mirror of
https://github.com/webtorrent/bittorrent-tracker.git
synced 2024-12-14 11:26:25 +00:00
354 lines
9.6 KiB
JavaScript
354 lines
9.6 KiB
JavaScript
module.exports = WebSocketTracker
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var debug = require('debug')('bittorrent-tracker:websocket-tracker')
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var extend = require('xtend')
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var hat = require('hat')
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var inherits = require('inherits')
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var Peer = require('simple-peer')
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var Socket = require('simple-websocket')
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var common = require('../common')
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var Tracker = require('./tracker')
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// Use a socket pool, so tracker clients share WebSocket objects for the same server.
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// In practice, WebSockets are pretty slow to establish, so this gives a nice performance
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// boost, and saves browser resources.
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var socketPool = {}
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var RECONNECT_MINIMUM = 15 * 1000
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var RECONNECT_MAXIMUM = 30 * 60 * 1000
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var RECONNECT_VARIANCE = 30 * 1000
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var OFFER_TIMEOUT = 50 * 1000
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inherits(WebSocketTracker, Tracker)
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function WebSocketTracker (client, announceUrl, opts) {
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var self = this
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Tracker.call(self, client, announceUrl)
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debug('new websocket tracker %s', announceUrl)
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self.peers = {} // peers (offer id -> peer)
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self.socket = null
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self.reconnecting = false
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self.retries = 0
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self._openSocket()
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}
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WebSocketTracker.prototype.DEFAULT_ANNOUNCE_INTERVAL = 30 * 1000 // 30 seconds
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WebSocketTracker.prototype.announce = function (opts) {
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var self = this
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if (self.destroyed || self.reconnecting) return
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if (!self.socket.connected) {
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return self.socket.once('connect', self.announce.bind(self, opts))
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}
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// Limit the number of offers that are generated, since it can be slow
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var numwant = Math.min(opts.numwant, 10)
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self._generateOffers(numwant, function (offers) {
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var params = extend(opts, {
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action: 'announce',
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numwant: numwant,
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info_hash: self.client._infoHashBinary,
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peer_id: self.client._peerIdBinary,
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offers: offers
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})
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if (self._trackerId) params.trackerid = self._trackerId
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self._send(params)
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})
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}
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WebSocketTracker.prototype.scrape = function (opts) {
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var self = this
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if (self.destroyed || self.reconnecting) return
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if (!self.socket.connected) {
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return self.socket.once('connect', self.scrape.bind(self, opts))
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}
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var infoHashes = (Array.isArray(opts.infoHash) && opts.infoHash.length > 0)
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? opts.infoHash.map(function (infoHash) {
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return infoHash.toString('binary')
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})
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: (opts.infoHash && opts.infoHash.toString('binary')) || self.client._infoHashBinary
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var params = {
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action: 'scrape',
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info_hash: infoHashes
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}
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self._send(params)
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}
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WebSocketTracker.prototype.destroy = function (cb) {
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var self = this
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if (!cb) cb = noop
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if (self.destroyed) return cb(null)
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self.destroyed = true
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clearInterval(self.interval)
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delete socketPool[self.announceUrl]
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self.socket.removeListener('connect', self._onSocketConnectBound)
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self.socket.removeListener('data', self._onSocketDataBound)
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self.socket.removeListener('close', self._onSocketCloseBound)
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self.socket.removeListener('error', self._onSocketErrorBound)
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self._onSocketConnectBound = null
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self._onSocketErrorBound = null
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self._onSocketDataBound = null
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self._onSocketCloseBound = null
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self.socket.on('error', noop) // ignore all future errors
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try {
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self.socket.destroy(cb)
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} catch (err) {
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cb(null)
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}
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self.socket = null
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}
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WebSocketTracker.prototype._openSocket = function () {
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var self = this
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self.destroyed = false
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self._onSocketConnectBound = self._onSocketConnect.bind(self)
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self._onSocketErrorBound = self._onSocketError.bind(self)
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self._onSocketDataBound = self._onSocketData.bind(self)
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self._onSocketCloseBound = self._onSocketClose.bind(self)
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self.socket = socketPool[self.announceUrl]
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if (!self.socket) {
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self.socket = socketPool[self.announceUrl] = new Socket(self.announceUrl)
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self.socket.on('connect', self._onSocketConnectBound)
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}
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self.socket.on('data', self._onSocketDataBound)
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self.socket.on('close', self._onSocketCloseBound)
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self.socket.on('error', self._onSocketErrorBound)
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}
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WebSocketTracker.prototype._onSocketConnect = function () {
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var self = this
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if (self.destroyed) return
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if (self.reconnecting) {
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self.reconnecting = false
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self.retries = 0
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self.announce(self.client._defaultAnnounceOpts())
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}
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}
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WebSocketTracker.prototype._onSocketData = function (data) {
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var self = this
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if (self.destroyed) return
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try {
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data = JSON.parse(data)
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} catch (err) {
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self.client.emit('warning', new Error('Invalid tracker response'))
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return
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}
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if (data.action === 'announce' || data.offer || data.answer) {
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self._onAnnounceResponse(data)
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} else if (data.action === 'scrape') {
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self._onScrapeResponse(data)
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} else {
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self._onSocketError(new Error('invalid action in WS response: ' + data.action))
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}
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}
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WebSocketTracker.prototype._onAnnounceResponse = function (data) {
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var self = this
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if (data.info_hash !== self.client._infoHashBinary) {
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debug(
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'ignoring websocket data from %s for %s (looking for %s: reused socket)',
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self.announceUrl, common.binaryToHex(data.info_hash), self.client.infoHash
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)
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return
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}
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if (data.peer_id && data.peer_id === self.client._peerIdBinary) {
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// ignore offers/answers from this client
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return
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}
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debug(
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'received %s from %s for %s',
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JSON.stringify(data), self.announceUrl, self.client.infoHash
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)
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var failure = data['failure reason']
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if (failure) return self.client.emit('warning', new Error(failure))
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var warning = data['warning message']
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if (warning) self.client.emit('warning', new Error(warning))
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var interval = data.interval || data['min interval']
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if (interval) self.setInterval(interval * 1000)
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var trackerId = data['tracker id']
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if (trackerId) {
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// If absent, do not discard previous trackerId value
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self._trackerId = trackerId
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}
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if (data.complete != null) {
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self.client.emit('update', {
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announce: self.announceUrl,
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complete: data.complete,
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incomplete: data.incomplete
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})
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}
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var peer
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if (data.offer && data.peer_id) {
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debug('creating peer (from remote offer)')
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peer = new Peer({
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trickle: false,
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config: self.client._rtcConfig,
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wrtc: self.client._wrtc
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})
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peer.id = common.binaryToHex(data.peer_id)
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peer.once('signal', function (answer) {
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var params = {
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info_hash: self.client._infoHashBinary,
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peer_id: self.client._peerIdBinary,
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to_peer_id: data.peer_id,
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answer: answer,
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offer_id: data.offer_id
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}
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if (self._trackerId) params.trackerid = self._trackerId
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self._send(params)
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})
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peer.signal(data.offer)
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self.client.emit('peer', peer)
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}
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if (data.answer && data.peer_id) {
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var offerId = common.binaryToHex(data.offer_id)
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peer = self.peers[offerId]
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if (peer) {
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peer.id = common.binaryToHex(data.peer_id)
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peer.signal(data.answer)
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self.client.emit('peer', peer)
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clearTimeout(peer.trackerTimeout)
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peer.trackerTimeout = null
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delete self.peers[offerId]
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} else {
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debug('got unexpected answer: ' + JSON.stringify(data.answer))
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}
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}
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}
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WebSocketTracker.prototype._onScrapeResponse = function (data) {
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var self = this
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data = data.files || {}
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var keys = Object.keys(data)
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if (keys.length === 0) {
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self.client.emit('warning', new Error('invalid scrape response'))
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return
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}
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keys.forEach(function (infoHash) {
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var response = data[infoHash]
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// TODO: optionally handle data.flags.min_request_interval
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// (separate from announce interval)
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self.client.emit('scrape', {
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announce: self.announceUrl,
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infoHash: common.binaryToHex(infoHash),
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complete: response.complete,
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incomplete: response.incomplete,
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downloaded: response.downloaded
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})
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})
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}
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WebSocketTracker.prototype._onSocketClose = function () {
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var self = this
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if (self.destroyed) return
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self.destroy()
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self._startReconnectTimer()
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}
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WebSocketTracker.prototype._onSocketError = function (err) {
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var self = this
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if (self.destroyed) return
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self.destroy()
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// errors will often happen if a tracker is offline, so don't treat it as fatal
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self.client.emit('warning', err)
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self._startReconnectTimer()
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}
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WebSocketTracker.prototype._startReconnectTimer = function () {
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var self = this
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var ms = Math.floor(Math.random() * RECONNECT_VARIANCE) + Math.min(Math.pow(2, self.retries) * RECONNECT_MINIMUM, RECONNECT_MAXIMUM)
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self.reconnecting = true
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var reconnectTimer = setTimeout(function () {
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self.retries++
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self._openSocket()
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}, ms)
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if (reconnectTimer.unref) reconnectTimer.unref()
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debug('reconnecting socket in %s ms', ms)
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}
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WebSocketTracker.prototype._send = function (params) {
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var self = this
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if (self.destroyed) return
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var message = JSON.stringify(params)
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debug('send %s', message)
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self.socket.send(message)
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}
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WebSocketTracker.prototype._generateOffers = function (numwant, cb) {
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var self = this
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var offers = []
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debug('generating %s offers', numwant)
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for (var i = 0; i < numwant; ++i) {
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generateOffer()
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}
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function generateOffer () {
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var offerId = hat(160)
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debug('creating peer (from _generateOffers)')
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var peer = self.peers[offerId] = new Peer({
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initiator: true,
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trickle: false,
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config: self.client._rtcConfig,
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wrtc: self.client._wrtc
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})
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peer.once('signal', function (offer) {
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offers.push({
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offer: offer,
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offer_id: common.hexToBinary(offerId)
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})
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checkDone()
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})
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peer.trackerTimeout = setTimeout(function () {
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debug('tracker timeout: destroying peer')
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peer.trackerTimeout = null
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delete self.peers[offerId]
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peer.destroy()
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}, OFFER_TIMEOUT)
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}
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function checkDone () {
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if (offers.length === numwant) {
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debug('generated %s offers', numwant)
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cb(offers)
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}
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}
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}
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function noop () {}
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