modernize index.js

index.js

@@ -1,19 +1,17 @@
-var bencode = require('bencode')
-var BitField = require('bitfield')
-var debug = require('debug')('ut_metadata')
-var EventEmitter = require('events').EventEmitter
-var inherits = require('inherits')
-var sha1 = require('simple-sha1')
+const { EventEmitter } = require('events')
+const bencode = require('bencode')
+const BitField = require('bitfield')
+const debug = require('debug')('ut_metadata')
+const sha1 = require('simple-sha1')
 
-var MAX_METADATA_SIZE = 10000000 // 10MB
-var BITFIELD_GROW = 1000
-var PIECE_LENGTH = 16 * 1024
+const MAX_METADATA_SIZE = 10000000 // 10MB
+const BITFIELD_GROW = 1000
+const PIECE_LENGTH = 16 * 1024
 
-module.exports = function (metadata) {
-  inherits(utMetadata, EventEmitter)
-
-  function utMetadata (wire) {
-    EventEmitter.call(this)
+module.exports = metadata => {
+  class utMetadata extends EventEmitter {
+    constructor (wire) {
+      super()
 
       this._wire = wire
 
@@ -32,14 +30,11 @@ module.exports = function (metadata) {
       }
     }
 
-  // Name of the bittorrent-protocol extension
-  utMetadata.prototype.name = 'ut_metadata'
-
-  utMetadata.prototype.onHandshake = function (infoHash, peerId, extensions) {
+    onHandshake (infoHash, peerId, extensions) {
       this._infoHash = infoHash
     }
 
-  utMetadata.prototype.onExtendedHandshake = function (handshake) {
+    onExtendedHandshake (handshake) {
       if (!handshake.m || !handshake.m.ut_metadata) {
         return this.emit('warning', new Error('Peer does not support ut_metadata'))
       }
@@ -61,11 +56,12 @@ module.exports = function (metadata) {
       }
     }
 
-  utMetadata.prototype.onMessage = function (buf) {
-    var dict, trailer
+    onMessage (buf) {
+      let dict
+      let trailer
       try {
-      var str = buf.toString()
-      var trailerIndex = str.indexOf('ee') + 2
+        const str = buf.toString()
+        const trailerIndex = str.indexOf('ee') + 2
         dict = bencode.decode(str.substring(0, trailerIndex))
         trailer = buf.slice(trailerIndex)
       } catch (err) {
@@ -96,7 +92,7 @@ module.exports = function (metadata) {
      * Ask the peer to send metadata.
      * @public
      */
-  utMetadata.prototype.fetch = function () {
+    fetch () {
       if (this._metadataComplete) {
         return
       }
@@ -110,17 +106,17 @@ module.exports = function (metadata) {
      * Stop asking the peer to send metadata.
      * @public
      */
-  utMetadata.prototype.cancel = function () {
+    cancel () {
       this._fetching = false
     }
 
-  utMetadata.prototype.setMetadata = function (metadata) {
+    setMetadata (metadata) {
       if (this._metadataComplete) return true
       debug('set metadata')
 
       // if full torrent dictionary was passed in, pull out just `info` key
       try {
-      var info = bencode.decode(metadata).info
+        const info = bencode.decode(metadata).info
         if (info) {
           metadata = bencode.encode(info)
         }
@@ -143,45 +139,45 @@ module.exports = function (metadata) {
       return true
     }
 
-  utMetadata.prototype._send = function (dict, trailer) {
-    var buf = bencode.encode(dict)
+    _send (dict, trailer) {
+      let buf = bencode.encode(dict)
       if (Buffer.isBuffer(trailer)) {
         buf = Buffer.concat([buf, trailer])
       }
       this._wire.extended('ut_metadata', buf)
     }
 
-  utMetadata.prototype._request = function (piece) {
-    this._send({ msg_type: 0, piece: piece })
+    _request (piece) {
+      this._send({ msg_type: 0, piece })
     }
 
-  utMetadata.prototype._data = function (piece, buf, totalSize) {
-    var msg = { msg_type: 1, piece: piece }
+    _data (piece, buf, totalSize) {
+      const msg = { msg_type: 1, piece }
       if (typeof totalSize === 'number') {
         msg.total_size = totalSize
       }
       this._send(msg, buf)
     }
 
-  utMetadata.prototype._reject = function (piece) {
-    this._send({ msg_type: 2, piece: piece })
+    _reject (piece) {
+      this._send({ msg_type: 2, piece })
     }
 
-  utMetadata.prototype._onRequest = function (piece) {
+    _onRequest (piece) {
       if (!this._metadataComplete) {
         this._reject(piece)
         return
       }
-    var start = piece * PIECE_LENGTH
-    var end = start + PIECE_LENGTH
+      const start = piece * PIECE_LENGTH
+      let end = start + PIECE_LENGTH
       if (end > this._metadataSize) {
         end = this._metadataSize
       }
-    var buf = this.metadata.slice(start, end)
+      const buf = this.metadata.slice(start, end)
       this._data(piece, buf, this._metadataSize)
     }
 
-  utMetadata.prototype._onData = function (piece, buf, totalSize) {
+    _onData (piece, buf, totalSize) {
       if (buf.length > PIECE_LENGTH) {
         return
       }
@@ -190,7 +186,7 @@ module.exports = function (metadata) {
       this._checkDone()
     }
 
-  utMetadata.prototype._onReject = function (piece) {
+    _onReject (piece) {
       if (this._remainingRejects > 0 && this._fetching) {
         // If we haven't been rejected too much, then try to request the piece again
         this._request(piece)
@@ -200,16 +196,16 @@ module.exports = function (metadata) {
       }
     }
 
-  utMetadata.prototype._requestPieces = function () {
+    _requestPieces () {
       this.metadata = Buffer.alloc(this._metadataSize)
-    for (var piece = 0; piece < this._numPieces; piece++) {
+      for (let piece = 0; piece < this._numPieces; piece++) {
         this._request(piece)
       }
     }
 
-  utMetadata.prototype._checkDone = function () {
-    var done = true
-    for (var piece = 0; piece < this._numPieces; piece++) {
+    _checkDone () {
+      let done = true
+      for (let piece = 0; piece < this._numPieces; piece++) {
         if (!this._bitfield.get(piece)) {
           done = false
           break
@@ -218,14 +214,14 @@ module.exports = function (metadata) {
       if (!done) return
 
       // attempt to set metadata -- may fail sha1 check
-    var success = this.setMetadata(this.metadata)
+      const success = this.setMetadata(this.metadata)
 
       if (!success) {
         this._failedMetadata()
       }
     }
 
-  utMetadata.prototype._failedMetadata = function () {
+    _failedMetadata () {
       // reset bitfield & try again
       this._bitfield = new BitField(0, { grow: BITFIELD_GROW })
       this._remainingRejects -= this._numPieces
@@ -235,6 +231,10 @@ module.exports = function (metadata) {
         this.emit('warning', new Error('Peer sent invalid metadata'))
       }
     }
+  }
+
+  // Name of the bittorrent-protocol extension
+  utMetadata.prototype.name = 'ut_metadata'
 
   return utMetadata
 }