polis-protocol

Polis network protocol streams

This module encodes and decodes low-level network protocol data using streams.

Usage

npm install polis-protocol

var net = require('net')
var bp = require('polis-protocol')

var decoder = bp.createDecodeStream()
decoder.on('data', function (message) { console.log(message) })

var encoder = bp.createEncodeStream()

var socket = net.connect(8333, '127.0.0.1')
socket.pipe(decoder)
encoder.pipe(socket)

encoder.write({
  magic: 0xd9b4bef9,
  command: 'ping',
  payload: {
    nonce: new Buffer('0123456789abcdef', 'hex')
  }
})

Methods

createDecodeStream([opts])

Creates a stream which parses raw network bytes written to it and outputs message objects.

Opts may contain:

{
  magic: Number
  // If provided, the decoder will check if messages' "magic" field matches
  // this value. If it does not match, the stream will emit an error.
}

createEncodeStream([opts])

Creates a stream which encodes message objects to raw network bytes.

Opts may contain:

{
  magic: Number
  // If provided, the encoder will automatically add the "magic" field to each
  // message written to it.
}

Format

Decoder

Emitted by the decoder:

{
  magic: Number,
  command: String,
  length: Number,
  checksum: Buffer, // 8 bytes,
  payload: Object // see below for detailed payload formats
}

Encoder

Written to the encoder:

{
  magic: Number, // optional if you set this in the options
  command: String,
  payload: Object // see below for detailed payload formats
}

Payload Reference

The formats for the objects used as message payloads for the various commands are as follows. See the wiki for more information about these messages.

version

{
  version: Number,
  services: Buffer, // 8 bytes
  timestamp: Number,
  receiverAddress: {
    services: Buffer, // 8 bytes
    address: String, // ipv4 or ipv6
    port: Number
  },
  senderAddress: {
    services: Buffer, // 8 bytes
    address: String, // ipv4 or ipv6
    port: Number
  },
  nonce: Buffer, // 8 bytes
  userAgent: String,
  startHeight: Number,
  relay: Boolean
}

verack, getaddr, mempool, filterclear, sendheaders

// no payload needed

addr

[
  {
    time: Number,
    services: Buffer, // 8 bytes
    address: String, // ipv4 or ipv6
    port: Number
  },
  ...
]

inv, getdata, notfound

[
  {
    type: Number,
    hash: Buffer // 32 bytes
  },
  ...
]

getblocks, getheaders

{
  version: Number,
  locator: [
    Buffer // 32 bytes
  ],
  hashStop: Buffer // 32 bytes
}

tx

{
  version: Number,
  ins: [
    {
      hash: Buffer, // 32 bytes
      index: Number,
      script: Buffer, // varying length
      sequence: Number
    },
    ...
  ],
  outs: [
    {
      value: BN, // from 'bn.js' package
      script: Buffer // varying length
    },
    ...
  ],
  locktime: Number
}

block

{
  header: {
    version: Number,
    prevHash: Buffer, // 32 bytes
    merkleRoot: Buffer, // 32 bytes
    timestamp: Number,
    bits: Number,
    nonce: Number,
  },
  transactions: [
    {}, // same format as 'tx' message
    ...
  ]
}

headers

[
  {
    header: {
      version: Number,
      prevHash: Buffer, // 32 bytes
      merkleRoot: Buffer, // 32 bytes
      timestamp: Number,
      bits: Number,
      nonce: Number,
    },
    nTransactions: Number
  },
  ...
]

ping, pong

{
  nonce: Buffer // 8 bytes
}

reject

{
  message: String,
  ccode: Number,
  reason: String,
  data: Buffer // varying length
}

filterload

{
  data: Buffer, // varying length
  nHashFuncs: Number,
  nTweak: Number,
  nFlags: Number
}

filteradd

{
  data: Buffer // varying length
}

merkleblock

{
  header: {
    version: Number,
    prevHash: Buffer, // 32 bytes
    merkleRoot: Buffer, // 32 bytes
    timestamp: Number,
    bits: Number,
    nonce: Number
  },
  numTransactions: Number,
  hashes: [
    Buffer // 32 bytes
  ],
  flags: Buffer // varying length
}

alert

{
  payload: Buffer, // varying length
  signature: Buffer // varying length
}