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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef NET_DNS_DNS_PROTOCOL_H_ | |
6 #define NET_DNS_DNS_PROTOCOL_H_ | |
7 | |
8 #include "base/basictypes.h" | |
9 #include "net/base/net_export.h" | |
10 | |
11 namespace net { | |
12 | |
13 namespace dns_protocol { | |
14 | |
15 static const uint16 kDefaultPort = 53; | |
16 static const uint16 kDefaultPortMulticast = 5353; | |
17 | |
18 // DNS packet consists of a header followed by questions and/or answers. | |
19 // For the meaning of specific fields, please see RFC 1035 and 2535 | |
20 | |
21 // Header format. | |
22 // 1 1 1 1 1 1 | |
23 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 | |
24 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
25 // | ID | | |
26 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
27 // |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE | | |
28 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
29 // | QDCOUNT | | |
30 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
31 // | ANCOUNT | | |
32 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
33 // | NSCOUNT | | |
34 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
35 // | ARCOUNT | | |
36 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
37 | |
38 // Question format. | |
39 // 1 1 1 1 1 1 | |
40 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 | |
41 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
42 // | | | |
43 // / QNAME / | |
44 // / / | |
45 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
46 // | QTYPE | | |
47 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
48 // | QCLASS | | |
49 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
50 | |
51 // Answer format. | |
52 // 1 1 1 1 1 1 | |
53 // 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 | |
54 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
55 // | | | |
56 // / / | |
57 // / NAME / | |
58 // | | | |
59 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
60 // | TYPE | | |
61 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
62 // | CLASS | | |
63 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
64 // | TTL | | |
65 // | | | |
66 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
67 // | RDLENGTH | | |
68 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| | |
69 // / RDATA / | |
70 // / / | |
71 // +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ | |
72 | |
73 #pragma pack(push) | |
74 #pragma pack(1) | |
75 | |
76 // On-the-wire header. All uint16 are in network order. | |
77 // Used internally in DnsQuery and DnsResponseParser. | |
78 struct NET_EXPORT_PRIVATE Header { | |
79 uint16 id; | |
80 uint16 flags; | |
81 uint16 qdcount; | |
82 uint16 ancount; | |
83 uint16 nscount; | |
84 uint16 arcount; | |
85 }; | |
86 | |
87 #pragma pack(pop) | |
88 | |
89 static const uint8 kLabelMask = 0xc0; | |
90 static const uint8 kLabelPointer = 0xc0; | |
91 static const uint8 kLabelDirect = 0x0; | |
92 static const uint16 kOffsetMask = 0x3fff; | |
93 | |
94 // In MDns the most significant bit of the rrclass is designated as the | |
95 // "cache-flush bit", as described in http://www.rfc-editor.org/rfc/rfc6762.txt | |
96 // section 10.2. | |
97 static const uint16 kMDnsClassMask = 0x7FFF; | |
98 | |
99 static const int kMaxNameLength = 255; | |
100 | |
101 // RFC 1035, section 4.2.1: Messages carried by UDP are restricted to 512 | |
102 // bytes (not counting the IP nor UDP headers). | |
103 static const int kMaxUDPSize = 512; | |
104 | |
105 // RFC 6762, section 17: Messages over the local link are restricted by the | |
106 // medium's MTU, and must be under 9000 bytes | |
107 static const int kMaxMulticastSize = 9000; | |
108 | |
109 // DNS class types. | |
110 static const uint16 kClassIN = 1; | |
111 | |
112 // DNS resource record types. See | |
113 // http://www.iana.org/assignments/dns-parameters | |
114 static const uint16 kTypeA = 1; | |
115 static const uint16 kTypeCNAME = 5; | |
116 static const uint16 kTypePTR = 12; | |
117 static const uint16 kTypeTXT = 16; | |
118 static const uint16 kTypeAAAA = 28; | |
119 static const uint16 kTypeSRV = 33; | |
120 static const uint16 kTypeNSEC = 47; | |
121 | |
122 | |
123 // DNS rcode values. | |
124 static const uint8 kRcodeMask = 0xf; | |
125 static const uint8 kRcodeNOERROR = 0; | |
126 static const uint8 kRcodeFORMERR = 1; | |
127 static const uint8 kRcodeSERVFAIL = 2; | |
128 static const uint8 kRcodeNXDOMAIN = 3; | |
129 static const uint8 kRcodeNOTIMP = 4; | |
130 static const uint8 kRcodeREFUSED = 5; | |
131 | |
132 // DNS flags. | |
133 static const uint16 kFlagResponse = 0x8000; | |
134 static const uint16 kFlagRA = 0x80; | |
135 static const uint16 kFlagRD = 0x100; | |
136 static const uint16 kFlagTC = 0x200; | |
137 static const uint16 kFlagAA = 0x400; | |
138 | |
139 } // namespace dns_protocol | |
140 | |
141 } // namespace net | |
142 | |
143 #endif // NET_DNS_DNS_PROTOCOL_H_ | |
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