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const arrayRemove = require('unordered-array-remove')
const debug = require('debug')('webtorrent:peer')
const Wire = require('bittorrent-protocol')
const WebConn = require('./webconn')
const CONNECT_TIMEOUT_TCP = 5000
const CONNECT_TIMEOUT_WEBRTC = 25000
const HANDSHAKE_TIMEOUT = 25000
/**
* WebRTC peer connections start out connected, because WebRTC peers require an
* "introduction" (i.e. WebRTC signaling), and there's no equivalent to an IP address
* that lets you refer to a WebRTC endpoint.
*/
exports.createWebRTCPeer = (conn, swarm) => {
const peer = new Peer(conn.id, 'webrtc')
peer.conn = conn
peer.swarm = swarm
if (peer.conn.connected) {
peer.onConnect()
} else {
peer.conn.once('connect', () => { peer.onConnect() })
peer.conn.once('error', err => { peer.destroy(err) })
peer.startConnectTimeout()
}
return peer
}
/**
* Incoming TCP peers start out connected, because the remote peer connected to the
* listening port of the TCP server. Until the remote peer sends a handshake, we don't
* know what swarm the connection is intended for.
*/
exports.createTCPIncomingPeer = conn => {
const addr = `${conn.remoteAddress}:${conn.remotePort}`
const peer = new Peer(addr, 'tcpIncoming')
peer.conn = conn
peer.addr = addr
peer.onConnect()
return peer
}
/**
* Outgoing TCP peers start out with just an IP address. At some point (when there is an
* available connection), the client can attempt to connect to the address.
*/
exports.createTCPOutgoingPeer = (addr, swarm) => {
const peer = new Peer(addr, 'tcpOutgoing')
peer.addr = addr
peer.swarm = swarm
return peer
}
/**
* Peer that represents a Web Seed (BEP17 / BEP19).
*/
exports.createWebSeedPeer = (url, swarm) => {
const peer = new Peer(url, 'webSeed')
peer.swarm = swarm
peer.conn = new WebConn(url, swarm)
peer.onConnect()
return peer
}
/**
* Peer. Represents a peer in the torrent swarm.
*
* @param {string} id "ip:port" string, peer id (for WebRTC peers), or url (for Web Seeds)
* @param {string} type the type of the peer
*/
class Peer {
constructor (id, type) {
this.id = id
this.type = type
debug('new %s Peer %s', type, id)
this.addr = null
this.conn = null
this.swarm = null
this.wire = null
this.connected = false
this.destroyed = false
this.timeout = null // handshake timeout
this.retries = 0 // outgoing TCP connection retry count
this.sentHandshake = false
}
/**
* Called once the peer is connected (i.e. fired 'connect' event)
* @param {Socket} conn
*/
onConnect () {
if (this.destroyed) return
this.connected = true
debug('Peer %s connected', this.id)
clearTimeout(this.connectTimeout)
const conn = this.conn
conn.once('end', () => {
this.destroy()
})
conn.once('close', () => {
this.destroy()
})
conn.once('finish', () => {
this.destroy()
})
conn.once('error', err => {
this.destroy(err)
})
const wire = this.wire = new Wire()
wire.type = this.type
wire.once('end', () => {
this.destroy()
})
wire.once('close', () => {
this.destroy()
})
wire.once('finish', () => {
this.destroy()
})
wire.once('error', err => {
this.destroy(err)
})
wire.once('handshake', (infoHash, peerId) => {
this.onHandshake(infoHash, peerId)
})
this.startHandshakeTimeout()
conn.pipe(wire).pipe(conn)
if (this.swarm && !this.sentHandshake) this.handshake()
}
/**
* Called when handshake is received from remote peer.
* @param {string} infoHash
* @param {string} peerId
*/
onHandshake (infoHash, peerId) {
if (!this.swarm) return // `this.swarm` not set yet, so do nothing
if (this.destroyed) return
if (this.swarm.destroyed) {
return this.destroy(new Error('swarm already destroyed'))
}
if (infoHash !== this.swarm.infoHash) {
return this.destroy(new Error('unexpected handshake info hash for this swarm'))
}
if (peerId === this.swarm.peerId) {
return this.destroy(new Error('refusing to connect to ourselves'))
}
debug('Peer %s got handshake %s', this.id, infoHash)
clearTimeout(this.handshakeTimeout)
this.retries = 0
let addr = this.addr
if (!addr && this.conn.remoteAddress && this.conn.remotePort) {
addr = `${this.conn.remoteAddress}:${this.conn.remotePort}`
}
this.swarm._onWire(this.wire, addr)
// swarm could be destroyed in user's 'wire' event handler
if (!this.swarm || this.swarm.destroyed) return
if (!this.sentHandshake) this.handshake()
}
handshake () {
const opts = {
dht: this.swarm.private ? false : !!this.swarm.client.dht
}
this.wire.handshake(this.swarm.infoHash, this.swarm.client.peerId, opts)
this.sentHandshake = true
}
startConnectTimeout () {
clearTimeout(this.connectTimeout)
this.connectTimeout = setTimeout(() => {
this.destroy(new Error('connect timeout'))
}, this.type === 'webrtc' ? CONNECT_TIMEOUT_WEBRTC : CONNECT_TIMEOUT_TCP)
if (this.connectTimeout.unref) this.connectTimeout.unref()
}
startHandshakeTimeout () {
clearTimeout(this.handshakeTimeout)
this.handshakeTimeout = setTimeout(() => {
this.destroy(new Error('handshake timeout'))
}, HANDSHAKE_TIMEOUT)
if (this.handshakeTimeout.unref) this.handshakeTimeout.unref()
}
destroy (err) {
if (this.destroyed) return
this.destroyed = true
this.connected = false
debug('destroy %s (error: %s)', this.id, err && (err.message || err))
clearTimeout(this.connectTimeout)
clearTimeout(this.handshakeTimeout)
const swarm = this.swarm
const conn = this.conn
const wire = this.wire
this.swarm = null
this.conn = null
this.wire = null
if (swarm && wire) {
arrayRemove(swarm.wires, swarm.wires.indexOf(wire))
}
if (conn) {
conn.on('error', () => {})
conn.destroy()
}
if (wire) wire.destroy()
if (swarm) swarm.removePeer(this.id)
}
}
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