source: trip-planner-front/node_modules/dns-packet/README.md@ 76712b2

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1# dns-packet
2
3An [abstract-encoding](https://github.com/mafintosh/abstract-encoding) compliant module for encoding / decoding DNS packets.
4Lifted out of [multicast-dns](https://github.com/mafintosh/multicast-dns) as a separate module.
5
6```
7npm install dns-packet
8```
9
10[![build status](https://travis-ci.org/mafintosh/dns-packet.svg?branch=master)](https://travis-ci.org/mafintosh/dns-packet)
11
12## Usage
13
14``` js
15var packet = require('dns-packet')
16var dgram = require('dgram')
17
18var socket = dgram.createSocket('udp4')
19
20var buf = packet.encode({
21 type: 'query',
22 id: 1,
23 flags: packet.RECURSION_DESIRED,
24 questions: [{
25 type: 'A',
26 name: 'google.com'
27 }]
28})
29
30socket.on('message', function (message) {
31 console.log(packet.decode(message)) // prints out a response from google dns
32})
33
34socket.send(buf, 0, buf.length, 53, '8.8.8.8')
35```
36
37## API
38
39#### `var buf = packets.encode(packet, [buf], [offset])`
40
41Encodes a DNS packet into a buffer.
42
43#### `var packet = packets.decode(buf, [offset])`
44
45Decode a DNS packet from a buffer
46
47#### `var len = packets.encodingLength(packet)`
48
49Returns how many bytes are needed to encode the DNS packet
50
51## Packets
52
53Packets look like this
54
55``` js
56{
57 type: 'query|response',
58 id: optionalIdNumber,
59 flags: optionalBitFlags,
60 questions: [...],
61 answers: [...],
62 additionals: [...],
63 authorities: [...]
64}
65```
66
67The bit flags available are
68
69``` js
70packet.RECURSION_DESIRED
71packet.RECURSION_AVAILABLE
72packet.TRUNCATED_RESPONSE
73packet.AUTHORITATIVE_ANSWER
74packet.AUTHENTIC_DATA
75packet.CHECKING_DISABLED
76```
77
78To use more than one flag bitwise-or them together
79
80``` js
81var flags = packet.RECURSION_DESIRED | packet.RECURSION_AVAILABLE
82```
83
84And to check for a flag use bitwise-and
85
86``` js
87var isRecursive = message.flags & packet.RECURSION_DESIRED
88```
89
90A question looks like this
91
92``` js
93{
94 type: 'A', // or SRV, AAAA, etc
95 name: 'google.com' // which record are you looking for
96}
97```
98
99And an answers, additional, or authority looks like this
100
101``` js
102{
103 type: 'A', // or SRV, AAAA, etc
104 name: 'google.com', // which name is this record for
105 ttl: optionalTimeToLiveInSeconds,
106 (record specific data, see below)
107}
108```
109
110Currently the different available records are
111
112#### `A`
113
114``` js
115{
116 data: 'IPv4 address' // fx 127.0.0.1
117}
118```
119
120#### `AAAA`
121
122``` js
123{
124 data: 'IPv6 address' // fx fe80::1
125}
126```
127
128#### `TXT`
129
130``` js
131{
132 data: Buffer('some text')
133}
134```
135
136#### `NS`
137
138``` js
139{
140 data: nameServer
141}
142```
143
144#### `NULL`
145
146``` js
147{
148 data: Buffer('any binary data')
149}
150```
151
152#### `SOA`
153
154``` js
155{
156 data:
157 {
158 mname: domainName,
159 rname: mailbox,
160 serial: zoneSerial,
161 refresh: refreshInterval,
162 retry: retryInterval,
163 expire: expireInterval,
164 minimum: minimumTTL
165 }
166}
167```
168
169#### `SRV`
170
171``` js
172{
173 data: {
174 port: servicePort,
175 target: serviceHostName,
176 priority: optionalServicePriority,
177 weight: optionalServiceWeight
178 }
179}
180```
181
182#### `HINFO`
183
184``` js
185{
186 data: {
187 cpu: 'cpu info',
188 os: 'os info'
189 }
190}
191```
192
193#### `PTR`
194
195``` js
196{
197 data: 'points.to.another.record'
198}
199```
200
201#### `CNAME`
202
203``` js
204{
205 data: 'cname.to.another.record'
206}
207```
208
209#### `DNAME`
210
211``` js
212{
213 data: 'dname.to.another.record'
214}
215```
216
217#### `CAA`
218
219``` js
220{
221 flags: 128, // octet
222 tag: 'issue|issuewild|iodef',
223 value: 'ca.example.net'
224}
225```
226
227If you need another one, open an issue and we'll try to add it.
228
229## License
230
231MIT
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