bitcoin-net

Bitcoin P2P networking that works in Node and the browser

Usage

npm install bitcoin-net

// import network parameters for Bitcoin
var params = require('webcoin-bitcoin').net

// create peer group
var PeerGroup = require('./').PeerGroup
var peers = new PeerGroup(params)

peers.on('peer', (peer) => {
  console.log('connected to peer', peer.socket.remoteAddress)

  // send/receive messages
  peer.once('pong', () => console.log('received ping response'))
  peer.send('ping', {
    nonce: require('crypto').pseudoRandomBytes(8)
  })
  console.log('sent ping')
})

// create connections to peers
peers.connect()

// allow incoming connections from bitcoin-net peers
peers.accept((err) => {
  if (err) return console.error(err)
  console.log('accepting incoming connections')
})

Table of Contents

• Class: PeerGroup
  • new PeerGroup(params, [opts])
  • peers.connect()
  • peers.accept([port], [cb])
  • peers.addPeer(peer)
  • peer.send(command, payload, [assert])
  • peers.createHeaderStream([opts])
  • peers.createBlockStream(chain, [opts])
  • peers.getBlocks(hashes, [opts], cb)
  • peers.getTransactions(blockHash, txids, [opts], cb)
  • peers.getHeaders(locator, [opts], cb)
  • peers.randomPeer()
  • peers.unaccept([cb])
  • peers.close([cb])
  • peers.peers
  • peers.closed
  • peers.accepting
• Class: Peer
  • new Peer(params, [opts])
  • peer.connect(socket)
  • peer.send(command, payload)
  • peer.ping(cb)
  • peer.getBlocks(hashes, [opts], cb)
  • peer.getTransactions(blockHash, txids, [opts], cb)
  • peer.getHeaders(locator, [opts], cb)
  • peer.disconnect([error])
  • peer.version
  • peer.services
  • peer.socket

PeerGroup

PeerGroup manages connections to multiple peers. It discovers peers through multiple methods: static IPs and DNS seeds provided in the network parameters, and peer-exchange for clients in the browser. PeerGroup also optionally accepts incoming connections via WebSocket and/or WebRTC, to be accessible to browser clients.

var peers = new PeerGroup(params, [opts])

Creates PeerGroup which manages peer connections for a network.

params should be the network parameters for the network you wish to use. Parameters for Bitcoin are available at require('webcoin-bitcoin').net. For more info about params you can use, see the Parameters section.

opts can optionally specify the following:

• numPeers Number (default: 8) - the number of peer connections to maintain
• hardLimit Boolean (default: false) - If false, the number of peers may exceed numPeers when accepting incoming connections. If true then we will drop some random connections to keep the number of peers at numPeers.
• connectWeb Boolean (default: true in browsers, false in Node) - enables making outgoing connections to bitcoin-net WebSocket/WebRTC peers
• connectTimeout Number (default: 5000) - the amount of time (in milliseconds) before timing out when trying to open a connection
• wrtc Object (default: built-in implementation in browsers, undefined in Node) - a WebRTC implementation for Node.js clients, e.g. the wrtc or electron-webrtc packages
• peerOpts Object (default: {}) - The options object to pass to the Peer constructor.

peers.connect()

Begins making outgoing connections. Peers are discovered by choosing a random peer discovery method (static IPs and DNS seeds provided in the network parameters for standard TCP network peers, and peer-exchange for bitcoin-net WebSocket/WebRTC peers).

The PeerGroup will connect to 8 peers by default (overridable via the numPeers option in the constructor). When a connection ends, a new one will be automatically created with a different peer to maintain the number of connections.

Whenever a connection is established, the new Peer will be emitted via the peer event.

peers.accept([port], [cb])

Begins accepting incoming connections via WebSocket and WebRTC. Note that in Node.js WebRTC is only used if the wrtc option was specified in the constructor.

port is the port the WebSocket server will listen on. If not provided, it will default to the defaultWebPort property in the network parameters (and if that is not set, it will default to 8192).

If provided, cb will be called with cb(err) when the PeerGroup begins listening or encounters an error while setting up the server.

For more information about the protocol for incoming connections, see the peer-exchange module.

peers.addPeer(peer)

Manually add an already connected Peer to the PeerGroup. This can be useful if you would like to make a peer connection through your own transport, but have it be managed by the PeerGroup. This method will error if the Peer has not already finished its handshake (e.g. it hasn't emitted the ready event).

peers.send(command, payload, [assert])

Sends a message to all peers in the PeerGroup. See the bitcoin-protocol reference for a list of commands and message formats.

An error will thrown if there are no peers connected, unless assert is false (it defaults to true).

peers.createHeaderStream([opts])

Returns a new HeaderStream, which is a readable stream that emits blockchain headers downloaded from peers in the PeerGroup.

The opts object is passed to the HeaderStream constructor.

peers.createBlockStream(chain, [opts])

Returns a new BlockStream, which is a readable stream that emits full or Bloom filtered blockchain blocks downloaded from peers in the PeerGroup.

chain should be an instance of Blockchain, as provided by the blockchain-spv module.

The opts object is passed to the BlockStream constructor.

peers.getBlocks(hashes, [opts], cb)

Downloads a set of blocks from one of the peers in the PeerGroup. If the peer times out, the request will be retried with a different peer.

hashes should be an array of hashes of the blocks to download (as Buffers).

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request. If it times out, the request will be retried with a different peer.
• filtered Boolean (default: false) - Whether or not to request Bloom filtered Merkle-blocks, or full blocks

cb will be called with cb(err, blocks) once all of the requested blocks have been received or an error occurs.

peers.getTransactions(blockHash, txids, [opts], cb)

Downloads a set of transactions from one of the peers in the PeerGroup. Note that due to the design of Bitcoin full nodes, the requested transactions must all be in the same block and the block hash must be specified. Returned transactions are instances of Transaction from the bitcoinjs-lib module.

blockHash should be the hash of the block containing the transactions (as a Buffer).

txids should be an array of Buffers representing the hashes of the transactions to be downloaded.

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request. If it times out, the request will be retried with a different peer.

cb will be called with cb(err, transactions) once all of the requested blocks have been received or an error occurs.

peers.getHeaders(locator, [opts], cb)

Downloads blockchain headers from a peer in the PeerGroup. Returns up to 2000 contiguous block headers, in order. Returned headers are instances of Block from the bitcoinjs-lib module.

locator should be an array of one or more block hashes (as Buffers), ordered descending by height, representing the starting point for the headers that will be sent. For more information about this, see the bitcoin wiki.

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request. If it times out, the request will be retried with a different peer.
• stop Buffer - If provided, no headers will be sent that come after the header with this hash

cb will be called with cb(err, headers) once all of the requested blocks have been received or an error occurs.

peers.randomPeer()

A helper function which returns a random peer from the PeerGroup. If there are no connected peers, this method will throw an error.

peers.unaccept([cb])

Stops accepting incoming connections. If provided, cb is called with cb(err) when listening has stopped.

peers.close([cb])

Disconnects from all peers and stops accepting incoming connections. If provided, cb is called with cb(err) when all peer connections have ended and listening has stopped.

peers.peers

An array containing the currently connected Peers. Modifying this will cause undefined behavior.

peers.closed

A boolean which is true if peers.close() has been called.

peers.accepting

A boolean which is true if the PeerGroup is accepting incoming connections.

Peer

Peer represents a connection to another node.

Received messages are parsed as JS objects (see bitcoin-protocol for the message formats) and emitted as events (e.g. peer.on('inv', handler) for inv messages). Some basic protocol logic is handled automatically (namely the initial handshake and sending/responding to ping messages).

var peer = new Peer(params, [opts])

params should be the network parameters for the network you wish to use. Parameters for Bitcoin are available at require('webcoin-bitcoin').net. For more info about params you can use, see the Parameters section.

opts can specify the following:

• getTip Function - Should return a Number representing the node's blockchain height. This will get sent in the initial handshake for peer connections. Note that things will work fine even if this isn't provided.
• relay Boolean (default: true) - if false then the remote node will not relay transactions (unless a Bloom filter is set)
• requireBloom Boolean (default: true) - error if the peer does not support Bloom filtering
• userAgent String (default: /<node or browser>:<version>/bitcoin-net:<version>/) - sent in the handshake. See BIP 14 for the proper user agent format.
• subUserAgent String - like the userAgent option, but gets appended to the default user agent string rather than overriding it
• handshakeTimeout Number (default: 8000) - the amount of time (in milliseconds) to wait before timing out when doing the initial handshake
• pingInterval Number (default: 15000) - the amount of time (in milliseconds) between pings sent to the remote peer (used to ensure it is responsive and to measure latency)
• socket duplex stream - the peer connection (equivalent to calling peer.connect(socket))

peer.connect(socket)

Begins communication with the remote peer over socket. The handshake will start after calling this, and the ready event will be emitted once it is complete.

socket should be a duplex stream.

peer.send(command, payload)

Sends a message to the remote peer. See the bitcoin-protocol reference for a list of commands and message formats.

peer.ping(cb)

Sends a ping message to the peer and calls the callback once a pong message is received.

cb will be called with cb(err, latency).

peer.getBlocks(hashes, [opts], cb)

Downloads a set of blocks from the remote peer.

hashes should be an array of hashes of the blocks to download (as Buffers).

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request
• filtered Boolean (default: false) - Whether or not to request Bloom filtered Merkle-blocks, or full blocks

cb will be called with cb(err, blocks) once all of the requested blocks have been received or an error occurs.

peer.getTransactions(blockHash, txids, [opts], cb)

Downloads a set of transactions from the remote peer. Note that due to the design of Bitcoin full nodes, the requested transactions must all be in the same block and the block hash must be specified. Returned transactions are instances of Transaction from the bitcoinjs-lib module.

blockHash should be the hash of the block containing the transactions (as a Buffer).

txids should be an array of Buffers representing the hashes of the transactions to be downloaded.

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request

cb will be called with cb(err, transactions) once all of the requested blocks have been received or an error occurs.

peer.getHeaders(locator, [opts], cb)

Downloads blockchain headers from the remote peer. Returns up to 2000 contiguous block headers, in order. Returned headers are instances of Block from the bitcoinjs-lib module.

locator should be an array of one or more block hashes (as Buffers), ordered descending by height, representing the starting point for the headers that will be sent. For more information about this, see the bitcoin wiki.

opts may contain the following:

• timeout Number (default: peer.latency * 10) - Amount of time (in milliseconds) to wait before timing out on the request
• stop Buffer - If provided, no headers will be sent that come after the header with this hash

cb will be called with cb(err, headers) once all of the requested blocks have been received or the request times out.

peer.disconnect([error])

Disconnects the peer and its underlying socket. The disconnect event will be emitted once the peer has disconnected.

error may be an Error that describes why the peer is being disconnected (emitted as an argument to listeners of the disconnect event).

peer.version

The version message received from the remote peer during the initial handshake.

peer.services

The node services supported by the remote peer, as an array of strings (containing service strings such as 'NODE_NETWORK', 'NODE_BLOOM').

peer.socket

The underlying duplex stream used to communicate with the remote peer.

Parameters

Parameters specify constants for cryptocurrency networks. Parameters should contain the following:

{
  // REQUIRED

  // the fixed value which is used as a prefix to each packet, used to ensure
  // peers are on the same network.
  // (in Bitcoin, this is 0xd9b4bef9)
  magic: Number,

  // the default port this network uses to listen for TCP connections
  // (in Bitcoin, this is 8333)
  defaultPort: Number,

  // OPTIONAL

  // the default port to listen on for WebSocket servers. If not provided,
  // default will be 8192
  defaultWebPort: Number,

  // an array of `bitcoin-net` nodes which are accepting incoming WebSocket
  // connections, used to bootstrap the WebSocket/WebRTC peer exchange. If no
  // web seeds are provided, browser clients will not be able to make any
  // connections
  webSeeds: [
    String, // the hostname of a seed, and optionally the port, in the following format:
            // 'hostname' or 'hostname:port'
    ...
  ],

  // an array of DNS seeds which will be used to discover TCP peers
  dnsSeeds: [
    String, // the hostname of a DNS seed, e.g. 'seed.bitcoin.sipa.be'
    ...
  ],

  // an array of known TCP peers that can be connected to when making outgoing connections
  staticPeers: [
    String, // the hostname of a peer, and optionally the port, in the following format:
            // 'hostname' or 'hostname:port'
    ...
  ]
}

For some examples, see these parameter repos:

• webcoin-bitcoin
• webcoin-bitcoin-testnet
• webcoin-zcash-alpha