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;
85 static inline uint8_t* DNS_PACKET_DATA(DnsPacket *p) {
92 return ((uint8_t*) p) + ALIGN(sizeof(DnsPacket));
95 #define DNS_PACKET_HEADER(p) ((DnsPacketHeader*) DNS_PACKET_DATA(p))
96 #define DNS_PACKET_ID(p) DNS_PACKET_HEADER(p)->id
97 #define DNS_PACKET_QR(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 15) & 1)
98 #define DNS_PACKET_OPCODE(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 11) & 15)
99 #define DNS_PACKET_RCODE(p) (be16toh(DNS_PACKET_HEADER(p)->flags) & 15)
100 #define DNS_PACKET_TC(p) ((be16toh(DNS_PACKET_HEADER(p)->flags) >> 9) & 1)
101 #define DNS_PACKET_QDCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->qdcount)
102 #define DNS_PACKET_ANCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->ancount)
103 #define DNS_PACKET_NSCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->nscount)
104 #define DNS_PACKET_ARCOUNT(p) be16toh(DNS_PACKET_HEADER(p)->arcount)
106 #define DNS_PACKET_MAKE_FLAGS(qr, opcode, aa, tc, rd, ra, ad, cd, rcode) \
107 (((uint16_t) !!qr << 15) | \
108 ((uint16_t) (opcode & 15) << 11) | \
109 ((uint16_t) !!aa << 10) | \
110 ((uint16_t) !!tc << 9) | \
111 ((uint16_t) !!rd << 8) | \
112 ((uint16_t) !!ra << 7) | \
113 ((uint16_t) !!ad << 5) | \
114 ((uint16_t) !!cd << 4) | \
115 ((uint16_t) (rcode & 15)))
117 static inline unsigned DNS_PACKET_RRCOUNT(DnsPacket *p) {
119 (unsigned) DNS_PACKET_ANCOUNT(p) +
120 (unsigned) DNS_PACKET_NSCOUNT(p) +
121 (unsigned) DNS_PACKET_ARCOUNT(p);
124 int dns_packet_new(DnsPacket **p, DnsProtocol protocol, size_t mtu);
125 int dns_packet_new_query(DnsPacket **p, DnsProtocol protocol, size_t mtu);
127 DnsPacket *dns_packet_ref(DnsPacket *p);
128 DnsPacket *dns_packet_unref(DnsPacket *p);
130 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsPacket*, dns_packet_unref);
132 int dns_packet_validate(DnsPacket *p);
133 int dns_packet_validate_reply(DnsPacket *p);
135 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start);
136 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start);
137 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start);
138 int dns_packet_append_label(DnsPacket *p, const char *s, size_t l, size_t *start);
139 int dns_packet_append_name(DnsPacket *p, const char *name, size_t *start);
140 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start);
142 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start);
143 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start);
144 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start);
145 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start);
146 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start);
147 int dns_packet_read_name(DnsPacket *p, char **ret, size_t *start);
148 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start);
149 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start);
151 void dns_packet_rewind(DnsPacket *p, size_t idx);
153 int dns_packet_skip_question(DnsPacket *p);
154 int dns_packet_extract(DnsPacket *p);
157 DNS_RCODE_SUCCESS = 0,
158 DNS_RCODE_FORMERR = 1,
159 DNS_RCODE_SERVFAIL = 2,
160 DNS_RCODE_NXDOMAIN = 3,
161 DNS_RCODE_NOTIMP = 4,
162 DNS_RCODE_REFUSED = 5,
163 DNS_RCODE_YXDOMAIN = 6,
164 DNS_RCODE_YXRRSET = 7,
165 DNS_RCODE_NXRRSET = 8,
166 DNS_RCODE_NOTAUTH = 9,
167 DNS_RCODE_NOTZONE = 10,
168 DNS_RCODE_BADVERS = 16,
169 DNS_RCODE_BADSIG = 16, /* duplicate value! */
170 DNS_RCODE_BADKEY = 17,
171 DNS_RCODE_BADTIME = 18,
172 DNS_RCODE_BADMODE = 19,
173 DNS_RCODE_BADNAME = 20,
174 DNS_RCODE_BADALG = 21,
175 DNS_RCODE_BADTRUNC = 22,
176 _DNS_RCODE_MAX_DEFINED
179 const char* dns_rcode_to_string(int i) _const_;
180 int dns_rcode_from_string(const char *s) _pure_;
182 const char* dns_protocol_to_string(DnsProtocol p) _const_;
183 DnsProtocol dns_protocol_from_string(const char *s) _pure_;
185 #define LLMNR_MULTICAST_IPV4_ADDRESS ((struct in_addr) { .s_addr = htobe32(224U << 24 | 252U) })
186 #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 } })