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https://github.com/Ylianst/MeshCentral.git
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353 lines
10 KiB
JavaScript
353 lines
10 KiB
JavaScript
/*
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* Websock: high-performance buffering wrapper
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* Copyright (C) 2019 The noVNC Authors
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* Licensed under MPL 2.0 (see LICENSE.txt)
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*
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* Websock is similar to the standard WebSocket / RTCDataChannel object
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* but with extra buffer handling.
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*
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* Websock has built-in receive queue buffering; the message event
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* does not contain actual data but is simply a notification that
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* there is new data available. Several rQ* methods are available to
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* read binary data off of the receive queue.
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*/
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import * as Log from './util/logging.js';
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// this has performance issues in some versions Chromium, and
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// doesn't gain a tremendous amount of performance increase in Firefox
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// at the moment. It may be valuable to turn it on in the future.
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const MAX_RQ_GROW_SIZE = 40 * 1024 * 1024; // 40 MiB
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// Constants pulled from RTCDataChannelState enum
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// https://developer.mozilla.org/en-US/docs/Web/API/RTCDataChannel/readyState#RTCDataChannelState_enum
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const DataChannel = {
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CONNECTING: "connecting",
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OPEN: "open",
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CLOSING: "closing",
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CLOSED: "closed"
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};
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const ReadyStates = {
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CONNECTING: [WebSocket.CONNECTING, DataChannel.CONNECTING],
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OPEN: [WebSocket.OPEN, DataChannel.OPEN],
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CLOSING: [WebSocket.CLOSING, DataChannel.CLOSING],
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CLOSED: [WebSocket.CLOSED, DataChannel.CLOSED],
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};
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// Properties a raw channel must have, WebSocket and RTCDataChannel are two examples
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const rawChannelProps = [
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"send",
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"close",
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"binaryType",
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"onerror",
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"onmessage",
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"onopen",
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"protocol",
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"readyState",
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];
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export default class Websock {
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constructor() {
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this._websocket = null; // WebSocket or RTCDataChannel object
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this._rQi = 0; // Receive queue index
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this._rQlen = 0; // Next write position in the receive queue
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this._rQbufferSize = 1024 * 1024 * 4; // Receive queue buffer size (4 MiB)
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// called in init: this._rQ = new Uint8Array(this._rQbufferSize);
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this._rQ = null; // Receive queue
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this._sQbufferSize = 1024 * 10; // 10 KiB
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// called in init: this._sQ = new Uint8Array(this._sQbufferSize);
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this._sQlen = 0;
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this._sQ = null; // Send queue
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this._eventHandlers = {
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message: () => {},
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open: () => {},
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close: () => {},
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error: () => {}
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};
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}
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// Getters and Setters
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get readyState() {
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let subState;
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if (this._websocket === null) {
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return "unused";
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}
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subState = this._websocket.readyState;
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if (ReadyStates.CONNECTING.includes(subState)) {
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return "connecting";
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} else if (ReadyStates.OPEN.includes(subState)) {
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return "open";
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} else if (ReadyStates.CLOSING.includes(subState)) {
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return "closing";
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} else if (ReadyStates.CLOSED.includes(subState)) {
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return "closed";
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}
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return "unknown";
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}
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get sQ() {
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return this._sQ;
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}
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get rQ() {
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return this._rQ;
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}
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get rQi() {
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return this._rQi;
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}
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set rQi(val) {
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this._rQi = val;
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}
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// Receive Queue
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get rQlen() {
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return this._rQlen - this._rQi;
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}
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rQpeek8() {
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return this._rQ[this._rQi];
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}
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rQskipBytes(bytes) {
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this._rQi += bytes;
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}
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rQshift8() {
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return this._rQshift(1);
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}
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rQshift16() {
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return this._rQshift(2);
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}
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rQshift32() {
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return this._rQshift(4);
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}
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// TODO(directxman12): test performance with these vs a DataView
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_rQshift(bytes) {
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let res = 0;
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for (let byte = bytes - 1; byte >= 0; byte--) {
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res += this._rQ[this._rQi++] << (byte * 8);
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}
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return res;
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}
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rQshiftStr(len) {
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if (typeof(len) === 'undefined') { len = this.rQlen; }
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let str = "";
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// Handle large arrays in steps to avoid long strings on the stack
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for (let i = 0; i < len; i += 4096) {
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let part = this.rQshiftBytes(Math.min(4096, len - i));
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str += String.fromCharCode.apply(null, part);
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}
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return str;
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}
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rQshiftBytes(len) {
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if (typeof(len) === 'undefined') { len = this.rQlen; }
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this._rQi += len;
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return new Uint8Array(this._rQ.buffer, this._rQi - len, len);
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}
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rQshiftTo(target, len) {
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if (len === undefined) { len = this.rQlen; }
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// TODO: make this just use set with views when using a ArrayBuffer to store the rQ
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target.set(new Uint8Array(this._rQ.buffer, this._rQi, len));
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this._rQi += len;
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}
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rQslice(start, end = this.rQlen) {
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return new Uint8Array(this._rQ.buffer, this._rQi + start, end - start);
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}
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// Check to see if we must wait for 'num' bytes (default to FBU.bytes)
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// to be available in the receive queue. Return true if we need to
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// wait (and possibly print a debug message), otherwise false.
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rQwait(msg, num, goback) {
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if (this.rQlen < num) {
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if (goback) {
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if (this._rQi < goback) {
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throw new Error("rQwait cannot backup " + goback + " bytes");
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}
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this._rQi -= goback;
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}
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return true; // true means need more data
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}
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return false;
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}
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// Send Queue
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flush() {
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if (this._sQlen > 0 && this.readyState === 'open') {
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this._websocket.send(this._encodeMessage());
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this._sQlen = 0;
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}
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}
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send(arr) {
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this._sQ.set(arr, this._sQlen);
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this._sQlen += arr.length;
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this.flush();
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}
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sendString(str) {
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this.send(str.split('').map(chr => chr.charCodeAt(0)));
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}
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// Event Handlers
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off(evt) {
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this._eventHandlers[evt] = () => {};
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}
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on(evt, handler) {
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this._eventHandlers[evt] = handler;
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}
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_allocateBuffers() {
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this._rQ = new Uint8Array(this._rQbufferSize);
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this._sQ = new Uint8Array(this._sQbufferSize);
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}
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init() {
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this._allocateBuffers();
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this._rQi = 0;
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this._websocket = null;
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}
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open(uri, protocols) {
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this.attach(new WebSocket(uri, protocols));
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}
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attach(rawChannel) {
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this.init();
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// Must get object and class methods to be compatible with the tests.
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const channelProps = [...Object.keys(rawChannel), ...Object.getOwnPropertyNames(Object.getPrototypeOf(rawChannel))];
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for (let i = 0; i < rawChannelProps.length; i++) {
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const prop = rawChannelProps[i];
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if (channelProps.indexOf(prop) < 0) {
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throw new Error('Raw channel missing property: ' + prop);
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}
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}
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this._websocket = rawChannel;
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this._websocket.binaryType = "arraybuffer";
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this._websocket.onmessage = this._recvMessage.bind(this);
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this._websocket.onopen = () => {
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Log.Debug('>> WebSock.onopen');
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if (this._websocket.protocol) {
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Log.Info("Server choose sub-protocol: " + this._websocket.protocol);
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}
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this._eventHandlers.open();
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Log.Debug("<< WebSock.onopen");
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};
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this._websocket.onclose = (e) => {
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Log.Debug(">> WebSock.onclose");
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this._eventHandlers.close(e);
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Log.Debug("<< WebSock.onclose");
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};
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this._websocket.onerror = (e) => {
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Log.Debug(">> WebSock.onerror: " + e);
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this._eventHandlers.error(e);
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Log.Debug("<< WebSock.onerror: " + e);
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};
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}
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close() {
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if (this._websocket) {
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if (this.readyState === 'connecting' ||
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this.readyState === 'open') {
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Log.Info("Closing WebSocket connection");
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this._websocket.close();
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}
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this._websocket.onmessage = () => {};
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}
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}
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// private methods
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_encodeMessage() {
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// Put in a binary arraybuffer
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// according to the spec, you can send ArrayBufferViews with the send method
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return new Uint8Array(this._sQ.buffer, 0, this._sQlen);
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}
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// We want to move all the unread data to the start of the queue,
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// e.g. compacting.
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// The function also expands the receive que if needed, and for
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// performance reasons we combine these two actions to avoid
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// unneccessary copying.
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_expandCompactRQ(minFit) {
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// if we're using less than 1/8th of the buffer even with the incoming bytes, compact in place
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// instead of resizing
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const requiredBufferSize = (this._rQlen - this._rQi + minFit) * 8;
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const resizeNeeded = this._rQbufferSize < requiredBufferSize;
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if (resizeNeeded) {
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// Make sure we always *at least* double the buffer size, and have at least space for 8x
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// the current amount of data
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this._rQbufferSize = Math.max(this._rQbufferSize * 2, requiredBufferSize);
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}
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// we don't want to grow unboundedly
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if (this._rQbufferSize > MAX_RQ_GROW_SIZE) {
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this._rQbufferSize = MAX_RQ_GROW_SIZE;
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if (this._rQbufferSize - this.rQlen < minFit) {
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throw new Error("Receive Queue buffer exceeded " + MAX_RQ_GROW_SIZE + " bytes, and the new message could not fit");
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}
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}
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if (resizeNeeded) {
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const oldRQbuffer = this._rQ.buffer;
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this._rQ = new Uint8Array(this._rQbufferSize);
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this._rQ.set(new Uint8Array(oldRQbuffer, this._rQi, this._rQlen - this._rQi));
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} else {
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this._rQ.copyWithin(0, this._rQi, this._rQlen);
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}
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this._rQlen = this._rQlen - this._rQi;
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this._rQi = 0;
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}
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// push arraybuffer values onto the end of the receive que
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_DecodeMessage(data) {
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const u8 = new Uint8Array(data);
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if (u8.length > this._rQbufferSize - this._rQlen) {
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this._expandCompactRQ(u8.length);
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}
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this._rQ.set(u8, this._rQlen);
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this._rQlen += u8.length;
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}
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_recvMessage(e) {
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this._DecodeMessage(e.data);
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if (this.rQlen > 0) {
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this._eventHandlers.message();
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if (this._rQlen == this._rQi) {
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// All data has now been processed, this means we
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// can reset the receive queue.
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this._rQlen = 0;
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this._rQi = 0;
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}
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} else {
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Log.Debug("Ignoring empty message");
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}
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}
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}
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