1 /* SPDX-License-Identifier: LGPL-2.1+ */
7 #include "alloc-util.h"
8 #include "dns-domain.h"
9 #include "resolved-dns-packet.h"
10 #include "string-table.h"
12 #include "unaligned.h"
16 #define EDNS0_OPT_DO (1<<15)
18 assert_cc(DNS_PACKET_SIZE_START
> DNS_PACKET_HEADER_SIZE
)
20 typedef struct DnsPacketRewinder
{
25 static void rewind_dns_packet(DnsPacketRewinder
*rewinder
) {
27 dns_packet_rewind(rewinder
->packet
, rewinder
->saved_rindex
);
30 #define INIT_REWINDER(rewinder, p) do { rewinder.packet = p; rewinder.saved_rindex = p->rindex; } while (0)
31 #define CANCEL_REWINDER(rewinder) do { rewinder.packet = NULL; } while (0)
36 size_t min_alloc_dsize
,
43 assert(max_size
>= DNS_PACKET_HEADER_SIZE
);
45 if (max_size
> DNS_PACKET_SIZE_MAX
)
46 max_size
= DNS_PACKET_SIZE_MAX
;
48 /* The caller may not check what is going to be truly allocated, so do not allow to
49 * allocate a DNS packet bigger than DNS_PACKET_SIZE_MAX.
51 if (min_alloc_dsize
> DNS_PACKET_SIZE_MAX
)
52 return log_error_errno(SYNTHETIC_ERRNO(EFBIG
),
53 "Requested packet data size too big: %zu",
56 /* When dns_packet_new() is called with min_alloc_dsize == 0, allocate more than the
57 * absolute minimum (which is the dns packet header size), to avoid
58 * resizing immediately again after appending the first data to the packet.
60 if (min_alloc_dsize
< DNS_PACKET_HEADER_SIZE
)
61 a
= DNS_PACKET_SIZE_START
;
65 /* round up to next page size */
66 a
= PAGE_ALIGN(ALIGN(sizeof(DnsPacket
)) + a
) - ALIGN(sizeof(DnsPacket
));
68 /* make sure we never allocate more than useful */
72 p
= malloc0(ALIGN(sizeof(DnsPacket
)) + a
);
76 p
->size
= p
->rindex
= DNS_PACKET_HEADER_SIZE
;
78 p
->max_size
= max_size
;
79 p
->protocol
= protocol
;
80 p
->opt_start
= p
->opt_size
= (size_t) -1;
88 void dns_packet_set_flags(DnsPacket
*p
, bool dnssec_checking_disabled
, bool truncated
) {
94 h
= DNS_PACKET_HEADER(p
);
97 case DNS_PROTOCOL_LLMNR
:
100 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
111 case DNS_PROTOCOL_MDNS
:
112 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
116 0 /* rd (ask for recursion) */,
126 h
->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
130 1 /* rd (ask for recursion) */,
133 dnssec_checking_disabled
/* cd */,
138 int dns_packet_new_query(DnsPacket
**ret
, DnsProtocol protocol
, size_t min_alloc_dsize
, bool dnssec_checking_disabled
) {
144 r
= dns_packet_new(&p
, protocol
, min_alloc_dsize
, DNS_PACKET_SIZE_MAX
);
148 /* Always set the TC bit to 0 initially.
149 * If there are multiple packets later, we'll update the bit shortly before sending.
151 dns_packet_set_flags(p
, dnssec_checking_disabled
, false);
157 DnsPacket
*dns_packet_ref(DnsPacket
*p
) {
162 assert(!p
->on_stack
);
164 assert(p
->n_ref
> 0);
169 static void dns_packet_free(DnsPacket
*p
) {
174 dns_question_unref(p
->question
);
175 dns_answer_unref(p
->answer
);
176 dns_resource_record_unref(p
->opt
);
178 while ((s
= hashmap_steal_first_key(p
->names
)))
180 hashmap_free(p
->names
);
188 DnsPacket
*dns_packet_unref(DnsPacket
*p
) {
192 assert(p
->n_ref
> 0);
194 dns_packet_unref(p
->more
);
204 int dns_packet_validate(DnsPacket
*p
) {
207 if (p
->size
< DNS_PACKET_HEADER_SIZE
)
210 if (p
->size
> DNS_PACKET_SIZE_MAX
)
216 int dns_packet_validate_reply(DnsPacket
*p
) {
221 r
= dns_packet_validate(p
);
225 if (DNS_PACKET_QR(p
) != 1)
228 if (DNS_PACKET_OPCODE(p
) != 0)
231 switch (p
->protocol
) {
233 case DNS_PROTOCOL_LLMNR
:
234 /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
235 if (DNS_PACKET_QDCOUNT(p
) != 1)
240 case DNS_PROTOCOL_MDNS
:
241 /* RFC 6762, Section 18 */
242 if (DNS_PACKET_RCODE(p
) != 0)
254 int dns_packet_validate_query(DnsPacket
*p
) {
259 r
= dns_packet_validate(p
);
263 if (DNS_PACKET_QR(p
) != 0)
266 if (DNS_PACKET_OPCODE(p
) != 0)
269 if (DNS_PACKET_TC(p
))
272 switch (p
->protocol
) {
274 case DNS_PROTOCOL_LLMNR
:
275 case DNS_PROTOCOL_DNS
:
276 /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
277 if (DNS_PACKET_QDCOUNT(p
) != 1)
280 /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
281 if (DNS_PACKET_ANCOUNT(p
) > 0)
284 /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
285 if (DNS_PACKET_NSCOUNT(p
) > 0)
290 case DNS_PROTOCOL_MDNS
:
291 /* RFC 6762, Section 18 */
292 if (DNS_PACKET_AA(p
) != 0 ||
293 DNS_PACKET_RD(p
) != 0 ||
294 DNS_PACKET_RA(p
) != 0 ||
295 DNS_PACKET_AD(p
) != 0 ||
296 DNS_PACKET_CD(p
) != 0 ||
297 DNS_PACKET_RCODE(p
) != 0)
309 static int dns_packet_extend(DnsPacket
*p
, size_t add
, void **ret
, size_t *start
) {
312 if (p
->size
+ add
> p
->allocated
) {
315 a
= PAGE_ALIGN((p
->size
+ add
) * 2);
317 ms
= dns_packet_size_max(p
);
321 if (p
->size
+ add
> a
)
327 d
= realloc(p
->_data
, a
);
333 p
->_data
= malloc(a
);
337 memcpy(p
->_data
, (uint8_t*) p
+ ALIGN(sizeof(DnsPacket
)), p
->size
);
338 memzero((uint8_t*) p
->_data
+ p
->size
, a
- p
->size
);
348 *ret
= (uint8_t*) DNS_PACKET_DATA(p
) + p
->size
;
354 void dns_packet_truncate(DnsPacket
*p
, size_t sz
) {
364 HASHMAP_FOREACH_KEY(n
, s
, p
->names
, i
) {
366 if (PTR_TO_SIZE(n
) < sz
)
369 hashmap_remove(p
->names
, s
);
376 int dns_packet_append_blob(DnsPacket
*p
, const void *d
, size_t l
, size_t *start
) {
382 r
= dns_packet_extend(p
, l
, &q
, start
);
386 memcpy_safe(q
, d
, l
);
390 int dns_packet_append_uint8(DnsPacket
*p
, uint8_t v
, size_t *start
) {
396 r
= dns_packet_extend(p
, sizeof(uint8_t), &d
, start
);
400 ((uint8_t*) d
)[0] = v
;
405 int dns_packet_append_uint16(DnsPacket
*p
, uint16_t v
, size_t *start
) {
411 r
= dns_packet_extend(p
, sizeof(uint16_t), &d
, start
);
415 unaligned_write_be16(d
, v
);
420 int dns_packet_append_uint32(DnsPacket
*p
, uint32_t v
, size_t *start
) {
426 r
= dns_packet_extend(p
, sizeof(uint32_t), &d
, start
);
430 unaligned_write_be32(d
, v
);
435 int dns_packet_append_string(DnsPacket
*p
, const char *s
, size_t *start
) {
439 return dns_packet_append_raw_string(p
, s
, strlen(s
), start
);
442 int dns_packet_append_raw_string(DnsPacket
*p
, const void *s
, size_t size
, size_t *start
) {
447 assert(s
|| size
== 0);
452 r
= dns_packet_extend(p
, 1 + size
, &d
, start
);
456 ((uint8_t*) d
)[0] = (uint8_t) size
;
458 memcpy_safe(((uint8_t*) d
) + 1, s
, size
);
463 int dns_packet_append_label(DnsPacket
*p
, const char *d
, size_t l
, bool canonical_candidate
, size_t *start
) {
467 /* Append a label to a packet. Optionally, does this in DNSSEC
468 * canonical form, if this label is marked as a candidate for
469 * it, and the canonical form logic is enabled for the
475 if (l
> DNS_LABEL_MAX
)
478 r
= dns_packet_extend(p
, 1 + l
, (void**) &w
, start
);
482 *(w
++) = (uint8_t) l
;
484 if (p
->canonical_form
&& canonical_candidate
) {
487 /* Generate in canonical form, as defined by DNSSEC
488 * RFC 4034, Section 6.2, i.e. all lower-case. */
490 for (i
= 0; i
< l
; i
++)
491 w
[i
] = (uint8_t) ascii_tolower(d
[i
]);
493 /* Otherwise, just copy the string unaltered. This is
494 * essential for DNS-SD, where the casing of labels
495 * matters and needs to be retained. */
501 int dns_packet_append_name(
504 bool allow_compression
,
505 bool canonical_candidate
,
514 if (p
->refuse_compression
)
515 allow_compression
= false;
517 saved_size
= p
->size
;
519 while (!dns_name_is_root(name
)) {
520 const char *z
= name
;
521 char label
[DNS_LABEL_MAX
];
524 if (allow_compression
)
525 n
= PTR_TO_SIZE(hashmap_get(p
->names
, name
));
530 r
= dns_packet_append_uint16(p
, 0xC000 | n
, NULL
);
538 r
= dns_label_unescape(&name
, label
, sizeof(label
));
542 r
= dns_packet_append_label(p
, label
, r
, canonical_candidate
, &n
);
546 if (allow_compression
) {
547 _cleanup_free_
char *s
= NULL
;
555 r
= hashmap_ensure_allocated(&p
->names
, &dns_name_hash_ops
);
559 r
= hashmap_put(p
->names
, s
, SIZE_TO_PTR(n
));
567 r
= dns_packet_append_uint8(p
, 0, NULL
);
578 dns_packet_truncate(p
, saved_size
);
582 int dns_packet_append_key(DnsPacket
*p
, const DnsResourceKey
*k
, const DnsAnswerFlags flags
, size_t *start
) {
590 saved_size
= p
->size
;
592 r
= dns_packet_append_name(p
, dns_resource_key_name(k
), true, true, NULL
);
596 r
= dns_packet_append_uint16(p
, k
->type
, NULL
);
600 class = flags
& DNS_ANSWER_CACHE_FLUSH
? k
->class | MDNS_RR_CACHE_FLUSH
: k
->class;
601 r
= dns_packet_append_uint16(p
, class, NULL
);
611 dns_packet_truncate(p
, saved_size
);
615 static int dns_packet_append_type_window(DnsPacket
*p
, uint8_t window
, uint8_t length
, const uint8_t *types
, size_t *start
) {
623 saved_size
= p
->size
;
625 r
= dns_packet_append_uint8(p
, window
, NULL
);
629 r
= dns_packet_append_uint8(p
, length
, NULL
);
633 r
= dns_packet_append_blob(p
, types
, length
, NULL
);
642 dns_packet_truncate(p
, saved_size
);
646 static int dns_packet_append_types(DnsPacket
*p
, Bitmap
*types
, size_t *start
) {
650 uint8_t bitmaps
[32] = {};
657 saved_size
= p
->size
;
659 BITMAP_FOREACH(n
, types
, i
) {
662 if ((n
>> 8) != window
&& bitmaps
[entry
/ 8] != 0) {
663 r
= dns_packet_append_type_window(p
, window
, entry
/ 8 + 1, bitmaps
, NULL
);
673 bitmaps
[entry
/ 8] |= 1 << (7 - (entry
% 8));
676 if (bitmaps
[entry
/ 8] != 0) {
677 r
= dns_packet_append_type_window(p
, window
, entry
/ 8 + 1, bitmaps
, NULL
);
687 dns_packet_truncate(p
, saved_size
);
691 /* Append the OPT pseudo-RR described in RFC6891 */
692 int dns_packet_append_opt(DnsPacket
*p
, uint16_t max_udp_size
, bool edns0_do
, int rcode
, size_t *start
) {
697 /* we must never advertise supported packet size smaller than the legacy max */
698 assert(max_udp_size
>= DNS_PACKET_UNICAST_SIZE_MAX
);
700 assert(rcode
<= _DNS_RCODE_MAX
);
702 if (p
->opt_start
!= (size_t) -1)
705 assert(p
->opt_size
== (size_t) -1);
707 saved_size
= p
->size
;
710 r
= dns_packet_append_uint8(p
, 0, NULL
);
715 r
= dns_packet_append_uint16(p
, DNS_TYPE_OPT
, NULL
);
719 /* class: maximum udp packet that can be received */
720 r
= dns_packet_append_uint16(p
, max_udp_size
, NULL
);
724 /* extended RCODE and VERSION */
725 r
= dns_packet_append_uint16(p
, ((uint16_t) rcode
& 0x0FF0) << 4, NULL
);
729 /* flags: DNSSEC OK (DO), see RFC3225 */
730 r
= dns_packet_append_uint16(p
, edns0_do
? EDNS0_OPT_DO
: 0, NULL
);
735 if (edns0_do
&& !DNS_PACKET_QR(p
)) {
736 /* If DO is on and this is not a reply, also append RFC6975 Algorithm data */
738 static const uint8_t rfc6975
[] = {
740 0, 5, /* OPTION_CODE: DAU */
741 #if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600
742 0, 7, /* LIST_LENGTH */
744 0, 6, /* LIST_LENGTH */
746 DNSSEC_ALGORITHM_RSASHA1
,
747 DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1
,
748 DNSSEC_ALGORITHM_RSASHA256
,
749 DNSSEC_ALGORITHM_RSASHA512
,
750 DNSSEC_ALGORITHM_ECDSAP256SHA256
,
751 DNSSEC_ALGORITHM_ECDSAP384SHA384
,
752 #if HAVE_GCRYPT && GCRYPT_VERSION_NUMBER >= 0x010600
753 DNSSEC_ALGORITHM_ED25519
,
756 0, 6, /* OPTION_CODE: DHU */
757 0, 3, /* LIST_LENGTH */
759 DNSSEC_DIGEST_SHA256
,
760 DNSSEC_DIGEST_SHA384
,
762 0, 7, /* OPTION_CODE: N3U */
763 0, 1, /* LIST_LENGTH */
764 NSEC3_ALGORITHM_SHA1
,
767 r
= dns_packet_append_uint16(p
, sizeof(rfc6975
), NULL
);
771 r
= dns_packet_append_blob(p
, rfc6975
, sizeof(rfc6975
), NULL
);
773 r
= dns_packet_append_uint16(p
, 0, NULL
);
777 DNS_PACKET_HEADER(p
)->arcount
= htobe16(DNS_PACKET_ARCOUNT(p
) + 1);
779 p
->opt_start
= saved_size
;
780 p
->opt_size
= p
->size
- saved_size
;
788 dns_packet_truncate(p
, saved_size
);
792 int dns_packet_truncate_opt(DnsPacket
*p
) {
795 if (p
->opt_start
== (size_t) -1) {
796 assert(p
->opt_size
== (size_t) -1);
800 assert(p
->opt_size
!= (size_t) -1);
801 assert(DNS_PACKET_ARCOUNT(p
) > 0);
803 if (p
->opt_start
+ p
->opt_size
!= p
->size
)
806 dns_packet_truncate(p
, p
->opt_start
);
807 DNS_PACKET_HEADER(p
)->arcount
= htobe16(DNS_PACKET_ARCOUNT(p
) - 1);
808 p
->opt_start
= p
->opt_size
= (size_t) -1;
813 int dns_packet_append_rr(DnsPacket
*p
, const DnsResourceRecord
*rr
, const DnsAnswerFlags flags
, size_t *start
, size_t *rdata_start
) {
815 size_t saved_size
, rdlength_offset
, end
, rdlength
, rds
;
822 saved_size
= p
->size
;
824 r
= dns_packet_append_key(p
, rr
->key
, flags
, NULL
);
828 ttl
= flags
& DNS_ANSWER_GOODBYE
? 0 : rr
->ttl
;
829 r
= dns_packet_append_uint32(p
, ttl
, NULL
);
833 /* Initially we write 0 here */
834 r
= dns_packet_append_uint16(p
, 0, &rdlength_offset
);
838 rds
= p
->size
- saved_size
;
840 switch (rr
->unparseable
? _DNS_TYPE_INVALID
: rr
->key
->type
) {
843 r
= dns_packet_append_uint16(p
, rr
->srv
.priority
, NULL
);
847 r
= dns_packet_append_uint16(p
, rr
->srv
.weight
, NULL
);
851 r
= dns_packet_append_uint16(p
, rr
->srv
.port
, NULL
);
855 /* RFC 2782 states "Unless and until permitted by future standards
856 * action, name compression is not to be used for this field." */
857 r
= dns_packet_append_name(p
, rr
->srv
.name
, false, false, NULL
);
864 r
= dns_packet_append_name(p
, rr
->ptr
.name
, true, false, NULL
);
868 r
= dns_packet_append_string(p
, rr
->hinfo
.cpu
, NULL
);
872 r
= dns_packet_append_string(p
, rr
->hinfo
.os
, NULL
);
875 case DNS_TYPE_SPF
: /* exactly the same as TXT */
878 if (!rr
->txt
.items
) {
879 /* RFC 6763, section 6.1 suggests to generate
880 * single empty string for an empty array. */
882 r
= dns_packet_append_raw_string(p
, NULL
, 0, NULL
);
888 LIST_FOREACH(items
, i
, rr
->txt
.items
) {
889 r
= dns_packet_append_raw_string(p
, i
->data
, i
->length
, NULL
);
899 r
= dns_packet_append_blob(p
, &rr
->a
.in_addr
, sizeof(struct in_addr
), NULL
);
903 r
= dns_packet_append_blob(p
, &rr
->aaaa
.in6_addr
, sizeof(struct in6_addr
), NULL
);
907 r
= dns_packet_append_name(p
, rr
->soa
.mname
, true, false, NULL
);
911 r
= dns_packet_append_name(p
, rr
->soa
.rname
, true, false, NULL
);
915 r
= dns_packet_append_uint32(p
, rr
->soa
.serial
, NULL
);
919 r
= dns_packet_append_uint32(p
, rr
->soa
.refresh
, NULL
);
923 r
= dns_packet_append_uint32(p
, rr
->soa
.retry
, NULL
);
927 r
= dns_packet_append_uint32(p
, rr
->soa
.expire
, NULL
);
931 r
= dns_packet_append_uint32(p
, rr
->soa
.minimum
, NULL
);
935 r
= dns_packet_append_uint16(p
, rr
->mx
.priority
, NULL
);
939 r
= dns_packet_append_name(p
, rr
->mx
.exchange
, true, false, NULL
);
943 r
= dns_packet_append_uint8(p
, rr
->loc
.version
, NULL
);
947 r
= dns_packet_append_uint8(p
, rr
->loc
.size
, NULL
);
951 r
= dns_packet_append_uint8(p
, rr
->loc
.horiz_pre
, NULL
);
955 r
= dns_packet_append_uint8(p
, rr
->loc
.vert_pre
, NULL
);
959 r
= dns_packet_append_uint32(p
, rr
->loc
.latitude
, NULL
);
963 r
= dns_packet_append_uint32(p
, rr
->loc
.longitude
, NULL
);
967 r
= dns_packet_append_uint32(p
, rr
->loc
.altitude
, NULL
);
971 r
= dns_packet_append_uint16(p
, rr
->ds
.key_tag
, NULL
);
975 r
= dns_packet_append_uint8(p
, rr
->ds
.algorithm
, NULL
);
979 r
= dns_packet_append_uint8(p
, rr
->ds
.digest_type
, NULL
);
983 r
= dns_packet_append_blob(p
, rr
->ds
.digest
, rr
->ds
.digest_size
, NULL
);
987 r
= dns_packet_append_uint8(p
, rr
->sshfp
.algorithm
, NULL
);
991 r
= dns_packet_append_uint8(p
, rr
->sshfp
.fptype
, NULL
);
995 r
= dns_packet_append_blob(p
, rr
->sshfp
.fingerprint
, rr
->sshfp
.fingerprint_size
, NULL
);
998 case DNS_TYPE_DNSKEY
:
999 r
= dns_packet_append_uint16(p
, rr
->dnskey
.flags
, NULL
);
1003 r
= dns_packet_append_uint8(p
, rr
->dnskey
.protocol
, NULL
);
1007 r
= dns_packet_append_uint8(p
, rr
->dnskey
.algorithm
, NULL
);
1011 r
= dns_packet_append_blob(p
, rr
->dnskey
.key
, rr
->dnskey
.key_size
, NULL
);
1014 case DNS_TYPE_RRSIG
:
1015 r
= dns_packet_append_uint16(p
, rr
->rrsig
.type_covered
, NULL
);
1019 r
= dns_packet_append_uint8(p
, rr
->rrsig
.algorithm
, NULL
);
1023 r
= dns_packet_append_uint8(p
, rr
->rrsig
.labels
, NULL
);
1027 r
= dns_packet_append_uint32(p
, rr
->rrsig
.original_ttl
, NULL
);
1031 r
= dns_packet_append_uint32(p
, rr
->rrsig
.expiration
, NULL
);
1035 r
= dns_packet_append_uint32(p
, rr
->rrsig
.inception
, NULL
);
1039 r
= dns_packet_append_uint16(p
, rr
->rrsig
.key_tag
, NULL
);
1043 r
= dns_packet_append_name(p
, rr
->rrsig
.signer
, false, true, NULL
);
1047 r
= dns_packet_append_blob(p
, rr
->rrsig
.signature
, rr
->rrsig
.signature_size
, NULL
);
1051 r
= dns_packet_append_name(p
, rr
->nsec
.next_domain_name
, false, false, NULL
);
1055 r
= dns_packet_append_types(p
, rr
->nsec
.types
, NULL
);
1061 case DNS_TYPE_NSEC3
:
1062 r
= dns_packet_append_uint8(p
, rr
->nsec3
.algorithm
, NULL
);
1066 r
= dns_packet_append_uint8(p
, rr
->nsec3
.flags
, NULL
);
1070 r
= dns_packet_append_uint16(p
, rr
->nsec3
.iterations
, NULL
);
1074 r
= dns_packet_append_uint8(p
, rr
->nsec3
.salt_size
, NULL
);
1078 r
= dns_packet_append_blob(p
, rr
->nsec3
.salt
, rr
->nsec3
.salt_size
, NULL
);
1082 r
= dns_packet_append_uint8(p
, rr
->nsec3
.next_hashed_name_size
, NULL
);
1086 r
= dns_packet_append_blob(p
, rr
->nsec3
.next_hashed_name
, rr
->nsec3
.next_hashed_name_size
, NULL
);
1090 r
= dns_packet_append_types(p
, rr
->nsec3
.types
, NULL
);
1097 r
= dns_packet_append_uint8(p
, rr
->tlsa
.cert_usage
, NULL
);
1101 r
= dns_packet_append_uint8(p
, rr
->tlsa
.selector
, NULL
);
1105 r
= dns_packet_append_uint8(p
, rr
->tlsa
.matching_type
, NULL
);
1109 r
= dns_packet_append_blob(p
, rr
->tlsa
.data
, rr
->tlsa
.data_size
, NULL
);
1113 r
= dns_packet_append_uint8(p
, rr
->caa
.flags
, NULL
);
1117 r
= dns_packet_append_string(p
, rr
->caa
.tag
, NULL
);
1121 r
= dns_packet_append_blob(p
, rr
->caa
.value
, rr
->caa
.value_size
, NULL
);
1125 case DNS_TYPE_OPENPGPKEY
:
1126 case _DNS_TYPE_INVALID
: /* unparseable */
1129 r
= dns_packet_append_blob(p
, rr
->generic
.data
, rr
->generic
.data_size
, NULL
);
1135 /* Let's calculate the actual data size and update the field */
1136 rdlength
= p
->size
- rdlength_offset
- sizeof(uint16_t);
1137 if (rdlength
> 0xFFFF) {
1143 p
->size
= rdlength_offset
;
1144 r
= dns_packet_append_uint16(p
, rdlength
, NULL
);
1150 *start
= saved_size
;
1158 dns_packet_truncate(p
, saved_size
);
1162 int dns_packet_append_question(DnsPacket
*p
, DnsQuestion
*q
) {
1163 DnsResourceKey
*key
;
1168 DNS_QUESTION_FOREACH(key
, q
) {
1169 r
= dns_packet_append_key(p
, key
, 0, NULL
);
1177 int dns_packet_append_answer(DnsPacket
*p
, DnsAnswer
*a
) {
1178 DnsResourceRecord
*rr
;
1179 DnsAnswerFlags flags
;
1184 DNS_ANSWER_FOREACH_FLAGS(rr
, flags
, a
) {
1185 r
= dns_packet_append_rr(p
, rr
, flags
, NULL
, NULL
);
1193 int dns_packet_read(DnsPacket
*p
, size_t sz
, const void **ret
, size_t *start
) {
1196 if (p
->rindex
+ sz
> p
->size
)
1200 *ret
= (uint8_t*) DNS_PACKET_DATA(p
) + p
->rindex
;
1209 void dns_packet_rewind(DnsPacket
*p
, size_t idx
) {
1211 assert(idx
<= p
->size
);
1212 assert(idx
>= DNS_PACKET_HEADER_SIZE
);
1217 int dns_packet_read_blob(DnsPacket
*p
, void *d
, size_t sz
, size_t *start
) {
1224 r
= dns_packet_read(p
, sz
, &q
, start
);
1232 static int dns_packet_read_memdup(
1233 DnsPacket
*p
, size_t size
,
1234 void **ret
, size_t *ret_size
,
1235 size_t *ret_start
) {
1244 r
= dns_packet_read(p
, size
, &src
, &start
);
1253 copy
= memdup(src
, size
);
1268 int dns_packet_read_uint8(DnsPacket
*p
, uint8_t *ret
, size_t *start
) {
1274 r
= dns_packet_read(p
, sizeof(uint8_t), &d
, start
);
1278 *ret
= ((uint8_t*) d
)[0];
1282 int dns_packet_read_uint16(DnsPacket
*p
, uint16_t *ret
, size_t *start
) {
1288 r
= dns_packet_read(p
, sizeof(uint16_t), &d
, start
);
1292 *ret
= unaligned_read_be16(d
);
1297 int dns_packet_read_uint32(DnsPacket
*p
, uint32_t *ret
, size_t *start
) {
1303 r
= dns_packet_read(p
, sizeof(uint32_t), &d
, start
);
1307 *ret
= unaligned_read_be32(d
);
1312 int dns_packet_read_string(DnsPacket
*p
, char **ret
, size_t *start
) {
1313 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1320 INIT_REWINDER(rewinder
, p
);
1322 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1326 r
= dns_packet_read(p
, c
, &d
, NULL
);
1330 if (memchr(d
, 0, c
))
1337 if (!utf8_is_valid(t
)) {
1345 *start
= rewinder
.saved_rindex
;
1346 CANCEL_REWINDER(rewinder
);
1351 int dns_packet_read_raw_string(DnsPacket
*p
, const void **ret
, size_t *size
, size_t *start
) {
1352 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1357 INIT_REWINDER(rewinder
, p
);
1359 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1363 r
= dns_packet_read(p
, c
, ret
, NULL
);
1370 *start
= rewinder
.saved_rindex
;
1371 CANCEL_REWINDER(rewinder
);
1376 int dns_packet_read_name(
1379 bool allow_compression
,
1382 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1383 size_t after_rindex
= 0, jump_barrier
;
1384 _cleanup_free_
char *ret
= NULL
;
1385 size_t n
= 0, allocated
= 0;
1391 INIT_REWINDER(rewinder
, p
);
1392 jump_barrier
= p
->rindex
;
1394 if (p
->refuse_compression
)
1395 allow_compression
= false;
1400 r
= dns_packet_read_uint8(p
, &c
, NULL
);
1411 r
= dns_packet_read(p
, c
, (const void**) &label
, NULL
);
1415 if (!GREEDY_REALLOC(ret
, allocated
, n
+ !first
+ DNS_LABEL_ESCAPED_MAX
))
1423 r
= dns_label_escape(label
, c
, ret
+ n
, DNS_LABEL_ESCAPED_MAX
);
1429 } else if (allow_compression
&& (c
& 0xc0) == 0xc0) {
1433 r
= dns_packet_read_uint8(p
, &d
, NULL
);
1437 ptr
= (uint16_t) (c
& ~0xc0) << 8 | (uint16_t) d
;
1438 if (ptr
< DNS_PACKET_HEADER_SIZE
|| ptr
>= jump_barrier
)
1441 if (after_rindex
== 0)
1442 after_rindex
= p
->rindex
;
1444 /* Jumps are limited to a "prior occurrence" (RFC-1035 4.1.4) */
1451 if (!GREEDY_REALLOC(ret
, allocated
, n
+ 1))
1456 if (after_rindex
!= 0)
1457 p
->rindex
= after_rindex
;
1459 *_ret
= TAKE_PTR(ret
);
1462 *start
= rewinder
.saved_rindex
;
1463 CANCEL_REWINDER(rewinder
);
1468 static int dns_packet_read_type_window(DnsPacket
*p
, Bitmap
**types
, size_t *start
) {
1471 const uint8_t *bitmap
;
1475 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1480 INIT_REWINDER(rewinder
, p
);
1482 r
= bitmap_ensure_allocated(types
);
1486 r
= dns_packet_read_uint8(p
, &window
, NULL
);
1490 r
= dns_packet_read_uint8(p
, &length
, NULL
);
1494 if (length
== 0 || length
> 32)
1497 r
= dns_packet_read(p
, length
, (const void **)&bitmap
, NULL
);
1501 for (i
= 0; i
< length
; i
++) {
1502 uint8_t bitmask
= 1 << 7;
1512 for (; bitmask
; bit
++, bitmask
>>= 1)
1513 if (bitmap
[i
] & bitmask
) {
1516 n
= (uint16_t) window
<< 8 | (uint16_t) bit
;
1518 /* Ignore pseudo-types. see RFC4034 section 4.1.2 */
1519 if (dns_type_is_pseudo(n
))
1522 r
= bitmap_set(*types
, n
);
1532 *start
= rewinder
.saved_rindex
;
1533 CANCEL_REWINDER(rewinder
);
1538 static int dns_packet_read_type_windows(DnsPacket
*p
, Bitmap
**types
, size_t size
, size_t *start
) {
1539 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1542 INIT_REWINDER(rewinder
, p
);
1544 while (p
->rindex
< rewinder
.saved_rindex
+ size
) {
1545 r
= dns_packet_read_type_window(p
, types
, NULL
);
1549 /* don't read past end of current RR */
1550 if (p
->rindex
> rewinder
.saved_rindex
+ size
)
1554 if (p
->rindex
!= rewinder
.saved_rindex
+ size
)
1558 *start
= rewinder
.saved_rindex
;
1559 CANCEL_REWINDER(rewinder
);
1564 int dns_packet_read_key(DnsPacket
*p
, DnsResourceKey
**ret
, bool *ret_cache_flush
, size_t *start
) {
1565 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1566 _cleanup_free_
char *name
= NULL
;
1567 bool cache_flush
= false;
1568 uint16_t class, type
;
1569 DnsResourceKey
*key
;
1574 INIT_REWINDER(rewinder
, p
);
1576 r
= dns_packet_read_name(p
, &name
, true, NULL
);
1580 r
= dns_packet_read_uint16(p
, &type
, NULL
);
1584 r
= dns_packet_read_uint16(p
, &class, NULL
);
1588 if (p
->protocol
== DNS_PROTOCOL_MDNS
) {
1589 /* See RFC6762, Section 10.2 */
1591 if (type
!= DNS_TYPE_OPT
&& (class & MDNS_RR_CACHE_FLUSH
)) {
1592 class &= ~MDNS_RR_CACHE_FLUSH
;
1597 key
= dns_resource_key_new_consume(class, type
, name
);
1604 if (ret_cache_flush
)
1605 *ret_cache_flush
= cache_flush
;
1607 *start
= rewinder
.saved_rindex
;
1608 CANCEL_REWINDER(rewinder
);
1613 static bool loc_size_ok(uint8_t size
) {
1614 uint8_t m
= size
>> 4, e
= size
& 0xF;
1616 return m
<= 9 && e
<= 9 && (m
> 0 || e
== 0);
1619 int dns_packet_read_rr(DnsPacket
*p
, DnsResourceRecord
**ret
, bool *ret_cache_flush
, size_t *start
) {
1620 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
1621 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
1622 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
;
1631 INIT_REWINDER(rewinder
, p
);
1633 r
= dns_packet_read_key(p
, &key
, &cache_flush
, NULL
);
1637 if (!dns_class_is_valid_rr(key
->class) || !dns_type_is_valid_rr(key
->type
))
1640 rr
= dns_resource_record_new(key
);
1644 r
= dns_packet_read_uint32(p
, &rr
->ttl
, NULL
);
1648 /* RFC 2181, Section 8, suggests to
1649 * treat a TTL with the MSB set as a zero TTL. */
1650 if (rr
->ttl
& UINT32_C(0x80000000))
1653 r
= dns_packet_read_uint16(p
, &rdlength
, NULL
);
1657 if (p
->rindex
+ rdlength
> p
->size
)
1662 switch (rr
->key
->type
) {
1665 r
= dns_packet_read_uint16(p
, &rr
->srv
.priority
, NULL
);
1668 r
= dns_packet_read_uint16(p
, &rr
->srv
.weight
, NULL
);
1671 r
= dns_packet_read_uint16(p
, &rr
->srv
.port
, NULL
);
1674 r
= dns_packet_read_name(p
, &rr
->srv
.name
, true, NULL
);
1679 case DNS_TYPE_CNAME
:
1680 case DNS_TYPE_DNAME
:
1681 r
= dns_packet_read_name(p
, &rr
->ptr
.name
, true, NULL
);
1684 case DNS_TYPE_HINFO
:
1685 r
= dns_packet_read_string(p
, &rr
->hinfo
.cpu
, NULL
);
1689 r
= dns_packet_read_string(p
, &rr
->hinfo
.os
, NULL
);
1692 case DNS_TYPE_SPF
: /* exactly the same as TXT */
1694 if (rdlength
<= 0) {
1695 r
= dns_txt_item_new_empty(&rr
->txt
.items
);
1699 DnsTxtItem
*last
= NULL
;
1701 while (p
->rindex
< offset
+ rdlength
) {
1706 r
= dns_packet_read_raw_string(p
, &data
, &sz
, NULL
);
1710 i
= malloc0(offsetof(DnsTxtItem
, data
) + sz
+ 1); /* extra NUL byte at the end */
1714 memcpy(i
->data
, data
, sz
);
1717 LIST_INSERT_AFTER(items
, rr
->txt
.items
, last
, i
);
1726 r
= dns_packet_read_blob(p
, &rr
->a
.in_addr
, sizeof(struct in_addr
), NULL
);
1730 r
= dns_packet_read_blob(p
, &rr
->aaaa
.in6_addr
, sizeof(struct in6_addr
), NULL
);
1734 r
= dns_packet_read_name(p
, &rr
->soa
.mname
, true, NULL
);
1738 r
= dns_packet_read_name(p
, &rr
->soa
.rname
, true, NULL
);
1742 r
= dns_packet_read_uint32(p
, &rr
->soa
.serial
, NULL
);
1746 r
= dns_packet_read_uint32(p
, &rr
->soa
.refresh
, NULL
);
1750 r
= dns_packet_read_uint32(p
, &rr
->soa
.retry
, NULL
);
1754 r
= dns_packet_read_uint32(p
, &rr
->soa
.expire
, NULL
);
1758 r
= dns_packet_read_uint32(p
, &rr
->soa
.minimum
, NULL
);
1762 r
= dns_packet_read_uint16(p
, &rr
->mx
.priority
, NULL
);
1766 r
= dns_packet_read_name(p
, &rr
->mx
.exchange
, true, NULL
);
1769 case DNS_TYPE_LOC
: {
1773 r
= dns_packet_read_uint8(p
, &t
, &pos
);
1778 rr
->loc
.version
= t
;
1780 r
= dns_packet_read_uint8(p
, &rr
->loc
.size
, NULL
);
1784 if (!loc_size_ok(rr
->loc
.size
))
1787 r
= dns_packet_read_uint8(p
, &rr
->loc
.horiz_pre
, NULL
);
1791 if (!loc_size_ok(rr
->loc
.horiz_pre
))
1794 r
= dns_packet_read_uint8(p
, &rr
->loc
.vert_pre
, NULL
);
1798 if (!loc_size_ok(rr
->loc
.vert_pre
))
1801 r
= dns_packet_read_uint32(p
, &rr
->loc
.latitude
, NULL
);
1805 r
= dns_packet_read_uint32(p
, &rr
->loc
.longitude
, NULL
);
1809 r
= dns_packet_read_uint32(p
, &rr
->loc
.altitude
, NULL
);
1815 dns_packet_rewind(p
, pos
);
1816 rr
->unparseable
= true;
1822 r
= dns_packet_read_uint16(p
, &rr
->ds
.key_tag
, NULL
);
1826 r
= dns_packet_read_uint8(p
, &rr
->ds
.algorithm
, NULL
);
1830 r
= dns_packet_read_uint8(p
, &rr
->ds
.digest_type
, NULL
);
1837 r
= dns_packet_read_memdup(p
, rdlength
- 4,
1838 &rr
->ds
.digest
, &rr
->ds
.digest_size
,
1843 if (rr
->ds
.digest_size
<= 0)
1844 /* the accepted size depends on the algorithm, but for now
1845 just ensure that the value is greater than zero */
1850 case DNS_TYPE_SSHFP
:
1851 r
= dns_packet_read_uint8(p
, &rr
->sshfp
.algorithm
, NULL
);
1855 r
= dns_packet_read_uint8(p
, &rr
->sshfp
.fptype
, NULL
);
1862 r
= dns_packet_read_memdup(p
, rdlength
- 2,
1863 &rr
->sshfp
.fingerprint
, &rr
->sshfp
.fingerprint_size
,
1866 if (rr
->sshfp
.fingerprint_size
<= 0)
1867 /* the accepted size depends on the algorithm, but for now
1868 just ensure that the value is greater than zero */
1873 case DNS_TYPE_DNSKEY
:
1874 r
= dns_packet_read_uint16(p
, &rr
->dnskey
.flags
, NULL
);
1878 r
= dns_packet_read_uint8(p
, &rr
->dnskey
.protocol
, NULL
);
1882 r
= dns_packet_read_uint8(p
, &rr
->dnskey
.algorithm
, NULL
);
1889 r
= dns_packet_read_memdup(p
, rdlength
- 4,
1890 &rr
->dnskey
.key
, &rr
->dnskey
.key_size
,
1893 if (rr
->dnskey
.key_size
<= 0)
1894 /* the accepted size depends on the algorithm, but for now
1895 just ensure that the value is greater than zero */
1900 case DNS_TYPE_RRSIG
:
1901 r
= dns_packet_read_uint16(p
, &rr
->rrsig
.type_covered
, NULL
);
1905 r
= dns_packet_read_uint8(p
, &rr
->rrsig
.algorithm
, NULL
);
1909 r
= dns_packet_read_uint8(p
, &rr
->rrsig
.labels
, NULL
);
1913 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.original_ttl
, NULL
);
1917 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.expiration
, NULL
);
1921 r
= dns_packet_read_uint32(p
, &rr
->rrsig
.inception
, NULL
);
1925 r
= dns_packet_read_uint16(p
, &rr
->rrsig
.key_tag
, NULL
);
1929 r
= dns_packet_read_name(p
, &rr
->rrsig
.signer
, false, NULL
);
1933 if (rdlength
+ offset
< p
->rindex
)
1936 r
= dns_packet_read_memdup(p
, offset
+ rdlength
- p
->rindex
,
1937 &rr
->rrsig
.signature
, &rr
->rrsig
.signature_size
,
1940 if (rr
->rrsig
.signature_size
<= 0)
1941 /* the accepted size depends on the algorithm, but for now
1942 just ensure that the value is greater than zero */
1947 case DNS_TYPE_NSEC
: {
1950 * RFC6762, section 18.14 explictly states mDNS should use name compression.
1951 * This contradicts RFC3845, section 2.1.1
1954 bool allow_compressed
= p
->protocol
== DNS_PROTOCOL_MDNS
;
1956 r
= dns_packet_read_name(p
, &rr
->nsec
.next_domain_name
, allow_compressed
, NULL
);
1960 r
= dns_packet_read_type_windows(p
, &rr
->nsec
.types
, offset
+ rdlength
- p
->rindex
, NULL
);
1962 /* We accept empty NSEC bitmaps. The bit indicating the presence of the NSEC record itself
1963 * is redundant and in e.g., RFC4956 this fact is used to define a use for NSEC records
1964 * without the NSEC bit set. */
1968 case DNS_TYPE_NSEC3
: {
1971 r
= dns_packet_read_uint8(p
, &rr
->nsec3
.algorithm
, NULL
);
1975 r
= dns_packet_read_uint8(p
, &rr
->nsec3
.flags
, NULL
);
1979 r
= dns_packet_read_uint16(p
, &rr
->nsec3
.iterations
, NULL
);
1983 /* this may be zero */
1984 r
= dns_packet_read_uint8(p
, &size
, NULL
);
1988 r
= dns_packet_read_memdup(p
, size
, &rr
->nsec3
.salt
, &rr
->nsec3
.salt_size
, NULL
);
1992 r
= dns_packet_read_uint8(p
, &size
, NULL
);
1999 r
= dns_packet_read_memdup(p
, size
,
2000 &rr
->nsec3
.next_hashed_name
, &rr
->nsec3
.next_hashed_name_size
,
2005 r
= dns_packet_read_type_windows(p
, &rr
->nsec3
.types
, offset
+ rdlength
- p
->rindex
, NULL
);
2007 /* empty non-terminals can have NSEC3 records, so empty bitmaps are allowed */
2013 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.cert_usage
, NULL
);
2017 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.selector
, NULL
);
2021 r
= dns_packet_read_uint8(p
, &rr
->tlsa
.matching_type
, NULL
);
2028 r
= dns_packet_read_memdup(p
, rdlength
- 3,
2029 &rr
->tlsa
.data
, &rr
->tlsa
.data_size
,
2032 if (rr
->tlsa
.data_size
<= 0)
2033 /* the accepted size depends on the algorithm, but for now
2034 just ensure that the value is greater than zero */
2040 r
= dns_packet_read_uint8(p
, &rr
->caa
.flags
, NULL
);
2044 r
= dns_packet_read_string(p
, &rr
->caa
.tag
, NULL
);
2048 if (rdlength
+ offset
< p
->rindex
)
2051 r
= dns_packet_read_memdup(p
,
2052 rdlength
+ offset
- p
->rindex
,
2053 &rr
->caa
.value
, &rr
->caa
.value_size
, NULL
);
2057 case DNS_TYPE_OPT
: /* we only care about the header of OPT for now. */
2058 case DNS_TYPE_OPENPGPKEY
:
2061 r
= dns_packet_read_memdup(p
, rdlength
, &rr
->generic
.data
, &rr
->generic
.data_size
, NULL
);
2067 if (p
->rindex
!= offset
+ rdlength
)
2070 *ret
= TAKE_PTR(rr
);
2072 if (ret_cache_flush
)
2073 *ret_cache_flush
= cache_flush
;
2075 *start
= rewinder
.saved_rindex
;
2076 CANCEL_REWINDER(rewinder
);
2081 static bool opt_is_good(DnsResourceRecord
*rr
, bool *rfc6975
) {
2083 bool found_dau_dhu_n3u
= false;
2086 /* Checks whether the specified OPT RR is well-formed and whether it contains RFC6975 data (which is not OK in
2090 assert(rr
->key
->type
== DNS_TYPE_OPT
);
2092 /* Check that the version is 0 */
2093 if (((rr
->ttl
>> 16) & UINT32_C(0xFF)) != 0) {
2095 return true; /* if it's not version 0, it's OK, but we will ignore the OPT field contents */
2099 l
= rr
->opt
.data_size
;
2101 uint16_t option_code
, option_length
;
2103 /* At least four bytes for OPTION-CODE and OPTION-LENGTH are required */
2107 option_code
= unaligned_read_be16(p
);
2108 option_length
= unaligned_read_be16(p
+ 2);
2110 if (l
< option_length
+ 4U)
2113 /* RFC 6975 DAU, DHU or N3U fields found. */
2114 if (IN_SET(option_code
, 5, 6, 7))
2115 found_dau_dhu_n3u
= true;
2117 p
+= option_length
+ 4U;
2118 l
-= option_length
+ 4U;
2121 *rfc6975
= found_dau_dhu_n3u
;
2125 static int dns_packet_extract_question(DnsPacket
*p
, DnsQuestion
**ret_question
) {
2126 _cleanup_(dns_question_unrefp
) DnsQuestion
*question
= NULL
;
2130 n
= DNS_PACKET_QDCOUNT(p
);
2132 question
= dns_question_new(n
);
2136 for (i
= 0; i
< n
; i
++) {
2137 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
2140 r
= dns_packet_read_key(p
, &key
, &cache_flush
, NULL
);
2147 if (!dns_type_is_valid_query(key
->type
))
2150 r
= dns_question_add(question
, key
);
2156 *ret_question
= TAKE_PTR(question
);
2161 static int dns_packet_extract_answer(DnsPacket
*p
, DnsAnswer
**ret_answer
) {
2162 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
2164 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*previous
= NULL
;
2165 bool bad_opt
= false;
2168 n
= DNS_PACKET_RRCOUNT(p
);
2172 answer
= dns_answer_new(n
);
2176 for (i
= 0; i
< n
; i
++) {
2177 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
2178 bool cache_flush
= false;
2180 r
= dns_packet_read_rr(p
, &rr
, &cache_flush
, NULL
);
2184 /* Try to reduce memory usage a bit */
2186 dns_resource_key_reduce(&rr
->key
, &previous
->key
);
2188 if (rr
->key
->type
== DNS_TYPE_OPT
) {
2191 if (p
->opt
|| bad_opt
) {
2192 /* Multiple OPT RRs? if so, let's ignore all, because there's
2193 * something wrong with the server, and if one is valid we wouldn't
2194 * know which one. */
2195 log_debug("Multiple OPT RRs detected, ignoring all.");
2200 if (!dns_name_is_root(dns_resource_key_name(rr
->key
))) {
2201 /* If the OPT RR is not owned by the root domain, then it is bad,
2202 * let's ignore it. */
2203 log_debug("OPT RR is not owned by root domain, ignoring.");
2208 if (i
< DNS_PACKET_ANCOUNT(p
) + DNS_PACKET_NSCOUNT(p
)) {
2209 /* OPT RR is in the wrong section? Some Belkin routers do this. This
2210 * is a hint the EDNS implementation is borked, like the Belkin one
2211 * is, hence ignore it. */
2212 log_debug("OPT RR in wrong section, ignoring.");
2217 if (!opt_is_good(rr
, &has_rfc6975
)) {
2218 log_debug("Malformed OPT RR, ignoring.");
2223 if (DNS_PACKET_QR(p
)) {
2224 /* Additional checks for responses */
2226 if (!DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(rr
)) {
2227 /* If this is a reply and we don't know the EDNS version
2228 * then something is weird... */
2229 log_debug("EDNS version newer that our request, bad server.");
2234 /* If the OPT RR contains RFC6975 algorithm data, then this
2235 * is indication that the server just copied the OPT it got
2236 * from us (which contained that data) back into the reply.
2237 * If so, then it doesn't properly support EDNS, as RFC6975
2238 * makes it very clear that the algorithm data should only
2239 * be contained in questions, never in replies. Crappy
2240 * Belkin routers copy the OPT data for example, hence let's
2241 * detect this so that we downgrade early. */
2242 log_debug("OPT RR contained RFC6975 data, ignoring.");
2248 p
->opt
= dns_resource_record_ref(rr
);
2250 /* According to RFC 4795, section 2.9. only the RRs from the Answer section
2251 * shall be cached. Hence mark only those RRs as cacheable by default, but
2252 * not the ones from the Additional or Authority sections. */
2253 DnsAnswerFlags flags
=
2254 (i
< DNS_PACKET_ANCOUNT(p
) ? DNS_ANSWER_CACHEABLE
: 0) |
2255 (p
->protocol
== DNS_PROTOCOL_MDNS
&& !cache_flush
? DNS_ANSWER_SHARED_OWNER
: 0);
2257 r
= dns_answer_add(answer
, rr
, p
->ifindex
, flags
);
2262 /* Remember this RR, so that we potentically can merge it's ->key object with the
2263 * next RR. Note that we only do this if we actually decided to keep the RR around.
2265 dns_resource_record_unref(previous
);
2266 previous
= dns_resource_record_ref(rr
);
2270 p
->opt
= dns_resource_record_unref(p
->opt
);
2272 *ret_answer
= TAKE_PTR(answer
);
2277 int dns_packet_extract(DnsPacket
*p
) {
2278 _cleanup_(dns_question_unrefp
) DnsQuestion
*question
= NULL
;
2279 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
2280 _cleanup_(rewind_dns_packet
) DnsPacketRewinder rewinder
= {};
2286 INIT_REWINDER(rewinder
, p
);
2287 dns_packet_rewind(p
, DNS_PACKET_HEADER_SIZE
);
2289 r
= dns_packet_extract_question(p
, &question
);
2293 r
= dns_packet_extract_answer(p
, &answer
);
2297 p
->question
= TAKE_PTR(question
);
2298 p
->answer
= TAKE_PTR(answer
);
2300 p
->extracted
= true;
2302 /* no CANCEL, always rewind */
2306 int dns_packet_is_reply_for(DnsPacket
*p
, const DnsResourceKey
*key
) {
2312 /* Checks if the specified packet is a reply for the specified
2313 * key and the specified key is the only one in the question
2316 if (DNS_PACKET_QR(p
) != 1)
2319 /* Let's unpack the packet, if that hasn't happened yet. */
2320 r
= dns_packet_extract(p
);
2327 if (p
->question
->n_keys
!= 1)
2330 return dns_resource_key_equal(p
->question
->keys
[0], key
);
2333 static void dns_packet_hash_func(const DnsPacket
*s
, struct siphash
*state
) {
2336 siphash24_compress(&s
->size
, sizeof(s
->size
), state
);
2337 siphash24_compress(DNS_PACKET_DATA((DnsPacket
*) s
), s
->size
, state
);
2340 static int dns_packet_compare_func(const DnsPacket
*x
, const DnsPacket
*y
) {
2343 r
= CMP(x
->size
, y
->size
);
2347 return memcmp(DNS_PACKET_DATA((DnsPacket
*) x
), DNS_PACKET_DATA((DnsPacket
*) y
), x
->size
);
2350 DEFINE_HASH_OPS(dns_packet_hash_ops
, DnsPacket
, dns_packet_hash_func
, dns_packet_compare_func
);
2352 static const char* const dns_rcode_table
[_DNS_RCODE_MAX_DEFINED
] = {
2353 [DNS_RCODE_SUCCESS
] = "SUCCESS",
2354 [DNS_RCODE_FORMERR
] = "FORMERR",
2355 [DNS_RCODE_SERVFAIL
] = "SERVFAIL",
2356 [DNS_RCODE_NXDOMAIN
] = "NXDOMAIN",
2357 [DNS_RCODE_NOTIMP
] = "NOTIMP",
2358 [DNS_RCODE_REFUSED
] = "REFUSED",
2359 [DNS_RCODE_YXDOMAIN
] = "YXDOMAIN",
2360 [DNS_RCODE_YXRRSET
] = "YRRSET",
2361 [DNS_RCODE_NXRRSET
] = "NXRRSET",
2362 [DNS_RCODE_NOTAUTH
] = "NOTAUTH",
2363 [DNS_RCODE_NOTZONE
] = "NOTZONE",
2364 [DNS_RCODE_BADVERS
] = "BADVERS",
2365 [DNS_RCODE_BADKEY
] = "BADKEY",
2366 [DNS_RCODE_BADTIME
] = "BADTIME",
2367 [DNS_RCODE_BADMODE
] = "BADMODE",
2368 [DNS_RCODE_BADNAME
] = "BADNAME",
2369 [DNS_RCODE_BADALG
] = "BADALG",
2370 [DNS_RCODE_BADTRUNC
] = "BADTRUNC",
2371 [DNS_RCODE_BADCOOKIE
] = "BADCOOKIE",
2373 DEFINE_STRING_TABLE_LOOKUP(dns_rcode
, int);
2375 static const char* const dns_protocol_table
[_DNS_PROTOCOL_MAX
] = {
2376 [DNS_PROTOCOL_DNS
] = "dns",
2377 [DNS_PROTOCOL_MDNS
] = "mdns",
2378 [DNS_PROTOCOL_LLMNR
] = "llmnr",
2380 DEFINE_STRING_TABLE_LOOKUP(dns_protocol
, DnsProtocol
);