twitst4tz

index.js (10823B)

---

 /**
  * Module dependencies.
  */
 
 var utf8 = require('./utf8');
 var hasBinary = require('has-binary2');
 var after = require('after');
 var keys = require('./keys');
 
 /**
  * Current protocol version.
  */
 exports.protocol = 3;
 
 /**
  * Packet types.
  */
 
 var packets = exports.packets = {
     open:     0    // non-ws
   , close:    1    // non-ws
   , ping:     2
   , pong:     3
   , message:  4
   , upgrade:  5
   , noop:     6
 };
 
 var packetslist = keys(packets);
 
 /**
  * Premade error packet.
  */
 
 var err = { type: 'error', data: 'parser error' };
 
 const EMPTY_BUFFER = Buffer.concat([]);
 
 /**
  * Encodes a packet.
  *
  *     <packet type id> [ <data> ]
  *
  * Example:
  *
  *     5hello world
  *     3
  *     4
  *
  * Binary is encoded in an identical principle
  *
  * @api private
  */
 
 exports.encodePacket = function (packet, supportsBinary, utf8encode, callback) {
   if (typeof supportsBinary === 'function') {
     callback = supportsBinary;
     supportsBinary = null;
   }
 
   if (typeof utf8encode === 'function') {
     callback = utf8encode;
     utf8encode = null;
   }
 
   if (Buffer.isBuffer(packet.data)) {
     return encodeBuffer(packet, supportsBinary, callback);
   } else if (packet.data && (packet.data.buffer || packet.data) instanceof ArrayBuffer) {
     return encodeBuffer({ type: packet.type, data: arrayBufferToBuffer(packet.data) }, supportsBinary, callback);
   }
 
   // Sending data as a utf-8 string
   var encoded = packets[packet.type];
 
   // data fragment is optional
   if (undefined !== packet.data) {
     encoded += utf8encode ? utf8.encode(String(packet.data), { strict: false }) : String(packet.data);
   }
 
   return callback('' + encoded);
 };
 
 /**
  * Encode Buffer data
  */
 
 function encodeBuffer(packet, supportsBinary, callback) {
   if (!supportsBinary) {
     return exports.encodeBase64Packet(packet, callback);
   }
 
   var data = packet.data;
   var typeBuffer = Buffer.allocUnsafe(1);
   typeBuffer[0] = packets[packet.type];
   return callback(Buffer.concat([typeBuffer, data]));
 }
 
 /**
  * Encodes a packet with binary data in a base64 string
  *
  * @param {Object} packet, has `type` and `data`
  * @return {String} base64 encoded message
  */
 
 exports.encodeBase64Packet = function(packet, callback){
   var data = Buffer.isBuffer(packet.data) ? packet.data : arrayBufferToBuffer(packet.data);
   var message = 'b' + packets[packet.type];
   message += data.toString('base64');
   return callback(message);
 };
 
 /**
  * Decodes a packet. Data also available as an ArrayBuffer if requested.
  *
  * @return {Object} with `type` and `data` (if any)
  * @api private
  */
 
 exports.decodePacket = function (data, binaryType, utf8decode) {
   if (data === undefined) {
     return err;
   }
 
   var type;
 
   // String data
   if (typeof data === 'string') {
 
     type = data.charAt(0);
 
     if (type === 'b') {
       return exports.decodeBase64Packet(data.substr(1), binaryType);
     }
 
     if (utf8decode) {
       data = tryDecode(data);
       if (data === false) {
         return err;
       }
     }
 
     if (Number(type) != type || !packetslist[type]) {
       return err;
     }
 
     if (data.length > 1) {
       return { type: packetslist[type], data: data.substring(1) };
     } else {
       return { type: packetslist[type] };
     }
   }
 
   // Binary data
   if (binaryType === 'arraybuffer') {
     // wrap Buffer/ArrayBuffer data into an Uint8Array
     var intArray = new Uint8Array(data);
     type = intArray[0];
     return { type: packetslist[type], data: intArray.buffer.slice(1) };
   }
 
   if (data instanceof ArrayBuffer) {
     data = arrayBufferToBuffer(data);
   }
   type = data[0];
   return { type: packetslist[type], data: data.slice(1) };
 };
 
 function tryDecode(data) {
   try {
     data = utf8.decode(data, { strict: false });
   } catch (e) {
     return false;
   }
   return data;
 }
 
 /**
  * Decodes a packet encoded in a base64 string.
  *
  * @param {String} base64 encoded message
  * @return {Object} with `type` and `data` (if any)
  */
 
 exports.decodeBase64Packet = function(msg, binaryType) {
   var type = packetslist[msg.charAt(0)];
   var data = Buffer.from(msg.substr(1), 'base64');
   if (binaryType === 'arraybuffer') {
     var abv = new Uint8Array(data.length);
     for (var i = 0; i < abv.length; i++){
       abv[i] = data[i];
     }
     data = abv.buffer;
   }
   return { type: type, data: data };
 };
 
 /**
  * Encodes multiple messages (payload).
  *
  *     <length>:data
  *
  * Example:
  *
  *     11:hello world2:hi
  *
  * If any contents are binary, they will be encoded as base64 strings. Base64
  * encoded strings are marked with a b before the length specifier
  *
  * @param {Array} packets
  * @api private
  */
 
 exports.encodePayload = function (packets, supportsBinary, callback) {
   if (typeof supportsBinary === 'function') {
     callback = supportsBinary;
     supportsBinary = null;
   }
 
   if (supportsBinary && hasBinary(packets)) {
     return exports.encodePayloadAsBinary(packets, callback);
   }
 
   if (!packets.length) {
     return callback('0:');
   }
 
   function encodeOne(packet, doneCallback) {
     exports.encodePacket(packet, supportsBinary, false, function(message) {
       doneCallback(null, setLengthHeader(message));
     });
   }
 
   map(packets, encodeOne, function(err, results) {
     return callback(results.join(''));
   });
 };
 
 function setLengthHeader(message) {
   return message.length + ':' + message;
 }
 
 /**
  * Async array map using after
  */
 
 function map(ary, each, done) {
   var result = new Array(ary.length);
   var next = after(ary.length, done);
 
   for (var i = 0; i < ary.length; i++) {
     each(ary[i], function(error, msg) {
       result[i] = msg;
       next(error, result);
     });
   }
 }
 
 /*
  * Decodes data when a payload is maybe expected. Possible binary contents are
  * decoded from their base64 representation
  *
  * @param {String} data, callback method
  * @api public
  */
 
 exports.decodePayload = function (data, binaryType, callback) {
   if (typeof data !== 'string') {
     return exports.decodePayloadAsBinary(data, binaryType, callback);
   }
 
   if (typeof binaryType === 'function') {
     callback = binaryType;
     binaryType = null;
   }
 
   if (data === '') {
     // parser error - ignoring payload
     return callback(err, 0, 1);
   }
 
   var length = '', n, msg, packet;
 
   for (var i = 0, l = data.length; i < l; i++) {
     var chr = data.charAt(i);
 
     if (chr !== ':') {
       length += chr;
       continue;
     }
 
     if (length === '' || (length != (n = Number(length)))) {
       // parser error - ignoring payload
       return callback(err, 0, 1);
     }
 
     msg = data.substr(i + 1, n);
 
     if (length != msg.length) {
       // parser error - ignoring payload
       return callback(err, 0, 1);
     }
 
     if (msg.length) {
       packet = exports.decodePacket(msg, binaryType, false);
 
       if (err.type === packet.type && err.data === packet.data) {
         // parser error in individual packet - ignoring payload
         return callback(err, 0, 1);
       }
 
       var more = callback(packet, i + n, l);
       if (false === more) return;
     }
 
     // advance cursor
     i += n;
     length = '';
   }
 
   if (length !== '') {
     // parser error - ignoring payload
     return callback(err, 0, 1);
   }
 
 };
 
 /**
  *
  * Converts a buffer to a utf8.js encoded string
  *
  * @api private
  */
 
 function bufferToString(buffer) {
   var str = '';
   for (var i = 0, l = buffer.length; i < l; i++) {
     str += String.fromCharCode(buffer[i]);
   }
   return str;
 }
 
 /**
  *
  * Converts a utf8.js encoded string to a buffer
  *
  * @api private
  */
 
 function stringToBuffer(string) {
   var buf = Buffer.allocUnsafe(string.length);
   for (var i = 0, l = string.length; i < l; i++) {
     buf.writeUInt8(string.charCodeAt(i), i);
   }
   return buf;
 }
 
 /**
  *
  * Converts an ArrayBuffer to a Buffer
  *
  * @api private
  */
 
 function arrayBufferToBuffer(data) {
   // data is either an ArrayBuffer or ArrayBufferView.
   var length = data.byteLength || data.length;
   var offset = data.byteOffset || 0;
 
   return Buffer.from(data.buffer || data, offset, length);
 }
 
 /**
  * Encodes multiple messages (payload) as binary.
  *
  * <1 = binary, 0 = string><number from 0-9><number from 0-9>[...]<number
  * 255><data>
  *
  * Example:
  * 1 3 255 1 2 3, if the binary contents are interpreted as 8 bit integers
  *
  * @param {Array} packets
  * @return {Buffer} encoded payload
  * @api private
  */
 
 exports.encodePayloadAsBinary = function (packets, callback) {
   if (!packets.length) {
     return callback(EMPTY_BUFFER);
   }
 
   map(packets, encodeOneBinaryPacket, function(err, results) {
     return callback(Buffer.concat(results));
   });
 };
 
 function encodeOneBinaryPacket(p, doneCallback) {
 
   function onBinaryPacketEncode(packet) {
 
     var encodingLength = '' + packet.length;
     var sizeBuffer;
 
     if (typeof packet === 'string') {
       sizeBuffer = Buffer.allocUnsafe(encodingLength.length + 2);
       sizeBuffer[0] = 0; // is a string (not true binary = 0)
       for (var i = 0; i < encodingLength.length; i++) {
         sizeBuffer[i + 1] = parseInt(encodingLength[i], 10);
       }
       sizeBuffer[sizeBuffer.length - 1] = 255;
       return doneCallback(null, Buffer.concat([sizeBuffer, stringToBuffer(packet)]));
     }
 
     sizeBuffer = Buffer.allocUnsafe(encodingLength.length + 2);
     sizeBuffer[0] = 1; // is binary (true binary = 1)
     for (var i = 0; i < encodingLength.length; i++) {
       sizeBuffer[i + 1] = parseInt(encodingLength[i], 10);
     }
     sizeBuffer[sizeBuffer.length - 1] = 255;
 
     doneCallback(null, Buffer.concat([sizeBuffer, packet]));
   }
 
   exports.encodePacket(p, true, true, onBinaryPacketEncode);
 
 }
 
 
 /*
  * Decodes data when a payload is maybe expected. Strings are decoded by
  * interpreting each byte as a key code for entries marked to start with 0. See
  * description of encodePayloadAsBinary
 
  * @param {Buffer} data, callback method
  * @api public
  */
 
 exports.decodePayloadAsBinary = function (data, binaryType, callback) {
   if (typeof binaryType === 'function') {
     callback = binaryType;
     binaryType = null;
   }
 
   var bufferTail = data;
   var buffers = [];
   var i;
 
   while (bufferTail.length > 0) {
     var strLen = '';
     var isString = bufferTail[0] === 0;
     for (i = 1; ; i++) {
       if (bufferTail[i] === 255)  break;
       // 310 = char length of Number.MAX_VALUE
       if (strLen.length > 310) {
         return callback(err, 0, 1);
       }
       strLen += '' + bufferTail[i];
     }
     bufferTail = bufferTail.slice(strLen.length + 1);
 
     var msgLength = parseInt(strLen, 10);
 
     var msg = bufferTail.slice(1, msgLength + 1);
     if (isString) msg = bufferToString(msg);
     buffers.push(msg);
     bufferTail = bufferTail.slice(msgLength + 1);
   }
 
   var total = buffers.length;
   for (i = 0; i < total; i++) {
     var buffer = buffers[i];
     callback(exports.decodePacket(buffer, binaryType, true), i, total);
   }
 };