@leichtgewicht/dns-socket

dns-socket

Make low-level DNS requests with retry and timeout support.

npm install @leichtgewicht/dns-socket

Usage

import { DNSSocket } from '@leichtgewicht/dns-socket'
const socket = new DNSSocket()

socket.query({
  questions: [{
    type: 'A',
    name: 'google.com'
  }]
}, 53, '8.8.8.8', (err, res) => {
  console.log(err, res) // prints the A record for google.com
})

API

var socket = new DNSSocket([options])

Create a new DNS socket instance. The options object includes:

• retries Number: Number of total query attempts made during timeout. Default: 5.
• socket Object: A custom dgram socket. Default: A 'udp4' socket.
• timeout Number: Total timeout in milliseconds after which a 'timeout' event is emitted. Default: 7500.
• maxQueries Number: Each request has an id, this is stored as static sized array. maxQueries is the size of this array, limiting the max number of inflight requests. Default: 10000.
• maxRedirects Number: If you query for a single A record and get back CNAME, the lib will try to follow the chain and resolve the CNAME to A. The maximum number of steps is defined by the maxRedirects. Default: 0
• timeoutChecks Number: Timeouts are checked each timeoutChecks ms, for large number of parallel request, you might want to increase this number. Default: timeout / 10

socket.on('query', query, port, host)

Emitted when a dns query is received. The query is a dns-packet

socket.on('response', response, port, host)

Emitted when a dns response is received. The response is a dns-packet

var id = socket.query(query, port, [host], [callback])

Send a dns query. If host is omitted it defaults to 127.0.0.1. When the remote replies the callback is called with (err, response, query) and an response is emitted as well. If the query times out the callback is called with an error. The host parameter can be an array, during resolve the lib will randomly select one host.

Returns the query id

socket.response(query, response, port, [host])

Send a response to a query.

socket.cancel(id)

Cancel a query

socket.bind([port][, address][, onlistening])

socket.bind(options, [onlistening])

Bind the underlying udp socket to a specific port. Takes the same arguments as socket#bind.

socket.destroy([onclose])

Destroy the socket.

socket.inflight

Number of inflight queries.

License

MIT