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/>.
27 #include "sparse-endian.h"
29 #include "in-addr-util.h"
31 typedef struct DnsPacketHeader DnsPacketHeader;
32 typedef struct DnsPacket DnsPacket;
34 #include "resolved-dns-rr.h"
35 #include "resolved-dns-question.h"
36 #include "resolved-dns-answer.h"
38 typedef enum DnsProtocol {
43 _DNS_PROTOCOL_INVALID = -1
46 struct DnsPacketHeader {
55 #define DNS_PACKET_HEADER_SIZE sizeof(DnsPacketHeader)
57 /* The various DNS protocols deviate in how large a packet can grow,
58 but the TCP transport has a 16bit size field, hence that appears to
59 be the absolute maximum. */
60 #define DNS_PACKET_SIZE_MAX 0xFFFF
62 /* RFC 1035 say 512 is the maximum, for classic unicast DNS */
63 #define DNS_PACKET_UNICAST_SIZE_MAX 512
65 #define DNS_PACKET_SIZE_START 512
70 size_t size, allocated, rindex;
71 void *_data; /* don't access directly, use DNS_PACKET_DATA()! */
72 Hashmap *names; /* For name compression */
75 DnsQuestion *question;
78 /* Packet reception meta data */
81 union in_addr_union sender, destination;
82 uint16_t sender_port, destination_port;
86 static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
93 return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket));
96 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
97 #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
98 #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
99 #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
100 #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
101 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
102 #define DNS_PACKET_C(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 10) & 1)
103 #define DNS_PACKET_T(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 8) & 1)
104 #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
105 #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
106 #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
107 #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
109 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
110 (((uint16_t) !!qr << 15) | \
111 ((uint16_t) (opcode & 15) << 11) | \
112 ((uint16_t) !!aa << 10) | \
113 ((uint16_t) !!tc << 9) | \
114 ((uint16_t) !!rd << 8) | \
115 ((uint16_t) !!ra << 7) | \
116 ((uint16_t) !!ad << 5) | \
117 ((uint16_t) !!cd << 4) | \
118 ((uint16_t) (rcode & 15)))
120 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
122 (unsigned) DNS_PACKET_ANCOUNT(p) +
123 (unsigned) DNS_PACKET_NSCOUNT(p) +
124 (unsigned) DNS_PACKET_ARCOUNT(p);
127 int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
128 int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu);
130 DnsPacket *dns_packet_ref(DnsPacket *p);
131 DnsPacket *dns_packet_unref(DnsPacket *p);
133 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref);
135 int dns_packet_validate(DnsPacket *p);
136 int dns_packet_validate_reply(DnsPacket *p);
137 int dns_packet_validate_query(DnsPacket *p);
139 int dns_packet_append_blob(DnsPacket *p, const void *d, size_t sz, size_t *start);
140 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start);
141 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start);
142 int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start);
143 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
144 int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start);
145 int dns_packet_append_name(DnsPacket *p, const char *name, size_t *start);
146 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *key, size_t *start);
147 int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start);
149 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
150 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start);
151 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start);
152 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start);
153 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start);
154 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start);
155 int dns_packet_read_name(DnsPacket *p, char **ret, size_t *start);
156 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start);
157 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
159 void dns_packet_rewind(DnsPacket *p, size_t idx);
161 int dns_packet_skip_question(DnsPacket *p);
162 int dns_packet_extract(DnsPacket *p);
165 DNS_RCODE_SUCCESS = 0,
166 DNS_RCODE_FORMERR = 1,
167 DNS_RCODE_SERVFAIL = 2,
168 DNS_RCODE_NXDOMAIN = 3,
169 DNS_RCODE_NOTIMP = 4,
170 DNS_RCODE_REFUSED = 5,
171 DNS_RCODE_YXDOMAIN = 6,
172 DNS_RCODE_YXRRSET = 7,
173 DNS_RCODE_NXRRSET = 8,
174 DNS_RCODE_NOTAUTH = 9,
175 DNS_RCODE_NOTZONE = 10,
176 DNS_RCODE_BADVERS = 16,
177 DNS_RCODE_BADSIG = 16, /* duplicate value! */
178 DNS_RCODE_BADKEY = 17,
179 DNS_RCODE_BADTIME = 18,
180 DNS_RCODE_BADMODE = 19,
181 DNS_RCODE_BADNAME = 20,
182 DNS_RCODE_BADALG = 21,
183 DNS_RCODE_BADTRUNC = 22,
184 _DNS_RCODE_MAX_DEFINED
187 const char* dns_rcode_to_string(int i) _const_;
188 int dns_rcode_from_string(const char *s) _pure_;
190 const char* dns_protocol_to_string(DnsProtocol p) _const_;
191 DnsProtocol dns_protocol_from_string(const char *s) _pure_;
193 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
194 #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 } })
196 #define DNSKEY_FLAG_ZONE_KEY (1u << 8)
197 #define DNSKEY_FLAG_SEP (1u << 0)
199 static inline uint16_t dnskey_to_flags(const DnsResourceRecord *rr) {
200 return (rr->dnskey.zone_key_flag * DNSKEY_FLAG_ZONE_KEY |
201 rr->dnskey.sep_flag * DNSKEY_FLAG_SEP);