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590 lines
13 KiB
JavaScript
590 lines
13 KiB
JavaScript
'use strict';
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const safeBuffer = require('safe-buffer');
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const PerMessageDeflate = require('./permessage-deflate');
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const bufferUtil = require('./buffer-util');
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const validation = require('./validation');
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const constants = require('./constants');
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const Buffer = safeBuffer.Buffer;
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const GET_INFO = 0;
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const GET_PAYLOAD_LENGTH_16 = 1;
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const GET_PAYLOAD_LENGTH_64 = 2;
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const GET_MASK = 3;
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const GET_DATA = 4;
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const INFLATING = 5;
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/**
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* HyBi Receiver implementation.
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*/
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class Receiver {
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/**
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* Creates a Receiver instance.
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*
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* @param {Object} extensions An object containing the negotiated extensions
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* @param {Number} maxPayload The maximum allowed message length
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* @param {String} binaryType The type for binary data
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*/
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constructor (extensions, maxPayload, binaryType) {
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this._binaryType = binaryType || constants.BINARY_TYPES[0];
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this._extensions = extensions || {};
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this._maxPayload = maxPayload | 0;
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this._bufferedBytes = 0;
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this._buffers = [];
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this._compressed = false;
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this._payloadLength = 0;
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this._fragmented = 0;
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this._masked = false;
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this._fin = false;
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this._mask = null;
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this._opcode = 0;
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this._totalPayloadLength = 0;
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this._messageLength = 0;
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this._fragments = [];
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this._cleanupCallback = null;
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this._isCleaningUp = false;
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this._hadError = false;
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this._loop = false;
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this.add = this.add.bind(this);
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this.onmessage = null;
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this.onclose = null;
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this.onerror = null;
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this.onping = null;
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this.onpong = null;
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this._state = GET_INFO;
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}
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/**
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* Consumes `n` bytes from the buffered data, calls `cleanup` if necessary.
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*
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* @param {Number} n The number of bytes to consume
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* @return {(Buffer|null)} The consumed bytes or `null` if `n` bytes are not
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* available
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* @private
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*/
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consume (n) {
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if (this._bufferedBytes < n) {
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this._loop = false;
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if (this._isCleaningUp) this.cleanup(this._cleanupCallback);
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return null;
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}
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this._bufferedBytes -= n;
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if (n === this._buffers[0].length) return this._buffers.shift();
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if (n < this._buffers[0].length) {
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const buf = this._buffers[0];
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this._buffers[0] = buf.slice(n);
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return buf.slice(0, n);
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}
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const dst = Buffer.allocUnsafe(n);
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do {
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const buf = this._buffers[0];
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if (n >= buf.length) {
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this._buffers.shift().copy(dst, dst.length - n);
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} else {
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buf.copy(dst, dst.length - n, 0, n);
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this._buffers[0] = buf.slice(n);
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}
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n -= buf.length;
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} while (n > 0);
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return dst;
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}
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/**
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* Adds new data to the parser.
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*
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* @param {Buffer} chunk A chunk of data
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* @public
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*/
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add (chunk) {
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this._bufferedBytes += chunk.length;
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this._buffers.push(chunk);
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this.startLoop();
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}
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/**
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* Starts the parsing loop.
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*
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* @private
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*/
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startLoop () {
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this._loop = true;
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do {
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switch (this._state) {
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case GET_INFO:
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this.getInfo();
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break;
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case GET_PAYLOAD_LENGTH_16:
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this.getPayloadLength16();
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break;
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case GET_PAYLOAD_LENGTH_64:
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this.getPayloadLength64();
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break;
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case GET_MASK:
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this.getMask();
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break;
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case GET_DATA:
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this.getData();
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break;
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default: // `INFLATING`
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this._loop = false;
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}
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} while (this._loop);
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}
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/**
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* Reads the first two bytes of a frame.
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*
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* @private
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*/
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getInfo () {
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const buf = this.consume(2);
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if (buf === null) return;
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if ((buf[0] & 0x30) !== 0x00) {
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this.error(
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new RangeError('Invalid WebSocket frame: RSV2 and RSV3 must be clear'),
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1002
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);
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return;
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}
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const compressed = (buf[0] & 0x40) === 0x40;
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if (compressed && !this._extensions[PerMessageDeflate.extensionName]) {
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this.error(
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new RangeError('Invalid WebSocket frame: RSV1 must be clear'),
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1002
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);
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return;
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}
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this._fin = (buf[0] & 0x80) === 0x80;
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this._opcode = buf[0] & 0x0f;
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this._payloadLength = buf[1] & 0x7f;
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if (this._opcode === 0x00) {
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if (compressed) {
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this.error(
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new RangeError('Invalid WebSocket frame: RSV1 must be clear'),
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1002
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);
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return;
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}
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if (!this._fragmented) {
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this.error(
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new RangeError('Invalid WebSocket frame: invalid opcode 0'),
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1002
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);
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return;
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} else {
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this._opcode = this._fragmented;
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}
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} else if (this._opcode === 0x01 || this._opcode === 0x02) {
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if (this._fragmented) {
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this.error(
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new RangeError(
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`Invalid WebSocket frame: invalid opcode ${this._opcode}`
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),
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1002
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);
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return;
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}
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this._compressed = compressed;
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} else if (this._opcode > 0x07 && this._opcode < 0x0b) {
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if (!this._fin) {
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this.error(
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new RangeError('Invalid WebSocket frame: FIN must be set'),
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1002
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);
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return;
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}
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if (compressed) {
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this.error(
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new RangeError('Invalid WebSocket frame: RSV1 must be clear'),
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1002
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);
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return;
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}
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if (this._payloadLength > 0x7d) {
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this.error(
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new RangeError(
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`Invalid WebSocket frame: invalid payload length ` +
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`${this._payloadLength}`
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),
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1002
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);
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return;
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}
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} else {
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this.error(
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new RangeError(
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`Invalid WebSocket frame: invalid opcode ${this._opcode}`
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),
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1002
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);
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return;
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}
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if (!this._fin && !this._fragmented) this._fragmented = this._opcode;
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this._masked = (buf[1] & 0x80) === 0x80;
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if (this._payloadLength === 126) this._state = GET_PAYLOAD_LENGTH_16;
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else if (this._payloadLength === 127) this._state = GET_PAYLOAD_LENGTH_64;
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else this.haveLength();
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}
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/**
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* Gets extended payload length (7+16).
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*
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* @private
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*/
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getPayloadLength16 () {
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const buf = this.consume(2);
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if (buf === null) return;
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this._payloadLength = buf.readUInt16BE(0, true);
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this.haveLength();
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}
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/**
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* Gets extended payload length (7+64).
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*
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* @private
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*/
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getPayloadLength64 () {
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const buf = this.consume(8);
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if (buf === null) return;
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const num = buf.readUInt32BE(0, true);
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//
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// The maximum safe integer in JavaScript is 2^53 - 1. An error is returned
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// if payload length is greater than this number.
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//
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if (num > Math.pow(2, 53 - 32) - 1) {
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this.error(
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new RangeError(
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'Unsupported WebSocket frame: payload length > 2^53 - 1'
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),
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1009
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);
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return;
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}
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this._payloadLength = num * Math.pow(2, 32) + buf.readUInt32BE(4, true);
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this.haveLength();
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}
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/**
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* Payload length has been read.
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*
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* @private
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*/
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haveLength () {
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if (this._opcode < 0x08 && this.maxPayloadExceeded(this._payloadLength)) {
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return;
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}
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if (this._masked) this._state = GET_MASK;
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else this._state = GET_DATA;
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}
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/**
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* Reads mask bytes.
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*
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* @private
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*/
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getMask () {
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this._mask = this.consume(4);
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if (this._mask === null) return;
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this._state = GET_DATA;
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}
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/**
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* Reads data bytes.
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*
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* @private
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*/
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getData () {
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var data = constants.EMPTY_BUFFER;
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if (this._payloadLength) {
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data = this.consume(this._payloadLength);
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if (data === null) return;
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if (this._masked) bufferUtil.unmask(data, this._mask);
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}
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if (this._opcode > 0x07) {
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this.controlMessage(data);
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} else if (this._compressed) {
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this._state = INFLATING;
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this.decompress(data);
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} else if (this.pushFragment(data)) {
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this.dataMessage();
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}
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}
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/**
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* Decompresses data.
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*
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* @param {Buffer} data Compressed data
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* @private
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*/
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decompress (data) {
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const perMessageDeflate = this._extensions[PerMessageDeflate.extensionName];
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perMessageDeflate.decompress(data, this._fin, (err, buf) => {
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if (err) {
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this.error(err, err.closeCode === 1009 ? 1009 : 1007);
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return;
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}
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if (this.pushFragment(buf)) this.dataMessage();
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this.startLoop();
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});
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}
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/**
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* Handles a data message.
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*
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* @private
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*/
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dataMessage () {
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if (this._fin) {
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const messageLength = this._messageLength;
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const fragments = this._fragments;
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this._totalPayloadLength = 0;
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this._messageLength = 0;
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this._fragmented = 0;
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this._fragments = [];
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if (this._opcode === 2) {
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var data;
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if (this._binaryType === 'nodebuffer') {
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data = toBuffer(fragments, messageLength);
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} else if (this._binaryType === 'arraybuffer') {
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data = toArrayBuffer(toBuffer(fragments, messageLength));
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} else {
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data = fragments;
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}
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this.onmessage(data);
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} else {
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const buf = toBuffer(fragments, messageLength);
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if (!validation.isValidUTF8(buf)) {
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this.error(
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new Error('Invalid WebSocket frame: invalid UTF-8 sequence'),
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1007
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);
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return;
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}
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this.onmessage(buf.toString());
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}
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}
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this._state = GET_INFO;
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}
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/**
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* Handles a control message.
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*
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* @param {Buffer} data Data to handle
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* @private
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*/
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controlMessage (data) {
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if (this._opcode === 0x08) {
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if (data.length === 0) {
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this._loop = false;
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this.onclose(1005, '');
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this.cleanup(this._cleanupCallback);
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} else if (data.length === 1) {
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this.error(
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new RangeError('Invalid WebSocket frame: invalid payload length 1'),
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1002
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);
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} else {
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const code = data.readUInt16BE(0, true);
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if (!validation.isValidStatusCode(code)) {
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this.error(
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new RangeError(
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`Invalid WebSocket frame: invalid status code ${code}`
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),
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1002
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);
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return;
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}
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const buf = data.slice(2);
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if (!validation.isValidUTF8(buf)) {
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this.error(
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new Error('Invalid WebSocket frame: invalid UTF-8 sequence'),
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1007
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);
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return;
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}
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this._loop = false;
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this.onclose(code, buf.toString());
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this.cleanup(this._cleanupCallback);
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}
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return;
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}
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if (this._opcode === 0x09) this.onping(data);
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else this.onpong(data);
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this._state = GET_INFO;
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}
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/**
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* Handles an error.
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*
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* @param {Error} err The error
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* @param {Number} code Close code
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* @private
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*/
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error (err, code) {
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this._hadError = true;
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this._loop = false;
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this.onerror(err, code);
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this.cleanup(this._cleanupCallback);
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}
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/**
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* Checks payload size, disconnects socket when it exceeds `maxPayload`.
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*
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* @param {Number} length Payload length
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* @private
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*/
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maxPayloadExceeded (length) {
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if (length === 0 || this._maxPayload < 1) return false;
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const fullLength = this._totalPayloadLength + length;
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if (fullLength <= this._maxPayload) {
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this._totalPayloadLength = fullLength;
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return false;
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}
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this.error(new RangeError('Max payload size exceeded'), 1009);
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return true;
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}
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/**
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* Appends a fragment in the fragments array after checking that the sum of
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* fragment lengths does not exceed `maxPayload`.
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*
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* @param {Buffer} fragment The fragment to add
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* @return {Boolean} `true` if `maxPayload` is not exceeded, else `false`
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* @private
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*/
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pushFragment (fragment) {
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if (fragment.length === 0) return true;
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const totalLength = this._messageLength + fragment.length;
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if (this._maxPayload < 1 || totalLength <= this._maxPayload) {
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this._messageLength = totalLength;
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this._fragments.push(fragment);
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return true;
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}
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this.error(new RangeError('Max payload size exceeded'), 1009);
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return false;
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}
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/**
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* Releases resources used by the receiver.
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*
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* @param {Function} cb Callback
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* @public
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*/
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cleanup (cb) {
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if (this._extensions === null) {
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if (cb) cb();
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return;
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}
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if (!this._hadError && (this._loop || this._state === INFLATING)) {
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this._cleanupCallback = cb;
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this._isCleaningUp = true;
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return;
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}
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this._extensions = null;
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this._fragments = null;
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this._buffers = null;
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this._mask = null;
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this._cleanupCallback = null;
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this.onmessage = null;
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this.onclose = null;
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this.onerror = null;
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this.onping = null;
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this.onpong = null;
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if (cb) cb();
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}
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}
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module.exports = Receiver;
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/**
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* Makes a buffer from a list of fragments.
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*
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* @param {Buffer[]} fragments The list of fragments composing the message
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* @param {Number} messageLength The length of the message
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* @return {Buffer}
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* @private
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*/
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function toBuffer (fragments, messageLength) {
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if (fragments.length === 1) return fragments[0];
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if (fragments.length > 1) return bufferUtil.concat(fragments, messageLength);
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return constants.EMPTY_BUFFER;
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}
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/**
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* Converts a buffer to an `ArrayBuffer`.
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*
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* @param {Buffer} The buffer to convert
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* @return {ArrayBuffer} Converted buffer
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*/
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function toArrayBuffer (buf) {
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if (buf.byteOffset === 0 && buf.byteLength === buf.buffer.byteLength) {
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return buf.buffer;
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}
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return buf.buffer.slice(buf.byteOffset, buf.byteOffset + buf.byteLength);
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}
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