Package Exports

dns-packet
dns-packet/rcodes
dns-packet/types

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (dns-packet) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

dns-packet

An abstract-encoding compliant module for encoding / decoding DNS packets. Lifted out of multicast-dns as a separate module.

npm install dns-packet

Usage

var packet = require('dns-packet')
var dgram = require('dgram')

var socket = dgram.createSocket('udp4')

var buf = packet.encode({
  type: 'query',
  id: 1,
  flags: packet.RECURSION_DESIRED,
  questions: [{
    type: 'A',
    class: 'IN',
    name: 'google.com'
  }]
})

socket.on('message', function (message) {
  console.log(packet.decode(message)) // prints out a response from google dns
})

socket.send(buf, 0, buf.length, 53, '8.8.8.8')

API

`var buf = packets.encode(packet, [buf], [offset])`

Encodes a DNS packet into a buffer.

`var packet = packets.decode(buf, [offset])`

Decode a DNS packet from a buffer

`var len = packets.encodingLength(packet)`

Returns how many bytes are needed to encode the DNS packet

Packets

Packets look like this

{
  type: 'query|response',
  id: optionalIdNumber,
  flags: optionalBitFlags,
  questions: [...],
  answers: [...],
  additionals: [...],
  authorities: [...]
}

The bit flags available are

packet.RECURSION_DESIRED
packet.RECURSION_AVAILABLE
packet.TRUNCATED_RESPONSE
packet.AUTHORITATIVE_ANSWER
packet.AUTHENTIC_DATA
packet.CHECKING_DISABLED

To use more than one flag bitwise-or them together

var flags = packet.RECURSION_DESIRED | packet.RECURSION_AVAILABLE

And to check for a flag use bitwise-and

var isRecursive = message.flags & packet.RECURSION_DESIRED

A question looks like this

{
  type: 'A', // or SRV, AAAA, etc
  class: 'IN', // one of IN, CS, CH, HS, ANY. Default: IN
  name: 'google.com' // which record are you looking for
}

And an answers, additional, or authority looks like this

{
  type: 'A', // or SRV, AAAA, etc
  class: 'IN', // one of IN, CS, CH, HS
  name: 'google.com', // which name is this record for
  ttl: optionalTimeToLiveInSeconds,
  (record specific data, see below)
}

Currently the different available records are

`A`

{
  data: 'IPv4 address' // fx 127.0.0.1
}

`AAAA`

{
  data: 'IPv6 address' // fx fe80::1
}

`TXT`

{
  data: Buffer('some text')
}

`NS`

{
  data: nameServer
}

`NULL`

{
  data: Buffer('any binary data')
}

`SOA`

{
  data:
    {
      mname: domainName,
      rname: mailbox,
      serial: zoneSerial,
      refresh: refreshInterval,
      retry: retryInterval,
      expire: expireInterval,
      minimum: minimumTTL
    }
}

`SRV`

{
  data: {
    port: servicePort,
    target: serviceHostName,
    priority: optionalServicePriority,
    weight: optionalServiceWeight
  }
}

`HINFO`

{
  data: {
    cpu: 'cpu info',
    os: 'os info'
  }
}

`PTR`

{
  data: 'points.to.another.record'
}

`CNAME`

{
  data: 'cname.to.another.record'
}

`DNAME`

{
  data: 'dname.to.another.record'
}

`CAA`

{
  flags: 128, // octet
  tag: 'issue|issuewild|iodef',
  value: 'ca.example.net'
}

If you need another one, open an issue and we'll try to add it.

License

MIT