]>
Commit | Line | Data |
---|---|---|
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 | ||
24 | #include <netinet/ip.h> | |
25 | #include <netinet/udp.h> | |
26 | ||
27 | #include "hashmap.h" | |
28 | #include "in-addr-util.h" | |
29 | #include "macro.h" | |
30 | #include "sparse-endian.h" | |
31 | ||
32 | typedef struct DnsPacketHeader DnsPacketHeader; | |
33 | typedef struct DnsPacket DnsPacket; | |
34 | ||
35 | #include "resolved-def.h" | |
36 | #include "resolved-dns-answer.h" | |
37 | #include "resolved-dns-question.h" | |
38 | #include "resolved-dns-rr.h" | |
39 | ||
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 | ||
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) | |
58 | #define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr)) | |
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 | |
62 | be the absolute maximum. */ | |
63 | #define DNS_PACKET_SIZE_MAX 0xFFFF | |
64 | ||
65 | /* RFC 1035 say 512 is the maximum, for classic unicast DNS */ | |
66 | #define DNS_PACKET_UNICAST_SIZE_MAX 512 | |
67 | ||
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 | ||
71 | #define DNS_PACKET_SIZE_START 512 | |
72 | ||
73 | struct DnsPacket { | |
74 | int n_ref; | |
75 | DnsProtocol protocol; | |
76 | size_t size, allocated, rindex; | |
77 | void *_data; /* don't access directly, use DNS_PACKET_DATA()! */ | |
78 | Hashmap *names; /* For name compression */ | |
79 | ||
80 | /* Parsed data */ | |
81 | DnsQuestion *question; | |
82 | DnsAnswer *answer; | |
83 | ||
84 | /* Packet reception metadata */ | |
85 | int ifindex; | |
86 | int family, ipproto; | |
87 | union in_addr_union sender, destination; | |
88 | uint16_t sender_port, destination_port; | |
89 | uint32_t ttl; | |
90 | ||
91 | bool extracted; | |
92 | bool refuse_compression; | |
93 | }; | |
94 | ||
95 | static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) { | |
96 | if (_unlikely_(!p)) | |
97 | return NULL; | |
98 | ||
99 | if (p->_data) | |
100 | return p->_data; | |
101 | ||
102 | return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket)); | |
103 | } | |
104 | ||
105 | #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p)) | |
106 | #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id | |
107 | #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1) | |
108 | #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15) | |
109 | #define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1) | |
110 | #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1) | |
111 | #define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1) | |
112 | #define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1) | |
113 | #define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1) | |
114 | #define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1) | |
115 | #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15) | |
116 | ||
117 | /* LLMNR defines some bits differently */ | |
118 | #define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p) | |
119 | #define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p) | |
120 | ||
121 | #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount) | |
122 | #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount) | |
123 | #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount) | |
124 | #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount) | |
125 | ||
126 | #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \ | |
127 | (((uint16_t) !!(qr) << 15) | \ | |
128 | ((uint16_t) ((opcode) & 15) << 11) | \ | |
129 | ((uint16_t) !!(aa) << 10) | /* on LLMNR: c */ \ | |
130 | ((uint16_t) !!(tc) << 9) | \ | |
131 | ((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \ | |
132 | ((uint16_t) !!(ra) << 7) | \ | |
133 | ((uint16_t) !!(ad) << 5) | \ | |
134 | ((uint16_t) !!(cd) << 4) | \ | |
135 | ((uint16_t) ((rcode) & 15))) | |
136 | ||
137 | static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) { | |
138 | return | |
139 | (unsigned) DNS_PACKET_ANCOUNT(p) + | |
140 | (unsigned) DNS_PACKET_NSCOUNT(p) + | |
141 | (unsigned) DNS_PACKET_ARCOUNT(p); | |
142 | } | |
143 | ||
144 | int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu); | |
145 | int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu); | |
146 | ||
147 | DnsPacket *dns_packet_ref(DnsPacket *p); | |
148 | DnsPacket *dns_packet_unref(DnsPacket *p); | |
149 | ||
150 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref); | |
151 | ||
152 | int dns_packet_validate(DnsPacket *p); | |
153 | int dns_packet_validate_reply(DnsPacket *p); | |
154 | int dns_packet_validate_query(DnsPacket *p); | |
155 | ||
156 | int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start); | |
157 | int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start); | |
158 | int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start); | |
159 | int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start); | |
160 | int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start); | |
161 | int dns_packet_append_raw_string(DnsPacket *p, const void *s, size_t size, size_t *start); | |
162 | int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start); | |
163 | int dns_packet_append_name(DnsPacket *p, const char *name, bool allow_compression, size_t *start); | |
164 | int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start); | |
165 | int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start); | |
166 | int dns_packet_append_opt_rr(DnsPacket *p, uint16_t max_udp_size, bool edns0_do, size_t *start); | |
167 | ||
168 | void dns_packet_truncate(DnsPacket *p, size_t sz); | |
169 | ||
170 | int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start); | |
171 | int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start); | |
172 | int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start); | |
173 | int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start); | |
174 | int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start); | |
175 | int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start); | |
176 | int dns_packet_read_raw_string(DnsPacket *p, const void **ret, size_t *size, size_t *start); | |
177 | int dns_packet_read_name(DnsPacket *p, char **ret, bool allow_compression, size_t *start); | |
178 | int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start); | |
179 | int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start); | |
180 | ||
181 | void dns_packet_rewind(DnsPacket *p, size_t idx); | |
182 | ||
183 | int dns_packet_skip_question(DnsPacket *p); | |
184 | int dns_packet_extract(DnsPacket *p); | |
185 | ||
186 | static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket *p) { | |
187 | /* Never cache data originating from localhost, under the | |
188 | * assumption, that it's coming from a locally DNS forwarder | |
189 | * or server, that is caching on its own. */ | |
190 | ||
191 | return in_addr_is_localhost(p->family, &p->sender) == 0; | |
192 | } | |
193 | ||
194 | enum { | |
195 | DNS_RCODE_SUCCESS = 0, | |
196 | DNS_RCODE_FORMERR = 1, | |
197 | DNS_RCODE_SERVFAIL = 2, | |
198 | DNS_RCODE_NXDOMAIN = 3, | |
199 | DNS_RCODE_NOTIMP = 4, | |
200 | DNS_RCODE_REFUSED = 5, | |
201 | DNS_RCODE_YXDOMAIN = 6, | |
202 | DNS_RCODE_YXRRSET = 7, | |
203 | DNS_RCODE_NXRRSET = 8, | |
204 | DNS_RCODE_NOTAUTH = 9, | |
205 | DNS_RCODE_NOTZONE = 10, | |
206 | DNS_RCODE_BADVERS = 16, | |
207 | DNS_RCODE_BADSIG = 16, /* duplicate value! */ | |
208 | DNS_RCODE_BADKEY = 17, | |
209 | DNS_RCODE_BADTIME = 18, | |
210 | DNS_RCODE_BADMODE = 19, | |
211 | DNS_RCODE_BADNAME = 20, | |
212 | DNS_RCODE_BADALG = 21, | |
213 | DNS_RCODE_BADTRUNC = 22, | |
214 | _DNS_RCODE_MAX_DEFINED | |
215 | }; | |
216 | ||
217 | const char* dns_rcode_to_string(int i) _const_; | |
218 | int dns_rcode_from_string(const char *s) _pure_; | |
219 | ||
220 | const char* dns_protocol_to_string(DnsProtocol p) _const_; | |
221 | DnsProtocol dns_protocol_from_string(const char *s) _pure_; | |
222 | ||
223 | #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) }) | |
224 | #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 } }) | |
225 | ||
226 | #define DNSKEY_FLAG_ZONE_KEY (1u << 8) | |
227 | #define DNSKEY_FLAG_SEP (1u << 0) | |
228 | ||
229 | static inline uint16_t dnskey_to_flags(const DnsResourceRecord *rr) { | |
230 | return (rr->dnskey.zone_key_flag * DNSKEY_FLAG_ZONE_KEY | | |
231 | rr->dnskey.sep_flag * DNSKEY_FLAG_SEP); | |
232 | } | |
233 | ||
234 | /* http://tools.ietf.org/html/rfc4034#appendix-A.1 */ | |
235 | enum { | |
236 | DNSSEC_ALGORITHM_RSAMD5 = 1, | |
237 | DNSSEC_ALGORITHM_DH, | |
238 | DNSSEC_ALGORITHM_DSA, | |
239 | DNSSEC_ALGORITHM_ECC, | |
240 | DNSSEC_ALGORITHM_RSASHA1, | |
241 | DNSSEC_ALGORITHM_DSA_NSEC3_SHA1, | |
242 | DNSSEC_ALGORITHM_RSASHA1_NSEC3_SHA1, | |
243 | DNSSEC_ALGORITHM_INDIRECT = 252, | |
244 | DNSSEC_ALGORITHM_PRIVATEDNS, | |
245 | DNSSEC_ALGORITHM_PRIVATEOID, | |
246 | _DNSSEC_ALGORITHM_MAX_DEFINED | |
247 | }; | |
248 | ||
249 | const char* dnssec_algorithm_to_string(int i) _const_; | |
250 | int dnssec_algorithm_from_string(const char *s) _pure_; | |
251 | ||
252 | static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol, int family) { | |
253 | ||
254 | /* Converts a protocol + family into a flags field as used in queries */ | |
255 | ||
256 | switch (protocol) { | |
257 | case DNS_PROTOCOL_DNS: | |
258 | return SD_RESOLVED_DNS; | |
259 | ||
260 | case DNS_PROTOCOL_LLMNR: | |
261 | return family == AF_INET6 ? SD_RESOLVED_LLMNR_IPV6 : SD_RESOLVED_LLMNR_IPV4; | |
262 | ||
263 | default: | |
264 | break; | |
265 | } | |
266 | ||
267 | return 0; | |
268 | } |