bittorrent-tracker/lib/websocket-tracker.js

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// TODO: destroy the websocket
module.exports = WebSocketTracker
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var debug = require('debug')('bittorrent-tracker:websocket-tracker')
var EventEmitter = require('events').EventEmitter
var hat = require('hat')
var inherits = require('inherits')
var Peer = require('simple-peer')
var Socket = require('simple-websocket')
var common = require('./common')
// It turns out that you can't open multiple websockets to the same server within one
// browser tab, so let's reuse them.
var socketPool = {}
inherits(WebSocketTracker, EventEmitter)
function WebSocketTracker (client, announceUrl, opts) {
var self = this
EventEmitter.call(self)
debug('new websocket tracker %s', announceUrl)
self.client = client
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self._opts = opts
self._announceUrl = announceUrl
self._peers = {} // peers (offer id -> peer)
self._ready = false
self._socket = null
self._intervalMs = self.client._intervalMs // use client interval initially
self._interval = null
if (socketPool[announceUrl]) self._socket = socketPool[announceUrl]
else self._socket = socketPool[announceUrl] = new Socket(announceUrl)
self._socket.on('warning', self._onSocketWarning.bind(self))
self._socket.on('error', self._onSocketWarning.bind(self)) // TODO: handle error
self._socket.on('message', self._onSocketMessage.bind(self))
}
WebSocketTracker.prototype.announce = function (opts) {
var self = this
if (!self._socket.ready) return self._socket.on('ready', self.announce.bind(self, opts))
opts.info_hash = self.client._infoHash.toString('binary')
opts.peer_id = self.client._peerId.toString('binary')
self._generateOffers(opts.numWant, function (offers) {
opts.offers = offers
if (self._trackerId) {
opts.trackerid = self._trackerId
}
self._send(opts)
})
}
WebSocketTracker.prototype.scrape = function (opts) {
var self = this
self.client.emit('error', new Error('scrape not supported ' + self._announceUrl))
return
}
// TODO: Improve this interface
WebSocketTracker.prototype.setInterval = function (intervalMs) {
var self = this
clearInterval(self._interval)
self._intervalMs = intervalMs
if (intervalMs) {
// HACK
var update = self.announce.bind(self, self.client._defaultAnnounceOpts())
self._interval = setInterval(update, self._intervalMs)
}
}
WebSocketTracker.prototype._onSocketWarning = function (err) {
debug('tracker warning %s', err.message)
}
WebSocketTracker.prototype._onSocketMessage = function (data) {
var self = this
if (!(typeof data === 'object' && data !== null)) {
return self.client.emit('warning', new Error('Invalid tracker response'))
}
if (data.info_hash !== self.client._infoHash.toString('binary')) {
return self.client.emit('warning', new Error('Invalid tracker response'))
}
debug('received %s from %s', JSON.stringify(data), self._announceUrl)
var failure = data['failure reason']
if (failure) return self.client.emit('warning', new Error(failure))
var warning = data['warning message']
if (warning) self.client.emit('warning', new Error(warning))
var interval = data.interval || data['min interval']
if (interval && !self._opts.interval && self._intervalMs !== 0) {
// use the interval the tracker recommends, UNLESS the user manually specifies an
// interval they want to use
self.setInterval(interval * 1000)
}
var trackerId = data['tracker id']
if (trackerId) {
// If absent, do not discard previous trackerId value
self._trackerId = trackerId
}
if (data.complete) {
self.client.emit('update', {
announce: self._announceUrl,
complete: data.complete,
incomplete: data.incomplete
})
}
var peer
if (data.offer) {
peer = new Peer({ trickle: false, config: self._opts.rtcConfig })
peer.id = common.binaryToHex(data.peer_id)
peer.once('signal', function (answer) {
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var params = {
info_hash: self.client._infoHash.toString('binary'),
peer_id: self.client._peerId.toString('binary'),
to_peer_id: data.peer_id,
answer: answer,
offer_id: data.offer_id
}
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if (self._trackerId) params.trackerid = self._trackerId
self._send(params)
})
peer.signal(data.offer)
self.client.emit('peer', peer)
}
if (data.answer) {
peer = self._peers[data.offer_id]
if (peer) {
peer.id = common.binaryToHex(data.peer_id)
peer.signal(data.answer)
self.client.emit('peer', peer)
} else {
debug('got unexpected answer: ' + JSON.stringify(data.answer))
}
}
}
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WebSocketTracker.prototype._send = function (params) {
var self = this
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debug('send %s', JSON.stringify(params))
self._socket.send(params)
}
WebSocketTracker.prototype._generateOffers = function (numWant, cb) {
var self = this
var offers = []
debug('generating %s offers', numWant)
// TODO: cleanup dead peers and peers that never get a return offer, from self._peers
for (var i = 0; i < numWant; ++i) {
generateOffer()
}
function generateOffer () {
var offerId = hat(160)
var peer = self._peers[offerId] = new Peer({
initiator: true,
trickle: false,
config: self._opts.rtcConfig
})
peer.once('signal', function (offer) {
offers.push({
offer: offer,
offer_id: offerId
})
checkDone()
})
}
function checkDone () {
if (offers.length === numWant) {
debug('generated %s offers', numWant)
cb(offers)
}
}
}