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ferossfeross
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Merge pull request webtorrent#45 from feross/refactor
Refactor the server-side code
2 parents 28189a0 + c97e423 commit 20cb182

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7 files changed

+435
-370
lines changed

7 files changed

+435
-370
lines changed

‎lib/common.js‎

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var querystring = require('querystring')
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exports.NUM_ANNOUNCE_PEERS = 50
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exports.MAX_ANNOUNCE_PEERS = 82
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exports.CONNECTION_ID = Buffer.concat([ toUInt32(0x417), toUInt32(0x27101980) ])
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exports.ACTIONS = { CONNECT: 0, ANNOUNCE: 1, SCRAPE: 2, ERROR: 3 }
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exports.EVENTS = { update: 0, completed: 1, started: 2, stopped: 3 }
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exports.EVENT_IDS = {
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0: 'update',
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1: 'completed',
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2: 'started',
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3: 'stopped'
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};
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function toUInt32 (n) {
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var buf = new Buffer(4)

‎lib/parse_http.js‎

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var common = require('./common')
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var REMOVE_IPV6_RE = /^::ffff:/
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module.exports = parseHttpRequest
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function parseHttpRequest (req, options) {
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var s = req.url.split('?')
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var params = common.querystringParse(s[1])
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if (s[0] === '/announce') {
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params.action = common.ACTIONS.ANNOUNCE
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params.peer_id = typeof params.peer_id === 'string' && common.binaryToUtf8(params.peer_id)
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params.port = Number(params.port)
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if (typeof params.info_hash !== 'string') throw new Error('invalid info_hash')
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if (params.info_hash.length !== 20) throw new Error('invalid info_hash length')
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if (typeof params.peer_id !== 'string') throw new Error('invalid peer_id')
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if (params.peer_id.length !== 20) throw new Error('invalid peer_id length')
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if (!params.port) throw new Error('invalid port')
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params.left = Number(params.left)
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params.compact = Number(params.compact)
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params.ip = options.trustProxy
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? req.headers['x-forwarded-for'] || req.connection.remoteAddress
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: req.connection.remoteAddress.replace(REMOVE_IPV6_RE, '') // force ipv4
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params.addr = params.ip + ':' + params.port // TODO: ipv6 brackets?
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params.numwant = Math.min(
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Number(params.numwant) || common.NUM_ANNOUNCE_PEERS,
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common.MAX_ANNOUNCE_PEERS
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)
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return params
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} else if (s[0] === '/scrape') { // unofficial scrape message
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params.action = common.ACTIONS.SCRAPE
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if (typeof params.info_hash === 'string') {
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params.info_hash = [ params.info_hash ]
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}
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if (params.info_hash) {
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if (!Array.isArray(params.info_hash)) throw new Error('invalid info_hash array')
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params.info_hash.forEach(function (infoHash) {
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if (infoHash.length !== 20) {
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throw new Error('invalid info_hash')
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}
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})
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}
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return params
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} else {
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return null
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}
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}

‎lib/parse_udp.js‎

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var bufferEqual = require('buffer-equal')
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var ipLib = require('ip')
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var common = require('./common')
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module.exports = parseUdpRequest
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function parseUdpRequest (msg, rinfo) {
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if (msg.length < 16) {
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throw new Error('received packet is too short')
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}
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if (rinfo.family !== 'IPv4') {
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throw new Error('udp tracker does not support IPv6')
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}
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var params = {
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connectionId: msg.slice(0, 8), // 64-bit
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action: msg.readUInt32BE(8),
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transactionId: msg.readUInt32BE(12)
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}
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// TODO: randomize:
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if (!bufferEqual(params.connectionId, common.CONNECTION_ID)) {
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throw new Error('received packet with invalid connection id')
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}
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if (params.action === common.ACTIONS.CONNECT) {
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// No further params
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} else if (params.action === common.ACTIONS.ANNOUNCE) {
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params.info_hash = msg.slice(16, 36).toString('binary') // 20 bytes
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params.peer_id = msg.slice(36, 56).toString('utf8') // 20 bytes
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params.downloaded = fromUInt64(msg.slice(56, 64)) // TODO: track this?
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params.left = fromUInt64(msg.slice(64, 72))
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params.uploaded = fromUInt64(msg.slice(72, 80)) // TODO: track this?
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params.event = msg.readUInt32BE(80)
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params.event = common.EVENT_IDS[params.event]
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if (!params.event) throw new Error('invalid event') // early return
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params.ip = msg.readUInt32BE(84) // optional
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params.ip = params.ip ?
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ipLib.toString(params.ip) :
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rinfo.address
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params.key = msg.readUInt32BE(88) // TODO: what is this for?
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params.numwant = msg.readUInt32BE(92) // optional
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// never send more than MAX_ANNOUNCE_PEERS or else the UDP packet will get bigger than
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// 512 bytes which is not safe
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params.numwant = Math.min(params.numwant || common.NUM_ANNOUNCE_PEERS, common.MAX_ANNOUNCE_PEERS)
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params.port = msg.readUInt16BE(96) || rinfo.port // optional
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params.addr = params.ip + ':' + params.port // TODO: ipv6 brackets
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params.compact = 1 // udp is always compact
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} else if (params.action === common.ACTIONS.SCRAPE) { // scrape message
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params.info_hash = msg.slice(16, 36).toString('binary') // 20 bytes
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// TODO: support multiple info_hash scrape
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if (msg.length > 36) {
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throw new Error('multiple info_hash scrape not supported')
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}
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} else {
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throw new Error('Invalid action in UDP packet: ' + params.action)
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}
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return params
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}
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// HELPER FUNCTIONS
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var TWO_PWR_32 = (1 << 16) * 2
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/**
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* Return the closest floating-point representation to the buffer value. Precision will be
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* lost for big numbers.
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*/
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function fromUInt64 (buf) {
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var high = buf.readUInt32BE(0) | 0 // force
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var low = buf.readUInt32BE(4) | 0
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var lowUnsigned = (low >= 0) ? low : TWO_PWR_32 + low
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return high * TWO_PWR_32 + lowUnsigned
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}

‎lib/swarm.js‎

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var debug = require('debug')('bittorrent-tracker')
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module.exports = Swarm
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// Regard this as the default implementation of an interface that you
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// need to support when overriding Server.getSwarm()
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function Swarm (infoHash, server) {
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this.peers = {}
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this.complete = 0
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this.incomplete = 0
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this.emit = server.emit.bind(server)
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}
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Swarm.prototype.announce = function (params, cb) {
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var self = this
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var peer = self.peers[params.addr]
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// Dispatch announce event
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if (!params.event || params.event === 'empty') params.event = 'update'
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var fn = '_onAnnounce_' + params.event
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if (self[fn]) {
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self[fn](params, peer, function (err) {
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// event processed, prepare response:
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if (params.left === 0 && peer) peer.complete = true
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// send peers
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var peers = self._getPeers(params.numwant)
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cb(null, {
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complete: self.complete,
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incomplete: self.incomplete,
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peers: peers
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})
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})
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} else {
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cb(new Error('invalid event'))
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}
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}
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Swarm.prototype._onAnnounce_started = function (params, peer, cb) {
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if (peer) {
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debug('unexpected `started` event from peer that is already in swarm')
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return this._onAnnounce_update() // treat as an update
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}
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if (params.left === 0) this.complete += 1
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else this.incomplete += 1
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peer = this.peers[params.addr] = {
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ip: params.ip,
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port: params.port,
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peerId: params.peer_id
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}
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this.emit('start', params.addr)
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cb()
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}
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Swarm.prototype._onAnnounce_stopped = function (params, peer, cb) {
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if (!peer) {
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debug('unexpected `stopped` event from peer that is not in swarm')
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return // do nothing
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}
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if (peer.complete) this.complete -= 1
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else this.incomplete -= 1
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this.peers[params.addr] = null
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this.emit('stop', params.addr)
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cb()
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}
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Swarm.prototype._onAnnounce_completed = function (params, peer, cb) {
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if (!peer) {
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debug('unexpected `completed` event from peer that is not in swarm')
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return start() // treat as a start
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}
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if (peer.complete) {
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debug('unexpected `completed` event from peer that is already marked as completed')
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return // do nothing
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}
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this.complete += 1
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this.incomplete -= 1
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peer.complete = true
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this.emit('complete', params.addr)
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cb()
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}
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Swarm.prototype._onAnnounce_update = function (params, peer, cb) {
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if (!peer) {
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debug('unexpected `update` event from peer that is not in swarm')
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return start() // treat as a start
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}
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this.emit('update', params.addr)
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cb()
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}
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Swarm.prototype._getPeers = function (numwant) {
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var peers = []
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for (var peerId in this.peers) {
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if (peers.length >= numwant) break
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var peer = this.peers[peerId]
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if (!peer) continue // ignore null values
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peers.push({
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'peer id': peer.peerId,
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ip: peer.ip,
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port: peer.port
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})
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}
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return peers
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}
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Swarm.prototype.scrape = function (infoHash, params, cb) {
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cb(null, {
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complete: this.complete,
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incomplete: this.incomplete
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})
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}

‎package.json‎

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"ip": "^0.3.0",
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"once": "^1.3.0",
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"portfinder": "^0.2.1",
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"run-series": "^1.0.2",
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"string2compact": "^1.1.1"
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},
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"devDependencies": {

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