1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
6 This file is part of systemd.
8 Copyright 2014 Lennart Poettering
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.
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.
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/>.
24 #include <netinet/ip.h>
25 #include <netinet/udp.h>
28 #include "in-addr-util.h"
30 #include "sparse-endian.h"
32 typedef struct DnsPacketHeader DnsPacketHeader
;
33 typedef struct DnsPacket DnsPacket
;
35 #include "resolved-def.h"
36 #include "resolved-dns-answer.h"
37 #include "resolved-dns-question.h"
38 #include "resolved-dns-rr.h"
40 typedef enum DnsProtocol
{
45 _DNS_PROTOCOL_INVALID
= -1
48 struct DnsPacketHeader
{
57 #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader)
58 #define UDP_PACKET_HEADER_SIZE (sizeof(struct iphdr) + sizeof(struct udphdr))
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
65 /* RFC 1035 say 512 is the maximum, for classic unicast DNS */
66 #define DNS_PACKET_UNICAST_SIZE_MAX 512
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
71 #define DNS_PACKET_SIZE_START 512
76 size_t size
, allocated
, rindex
;
77 void *_data
; /* don't access directly, use DNS_PACKET_DATA()! */
78 Hashmap
*names
; /* For name compression */
81 DnsQuestion
*question
;
84 /* Packet reception metadata */
87 union in_addr_union sender
, destination
;
88 uint16_t sender_port
, destination_port
;
91 /* For support of truncated packets */
96 bool refuse_compression
:1;
97 bool canonical_form
:1;
100 static inline uint8_t* DNS_PACKET_DATA(DnsPacket
*p
) {
107 return ((uint8_t*) p
) + ALIGN(sizeof(DnsPacket
));
110 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
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)
114 #define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1)
115 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
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)
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)
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)
131 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
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)))
142 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket
*p
) {
144 (unsigned) DNS_PACKET_ANCOUNT(p
) +
145 (unsigned) DNS_PACKET_NSCOUNT(p
) +
146 (unsigned) DNS_PACKET_ARCOUNT(p
);
149 int dns_packet_new(DnsPacket
**p
, DnsProtocol protocol
, size_t mtu
);
150 int dns_packet_new_query(DnsPacket
**p
, DnsProtocol protocol
, size_t mtu
, bool dnssec_checking_disabled
);
152 void dns_packet_set_flags(DnsPacket
*p
, bool dnssec_checking_disabled
, bool truncated
);
154 DnsPacket
*dns_packet_ref(DnsPacket
*p
);
155 DnsPacket
*dns_packet_unref(DnsPacket
*p
);
157 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket
*, dns_packet_unref
);
159 int dns_packet_validate(DnsPacket
*p
);
160 int dns_packet_validate_reply(DnsPacket
*p
);
161 int dns_packet_validate_query(DnsPacket
*p
);
163 int dns_packet_append_blob(DnsPacket
*p
, const void *d
, size_t sz
, size_t *start
);
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
);
166 int dns_packet_append_uint32(DnsPacket
*p
, uint32_t v
, size_t *start
);
167 int dns_packet_append_string(DnsPacket
*p
, const char *s
, size_t *start
);
168 int dns_packet_append_raw_string(DnsPacket
*p
, const void *s
, size_t size
, size_t *start
);
169 int dns_packet_append_label(DnsPacket
*p
, const char *s
, size_t l
, size_t *start
);
170 int dns_packet_append_name(DnsPacket
*p
, const char *name
, bool allow_compression
, size_t *start
);
171 int dns_packet_append_key(DnsPacket
*p
, const DnsResourceKey
*key
, size_t *start
);
172 int dns_packet_append_rr(DnsPacket
*p
, const DnsResourceRecord
*rr
, size_t *start
, size_t *rdata_start
);
173 int dns_packet_append_opt_rr(DnsPacket
*p
, uint16_t max_udp_size
, bool edns0_do
, size_t *start
);
175 void dns_packet_truncate(DnsPacket
*p
, size_t sz
);
177 int dns_packet_read(DnsPacket
*p
, size_t sz
, const void **ret
, size_t *start
);
178 int dns_packet_read_blob(DnsPacket
*p
, void *d
, size_t sz
, size_t *start
);
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
);
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
);
185 int dns_packet_read_key(DnsPacket
*p
, DnsResourceKey
**ret
, size_t *start
);
186 int dns_packet_read_rr(DnsPacket
*p
, DnsResourceRecord
**ret
, size_t *start
);
188 void dns_packet_rewind(DnsPacket
*p
, size_t idx
);
190 int dns_packet_skip_question(DnsPacket
*p
);
191 int dns_packet_extract(DnsPacket
*p
);
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. */
198 return in_addr_is_localhost(p
->family
, &p
->sender
) == 0;
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
224 const char* dns_rcode_to_string(int i
) _const_
;
225 int dns_rcode_from_string(const char *s
) _pure_
;
227 const char* dns_protocol_to_string(DnsProtocol p
) _const_
;
228 DnsProtocol
dns_protocol_from_string(const char *s
) _pure_
;
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 } })
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 } })
236 static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol
, int family
, bool authenticated
) {
239 /* Converts a protocol + family into a flags field as used in queries and responses */
241 f
= authenticated
? SD_RESOLVED_AUTHENTICATED
: 0;
244 case DNS_PROTOCOL_DNS
:
245 return f
|SD_RESOLVED_DNS
;
247 case DNS_PROTOCOL_LLMNR
:
248 return f
|(family
== AF_INET6
? SD_RESOLVED_LLMNR_IPV6
: SD_RESOLVED_LLMNR_IPV4
);
250 case DNS_PROTOCOL_MDNS
:
251 return family
== AF_INET6
? SD_RESOLVED_MDNS_IPV6
: SD_RESOLVED_MDNS_IPV4
;