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74b2466e LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | #pragma once | |
4 | ||
5 | /*** | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2014 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | ***/ | |
23 | ||
a0166609 | 24 | #include <netinet/ip.h> |
71d35b6b | 25 | #include <netinet/udp.h> |
74b2466e | 26 | |
74b2466e | 27 | #include "hashmap.h" |
7e8e0422 | 28 | #include "in-addr-util.h" |
71d35b6b TA |
29 | #include "macro.h" |
30 | #include "sparse-endian.h" | |
7e8e0422 LP |
31 | |
32 | typedef struct DnsPacketHeader DnsPacketHeader; | |
33 | typedef struct DnsPacket DnsPacket; | |
34 | ||
51323288 | 35 | #include "resolved-def.h" |
71d35b6b TA |
36 | #include "resolved-dns-answer.h" |
37 | #include "resolved-dns-question.h" | |
38 | #include "resolved-dns-rr.h" | |
74b2466e | 39 | |
1716f6dc LP |
40 | typedef enum DnsProtocol { |
41 | DNS_PROTOCOL_DNS, | |
42 | DNS_PROTOCOL_MDNS, | |
43 | DNS_PROTOCOL_LLMNR, | |
44 | _DNS_PROTOCOL_MAX, | |
45 | _DNS_PROTOCOL_INVALID = -1 | |
46 | } DnsProtocol; | |
47 | ||
74b2466e LP |
48 | struct DnsPacketHeader { |
49 | uint16_t id; | |
50 | be16_t flags; | |
51 | be16_t qdcount; | |
52 | be16_t ancount; | |
53 | be16_t nscount; | |
54 | be16_t arcount; | |
55 | }; | |
56 | ||
57 | #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader) | |
a0166609 | 58 | #define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr)) |
c73ce96b LP |
59 | |
60 | /* The various DNS protocols deviate in how large a packet can grow, | |
61 | but the TCP transport has a 16bit size field, hence that appears to | |
e1c95994 | 62 | be the absolute maximum. */ |
c73ce96b | 63 | #define DNS_PACKET_SIZE_MAX 0xFFFF |
e1c95994 LP |
64 | |
65 | /* RFC 1035 say 512 is the maximum, for classic unicast DNS */ | |
66 | #define DNS_PACKET_UNICAST_SIZE_MAX 512 | |
67 | ||
d74fb368 TG |
68 | /* With EDNS0 we can use larger packets, default to 4096, which is what is commonly used */ |
69 | #define DNS_PACKET_UNICAST_SIZE_LARGE_MAX 4096 | |
70 | ||
74b2466e LP |
71 | #define DNS_PACKET_SIZE_START 512 |
72 | ||
73 | struct DnsPacket { | |
74 | int n_ref; | |
1716f6dc | 75 | DnsProtocol protocol; |
74b2466e | 76 | size_t size, allocated, rindex; |
faa133f3 | 77 | void *_data; /* don't access directly, use DNS_PACKET_DATA()! */ |
74b2466e | 78 | Hashmap *names; /* For name compression */ |
faa133f3 LP |
79 | |
80 | /* Parsed data */ | |
81 | DnsQuestion *question; | |
82 | DnsAnswer *answer; | |
1716f6dc | 83 | |
dc61b7e4 | 84 | /* Packet reception metadata */ |
1716f6dc | 85 | int ifindex; |
623a4c97 | 86 | int family, ipproto; |
1716f6dc | 87 | union in_addr_union sender, destination; |
623a4c97 | 88 | uint16_t sender_port, destination_port; |
0dd25fb9 | 89 | uint32_t ttl; |
a4076574 | 90 | |
9c491563 DM |
91 | /* For support of truncated packets */ |
92 | DnsPacket *more; | |
93 | ||
a8812dd7 LP |
94 | bool on_stack:1; |
95 | bool extracted:1; | |
96 | bool refuse_compression:1; | |
97 | bool canonical_form:1; | |
74b2466e LP |
98 | }; |
99 | ||
100 | static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) { | |
101 | if (_unlikely_(!p)) | |
102 | return NULL; | |
103 | ||
faa133f3 LP |
104 | if (p->_data) |
105 | return p->_data; | |
74b2466e LP |
106 | |
107 | return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket)); | |
108 | } | |
109 | ||
110 | #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p)) | |
3cb10d3a LP |
111 | #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id |
112 | #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1) | |
113 | #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15) | |
8b757a38 | 114 | #define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1) |
ad867662 | 115 | #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1) |
8b757a38 DM |
116 | #define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1) |
117 | #define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1) | |
118 | #define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1) | |
119 | #define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1) | |
120 | #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15) | |
121 | ||
122 | /* LLMNR defines some bits differently */ | |
123 | #define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p) | |
124 | #define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p) | |
125 | ||
3cb10d3a LP |
126 | #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount) |
127 | #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount) | |
128 | #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount) | |
129 | #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount) | |
130 | ||
131 | #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \ | |
f0258e47 LP |
132 | (((uint16_t) !!(qr) << 15) | \ |
133 | ((uint16_t) ((opcode) & 15) << 11) | \ | |
134 | ((uint16_t) !!(aa) << 10) | /* on LLMNR: c */ \ | |
135 | ((uint16_t) !!(tc) << 9) | \ | |
136 | ((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \ | |
137 | ((uint16_t) !!(ra) << 7) | \ | |
138 | ((uint16_t) !!(ad) << 5) | \ | |
139 | ((uint16_t) !!(cd) << 4) | \ | |
140 | ((uint16_t) ((rcode) & 15))) | |
3cb10d3a | 141 | |
322345fd LP |
142 | static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) { |
143 | return | |
144 | (unsigned) DNS_PACKET_ANCOUNT(p) + | |
145 | (unsigned) DNS_PACKET_NSCOUNT(p) + | |
146 | (unsigned) DNS_PACKET_ARCOUNT(p); | |
147 | } | |
74b2466e | 148 | |
1716f6dc | 149 | int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu); |
24710c48 | 150 | int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu, bool dnssec_checking_disabled); |
74b2466e | 151 | |
dbfbb6e7 DM |
152 | void dns_packet_set_flags(DnsPacket *p, bool dnssec_checking_disabled, bool truncated); |
153 | ||
74b2466e LP |
154 | DnsPacket *dns_packet_ref(DnsPacket *p); |
155 | DnsPacket *dns_packet_unref(DnsPacket *p); | |
156 | ||
157 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref); | |
158 | ||
159 | int dns_packet_validate(DnsPacket *p); | |
160 | int dns_packet_validate_reply(DnsPacket *p); | |
623a4c97 | 161 | int dns_packet_validate_query(DnsPacket *p); |
74b2466e | 162 | |
623a4c97 | 163 | int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start); |
74b2466e LP |
164 | int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start); |
165 | int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start); | |
623a4c97 | 166 | int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start); |
74b2466e | 167 | int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start); |
2001c805 | 168 | int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start); |
74b2466e | 169 | int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start); |
2001c805 | 170 | int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, size_t *start); |
623a4c97 | 171 | int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start); |
a8812dd7 | 172 | int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start, size_t *rdata_start); |
7586f4d1 | 173 | int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start); |
74b2466e | 174 | |
9c5e12a4 TG |
175 | void dns_packet_truncate(DnsPacket *p, size_t sz); |
176 | ||
74b2466e | 177 | int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start); |
623a4c97 | 178 | int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start); |
74b2466e LP |
179 | int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start); |
180 | int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start); | |
181 | int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start); | |
182 | int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start); | |
2001c805 LP |
183 | int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start); |
184 | int dns_packet_read_name(DnsPacket *p, char **ret, bool allow_compression, size_t *start); | |
faa133f3 | 185 | int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start); |
74b2466e LP |
186 | int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start); |
187 | ||
8ba9fd9c LP |
188 | void dns_packet_rewind(DnsPacket *p, size_t idx); |
189 | ||
74b2466e | 190 | int dns_packet_skip_question(DnsPacket *p); |
faa133f3 | 191 | int dns_packet_extract(DnsPacket *p); |
74b2466e | 192 | |
d830ebbd LP |
193 | static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket *p) { |
194 | /* Never cache data originating from localhost, under the | |
195 | * assumption, that it's coming from a locally DNS forwarder | |
196 | * or server, that is caching on its own. */ | |
197 | ||
198 | return in_addr_is_localhost(p->family, &p->sender) == 0; | |
199 | } | |
200 | ||
74b2466e LP |
201 | enum { |
202 | DNS_RCODE_SUCCESS = 0, | |
203 | DNS_RCODE_FORMERR = 1, | |
204 | DNS_RCODE_SERVFAIL = 2, | |
205 | DNS_RCODE_NXDOMAIN = 3, | |
206 | DNS_RCODE_NOTIMP = 4, | |
207 | DNS_RCODE_REFUSED = 5, | |
208 | DNS_RCODE_YXDOMAIN = 6, | |
209 | DNS_RCODE_YXRRSET = 7, | |
210 | DNS_RCODE_NXRRSET = 8, | |
211 | DNS_RCODE_NOTAUTH = 9, | |
212 | DNS_RCODE_NOTZONE = 10, | |
213 | DNS_RCODE_BADVERS = 16, | |
214 | DNS_RCODE_BADSIG = 16, /* duplicate value! */ | |
215 | DNS_RCODE_BADKEY = 17, | |
216 | DNS_RCODE_BADTIME = 18, | |
217 | DNS_RCODE_BADMODE = 19, | |
218 | DNS_RCODE_BADNAME = 20, | |
219 | DNS_RCODE_BADALG = 21, | |
220 | DNS_RCODE_BADTRUNC = 22, | |
221 | _DNS_RCODE_MAX_DEFINED | |
222 | }; | |
223 | ||
224 | const char* dns_rcode_to_string(int i) _const_; | |
225 | int dns_rcode_from_string(const char *s) _pure_; | |
1716f6dc LP |
226 | |
227 | const char* dns_protocol_to_string(DnsProtocol p) _const_; | |
228 | DnsProtocol dns_protocol_from_string(const char *s) _pure_; | |
229 | ||
230 | #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) }) | |
231 | #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 | 232 | |
0db4c90a DM |
233 | #define MDNS_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 251U) }) |
234 | #define MDNS_MULTICAST_IPV6_ADDRESS ((struct in6_addr) { .s6_addr = { 0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0xfb } }) | |
235 | ||
931851e8 LP |
236 | static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family, bool authenticated) { |
237 | uint64_t f; | |
51323288 | 238 | |
931851e8 LP |
239 | /* Converts a protocol + family into a flags field as used in queries and responses */ |
240 | ||
241 | f = authenticated ? SD_RESOLVED_AUTHENTICATED : 0; | |
51323288 | 242 | |
106784eb DM |
243 | switch (protocol) { |
244 | case DNS_PROTOCOL_DNS: | |
931851e8 | 245 | return f|SD_RESOLVED_DNS; |
51323288 | 246 | |
106784eb | 247 | case DNS_PROTOCOL_LLMNR: |
931851e8 | 248 | return f|(family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4); |
51323288 | 249 | |
4e5bf5e1 DM |
250 | case DNS_PROTOCOL_MDNS: |
251 | return family == AF_INET6 ? SD_RESOLVED_MDNS_IPV6 : SD_RESOLVED_MDNS_IPV4; | |
252 | ||
106784eb DM |
253 | default: |
254 | break; | |
255 | } | |
256 | ||
51323288 LP |
257 | return 0; |
258 | } |