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53e1b683 | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
74b2466e LP |
2 | #pragma once |
3 | ||
4 | /*** | |
5 | This file is part of systemd. | |
6 | ||
7 | Copyright 2014 Lennart Poettering | |
8 | ||
9 | systemd is free software; you can redistribute it and/or modify it | |
10 | under the terms of the GNU Lesser General Public License as published by | |
11 | the Free Software Foundation; either version 2.1 of the License, or | |
12 | (at your option) any later version. | |
13 | ||
14 | systemd is distributed in the hope that it will be useful, but | |
15 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
17 | Lesser General Public License for more details. | |
18 | ||
19 | You should have received a copy of the GNU Lesser General Public License | |
20 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
21 | ***/ | |
22 | ||
a0166609 | 23 | #include <netinet/ip.h> |
71d35b6b | 24 | #include <netinet/udp.h> |
74b2466e | 25 | |
74b2466e | 26 | #include "hashmap.h" |
7e8e0422 | 27 | #include "in-addr-util.h" |
71d35b6b TA |
28 | #include "macro.h" |
29 | #include "sparse-endian.h" | |
7e8e0422 LP |
30 | |
31 | typedef struct DnsPacketHeader DnsPacketHeader; | |
32 | typedef struct DnsPacket DnsPacket; | |
33 | ||
51323288 | 34 | #include "resolved-def.h" |
71d35b6b TA |
35 | #include "resolved-dns-answer.h" |
36 | #include "resolved-dns-question.h" | |
37 | #include "resolved-dns-rr.h" | |
74b2466e | 38 | |
1716f6dc LP |
39 | typedef enum DnsProtocol { |
40 | DNS_PROTOCOL_DNS, | |
41 | DNS_PROTOCOL_MDNS, | |
42 | DNS_PROTOCOL_LLMNR, | |
43 | _DNS_PROTOCOL_MAX, | |
44 | _DNS_PROTOCOL_INVALID = -1 | |
45 | } DnsProtocol; | |
46 | ||
74b2466e LP |
47 | struct DnsPacketHeader { |
48 | uint16_t id; | |
49 | be16_t flags; | |
50 | be16_t qdcount; | |
51 | be16_t ancount; | |
52 | be16_t nscount; | |
53 | be16_t arcount; | |
54 | }; | |
55 | ||
56 | #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader) | |
a0166609 | 57 | #define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr)) |
c73ce96b LP |
58 | |
59 | /* The various DNS protocols deviate in how large a packet can grow, | |
86d06089 ZJS |
60 | * but the TCP transport has a 16bit size field, hence that appears to |
61 | * be the absolute maximum. */ | |
64a21fda | 62 | #define DNS_PACKET_SIZE_MAX 0xFFFFu |
e1c95994 | 63 | |
86d06089 ZJS |
64 | /* The default size to use for allocation when we don't know how large |
65 | * the packet will turn out to be. */ | |
66 | #define DNS_PACKET_SIZE_START 512u | |
67 | ||
e1c95994 | 68 | /* RFC 1035 say 512 is the maximum, for classic unicast DNS */ |
64a21fda | 69 | #define DNS_PACKET_UNICAST_SIZE_MAX 512u |
e1c95994 | 70 | |
d74fb368 | 71 | /* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */ |
64a21fda | 72 | #define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096u |
d74fb368 | 73 | |
74b2466e LP |
74 | struct DnsPacket { |
75 | int n_ref; | |
1716f6dc | 76 | DnsProtocol protocol; |
51027656 | 77 | size_t size, allocated, rindex, max_size; |
faa133f3 | 78 | void *_data; /* don't access directly, use DNS_PACKET_DATA()! */ |
74b2466e | 79 | Hashmap *names; /* For name compression */ |
519ef046 | 80 | size_t opt_start, opt_size; |
faa133f3 LP |
81 | |
82 | /* Parsed data */ | |
83 | DnsQuestion *question; | |
84 | DnsAnswer *answer; | |
d75acfb0 | 85 | DnsResourceRecord *opt; |
1716f6dc | 86 | |
dc61b7e4 | 87 | /* Packet reception metadata */ |
1716f6dc | 88 | int ifindex; |
623a4c97 | 89 | int family, ipproto; |
1716f6dc | 90 | union in_addr_union sender, destination; |
623a4c97 | 91 | uint16_t sender_port, destination_port; |
0dd25fb9 | 92 | uint32_t ttl; |
a4076574 | 93 | |
9c491563 DM |
94 | /* For support of truncated packets */ |
95 | DnsPacket *more; | |
96 | ||
a8812dd7 LP |
97 | bool on_stack:1; |
98 | bool extracted:1; | |
99 | bool refuse_compression:1; | |
100 | bool canonical_form:1; | |
74b2466e LP |
101 | }; |
102 | ||
103 | static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) { | |
104 | if (_unlikely_(!p)) | |
105 | return NULL; | |
106 | ||
faa133f3 LP |
107 | if (p->_data) |
108 | return p->_data; | |
74b2466e LP |
109 | |
110 | return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket)); | |
111 | } | |
112 | ||
113 | #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p)) | |
3cb10d3a LP |
114 | #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id |
115 | #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1) | |
116 | #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15) | |
8b757a38 | 117 | #define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1) |
ad867662 | 118 | #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1) |
8b757a38 DM |
119 | #define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1) |
120 | #define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1) | |
121 | #define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1) | |
122 | #define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1) | |
f3abbe25 | 123 | |
b30bf55d LP |
124 | #define DNS_PACKET_FLAG_TC (UINT16_C(1) << 9) |
125 | ||
f3abbe25 LP |
126 | static inline uint16_t DNS_PACKET_RCODE(DnsPacket *p) { |
127 | uint16_t rcode; | |
128 | ||
129 | if (p->opt) | |
130 | rcode = (uint16_t) (p->opt->ttl >> 24); | |
131 | else | |
132 | rcode = 0; | |
133 | ||
b30bf55d LP |
134 | return rcode | (be16toh(DNS_PACKET_HEADER(p)->flags) & 0xF); |
135 | } | |
136 | ||
137 | static inline uint16_t DNS_PACKET_PAYLOAD_SIZE_MAX(DnsPacket *p) { | |
138 | ||
139 | /* Returns the advertised maximum datagram size for replies, or the DNS default if there's nothing defined. */ | |
140 | ||
141 | if (p->opt) | |
142 | return MAX(DNS_PACKET_UNICAST_SIZE_MAX, p->opt->key->class); | |
143 | ||
144 | return DNS_PACKET_UNICAST_SIZE_MAX; | |
145 | } | |
146 | ||
147 | static inline bool DNS_PACKET_DO(DnsPacket *p) { | |
148 | if (!p->opt) | |
149 | return false; | |
150 | ||
151 | return !!(p->opt->ttl & (1U << 15)); | |
152 | } | |
153 | ||
154 | static inline bool DNS_PACKET_VERSION_SUPPORTED(DnsPacket *p) { | |
155 | /* Returns true if this packet is in a version we support. Which means either non-EDNS or EDNS(0), but not EDNS | |
156 | * of any newer versions */ | |
157 | ||
158 | if (!p->opt) | |
159 | return true; | |
160 | ||
161 | return DNS_RESOURCE_RECORD_OPT_VERSION_SUPPORTED(p->opt); | |
f3abbe25 | 162 | } |
8b757a38 DM |
163 | |
164 | /* LLMNR defines some bits differently */ | |
165 | #define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p) | |
166 | #define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p) | |
167 | ||
3cb10d3a LP |
168 | #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount) |
169 | #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount) | |
170 | #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount) | |
171 | #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount) | |
172 | ||
173 | #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \ | |
f0258e47 LP |
174 | (((uint16_t) !!(qr) << 15) | \ |
175 | ((uint16_t) ((opcode) & 15) << 11) | \ | |
176 | ((uint16_t) !!(aa) << 10) | /* on LLMNR: c */ \ | |
177 | ((uint16_t) !!(tc) << 9) | \ | |
178 | ((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \ | |
179 | ((uint16_t) !!(ra) << 7) | \ | |
180 | ((uint16_t) !!(ad) << 5) | \ | |
181 | ((uint16_t) !!(cd) << 4) | \ | |
182 | ((uint16_t) ((rcode) & 15))) | |
3cb10d3a | 183 | |
322345fd LP |
184 | static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) { |
185 | return | |
186 | (unsigned) DNS_PACKET_ANCOUNT(p) + | |
187 | (unsigned) DNS_PACKET_NSCOUNT(p) + | |
188 | (unsigned) DNS_PACKET_ARCOUNT(p); | |
189 | } | |
74b2466e | 190 | |
51027656 | 191 | int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize, size_t max_size); |
46a58596 | 192 | int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t min_alloc_dsize, bool dnssec_checking_disabled); |
74b2466e | 193 | |
dbfbb6e7 DM |
194 | void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated); |
195 | ||
74b2466e LP |
196 | DnsPacket *dns_packet_ref(DnsPacket *p); |
197 | DnsPacket *dns_packet_unref(DnsPacket *p); | |
198 | ||
199 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref); | |
200 | ||
201 | int dns_packet_validate(DnsPacket *p); | |
202 | int dns_packet_validate_reply(DnsPacket *p); | |
623a4c97 | 203 | int dns_packet_validate_query(DnsPacket *p); |
74b2466e | 204 | |
8af5b883 LP |
205 | int dns_packet_is_reply_for(DnsPacket *p, const DnsResourceKey *key); |
206 | ||
623a4c97 | 207 | int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start); |
74b2466e LP |
208 | int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start); |
209 | int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start); | |
623a4c97 | 210 | int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start); |
74b2466e | 211 | int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start); |
2001c805 | 212 | int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start); |
a3db237b LP |
213 | int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, bool canonical_candidate, size_t *start); |
214 | int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, bool canonical_candidate, size_t *start); | |
58ab31d5 DR |
215 | int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, const DnsAnswerFlags flags, size_t *start); |
216 | int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, const DnsAnswerFlags flags, size_t *start, size_t *rdata_start); | |
f2ed4c69 | 217 | int dns_packet_append_opt(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, int rcode, size_t *start); |
f471bc11 LP |
218 | int dns_packet_append_question(DnsPacket *p, DnsQuestion *q); |
219 | int dns_packet_append_answer(DnsPacket *p, DnsAnswer *a); | |
74b2466e | 220 | |
9c5e12a4 | 221 | void dns_packet_truncate(DnsPacket *p, size_t sz); |
519ef046 | 222 | int dns_packet_truncate_opt(DnsPacket *p); |
9c5e12a4 | 223 | |
74b2466e | 224 | int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start); |
623a4c97 | 225 | int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start); |
74b2466e LP |
226 | int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start); |
227 | int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start); | |
228 | int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start); | |
229 | int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start); | |
2001c805 LP |
230 | int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start); |
231 | int dns_packet_read_name(DnsPacket *p, char **ret, bool allow_compression, size_t *start); | |
d2579eec LP |
232 | int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, bool *ret_cache_flush, size_t *start); |
233 | int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, bool *ret_cache_flush, size_t *start); | |
74b2466e | 234 | |
8ba9fd9c LP |
235 | void dns_packet_rewind(DnsPacket *p, size_t idx); |
236 | ||
74b2466e | 237 | int dns_packet_skip_question(DnsPacket *p); |
faa133f3 | 238 | int dns_packet_extract(DnsPacket *p); |
74b2466e | 239 | |
d830ebbd LP |
240 | static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket *p) { |
241 | /* Never cache data originating from localhost, under the | |
242 | * assumption, that it's coming from a locally DNS forwarder | |
243 | * or server, that is caching on its own. */ | |
244 | ||
245 | return in_addr_is_localhost(p->family, &p->sender) == 0; | |
246 | } | |
247 | ||
f3abbe25 | 248 | /* https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6 */ |
74b2466e LP |
249 | enum { |
250 | DNS_RCODE_SUCCESS = 0, | |
251 | DNS_RCODE_FORMERR = 1, | |
252 | DNS_RCODE_SERVFAIL = 2, | |
253 | DNS_RCODE_NXDOMAIN = 3, | |
254 | DNS_RCODE_NOTIMP = 4, | |
255 | DNS_RCODE_REFUSED = 5, | |
256 | DNS_RCODE_YXDOMAIN = 6, | |
257 | DNS_RCODE_YXRRSET = 7, | |
258 | DNS_RCODE_NXRRSET = 8, | |
259 | DNS_RCODE_NOTAUTH = 9, | |
260 | DNS_RCODE_NOTZONE = 10, | |
261 | DNS_RCODE_BADVERS = 16, | |
262 | DNS_RCODE_BADSIG = 16, /* duplicate value! */ | |
263 | DNS_RCODE_BADKEY = 17, | |
264 | DNS_RCODE_BADTIME = 18, | |
265 | DNS_RCODE_BADMODE = 19, | |
266 | DNS_RCODE_BADNAME = 20, | |
267 | DNS_RCODE_BADALG = 21, | |
268 | DNS_RCODE_BADTRUNC = 22, | |
6f21e066 | 269 | DNS_RCODE_BADCOOKIE = 23, |
f2ed4c69 LP |
270 | _DNS_RCODE_MAX_DEFINED, |
271 | _DNS_RCODE_MAX = 4095 /* 4 bit rcode in the header plus 8 bit rcode in OPT, makes 12 bit */ | |
74b2466e LP |
272 | }; |
273 | ||
274 | const char* dns_rcode_to_string(int i) _const_; | |
275 | int dns_rcode_from_string(const char *s) _pure_; | |
1716f6dc LP |
276 | |
277 | const char* dns_protocol_to_string(DnsProtocol p) _const_; | |
278 | DnsProtocol dns_protocol_from_string(const char *s) _pure_; | |
279 | ||
280 | #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) }) | |
281 | #define LLMNR_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x03 } }) | |
8db0d2f5 | 282 | |
0db4c90a | 283 | #define MDNS_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 251U) }) |
b6c5d46b | 284 | #define MDNS_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xfb } }) |
0db4c90a | 285 | |
931851e8 LP |
286 | static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family, bool authenticated) { |
287 | uint64_t f; | |
51323288 | 288 | |
931851e8 LP |
289 | /* Converts a protocol + family into a flags field as used in queries and responses */ |
290 | ||
291 | f = authenticated ? SD_RESOLVED_AUTHENTICATED : 0; | |
51323288 | 292 | |
106784eb DM |
293 | switch (protocol) { |
294 | case DNS_PROTOCOL_DNS: | |
931851e8 | 295 | return f|SD_RESOLVED_DNS; |
51323288 | 296 | |
106784eb | 297 | case DNS_PROTOCOL_LLMNR: |
931851e8 | 298 | return f|(family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4); |
51323288 | 299 | |
4e5bf5e1 | 300 | case DNS_PROTOCOL_MDNS: |
12e1893a | 301 | return f|(family == AF_INET6 ? SD_RESOLVED_MDNS_IPV6 : SD_RESOLVED_MDNS_IPV4); |
4e5bf5e1 | 302 | |
106784eb | 303 | default: |
12e1893a | 304 | return f; |
106784eb | 305 | } |
51323288 | 306 | } |
51027656 LP |
307 | |
308 | static inline size_t dns_packet_size_max(DnsPacket *p) { | |
309 | assert(p); | |
310 | ||
311 | /* Why not insist on a fully initialized max_size during DnsPacket construction? Well, this way it's easy to | |
312 | * allocate a transient, throw-away DnsPacket on the stack by simple zero initialization, without having to | |
313 | * deal with explicit field initialization. */ | |
314 | ||
315 | return p->max_size != 0 ? p->max_size : DNS_PACKET_SIZE_MAX; | |
316 | } |