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node_modules/ws/lib/receiver.js

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+'use strict';
+
+const stream = require('stream');
+
+const PerMessageDeflate = require('./permessage-deflate');
+const bufferUtil = require('./buffer-util');
+const validation = require('./validation');
+const constants = require('./constants');
+
+const GET_INFO = 0;
+const GET_PAYLOAD_LENGTH_16 = 1;
+const GET_PAYLOAD_LENGTH_64 = 2;
+const GET_MASK = 3;
+const GET_DATA = 4;
+const INFLATING = 5;
+
+/**
+ * HyBi Receiver implementation.
+ *
+ * @extends stream.Writable
+ */
+class Receiver extends stream.Writable {
+  /**
+   * Creates a Receiver instance.
+   *
+   * @param {String} binaryType The type for binary data
+   * @param {Object} extensions An object containing the negotiated extensions
+   * @param {Number} maxPayload The maximum allowed message length
+   */
+  constructor (binaryType, extensions, maxPayload) {
+    super();
+
+    this._binaryType = binaryType || constants.BINARY_TYPES[0];
+    this[constants.kWebSocket] = undefined;
+    this._extensions = extensions || {};
+    this._maxPayload = maxPayload | 0;
+
+    this._bufferedBytes = 0;
+    this._buffers = [];
+
+    this._compressed = false;
+    this._payloadLength = 0;
+    this._mask = undefined;
+    this._fragmented = 0;
+    this._masked = false;
+    this._fin = false;
+    this._opcode = 0;
+
+    this._totalPayloadLength = 0;
+    this._messageLength = 0;
+    this._fragments = [];
+
+    this._state = GET_INFO;
+    this._loop = false;
+  }
+
+  /**
+   * Implements `Writable.prototype._write()`.
+   *
+   * @param {Buffer} chunk The chunk of data to write
+   * @param {String} encoding The character encoding of `chunk`
+   * @param {Function} cb Callback
+   */
+  _write (chunk, encoding, cb) {
+    if (this._opcode === 0x08) return cb();
+
+    this._bufferedBytes += chunk.length;
+    this._buffers.push(chunk);
+    this.startLoop(cb);
+  }
+
+  /**
+   * Consumes `n` bytes from the buffered data.
+   *
+   * @param {Number} n The number of bytes to consume
+   * @return {Buffer} The consumed bytes
+   * @private
+   */
+  consume (n) {
+    this._bufferedBytes -= n;
+
+    if (n === this._buffers[0].length) return this._buffers.shift();
+
+    if (n < this._buffers[0].length) {
+      const buf = this._buffers[0];
+      this._buffers[0] = buf.slice(n);
+      return buf.slice(0, n);
+    }
+
+    const dst = Buffer.allocUnsafe(n);
+
+    do {
+      const buf = this._buffers[0];
+
+      if (n >= buf.length) {
+        this._buffers.shift().copy(dst, dst.length - n);
+      } else {
+        buf.copy(dst, dst.length - n, 0, n);
+        this._buffers[0] = buf.slice(n);
+      }
+
+      n -= buf.length;
+    } while (n > 0);
+
+    return dst;
+  }
+
+  /**
+   * Starts the parsing loop.
+   *
+   * @param {Function} cb Callback
+   * @private
+   */
+  startLoop (cb) {
+    var err;
+    this._loop = true;
+
+    do {
+      switch (this._state) {
+        case GET_INFO:
+          err = this.getInfo();
+          break;
+        case GET_PAYLOAD_LENGTH_16:
+          err = this.getPayloadLength16();
+          break;
+        case GET_PAYLOAD_LENGTH_64:
+          err = this.getPayloadLength64();
+          break;
+        case GET_MASK:
+          this.getMask();
+          break;
+        case GET_DATA:
+          err = this.getData(cb);
+          break;
+        default: // `INFLATING`
+          this._loop = false;
+          return;
+      }
+    } while (this._loop);
+
+    cb(err);
+  }
+
+  /**
+   * Reads the first two bytes of a frame.
+   *
+   * @return {(RangeError|undefined)} A possible error
+   * @private
+   */
+  getInfo () {
+    if (this._bufferedBytes < 2) {
+      this._loop = false;
+      return;
+    }
+
+    const buf = this.consume(2);
+
+    if ((buf[0] & 0x30) !== 0x00) {
+      this._loop = false;
+      return error(RangeError, 'RSV2 and RSV3 must be clear', true, 1002);
+    }
+
+    const compressed = (buf[0] & 0x40) === 0x40;
+
+    if (compressed && !this._extensions[PerMessageDeflate.extensionName]) {
+      this._loop = false;
+      return error(RangeError, 'RSV1 must be clear', true, 1002);
+    }
+
+    this._fin = (buf[0] & 0x80) === 0x80;
+    this._opcode = buf[0] & 0x0f;
+    this._payloadLength = buf[1] & 0x7f;
+
+    if (this._opcode === 0x00) {
+      if (compressed) {
+        this._loop = false;
+        return error(RangeError, 'RSV1 must be clear', true, 1002);
+      }
+
+      if (!this._fragmented) {
+        this._loop = false;
+        return error(RangeError, 'invalid opcode 0', true, 1002);
+      }
+
+      this._opcode = this._fragmented;
+    } else if (this._opcode === 0x01 || this._opcode === 0x02) {
+      if (this._fragmented) {
+        this._loop = false;
+        return error(RangeError, `invalid opcode ${this._opcode}`, true, 1002);
+      }
+
+      this._compressed = compressed;
+    } else if (this._opcode > 0x07 && this._opcode < 0x0b) {
+      if (!this._fin) {
+        this._loop = false;
+        return error(RangeError, 'FIN must be set', true, 1002);
+      }
+
+      if (compressed) {
+        this._loop = false;
+        return error(RangeError, 'RSV1 must be clear', true, 1002);
+      }
+
+      if (this._payloadLength > 0x7d) {
+        this._loop = false;
+        return error(
+          RangeError,
+          `invalid payload length ${this._payloadLength}`,
+          true,
+          1002
+        );
+      }
+    } else {
+      this._loop = false;
+      return error(RangeError, `invalid opcode ${this._opcode}`, true, 1002);
+    }
+
+    if (!this._fin && !this._fragmented) this._fragmented = this._opcode;
+    this._masked = (buf[1] & 0x80) === 0x80;
+
+    if (this._payloadLength === 126) this._state = GET_PAYLOAD_LENGTH_16;
+    else if (this._payloadLength === 127) this._state = GET_PAYLOAD_LENGTH_64;
+    else return this.haveLength();
+  }
+
+  /**
+   * Gets extended payload length (7+16).
+   *
+   * @return {(RangeError|undefined)} A possible error
+   * @private
+   */
+  getPayloadLength16 () {
+    if (this._bufferedBytes < 2) {
+      this._loop = false;
+      return;
+    }
+
+    this._payloadLength = this.consume(2).readUInt16BE(0);
+    return this.haveLength();
+  }
+
+  /**
+   * Gets extended payload length (7+64).
+   *
+   * @return {(RangeError|undefined)} A possible error
+   * @private
+   */
+  getPayloadLength64 () {
+    if (this._bufferedBytes < 8) {
+      this._loop = false;
+      return;
+    }
+
+    const buf = this.consume(8);
+    const num = buf.readUInt32BE(0);
+
+    //
+    // The maximum safe integer in JavaScript is 2^53 - 1. An error is returned
+    // if payload length is greater than this number.
+    //
+    if (num > Math.pow(2, 53 - 32) - 1) {
+      this._loop = false;
+      return error(
+        RangeError,
+        'Unsupported WebSocket frame: payload length > 2^53 - 1',
+        false,
+        1009
+      );
+    }
+
+    this._payloadLength = num * Math.pow(2, 32) + buf.readUInt32BE(4);
+    return this.haveLength();
+  }
+
+  /**
+   * Payload length has been read.
+   *
+   * @return {(RangeError|undefined)} A possible error
+   * @private
+   */
+  haveLength () {
+    if (this._payloadLength && this._opcode < 0x08) {
+      this._totalPayloadLength += this._payloadLength;
+      if (this._totalPayloadLength > this._maxPayload && this._maxPayload > 0) {
+        this._loop = false;
+        return error(RangeError, 'Max payload size exceeded', false, 1009);
+      }
+    }
+
+    if (this._masked) this._state = GET_MASK;
+    else this._state = GET_DATA;
+  }
+
+  /**
+   * Reads mask bytes.
+   *
+   * @private
+   */
+  getMask () {
+    if (this._bufferedBytes < 4) {
+      this._loop = false;
+      return;
+    }
+
+    this._mask = this.consume(4);
+    this._state = GET_DATA;
+  }
+
+  /**
+   * Reads data bytes.
+   *
+   * @param {Function} cb Callback
+   * @return {(Error|RangeError|undefined)} A possible error
+   * @private
+   */
+  getData (cb) {
+    var data = constants.EMPTY_BUFFER;
+
+    if (this._payloadLength) {
+      if (this._bufferedBytes < this._payloadLength) {
+        this._loop = false;
+        return;
+      }
+
+      data = this.consume(this._payloadLength);
+      if (this._masked) bufferUtil.unmask(data, this._mask);
+    }
+
+    if (this._opcode > 0x07) return this.controlMessage(data);
+
+    if (this._compressed) {
+      this._state = INFLATING;
+      this.decompress(data, cb);
+      return;
+    }
+
+    if (data.length) {
+      //
+      // This message is not compressed so its lenght is the sum of the payload
+      // length of all fragments.
+      //
+      this._messageLength = this._totalPayloadLength;
+      this._fragments.push(data);
+    }
+
+    return this.dataMessage();
+  }
+
+  /**
+   * Decompresses data.
+   *
+   * @param {Buffer} data Compressed data
+   * @param {Function} cb Callback
+   * @private
+   */
+  decompress (data, cb) {
+    const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
+
+    perMessageDeflate.decompress(data, this._fin, (err, buf) => {
+      if (err) return cb(err);
+
+      if (buf.length) {
+        this._messageLength += buf.length;
+        if (this._messageLength > this._maxPayload && this._maxPayload > 0) {
+          return cb(error(RangeError, 'Max payload size exceeded', false, 1009));
+        }
+
+        this._fragments.push(buf);
+      }
+
+      const er = this.dataMessage();
+      if (er) return cb(er);
+
+      this.startLoop(cb);
+    });
+  }
+
+  /**
+   * Handles a data message.
+   *
+   * @return {(Error|undefined)} A possible error
+   * @private
+   */
+  dataMessage () {
+    if (this._fin) {
+      const messageLength = this._messageLength;
+      const fragments = this._fragments;
+
+      this._totalPayloadLength = 0;
+      this._messageLength = 0;
+      this._fragmented = 0;
+      this._fragments = [];
+
+      if (this._opcode === 2) {
+        var data;
+
+        if (this._binaryType === 'nodebuffer') {
+          data = toBuffer(fragments, messageLength);
+        } else if (this._binaryType === 'arraybuffer') {
+          data = toArrayBuffer(toBuffer(fragments, messageLength));
+        } else {
+          data = fragments;
+        }
+
+        this.emit('message', data);
+      } else {
+        const buf = toBuffer(fragments, messageLength);
+
+        if (!validation.isValidUTF8(buf)) {
+          this._loop = false;
+          return error(Error, 'invalid UTF-8 sequence', true, 1007);
+        }
+
+        this.emit('message', buf.toString());
+      }
+    }
+
+    this._state = GET_INFO;
+  }
+
+  /**
+   * Handles a control message.
+   *
+   * @param {Buffer} data Data to handle
+   * @return {(Error|RangeError|undefined)} A possible error
+   * @private
+   */
+  controlMessage (data) {
+    if (this._opcode === 0x08) {
+      this._loop = false;
+
+      if (data.length === 0) {
+        this.emit('conclude', 1005, '');
+        this.end();
+      } else if (data.length === 1) {
+        return error(RangeError, 'invalid payload length 1', true, 1002);
+      } else {
+        const code = data.readUInt16BE(0);
+
+        if (!validation.isValidStatusCode(code)) {
+          return error(RangeError, `invalid status code ${code}`, true, 1002);
+        }
+
+        const buf = data.slice(2);
+
+        if (!validation.isValidUTF8(buf)) {
+          return error(Error, 'invalid UTF-8 sequence', true, 1007);
+        }
+
+        this.emit('conclude', code, buf.toString());
+        this.end();
+      }
+
+      return;
+    }
+
+    if (this._opcode === 0x09) this.emit('ping', data);
+    else this.emit('pong', data);
+
+    this._state = GET_INFO;
+  }
+}
+
+module.exports = Receiver;
+
+/**
+ * Builds an error object.
+ *
+ * @param {(Error|RangeError)} ErrorCtor The error constructor
+ * @param {String} message The error message
+ * @param {Boolean} prefix Specifies whether or not to add a default prefix to
+ *     `message`
+ * @param {Number} statusCode The status code
+ * @return {(Error|RangeError)} The error
+ * @private
+ */
+function error (ErrorCtor, message, prefix, statusCode) {
+  const err = new ErrorCtor(
+    prefix ? `Invalid WebSocket frame: ${message}` : message
+  );
+
+  Error.captureStackTrace(err, error);
+  err[constants.kStatusCode] = statusCode;
+  return err;
+}
+
+/**
+ * Makes a buffer from a list of fragments.
+ *
+ * @param {Buffer[]} fragments The list of fragments composing the message
+ * @param {Number} messageLength The length of the message
+ * @return {Buffer}
+ * @private
+ */
+function toBuffer (fragments, messageLength) {
+  if (fragments.length === 1) return fragments[0];
+  if (fragments.length > 1) return bufferUtil.concat(fragments, messageLength);
+  return constants.EMPTY_BUFFER;
+}
+
+/**
+ * Converts a buffer to an `ArrayBuffer`.
+ *
+ * @param {Buffer} The buffer to convert
+ * @return {ArrayBuffer} Converted buffer
+ */
+function toArrayBuffer (buf) {
+  if (buf.byteOffset === 0 && buf.byteLength === buf.buffer.byteLength) {
+    return buf.buffer;
+  }
+
+  return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
+}