39 if (rewinder->packet)
40 dns_packet_rewind(rewinder->packet, rewinder->saved_rindex);
41 }
42
43 #define INIT_REWINDER(rewinder, p) do { rewinder.packet = p; rewinder.saved_rindex = p->rindex; } while (0)
44 #define CANCEL_REWINDER(rewinder) do { rewinder.packet = NULL; } while (0)
45
46 int dns_packet_new(
47 DnsPacket **ret,
48 DnsProtocol protocol,
49 size_t min_alloc_dsize,
50 size_t max_size) {
51
52 DnsPacket *p;
53 size_t a;
54
55 assert(ret);
56 assert(max_size >= DNS_PACKET_HEADER_SIZE);
57
58 if (max_size > DNS_PACKET_SIZE_MAX)
59 max_size = DNS_PACKET_SIZE_MAX;
60
61 /* The caller may not check what is going to be truly allocated, so do not allow to
62 * allocate a DNS packet bigger than DNS_PACKET_SIZE_MAX.
63 */
64 if (min_alloc_dsize > DNS_PACKET_SIZE_MAX) {
65 log_error("Requested packet data size too big: %zu", min_alloc_dsize);
66 return -EFBIG;
67 }
68
69 /* When dns_packet_new() is called with min_alloc_dsize == 0, allocate more than the
70 * absolute minimum (which is the dns packet header size), to avoid
71 * resizing immediately again after appending the first data to the packet.
72 */
73 if (min_alloc_dsize < DNS_PACKET_HEADER_SIZE)
74 a = DNS_PACKET_SIZE_START;
75 else
76 a = min_alloc_dsize;
77
78 /* round up to next page size */
79 a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));
80
81 /* make sure we never allocate more than useful */
82 if (a > max_size)
83 a = max_size;
84
85 p = malloc0(ALIGN(sizeof(DnsPacket)) + a);
86 if (!p)
87 return -ENOMEM;
88
89 p->size = p->rindex = DNS_PACKET_HEADER_SIZE;
90 p->allocated = a;
91 p->max_size = max_size;
92 p->protocol = protocol;
93 p->opt_start = p->opt_size = (size_t) -1;
94 p->n_ref = 1;
95
96 *ret = p;
97
98 return 0;
99 }
100
101 void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated) {
102
103 DnsPacketHeader *h;
104
105 assert(p);
106
107 h = DNS_PACKET_HEADER(p);
108
109 switch(p->protocol) {
110 case DNS_PROTOCOL_LLMNR:
111 assert(!truncated);
112
113 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
114 0 /* opcode */,
115 0 /* c */,
116 0 /* tc */,
117 0 /* t */,
118 0 /* ra */,
119 0 /* ad */,
120 0 /* cd */,
121 0 /* rcode */));
122 break;
123
124 case DNS_PROTOCOL_MDNS:
125 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
126 0 /* opcode */,
127 0 /* aa */,
128 truncated /* tc */,
129 0 /* rd (ask for recursion) */,
130 0 /* ra */,
131 0 /* ad */,
132 0 /* cd */,
133 0 /* rcode */));
134 break;
135
136 default:
137 assert(!truncated);
138
139 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
140 0 /* opcode */,
141 0 /* aa */,
142 0 /* tc */,
143 1 /* rd (ask for recursion) */,
144 0 /* ra */,
145 0 /* ad */,
146 dnssec_checking_disabled /* cd */,
147 0 /* rcode */));
148 }
149 }
150
151 int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled) {
152 DnsPacket *p;
153 int r;
154
155 assert(ret);
156
157 r = dns_packet_new(&p, protocol, min_alloc_dsize, DNS_PACKET_SIZE_MAX);
158 if (r < 0)
159 return r;
160
161 /* Always set the TC bit to 0 initially.
162 * If there are multiple packets later, we'll update the bit shortly before sending.
163 */
164 dns_packet_set_flags(p, dnssec_checking_disabled, false);
165
166 *ret = p;
167 return 0;
168 }
169
170 DnsPacket *dns_packet_ref(DnsPacket *p) {
171
172 if (!p)
173 return NULL;
174
175 assert(!p->on_stack);
176
177 assert(p->n_ref > 0);
178 p->n_ref++;
179 return p;
180 }
181
182 static void dns_packet_free(DnsPacket *p) {
183 char *s;
184
185 assert(p);
186
187 dns_question_unref(p->question);
188 dns_answer_unref(p->answer);
189 dns_resource_record_unref(p->opt);
190
191 while ((s = hashmap_steal_first_key(p->names)))
192 free(s);
193 hashmap_free(p->names);
194
195 free(p->_data);
196
197 if (!p->on_stack)
198 free(p);
199 }
200
201 DnsPacket *dns_packet_unref(DnsPacket *p) {
202 if (!p)
203 return NULL;
204
205 assert(p->n_ref > 0);
206
207 dns_packet_unref(p->more);
208
209 if (p->n_ref == 1)
210 dns_packet_free(p);
211 else
212 p->n_ref--;
213
214 return NULL;
215 }
216
217 int dns_packet_validate(DnsPacket *p) {
218 assert(p);
219
220 if (p->size < DNS_PACKET_HEADER_SIZE)
221 return -EBADMSG;
222
223 if (p->size > DNS_PACKET_SIZE_MAX)
224 return -EBADMSG;
225
226 return 1;
227 }
228
229 int dns_packet_validate_reply(DnsPacket *p) {
230 int r;
231
232 assert(p);
233
234 r = dns_packet_validate(p);
235 if (r < 0)
236 return r;
237
238 if (DNS_PACKET_QR(p) != 1)
239 return 0;
240
241 if (DNS_PACKET_OPCODE(p) != 0)
242 return -EBADMSG;
243
244 switch (p->protocol) {
245
246 case DNS_PROTOCOL_LLMNR:
247 /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
248 if (DNS_PACKET_QDCOUNT(p) != 1)
249 return -EBADMSG;
250
251 break;
252
253 case DNS_PROTOCOL_MDNS:
254 /* RFC 6762, Section 18 */
255 if (DNS_PACKET_RCODE(p) != 0)
256 return -EBADMSG;
257
258 break;
259
260 default:
261 break;
262 }
263
264 return 1;
265 }
266
267 int dns_packet_validate_query(DnsPacket *p) {
268 int r;
269
270 assert(p);
271
272 r = dns_packet_validate(p);
273 if (r < 0)
274 return r;
275
276 if (DNS_PACKET_QR(p) != 0)
277 return 0;
278
279 if (DNS_PACKET_OPCODE(p) != 0)
280 return -EBADMSG;
281
282 if (DNS_PACKET_TC(p))
283 return -EBADMSG;
284
285 switch (p->protocol) {
286
287 case DNS_PROTOCOL_LLMNR:
288 case DNS_PROTOCOL_DNS:
289 /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
290 if (DNS_PACKET_QDCOUNT(p) != 1)
291 return -EBADMSG;
292
293 /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
294 if (DNS_PACKET_ANCOUNT(p) > 0)
295 return -EBADMSG;
296
297 /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
298 if (DNS_PACKET_NSCOUNT(p) > 0)
299 return -EBADMSG;
300
301 break;
302
303 case DNS_PROTOCOL_MDNS:
304 /* RFC 6762, Section 18 */
305 if (DNS_PACKET_AA(p) != 0 ||
306 DNS_PACKET_RD(p) != 0 ||
307 DNS_PACKET_RA(p) != 0 ||
308 DNS_PACKET_AD(p) != 0 ||
309 DNS_PACKET_CD(p) != 0 ||
310 DNS_PACKET_RCODE(p) != 0)
311 return -EBADMSG;
312
313 break;
314
315 default:
316 break;
317 }
318
319 return 1;
320 }
321
322 static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) {
323 assert(p);
324
325 if (p->size + add > p->allocated) {
326 size_t a, ms;
327
328 a = PAGE_ALIGN((p->size + add) * 2);
329
330 ms = dns_packet_size_max(p);
331 if (a > ms)
332 a = ms;
333
334 if (p->size + add > a)
335 return -EMSGSIZE;
336
337 if (p->_data) {
338 void *d;
339
340 d = realloc(p->_data, a);
341 if (!d)
342 return -ENOMEM;
343
344 p->_data = d;
345 } else {
346 p->_data = malloc(a);
347 if (!p->_data)
348 return -ENOMEM;
349
350 memcpy(p->_data, (uint8_t*) p + ALIGN(sizeof(DnsPacket)), p->size);
351 memzero((uint8_t*) p->_data + p->size, a - p->size);
352 }
353
354 p->allocated = a;
355 }
356
357 if (start)
358 *start = p->size;
359
360 if (ret)
361 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->size;
362
363 p->size += add;
364 return 0;
365 }
366
367 void dns_packet_truncate(DnsPacket *p, size_t sz) {
368 Iterator i;
369 char *s;
370 void *n;
371
372 assert(p);
373
374 if (p->size <= sz)
375 return;
376
377 HASHMAP_FOREACH_KEY(n, s, p->names, i) {
378
379 if (PTR_TO_SIZE(n) < sz)
380 continue;
381
382 hashmap_remove(p->names, s);
383 free(s);
384 }
385
386 p->size = sz;
387 }
388
389 int dns_packet_append_blob(DnsPacket *p, const void *d, size_t l, size_t *start) {
390 void *q;
391 int r;
392
393 assert(p);
394
395 r = dns_packet_extend(p, l, &q, start);
396 if (r < 0)
397 return r;
398
399 memcpy(q, d, l);
400 return 0;
401 }
402
403 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start) {
404 void *d;
405 int r;
406
407 assert(p);
408
409 r = dns_packet_extend(p, sizeof(uint8_t), &d, start);
410 if (r < 0)
411 return r;
412
413 ((uint8_t*) d)[0] = v;
414
415 return 0;
416 }
417
418 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) {
419 void *d;
420 int r;
421
422 assert(p);
423
424 r = dns_packet_extend(p, sizeof(uint16_t), &d, start);
425 if (r < 0)
426 return r;
427
428 unaligned_write_be16(d, v);
429
430 return 0;
431 }
432
433 int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
434 void *d;
435 int r;
436
437 assert(p);
438
439 r = dns_packet_extend(p, sizeof(uint32_t), &d, start);
440 if (r < 0)
441 return r;
442
443 unaligned_write_be32(d, v);
444
445 return 0;
446 }
447
448 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) {
449 assert(p);
450 assert(s);
451
452 return dns_packet_append_raw_string(p, s, strlen(s), start);
453 }
454
455 int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start) {
456 void *d;
457 int r;
458
459 assert(p);
460 assert(s || size == 0);
461
462 if (size > 255)
463 return -E2BIG;
464
465 r = dns_packet_extend(p, 1 + size, &d, start);
466 if (r < 0)
467 return r;
468
469 ((uint8_t*) d)[0] = (uint8_t) size;
470
471 memcpy_safe(((uint8_t*) d) + 1, s, size);
472
473 return 0;
474 }
475
476 int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, bool canonical_candidate, size_t *start) {
477 uint8_t *w;
478 int r;
479
480 /* Append a label to a packet. Optionally, does this in DNSSEC
481 * canonical form, if this label is marked as a candidate for
482 * it, and the canonical form logic is enabled for the
483 * packet */
484
485 assert(p);
486 assert(d);
487
488 if (l > DNS_LABEL_MAX)
489 return -E2BIG;
490
491 r = dns_packet_extend(p, 1 + l, (void**) &w, start);
492 if (r < 0)
493 return r;
494
495 *(w++) = (uint8_t) l;
496
497 if (p->canonical_form && canonical_candidate) {
498 size_t i;
499
500 /* Generate in canonical form, as defined by DNSSEC
501 * RFC 4034, Section 6.2, i.e. all lower-case. */
502
503 for (i = 0; i < l; i++)
504 w[i] = (uint8_t) ascii_tolower(d[i]);
505 } else
506 /* Otherwise, just copy the string unaltered. This is
507 * essential for DNS-SD, where the casing of labels
508 * matters and needs to be retained. */
509 memcpy(w, d, l);
510
511 return 0;
512 }
513
514 int dns_packet_append_name(
515 DnsPacket *p,
516 const char *name,
517 bool allow_compression,
518 bool canonical_candidate,
519 size_t *start) {
520
521 size_t saved_size;
522 int r;
523
524 assert(p);
525 assert(name);
526
527 if (p->refuse_compression)
528 allow_compression = false;
529
530 saved_size = p->size;
531
532 while (!dns_name_is_root(name)) {
533 const char *z = name;
534 char label[DNS_LABEL_MAX];
535 size_t n = 0;
536
537 if (allow_compression)
538 n = PTR_TO_SIZE(hashmap_get(p->names, name));
539 if (n > 0) {
540 assert(n < p->size);
541
542 if (n < 0x4000) {
543 r = dns_packet_append_uint16(p, 0xC000 | n, NULL);
544 if (r < 0)
545 goto fail;
546
547 goto done;
548 }
549 }
550
551 r = dns_label_unescape(&name, label, sizeof(label));
552 if (r < 0)
553 goto fail;
554
555 r = dns_packet_append_label(p, label, r, canonical_candidate, &n);
556 if (r < 0)
557 goto fail;
558
559 if (allow_compression) {
560 _cleanup_free_ char *s = NULL;
561
562 s = strdup(z);
563 if (!s) {
564 r = -ENOMEM;
565 goto fail;
566 }
567
568 r = hashmap_ensure_allocated(&p->names, &dns_name_hash_ops);
569 if (r < 0)
570 goto fail;
571
572 r = hashmap_put(p->names, s, SIZE_TO_PTR(n));
573 if (r < 0)
574 goto fail;
575
576 s = NULL;
577 }
578 }
579
580 r = dns_packet_append_uint8(p, 0, NULL);
581 if (r < 0)
582 return r;
583
584 done:
585 if (start)
586 *start = saved_size;
587
588 return 0;
589
590 fail:
591 dns_packet_truncate(p, saved_size);
592 return r;
593 }
594
595 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, const DnsAnswerFlags flags, size_t *start) {
596 size_t saved_size;
597 uint16_t class;
598 int r;
599
600 assert(p);
601 assert(k);
602
603 saved_size = p->size;
604
605 r = dns_packet_append_name(p, dns_resource_key_name(k), true, true, NULL);
606 if (r < 0)
607 goto fail;
608
609 r = dns_packet_append_uint16(p, k->type, NULL);
610 if (r < 0)
611 goto fail;
612
613 class = flags & DNS_ANSWER_CACHE_FLUSH ? k->class | MDNS_RR_CACHE_FLUSH : k->class;
614 r = dns_packet_append_uint16(p, class, NULL);
615 if (r < 0)
616 goto fail;
617
618 if (start)
619 *start = saved_size;
620
621 return 0;
622
623 fail:
624 dns_packet_truncate(p, saved_size);
625 return r;
626 }
627
628 static int dns_packet_append_type_window(DnsPacket *p, uint8_t window, uint8_t length, const uint8_t *types, size_t *start) {
629 size_t saved_size;
630 int r;
631
632 assert(p);
633 assert(types);
634 assert(length > 0);
635
636 saved_size = p->size;
637
638 r = dns_packet_append_uint8(p, window, NULL);
639 if (r < 0)
640 goto fail;
641
642 r = dns_packet_append_uint8(p, length, NULL);
643 if (r < 0)
644 goto fail;
645
646 r = dns_packet_append_blob(p, types, length, NULL);
647 if (r < 0)
648 goto fail;
649
650 if (start)
651 *start = saved_size;
652
653 return 0;
654 fail:
655 dns_packet_truncate(p, saved_size);
656 return r;
657 }
658
659 static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) {
660 Iterator i;
661 uint8_t window = 0;
662 uint8_t entry = 0;
663 uint8_t bitmaps[32] = {};
664 unsigned n;
665 size_t saved_size;
666 int r;
667
668 assert(p);
669
670 saved_size = p->size;
671
672 BITMAP_FOREACH(n, types, i) {
673 assert(n <= 0xffff);
674
675 if ((n >> 8) != window && bitmaps[entry / 8] != 0) {
676 r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
677 if (r < 0)
678 goto fail;
679
680 zero(bitmaps);
681 }
682
683 window = n >> 8;
684 entry = n & 255;
685
686 bitmaps[entry / 8] |= 1 << (7 - (entry % 8));
687 }
688
689 if (bitmaps[entry / 8] != 0) {
690 r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL);
691 if (r < 0)
692 goto fail;
693 }
694
695 if (start)
696 *start = saved_size;
697
698 return 0;
699 fail:
700 dns_packet_truncate(p, saved_size);
701 return r;
702 }
703
704 /* Append the OPT pseudo-RR described in RFC6891 */
705 int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start) {
706 size_t saved_size;
707 int r;
708
709 assert(p);
710 /* we must never advertise supported packet size smaller than the legacy max */
711 assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX);
712 assert(rcode >= 0);
713 assert(rcode <= _DNS_RCODE_MAX);
714
715 if (p->opt_start != (size_t) -1)
716 return -EBUSY;
717
718 assert(p->opt_size == (size_t) -1);
719
720 saved_size = p->size;
721
722 /* empty name */
723 r = dns_packet_append_uint8(p, 0, NULL);
724 if (r < 0)
725 return r;
726
727 /* type */
728 r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL);
729 if (r < 0)
730 goto fail;
731
732 /* class: maximum udp packet that can be received */
733 r = dns_packet_append_uint16(p, max_udp_size, NULL);
734 if (r < 0)
735 goto fail;
736
737 /* extended RCODE and VERSION */
738 r = dns_packet_append_uint16(p, ((uint16_t) rcode & 0x0FF0) << 4, NULL);
739 if (r < 0)
740 goto fail;
741
742 /* flags: DNSSEC OK (DO), see RFC3225 */
743 r = dns_packet_append_uint16(p, edns0_do ? EDNS0_OPT_DO : 0, NULL);
744 if (r < 0)
745 goto fail;
746
747 /* RDLENGTH */
748 if (edns0_do && !DNS_PACKET_QR(p)) {
749 /* If DO is on and this is not a reply, also append RFC6975 Algorithm data */
750
751 static const uint8_t rfc6975[] = {
752
753 0, 5, /* OPTION_CODE: DAU */
754 0, 6, /* LIST_LENGTH */
755 DNSSEC_ALGORITHM_RSASHA1,
756 DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1,
757 DNSSEC_ALGORITHM_RSASHA256,
758 DNSSEC_ALGORITHM_RSASHA512,
759 DNSSEC_ALGORITHM_ECDSAP256SHA256,
760 DNSSEC_ALGORITHM_ECDSAP384SHA384,
761
762 0, 6, /* OPTION_CODE: DHU */
763 0, 3, /* LIST_LENGTH */
764 DNSSEC_DIGEST_SHA1,
765 DNSSEC_DIGEST_SHA256,
766 DNSSEC_DIGEST_SHA384,
767
768 0, 7, /* OPTION_CODE: N3U */
769 0, 1, /* LIST_LENGTH */
770 NSEC3_ALGORITHM_SHA1,
771 };
772
773 r = dns_packet_append_uint16(p, sizeof(rfc6975), NULL);
774 if (r < 0)
775 goto fail;
776
777 r = dns_packet_append_blob(p, rfc6975, sizeof(rfc6975), NULL);
778 } else
779 r = dns_packet_append_uint16(p, 0, NULL);
780 if (r < 0)
781 goto fail;
782
783 DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) + 1);
784
785 p->opt_start = saved_size;
786 p->opt_size = p->size - saved_size;
787
788 if (start)
789 *start = saved_size;
790
791 return 0;
792
793 fail:
794 dns_packet_truncate(p, saved_size);
795 return r;
796 }
797
798 int dns_packet_truncate_opt(DnsPacket *p) {
799 assert(p);
800
801 if (p->opt_start == (size_t) -1) {
802 assert(p->opt_size == (size_t) -1);
803 return 0;
804 }
805
806 assert(p->opt_size != (size_t) -1);
807 assert(DNS_PACKET_ARCOUNT(p) > 0);
808
809 if (p->opt_start + p->opt_size != p->size)
810 return -EBUSY;
811
812 dns_packet_truncate(p, p->opt_start);
813 DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) - 1);
814 p->opt_start = p->opt_size = (size_t) -1;
815
816 return 1;
817 }
818
819 int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start) {
820
821 size_t saved_size, rdlength_offset, end, rdlength, rds;
822 uint32_t ttl;
823 int r;
824
825 assert(p);
826 assert(rr);
827
828 saved_size = p->size;
829
830 r = dns_packet_append_key(p, rr->key, flags, NULL);
831 if (r < 0)
832 goto fail;
833
834 ttl = flags & DNS_ANSWER_GOODBYE ? 0 : rr->ttl;
835 r = dns_packet_append_uint32(p, ttl, NULL);
836 if (r < 0)
837 goto fail;
838
839 /* Initially we write 0 here */
840 r = dns_packet_append_uint16(p, 0, &rdlength_offset);
841 if (r < 0)
842 goto fail;
843
844 rds = p->size - saved_size;
845
846 switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
847
848 case DNS_TYPE_SRV:
849 r = dns_packet_append_uint16(p, rr->srv.priority, NULL);
850 if (r < 0)
851 goto fail;
852
853 r = dns_packet_append_uint16(p, rr->srv.weight, NULL);
854 if (r < 0)
855 goto fail;
856
857 r = dns_packet_append_uint16(p, rr->srv.port, NULL);
858 if (r < 0)
859 goto fail;
860
861 r = dns_packet_append_name(p, rr->srv.name, true, false, NULL);
862 break;
863
864 case DNS_TYPE_PTR:
865 case DNS_TYPE_NS:
866 case DNS_TYPE_CNAME:
867 case DNS_TYPE_DNAME:
868 r = dns_packet_append_name(p, rr->ptr.name, true, false, NULL);
869 break;
870
871 case DNS_TYPE_HINFO:
872 r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
873 if (r < 0)
874 goto fail;
875
876 r = dns_packet_append_string(p, rr->hinfo.os, NULL);
877 break;
878
879 case DNS_TYPE_SPF: /* exactly the same as TXT */
880 case DNS_TYPE_TXT:
881
882 if (!rr->txt.items) {
883 /* RFC 6763, section 6.1 suggests to generate
884 * single empty string for an empty array. */
885
886 r = dns_packet_append_raw_string(p, NULL, 0, NULL);
887 if (r < 0)
888 goto fail;
889 } else {
890 DnsTxtItem *i;
891
892 LIST_FOREACH(items, i, rr->txt.items) {
893 r = dns_packet_append_raw_string(p, i->data, i->length, NULL);
894 if (r < 0)
895 goto fail;
896 }
897 }
898
899 r = 0;
900 break;
901
902 case DNS_TYPE_A:
903 r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
904 break;
905
906 case DNS_TYPE_AAAA:
907 r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
908 break;
909
910 case DNS_TYPE_SOA:
911 r = dns_packet_append_name(p, rr->soa.mname, true, false, NULL);
912 if (r < 0)
913 goto fail;
914
915 r = dns_packet_append_name(p, rr->soa.rname, true, false, NULL);
916 if (r < 0)
917 goto fail;
918
919 r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
920 if (r < 0)
921 goto fail;
922
923 r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
924 if (r < 0)
925 goto fail;
926
927 r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
928 if (r < 0)
929 goto fail;
930
931 r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
932 if (r < 0)
933 goto fail;
934
935 r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
936 break;
937
938 case DNS_TYPE_MX:
939 r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
940 if (r < 0)
941 goto fail;
942
943 r = dns_packet_append_name(p, rr->mx.exchange, true, false, NULL);
944 break;
945
946 case DNS_TYPE_LOC:
947 r = dns_packet_append_uint8(p, rr->loc.version, NULL);
948 if (r < 0)
949 goto fail;
950
951 r = dns_packet_append_uint8(p, rr->loc.size, NULL);
952 if (r < 0)
953 goto fail;
954
955 r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL);
956 if (r < 0)
957 goto fail;
958
959 r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL);
960 if (r < 0)
961 goto fail;
962
963 r = dns_packet_append_uint32(p, rr->loc.latitude, NULL);
964 if (r < 0)
965 goto fail;
966
967 r = dns_packet_append_uint32(p, rr->loc.longitude, NULL);
968 if (r < 0)
969 goto fail;
970
971 r = dns_packet_append_uint32(p, rr->loc.altitude, NULL);
972 break;
973
974 case DNS_TYPE_DS:
975 r = dns_packet_append_uint16(p, rr->ds.key_tag, NULL);
976 if (r < 0)
977 goto fail;
978
979 r = dns_packet_append_uint8(p, rr->ds.algorithm, NULL);
980 if (r < 0)
981 goto fail;
982
983 r = dns_packet_append_uint8(p, rr->ds.digest_type, NULL);
984 if (r < 0)
985 goto fail;
986
987 r = dns_packet_append_blob(p, rr->ds.digest, rr->ds.digest_size, NULL);
988 break;
989
990 case DNS_TYPE_SSHFP:
991 r = dns_packet_append_uint8(p, rr->sshfp.algorithm, NULL);
992 if (r < 0)
993 goto fail;
994
995 r = dns_packet_append_uint8(p, rr->sshfp.fptype, NULL);
996 if (r < 0)
997 goto fail;
998
999 r = dns_packet_append_blob(p, rr->sshfp.fingerprint, rr->sshfp.fingerprint_size, NULL);
1000 break;
1001
1002 case DNS_TYPE_DNSKEY:
1003 r = dns_packet_append_uint16(p, rr->dnskey.flags, NULL);
1004 if (r < 0)
1005 goto fail;
1006
1007 r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL);
1008 if (r < 0)
1009 goto fail;
1010
1011 r = dns_packet_append_uint8(p, rr->dnskey.algorithm, NULL);
1012 if (r < 0)
1013 goto fail;
1014
1015 r = dns_packet_append_blob(p, rr->dnskey.key, rr->dnskey.key_size, NULL);
1016 break;
1017
1018 case DNS_TYPE_RRSIG:
1019 r = dns_packet_append_uint16(p, rr->rrsig.type_covered, NULL);
1020 if (r < 0)
1021 goto fail;
1022
1023 r = dns_packet_append_uint8(p, rr->rrsig.algorithm, NULL);
1024 if (r < 0)
1025 goto fail;
1026
1027 r = dns_packet_append_uint8(p, rr->rrsig.labels, NULL);
1028 if (r < 0)
1029 goto fail;
1030
1031 r = dns_packet_append_uint32(p, rr->rrsig.original_ttl, NULL);
1032 if (r < 0)
1033 goto fail;
1034
1035 r = dns_packet_append_uint32(p, rr->rrsig.expiration, NULL);
1036 if (r < 0)
1037 goto fail;
1038
1039 r = dns_packet_append_uint32(p, rr->rrsig.inception, NULL);
1040 if (r < 0)
1041 goto fail;
1042
1043 r = dns_packet_append_uint16(p, rr->rrsig.key_tag, NULL);
1044 if (r < 0)
1045 goto fail;
1046
1047 r = dns_packet_append_name(p, rr->rrsig.signer, false, true, NULL);
1048 if (r < 0)
1049 goto fail;
1050
1051 r = dns_packet_append_blob(p, rr->rrsig.signature, rr->rrsig.signature_size, NULL);
1052 break;
1053
1054 case DNS_TYPE_NSEC:
1055 r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, false, NULL);
1056 if (r < 0)
1057 goto fail;
1058
1059 r = dns_packet_append_types(p, rr->nsec.types, NULL);
1060 if (r < 0)
1061 goto fail;
1062
1063 break;
1064
1065 case DNS_TYPE_NSEC3:
1066 r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL);
1067 if (r < 0)
1068 goto fail;
1069
1070 r = dns_packet_append_uint8(p, rr->nsec3.flags, NULL);
1071 if (r < 0)
1072 goto fail;
1073
1074 r = dns_packet_append_uint16(p, rr->nsec3.iterations, NULL);
1075 if (r < 0)
1076 goto fail;
1077
1078 r = dns_packet_append_uint8(p, rr->nsec3.salt_size, NULL);
1079 if (r < 0)
1080 goto fail;
1081
1082 r = dns_packet_append_blob(p, rr->nsec3.salt, rr->nsec3.salt_size, NULL);
1083 if (r < 0)
1084 goto fail;
1085
1086 r = dns_packet_append_uint8(p, rr->nsec3.next_hashed_name_size, NULL);
1087 if (r < 0)
1088 goto fail;
1089
1090 r = dns_packet_append_blob(p, rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, NULL);
1091 if (r < 0)
1092 goto fail;
1093
1094 r = dns_packet_append_types(p, rr->nsec3.types, NULL);
1095 if (r < 0)
1096 goto fail;
1097
1098 break;
1099
1100 case DNS_TYPE_TLSA:
1101 r = dns_packet_append_uint8(p, rr->tlsa.cert_usage, NULL);
1102 if (r < 0)
1103 goto fail;
1104
1105 r = dns_packet_append_uint8(p, rr->tlsa.selector, NULL);
1106 if (r < 0)
1107 goto fail;
1108
1109 r = dns_packet_append_uint8(p, rr->tlsa.matching_type, NULL);
1110 if (r < 0)
1111 goto fail;
1112
1113 r = dns_packet_append_blob(p, rr->tlsa.data, rr->tlsa.data_size, NULL);
1114 break;
1115
1116 case DNS_TYPE_CAA:
1117 r = dns_packet_append_uint8(p, rr->caa.flags, NULL);
1118 if (r < 0)
1119 goto fail;
1120
1121 r = dns_packet_append_string(p, rr->caa.tag, NULL);
1122 if (r < 0)
1123 goto fail;
1124
1125 r = dns_packet_append_blob(p, rr->caa.value, rr->caa.value_size, NULL);
1126 break;
1127
1128 case DNS_TYPE_OPT:
1129 case DNS_TYPE_OPENPGPKEY:
1130 case _DNS_TYPE_INVALID: /* unparseable */
1131 default:
1132
1133 r = dns_packet_append_blob(p, rr->generic.data, rr->generic.data_size, NULL);
1134 break;
1135 }
1136 if (r < 0)
1137 goto fail;
1138
1139 /* Let's calculate the actual data size and update the field */
1140 rdlength = p->size - rdlength_offset - sizeof(uint16_t);
1141 if (rdlength > 0xFFFF) {
1142 r = -ENOSPC;
1143 goto fail;
1144 }
1145
1146 end = p->size;
1147 p->size = rdlength_offset;
1148 r = dns_packet_append_uint16(p, rdlength, NULL);
1149 if (r < 0)
1150 goto fail;
1151 p->size = end;
1152
1153 if (start)
1154 *start = saved_size;
1155
1156 if (rdata_start)
1157 *rdata_start = rds;
1158
1159 return 0;
1160
1161 fail:
1162 dns_packet_truncate(p, saved_size);
1163 return r;
1164 }
1165
1166 int dns_packet_append_question(DnsPacket *p, DnsQuestion *q) {
1167 DnsResourceKey *key;
1168 int r;
1169
1170 assert(p);
1171
1172 DNS_QUESTION_FOREACH(key, q) {
1173 r = dns_packet_append_key(p, key, 0, NULL);
1174 if (r < 0)
1175 return r;
1176 }
1177
1178 return 0;
1179 }
1180
1181 int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a) {
1182 DnsResourceRecord *rr;
1183 DnsAnswerFlags flags;
1184 int r;
1185
1186 assert(p);
1187
1188 DNS_ANSWER_FOREACH_FLAGS(rr, flags, a) {
1189 r = dns_packet_append_rr(p, rr, flags, NULL, NULL);
1190 if (r < 0)
1191 return r;
1192 }
1193
1194 return 0;
1195 }
1196
1197 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
1198 assert(p);
1199
1200 if (p->rindex + sz > p->size)
1201 return -EMSGSIZE;
1202
1203 if (ret)
1204 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
1205
1206 if (start)
1207 *start = p->rindex;
1208
1209 p->rindex += sz;
1210 return 0;
1211 }
1212
1213 void dns_packet_rewind(DnsPacket *p, size_t idx) {
1214 assert(p);
1215 assert(idx <= p->size);
1216 assert(idx >= DNS_PACKET_HEADER_SIZE);
1217
1218 p->rindex = idx;
1219 }
1220
1221 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
1222 const void *q;
1223 int r;
1224
1225 assert(p);
1226 assert(d);
1227
1228 r = dns_packet_read(p, sz, &q, start);
1229 if (r < 0)
1230 return r;
1231
1232 memcpy(d, q, sz);
1233 return 0;
1234 }
1235
1236 static int dns_packet_read_memdup(
1237 DnsPacket *p, size_t size,
1238 void **ret, size_t *ret_size,
1239 size_t *ret_start) {
1240
1241 const void *src;
1242 size_t start;
1243 int r;
1244
1245 assert(p);
1246 assert(ret);
1247
1248 r = dns_packet_read(p, size, &src, &start);
1249 if (r < 0)
1250 return r;
1251
1252 if (size <= 0)
1253 *ret = NULL;
1254 else {
1255 void *copy;
1256
1257 copy = memdup(src, size);
1258 if (!copy)
1259 return -ENOMEM;
1260
1261 *ret = copy;
1262 }
1263
1264 if (ret_size)
1265 *ret_size = size;
1266 if (ret_start)
1267 *ret_start = start;
1268
1269 return 0;
1270 }
1271
1272 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
1273 const void *d;
1274 int r;
1275
1276 assert(p);
1277
1278 r = dns_packet_read(p, sizeof(uint8_t), &d, start);
1279 if (r < 0)
1280 return r;
1281
1282 *ret = ((uint8_t*) d)[0];
1283 return 0;
1284 }
1285
1286 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
1287 const void *d;
1288 int r;
1289
1290 assert(p);
1291
1292 r = dns_packet_read(p, sizeof(uint16_t), &d, start);
1293 if (r < 0)
1294 return r;
1295
1296 *ret = unaligned_read_be16(d);
1297
1298 return 0;
1299 }
1300
1301 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
1302 const void *d;
1303 int r;
1304
1305 assert(p);
1306
1307 r = dns_packet_read(p, sizeof(uint32_t), &d, start);
1308 if (r < 0)
1309 return r;
1310
1311 *ret = unaligned_read_be32(d);
1312
1313 return 0;
1314 }
1315
1316 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
1317 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1318 const void *d;
1319 char *t;
1320 uint8_t c;
1321 int r;
1322
1323 assert(p);
1324 INIT_REWINDER(rewinder, p);
1325
1326 r = dns_packet_read_uint8(p, &c, NULL);
1327 if (r < 0)
1328 return r;
1329
1330 r = dns_packet_read(p, c, &d, NULL);
1331 if (r < 0)
1332 return r;
1333
1334 if (memchr(d, 0, c))
1335 return -EBADMSG;
1336
1337 t = strndup(d, c);
1338 if (!t)
1339 return -ENOMEM;
1340
1341 if (!utf8_is_valid(t)) {
1342 free(t);
1343 return -EBADMSG;
1344 }
1345
1346 *ret = t;
1347
1348 if (start)
1349 *start = rewinder.saved_rindex;
1350 CANCEL_REWINDER(rewinder);
1351
1352 return 0;
1353 }
1354
1355 int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) {
1356 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1357 uint8_t c;
1358 int r;
1359
1360 assert(p);
1361 INIT_REWINDER(rewinder, p);
1362
1363 r = dns_packet_read_uint8(p, &c, NULL);
1364 if (r < 0)
1365 return r;
1366
1367 r = dns_packet_read(p, c, ret, NULL);
1368 if (r < 0)
1369 return r;
1370
1371 if (size)
1372 *size = c;
1373 if (start)
1374 *start = rewinder.saved_rindex;
1375 CANCEL_REWINDER(rewinder);
1376
1377 return 0;
1378 }
1379
1380 int dns_packet_read_name(
1381 DnsPacket *p,
1382 char **_ret,
1383 bool allow_compression,
1384 size_t *start) {
1385
1386 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1387 size_t after_rindex = 0, jump_barrier;
1388 _cleanup_free_ char *ret = NULL;
1389 size_t n = 0, allocated = 0;
1390 bool first = true;
1391 int r;
1392
1393 assert(p);
1394 assert(_ret);
1395 INIT_REWINDER(rewinder, p);
1396 jump_barrier = p->rindex;
1397
1398 if (p->refuse_compression)
1399 allow_compression = false;
1400
1401 for (;;) {
1402 uint8_t c, d;
1403
1404 r = dns_packet_read_uint8(p, &c, NULL);
1405 if (r < 0)
1406 return r;
1407
1408 if (c == 0)
1409 /* End of name */
1410 break;
1411 else if (c <= 63) {
1412 const char *label;
1413
1414 /* Literal label */
1415 r = dns_packet_read(p, c, (const void**) &label, NULL);
1416 if (r < 0)
1417 return r;
1418
1419 if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX))
1420 return -ENOMEM;
1421
1422 if (first)
1423 first = false;
1424 else
1425 ret[n++] = '.';
1426
1427 r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX);
1428 if (r < 0)
1429 return r;
1430
1431 n += r;
1432 continue;
1433 } else if (allow_compression && (c & 0xc0) == 0xc0) {
1434 uint16_t ptr;
1435
1436 /* Pointer */
1437 r = dns_packet_read_uint8(p, &d, NULL);
1438 if (r < 0)
1439 return r;
1440
1441 ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
1442 if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= jump_barrier)
1443 return -EBADMSG;
1444
1445 if (after_rindex == 0)
1446 after_rindex = p->rindex;
1447
1448 /* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */
1449 jump_barrier = ptr;
1450 p->rindex = ptr;
1451 } else
1452 return -EBADMSG;
1453 }
1454
1455 if (!GREEDY_REALLOC(ret, allocated, n + 1))
1456 return -ENOMEM;
1457
1458 ret[n] = 0;
1459
1460 if (after_rindex != 0)
1461 p->rindex= after_rindex;
1462
1463 *_ret = ret;
1464 ret = NULL;
1465
1466 if (start)
1467 *start = rewinder.saved_rindex;
1468 CANCEL_REWINDER(rewinder);
1469
1470 return 0;
1471 }
1472
1473 static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *start) {
1474 uint8_t window;
1475 uint8_t length;
1476 const uint8_t *bitmap;
1477 uint8_t bit = 0;
1478 unsigned i;
1479 bool found = false;
1480 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1481 int r;
1482
1483 assert(p);
1484 assert(types);
1485 INIT_REWINDER(rewinder, p);
1486
1487 r = bitmap_ensure_allocated(types);
1488 if (r < 0)
1489 return r;
1490
1491 r = dns_packet_read_uint8(p, &window, NULL);
1492 if (r < 0)
1493 return r;
1494
1495 r = dns_packet_read_uint8(p, &length, NULL);
1496 if (r < 0)
1497 return r;
1498
1499 if (length == 0 || length > 32)
1500 return -EBADMSG;
1501
1502 r = dns_packet_read(p, length, (const void **)&bitmap, NULL);
1503 if (r < 0)
1504 return r;
1505
1506 for (i = 0; i < length; i++) {
1507 uint8_t bitmask = 1 << 7;
1508
1509 if (!bitmap[i]) {
1510 found = false;
1511 bit += 8;
1512 continue;
1513 }
1514
1515 found = true;
1516
1517 while (bitmask) {
1518 if (bitmap[i] & bitmask) {
1519 uint16_t n;
1520
1521 n = (uint16_t) window << 8 | (uint16_t) bit;
1522
1523 /* Ignore pseudo-types. see RFC4034 section 4.1.2 */
1524 if (dns_type_is_pseudo(n))
1525 continue;
1526
1527 r = bitmap_set(*types, n);
1528 if (r < 0)
1529 return r;
1530 }
1531
1532 bit++;
1533 bitmask >>= 1;
1534 }
1535 }
1536
1537 if (!found)
1538 return -EBADMSG;
1539
1540 if (start)
1541 *start = rewinder.saved_rindex;
1542 CANCEL_REWINDER(rewinder);
1543
1544 return 0;
1545 }
1546
1547 static int dns_packet_read_type_windows(DnsPacket *p, Bitmap **types, size_t size, size_t *start) {
1548 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1549 int r;
1550
1551 INIT_REWINDER(rewinder, p);
1552
1553 while (p->rindex < rewinder.saved_rindex + size) {
1554 r = dns_packet_read_type_window(p, types, NULL);
1555 if (r < 0)
1556 return r;
1557
1558 /* don't read past end of current RR */
1559 if (p->rindex > rewinder.saved_rindex + size)
1560 return -EBADMSG;
1561 }
1562
1563 if (p->rindex != rewinder.saved_rindex + size)
1564 return -EBADMSG;
1565
1566 if (start)
1567 *start = rewinder.saved_rindex;
1568 CANCEL_REWINDER(rewinder);
1569
1570 return 0;
1571 }
1572
1573 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start) {
1574 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1575 _cleanup_free_ char *name = NULL;
1576 bool cache_flush = false;
1577 uint16_t class, type;
1578 DnsResourceKey *key;
1579 int r;
1580
1581 assert(p);
1582 assert(ret);
1583 INIT_REWINDER(rewinder, p);
1584
1585 r = dns_packet_read_name(p, &name, true, NULL);
1586 if (r < 0)
1587 return r;
1588
1589 r = dns_packet_read_uint16(p, &type, NULL);
1590 if (r < 0)
1591 return r;
1592
1593 r = dns_packet_read_uint16(p, &class, NULL);
1594 if (r < 0)
1595 return r;
1596
1597 if (p->protocol == DNS_PROTOCOL_MDNS) {
1598 /* See RFC6762, Section 10.2 */
1599
1600 if (type != DNS_TYPE_OPT && (class & MDNS_RR_CACHE_FLUSH)) {
1601 class &= ~MDNS_RR_CACHE_FLUSH;
1602 cache_flush = true;
1603 }
1604 }
1605
1606 key = dns_resource_key_new_consume(class, type, name);
1607 if (!key)
1608 return -ENOMEM;
1609
1610 name = NULL;
1611 *ret = key;
1612
1613 if (ret_cache_flush)
1614 *ret_cache_flush = cache_flush;
1615 if (start)
1616 *start = rewinder.saved_rindex;
1617 CANCEL_REWINDER(rewinder);
1618
1619 return 0;
1620 }
1621
1622 static bool loc_size_ok(uint8_t size) {
1623 uint8_t m = size >> 4, e = size & 0xF;
1624
1625 return m <= 9 && e <= 9 && (m > 0 || e == 0);
1626 }
1627
1628 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, size_t *start) {
1629 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1630 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1631 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder;
1632 size_t offset;
1633 uint16_t rdlength;
1634 bool cache_flush;
1635 int r;
1636
1637 assert(p);
1638 assert(ret);
1639
1640 INIT_REWINDER(rewinder, p);
1641
1642 r = dns_packet_read_key(p, &key, &cache_flush, NULL);
1643 if (r < 0)
1644 return r;
1645
1646 if (!dns_class_is_valid_rr(key->class) || !dns_type_is_valid_rr(key->type))
1647 return -EBADMSG;
1648
1649 rr = dns_resource_record_new(key);
1650 if (!rr)
1651 return -ENOMEM;
1652
1653 r = dns_packet_read_uint32(p, &rr->ttl, NULL);
1654 if (r < 0)
1655 return r;
1656
1657 /* RFC 2181, Section 8, suggests to
1658 * treat a TTL with the MSB set as a zero TTL. */
1659 if (rr->ttl & UINT32_C(0x80000000))
1660 rr->ttl = 0;
1661
1662 r = dns_packet_read_uint16(p, &rdlength, NULL);
1663 if (r < 0)
1664 return r;
1665
1666 if (p->rindex + rdlength > p->size)
1667 return -EBADMSG;
1668
1669 offset = p->rindex;
1670
1671 switch (rr->key->type) {
1672
1673 case DNS_TYPE_SRV:
1674 r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
1675 if (r < 0)
1676 return r;
1677 r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
1678 if (r < 0)
1679 return r;
1680 r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
1681 if (r < 0)
1682 return r;
1683 r = dns_packet_read_name(p, &rr->srv.name, true, NULL);
1684 break;
1685
1686 case DNS_TYPE_PTR:
1687 case DNS_TYPE_NS:
1688 case DNS_TYPE_CNAME:
1689 case DNS_TYPE_DNAME:
1690 r = dns_packet_read_name(p, &rr->ptr.name, true, NULL);
1691 break;
1692
1693 case DNS_TYPE_HINFO:
1694 r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
1695 if (r < 0)
1696 return r;
1697
1698 r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
1699 break;
1700
1701 case DNS_TYPE_SPF: /* exactly the same as TXT */
1702 case DNS_TYPE_TXT:
1703 if (rdlength <= 0) {
1704 DnsTxtItem *i;
1705 /* RFC 6763, section 6.1 suggests to treat
1706 * empty TXT RRs as equivalent to a TXT record
1707 * with a single empty string. */
1708
1709 i = malloc0(offsetof(DnsTxtItem, data) + 1); /* for safety reasons we add an extra NUL byte */
1710 if (!i)
1711 return -ENOMEM;
1712
1713 rr->txt.items = i;
1714 } else {
1715 DnsTxtItem *last = NULL;
1716
1717 while (p->rindex < offset + rdlength) {
1718 DnsTxtItem *i;
1719 const void *data;
1720 size_t sz;
1721
1722 r = dns_packet_read_raw_string(p, &data, &sz, NULL);
1723 if (r < 0)
1724 return r;
1725
1726 i = malloc0(offsetof(DnsTxtItem, data) + sz + 1); /* extra NUL byte at the end */
1727 if (!i)
1728 return -ENOMEM;
1729
1730 memcpy(i->data, data, sz);
1731 i->length = sz;
1732
1733 LIST_INSERT_AFTER(items, rr->txt.items, last, i);
1734 last = i;
1735 }
1736 }
1737
1738 r = 0;
1739 break;
1740
1741 case DNS_TYPE_A:
1742 r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
1743 break;
1744
1745 case DNS_TYPE_AAAA:
1746 r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
1747 break;
1748
1749 case DNS_TYPE_SOA:
1750 r = dns_packet_read_name(p, &rr->soa.mname, true, NULL);
1751 if (r < 0)
1752 return r;
1753
1754 r = dns_packet_read_name(p, &rr->soa.rname, true, NULL);
1755 if (r < 0)
1756 return r;
1757
1758 r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
1759 if (r < 0)
1760 return r;
1761
1762 r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
1763 if (r < 0)
1764 return r;
1765
1766 r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
1767 if (r < 0)
1768 return r;
1769
1770 r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
1771 if (r < 0)
1772 return r;
1773
1774 r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
1775 break;
1776
1777 case DNS_TYPE_MX:
1778 r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
1779 if (r < 0)
1780 return r;
1781
1782 r = dns_packet_read_name(p, &rr->mx.exchange, true, NULL);
1783 break;
1784
1785 case DNS_TYPE_LOC: {
1786 uint8_t t;
1787 size_t pos;
1788
1789 r = dns_packet_read_uint8(p, &t, &pos);
1790 if (r < 0)
1791 return r;
1792
1793 if (t == 0) {
1794 rr->loc.version = t;
1795
1796 r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
1797 if (r < 0)
1798 return r;
1799
1800 if (!loc_size_ok(rr->loc.size))
1801 return -EBADMSG;
1802
1803 r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
1804 if (r < 0)
1805 return r;
1806
1807 if (!loc_size_ok(rr->loc.horiz_pre))
1808 return -EBADMSG;
1809
1810 r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
1811 if (r < 0)
1812 return r;
1813
1814 if (!loc_size_ok(rr->loc.vert_pre))
1815 return -EBADMSG;
1816
1817 r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
1818 if (r < 0)
1819 return r;
1820
1821 r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
1822 if (r < 0)
1823 return r;
1824
1825 r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
1826 if (r < 0)
1827 return r;
1828
1829 break;
1830 } else {
1831 dns_packet_rewind(p, pos);
1832 rr->unparseable = true;
1833 goto unparseable;
1834 }
1835 }
1836
1837 case DNS_TYPE_DS:
1838 r = dns_packet_read_uint16(p, &rr->ds.key_tag, NULL);
1839 if (r < 0)
1840 return r;
1841
1842 r = dns_packet_read_uint8(p, &rr->ds.algorithm, NULL);
1843 if (r < 0)
1844 return r;
1845
1846 r = dns_packet_read_uint8(p, &rr->ds.digest_type, NULL);
1847 if (r < 0)
1848 return r;
1849
1850 r = dns_packet_read_memdup(p, rdlength - 4,
1851 &rr->ds.digest, &rr->ds.digest_size,
1852 NULL);
1853 if (r < 0)
1854 return r;
1855
1856 if (rr->ds.digest_size <= 0)
1857 /* the accepted size depends on the algorithm, but for now
1858 just ensure that the value is greater than zero */
1859 return -EBADMSG;
1860
1861 break;
1862
1863 case DNS_TYPE_SSHFP:
1864 r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
1865 if (r < 0)
1866 return r;
1867
1868 r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL);
1869 if (r < 0)
1870 return r;
1871
1872 r = dns_packet_read_memdup(p, rdlength - 2,
1873 &rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size,
1874 NULL);
1875
1876 if (rr->sshfp.fingerprint_size <= 0)
1877 /* the accepted size depends on the algorithm, but for now
1878 just ensure that the value is greater than zero */
1879 return -EBADMSG;
1880
1881 break;
1882
1883 case DNS_TYPE_DNSKEY:
1884 r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL);
1885 if (r < 0)
1886 return r;
1887
1888 r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL);
1889 if (r < 0)
1890 return r;
1891
1892 r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL);
1893 if (r < 0)
1894 return r;
1895
1896 r = dns_packet_read_memdup(p, rdlength - 4,
1897 &rr->dnskey.key, &rr->dnskey.key_size,
1898 NULL);
1899
1900 if (rr->dnskey.key_size <= 0)
1901 /* the accepted size depends on the algorithm, but for now
1902 just ensure that the value is greater than zero */
1903 return -EBADMSG;
1904
1905 break;
1906
1907 case DNS_TYPE_RRSIG:
1908 r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL);
1909 if (r < 0)
1910 return r;
1911
1912 r = dns_packet_read_uint8(p, &rr->rrsig.algorithm, NULL);
1913 if (r < 0)
1914 return r;
1915
1916 r = dns_packet_read_uint8(p, &rr->rrsig.labels, NULL);
1917 if (r < 0)
1918 return r;
1919
1920 r = dns_packet_read_uint32(p, &rr->rrsig.original_ttl, NULL);
1921 if (r < 0)
1922 return r;
1923
1924 r = dns_packet_read_uint32(p, &rr->rrsig.expiration, NULL);
1925 if (r < 0)
1926 return r;
1927
1928 r = dns_packet_read_uint32(p, &rr->rrsig.inception, NULL);
1929 if (r < 0)
1930 return r;
1931
1932 r = dns_packet_read_uint16(p, &rr->rrsig.key_tag, NULL);
1933 if (r < 0)
1934 return r;
1935
1936 r = dns_packet_read_name(p, &rr->rrsig.signer, false, NULL);
1937 if (r < 0)
1938 return r;
1939
1940 r = dns_packet_read_memdup(p, offset + rdlength - p->rindex,
1941 &rr->rrsig.signature, &rr->rrsig.signature_size,
1942 NULL);
1943
1944 if (rr->rrsig.signature_size <= 0)
1945 /* the accepted size depends on the algorithm, but for now
1946 just ensure that the value is greater than zero */
1947 return -EBADMSG;
1948
1949 break;
1950
1951 case DNS_TYPE_NSEC: {
1952
1953 /*
1954 * RFC6762, section 18.14 explictly states mDNS should use name compression.
1955 * This contradicts RFC3845, section 2.1.1
1956 */
1957
1958 bool allow_compressed = p->protocol == DNS_PROTOCOL_MDNS;
1959
1960 r = dns_packet_read_name(p, &rr->nsec.next_domain_name, allow_compressed, NULL);
1961 if (r < 0)
1962 return r;
1963
1964 r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL);
1965
1966 /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
1967 * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records
1968 * without the NSEC bit set. */
1969
1970 break;
1971 }
1972 case DNS_TYPE_NSEC3: {
1973 uint8_t size;
1974
1975 r = dns_packet_read_uint8(p, &rr->nsec3.algorithm, NULL);
1976 if (r < 0)
1977 return r;
1978
1979 r = dns_packet_read_uint8(p, &rr->nsec3.flags, NULL);
1980 if (r < 0)
1981 return r;
1982
1983 r = dns_packet_read_uint16(p, &rr->nsec3.iterations, NULL);
1984 if (r < 0)
1985 return r;
1986
1987 /* this may be zero */
1988 r = dns_packet_read_uint8(p, &size, NULL);
1989 if (r < 0)
1990 return r;
1991
1992 r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL);
1993 if (r < 0)
1994 return r;
1995
1996 r = dns_packet_read_uint8(p, &size, NULL);
1997 if (r < 0)
1998 return r;
1999
2000 if (size <= 0)
2001 return -EBADMSG;
2002
2003 r = dns_packet_read_memdup(p, size,
2004 &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size,
2005 NULL);
2006 if (r < 0)
2007 return r;
2008
2009 r = dns_packet_read_type_windows(p, &rr->nsec3.types, offset + rdlength - p->rindex, NULL);
2010
2011 /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
2012
2013 break;
2014 }
2015
2016 case DNS_TYPE_TLSA:
2017 r = dns_packet_read_uint8(p, &rr->tlsa.cert_usage, NULL);
2018 if (r < 0)
2019 return r;
2020
2021 r = dns_packet_read_uint8(p, &rr->tlsa.selector, NULL);
2022 if (r < 0)
2023 return r;
2024
2025 r = dns_packet_read_uint8(p, &rr->tlsa.matching_type, NULL);
2026 if (r < 0)
2027 return r;
2028
2029 r = dns_packet_read_memdup(p, rdlength - 3,
2030 &rr->tlsa.data, &rr->tlsa.data_size,
2031 NULL);
2032
2033 if (rr->tlsa.data_size <= 0)
2034 /* the accepted size depends on the algorithm, but for now
2035 just ensure that the value is greater than zero */
2036 return -EBADMSG;
2037
2038 break;
2039
2040 case DNS_TYPE_CAA:
2041 r = dns_packet_read_uint8(p, &rr->caa.flags, NULL);
2042 if (r < 0)
2043 return r;
2044
2045 r = dns_packet_read_string(p, &rr->caa.tag, NULL);
2046 if (r < 0)
2047 return r;
2048
2049 r = dns_packet_read_memdup(p,
2050 rdlength + offset - p->rindex,
2051 &rr->caa.value, &rr->caa.value_size, NULL);
2052
2053 break;
2054
2055 case DNS_TYPE_OPT: /* we only care about the header of OPT for now. */
2056 case DNS_TYPE_OPENPGPKEY:
2057 default:
2058 unparseable:
2059 r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.data_size, NULL);
2060
2061 break;
2062 }
2063 if (r < 0)
2064 return r;
2065 if (p->rindex != offset + rdlength)
2066 return -EBADMSG;
2067
2068 *ret = rr;
2069 rr = NULL;
2070
2071 if (ret_cache_flush)
2072 *ret_cache_flush = cache_flush;
2073 if (start)
2074 *start = rewinder.saved_rindex;
2075 CANCEL_REWINDER(rewinder);
2076
2077 return 0;
2078 }
2079
2080 static bool opt_is_good(DnsResourceRecord *rr, bool *rfc6975) {
2081 const uint8_t* p;
2082 bool found_dau_dhu_n3u = false;
2083 size_t l;
2084
2085 /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in
2086 * a reply). */
2087
2088 assert(rr);
2089 assert(rr->key->type == DNS_TYPE_OPT);
2090
2091 /* Check that the version is 0 */
2092 if (((rr->ttl >> 16) & UINT32_C(0xFF)) != 0) {
2093 *rfc6975 = false;
2094 return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */
2095 }
2096
2097 p = rr->opt.data;
2098 l = rr->opt.data_size;
2099 while (l > 0) {
2100 uint16_t option_code, option_length;
2101
2102 /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */
2103 if (l < 4U)
2104 return false;
2105
2106 option_code = unaligned_read_be16(p);
2107 option_length = unaligned_read_be16(p + 2);
2108
2109 if (l < option_length + 4U)
2110 return false;
2111
2112 /* RFC 6975 DAU, DHU or N3U fields found. */
2113 if (IN_SET(option_code, 5, 6, 7))
2114 found_dau_dhu_n3u = true;
2115
2116 p += option_length + 4U;
2117 l -= option_length + 4U;
2118 }
2119
2120 *rfc6975 = found_dau_dhu_n3u;
2121 return true;
2122 }
2123
2124 int dns_packet_extract(DnsPacket *p) {
2125 _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
2126 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
2127 _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {};
2128 unsigned n, i;
2129 int r;
2130
2131 if (p->extracted)
2132 return 0;
2133
2134 INIT_REWINDER(rewinder, p);
2135 dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
2136
2137 n = DNS_PACKET_QDCOUNT(p);
2138 if (n > 0) {
2139 question = dns_question_new(n);
2140 if (!question)
2141 return -ENOMEM;
2142
2143 for (i = 0; i < n; i++) {
2144 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
2145 bool cache_flush;
2146
2147 r = dns_packet_read_key(p, &key, &cache_flush, NULL);
2148 if (r < 0)
2149 return r;
2150
2151 if (cache_flush)
2152 return -EBADMSG;
2153
2154 if (!dns_type_is_valid_query(key->type))
2155 return -EBADMSG;
2156
2157 r = dns_question_add(question, key);
2158 if (r < 0)
2159 return r;
2160 }
2161 }
2162
2163 n = DNS_PACKET_RRCOUNT(p);
2164 if (n > 0) {
2165 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL;
2166 bool bad_opt = false;
2167
2168 answer = dns_answer_new(n);
2169 if (!answer)
2170 return -ENOMEM;
2171
2172 for (i = 0; i < n; i++) {
2173 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
2174 bool cache_flush = false;
2175
2176 r = dns_packet_read_rr(p, &rr, &cache_flush, NULL);
2177 if (r < 0)
2178 return r;
2179
2180 /* Try to reduce memory usage a bit */
2181 if (previous)
2182 dns_resource_key_reduce(&rr->key, &previous->key);
2183
2184 if (rr->key->type == DNS_TYPE_OPT) {
2185 bool has_rfc6975;
2186
2187 if (p->opt || bad_opt) {
2188 /* Multiple OPT RRs? if so, let's ignore all, because there's something wrong
2189 * with the server, and if one is valid we wouldn't know which one. */
2190 log_debug("Multiple OPT RRs detected, ignoring all.");
2191 bad_opt = true;
2192 continue;
2193 }
2194
2195 if (!dns_name_is_root(dns_resource_key_name(rr->key))) {
2196 /* If the OPT RR is not owned by the root domain, then it is bad, let's ignore
2197 * it. */
2198 log_debug("OPT RR is not owned by root domain, ignoring.");
2199 bad_opt = true;
2200 continue;
2201 }
2202
2203 if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) {
2204 /* OPT RR is in the wrong section? Some Belkin routers do this. This is a hint
2205 * the EDNS implementation is borked, like the Belkin one is, hence ignore
2206 * it. */
2207 log_debug("OPT RR in wrong section, ignoring.");
2208 bad_opt = true;
2209 continue;
2210 }
2211
2212 if (!opt_is_good(rr, &has_rfc6975)) {
2213 log_debug("Malformed OPT RR, ignoring.");
2214 bad_opt = true;
2215 continue;
2216 }
2217
2218 if (DNS_PACKET_QR(p)) {
2219 /* Additional checks for responses */
2220
2221 if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) {
2222 /* If this is a reply and we don't know the EDNS version then something
2223 * is weird... */
2224 log_debug("EDNS version newer that our request, bad server.");
2225 return -EBADMSG;
2226 }
2227
2228 if (has_rfc6975) {
2229 /* If the OPT RR contains RFC6975 algorithm data, then this is indication that
2230 * the server just copied the OPT it got from us (which contained that data)
2231 * back into the reply. If so, then it doesn't properly support EDNS, as
2232 * RFC6975 makes it very clear that the algorithm data should only be contained
2233 * in questions, never in replies. Crappy Belkin routers copy the OPT data for
2234 * example, hence let's detect this so that we downgrade early. */
2235 log_debug("OPT RR contained RFC6975 data, ignoring.");
2236 bad_opt = true;
2237 continue;
2238 }
2239 }
2240
2241 p->opt = dns_resource_record_ref(rr);
2242 } else {
2243
2244 /* According to RFC 4795, section 2.9. only the RRs from the Answer section shall be
2245 * cached. Hence mark only those RRs as cacheable by default, but not the ones from the
2246 * Additional or Authority sections. */
2247
2248 r = dns_answer_add(answer, rr, p->ifindex,
2249 (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) |
2250 (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0));
2251 if (r < 0)
2252 return r;
2253 }
2254
2255 /* Remember this RR, so that we potentically can merge it's ->key object with the next RR. Note
2256 * that we only do this if we actually decided to keep the RR around. */
2257 dns_resource_record_unref(previous);
2258 previous = dns_resource_record_ref(rr);
2259 }
2260
2261 if (bad_opt)
2262 p->opt = dns_resource_record_unref(p->opt);
2263 }
2264
2265 p->question = question;
2266 question = NULL;
2267
2268 p->answer = answer;
2269 answer = NULL;
2270
2271 p->extracted = true;
2272
2273 /* no CANCEL, always rewind */
2274 return 0;
2275 }
2276
2277 int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) {
2278 int r;
2279
2280 assert(p);
2281 assert(key);
2282
2283 /* Checks if the specified packet is a reply for the specified
2284 * key and the specified key is the only one in the question
2285 * section. */
2286
2287 if (DNS_PACKET_QR(p) != 1)
2288 return 0;
2289
2290 /* Let's unpack the packet, if that hasn't happened yet. */
2291 r = dns_packet_extract(p);
2292 if (r < 0)
2293 return r;
2294
2295 if (!p->question)
2296 return 0;
2297
2298 if (p->question->n_keys != 1)
2299 return 0;
2300
2301 return dns_resource_key_equal(p->question->keys[0], key);
2302 }
2303
2304 static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
2305 [DNS_RCODE_SUCCESS] = "SUCCESS",
2306 [DNS_RCODE_FORMERR] = "FORMERR",
2307 [DNS_RCODE_SERVFAIL] = "SERVFAIL",
2308 [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
2309 [DNS_RCODE_NOTIMP] = "NOTIMP",
2310 [DNS_RCODE_REFUSED] = "REFUSED",
2311 [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
2312 [DNS_RCODE_YXRRSET] = "YRRSET",
2313 [DNS_RCODE_NXRRSET] = "NXRRSET",
2314 [DNS_RCODE_NOTAUTH] = "NOTAUTH",
2315 [DNS_RCODE_NOTZONE] = "NOTZONE",
2316 [DNS_RCODE_BADVERS] = "BADVERS",
2317 [DNS_RCODE_BADKEY] = "BADKEY",
2318 [DNS_RCODE_BADTIME] = "BADTIME",
2319 [DNS_RCODE_BADMODE] = "BADMODE",
2320 [DNS_RCODE_BADNAME] = "BADNAME",
2321 [DNS_RCODE_BADALG] = "BADALG",
2322 [DNS_RCODE_BADTRUNC] = "BADTRUNC",
2323 [DNS_RCODE_BADCOOKIE] = "BADCOOKIE",
2324 };
2325 DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
2326
2327 static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
2328 [DNS_PROTOCOL_DNS] = "dns",
2329 [DNS_PROTOCOL_MDNS] = "mdns",
2330 [DNS_PROTOCOL_LLMNR] = "llmnr",
2331 };
2332 DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);
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