1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
7 #include "alloc-util.h"
8 #include "dns-domain.h"
9 #include "memory-util.h"
10 #include "resolved-dns-packet.h"
12 #include "stdio-util.h"
13 #include "string-table.h"
15 #include "unaligned.h"
19 #define EDNS0_OPT_DO (1<<15)
21 assert_cc(DNS_PACKET_SIZE_START
> DNS_PACKET_HEADER_SIZE
);
23 typedef struct DnsPacketRewinder
{
28 static void rewind_dns_packet(DnsPacketRewinder
*rewinder
) {
30 dns_packet_rewind(rewinder
->packet
, rewinder
->saved_rindex
);
33 #define REWINDER_INIT(p) { \
35 .saved_rindex = (p)->rindex, \
37 #define CANCEL_REWINDER(rewinder) do { (rewinder).packet = NULL; } while (0)
42 size_t min_alloc_dsize
,
49 assert(max_size
>= DNS_PACKET_HEADER_SIZE
);
51 if (max_size
> DNS_PACKET_SIZE_MAX
)
52 max_size
= DNS_PACKET_SIZE_MAX
;
54 /* The caller may not check what is going to be truly allocated, so do not allow to
55 * allocate a DNS packet bigger than DNS_PACKET_SIZE_MAX.
57 if (min_alloc_dsize
> DNS_PACKET_SIZE_MAX
)
58 return log_error_errno(SYNTHETIC_ERRNO(EFBIG
),
59 "Requested packet data size too big: %zu",
62 /* When dns_packet_new() is called with min_alloc_dsize == 0, allocate more than the
63 * absolute minimum (which is the dns packet header size), to avoid
64 * resizing immediately again after appending the first data to the packet.
66 if (min_alloc_dsize
< DNS_PACKET_HEADER_SIZE
)
67 a
= DNS_PACKET_SIZE_START
;
71 /* round up to next page size */
72 a
= PAGE_ALIGN(ALIGN(sizeof(DnsPacket
)) + a
) - ALIGN(sizeof(DnsPacket
));
74 /* make sure we never allocate more than useful */
78 p
= malloc0(ALIGN(sizeof(DnsPacket
)) + a
);
85 .size
= DNS_PACKET_HEADER_SIZE
,
86 .rindex
= DNS_PACKET_HEADER_SIZE
,
89 .opt_start
= SIZE_MAX
,
98 void dns_packet_set_flags(DnsPacket
*p
, bool dnssec_checking_disabled
, bool truncated
) {
104 h
= DNS_PACKET_HEADER(p
);
106 switch (p
->protocol
) {
107 case DNS_PROTOCOL_LLMNR
:
110 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
121 case DNS_PROTOCOL_MDNS
:
122 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
126 0 /* rd (ask for recursion) */,
136 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
140 1 /* rd (ask for recursion) */,
143 dnssec_checking_disabled
/* cd */,
148 int dns_packet_new_query(DnsPacket
**ret
, DnsProtocol protocol
, size_t min_alloc_dsize
, bool dnssec_checking_disabled
) {
154 r
= dns_packet_new(&p
, protocol
, min_alloc_dsize
, DNS_PACKET_SIZE_MAX
);
158 /* Always set the TC bit to 0 initially.
159 * If there are multiple packets later, we'll update the bit shortly before sending.
161 dns_packet_set_flags(p
, dnssec_checking_disabled
, false);
167 int dns_packet_dup(DnsPacket
**ret
, DnsPacket
*p
) {
174 r
= dns_packet_validate(p
);
178 c
= malloc(ALIGN(sizeof(DnsPacket
)) + p
->size
);
184 .protocol
= p
->protocol
,
186 .rindex
= DNS_PACKET_HEADER_SIZE
,
187 .allocated
= p
->size
,
188 .max_size
= p
->max_size
,
189 .opt_start
= SIZE_MAX
,
190 .opt_size
= SIZE_MAX
,
193 memcpy(DNS_PACKET_DATA(c
), DNS_PACKET_DATA(p
), p
->size
);
199 DnsPacket
*dns_packet_ref(DnsPacket
*p
) {
204 assert(!p
->on_stack
);
206 assert(p
->n_ref
> 0);
211 static void dns_packet_free(DnsPacket
*p
) {
216 dns_question_unref(p
->question
);
217 dns_answer_unref(p
->answer
);
218 dns_resource_record_unref(p
->opt
);
220 while ((s
= hashmap_steal_first_key(p
->names
)))
222 hashmap_free(p
->names
);
230 DnsPacket
*dns_packet_unref(DnsPacket
*p
) {
234 assert(p
->n_ref
> 0);
236 dns_packet_unref(p
->more
);
246 int dns_packet_validate(DnsPacket
*p
) {
249 if (p
->size
< DNS_PACKET_HEADER_SIZE
)
252 if (p
->size
> DNS_PACKET_SIZE_MAX
)
258 int dns_packet_validate_reply(DnsPacket
*p
) {
263 r
= dns_packet_validate(p
);
267 if (DNS_PACKET_QR(p
) != 1)
270 if (DNS_PACKET_OPCODE(p
) != 0)
273 switch (p
->protocol
) {
275 case DNS_PROTOCOL_LLMNR
:
276 /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
277 if (DNS_PACKET_QDCOUNT(p
) != 1)
282 case DNS_PROTOCOL_MDNS
:
283 /* RFC 6762, Section 18 */
284 if (DNS_PACKET_RCODE(p
) != 0)
296 int dns_packet_validate_query(DnsPacket
*p
) {
301 r
= dns_packet_validate(p
);
305 if (DNS_PACKET_QR(p
) != 0)
308 if (DNS_PACKET_OPCODE(p
) != 0)
311 if (DNS_PACKET_TC(p
))
314 switch (p
->protocol
) {
316 case DNS_PROTOCOL_LLMNR
:
317 case DNS_PROTOCOL_DNS
:
318 /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
319 if (DNS_PACKET_QDCOUNT(p
) != 1)
322 /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
323 if (DNS_PACKET_ANCOUNT(p
) > 0)
326 /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
327 if (DNS_PACKET_NSCOUNT(p
) > 0)
332 case DNS_PROTOCOL_MDNS
:
333 /* RFC 6762, Section 18 specifies that messages with non-zero RCODE
334 * must be silently ignored, and that we must ignore the values of
335 * AA, RD, RA, AD, and CD bits. */
336 if (DNS_PACKET_RCODE(p
) != 0)
348 static int dns_packet_extend(DnsPacket
*p
, size_t add
, void **ret
, size_t *start
) {
351 if (p
->size
+ add
> p
->allocated
) {
354 a
= PAGE_ALIGN((p
->size
+ add
) * 2);
356 ms
= dns_packet_size_max(p
);
360 if (p
->size
+ add
> a
)
366 d
= realloc(p
->_data
, a
);
372 p
->_data
= malloc(a
);
376 memcpy(p
->_data
, (uint8_t*) p
+ ALIGN(sizeof(DnsPacket
)), p
->size
);
377 memzero((uint8_t*) p
->_data
+ p
->size
, a
- p
->size
);
387 *ret
= (uint8_t*) DNS_PACKET_DATA(p
) + p
->size
;
393 void dns_packet_truncate(DnsPacket
*p
, size_t sz
) {
402 HASHMAP_FOREACH_KEY(n
, s
, p
->names
) {
404 if (PTR_TO_SIZE(n
) < sz
)
407 hashmap_remove(p
->names
, s
);
414 int dns_packet_append_blob(DnsPacket
*p
, const void *d
, size_t l
, size_t *start
) {
420 r
= dns_packet_extend(p
, l
, &q
, start
);
424 memcpy_safe(q
, d
, l
);
428 int dns_packet_append_uint8(DnsPacket
*p
, uint8_t v
, size_t *start
) {
434 r
= dns_packet_extend(p
, sizeof(uint8_t), &d
, start
);
438 ((uint8_t*) d
)[0] = v
;
443 int dns_packet_append_uint16(DnsPacket
*p
, uint16_t v
, size_t *start
) {
449 r
= dns_packet_extend(p
, sizeof(uint16_t), &d
, start
);
453 unaligned_write_be16(d
, v
);
458 int dns_packet_append_uint32(DnsPacket
*p
, uint32_t v
, size_t *start
) {
464 r
= dns_packet_extend(p
, sizeof(uint32_t), &d
, start
);
468 unaligned_write_be32(d
, v
);
473 int dns_packet_append_string(DnsPacket
*p
, const char *s
, size_t *start
) {
477 return dns_packet_append_raw_string(p
, s
, strlen(s
), start
);
480 int dns_packet_append_raw_string(DnsPacket
*p
, const void *s
, size_t size
, size_t *start
) {
485 assert(s
|| size
== 0);
490 r
= dns_packet_extend(p
, 1 + size
, &d
, start
);
494 ((uint8_t*) d
)[0] = (uint8_t) size
;
496 memcpy_safe(((uint8_t*) d
) + 1, s
, size
);
501 int dns_packet_append_label(DnsPacket
*p
, const char *d
, size_t l
, bool canonical_candidate
, size_t *start
) {
505 /* Append a label to a packet. Optionally, does this in DNSSEC
506 * canonical form, if this label is marked as a candidate for
507 * it, and the canonical form logic is enabled for the
513 if (l
> DNS_LABEL_MAX
)
516 r
= dns_packet_extend(p
, 1 + l
, (void**) &w
, start
);
520 *(w
++) = (uint8_t) l
;
522 if (p
->canonical_form
&& canonical_candidate
)
523 /* Generate in canonical form, as defined by DNSSEC
524 * RFC 4034, Section 6.2, i.e. all lower-case. */
525 for (size_t i
= 0; i
< l
; i
++)
526 w
[i
] = (uint8_t) ascii_tolower(d
[i
]);
528 /* Otherwise, just copy the string unaltered. This is
529 * essential for DNS-SD, where the casing of labels
530 * matters and needs to be retained. */
536 int dns_packet_append_name(
539 bool allow_compression
,
540 bool canonical_candidate
,
549 if (p
->refuse_compression
)
550 allow_compression
= false;
552 saved_size
= p
->size
;
554 while (!dns_name_is_root(name
)) {
555 const char *z
= name
;
556 char label
[DNS_LABEL_MAX
];
559 if (allow_compression
)
560 n
= PTR_TO_SIZE(hashmap_get(p
->names
, name
));
565 r
= dns_packet_append_uint16(p
, 0xC000 | n
, NULL
);
573 r
= dns_label_unescape(&name
, label
, sizeof label
, 0);
577 r
= dns_packet_append_label(p
, label
, r
, canonical_candidate
, &n
);
581 if (allow_compression
) {
582 _cleanup_free_
char *s
= NULL
;
590 r
= hashmap_ensure_put(&p
->names
, &dns_name_hash_ops
, s
, SIZE_TO_PTR(n
));
598 r
= dns_packet_append_uint8(p
, 0, NULL
);
609 dns_packet_truncate(p
, saved_size
);
613 int dns_packet_append_key(DnsPacket
*p
, const DnsResourceKey
*k
, const DnsAnswerFlags flags
, size_t *start
) {
621 saved_size
= p
->size
;
623 r
= dns_packet_append_name(p
, dns_resource_key_name(k
), true, true, NULL
);
627 r
= dns_packet_append_uint16(p
, k
->type
, NULL
);
631 class = flags
& DNS_ANSWER_CACHE_FLUSH
? k
->class | MDNS_RR_CACHE_FLUSH_OR_QU
: k
->class;
632 r
= dns_packet_append_uint16(p
, class, NULL
);
642 dns_packet_truncate(p
, saved_size
);
646 static int dns_packet_append_type_window(DnsPacket
*p
, uint8_t window
, uint8_t length
, const uint8_t *types
, size_t *start
) {
654 saved_size
= p
->size
;
656 r
= dns_packet_append_uint8(p
, window
, NULL
);
660 r
= dns_packet_append_uint8(p
, length
, NULL
);
664 r
= dns_packet_append_blob(p
, types
, length
, NULL
);
673 dns_packet_truncate(p
, saved_size
);
677 static int dns_packet_append_types(DnsPacket
*p
, Bitmap
*types
, size_t *start
) {
680 uint8_t bitmaps
[32] = {};
687 saved_size
= p
->size
;
689 BITMAP_FOREACH(n
, types
) {
692 if ((n
>> 8) != window
&& bitmaps
[entry
/ 8] != 0) {
693 r
= dns_packet_append_type_window(p
, window
, entry
/ 8 + 1, bitmaps
, NULL
);
703 bitmaps
[entry
/ 8] |= 1 << (7 - (entry
% 8));
706 if (bitmaps
[entry
/ 8] != 0) {
707 r
= dns_packet_append_type_window(p
, window
, entry
/ 8 + 1, bitmaps
, NULL
);
717 dns_packet_truncate(p
, saved_size
);
721 /* Append the OPT pseudo-RR described in RFC6891 */
722 int dns_packet_append_opt(
724 uint16_t max_udp_size
,
726 bool include_rfc6975
,
735 /* we must never advertise supported packet size smaller than the legacy max */
736 assert(max_udp_size
>= DNS_PACKET_UNICAST_SIZE_MAX
);
738 assert(rcode
<= _DNS_RCODE_MAX
);
740 if (p
->opt_start
!= SIZE_MAX
)
743 assert(p
->opt_size
== SIZE_MAX
);
745 saved_size
= p
->size
;
748 r
= dns_packet_append_uint8(p
, 0, NULL
);
753 r
= dns_packet_append_uint16(p
, DNS_TYPE_OPT
, NULL
);
757 /* class: maximum udp packet that can be received */
758 r
= dns_packet_append_uint16(p
, max_udp_size
, NULL
);
762 /* extended RCODE and VERSION */
763 r
= dns_packet_append_uint16(p
, ((uint16_t) rcode
& 0x0FF0) << 4, NULL
);
767 /* flags: DNSSEC OK (DO), see RFC3225 */
768 r
= dns_packet_append_uint16(p
, edns0_do
? EDNS0_OPT_DO
: 0, NULL
);
772 if (edns0_do
&& include_rfc6975
) {
773 /* If DO is on and this is requested, also append RFC6975 Algorithm data. This is supposed to
774 * be done on queries, not on replies, hencer callers should turn this off when finishing off
777 static const uint8_t rfc6975
[] = {
779 0, 5, /* OPTION_CODE: DAU */
780 #if PREFER_OPENSSL || (HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600)
781 0, 7, /* LIST_LENGTH */
783 0, 6, /* LIST_LENGTH */
785 DNSSEC_ALGORITHM_RSASHA1
,
786 DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1
,
787 DNSSEC_ALGORITHM_RSASHA256
,
788 DNSSEC_ALGORITHM_RSASHA512
,
789 DNSSEC_ALGORITHM_ECDSAP256SHA256
,
790 DNSSEC_ALGORITHM_ECDSAP384SHA384
,
791 #if PREFER_OPENSSL || (HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600)
792 DNSSEC_ALGORITHM_ED25519
,
795 0, 6, /* OPTION_CODE: DHU */
796 0, 3, /* LIST_LENGTH */
798 DNSSEC_DIGEST_SHA256
,
799 DNSSEC_DIGEST_SHA384
,
801 0, 7, /* OPTION_CODE: N3U */
802 0, 1, /* LIST_LENGTH */
803 NSEC3_ALGORITHM_SHA1
,
806 r
= dns_packet_append_uint16(p
, sizeof(rfc6975
), NULL
); /* RDLENGTH */
810 r
= dns_packet_append_blob(p
, rfc6975
, sizeof(rfc6975
), NULL
); /* the payload, as defined above */
814 if (strlen(nsid
) > UINT16_MAX
- 4) {
819 r
= dns_packet_append_uint16(p
, 4 + strlen(nsid
), NULL
); /* RDLENGTH */
823 r
= dns_packet_append_uint16(p
, 3, NULL
); /* OPTION-CODE: NSID */
827 r
= dns_packet_append_uint16(p
, strlen(nsid
), NULL
); /* OPTION-LENGTH */
831 r
= dns_packet_append_blob(p
, nsid
, strlen(nsid
), NULL
);
833 r
= dns_packet_append_uint16(p
, 0, NULL
);
837 DNS_PACKET_HEADER(p
)->arcount
= htobe16(DNS_PACKET_ARCOUNT(p
) + 1);
839 p
->opt_start
= saved_size
;
840 p
->opt_size
= p
->size
- saved_size
;
843 *ret_start
= saved_size
;
848 dns_packet_truncate(p
, saved_size
);
852 int dns_packet_truncate_opt(DnsPacket
*p
) {
855 if (p
->opt_start
== SIZE_MAX
) {
856 assert(p
->opt_size
== SIZE_MAX
);
860 assert(p
->opt_size
!= SIZE_MAX
);
861 assert(DNS_PACKET_ARCOUNT(p
) > 0);
863 if (p
->opt_start
+ p
->opt_size
!= p
->size
)
866 dns_packet_truncate(p
, p
->opt_start
);
867 DNS_PACKET_HEADER(p
)->arcount
= htobe16(DNS_PACKET_ARCOUNT(p
) - 1);
868 p
->opt_start
= p
->opt_size
= SIZE_MAX
;
873 int dns_packet_append_rr(DnsPacket
*p
, const DnsResourceRecord
*rr
, const DnsAnswerFlags flags
, size_t *start
, size_t *rdata_start
) {
875 size_t saved_size
, rdlength_offset
, end
, rdlength
, rds
;
882 saved_size
= p
->size
;
884 r
= dns_packet_append_key(p
, rr
->key
, flags
, NULL
);
888 ttl
= flags
& DNS_ANSWER_GOODBYE
? 0 : rr
->ttl
;
889 r
= dns_packet_append_uint32(p
, ttl
, NULL
);
893 /* Initially we write 0 here */
894 r
= dns_packet_append_uint16(p
, 0, &rdlength_offset
);
898 rds
= p
->size
- saved_size
;
900 switch (rr
->unparsable
? _DNS_TYPE_INVALID
: rr
->key
->type
) {
903 r
= dns_packet_append_uint16(p
, rr
->srv
.priority
, NULL
);
907 r
= dns_packet_append_uint16(p
, rr
->srv
.weight
, NULL
);
911 r
= dns_packet_append_uint16(p
, rr
->srv
.port
, NULL
);
915 /* RFC 2782 states "Unless and until permitted by future standards
916 * action, name compression is not to be used for this field." */
917 r
= dns_packet_append_name(p
, rr
->srv
.name
, false, true, NULL
);
924 r
= dns_packet_append_name(p
, rr
->ptr
.name
, true, true, NULL
);
928 r
= dns_packet_append_string(p
, rr
->hinfo
.cpu
, NULL
);
932 r
= dns_packet_append_string(p
, rr
->hinfo
.os
, NULL
);
935 case DNS_TYPE_SPF
: /* exactly the same as TXT */
938 if (!rr
->txt
.items
) {
939 /* RFC 6763, section 6.1 suggests to generate
940 * single empty string for an empty array. */
942 r
= dns_packet_append_raw_string(p
, NULL
, 0, NULL
);
946 LIST_FOREACH(items
, i
, rr
->txt
.items
) {
947 r
= dns_packet_append_raw_string(p
, i
->data
, i
->length
, NULL
);
956 r
= dns_packet_append_blob(p
, &rr
->a
.in_addr
, sizeof(struct in_addr
), NULL
);
960 r
= dns_packet_append_blob(p
, &rr
->aaaa
.in6_addr
, sizeof(struct in6_addr
), NULL
);
964 r
= dns_packet_append_name(p
, rr
->soa
.mname
, true, true, NULL
);
968 r
= dns_packet_append_name(p
, rr
->soa
.rname
, true, true, NULL
);
972 r
= dns_packet_append_uint32(p
, rr
->soa
.serial
, NULL
);
976 r
= dns_packet_append_uint32(p
, rr
->soa
.refresh
, NULL
);
980 r
= dns_packet_append_uint32(p
, rr
->soa
.retry
, NULL
);
984 r
= dns_packet_append_uint32(p
, rr
->soa
.expire
, NULL
);
988 r
= dns_packet_append_uint32(p
, rr
->soa
.minimum
, NULL
);
992 r
= dns_packet_append_uint16(p
, rr
->mx
.priority
, NULL
);
996 r
= dns_packet_append_name(p
, rr
->mx
.exchange
, true, true, NULL
);
1000 r
= dns_packet_append_uint8(p
, rr
->loc
.version
, NULL
);
1004 r
= dns_packet_append_uint8(p
, rr
->loc
.size
, NULL
);
1008 r
= dns_packet_append_uint8(p
, rr
->loc
.horiz_pre
, NULL
);
1012 r
= dns_packet_append_uint8(p
, rr
->loc
.vert_pre
, NULL
);
1016 r
= dns_packet_append_uint32(p
, rr
->loc
.latitude
, NULL
);
1020 r
= dns_packet_append_uint32(p
, rr
->loc
.longitude
, NULL
);
1024 r
= dns_packet_append_uint32(p
, rr
->loc
.altitude
, NULL
);
1028 r
= dns_packet_append_uint16(p
, rr
->ds
.key_tag
, NULL
);
1032 r
= dns_packet_append_uint8(p
, rr
->ds
.algorithm
, NULL
);
1036 r
= dns_packet_append_uint8(p
, rr
->ds
.digest_type
, NULL
);
1040 r
= dns_packet_append_blob(p
, rr
->ds
.digest
, rr
->ds
.digest_size
, NULL
);
1043 case DNS_TYPE_SSHFP
:
1044 r
= dns_packet_append_uint8(p
, rr
->sshfp
.algorithm
, NULL
);
1048 r
= dns_packet_append_uint8(p
, rr
->sshfp
.fptype
, NULL
);
1052 r
= dns_packet_append_blob(p
, rr
->sshfp
.fingerprint
, rr
->sshfp
.fingerprint_size
, NULL
);
1055 case DNS_TYPE_DNSKEY
:
1056 r
= dns_packet_append_uint16(p
, rr
->dnskey
.flags
, NULL
);
1060 r
= dns_packet_append_uint8(p
, rr
->dnskey
.protocol
, NULL
);
1064 r
= dns_packet_append_uint8(p
, rr
->dnskey
.algorithm
, NULL
);
1068 r
= dns_packet_append_blob(p
, rr
->dnskey
.key
, rr
->dnskey
.key_size
, NULL
);
1071 case DNS_TYPE_RRSIG
:
1072 r
= dns_packet_append_uint16(p
, rr
->rrsig
.type_covered
, NULL
);
1076 r
= dns_packet_append_uint8(p
, rr
->rrsig
.algorithm
, NULL
);
1080 r
= dns_packet_append_uint8(p
, rr
->rrsig
.labels
, NULL
);
1084 r
= dns_packet_append_uint32(p
, rr
->rrsig
.original_ttl
, NULL
);
1088 r
= dns_packet_append_uint32(p
, rr
->rrsig
.expiration
, NULL
);
1092 r
= dns_packet_append_uint32(p
, rr
->rrsig
.inception
, NULL
);
1096 r
= dns_packet_append_uint16(p
, rr
->rrsig
.key_tag
, NULL
);
1100 r
= dns_packet_append_name(p
, rr
->rrsig
.signer
, false, true, NULL
);
1104 r
= dns_packet_append_blob(p
, rr
->rrsig
.signature
, rr
->rrsig
.signature_size
, NULL
);
1108 r
= dns_packet_append_name(p
, rr
->nsec
.next_domain_name
, false, false, NULL
);
1112 r
= dns_packet_append_types(p
, rr
->nsec
.types
, NULL
);
1118 case DNS_TYPE_NSEC3
:
1119 r
= dns_packet_append_uint8(p
, rr
->nsec3
.algorithm
, NULL
);
1123 r
= dns_packet_append_uint8(p
, rr
->nsec3
.flags
, NULL
);
1127 r
= dns_packet_append_uint16(p
, rr
->nsec3
.iterations
, NULL
);
1131 r
= dns_packet_append_uint8(p
, rr
->nsec3
.salt_size
, NULL
);
1135 r
= dns_packet_append_blob(p
, rr
->nsec3
.salt
, rr
->nsec3
.salt_size
, NULL
);
1139 r
= dns_packet_append_uint8(p
, rr
->nsec3
.next_hashed_name_size
, NULL
);
1143 r
= dns_packet_append_blob(p
, rr
->nsec3
.next_hashed_name
, rr
->nsec3
.next_hashed_name_size
, NULL
);
1147 r
= dns_packet_append_types(p
, rr
->nsec3
.types
, NULL
);
1154 r
= dns_packet_append_uint8(p
, rr
->tlsa
.cert_usage
, NULL
);
1158 r
= dns_packet_append_uint8(p
, rr
->tlsa
.selector
, NULL
);
1162 r
= dns_packet_append_uint8(p
, rr
->tlsa
.matching_type
, NULL
);
1166 r
= dns_packet_append_blob(p
, rr
->tlsa
.data
, rr
->tlsa
.data_size
, NULL
);
1170 r
= dns_packet_append_uint8(p
, rr
->caa
.flags
, NULL
);
1174 r
= dns_packet_append_string(p
, rr
->caa
.tag
, NULL
);
1178 r
= dns_packet_append_blob(p
, rr
->caa
.value
, rr
->caa
.value_size
, NULL
);
1182 case DNS_TYPE_OPENPGPKEY
:
1183 case _DNS_TYPE_INVALID
: /* unparsable */
1186 r
= dns_packet_append_blob(p
, rr
->generic
.data
, rr
->generic
.data_size
, NULL
);
1192 /* Let's calculate the actual data size and update the field */
1193 rdlength
= p
->size
- rdlength_offset
- sizeof(uint16_t);
1194 if (rdlength
> 0xFFFF) {
1200 p
->size
= rdlength_offset
;
1201 r
= dns_packet_append_uint16(p
, rdlength
, NULL
);
1207 *start
= saved_size
;
1215 dns_packet_truncate(p
, saved_size
);
1219 int dns_packet_append_question(DnsPacket
*p
, DnsQuestion
*q
) {
1220 DnsResourceKey
*key
;
1225 DNS_QUESTION_FOREACH(key
, q
) {
1226 r
= dns_packet_append_key(p
, key
, 0, NULL
);
1234 int dns_packet_append_answer(DnsPacket
*p
, DnsAnswer
*a
, unsigned *completed
) {
1235 DnsResourceRecord
*rr
;
1236 DnsAnswerFlags flags
;
1241 DNS_ANSWER_FOREACH_FLAGS(rr
, flags
, a
) {
1242 r
= dns_packet_append_rr(p
, rr
, flags
, NULL
, NULL
);
1253 int dns_packet_read(DnsPacket
*p
, size_t sz
, const void **ret
, size_t *start
) {
1255 assert(p
->rindex
<= p
->size
);
1257 if (sz
> p
->size
- p
->rindex
)
1261 *ret
= (uint8_t*) DNS_PACKET_DATA(p
) + p
->rindex
;
1270 void dns_packet_rewind(DnsPacket
*p
, size_t idx
) {
1272 assert(idx
<= p
->size
);
1273 assert(idx
>= DNS_PACKET_HEADER_SIZE
);
1278 int dns_packet_read_blob(DnsPacket
*p
, void *d
, size_t sz
, size_t *start
) {
1285 r
= dns_packet_read(p
, sz
, &q
, start
);
1293 static int dns_packet_read_memdup(
1294 DnsPacket
*p
, size_t size
,
1295 void **ret
, size_t *ret_size
,
1296 size_t *ret_start
) {
1305 r
= dns_packet_read(p
, size
, &src
, &start
);
1314 copy
= memdup(src
, size
);
1329 int dns_packet_read_uint8(DnsPacket
*p
, uint8_t *ret
, size_t *start
) {
1335 r
= dns_packet_read(p
, sizeof(uint8_t), &d
, start
);
1339 *ret
= ((uint8_t*) d
)[0];
1343 int dns_packet_read_uint16(DnsPacket
*p
, uint16_t *ret
, size_t *start
) {
1349 r
= dns_packet_read(p
, sizeof(uint16_t), &d
, start
);
1354 *ret
= unaligned_read_be16(d
);
1359 int dns_packet_read_uint32(DnsPacket
*p
, uint32_t *ret
, size_t *start
) {
1365 r
= dns_packet_read(p
, sizeof(uint32_t), &d
, start
);
1369 *ret
= unaligned_read_be32(d
);
1374 int dns_packet_read_string(DnsPacket
*p
, char **ret
, size_t *start
) {
1377 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1383 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1387 r
= dns_packet_read(p
, c
, &d
, NULL
);
1391 if (memchr(d
, 0, c
))
1394 t
= memdup_suffix0(d
, c
);
1398 if (!utf8_is_valid(t
)) {
1406 *start
= rewinder
.saved_rindex
;
1407 CANCEL_REWINDER(rewinder
);
1412 int dns_packet_read_raw_string(DnsPacket
*p
, const void **ret
, size_t *size
, size_t *start
) {
1415 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1419 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1423 r
= dns_packet_read(p
, c
, ret
, NULL
);
1430 *start
= rewinder
.saved_rindex
;
1431 CANCEL_REWINDER(rewinder
);
1436 int dns_packet_read_name(
1439 bool allow_compression
,
1440 size_t *ret_start
) {
1444 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1445 size_t after_rindex
= 0, jump_barrier
= p
->rindex
;
1446 _cleanup_free_
char *name
= NULL
;
1451 if (p
->refuse_compression
)
1452 allow_compression
= false;
1457 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1468 r
= dns_packet_read(p
, c
, (const void**) &label
, NULL
);
1472 if (!GREEDY_REALLOC(name
, n
+ !first
+ DNS_LABEL_ESCAPED_MAX
))
1480 r
= dns_label_escape(label
, c
, name
+ n
, DNS_LABEL_ESCAPED_MAX
);
1486 } else if (allow_compression
&& FLAGS_SET(c
, 0xc0)) {
1490 r
= dns_packet_read_uint8(p
, &d
, NULL
);
1494 ptr
= (uint16_t) (c
& ~0xc0) << 8 | (uint16_t) d
;
1495 if (ptr
< DNS_PACKET_HEADER_SIZE
|| ptr
>= jump_barrier
)
1498 if (after_rindex
== 0)
1499 after_rindex
= p
->rindex
;
1501 /* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */
1508 if (!GREEDY_REALLOC(name
, n
+ 1))
1513 if (after_rindex
!= 0)
1514 p
->rindex
= after_rindex
;
1517 *ret
= TAKE_PTR(name
);
1519 *ret_start
= rewinder
.saved_rindex
;
1521 CANCEL_REWINDER(rewinder
);
1526 static int dns_packet_read_type_window(DnsPacket
*p
, Bitmap
**types
, size_t *start
) {
1530 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1531 uint8_t window
, length
;
1532 const uint8_t *bitmap
;
1537 r
= bitmap_ensure_allocated(types
);
1541 r
= dns_packet_read_uint8(p
, &window
, NULL
);
1545 r
= dns_packet_read_uint8(p
, &length
, NULL
);
1549 if (length
== 0 || length
> 32)
1552 r
= dns_packet_read(p
, length
, (const void **)&bitmap
, NULL
);
1556 for (uint8_t i
= 0; i
< length
; i
++) {
1557 uint8_t bitmask
= 1 << 7;
1567 for (; bitmask
; bit
++, bitmask
>>= 1)
1568 if (bitmap
[i
] & bitmask
) {
1571 n
= (uint16_t) window
<< 8 | (uint16_t) bit
;
1573 /* Ignore pseudo-types. see RFC4034 section 4.1.2 */
1574 if (dns_type_is_pseudo(n
))
1577 r
= bitmap_set(*types
, n
);
1587 *start
= rewinder
.saved_rindex
;
1588 CANCEL_REWINDER(rewinder
);
1593 static int dns_packet_read_type_windows(DnsPacket
*p
, Bitmap
**types
, size_t size
, size_t *start
) {
1594 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1597 while (p
->rindex
- rewinder
.saved_rindex
< size
) {
1598 r
= dns_packet_read_type_window(p
, types
, NULL
);
1602 assert(p
->rindex
>= rewinder
.saved_rindex
);
1604 /* don't read past end of current RR */
1605 if (p
->rindex
- rewinder
.saved_rindex
> size
)
1609 if (p
->rindex
- rewinder
.saved_rindex
!= size
)
1613 *start
= rewinder
.saved_rindex
;
1614 CANCEL_REWINDER(rewinder
);
1619 int dns_packet_read_key(
1621 DnsResourceKey
**ret
,
1622 bool *ret_cache_flush_or_qu
,
1623 size_t *ret_start
) {
1627 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1628 _cleanup_free_
char *name
= NULL
;
1629 bool cache_flush_or_qu
= false;
1630 uint16_t class, type
;
1633 r
= dns_packet_read_name(p
, &name
, true, NULL
);
1637 r
= dns_packet_read_uint16(p
, &type
, NULL
);
1641 r
= dns_packet_read_uint16(p
, &class, NULL
);
1645 if (p
->protocol
== DNS_PROTOCOL_MDNS
) {
1646 /* See RFC6762, sections 5.4 and 10.2 */
1648 if (type
!= DNS_TYPE_OPT
&& (class & MDNS_RR_CACHE_FLUSH_OR_QU
)) {
1649 class &= ~MDNS_RR_CACHE_FLUSH_OR_QU
;
1650 cache_flush_or_qu
= true;
1655 DnsResourceKey
*key
;
1657 key
= dns_resource_key_new_consume(class, type
, name
);
1665 if (ret_cache_flush_or_qu
)
1666 *ret_cache_flush_or_qu
= cache_flush_or_qu
;
1668 *ret_start
= rewinder
.saved_rindex
;
1670 CANCEL_REWINDER(rewinder
);
1674 static bool loc_size_ok(uint8_t size
) {
1675 uint8_t m
= size
>> 4, e
= size
& 0xF;
1677 return m
<= 9 && e
<= 9 && (m
> 0 || e
== 0);
1680 int dns_packet_read_rr(
1682 DnsResourceRecord
**ret
,
1683 bool *ret_cache_flush
,
1684 size_t *ret_start
) {
1688 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
1689 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
1690 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
1696 r
= dns_packet_read_key(p
, &key
, &cache_flush
, NULL
);
1700 if (!dns_class_is_valid_rr(key
->class) || !dns_type_is_valid_rr(key
->type
))
1703 rr
= dns_resource_record_new(key
);
1707 r
= dns_packet_read_uint32(p
, &rr
->ttl
, NULL
);
1711 /* RFC 2181, Section 8, suggests to
1712 * treat a TTL with the MSB set as a zero TTL. */
1713 if (rr
->ttl
& UINT32_C(0x80000000))
1716 r
= dns_packet_read_uint16(p
, &rdlength
, NULL
);
1720 if (rdlength
> p
->size
- p
->rindex
)
1725 switch (rr
->key
->type
) {
1728 r
= dns_packet_read_uint16(p
, &rr
->srv
.priority
, NULL
);
1731 r
= dns_packet_read_uint16(p
, &rr
->srv
.weight
, NULL
);
1734 r
= dns_packet_read_uint16(p
, &rr
->srv
.port
, NULL
);
1737 r
= dns_packet_read_name(p
, &rr
->srv
.name
, true, NULL
);
1742 case DNS_TYPE_CNAME
:
1743 case DNS_TYPE_DNAME
:
1744 r
= dns_packet_read_name(p
, &rr
->ptr
.name
, true, NULL
);
1747 case DNS_TYPE_HINFO
:
1748 r
= dns_packet_read_string(p
, &rr
->hinfo
.cpu
, NULL
);
1752 r
= dns_packet_read_string(p
, &rr
->hinfo
.os
, NULL
);
1755 case DNS_TYPE_SPF
: /* exactly the same as TXT */
1757 if (rdlength
<= 0) {
1758 r
= dns_txt_item_new_empty(&rr
->txt
.items
);
1762 DnsTxtItem
*last
= NULL
;
1764 while (p
->rindex
- offset
< rdlength
) {
1769 r
= dns_packet_read_raw_string(p
, &data
, &sz
, NULL
);
1773 i
= malloc0(offsetof(DnsTxtItem
, data
) + sz
+ 1); /* extra NUL byte at the end */
1777 memcpy(i
->data
, data
, sz
);
1780 LIST_INSERT_AFTER(items
, rr
->txt
.items
, last
, i
);
1789 r
= dns_packet_read_blob(p
, &rr
->a
.in_addr
, sizeof(struct in_addr
), NULL
);
1793 r
= dns_packet_read_blob(p
, &rr
->aaaa
.in6_addr
, sizeof(struct in6_addr
), NULL
);
1797 r
= dns_packet_read_name(p
, &rr
->soa
.mname
, true, NULL
);
1801 r
= dns_packet_read_name(p
, &rr
->soa
.rname
, true, NULL
);
1805 r
= dns_packet_read_uint32(p
, &rr
->soa
.serial
, NULL
);
1809 r
= dns_packet_read_uint32(p
, &rr
->soa
.refresh
, NULL
);
1813 r
= dns_packet_read_uint32(p
, &rr
->soa
.retry
, NULL
);
1817 r
= dns_packet_read_uint32(p
, &rr
->soa
.expire
, NULL
);
1821 r
= dns_packet_read_uint32(p
, &rr
->soa
.minimum
, NULL
);
1825 r
= dns_packet_read_uint16(p
, &rr
->mx
.priority
, NULL
);
1829 r
= dns_packet_read_name(p
, &rr
->mx
.exchange
, true, NULL
);
1832 case DNS_TYPE_LOC
: {
1836 r
= dns_packet_read_uint8(p
, &t
, &pos
);
1841 rr
->loc
.version
= t
;
1843 r
= dns_packet_read_uint8(p
, &rr
->loc
.size
, NULL
);
1847 if (!loc_size_ok(rr
->loc
.size
))
1850 r
= dns_packet_read_uint8(p
, &rr
->loc
.horiz_pre
, NULL
);
1854 if (!loc_size_ok(rr
->loc
.horiz_pre
))
1857 r
= dns_packet_read_uint8(p
, &rr
->loc
.vert_pre
, NULL
);
1861 if (!loc_size_ok(rr
->loc
.vert_pre
))
1864 r
= dns_packet_read_uint32(p
, &rr
->loc
.latitude
, NULL
);
1868 r
= dns_packet_read_uint32(p
, &rr
->loc
.longitude
, NULL
);
1872 r
= dns_packet_read_uint32(p
, &rr
->loc
.altitude
, NULL
);
1878 dns_packet_rewind(p
, pos
);
1879 rr
->unparsable
= true;
1885 r
= dns_packet_read_uint16(p
, &rr
->ds
.key_tag
, NULL
);
1889 r
= dns_packet_read_uint8(p
, &rr
->ds
.algorithm
, NULL
);
1893 r
= dns_packet_read_uint8(p
, &rr
->ds
.digest_type
, NULL
);
1900 r
= dns_packet_read_memdup(p
, rdlength
- 4,
1901 &rr
->ds
.digest
, &rr
->ds
.digest_size
,
1906 if (rr
->ds
.digest_size
<= 0)
1907 /* the accepted size depends on the algorithm, but for now
1908 just ensure that the value is greater than zero */
1913 case DNS_TYPE_SSHFP
:
1914 r
= dns_packet_read_uint8(p
, &rr
->sshfp
.algorithm
, NULL
);
1918 r
= dns_packet_read_uint8(p
, &rr
->sshfp
.fptype
, NULL
);
1925 r
= dns_packet_read_memdup(p
, rdlength
- 2,
1926 &rr
->sshfp
.fingerprint
, &rr
->sshfp
.fingerprint_size
,
1929 if (rr
->sshfp
.fingerprint_size
<= 0)
1930 /* the accepted size depends on the algorithm, but for now
1931 just ensure that the value is greater than zero */
1936 case DNS_TYPE_DNSKEY
:
1937 r
= dns_packet_read_uint16(p
, &rr
->dnskey
.flags
, NULL
);
1941 r
= dns_packet_read_uint8(p
, &rr
->dnskey
.protocol
, NULL
);
1945 r
= dns_packet_read_uint8(p
, &rr
->dnskey
.algorithm
, NULL
);
1952 r
= dns_packet_read_memdup(p
, rdlength
- 4,
1953 &rr
->dnskey
.key
, &rr
->dnskey
.key_size
,
1956 if (rr
->dnskey
.key_size
<= 0)
1957 /* the accepted size depends on the algorithm, but for now
1958 just ensure that the value is greater than zero */
1963 case DNS_TYPE_RRSIG
:
1964 r
= dns_packet_read_uint16(p
, &rr
->rrsig
.type_covered
, NULL
);
1968 r
= dns_packet_read_uint8(p
, &rr
->rrsig
.algorithm
, NULL
);
1972 r
= dns_packet_read_uint8(p
, &rr
->rrsig
.labels
, NULL
);
1976 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.original_ttl
, NULL
);
1980 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.expiration
, NULL
);
1984 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.inception
, NULL
);
1988 r
= dns_packet_read_uint16(p
, &rr
->rrsig
.key_tag
, NULL
);
1992 r
= dns_packet_read_name(p
, &rr
->rrsig
.signer
, false, NULL
);
1996 if (rdlength
< p
->rindex
- offset
)
1999 r
= dns_packet_read_memdup(p
, offset
+ rdlength
- p
->rindex
,
2000 &rr
->rrsig
.signature
, &rr
->rrsig
.signature_size
,
2003 if (rr
->rrsig
.signature_size
<= 0)
2004 /* the accepted size depends on the algorithm, but for now
2005 just ensure that the value is greater than zero */
2010 case DNS_TYPE_NSEC
: {
2013 * RFC6762, section 18.14 explicitly states mDNS should use name compression.
2014 * This contradicts RFC3845, section 2.1.1
2017 bool allow_compressed
= p
->protocol
== DNS_PROTOCOL_MDNS
;
2019 r
= dns_packet_read_name(p
, &rr
->nsec
.next_domain_name
, allow_compressed
, NULL
);
2023 if (rdlength
< p
->rindex
- offset
)
2026 r
= dns_packet_read_type_windows(p
, &rr
->nsec
.types
, offset
+ rdlength
- p
->rindex
, NULL
);
2028 /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
2029 * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records
2030 * without the NSEC bit set. */
2034 case DNS_TYPE_NSEC3
: {
2037 r
= dns_packet_read_uint8(p
, &rr
->nsec3
.algorithm
, NULL
);
2041 r
= dns_packet_read_uint8(p
, &rr
->nsec3
.flags
, NULL
);
2045 r
= dns_packet_read_uint16(p
, &rr
->nsec3
.iterations
, NULL
);
2049 /* this may be zero */
2050 r
= dns_packet_read_uint8(p
, &size
, NULL
);
2054 r
= dns_packet_read_memdup(p
, size
, &rr
->nsec3
.salt
, &rr
->nsec3
.salt_size
, NULL
);
2058 r
= dns_packet_read_uint8(p
, &size
, NULL
);
2065 r
= dns_packet_read_memdup(p
, size
,
2066 &rr
->nsec3
.next_hashed_name
, &rr
->nsec3
.next_hashed_name_size
,
2071 if (rdlength
< p
->rindex
- offset
)
2074 r
= dns_packet_read_type_windows(p
, &rr
->nsec3
.types
, offset
+ rdlength
- p
->rindex
, NULL
);
2076 /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
2082 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.cert_usage
, NULL
);
2086 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.selector
, NULL
);
2090 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.matching_type
, NULL
);
2097 r
= dns_packet_read_memdup(p
, rdlength
- 3,
2098 &rr
->tlsa
.data
, &rr
->tlsa
.data_size
,
2101 if (rr
->tlsa
.data_size
<= 0)
2102 /* the accepted size depends on the algorithm, but for now
2103 just ensure that the value is greater than zero */
2109 r
= dns_packet_read_uint8(p
, &rr
->caa
.flags
, NULL
);
2113 r
= dns_packet_read_string(p
, &rr
->caa
.tag
, NULL
);
2117 if (rdlength
< p
->rindex
- offset
)
2120 r
= dns_packet_read_memdup(p
,
2121 rdlength
+ offset
- p
->rindex
,
2122 &rr
->caa
.value
, &rr
->caa
.value_size
, NULL
);
2126 case DNS_TYPE_OPT
: /* we only care about the header of OPT for now. */
2127 case DNS_TYPE_OPENPGPKEY
:
2130 r
= dns_packet_read_memdup(p
, rdlength
, &rr
->generic
.data
, &rr
->generic
.data_size
, NULL
);
2136 if (p
->rindex
- offset
!= rdlength
)
2140 *ret
= TAKE_PTR(rr
);
2141 if (ret_cache_flush
)
2142 *ret_cache_flush
= cache_flush
;
2144 *ret_start
= rewinder
.saved_rindex
;
2146 CANCEL_REWINDER(rewinder
);
2150 static bool opt_is_good(DnsResourceRecord
*rr
, bool *rfc6975
) {
2152 bool found_dau_dhu_n3u
= false;
2155 /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in
2159 assert(rr
->key
->type
== DNS_TYPE_OPT
);
2161 /* Check that the version is 0 */
2162 if (((rr
->ttl
>> 16) & UINT32_C(0xFF)) != 0) {
2164 return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */
2168 l
= rr
->opt
.data_size
;
2170 uint16_t option_code
, option_length
;
2172 /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */
2176 option_code
= unaligned_read_be16(p
);
2177 option_length
= unaligned_read_be16(p
+ 2);
2179 if (l
< option_length
+ 4U)
2182 /* RFC 6975 DAU, DHU or N3U fields found. */
2183 if (IN_SET(option_code
, 5, 6, 7))
2184 found_dau_dhu_n3u
= true;
2186 p
+= option_length
+ 4U;
2187 l
-= option_length
+ 4U;
2190 *rfc6975
= found_dau_dhu_n3u
;
2194 static int dns_packet_extract_question(DnsPacket
*p
, DnsQuestion
**ret_question
) {
2195 _cleanup_(dns_question_unrefp
) DnsQuestion
*question
= NULL
;
2199 n
= DNS_PACKET_QDCOUNT(p
);
2201 question
= dns_question_new(n
);
2205 _cleanup_set_free_ Set
*keys
= NULL
; /* references to keys are kept by Question */
2207 keys
= set_new(&dns_resource_key_hash_ops
);
2211 r
= set_reserve(keys
, n
* 2); /* Higher multipliers give slightly higher efficiency through
2212 * hash collisions, but the gains quickly drop off after 2. */
2216 for (unsigned i
= 0; i
< n
; i
++) {
2217 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
2220 r
= dns_packet_read_key(p
, &key
, &qu
, NULL
);
2224 if (!dns_type_is_valid_query(key
->type
))
2227 r
= set_put(keys
, key
);
2231 /* Already in the Question, let's skip */
2234 r
= dns_question_add_raw(question
, key
, qu
? DNS_QUESTION_WANTS_UNICAST_REPLY
: 0);
2240 *ret_question
= TAKE_PTR(question
);
2245 static int dns_packet_extract_answer(DnsPacket
*p
, DnsAnswer
**ret_answer
) {
2246 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
2248 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*previous
= NULL
;
2249 bool bad_opt
= false;
2252 n
= DNS_PACKET_RRCOUNT(p
);
2256 answer
= dns_answer_new(n
);
2260 for (unsigned i
= 0; i
< n
; i
++) {
2261 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
2262 bool cache_flush
= false;
2265 if (p
->rindex
== p
->size
&& p
->opt
) {
2266 /* If we reached the end of the packet already, but there are still more RRs
2267 * declared, then that's a corrupt packet. Let's accept the packet anyway, since it's
2268 * apparently a common bug in routers. Let's however suppress OPT support in this
2269 * case, so that we force the rest of the logic into lowest DNS baseline support. Or
2270 * to say this differently: if the DNS server doesn't even get the RR counts right,
2271 * it's highly unlikely it gets EDNS right. */
2272 log_debug("More resource records declared in packet than included, suppressing OPT.");
2277 r
= dns_packet_read_rr(p
, &rr
, &cache_flush
, &start
);
2281 /* Try to reduce memory usage a bit */
2283 dns_resource_key_reduce(&rr
->key
, &previous
->key
);
2285 if (rr
->key
->type
== DNS_TYPE_OPT
) {
2288 if (p
->opt
|| bad_opt
) {
2289 /* Multiple OPT RRs? if so, let's ignore all, because there's
2290 * something wrong with the server, and if one is valid we wouldn't
2291 * know which one. */
2292 log_debug("Multiple OPT RRs detected, ignoring all.");
2297 if (!dns_name_is_root(dns_resource_key_name(rr
->key
))) {
2298 /* If the OPT RR is not owned by the root domain, then it is bad,
2299 * let's ignore it. */
2300 log_debug("OPT RR is not owned by root domain, ignoring.");
2305 if (i
< DNS_PACKET_ANCOUNT(p
) + DNS_PACKET_NSCOUNT(p
)) {
2306 /* OPT RR is in the wrong section? Some Belkin routers do this. This
2307 * is a hint the EDNS implementation is borked, like the Belkin one
2308 * is, hence ignore it. */
2309 log_debug("OPT RR in wrong section, ignoring.");
2314 if (!opt_is_good(rr
, &has_rfc6975
)) {
2315 log_debug("Malformed OPT RR, ignoring.");
2320 if (DNS_PACKET_QR(p
)) {
2321 /* Additional checks for responses */
2323 if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr
))
2324 /* If this is a reply and we don't know the EDNS version
2325 * then something is weird... */
2326 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2327 "EDNS version newer that our request, bad server.");
2330 /* If the OPT RR contains RFC6975 algorithm data, then this
2331 * is indication that the server just copied the OPT it got
2332 * from us (which contained that data) back into the reply.
2333 * If so, then it doesn't properly support EDNS, as RFC6975
2334 * makes it very clear that the algorithm data should only
2335 * be contained in questions, never in replies. Crappy
2336 * Belkin routers copy the OPT data for example, hence let's
2337 * detect this so that we downgrade early. */
2338 log_debug("OPT RR contains RFC6975 data, ignoring.");
2344 p
->opt
= dns_resource_record_ref(rr
);
2345 p
->opt_start
= start
;
2346 assert(p
->rindex
>= start
);
2347 p
->opt_size
= p
->rindex
- start
;
2349 DnsAnswerFlags flags
= 0;
2351 if (p
->protocol
== DNS_PROTOCOL_MDNS
&& !cache_flush
)
2352 flags
|= DNS_ANSWER_SHARED_OWNER
;
2354 /* According to RFC 4795, section 2.9. only the RRs from the Answer section shall be
2355 * cached. Hence mark only those RRs as cacheable by default, but not the ones from
2356 * the Additional or Authority sections.
2357 * This restriction does not apply to mDNS records (RFC 6762). */
2358 if (i
< DNS_PACKET_ANCOUNT(p
))
2359 flags
|= DNS_ANSWER_CACHEABLE
|DNS_ANSWER_SECTION_ANSWER
;
2360 else if (i
< DNS_PACKET_ANCOUNT(p
) + DNS_PACKET_NSCOUNT(p
))
2361 flags
|= DNS_ANSWER_SECTION_AUTHORITY
;
2363 flags
|= DNS_ANSWER_SECTION_ADDITIONAL
;
2364 if (p
->protocol
== DNS_PROTOCOL_MDNS
)
2365 flags
|= DNS_ANSWER_CACHEABLE
;
2368 r
= dns_answer_add(answer
, rr
, p
->ifindex
, flags
, NULL
);
2373 /* Remember this RR, so that we can potentially merge its ->key object with the
2374 * next RR. Note that we only do this if we actually decided to keep the RR around.
2376 DNS_RR_REPLACE(previous
, dns_resource_record_ref(rr
));
2380 p
->opt
= dns_resource_record_unref(p
->opt
);
2381 p
->opt_start
= p
->opt_size
= SIZE_MAX
;
2384 *ret_answer
= TAKE_PTR(answer
);
2389 int dns_packet_extract(DnsPacket
*p
) {
2395 _cleanup_(dns_question_unrefp
) DnsQuestion
*question
= NULL
;
2396 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
2397 _unused_
_cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
2400 dns_packet_rewind(p
, DNS_PACKET_HEADER_SIZE
);
2402 r
= dns_packet_extract_question(p
, &question
);
2406 r
= dns_packet_extract_answer(p
, &answer
);
2410 if (p
->rindex
< p
->size
) {
2411 log_debug("Trailing garbage in packet, suppressing OPT.");
2412 p
->opt
= dns_resource_record_unref(p
->opt
);
2413 p
->opt_start
= p
->opt_size
= SIZE_MAX
;
2416 p
->question
= TAKE_PTR(question
);
2417 p
->answer
= TAKE_PTR(answer
);
2418 p
->extracted
= true;
2420 /* no CANCEL, always rewind */
2424 int dns_packet_is_reply_for(DnsPacket
*p
, const DnsResourceKey
*key
) {
2430 /* Checks if the specified packet is a reply for the specified
2431 * key and the specified key is the only one in the question
2434 if (DNS_PACKET_QR(p
) != 1)
2437 /* Let's unpack the packet, if that hasn't happened yet. */
2438 r
= dns_packet_extract(p
);
2445 if (p
->question
->n_keys
!= 1)
2448 return dns_resource_key_equal(dns_question_first_key(p
->question
), key
);
2451 int dns_packet_patch_max_udp_size(DnsPacket
*p
, uint16_t max_udp_size
) {
2453 assert(max_udp_size
>= DNS_PACKET_UNICAST_SIZE_MAX
);
2455 if (p
->opt_start
== SIZE_MAX
) /* No OPT section, nothing to patch */
2458 assert(p
->opt_size
!= SIZE_MAX
);
2459 assert(p
->opt_size
>= 5);
2461 unaligned_write_be16(DNS_PACKET_DATA(p
) + p
->opt_start
+ 3, max_udp_size
);
2465 static int patch_rr(DnsPacket
*p
, usec_t age
) {
2466 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
2469 uint16_t type
, rdlength
;
2472 /* Patches the RR at the current rindex, subtracts the specified time from the TTL */
2474 r
= dns_packet_read_name(p
, NULL
, true, NULL
);
2478 r
= dns_packet_read_uint16(p
, &type
, NULL
);
2482 r
= dns_packet_read_uint16(p
, NULL
, NULL
);
2486 r
= dns_packet_read_uint32(p
, &ttl
, &ttl_index
);
2490 if (type
!= DNS_TYPE_OPT
) { /* The TTL of the OPT field is not actually a TTL, skip it */
2491 ttl
= LESS_BY(ttl
* USEC_PER_SEC
, age
) / USEC_PER_SEC
;
2492 unaligned_write_be32(DNS_PACKET_DATA(p
) + ttl_index
, ttl
);
2495 r
= dns_packet_read_uint16(p
, &rdlength
, NULL
);
2499 r
= dns_packet_read(p
, rdlength
, NULL
, NULL
);
2503 CANCEL_REWINDER(rewinder
);
2507 int dns_packet_patch_ttls(DnsPacket
*p
, usec_t timestamp
) {
2509 assert(timestamp_is_set(timestamp
));
2511 /* Adjusts all TTLs in the packet by subtracting the time difference between now and the specified timestamp */
2513 _unused_
_cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= REWINDER_INIT(p
);
2518 k
= now(CLOCK_BOOTTIME
);
2519 assert(k
>= timestamp
);
2522 dns_packet_rewind(p
, DNS_PACKET_HEADER_SIZE
);
2524 n
= DNS_PACKET_QDCOUNT(p
);
2525 for (unsigned i
= 0; i
< n
; i
++) {
2526 r
= dns_packet_read_key(p
, NULL
, NULL
, NULL
);
2531 n
= DNS_PACKET_RRCOUNT(p
);
2532 for (unsigned i
= 0; i
< n
; i
++) {
2534 /* DNS servers suck, hence the RR count is in many servers off. If we reached the end
2535 * prematurely, accept that, exit early */
2536 if (p
->rindex
== p
->size
)
2547 static void dns_packet_hash_func(const DnsPacket
*s
, struct siphash
*state
) {
2550 siphash24_compress(&s
->size
, sizeof(s
->size
), state
);
2551 siphash24_compress(DNS_PACKET_DATA((DnsPacket
*) s
), s
->size
, state
);
2554 static int dns_packet_compare_func(const DnsPacket
*x
, const DnsPacket
*y
) {
2557 r
= CMP(x
->size
, y
->size
);
2561 return memcmp(DNS_PACKET_DATA((DnsPacket
*) x
), DNS_PACKET_DATA((DnsPacket
*) y
), x
->size
);
2564 DEFINE_HASH_OPS(dns_packet_hash_ops
, DnsPacket
, dns_packet_hash_func
, dns_packet_compare_func
);
2566 bool dns_packet_equal(const DnsPacket
*a
, const DnsPacket
*b
) {
2567 return dns_packet_compare_func(a
, b
) == 0;
2570 int dns_packet_has_nsid_request(DnsPacket
*p
) {
2571 bool has_nsid
= false;
2580 d
= p
->opt
->opt
.data
;
2581 l
= p
->opt
->opt
.data_size
;
2584 uint16_t code
, length
;
2587 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2588 "EDNS0 variable part has invalid size.");
2590 code
= unaligned_read_be16(d
);
2591 length
= unaligned_read_be16(d
+ 2);
2593 if (l
< 4U + length
)
2594 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2595 "Truncated option in EDNS0 variable part.");
2599 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2600 "Duplicate NSID option in EDNS0 variable part.");
2603 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG
),
2604 "Non-empty NSID option in DNS request.");
2616 size_t dns_packet_size_unfragmented(DnsPacket
*p
) {
2619 if (p
->fragsize
== 0) /* Wasn't fragmented */
2622 /* The fragment size (p->fragsize) covers the whole (fragmented) IP packet, while the regular packet
2623 * size (p->size) only covers the DNS part. Thus, subtract the UDP header from the largest fragment
2624 * size, in order to determine which size of DNS packet would have gone through without
2627 return LESS_BY(p
->fragsize
, udp_header_size(p
->family
));
2630 static const char* const dns_rcode_table
[_DNS_RCODE_MAX_DEFINED
] = {
2631 [DNS_RCODE_SUCCESS
] = "SUCCESS",
2632 [DNS_RCODE_FORMERR
] = "FORMERR",
2633 [DNS_RCODE_SERVFAIL
] = "SERVFAIL",
2634 [DNS_RCODE_NXDOMAIN
] = "NXDOMAIN",
2635 [DNS_RCODE_NOTIMP
] = "NOTIMP",
2636 [DNS_RCODE_REFUSED
] = "REFUSED",
2637 [DNS_RCODE_YXDOMAIN
] = "YXDOMAIN",
2638 [DNS_RCODE_YXRRSET
] = "YRRSET",
2639 [DNS_RCODE_NXRRSET
] = "NXRRSET",
2640 [DNS_RCODE_NOTAUTH
] = "NOTAUTH",
2641 [DNS_RCODE_NOTZONE
] = "NOTZONE",
2642 [DNS_RCODE_BADVERS
] = "BADVERS",
2643 [DNS_RCODE_BADKEY
] = "BADKEY",
2644 [DNS_RCODE_BADTIME
] = "BADTIME",
2645 [DNS_RCODE_BADMODE
] = "BADMODE",
2646 [DNS_RCODE_BADNAME
] = "BADNAME",
2647 [DNS_RCODE_BADALG
] = "BADALG",
2648 [DNS_RCODE_BADTRUNC
] = "BADTRUNC",
2649 [DNS_RCODE_BADCOOKIE
] = "BADCOOKIE",
2651 DEFINE_STRING_TABLE_LOOKUP(dns_rcode
, int);
2653 const char *format_dns_rcode(int i
, char buf
[static DECIMAL_STR_MAX(int)]) {
2654 const char *p
= dns_rcode_to_string(i
);
2658 return snprintf_ok(buf
, DECIMAL_STR_MAX(int), "%i", i
);
2661 static const char* const dns_protocol_table
[_DNS_PROTOCOL_MAX
] = {
2662 [DNS_PROTOCOL_DNS
] = "dns",
2663 [DNS_PROTOCOL_MDNS
] = "mdns",
2664 [DNS_PROTOCOL_LLMNR
] = "llmnr",
2666 DEFINE_STRING_TABLE_LOOKUP(dns_protocol
, DnsProtocol
);