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1 | /* SPDX-License-Identifier: LGPL-2.1+ */ | |
2 | ||
3 | #if HAVE_GCRYPT | |
4 | #include <gcrypt.h> | |
5 | #endif | |
6 | ||
7 | #include "alloc-util.h" | |
8 | #include "dns-domain.h" | |
9 | #include "memory-util.h" | |
10 | #include "resolved-dns-packet.h" | |
11 | #include "set.h" | |
12 | #include "string-table.h" | |
13 | #include "strv.h" | |
14 | #include "unaligned.h" | |
15 | #include "utf8.h" | |
16 | #include "util.h" | |
17 | ||
18 | #define EDNS0_OPT_DO (1<<15) | |
19 | ||
20 | assert_cc(DNS_PACKET_SIZE_START > DNS_PACKET_HEADER_SIZE) | |
21 | ||
22 | typedef struct DnsPacketRewinder { | |
23 | DnsPacket *packet; | |
24 | size_t saved_rindex; | |
25 | } DnsPacketRewinder; | |
26 | ||
27 | static void rewind_dns_packet(DnsPacketRewinder *rewinder) { | |
28 | if (rewinder->packet) | |
29 | dns_packet_rewind(rewinder->packet, rewinder->saved_rindex); | |
30 | } | |
31 | ||
32 | #define INIT_REWINDER(rewinder, p) do { rewinder.packet = p; rewinder.saved_rindex = p->rindex; } while (0) | |
33 | #define CANCEL_REWINDER(rewinder) do { rewinder.packet = NULL; } while (0) | |
34 | ||
35 | int dns_packet_new( | |
36 | DnsPacket **ret, | |
37 | DnsProtocol protocol, | |
38 | size_t min_alloc_dsize, | |
39 | size_t max_size) { | |
40 | ||
41 | DnsPacket *p; | |
42 | size_t a; | |
43 | ||
44 | assert(ret); | |
45 | assert(max_size >= DNS_PACKET_HEADER_SIZE); | |
46 | ||
47 | if (max_size > DNS_PACKET_SIZE_MAX) | |
48 | max_size = DNS_PACKET_SIZE_MAX; | |
49 | ||
50 | /* The caller may not check what is going to be truly allocated, so do not allow to | |
51 | * allocate a DNS packet bigger than DNS_PACKET_SIZE_MAX. | |
52 | */ | |
53 | if (min_alloc_dsize > DNS_PACKET_SIZE_MAX) | |
54 | return log_error_errno(SYNTHETIC_ERRNO(EFBIG), | |
55 | "Requested packet data size too big: %zu", | |
56 | min_alloc_dsize); | |
57 | ||
58 | /* When dns_packet_new() is called with min_alloc_dsize == 0, allocate more than the | |
59 | * absolute minimum (which is the dns packet header size), to avoid | |
60 | * resizing immediately again after appending the first data to the packet. | |
61 | */ | |
62 | if (min_alloc_dsize < DNS_PACKET_HEADER_SIZE) | |
63 | a = DNS_PACKET_SIZE_START; | |
64 | else | |
65 | a = min_alloc_dsize; | |
66 | ||
67 | /* round up to next page size */ | |
68 | a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket)); | |
69 | ||
70 | /* make sure we never allocate more than useful */ | |
71 | if (a > max_size) | |
72 | a = max_size; | |
73 | ||
74 | p = malloc0(ALIGN(sizeof(DnsPacket)) + a); | |
75 | if (!p) | |
76 | return -ENOMEM; | |
77 | ||
78 | p->size = p->rindex = DNS_PACKET_HEADER_SIZE; | |
79 | p->allocated = a; | |
80 | p->max_size = max_size; | |
81 | p->protocol = protocol; | |
82 | p->opt_start = p->opt_size = (size_t) -1; | |
83 | p->n_ref = 1; | |
84 | ||
85 | *ret = p; | |
86 | ||
87 | return 0; | |
88 | } | |
89 | ||
90 | void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated) { | |
91 | ||
92 | DnsPacketHeader *h; | |
93 | ||
94 | assert(p); | |
95 | ||
96 | h = DNS_PACKET_HEADER(p); | |
97 | ||
98 | switch(p->protocol) { | |
99 | case DNS_PROTOCOL_LLMNR: | |
100 | assert(!truncated); | |
101 | ||
102 | h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, | |
103 | 0 /* opcode */, | |
104 | 0 /* c */, | |
105 | 0 /* tc */, | |
106 | 0 /* t */, | |
107 | 0 /* ra */, | |
108 | 0 /* ad */, | |
109 | 0 /* cd */, | |
110 | 0 /* rcode */)); | |
111 | break; | |
112 | ||
113 | case DNS_PROTOCOL_MDNS: | |
114 | h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, | |
115 | 0 /* opcode */, | |
116 | 0 /* aa */, | |
117 | truncated /* tc */, | |
118 | 0 /* rd (ask for recursion) */, | |
119 | 0 /* ra */, | |
120 | 0 /* ad */, | |
121 | 0 /* cd */, | |
122 | 0 /* rcode */)); | |
123 | break; | |
124 | ||
125 | default: | |
126 | assert(!truncated); | |
127 | ||
128 | h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */, | |
129 | 0 /* opcode */, | |
130 | 0 /* aa */, | |
131 | 0 /* tc */, | |
132 | 1 /* rd (ask for recursion) */, | |
133 | 0 /* ra */, | |
134 | 0 /* ad */, | |
135 | dnssec_checking_disabled /* cd */, | |
136 | 0 /* rcode */)); | |
137 | } | |
138 | } | |
139 | ||
140 | int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled) { | |
141 | DnsPacket *p; | |
142 | int r; | |
143 | ||
144 | assert(ret); | |
145 | ||
146 | r = dns_packet_new(&p, protocol, min_alloc_dsize, DNS_PACKET_SIZE_MAX); | |
147 | if (r < 0) | |
148 | return r; | |
149 | ||
150 | /* Always set the TC bit to 0 initially. | |
151 | * If there are multiple packets later, we'll update the bit shortly before sending. | |
152 | */ | |
153 | dns_packet_set_flags(p, dnssec_checking_disabled, false); | |
154 | ||
155 | *ret = p; | |
156 | return 0; | |
157 | } | |
158 | ||
159 | DnsPacket *dns_packet_ref(DnsPacket *p) { | |
160 | ||
161 | if (!p) | |
162 | return NULL; | |
163 | ||
164 | assert(!p->on_stack); | |
165 | ||
166 | assert(p->n_ref > 0); | |
167 | p->n_ref++; | |
168 | return p; | |
169 | } | |
170 | ||
171 | static void dns_packet_free(DnsPacket *p) { | |
172 | char *s; | |
173 | ||
174 | assert(p); | |
175 | ||
176 | dns_question_unref(p->question); | |
177 | dns_answer_unref(p->answer); | |
178 | dns_resource_record_unref(p->opt); | |
179 | ||
180 | while ((s = hashmap_steal_first_key(p->names))) | |
181 | free(s); | |
182 | hashmap_free(p->names); | |
183 | ||
184 | free(p->_data); | |
185 | ||
186 | if (!p->on_stack) | |
187 | free(p); | |
188 | } | |
189 | ||
190 | DnsPacket *dns_packet_unref(DnsPacket *p) { | |
191 | if (!p) | |
192 | return NULL; | |
193 | ||
194 | assert(p->n_ref > 0); | |
195 | ||
196 | dns_packet_unref(p->more); | |
197 | ||
198 | if (p->n_ref == 1) | |
199 | dns_packet_free(p); | |
200 | else | |
201 | p->n_ref--; | |
202 | ||
203 | return NULL; | |
204 | } | |
205 | ||
206 | int dns_packet_validate(DnsPacket *p) { | |
207 | assert(p); | |
208 | ||
209 | if (p->size < DNS_PACKET_HEADER_SIZE) | |
210 | return -EBADMSG; | |
211 | ||
212 | if (p->size > DNS_PACKET_SIZE_MAX) | |
213 | return -EBADMSG; | |
214 | ||
215 | return 1; | |
216 | } | |
217 | ||
218 | int dns_packet_validate_reply(DnsPacket *p) { | |
219 | int r; | |
220 | ||
221 | assert(p); | |
222 | ||
223 | r = dns_packet_validate(p); | |
224 | if (r < 0) | |
225 | return r; | |
226 | ||
227 | if (DNS_PACKET_QR(p) != 1) | |
228 | return 0; | |
229 | ||
230 | if (DNS_PACKET_OPCODE(p) != 0) | |
231 | return -EBADMSG; | |
232 | ||
233 | switch (p->protocol) { | |
234 | ||
235 | case DNS_PROTOCOL_LLMNR: | |
236 | /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */ | |
237 | if (DNS_PACKET_QDCOUNT(p) != 1) | |
238 | return -EBADMSG; | |
239 | ||
240 | break; | |
241 | ||
242 | case DNS_PROTOCOL_MDNS: | |
243 | /* RFC 6762, Section 18 */ | |
244 | if (DNS_PACKET_RCODE(p) != 0) | |
245 | return -EBADMSG; | |
246 | ||
247 | break; | |
248 | ||
249 | default: | |
250 | break; | |
251 | } | |
252 | ||
253 | return 1; | |
254 | } | |
255 | ||
256 | int dns_packet_validate_query(DnsPacket *p) { | |
257 | int r; | |
258 | ||
259 | assert(p); | |
260 | ||
261 | r = dns_packet_validate(p); | |
262 | if (r < 0) | |
263 | return r; | |
264 | ||
265 | if (DNS_PACKET_QR(p) != 0) | |
266 | return 0; | |
267 | ||
268 | if (DNS_PACKET_OPCODE(p) != 0) | |
269 | return -EBADMSG; | |
270 | ||
271 | if (DNS_PACKET_TC(p)) | |
272 | return -EBADMSG; | |
273 | ||
274 | switch (p->protocol) { | |
275 | ||
276 | case DNS_PROTOCOL_LLMNR: | |
277 | case DNS_PROTOCOL_DNS: | |
278 | /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */ | |
279 | if (DNS_PACKET_QDCOUNT(p) != 1) | |
280 | return -EBADMSG; | |
281 | ||
282 | /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */ | |
283 | if (DNS_PACKET_ANCOUNT(p) > 0) | |
284 | return -EBADMSG; | |
285 | ||
286 | /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */ | |
287 | if (DNS_PACKET_NSCOUNT(p) > 0) | |
288 | return -EBADMSG; | |
289 | ||
290 | break; | |
291 | ||
292 | case DNS_PROTOCOL_MDNS: | |
293 | /* RFC 6762, Section 18 */ | |
294 | if (DNS_PACKET_AA(p) != 0 || | |
295 | DNS_PACKET_RD(p) != 0 || | |
296 | DNS_PACKET_RA(p) != 0 || | |
297 | DNS_PACKET_AD(p) != 0 || | |
298 | DNS_PACKET_CD(p) != 0 || | |
299 | DNS_PACKET_RCODE(p) != 0) | |
300 | return -EBADMSG; | |
301 | ||
302 | break; | |
303 | ||
304 | default: | |
305 | break; | |
306 | } | |
307 | ||
308 | return 1; | |
309 | } | |
310 | ||
311 | static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) { | |
312 | assert(p); | |
313 | ||
314 | if (p->size + add > p->allocated) { | |
315 | size_t a, ms; | |
316 | ||
317 | a = PAGE_ALIGN((p->size + add) * 2); | |
318 | ||
319 | ms = dns_packet_size_max(p); | |
320 | if (a > ms) | |
321 | a = ms; | |
322 | ||
323 | if (p->size + add > a) | |
324 | return -EMSGSIZE; | |
325 | ||
326 | if (p->_data) { | |
327 | void *d; | |
328 | ||
329 | d = realloc(p->_data, a); | |
330 | if (!d) | |
331 | return -ENOMEM; | |
332 | ||
333 | p->_data = d; | |
334 | } else { | |
335 | p->_data = malloc(a); | |
336 | if (!p->_data) | |
337 | return -ENOMEM; | |
338 | ||
339 | memcpy(p->_data, (uint8_t*) p + ALIGN(sizeof(DnsPacket)), p->size); | |
340 | memzero((uint8_t*) p->_data + p->size, a - p->size); | |
341 | } | |
342 | ||
343 | p->allocated = a; | |
344 | } | |
345 | ||
346 | if (start) | |
347 | *start = p->size; | |
348 | ||
349 | if (ret) | |
350 | *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->size; | |
351 | ||
352 | p->size += add; | |
353 | return 0; | |
354 | } | |
355 | ||
356 | void dns_packet_truncate(DnsPacket *p, size_t sz) { | |
357 | Iterator i; | |
358 | char *s; | |
359 | void *n; | |
360 | ||
361 | assert(p); | |
362 | ||
363 | if (p->size <= sz) | |
364 | return; | |
365 | ||
366 | HASHMAP_FOREACH_KEY(n, s, p->names, i) { | |
367 | ||
368 | if (PTR_TO_SIZE(n) < sz) | |
369 | continue; | |
370 | ||
371 | hashmap_remove(p->names, s); | |
372 | free(s); | |
373 | } | |
374 | ||
375 | p->size = sz; | |
376 | } | |
377 | ||
378 | int dns_packet_append_blob(DnsPacket *p, const void *d, size_t l, size_t *start) { | |
379 | void *q; | |
380 | int r; | |
381 | ||
382 | assert(p); | |
383 | ||
384 | r = dns_packet_extend(p, l, &q, start); | |
385 | if (r < 0) | |
386 | return r; | |
387 | ||
388 | memcpy_safe(q, d, l); | |
389 | return 0; | |
390 | } | |
391 | ||
392 | int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start) { | |
393 | void *d; | |
394 | int r; | |
395 | ||
396 | assert(p); | |
397 | ||
398 | r = dns_packet_extend(p, sizeof(uint8_t), &d, start); | |
399 | if (r < 0) | |
400 | return r; | |
401 | ||
402 | ((uint8_t*) d)[0] = v; | |
403 | ||
404 | return 0; | |
405 | } | |
406 | ||
407 | int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) { | |
408 | void *d; | |
409 | int r; | |
410 | ||
411 | assert(p); | |
412 | ||
413 | r = dns_packet_extend(p, sizeof(uint16_t), &d, start); | |
414 | if (r < 0) | |
415 | return r; | |
416 | ||
417 | unaligned_write_be16(d, v); | |
418 | ||
419 | return 0; | |
420 | } | |
421 | ||
422 | int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) { | |
423 | void *d; | |
424 | int r; | |
425 | ||
426 | assert(p); | |
427 | ||
428 | r = dns_packet_extend(p, sizeof(uint32_t), &d, start); | |
429 | if (r < 0) | |
430 | return r; | |
431 | ||
432 | unaligned_write_be32(d, v); | |
433 | ||
434 | return 0; | |
435 | } | |
436 | ||
437 | int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) { | |
438 | assert(p); | |
439 | assert(s); | |
440 | ||
441 | return dns_packet_append_raw_string(p, s, strlen(s), start); | |
442 | } | |
443 | ||
444 | int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start) { | |
445 | void *d; | |
446 | int r; | |
447 | ||
448 | assert(p); | |
449 | assert(s || size == 0); | |
450 | ||
451 | if (size > 255) | |
452 | return -E2BIG; | |
453 | ||
454 | r = dns_packet_extend(p, 1 + size, &d, start); | |
455 | if (r < 0) | |
456 | return r; | |
457 | ||
458 | ((uint8_t*) d)[0] = (uint8_t) size; | |
459 | ||
460 | memcpy_safe(((uint8_t*) d) + 1, s, size); | |
461 | ||
462 | return 0; | |
463 | } | |
464 | ||
465 | int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, bool canonical_candidate, size_t *start) { | |
466 | uint8_t *w; | |
467 | int r; | |
468 | ||
469 | /* Append a label to a packet. Optionally, does this in DNSSEC | |
470 | * canonical form, if this label is marked as a candidate for | |
471 | * it, and the canonical form logic is enabled for the | |
472 | * packet */ | |
473 | ||
474 | assert(p); | |
475 | assert(d); | |
476 | ||
477 | if (l > DNS_LABEL_MAX) | |
478 | return -E2BIG; | |
479 | ||
480 | r = dns_packet_extend(p, 1 + l, (void**) &w, start); | |
481 | if (r < 0) | |
482 | return r; | |
483 | ||
484 | *(w++) = (uint8_t) l; | |
485 | ||
486 | if (p->canonical_form && canonical_candidate) { | |
487 | size_t i; | |
488 | ||
489 | /* Generate in canonical form, as defined by DNSSEC | |
490 | * RFC 4034, Section 6.2, i.e. all lower-case. */ | |
491 | ||
492 | for (i = 0; i < l; i++) | |
493 | w[i] = (uint8_t) ascii_tolower(d[i]); | |
494 | } else | |
495 | /* Otherwise, just copy the string unaltered. This is | |
496 | * essential for DNS-SD, where the casing of labels | |
497 | * matters and needs to be retained. */ | |
498 | memcpy(w, d, l); | |
499 | ||
500 | return 0; | |
501 | } | |
502 | ||
503 | int dns_packet_append_name( | |
504 | DnsPacket *p, | |
505 | const char *name, | |
506 | bool allow_compression, | |
507 | bool canonical_candidate, | |
508 | size_t *start) { | |
509 | ||
510 | size_t saved_size; | |
511 | int r; | |
512 | ||
513 | assert(p); | |
514 | assert(name); | |
515 | ||
516 | if (p->refuse_compression) | |
517 | allow_compression = false; | |
518 | ||
519 | saved_size = p->size; | |
520 | ||
521 | while (!dns_name_is_root(name)) { | |
522 | const char *z = name; | |
523 | char label[DNS_LABEL_MAX]; | |
524 | size_t n = 0; | |
525 | ||
526 | if (allow_compression) | |
527 | n = PTR_TO_SIZE(hashmap_get(p->names, name)); | |
528 | if (n > 0) { | |
529 | assert(n < p->size); | |
530 | ||
531 | if (n < 0x4000) { | |
532 | r = dns_packet_append_uint16(p, 0xC000 | n, NULL); | |
533 | if (r < 0) | |
534 | goto fail; | |
535 | ||
536 | goto done; | |
537 | } | |
538 | } | |
539 | ||
540 | r = dns_label_unescape(&name, label, sizeof label, 0); | |
541 | if (r < 0) | |
542 | goto fail; | |
543 | ||
544 | r = dns_packet_append_label(p, label, r, canonical_candidate, &n); | |
545 | if (r < 0) | |
546 | goto fail; | |
547 | ||
548 | if (allow_compression) { | |
549 | _cleanup_free_ char *s = NULL; | |
550 | ||
551 | s = strdup(z); | |
552 | if (!s) { | |
553 | r = -ENOMEM; | |
554 | goto fail; | |
555 | } | |
556 | ||
557 | r = hashmap_ensure_allocated(&p->names, &dns_name_hash_ops); | |
558 | if (r < 0) | |
559 | goto fail; | |
560 | ||
561 | r = hashmap_put(p->names, s, SIZE_TO_PTR(n)); | |
562 | if (r < 0) | |
563 | goto fail; | |
564 | ||
565 | s = NULL; | |
566 | } | |
567 | } | |
568 | ||
569 | r = dns_packet_append_uint8(p, 0, NULL); | |
570 | if (r < 0) | |
571 | return r; | |
572 | ||
573 | done: | |
574 | if (start) | |
575 | *start = saved_size; | |
576 | ||
577 | return 0; | |
578 | ||
579 | fail: | |
580 | dns_packet_truncate(p, saved_size); | |
581 | return r; | |
582 | } | |
583 | ||
584 | int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, const DnsAnswerFlags flags, size_t *start) { | |
585 | size_t saved_size; | |
586 | uint16_t class; | |
587 | int r; | |
588 | ||
589 | assert(p); | |
590 | assert(k); | |
591 | ||
592 | saved_size = p->size; | |
593 | ||
594 | r = dns_packet_append_name(p, dns_resource_key_name(k), true, true, NULL); | |
595 | if (r < 0) | |
596 | goto fail; | |
597 | ||
598 | r = dns_packet_append_uint16(p, k->type, NULL); | |
599 | if (r < 0) | |
600 | goto fail; | |
601 | ||
602 | class = flags & DNS_ANSWER_CACHE_FLUSH ? k->class | MDNS_RR_CACHE_FLUSH : k->class; | |
603 | r = dns_packet_append_uint16(p, class, NULL); | |
604 | if (r < 0) | |
605 | goto fail; | |
606 | ||
607 | if (start) | |
608 | *start = saved_size; | |
609 | ||
610 | return 0; | |
611 | ||
612 | fail: | |
613 | dns_packet_truncate(p, saved_size); | |
614 | return r; | |
615 | } | |
616 | ||
617 | static int dns_packet_append_type_window(DnsPacket *p, uint8_t window, uint8_t length, const uint8_t *types, size_t *start) { | |
618 | size_t saved_size; | |
619 | int r; | |
620 | ||
621 | assert(p); | |
622 | assert(types); | |
623 | assert(length > 0); | |
624 | ||
625 | saved_size = p->size; | |
626 | ||
627 | r = dns_packet_append_uint8(p, window, NULL); | |
628 | if (r < 0) | |
629 | goto fail; | |
630 | ||
631 | r = dns_packet_append_uint8(p, length, NULL); | |
632 | if (r < 0) | |
633 | goto fail; | |
634 | ||
635 | r = dns_packet_append_blob(p, types, length, NULL); | |
636 | if (r < 0) | |
637 | goto fail; | |
638 | ||
639 | if (start) | |
640 | *start = saved_size; | |
641 | ||
642 | return 0; | |
643 | fail: | |
644 | dns_packet_truncate(p, saved_size); | |
645 | return r; | |
646 | } | |
647 | ||
648 | static int dns_packet_append_types(DnsPacket *p, Bitmap *types, size_t *start) { | |
649 | Iterator i; | |
650 | uint8_t window = 0; | |
651 | uint8_t entry = 0; | |
652 | uint8_t bitmaps[32] = {}; | |
653 | unsigned n; | |
654 | size_t saved_size; | |
655 | int r; | |
656 | ||
657 | assert(p); | |
658 | ||
659 | saved_size = p->size; | |
660 | ||
661 | BITMAP_FOREACH(n, types, i) { | |
662 | assert(n <= 0xffff); | |
663 | ||
664 | if ((n >> 8) != window && bitmaps[entry / 8] != 0) { | |
665 | r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL); | |
666 | if (r < 0) | |
667 | goto fail; | |
668 | ||
669 | zero(bitmaps); | |
670 | } | |
671 | ||
672 | window = n >> 8; | |
673 | entry = n & 255; | |
674 | ||
675 | bitmaps[entry / 8] |= 1 << (7 - (entry % 8)); | |
676 | } | |
677 | ||
678 | if (bitmaps[entry / 8] != 0) { | |
679 | r = dns_packet_append_type_window(p, window, entry / 8 + 1, bitmaps, NULL); | |
680 | if (r < 0) | |
681 | goto fail; | |
682 | } | |
683 | ||
684 | if (start) | |
685 | *start = saved_size; | |
686 | ||
687 | return 0; | |
688 | fail: | |
689 | dns_packet_truncate(p, saved_size); | |
690 | return r; | |
691 | } | |
692 | ||
693 | /* Append the OPT pseudo-RR described in RFC6891 */ | |
694 | int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start) { | |
695 | size_t saved_size; | |
696 | int r; | |
697 | ||
698 | assert(p); | |
699 | /* we must never advertise supported packet size smaller than the legacy max */ | |
700 | assert(max_udp_size >= DNS_PACKET_UNICAST_SIZE_MAX); | |
701 | assert(rcode >= 0); | |
702 | assert(rcode <= _DNS_RCODE_MAX); | |
703 | ||
704 | if (p->opt_start != (size_t) -1) | |
705 | return -EBUSY; | |
706 | ||
707 | assert(p->opt_size == (size_t) -1); | |
708 | ||
709 | saved_size = p->size; | |
710 | ||
711 | /* empty name */ | |
712 | r = dns_packet_append_uint8(p, 0, NULL); | |
713 | if (r < 0) | |
714 | return r; | |
715 | ||
716 | /* type */ | |
717 | r = dns_packet_append_uint16(p, DNS_TYPE_OPT, NULL); | |
718 | if (r < 0) | |
719 | goto fail; | |
720 | ||
721 | /* class: maximum udp packet that can be received */ | |
722 | r = dns_packet_append_uint16(p, max_udp_size, NULL); | |
723 | if (r < 0) | |
724 | goto fail; | |
725 | ||
726 | /* extended RCODE and VERSION */ | |
727 | r = dns_packet_append_uint16(p, ((uint16_t) rcode & 0x0FF0) << 4, NULL); | |
728 | if (r < 0) | |
729 | goto fail; | |
730 | ||
731 | /* flags: DNSSEC OK (DO), see RFC3225 */ | |
732 | r = dns_packet_append_uint16(p, edns0_do ? EDNS0_OPT_DO : 0, NULL); | |
733 | if (r < 0) | |
734 | goto fail; | |
735 | ||
736 | /* RDLENGTH */ | |
737 | if (edns0_do && !DNS_PACKET_QR(p)) { | |
738 | /* If DO is on and this is not a reply, also append RFC6975 Algorithm data */ | |
739 | ||
740 | static const uint8_t rfc6975[] = { | |
741 | ||
742 | 0, 5, /* OPTION_CODE: DAU */ | |
743 | #if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600 | |
744 | 0, 7, /* LIST_LENGTH */ | |
745 | #else | |
746 | 0, 6, /* LIST_LENGTH */ | |
747 | #endif | |
748 | DNSSEC_ALGORITHM_RSASHA1, | |
749 | DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1, | |
750 | DNSSEC_ALGORITHM_RSASHA256, | |
751 | DNSSEC_ALGORITHM_RSASHA512, | |
752 | DNSSEC_ALGORITHM_ECDSAP256SHA256, | |
753 | DNSSEC_ALGORITHM_ECDSAP384SHA384, | |
754 | #if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600 | |
755 | DNSSEC_ALGORITHM_ED25519, | |
756 | #endif | |
757 | ||
758 | 0, 6, /* OPTION_CODE: DHU */ | |
759 | 0, 3, /* LIST_LENGTH */ | |
760 | DNSSEC_DIGEST_SHA1, | |
761 | DNSSEC_DIGEST_SHA256, | |
762 | DNSSEC_DIGEST_SHA384, | |
763 | ||
764 | 0, 7, /* OPTION_CODE: N3U */ | |
765 | 0, 1, /* LIST_LENGTH */ | |
766 | NSEC3_ALGORITHM_SHA1, | |
767 | }; | |
768 | ||
769 | r = dns_packet_append_uint16(p, sizeof(rfc6975), NULL); | |
770 | if (r < 0) | |
771 | goto fail; | |
772 | ||
773 | r = dns_packet_append_blob(p, rfc6975, sizeof(rfc6975), NULL); | |
774 | } else | |
775 | r = dns_packet_append_uint16(p, 0, NULL); | |
776 | if (r < 0) | |
777 | goto fail; | |
778 | ||
779 | DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) + 1); | |
780 | ||
781 | p->opt_start = saved_size; | |
782 | p->opt_size = p->size - saved_size; | |
783 | ||
784 | if (start) | |
785 | *start = saved_size; | |
786 | ||
787 | return 0; | |
788 | ||
789 | fail: | |
790 | dns_packet_truncate(p, saved_size); | |
791 | return r; | |
792 | } | |
793 | ||
794 | int dns_packet_truncate_opt(DnsPacket *p) { | |
795 | assert(p); | |
796 | ||
797 | if (p->opt_start == (size_t) -1) { | |
798 | assert(p->opt_size == (size_t) -1); | |
799 | return 0; | |
800 | } | |
801 | ||
802 | assert(p->opt_size != (size_t) -1); | |
803 | assert(DNS_PACKET_ARCOUNT(p) > 0); | |
804 | ||
805 | if (p->opt_start + p->opt_size != p->size) | |
806 | return -EBUSY; | |
807 | ||
808 | dns_packet_truncate(p, p->opt_start); | |
809 | DNS_PACKET_HEADER(p)->arcount = htobe16(DNS_PACKET_ARCOUNT(p) - 1); | |
810 | p->opt_start = p->opt_size = (size_t) -1; | |
811 | ||
812 | return 1; | |
813 | } | |
814 | ||
815 | int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start) { | |
816 | ||
817 | size_t saved_size, rdlength_offset, end, rdlength, rds; | |
818 | uint32_t ttl; | |
819 | int r; | |
820 | ||
821 | assert(p); | |
822 | assert(rr); | |
823 | ||
824 | saved_size = p->size; | |
825 | ||
826 | r = dns_packet_append_key(p, rr->key, flags, NULL); | |
827 | if (r < 0) | |
828 | goto fail; | |
829 | ||
830 | ttl = flags & DNS_ANSWER_GOODBYE ? 0 : rr->ttl; | |
831 | r = dns_packet_append_uint32(p, ttl, NULL); | |
832 | if (r < 0) | |
833 | goto fail; | |
834 | ||
835 | /* Initially we write 0 here */ | |
836 | r = dns_packet_append_uint16(p, 0, &rdlength_offset); | |
837 | if (r < 0) | |
838 | goto fail; | |
839 | ||
840 | rds = p->size - saved_size; | |
841 | ||
842 | switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) { | |
843 | ||
844 | case DNS_TYPE_SRV: | |
845 | r = dns_packet_append_uint16(p, rr->srv.priority, NULL); | |
846 | if (r < 0) | |
847 | goto fail; | |
848 | ||
849 | r = dns_packet_append_uint16(p, rr->srv.weight, NULL); | |
850 | if (r < 0) | |
851 | goto fail; | |
852 | ||
853 | r = dns_packet_append_uint16(p, rr->srv.port, NULL); | |
854 | if (r < 0) | |
855 | goto fail; | |
856 | ||
857 | /* RFC 2782 states "Unless and until permitted by future standards | |
858 | * action, name compression is not to be used for this field." */ | |
859 | r = dns_packet_append_name(p, rr->srv.name, false, false, NULL); | |
860 | break; | |
861 | ||
862 | case DNS_TYPE_PTR: | |
863 | case DNS_TYPE_NS: | |
864 | case DNS_TYPE_CNAME: | |
865 | case DNS_TYPE_DNAME: | |
866 | r = dns_packet_append_name(p, rr->ptr.name, true, false, NULL); | |
867 | break; | |
868 | ||
869 | case DNS_TYPE_HINFO: | |
870 | r = dns_packet_append_string(p, rr->hinfo.cpu, NULL); | |
871 | if (r < 0) | |
872 | goto fail; | |
873 | ||
874 | r = dns_packet_append_string(p, rr->hinfo.os, NULL); | |
875 | break; | |
876 | ||
877 | case DNS_TYPE_SPF: /* exactly the same as TXT */ | |
878 | case DNS_TYPE_TXT: | |
879 | ||
880 | if (!rr->txt.items) { | |
881 | /* RFC 6763, section 6.1 suggests to generate | |
882 | * single empty string for an empty array. */ | |
883 | ||
884 | r = dns_packet_append_raw_string(p, NULL, 0, NULL); | |
885 | if (r < 0) | |
886 | goto fail; | |
887 | } else { | |
888 | DnsTxtItem *i; | |
889 | ||
890 | LIST_FOREACH(items, i, rr->txt.items) { | |
891 | r = dns_packet_append_raw_string(p, i->data, i->length, NULL); | |
892 | if (r < 0) | |
893 | goto fail; | |
894 | } | |
895 | } | |
896 | ||
897 | r = 0; | |
898 | break; | |
899 | ||
900 | case DNS_TYPE_A: | |
901 | r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL); | |
902 | break; | |
903 | ||
904 | case DNS_TYPE_AAAA: | |
905 | r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL); | |
906 | break; | |
907 | ||
908 | case DNS_TYPE_SOA: | |
909 | r = dns_packet_append_name(p, rr->soa.mname, true, false, NULL); | |
910 | if (r < 0) | |
911 | goto fail; | |
912 | ||
913 | r = dns_packet_append_name(p, rr->soa.rname, true, false, NULL); | |
914 | if (r < 0) | |
915 | goto fail; | |
916 | ||
917 | r = dns_packet_append_uint32(p, rr->soa.serial, NULL); | |
918 | if (r < 0) | |
919 | goto fail; | |
920 | ||
921 | r = dns_packet_append_uint32(p, rr->soa.refresh, NULL); | |
922 | if (r < 0) | |
923 | goto fail; | |
924 | ||
925 | r = dns_packet_append_uint32(p, rr->soa.retry, NULL); | |
926 | if (r < 0) | |
927 | goto fail; | |
928 | ||
929 | r = dns_packet_append_uint32(p, rr->soa.expire, NULL); | |
930 | if (r < 0) | |
931 | goto fail; | |
932 | ||
933 | r = dns_packet_append_uint32(p, rr->soa.minimum, NULL); | |
934 | break; | |
935 | ||
936 | case DNS_TYPE_MX: | |
937 | r = dns_packet_append_uint16(p, rr->mx.priority, NULL); | |
938 | if (r < 0) | |
939 | goto fail; | |
940 | ||
941 | r = dns_packet_append_name(p, rr->mx.exchange, true, false, NULL); | |
942 | break; | |
943 | ||
944 | case DNS_TYPE_LOC: | |
945 | r = dns_packet_append_uint8(p, rr->loc.version, NULL); | |
946 | if (r < 0) | |
947 | goto fail; | |
948 | ||
949 | r = dns_packet_append_uint8(p, rr->loc.size, NULL); | |
950 | if (r < 0) | |
951 | goto fail; | |
952 | ||
953 | r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL); | |
954 | if (r < 0) | |
955 | goto fail; | |
956 | ||
957 | r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL); | |
958 | if (r < 0) | |
959 | goto fail; | |
960 | ||
961 | r = dns_packet_append_uint32(p, rr->loc.latitude, NULL); | |
962 | if (r < 0) | |
963 | goto fail; | |
964 | ||
965 | r = dns_packet_append_uint32(p, rr->loc.longitude, NULL); | |
966 | if (r < 0) | |
967 | goto fail; | |
968 | ||
969 | r = dns_packet_append_uint32(p, rr->loc.altitude, NULL); | |
970 | break; | |
971 | ||
972 | case DNS_TYPE_DS: | |
973 | r = dns_packet_append_uint16(p, rr->ds.key_tag, NULL); | |
974 | if (r < 0) | |
975 | goto fail; | |
976 | ||
977 | r = dns_packet_append_uint8(p, rr->ds.algorithm, NULL); | |
978 | if (r < 0) | |
979 | goto fail; | |
980 | ||
981 | r = dns_packet_append_uint8(p, rr->ds.digest_type, NULL); | |
982 | if (r < 0) | |
983 | goto fail; | |
984 | ||
985 | r = dns_packet_append_blob(p, rr->ds.digest, rr->ds.digest_size, NULL); | |
986 | break; | |
987 | ||
988 | case DNS_TYPE_SSHFP: | |
989 | r = dns_packet_append_uint8(p, rr->sshfp.algorithm, NULL); | |
990 | if (r < 0) | |
991 | goto fail; | |
992 | ||
993 | r = dns_packet_append_uint8(p, rr->sshfp.fptype, NULL); | |
994 | if (r < 0) | |
995 | goto fail; | |
996 | ||
997 | r = dns_packet_append_blob(p, rr->sshfp.fingerprint, rr->sshfp.fingerprint_size, NULL); | |
998 | break; | |
999 | ||
1000 | case DNS_TYPE_DNSKEY: | |
1001 | r = dns_packet_append_uint16(p, rr->dnskey.flags, NULL); | |
1002 | if (r < 0) | |
1003 | goto fail; | |
1004 | ||
1005 | r = dns_packet_append_uint8(p, rr->dnskey.protocol, NULL); | |
1006 | if (r < 0) | |
1007 | goto fail; | |
1008 | ||
1009 | r = dns_packet_append_uint8(p, rr->dnskey.algorithm, NULL); | |
1010 | if (r < 0) | |
1011 | goto fail; | |
1012 | ||
1013 | r = dns_packet_append_blob(p, rr->dnskey.key, rr->dnskey.key_size, NULL); | |
1014 | break; | |
1015 | ||
1016 | case DNS_TYPE_RRSIG: | |
1017 | r = dns_packet_append_uint16(p, rr->rrsig.type_covered, NULL); | |
1018 | if (r < 0) | |
1019 | goto fail; | |
1020 | ||
1021 | r = dns_packet_append_uint8(p, rr->rrsig.algorithm, NULL); | |
1022 | if (r < 0) | |
1023 | goto fail; | |
1024 | ||
1025 | r = dns_packet_append_uint8(p, rr->rrsig.labels, NULL); | |
1026 | if (r < 0) | |
1027 | goto fail; | |
1028 | ||
1029 | r = dns_packet_append_uint32(p, rr->rrsig.original_ttl, NULL); | |
1030 | if (r < 0) | |
1031 | goto fail; | |
1032 | ||
1033 | r = dns_packet_append_uint32(p, rr->rrsig.expiration, NULL); | |
1034 | if (r < 0) | |
1035 | goto fail; | |
1036 | ||
1037 | r = dns_packet_append_uint32(p, rr->rrsig.inception, NULL); | |
1038 | if (r < 0) | |
1039 | goto fail; | |
1040 | ||
1041 | r = dns_packet_append_uint16(p, rr->rrsig.key_tag, NULL); | |
1042 | if (r < 0) | |
1043 | goto fail; | |
1044 | ||
1045 | r = dns_packet_append_name(p, rr->rrsig.signer, false, true, NULL); | |
1046 | if (r < 0) | |
1047 | goto fail; | |
1048 | ||
1049 | r = dns_packet_append_blob(p, rr->rrsig.signature, rr->rrsig.signature_size, NULL); | |
1050 | break; | |
1051 | ||
1052 | case DNS_TYPE_NSEC: | |
1053 | r = dns_packet_append_name(p, rr->nsec.next_domain_name, false, false, NULL); | |
1054 | if (r < 0) | |
1055 | goto fail; | |
1056 | ||
1057 | r = dns_packet_append_types(p, rr->nsec.types, NULL); | |
1058 | if (r < 0) | |
1059 | goto fail; | |
1060 | ||
1061 | break; | |
1062 | ||
1063 | case DNS_TYPE_NSEC3: | |
1064 | r = dns_packet_append_uint8(p, rr->nsec3.algorithm, NULL); | |
1065 | if (r < 0) | |
1066 | goto fail; | |
1067 | ||
1068 | r = dns_packet_append_uint8(p, rr->nsec3.flags, NULL); | |
1069 | if (r < 0) | |
1070 | goto fail; | |
1071 | ||
1072 | r = dns_packet_append_uint16(p, rr->nsec3.iterations, NULL); | |
1073 | if (r < 0) | |
1074 | goto fail; | |
1075 | ||
1076 | r = dns_packet_append_uint8(p, rr->nsec3.salt_size, NULL); | |
1077 | if (r < 0) | |
1078 | goto fail; | |
1079 | ||
1080 | r = dns_packet_append_blob(p, rr->nsec3.salt, rr->nsec3.salt_size, NULL); | |
1081 | if (r < 0) | |
1082 | goto fail; | |
1083 | ||
1084 | r = dns_packet_append_uint8(p, rr->nsec3.next_hashed_name_size, NULL); | |
1085 | if (r < 0) | |
1086 | goto fail; | |
1087 | ||
1088 | r = dns_packet_append_blob(p, rr->nsec3.next_hashed_name, rr->nsec3.next_hashed_name_size, NULL); | |
1089 | if (r < 0) | |
1090 | goto fail; | |
1091 | ||
1092 | r = dns_packet_append_types(p, rr->nsec3.types, NULL); | |
1093 | if (r < 0) | |
1094 | goto fail; | |
1095 | ||
1096 | break; | |
1097 | ||
1098 | case DNS_TYPE_TLSA: | |
1099 | r = dns_packet_append_uint8(p, rr->tlsa.cert_usage, NULL); | |
1100 | if (r < 0) | |
1101 | goto fail; | |
1102 | ||
1103 | r = dns_packet_append_uint8(p, rr->tlsa.selector, NULL); | |
1104 | if (r < 0) | |
1105 | goto fail; | |
1106 | ||
1107 | r = dns_packet_append_uint8(p, rr->tlsa.matching_type, NULL); | |
1108 | if (r < 0) | |
1109 | goto fail; | |
1110 | ||
1111 | r = dns_packet_append_blob(p, rr->tlsa.data, rr->tlsa.data_size, NULL); | |
1112 | break; | |
1113 | ||
1114 | case DNS_TYPE_CAA: | |
1115 | r = dns_packet_append_uint8(p, rr->caa.flags, NULL); | |
1116 | if (r < 0) | |
1117 | goto fail; | |
1118 | ||
1119 | r = dns_packet_append_string(p, rr->caa.tag, NULL); | |
1120 | if (r < 0) | |
1121 | goto fail; | |
1122 | ||
1123 | r = dns_packet_append_blob(p, rr->caa.value, rr->caa.value_size, NULL); | |
1124 | break; | |
1125 | ||
1126 | case DNS_TYPE_OPT: | |
1127 | case DNS_TYPE_OPENPGPKEY: | |
1128 | case _DNS_TYPE_INVALID: /* unparseable */ | |
1129 | default: | |
1130 | ||
1131 | r = dns_packet_append_blob(p, rr->generic.data, rr->generic.data_size, NULL); | |
1132 | break; | |
1133 | } | |
1134 | if (r < 0) | |
1135 | goto fail; | |
1136 | ||
1137 | /* Let's calculate the actual data size and update the field */ | |
1138 | rdlength = p->size - rdlength_offset - sizeof(uint16_t); | |
1139 | if (rdlength > 0xFFFF) { | |
1140 | r = -ENOSPC; | |
1141 | goto fail; | |
1142 | } | |
1143 | ||
1144 | end = p->size; | |
1145 | p->size = rdlength_offset; | |
1146 | r = dns_packet_append_uint16(p, rdlength, NULL); | |
1147 | if (r < 0) | |
1148 | goto fail; | |
1149 | p->size = end; | |
1150 | ||
1151 | if (start) | |
1152 | *start = saved_size; | |
1153 | ||
1154 | if (rdata_start) | |
1155 | *rdata_start = rds; | |
1156 | ||
1157 | return 0; | |
1158 | ||
1159 | fail: | |
1160 | dns_packet_truncate(p, saved_size); | |
1161 | return r; | |
1162 | } | |
1163 | ||
1164 | int dns_packet_append_question(DnsPacket *p, DnsQuestion *q) { | |
1165 | DnsResourceKey *key; | |
1166 | int r; | |
1167 | ||
1168 | assert(p); | |
1169 | ||
1170 | DNS_QUESTION_FOREACH(key, q) { | |
1171 | r = dns_packet_append_key(p, key, 0, NULL); | |
1172 | if (r < 0) | |
1173 | return r; | |
1174 | } | |
1175 | ||
1176 | return 0; | |
1177 | } | |
1178 | ||
1179 | int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a) { | |
1180 | DnsResourceRecord *rr; | |
1181 | DnsAnswerFlags flags; | |
1182 | int r; | |
1183 | ||
1184 | assert(p); | |
1185 | ||
1186 | DNS_ANSWER_FOREACH_FLAGS(rr, flags, a) { | |
1187 | r = dns_packet_append_rr(p, rr, flags, NULL, NULL); | |
1188 | if (r < 0) | |
1189 | return r; | |
1190 | } | |
1191 | ||
1192 | return 0; | |
1193 | } | |
1194 | ||
1195 | int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) { | |
1196 | assert(p); | |
1197 | ||
1198 | if (p->rindex + sz > p->size) | |
1199 | return -EMSGSIZE; | |
1200 | ||
1201 | if (ret) | |
1202 | *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex; | |
1203 | ||
1204 | if (start) | |
1205 | *start = p->rindex; | |
1206 | ||
1207 | p->rindex += sz; | |
1208 | return 0; | |
1209 | } | |
1210 | ||
1211 | void dns_packet_rewind(DnsPacket *p, size_t idx) { | |
1212 | assert(p); | |
1213 | assert(idx <= p->size); | |
1214 | assert(idx >= DNS_PACKET_HEADER_SIZE); | |
1215 | ||
1216 | p->rindex = idx; | |
1217 | } | |
1218 | ||
1219 | int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) { | |
1220 | const void *q; | |
1221 | int r; | |
1222 | ||
1223 | assert(p); | |
1224 | assert(d); | |
1225 | ||
1226 | r = dns_packet_read(p, sz, &q, start); | |
1227 | if (r < 0) | |
1228 | return r; | |
1229 | ||
1230 | memcpy(d, q, sz); | |
1231 | return 0; | |
1232 | } | |
1233 | ||
1234 | static int dns_packet_read_memdup( | |
1235 | DnsPacket *p, size_t size, | |
1236 | void **ret, size_t *ret_size, | |
1237 | size_t *ret_start) { | |
1238 | ||
1239 | const void *src; | |
1240 | size_t start; | |
1241 | int r; | |
1242 | ||
1243 | assert(p); | |
1244 | assert(ret); | |
1245 | ||
1246 | r = dns_packet_read(p, size, &src, &start); | |
1247 | if (r < 0) | |
1248 | return r; | |
1249 | ||
1250 | if (size <= 0) | |
1251 | *ret = NULL; | |
1252 | else { | |
1253 | void *copy; | |
1254 | ||
1255 | copy = memdup(src, size); | |
1256 | if (!copy) | |
1257 | return -ENOMEM; | |
1258 | ||
1259 | *ret = copy; | |
1260 | } | |
1261 | ||
1262 | if (ret_size) | |
1263 | *ret_size = size; | |
1264 | if (ret_start) | |
1265 | *ret_start = start; | |
1266 | ||
1267 | return 0; | |
1268 | } | |
1269 | ||
1270 | int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) { | |
1271 | const void *d; | |
1272 | int r; | |
1273 | ||
1274 | assert(p); | |
1275 | ||
1276 | r = dns_packet_read(p, sizeof(uint8_t), &d, start); | |
1277 | if (r < 0) | |
1278 | return r; | |
1279 | ||
1280 | *ret = ((uint8_t*) d)[0]; | |
1281 | return 0; | |
1282 | } | |
1283 | ||
1284 | int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) { | |
1285 | const void *d; | |
1286 | int r; | |
1287 | ||
1288 | assert(p); | |
1289 | ||
1290 | r = dns_packet_read(p, sizeof(uint16_t), &d, start); | |
1291 | if (r < 0) | |
1292 | return r; | |
1293 | ||
1294 | *ret = unaligned_read_be16(d); | |
1295 | ||
1296 | return 0; | |
1297 | } | |
1298 | ||
1299 | int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) { | |
1300 | const void *d; | |
1301 | int r; | |
1302 | ||
1303 | assert(p); | |
1304 | ||
1305 | r = dns_packet_read(p, sizeof(uint32_t), &d, start); | |
1306 | if (r < 0) | |
1307 | return r; | |
1308 | ||
1309 | *ret = unaligned_read_be32(d); | |
1310 | ||
1311 | return 0; | |
1312 | } | |
1313 | ||
1314 | int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) { | |
1315 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1316 | const void *d; | |
1317 | char *t; | |
1318 | uint8_t c; | |
1319 | int r; | |
1320 | ||
1321 | assert(p); | |
1322 | INIT_REWINDER(rewinder, p); | |
1323 | ||
1324 | r = dns_packet_read_uint8(p, &c, NULL); | |
1325 | if (r < 0) | |
1326 | return r; | |
1327 | ||
1328 | r = dns_packet_read(p, c, &d, NULL); | |
1329 | if (r < 0) | |
1330 | return r; | |
1331 | ||
1332 | if (memchr(d, 0, c)) | |
1333 | return -EBADMSG; | |
1334 | ||
1335 | t = strndup(d, c); | |
1336 | if (!t) | |
1337 | return -ENOMEM; | |
1338 | ||
1339 | if (!utf8_is_valid(t)) { | |
1340 | free(t); | |
1341 | return -EBADMSG; | |
1342 | } | |
1343 | ||
1344 | *ret = t; | |
1345 | ||
1346 | if (start) | |
1347 | *start = rewinder.saved_rindex; | |
1348 | CANCEL_REWINDER(rewinder); | |
1349 | ||
1350 | return 0; | |
1351 | } | |
1352 | ||
1353 | int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start) { | |
1354 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1355 | uint8_t c; | |
1356 | int r; | |
1357 | ||
1358 | assert(p); | |
1359 | INIT_REWINDER(rewinder, p); | |
1360 | ||
1361 | r = dns_packet_read_uint8(p, &c, NULL); | |
1362 | if (r < 0) | |
1363 | return r; | |
1364 | ||
1365 | r = dns_packet_read(p, c, ret, NULL); | |
1366 | if (r < 0) | |
1367 | return r; | |
1368 | ||
1369 | if (size) | |
1370 | *size = c; | |
1371 | if (start) | |
1372 | *start = rewinder.saved_rindex; | |
1373 | CANCEL_REWINDER(rewinder); | |
1374 | ||
1375 | return 0; | |
1376 | } | |
1377 | ||
1378 | int dns_packet_read_name( | |
1379 | DnsPacket *p, | |
1380 | char **_ret, | |
1381 | bool allow_compression, | |
1382 | size_t *start) { | |
1383 | ||
1384 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1385 | size_t after_rindex = 0, jump_barrier; | |
1386 | _cleanup_free_ char *ret = NULL; | |
1387 | size_t n = 0, allocated = 0; | |
1388 | bool first = true; | |
1389 | int r; | |
1390 | ||
1391 | assert(p); | |
1392 | assert(_ret); | |
1393 | INIT_REWINDER(rewinder, p); | |
1394 | jump_barrier = p->rindex; | |
1395 | ||
1396 | if (p->refuse_compression) | |
1397 | allow_compression = false; | |
1398 | ||
1399 | for (;;) { | |
1400 | uint8_t c, d; | |
1401 | ||
1402 | r = dns_packet_read_uint8(p, &c, NULL); | |
1403 | if (r < 0) | |
1404 | return r; | |
1405 | ||
1406 | if (c == 0) | |
1407 | /* End of name */ | |
1408 | break; | |
1409 | else if (c <= 63) { | |
1410 | const char *label; | |
1411 | ||
1412 | /* Literal label */ | |
1413 | r = dns_packet_read(p, c, (const void**) &label, NULL); | |
1414 | if (r < 0) | |
1415 | return r; | |
1416 | ||
1417 | if (!GREEDY_REALLOC(ret, allocated, n + !first + DNS_LABEL_ESCAPED_MAX)) | |
1418 | return -ENOMEM; | |
1419 | ||
1420 | if (first) | |
1421 | first = false; | |
1422 | else | |
1423 | ret[n++] = '.'; | |
1424 | ||
1425 | r = dns_label_escape(label, c, ret + n, DNS_LABEL_ESCAPED_MAX); | |
1426 | if (r < 0) | |
1427 | return r; | |
1428 | ||
1429 | n += r; | |
1430 | continue; | |
1431 | } else if (allow_compression && (c & 0xc0) == 0xc0) { | |
1432 | uint16_t ptr; | |
1433 | ||
1434 | /* Pointer */ | |
1435 | r = dns_packet_read_uint8(p, &d, NULL); | |
1436 | if (r < 0) | |
1437 | return r; | |
1438 | ||
1439 | ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d; | |
1440 | if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= jump_barrier) | |
1441 | return -EBADMSG; | |
1442 | ||
1443 | if (after_rindex == 0) | |
1444 | after_rindex = p->rindex; | |
1445 | ||
1446 | /* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */ | |
1447 | jump_barrier = ptr; | |
1448 | p->rindex = ptr; | |
1449 | } else | |
1450 | return -EBADMSG; | |
1451 | } | |
1452 | ||
1453 | if (!GREEDY_REALLOC(ret, allocated, n + 1)) | |
1454 | return -ENOMEM; | |
1455 | ||
1456 | ret[n] = 0; | |
1457 | ||
1458 | if (after_rindex != 0) | |
1459 | p->rindex= after_rindex; | |
1460 | ||
1461 | *_ret = TAKE_PTR(ret); | |
1462 | ||
1463 | if (start) | |
1464 | *start = rewinder.saved_rindex; | |
1465 | CANCEL_REWINDER(rewinder); | |
1466 | ||
1467 | return 0; | |
1468 | } | |
1469 | ||
1470 | static int dns_packet_read_type_window(DnsPacket *p, Bitmap **types, size_t *start) { | |
1471 | uint8_t window; | |
1472 | uint8_t length; | |
1473 | const uint8_t *bitmap; | |
1474 | uint8_t bit = 0; | |
1475 | unsigned i; | |
1476 | bool found = false; | |
1477 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1478 | int r; | |
1479 | ||
1480 | assert(p); | |
1481 | assert(types); | |
1482 | INIT_REWINDER(rewinder, p); | |
1483 | ||
1484 | r = bitmap_ensure_allocated(types); | |
1485 | if (r < 0) | |
1486 | return r; | |
1487 | ||
1488 | r = dns_packet_read_uint8(p, &window, NULL); | |
1489 | if (r < 0) | |
1490 | return r; | |
1491 | ||
1492 | r = dns_packet_read_uint8(p, &length, NULL); | |
1493 | if (r < 0) | |
1494 | return r; | |
1495 | ||
1496 | if (length == 0 || length > 32) | |
1497 | return -EBADMSG; | |
1498 | ||
1499 | r = dns_packet_read(p, length, (const void **)&bitmap, NULL); | |
1500 | if (r < 0) | |
1501 | return r; | |
1502 | ||
1503 | for (i = 0; i < length; i++) { | |
1504 | uint8_t bitmask = 1 << 7; | |
1505 | ||
1506 | if (!bitmap[i]) { | |
1507 | found = false; | |
1508 | bit += 8; | |
1509 | continue; | |
1510 | } | |
1511 | ||
1512 | found = true; | |
1513 | ||
1514 | for (; bitmask; bit++, bitmask >>= 1) | |
1515 | if (bitmap[i] & bitmask) { | |
1516 | uint16_t n; | |
1517 | ||
1518 | n = (uint16_t) window << 8 | (uint16_t) bit; | |
1519 | ||
1520 | /* Ignore pseudo-types. see RFC4034 section 4.1.2 */ | |
1521 | if (dns_type_is_pseudo(n)) | |
1522 | continue; | |
1523 | ||
1524 | r = bitmap_set(*types, n); | |
1525 | if (r < 0) | |
1526 | return r; | |
1527 | } | |
1528 | } | |
1529 | ||
1530 | if (!found) | |
1531 | return -EBADMSG; | |
1532 | ||
1533 | if (start) | |
1534 | *start = rewinder.saved_rindex; | |
1535 | CANCEL_REWINDER(rewinder); | |
1536 | ||
1537 | return 0; | |
1538 | } | |
1539 | ||
1540 | static int dns_packet_read_type_windows(DnsPacket *p, Bitmap **types, size_t size, size_t *start) { | |
1541 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1542 | int r; | |
1543 | ||
1544 | INIT_REWINDER(rewinder, p); | |
1545 | ||
1546 | while (p->rindex < rewinder.saved_rindex + size) { | |
1547 | r = dns_packet_read_type_window(p, types, NULL); | |
1548 | if (r < 0) | |
1549 | return r; | |
1550 | ||
1551 | /* don't read past end of current RR */ | |
1552 | if (p->rindex > rewinder.saved_rindex + size) | |
1553 | return -EBADMSG; | |
1554 | } | |
1555 | ||
1556 | if (p->rindex != rewinder.saved_rindex + size) | |
1557 | return -EBADMSG; | |
1558 | ||
1559 | if (start) | |
1560 | *start = rewinder.saved_rindex; | |
1561 | CANCEL_REWINDER(rewinder); | |
1562 | ||
1563 | return 0; | |
1564 | } | |
1565 | ||
1566 | int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start) { | |
1567 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1568 | _cleanup_free_ char *name = NULL; | |
1569 | bool cache_flush = false; | |
1570 | uint16_t class, type; | |
1571 | DnsResourceKey *key; | |
1572 | int r; | |
1573 | ||
1574 | assert(p); | |
1575 | assert(ret); | |
1576 | INIT_REWINDER(rewinder, p); | |
1577 | ||
1578 | r = dns_packet_read_name(p, &name, true, NULL); | |
1579 | if (r < 0) | |
1580 | return r; | |
1581 | ||
1582 | r = dns_packet_read_uint16(p, &type, NULL); | |
1583 | if (r < 0) | |
1584 | return r; | |
1585 | ||
1586 | r = dns_packet_read_uint16(p, &class, NULL); | |
1587 | if (r < 0) | |
1588 | return r; | |
1589 | ||
1590 | if (p->protocol == DNS_PROTOCOL_MDNS) { | |
1591 | /* See RFC6762, Section 10.2 */ | |
1592 | ||
1593 | if (type != DNS_TYPE_OPT && (class & MDNS_RR_CACHE_FLUSH)) { | |
1594 | class &= ~MDNS_RR_CACHE_FLUSH; | |
1595 | cache_flush = true; | |
1596 | } | |
1597 | } | |
1598 | ||
1599 | key = dns_resource_key_new_consume(class, type, name); | |
1600 | if (!key) | |
1601 | return -ENOMEM; | |
1602 | ||
1603 | name = NULL; | |
1604 | *ret = key; | |
1605 | ||
1606 | if (ret_cache_flush) | |
1607 | *ret_cache_flush = cache_flush; | |
1608 | if (start) | |
1609 | *start = rewinder.saved_rindex; | |
1610 | CANCEL_REWINDER(rewinder); | |
1611 | ||
1612 | return 0; | |
1613 | } | |
1614 | ||
1615 | static bool loc_size_ok(uint8_t size) { | |
1616 | uint8_t m = size >> 4, e = size & 0xF; | |
1617 | ||
1618 | return m <= 9 && e <= 9 && (m > 0 || e == 0); | |
1619 | } | |
1620 | ||
1621 | int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, size_t *start) { | |
1622 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
1623 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; | |
1624 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder; | |
1625 | size_t offset; | |
1626 | uint16_t rdlength; | |
1627 | bool cache_flush; | |
1628 | int r; | |
1629 | ||
1630 | assert(p); | |
1631 | assert(ret); | |
1632 | ||
1633 | INIT_REWINDER(rewinder, p); | |
1634 | ||
1635 | r = dns_packet_read_key(p, &key, &cache_flush, NULL); | |
1636 | if (r < 0) | |
1637 | return r; | |
1638 | ||
1639 | if (!dns_class_is_valid_rr(key->class) || !dns_type_is_valid_rr(key->type)) | |
1640 | return -EBADMSG; | |
1641 | ||
1642 | rr = dns_resource_record_new(key); | |
1643 | if (!rr) | |
1644 | return -ENOMEM; | |
1645 | ||
1646 | r = dns_packet_read_uint32(p, &rr->ttl, NULL); | |
1647 | if (r < 0) | |
1648 | return r; | |
1649 | ||
1650 | /* RFC 2181, Section 8, suggests to | |
1651 | * treat a TTL with the MSB set as a zero TTL. */ | |
1652 | if (rr->ttl & UINT32_C(0x80000000)) | |
1653 | rr->ttl = 0; | |
1654 | ||
1655 | r = dns_packet_read_uint16(p, &rdlength, NULL); | |
1656 | if (r < 0) | |
1657 | return r; | |
1658 | ||
1659 | if (p->rindex + rdlength > p->size) | |
1660 | return -EBADMSG; | |
1661 | ||
1662 | offset = p->rindex; | |
1663 | ||
1664 | switch (rr->key->type) { | |
1665 | ||
1666 | case DNS_TYPE_SRV: | |
1667 | r = dns_packet_read_uint16(p, &rr->srv.priority, NULL); | |
1668 | if (r < 0) | |
1669 | return r; | |
1670 | r = dns_packet_read_uint16(p, &rr->srv.weight, NULL); | |
1671 | if (r < 0) | |
1672 | return r; | |
1673 | r = dns_packet_read_uint16(p, &rr->srv.port, NULL); | |
1674 | if (r < 0) | |
1675 | return r; | |
1676 | r = dns_packet_read_name(p, &rr->srv.name, true, NULL); | |
1677 | break; | |
1678 | ||
1679 | case DNS_TYPE_PTR: | |
1680 | case DNS_TYPE_NS: | |
1681 | case DNS_TYPE_CNAME: | |
1682 | case DNS_TYPE_DNAME: | |
1683 | r = dns_packet_read_name(p, &rr->ptr.name, true, NULL); | |
1684 | break; | |
1685 | ||
1686 | case DNS_TYPE_HINFO: | |
1687 | r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL); | |
1688 | if (r < 0) | |
1689 | return r; | |
1690 | ||
1691 | r = dns_packet_read_string(p, &rr->hinfo.os, NULL); | |
1692 | break; | |
1693 | ||
1694 | case DNS_TYPE_SPF: /* exactly the same as TXT */ | |
1695 | case DNS_TYPE_TXT: | |
1696 | if (rdlength <= 0) { | |
1697 | r = dns_txt_item_new_empty(&rr->txt.items); | |
1698 | if (r < 0) | |
1699 | return r; | |
1700 | } else { | |
1701 | DnsTxtItem *last = NULL; | |
1702 | ||
1703 | while (p->rindex < offset + rdlength) { | |
1704 | DnsTxtItem *i; | |
1705 | const void *data; | |
1706 | size_t sz; | |
1707 | ||
1708 | r = dns_packet_read_raw_string(p, &data, &sz, NULL); | |
1709 | if (r < 0) | |
1710 | return r; | |
1711 | ||
1712 | i = malloc0(offsetof(DnsTxtItem, data) + sz + 1); /* extra NUL byte at the end */ | |
1713 | if (!i) | |
1714 | return -ENOMEM; | |
1715 | ||
1716 | memcpy(i->data, data, sz); | |
1717 | i->length = sz; | |
1718 | ||
1719 | LIST_INSERT_AFTER(items, rr->txt.items, last, i); | |
1720 | last = i; | |
1721 | } | |
1722 | } | |
1723 | ||
1724 | r = 0; | |
1725 | break; | |
1726 | ||
1727 | case DNS_TYPE_A: | |
1728 | r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL); | |
1729 | break; | |
1730 | ||
1731 | case DNS_TYPE_AAAA: | |
1732 | r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL); | |
1733 | break; | |
1734 | ||
1735 | case DNS_TYPE_SOA: | |
1736 | r = dns_packet_read_name(p, &rr->soa.mname, true, NULL); | |
1737 | if (r < 0) | |
1738 | return r; | |
1739 | ||
1740 | r = dns_packet_read_name(p, &rr->soa.rname, true, NULL); | |
1741 | if (r < 0) | |
1742 | return r; | |
1743 | ||
1744 | r = dns_packet_read_uint32(p, &rr->soa.serial, NULL); | |
1745 | if (r < 0) | |
1746 | return r; | |
1747 | ||
1748 | r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL); | |
1749 | if (r < 0) | |
1750 | return r; | |
1751 | ||
1752 | r = dns_packet_read_uint32(p, &rr->soa.retry, NULL); | |
1753 | if (r < 0) | |
1754 | return r; | |
1755 | ||
1756 | r = dns_packet_read_uint32(p, &rr->soa.expire, NULL); | |
1757 | if (r < 0) | |
1758 | return r; | |
1759 | ||
1760 | r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL); | |
1761 | break; | |
1762 | ||
1763 | case DNS_TYPE_MX: | |
1764 | r = dns_packet_read_uint16(p, &rr->mx.priority, NULL); | |
1765 | if (r < 0) | |
1766 | return r; | |
1767 | ||
1768 | r = dns_packet_read_name(p, &rr->mx.exchange, true, NULL); | |
1769 | break; | |
1770 | ||
1771 | case DNS_TYPE_LOC: { | |
1772 | uint8_t t; | |
1773 | size_t pos; | |
1774 | ||
1775 | r = dns_packet_read_uint8(p, &t, &pos); | |
1776 | if (r < 0) | |
1777 | return r; | |
1778 | ||
1779 | if (t == 0) { | |
1780 | rr->loc.version = t; | |
1781 | ||
1782 | r = dns_packet_read_uint8(p, &rr->loc.size, NULL); | |
1783 | if (r < 0) | |
1784 | return r; | |
1785 | ||
1786 | if (!loc_size_ok(rr->loc.size)) | |
1787 | return -EBADMSG; | |
1788 | ||
1789 | r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL); | |
1790 | if (r < 0) | |
1791 | return r; | |
1792 | ||
1793 | if (!loc_size_ok(rr->loc.horiz_pre)) | |
1794 | return -EBADMSG; | |
1795 | ||
1796 | r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL); | |
1797 | if (r < 0) | |
1798 | return r; | |
1799 | ||
1800 | if (!loc_size_ok(rr->loc.vert_pre)) | |
1801 | return -EBADMSG; | |
1802 | ||
1803 | r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL); | |
1804 | if (r < 0) | |
1805 | return r; | |
1806 | ||
1807 | r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL); | |
1808 | if (r < 0) | |
1809 | return r; | |
1810 | ||
1811 | r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL); | |
1812 | if (r < 0) | |
1813 | return r; | |
1814 | ||
1815 | break; | |
1816 | } else { | |
1817 | dns_packet_rewind(p, pos); | |
1818 | rr->unparseable = true; | |
1819 | goto unparseable; | |
1820 | } | |
1821 | } | |
1822 | ||
1823 | case DNS_TYPE_DS: | |
1824 | r = dns_packet_read_uint16(p, &rr->ds.key_tag, NULL); | |
1825 | if (r < 0) | |
1826 | return r; | |
1827 | ||
1828 | r = dns_packet_read_uint8(p, &rr->ds.algorithm, NULL); | |
1829 | if (r < 0) | |
1830 | return r; | |
1831 | ||
1832 | r = dns_packet_read_uint8(p, &rr->ds.digest_type, NULL); | |
1833 | if (r < 0) | |
1834 | return r; | |
1835 | ||
1836 | if (rdlength < 4) | |
1837 | return -EBADMSG; | |
1838 | ||
1839 | r = dns_packet_read_memdup(p, rdlength - 4, | |
1840 | &rr->ds.digest, &rr->ds.digest_size, | |
1841 | NULL); | |
1842 | if (r < 0) | |
1843 | return r; | |
1844 | ||
1845 | if (rr->ds.digest_size <= 0) | |
1846 | /* the accepted size depends on the algorithm, but for now | |
1847 | just ensure that the value is greater than zero */ | |
1848 | return -EBADMSG; | |
1849 | ||
1850 | break; | |
1851 | ||
1852 | case DNS_TYPE_SSHFP: | |
1853 | r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL); | |
1854 | if (r < 0) | |
1855 | return r; | |
1856 | ||
1857 | r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL); | |
1858 | if (r < 0) | |
1859 | return r; | |
1860 | ||
1861 | if (rdlength < 2) | |
1862 | return -EBADMSG; | |
1863 | ||
1864 | r = dns_packet_read_memdup(p, rdlength - 2, | |
1865 | &rr->sshfp.fingerprint, &rr->sshfp.fingerprint_size, | |
1866 | NULL); | |
1867 | ||
1868 | if (rr->sshfp.fingerprint_size <= 0) | |
1869 | /* the accepted size depends on the algorithm, but for now | |
1870 | just ensure that the value is greater than zero */ | |
1871 | return -EBADMSG; | |
1872 | ||
1873 | break; | |
1874 | ||
1875 | case DNS_TYPE_DNSKEY: | |
1876 | r = dns_packet_read_uint16(p, &rr->dnskey.flags, NULL); | |
1877 | if (r < 0) | |
1878 | return r; | |
1879 | ||
1880 | r = dns_packet_read_uint8(p, &rr->dnskey.protocol, NULL); | |
1881 | if (r < 0) | |
1882 | return r; | |
1883 | ||
1884 | r = dns_packet_read_uint8(p, &rr->dnskey.algorithm, NULL); | |
1885 | if (r < 0) | |
1886 | return r; | |
1887 | ||
1888 | if (rdlength < 4) | |
1889 | return -EBADMSG; | |
1890 | ||
1891 | r = dns_packet_read_memdup(p, rdlength - 4, | |
1892 | &rr->dnskey.key, &rr->dnskey.key_size, | |
1893 | NULL); | |
1894 | ||
1895 | if (rr->dnskey.key_size <= 0) | |
1896 | /* the accepted size depends on the algorithm, but for now | |
1897 | just ensure that the value is greater than zero */ | |
1898 | return -EBADMSG; | |
1899 | ||
1900 | break; | |
1901 | ||
1902 | case DNS_TYPE_RRSIG: | |
1903 | r = dns_packet_read_uint16(p, &rr->rrsig.type_covered, NULL); | |
1904 | if (r < 0) | |
1905 | return r; | |
1906 | ||
1907 | r = dns_packet_read_uint8(p, &rr->rrsig.algorithm, NULL); | |
1908 | if (r < 0) | |
1909 | return r; | |
1910 | ||
1911 | r = dns_packet_read_uint8(p, &rr->rrsig.labels, NULL); | |
1912 | if (r < 0) | |
1913 | return r; | |
1914 | ||
1915 | r = dns_packet_read_uint32(p, &rr->rrsig.original_ttl, NULL); | |
1916 | if (r < 0) | |
1917 | return r; | |
1918 | ||
1919 | r = dns_packet_read_uint32(p, &rr->rrsig.expiration, NULL); | |
1920 | if (r < 0) | |
1921 | return r; | |
1922 | ||
1923 | r = dns_packet_read_uint32(p, &rr->rrsig.inception, NULL); | |
1924 | if (r < 0) | |
1925 | return r; | |
1926 | ||
1927 | r = dns_packet_read_uint16(p, &rr->rrsig.key_tag, NULL); | |
1928 | if (r < 0) | |
1929 | return r; | |
1930 | ||
1931 | r = dns_packet_read_name(p, &rr->rrsig.signer, false, NULL); | |
1932 | if (r < 0) | |
1933 | return r; | |
1934 | ||
1935 | if (rdlength + offset < p->rindex) | |
1936 | return -EBADMSG; | |
1937 | ||
1938 | r = dns_packet_read_memdup(p, offset + rdlength - p->rindex, | |
1939 | &rr->rrsig.signature, &rr->rrsig.signature_size, | |
1940 | NULL); | |
1941 | ||
1942 | if (rr->rrsig.signature_size <= 0) | |
1943 | /* the accepted size depends on the algorithm, but for now | |
1944 | just ensure that the value is greater than zero */ | |
1945 | return -EBADMSG; | |
1946 | ||
1947 | break; | |
1948 | ||
1949 | case DNS_TYPE_NSEC: { | |
1950 | ||
1951 | /* | |
1952 | * RFC6762, section 18.14 explictly states mDNS should use name compression. | |
1953 | * This contradicts RFC3845, section 2.1.1 | |
1954 | */ | |
1955 | ||
1956 | bool allow_compressed = p->protocol == DNS_PROTOCOL_MDNS; | |
1957 | ||
1958 | r = dns_packet_read_name(p, &rr->nsec.next_domain_name, allow_compressed, NULL); | |
1959 | if (r < 0) | |
1960 | return r; | |
1961 | ||
1962 | r = dns_packet_read_type_windows(p, &rr->nsec.types, offset + rdlength - p->rindex, NULL); | |
1963 | ||
1964 | /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself | |
1965 | * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records | |
1966 | * without the NSEC bit set. */ | |
1967 | ||
1968 | break; | |
1969 | } | |
1970 | case DNS_TYPE_NSEC3: { | |
1971 | uint8_t size; | |
1972 | ||
1973 | r = dns_packet_read_uint8(p, &rr->nsec3.algorithm, NULL); | |
1974 | if (r < 0) | |
1975 | return r; | |
1976 | ||
1977 | r = dns_packet_read_uint8(p, &rr->nsec3.flags, NULL); | |
1978 | if (r < 0) | |
1979 | return r; | |
1980 | ||
1981 | r = dns_packet_read_uint16(p, &rr->nsec3.iterations, NULL); | |
1982 | if (r < 0) | |
1983 | return r; | |
1984 | ||
1985 | /* this may be zero */ | |
1986 | r = dns_packet_read_uint8(p, &size, NULL); | |
1987 | if (r < 0) | |
1988 | return r; | |
1989 | ||
1990 | r = dns_packet_read_memdup(p, size, &rr->nsec3.salt, &rr->nsec3.salt_size, NULL); | |
1991 | if (r < 0) | |
1992 | return r; | |
1993 | ||
1994 | r = dns_packet_read_uint8(p, &size, NULL); | |
1995 | if (r < 0) | |
1996 | return r; | |
1997 | ||
1998 | if (size <= 0) | |
1999 | return -EBADMSG; | |
2000 | ||
2001 | r = dns_packet_read_memdup(p, size, | |
2002 | &rr->nsec3.next_hashed_name, &rr->nsec3.next_hashed_name_size, | |
2003 | NULL); | |
2004 | if (r < 0) | |
2005 | return r; | |
2006 | ||
2007 | r = dns_packet_read_type_windows(p, &rr->nsec3.types, offset + rdlength - p->rindex, NULL); | |
2008 | ||
2009 | /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */ | |
2010 | ||
2011 | break; | |
2012 | } | |
2013 | ||
2014 | case DNS_TYPE_TLSA: | |
2015 | r = dns_packet_read_uint8(p, &rr->tlsa.cert_usage, NULL); | |
2016 | if (r < 0) | |
2017 | return r; | |
2018 | ||
2019 | r = dns_packet_read_uint8(p, &rr->tlsa.selector, NULL); | |
2020 | if (r < 0) | |
2021 | return r; | |
2022 | ||
2023 | r = dns_packet_read_uint8(p, &rr->tlsa.matching_type, NULL); | |
2024 | if (r < 0) | |
2025 | return r; | |
2026 | ||
2027 | if (rdlength < 3) | |
2028 | return -EBADMSG; | |
2029 | ||
2030 | r = dns_packet_read_memdup(p, rdlength - 3, | |
2031 | &rr->tlsa.data, &rr->tlsa.data_size, | |
2032 | NULL); | |
2033 | ||
2034 | if (rr->tlsa.data_size <= 0) | |
2035 | /* the accepted size depends on the algorithm, but for now | |
2036 | just ensure that the value is greater than zero */ | |
2037 | return -EBADMSG; | |
2038 | ||
2039 | break; | |
2040 | ||
2041 | case DNS_TYPE_CAA: | |
2042 | r = dns_packet_read_uint8(p, &rr->caa.flags, NULL); | |
2043 | if (r < 0) | |
2044 | return r; | |
2045 | ||
2046 | r = dns_packet_read_string(p, &rr->caa.tag, NULL); | |
2047 | if (r < 0) | |
2048 | return r; | |
2049 | ||
2050 | if (rdlength + offset < p->rindex) | |
2051 | return -EBADMSG; | |
2052 | ||
2053 | r = dns_packet_read_memdup(p, | |
2054 | rdlength + offset - p->rindex, | |
2055 | &rr->caa.value, &rr->caa.value_size, NULL); | |
2056 | ||
2057 | break; | |
2058 | ||
2059 | case DNS_TYPE_OPT: /* we only care about the header of OPT for now. */ | |
2060 | case DNS_TYPE_OPENPGPKEY: | |
2061 | default: | |
2062 | unparseable: | |
2063 | r = dns_packet_read_memdup(p, rdlength, &rr->generic.data, &rr->generic.data_size, NULL); | |
2064 | ||
2065 | break; | |
2066 | } | |
2067 | if (r < 0) | |
2068 | return r; | |
2069 | if (p->rindex != offset + rdlength) | |
2070 | return -EBADMSG; | |
2071 | ||
2072 | *ret = TAKE_PTR(rr); | |
2073 | ||
2074 | if (ret_cache_flush) | |
2075 | *ret_cache_flush = cache_flush; | |
2076 | if (start) | |
2077 | *start = rewinder.saved_rindex; | |
2078 | CANCEL_REWINDER(rewinder); | |
2079 | ||
2080 | return 0; | |
2081 | } | |
2082 | ||
2083 | static bool opt_is_good(DnsResourceRecord *rr, bool *rfc6975) { | |
2084 | const uint8_t* p; | |
2085 | bool found_dau_dhu_n3u = false; | |
2086 | size_t l; | |
2087 | ||
2088 | /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in | |
2089 | * a reply). */ | |
2090 | ||
2091 | assert(rr); | |
2092 | assert(rr->key->type == DNS_TYPE_OPT); | |
2093 | ||
2094 | /* Check that the version is 0 */ | |
2095 | if (((rr->ttl >> 16) & UINT32_C(0xFF)) != 0) { | |
2096 | *rfc6975 = false; | |
2097 | return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */ | |
2098 | } | |
2099 | ||
2100 | p = rr->opt.data; | |
2101 | l = rr->opt.data_size; | |
2102 | while (l > 0) { | |
2103 | uint16_t option_code, option_length; | |
2104 | ||
2105 | /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */ | |
2106 | if (l < 4U) | |
2107 | return false; | |
2108 | ||
2109 | option_code = unaligned_read_be16(p); | |
2110 | option_length = unaligned_read_be16(p + 2); | |
2111 | ||
2112 | if (l < option_length + 4U) | |
2113 | return false; | |
2114 | ||
2115 | /* RFC 6975 DAU, DHU or N3U fields found. */ | |
2116 | if (IN_SET(option_code, 5, 6, 7)) | |
2117 | found_dau_dhu_n3u = true; | |
2118 | ||
2119 | p += option_length + 4U; | |
2120 | l -= option_length + 4U; | |
2121 | } | |
2122 | ||
2123 | *rfc6975 = found_dau_dhu_n3u; | |
2124 | return true; | |
2125 | } | |
2126 | ||
2127 | static int dns_packet_extract_question(DnsPacket *p, DnsQuestion **ret_question) { | |
2128 | _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; | |
2129 | unsigned n, i; | |
2130 | int r; | |
2131 | ||
2132 | n = DNS_PACKET_QDCOUNT(p); | |
2133 | if (n > 0) { | |
2134 | question = dns_question_new(n); | |
2135 | if (!question) | |
2136 | return -ENOMEM; | |
2137 | ||
2138 | _cleanup_set_free_ Set *keys = NULL; /* references to keys are kept by Question */ | |
2139 | ||
2140 | keys = set_new(&dns_resource_key_hash_ops); | |
2141 | if (!keys) | |
2142 | return log_oom(); | |
2143 | ||
2144 | r = set_reserve(keys, n * 2); /* Higher multipliers give slightly higher efficiency through | |
2145 | * hash collisions, but the gains quickly drop of after 2. */ | |
2146 | if (r < 0) | |
2147 | return r; | |
2148 | ||
2149 | for (i = 0; i < n; i++) { | |
2150 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; | |
2151 | bool cache_flush; | |
2152 | ||
2153 | r = dns_packet_read_key(p, &key, &cache_flush, NULL); | |
2154 | if (r < 0) | |
2155 | return r; | |
2156 | ||
2157 | if (cache_flush) | |
2158 | return -EBADMSG; | |
2159 | ||
2160 | if (!dns_type_is_valid_query(key->type)) | |
2161 | return -EBADMSG; | |
2162 | ||
2163 | r = set_put(keys, key); | |
2164 | if (r < 0) | |
2165 | return r; | |
2166 | if (r == 0) | |
2167 | /* Already in the Question, let's skip */ | |
2168 | continue; | |
2169 | ||
2170 | r = dns_question_add_raw(question, key); | |
2171 | if (r < 0) | |
2172 | return r; | |
2173 | } | |
2174 | } | |
2175 | ||
2176 | *ret_question = TAKE_PTR(question); | |
2177 | ||
2178 | return 0; | |
2179 | } | |
2180 | ||
2181 | static int dns_packet_extract_answer(DnsPacket *p, DnsAnswer **ret_answer) { | |
2182 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; | |
2183 | unsigned n, i; | |
2184 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *previous = NULL; | |
2185 | bool bad_opt = false; | |
2186 | int r; | |
2187 | ||
2188 | n = DNS_PACKET_RRCOUNT(p); | |
2189 | if (n == 0) | |
2190 | return 0; | |
2191 | ||
2192 | answer = dns_answer_new(n); | |
2193 | if (!answer) | |
2194 | return -ENOMEM; | |
2195 | ||
2196 | for (i = 0; i < n; i++) { | |
2197 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; | |
2198 | bool cache_flush = false; | |
2199 | ||
2200 | r = dns_packet_read_rr(p, &rr, &cache_flush, NULL); | |
2201 | if (r < 0) | |
2202 | return r; | |
2203 | ||
2204 | /* Try to reduce memory usage a bit */ | |
2205 | if (previous) | |
2206 | dns_resource_key_reduce(&rr->key, &previous->key); | |
2207 | ||
2208 | if (rr->key->type == DNS_TYPE_OPT) { | |
2209 | bool has_rfc6975; | |
2210 | ||
2211 | if (p->opt || bad_opt) { | |
2212 | /* Multiple OPT RRs? if so, let's ignore all, because there's | |
2213 | * something wrong with the server, and if one is valid we wouldn't | |
2214 | * know which one. */ | |
2215 | log_debug("Multiple OPT RRs detected, ignoring all."); | |
2216 | bad_opt = true; | |
2217 | continue; | |
2218 | } | |
2219 | ||
2220 | if (!dns_name_is_root(dns_resource_key_name(rr->key))) { | |
2221 | /* If the OPT RR is not owned by the root domain, then it is bad, | |
2222 | * let's ignore it. */ | |
2223 | log_debug("OPT RR is not owned by root domain, ignoring."); | |
2224 | bad_opt = true; | |
2225 | continue; | |
2226 | } | |
2227 | ||
2228 | if (i < DNS_PACKET_ANCOUNT(p) + DNS_PACKET_NSCOUNT(p)) { | |
2229 | /* OPT RR is in the wrong section? Some Belkin routers do this. This | |
2230 | * is a hint the EDNS implementation is borked, like the Belkin one | |
2231 | * is, hence ignore it. */ | |
2232 | log_debug("OPT RR in wrong section, ignoring."); | |
2233 | bad_opt = true; | |
2234 | continue; | |
2235 | } | |
2236 | ||
2237 | if (!opt_is_good(rr, &has_rfc6975)) { | |
2238 | log_debug("Malformed OPT RR, ignoring."); | |
2239 | bad_opt = true; | |
2240 | continue; | |
2241 | } | |
2242 | ||
2243 | if (DNS_PACKET_QR(p)) { | |
2244 | /* Additional checks for responses */ | |
2245 | ||
2246 | if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr)) { | |
2247 | /* If this is a reply and we don't know the EDNS version | |
2248 | * then something is weird... */ | |
2249 | log_debug("EDNS version newer that our request, bad server."); | |
2250 | return -EBADMSG; | |
2251 | } | |
2252 | ||
2253 | if (has_rfc6975) { | |
2254 | /* If the OPT RR contains RFC6975 algorithm data, then this | |
2255 | * is indication that the server just copied the OPT it got | |
2256 | * from us (which contained that data) back into the reply. | |
2257 | * If so, then it doesn't properly support EDNS, as RFC6975 | |
2258 | * makes it very clear that the algorithm data should only | |
2259 | * be contained in questions, never in replies. Crappy | |
2260 | * Belkin routers copy the OPT data for example, hence let's | |
2261 | * detect this so that we downgrade early. */ | |
2262 | log_debug("OPT RR contains RFC6975 data, ignoring."); | |
2263 | bad_opt = true; | |
2264 | continue; | |
2265 | } | |
2266 | } | |
2267 | ||
2268 | p->opt = dns_resource_record_ref(rr); | |
2269 | } else { | |
2270 | /* According to RFC 4795, section 2.9. only the RRs from the Answer section | |
2271 | * shall be cached. Hence mark only those RRs as cacheable by default, but | |
2272 | * not the ones from the Additional or Authority sections. */ | |
2273 | DnsAnswerFlags flags = | |
2274 | (i < DNS_PACKET_ANCOUNT(p) ? DNS_ANSWER_CACHEABLE : 0) | | |
2275 | (p->protocol == DNS_PROTOCOL_MDNS && !cache_flush ? DNS_ANSWER_SHARED_OWNER : 0); | |
2276 | ||
2277 | r = dns_answer_add(answer, rr, p->ifindex, flags); | |
2278 | if (r < 0) | |
2279 | return r; | |
2280 | } | |
2281 | ||
2282 | /* Remember this RR, so that we potentically can merge it's ->key object with the | |
2283 | * next RR. Note that we only do this if we actually decided to keep the RR around. | |
2284 | */ | |
2285 | dns_resource_record_unref(previous); | |
2286 | previous = dns_resource_record_ref(rr); | |
2287 | } | |
2288 | ||
2289 | if (bad_opt) | |
2290 | p->opt = dns_resource_record_unref(p->opt); | |
2291 | ||
2292 | *ret_answer = TAKE_PTR(answer); | |
2293 | ||
2294 | return 0; | |
2295 | } | |
2296 | ||
2297 | int dns_packet_extract(DnsPacket *p) { | |
2298 | _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL; | |
2299 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; | |
2300 | _cleanup_(rewind_dns_packet) DnsPacketRewinder rewinder = {}; | |
2301 | int r; | |
2302 | ||
2303 | if (p->extracted) | |
2304 | return 0; | |
2305 | ||
2306 | INIT_REWINDER(rewinder, p); | |
2307 | dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE); | |
2308 | ||
2309 | r = dns_packet_extract_question(p, &question); | |
2310 | if (r < 0) | |
2311 | return r; | |
2312 | ||
2313 | r = dns_packet_extract_answer(p, &answer); | |
2314 | if (r < 0) | |
2315 | return r; | |
2316 | ||
2317 | p->question = TAKE_PTR(question); | |
2318 | p->answer = TAKE_PTR(answer); | |
2319 | ||
2320 | p->extracted = true; | |
2321 | ||
2322 | /* no CANCEL, always rewind */ | |
2323 | return 0; | |
2324 | } | |
2325 | ||
2326 | int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key) { | |
2327 | int r; | |
2328 | ||
2329 | assert(p); | |
2330 | assert(key); | |
2331 | ||
2332 | /* Checks if the specified packet is a reply for the specified | |
2333 | * key and the specified key is the only one in the question | |
2334 | * section. */ | |
2335 | ||
2336 | if (DNS_PACKET_QR(p) != 1) | |
2337 | return 0; | |
2338 | ||
2339 | /* Let's unpack the packet, if that hasn't happened yet. */ | |
2340 | r = dns_packet_extract(p); | |
2341 | if (r < 0) | |
2342 | return r; | |
2343 | ||
2344 | if (!p->question) | |
2345 | return 0; | |
2346 | ||
2347 | if (p->question->n_keys != 1) | |
2348 | return 0; | |
2349 | ||
2350 | return dns_resource_key_equal(p->question->keys[0], key); | |
2351 | } | |
2352 | ||
2353 | static void dns_packet_hash_func(const DnsPacket *s, struct siphash *state) { | |
2354 | assert(s); | |
2355 | ||
2356 | siphash24_compress(&s->size, sizeof(s->size), state); | |
2357 | siphash24_compress(DNS_PACKET_DATA((DnsPacket*) s), s->size, state); | |
2358 | } | |
2359 | ||
2360 | static int dns_packet_compare_func(const DnsPacket *x, const DnsPacket *y) { | |
2361 | int r; | |
2362 | ||
2363 | r = CMP(x->size, y->size); | |
2364 | if (r != 0) | |
2365 | return r; | |
2366 | ||
2367 | return memcmp(DNS_PACKET_DATA((DnsPacket*) x), DNS_PACKET_DATA((DnsPacket*) y), x->size); | |
2368 | } | |
2369 | ||
2370 | DEFINE_HASH_OPS(dns_packet_hash_ops, DnsPacket, dns_packet_hash_func, dns_packet_compare_func); | |
2371 | ||
2372 | static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = { | |
2373 | [DNS_RCODE_SUCCESS] = "SUCCESS", | |
2374 | [DNS_RCODE_FORMERR] = "FORMERR", | |
2375 | [DNS_RCODE_SERVFAIL] = "SERVFAIL", | |
2376 | [DNS_RCODE_NXDOMAIN] = "NXDOMAIN", | |
2377 | [DNS_RCODE_NOTIMP] = "NOTIMP", | |
2378 | [DNS_RCODE_REFUSED] = "REFUSED", | |
2379 | [DNS_RCODE_YXDOMAIN] = "YXDOMAIN", | |
2380 | [DNS_RCODE_YXRRSET] = "YRRSET", | |
2381 | [DNS_RCODE_NXRRSET] = "NXRRSET", | |
2382 | [DNS_RCODE_NOTAUTH] = "NOTAUTH", | |
2383 | [DNS_RCODE_NOTZONE] = "NOTZONE", | |
2384 | [DNS_RCODE_BADVERS] = "BADVERS", | |
2385 | [DNS_RCODE_BADKEY] = "BADKEY", | |
2386 | [DNS_RCODE_BADTIME] = "BADTIME", | |
2387 | [DNS_RCODE_BADMODE] = "BADMODE", | |
2388 | [DNS_RCODE_BADNAME] = "BADNAME", | |
2389 | [DNS_RCODE_BADALG] = "BADALG", | |
2390 | [DNS_RCODE_BADTRUNC] = "BADTRUNC", | |
2391 | [DNS_RCODE_BADCOOKIE] = "BADCOOKIE", | |
2392 | }; | |
2393 | DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int); | |
2394 | ||
2395 | static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = { | |
2396 | [DNS_PROTOCOL_DNS] = "dns", | |
2397 | [DNS_PROTOCOL_MDNS] = "mdns", | |
2398 | [DNS_PROTOCOL_LLMNR] = "llmnr", | |
2399 | }; | |
2400 | DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol); |