dynatrace-cordova-outsystems-plugin/node_modules/ws/lib/receiver.js

This plugin gives you the ability to use the Dynatrace instrumentation in your hybrid application (Cordova, Ionic, ..). It uses the Mobile Agent, the JavaScript Agent and the Javascript Bridge. The Mobile Agent will give you all device specific values con

'use strict';

const { Writable } = require('stream');

const PerMessageDeflate = require('./permessage-deflate');
const {
  BINARY_TYPES,
  EMPTY_BUFFER,
  kStatusCode,
  kWebSocket
} = require('./constants');
const { concat, toArrayBuffer, unmask } = require('./buffer-util');
const { isValidStatusCode, isValidUTF8 } = require('./validation');

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 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 || BINARY_TYPES[0];
    this[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 && this._state == GET_INFO) 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 = EMPTY_BUFFER;

    if (this._payloadLength) {
      if (this._bufferedBytes < this._payloadLength) {
        this._loop = false;
        return;
      }

      data = this.consume(this._payloadLength);
      if (this._masked) 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 = concat(fragments, messageLength);
        } else if (this._binaryType === 'arraybuffer') {
          data = toArrayBuffer(concat(fragments, messageLength));
        } else {
          data = fragments;
        }

        this.emit('message', data);
      } else {
        const buf = concat(fragments, messageLength);

        if (!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 (!isValidStatusCode(code)) {
          return error(RangeError, `invalid status code ${code}`, true, 1002);
        }

        const buf = data.slice(2);

        if (!isValidUTF8(buf)) {
          return error(Error, 'invalid UTF-8 sequence', true, 1007);
        }

        this.emit('conclude', code, buf.toString());
        this.end();
      }
    } else 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[kStatusCode] = statusCode;
  return err;
}