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 */
79 size_t opt_start
, opt_size
;
82 DnsQuestion
*question
;
84 DnsResourceRecord
*opt
;
86 /* Packet reception metadata */
89 union in_addr_union sender
, destination
;
90 uint16_t sender_port
, destination_port
;
93 /* For support of truncated packets */
98 bool refuse_compression
:1;
99 bool canonical_form
:1;
102 static inline uint8_t* DNS_PACKET_DATA(DnsPacket
*p
) {
109 return ((uint8_t*) p
) + ALIGN(sizeof(DnsPacket
));
112 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
113 #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
114 #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
115 #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
116 #define DNS_PACKET_AA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1)
117 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
118 #define DNS_PACKET_RD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1)
119 #define DNS_PACKET_RA(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 7) & 1)
120 #define DNS_PACKET_AD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 5) & 1)
121 #define DNS_PACKET_CD(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 4) & 1)
122 #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
124 /* LLMNR defines some bits differently */
125 #define DNS_PACKET_LLMNR_C(p) DNS_PACKET_AA(p)
126 #define DNS_PACKET_LLMNR_T(p) DNS_PACKET_RD(p)
128 #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
129 #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
130 #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
131 #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
133 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
134 (((uint16_t) !!(qr) << 15) | \
135 ((uint16_t) ((opcode) & 15) << 11) | \
136 ((uint16_t) !!(aa) << 10) | /* on LLMNR: c */ \
137 ((uint16_t) !!(tc) << 9) | \
138 ((uint16_t) !!(rd) << 8) | /* on LLMNR: t */ \
139 ((uint16_t) !!(ra) << 7) | \
140 ((uint16_t) !!(ad) << 5) | \
141 ((uint16_t) !!(cd) << 4) | \
142 ((uint16_t) ((rcode) & 15)))
144 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket
*p
) {
146 (unsigned) DNS_PACKET_ANCOUNT(p
) +
147 (unsigned) DNS_PACKET_NSCOUNT(p
) +
148 (unsigned) DNS_PACKET_ARCOUNT(p
);
151 int dns_packet_new(DnsPacket
**p
, DnsProtocol protocol
, size_t mtu
);
152 int dns_packet_new_query(DnsPacket
**p
, DnsProtocol protocol
, size_t mtu
, bool dnssec_checking_disabled
);
154 void dns_packet_set_flags(DnsPacket
*p
, bool dnssec_checking_disabled
, bool truncated
);
156 DnsPacket
*dns_packet_ref(DnsPacket
*p
);
157 DnsPacket
*dns_packet_unref(DnsPacket
*p
);
159 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket
*, dns_packet_unref
);
161 int dns_packet_validate(DnsPacket
*p
);
162 int dns_packet_validate_reply(DnsPacket
*p
);
163 int dns_packet_validate_query(DnsPacket
*p
);
165 int dns_packet_is_reply_for(DnsPacket
*p
, const DnsResourceKey
*key
);
167 int dns_packet_append_blob(DnsPacket
*p
, const void *d
, size_t sz
, size_t *start
);
168 int dns_packet_append_uint8(DnsPacket
*p
, uint8_t v
, size_t *start
);
169 int dns_packet_append_uint16(DnsPacket
*p
, uint16_t v
, size_t *start
);
170 int dns_packet_append_uint32(DnsPacket
*p
, uint32_t v
, size_t *start
);
171 int dns_packet_append_string(DnsPacket
*p
, const char *s
, size_t *start
);
172 int dns_packet_append_raw_string(DnsPacket
*p
, const void *s
, size_t size
, size_t *start
);
173 int dns_packet_append_label(DnsPacket
*p
, const char *s
, size_t l
, bool canonical_candidate
, size_t *start
);
174 int dns_packet_append_name(DnsPacket
*p
, const char *name
, bool allow_compression
, bool canonical_candidate
, size_t *start
);
175 int dns_packet_append_key(DnsPacket
*p
, const DnsResourceKey
*key
, size_t *start
);
176 int dns_packet_append_rr(DnsPacket
*p
, const DnsResourceRecord
*rr
, size_t *start
, size_t *rdata_start
);
177 int dns_packet_append_opt(DnsPacket
*p
, uint16_t max_udp_size
, bool edns0_do
, size_t *start
);
179 void dns_packet_truncate(DnsPacket
*p
, size_t sz
);
180 int dns_packet_truncate_opt(DnsPacket
*p
);
182 int dns_packet_read(DnsPacket
*p
, size_t sz
, const void **ret
, size_t *start
);
183 int dns_packet_read_blob(DnsPacket
*p
, void *d
, size_t sz
, size_t *start
);
184 int dns_packet_read_uint8(DnsPacket
*p
, uint8_t *ret
, size_t *start
);
185 int dns_packet_read_uint16(DnsPacket
*p
, uint16_t *ret
, size_t *start
);
186 int dns_packet_read_uint32(DnsPacket
*p
, uint32_t *ret
, size_t *start
);
187 int dns_packet_read_string(DnsPacket
*p
, char **ret
, size_t *start
);
188 int dns_packet_read_raw_string(DnsPacket
*p
, const void **ret
, size_t *size
, size_t *start
);
189 int dns_packet_read_name(DnsPacket
*p
, char **ret
, bool allow_compression
, size_t *start
);
190 int dns_packet_read_key(DnsPacket
*p
, DnsResourceKey
**ret
, bool *ret_cache_flush
, size_t *start
);
191 int dns_packet_read_rr(DnsPacket
*p
, DnsResourceRecord
**ret
, bool *ret_cache_flush
, size_t *start
);
193 void dns_packet_rewind(DnsPacket
*p
, size_t idx
);
195 int dns_packet_skip_question(DnsPacket
*p
);
196 int dns_packet_extract(DnsPacket
*p
);
198 static inline bool DNS_PACKET_SHALL_CACHE(DnsPacket
*p
) {
199 /* Never cache data originating from localhost, under the
200 * assumption, that it's coming from a locally DNS forwarder
201 * or server, that is caching on its own. */
203 return in_addr_is_localhost(p
->family
, &p
->sender
) == 0;
207 DNS_RCODE_SUCCESS
= 0,
208 DNS_RCODE_FORMERR
= 1,
209 DNS_RCODE_SERVFAIL
= 2,
210 DNS_RCODE_NXDOMAIN
= 3,
211 DNS_RCODE_NOTIMP
= 4,
212 DNS_RCODE_REFUSED
= 5,
213 DNS_RCODE_YXDOMAIN
= 6,
214 DNS_RCODE_YXRRSET
= 7,
215 DNS_RCODE_NXRRSET
= 8,
216 DNS_RCODE_NOTAUTH
= 9,
217 DNS_RCODE_NOTZONE
= 10,
218 DNS_RCODE_BADVERS
= 16,
219 DNS_RCODE_BADSIG
= 16, /* duplicate value! */
220 DNS_RCODE_BADKEY
= 17,
221 DNS_RCODE_BADTIME
= 18,
222 DNS_RCODE_BADMODE
= 19,
223 DNS_RCODE_BADNAME
= 20,
224 DNS_RCODE_BADALG
= 21,
225 DNS_RCODE_BADTRUNC
= 22,
226 _DNS_RCODE_MAX_DEFINED
229 const char* dns_rcode_to_string(int i
) _const_
;
230 int dns_rcode_from_string(const char *s
) _pure_
;
232 const char* dns_protocol_to_string(DnsProtocol p
) _const_
;
233 DnsProtocol
dns_protocol_from_string(const char *s
) _pure_
;
235 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
236 #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 } })
238 #define MDNS_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 251U) })
239 #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 } })
241 static inline uint64_t SD_RESOLVED_FLAGS_MAKE(DnsProtocol protocol
, int family
, bool authenticated
) {
244 /* Converts a protocol + family into a flags field as used in queries and responses */
246 f
= authenticated
? SD_RESOLVED_AUTHENTICATED
: 0;
249 case DNS_PROTOCOL_DNS
:
250 return f
|SD_RESOLVED_DNS
;
252 case DNS_PROTOCOL_LLMNR
:
253 return f
|(family
== AF_INET6
? SD_RESOLVED_LLMNR_IPV6
: SD_RESOLVED_LLMNR_IPV4
);
255 case DNS_PROTOCOL_MDNS
:
256 return family
== AF_INET6
? SD_RESOLVED_MDNS_IPV6
: SD_RESOLVED_MDNS_IPV4
;