345 lines
10 KiB
JavaScript
345 lines
10 KiB
JavaScript
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"use strict";
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Object.defineProperty(exports, "__esModule", { value: true });
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exports.Polling = void 0;
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const transport_1 = require("../transport");
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const zlib_1 = require("zlib");
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const accepts = require("accepts");
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const debug_1 = require("debug");
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const debug = (0, debug_1.default)("engine:polling");
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const compressionMethods = {
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gzip: zlib_1.createGzip,
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deflate: zlib_1.createDeflate,
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};
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class Polling extends transport_1.Transport {
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/**
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* HTTP polling constructor.
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*
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* @api public.
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*/
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constructor(req) {
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super(req);
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this.closeTimeout = 30 * 1000;
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}
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/**
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* Transport name
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*
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* @api public
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*/
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get name() {
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return "polling";
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}
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get supportsFraming() {
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return false;
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}
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/**
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* Overrides onRequest.
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*
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* @param {http.IncomingMessage}
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* @api private
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*/
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onRequest(req) {
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const res = req.res;
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if ("GET" === req.method) {
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this.onPollRequest(req, res);
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}
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else if ("POST" === req.method) {
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this.onDataRequest(req, res);
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}
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else {
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res.writeHead(500);
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res.end();
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}
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}
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/**
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* The client sends a request awaiting for us to send data.
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*
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* @api private
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*/
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onPollRequest(req, res) {
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if (this.req) {
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debug("request overlap");
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// assert: this.res, '.req and .res should be (un)set together'
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this.onError("overlap from client");
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// TODO for the next major release: use an HTTP 400 status code (https://github.com/socketio/engine.io/issues/650)
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res.writeHead(500);
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res.end();
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return;
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}
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debug("setting request");
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this.req = req;
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this.res = res;
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const onClose = () => {
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this.onError("poll connection closed prematurely");
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};
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const cleanup = () => {
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req.removeListener("close", onClose);
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this.req = this.res = null;
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};
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req.cleanup = cleanup;
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req.on("close", onClose);
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this.writable = true;
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this.emit("drain");
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// if we're still writable but had a pending close, trigger an empty send
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if (this.writable && this.shouldClose) {
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debug("triggering empty send to append close packet");
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this.send([{ type: "noop" }]);
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}
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}
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/**
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* The client sends a request with data.
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*
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* @api private
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*/
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onDataRequest(req, res) {
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if (this.dataReq) {
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// assert: this.dataRes, '.dataReq and .dataRes should be (un)set together'
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this.onError("data request overlap from client");
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// TODO for the next major release: use an HTTP 400 status code (https://github.com/socketio/engine.io/issues/650)
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res.writeHead(500);
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res.end();
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return;
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}
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const isBinary = "application/octet-stream" === req.headers["content-type"];
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if (isBinary && this.protocol === 4) {
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return this.onError("invalid content");
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}
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this.dataReq = req;
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this.dataRes = res;
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let chunks = isBinary ? Buffer.concat([]) : "";
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const cleanup = () => {
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req.removeListener("data", onData);
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req.removeListener("end", onEnd);
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req.removeListener("close", onClose);
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this.dataReq = this.dataRes = chunks = null;
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};
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const onClose = () => {
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cleanup();
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this.onError("data request connection closed prematurely");
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};
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const onData = (data) => {
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let contentLength;
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if (isBinary) {
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chunks = Buffer.concat([chunks, data]);
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contentLength = chunks.length;
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}
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else {
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chunks += data;
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contentLength = Buffer.byteLength(chunks);
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}
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if (contentLength > this.maxHttpBufferSize) {
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res.writeHead(413).end();
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cleanup();
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}
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};
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const onEnd = () => {
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this.onData(chunks);
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const headers = {
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// text/html is required instead of text/plain to avoid an
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// unwanted download dialog on certain user-agents (GH-43)
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"Content-Type": "text/html",
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"Content-Length": 2,
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};
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res.writeHead(200, this.headers(req, headers));
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res.end("ok");
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cleanup();
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};
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req.on("close", onClose);
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if (!isBinary)
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req.setEncoding("utf8");
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req.on("data", onData);
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req.on("end", onEnd);
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}
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/**
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* Processes the incoming data payload.
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*
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* @param {String} encoded payload
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* @api private
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*/
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onData(data) {
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debug('received "%s"', data);
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const callback = (packet) => {
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if ("close" === packet.type) {
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debug("got xhr close packet");
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this.onClose();
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return false;
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}
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this.onPacket(packet);
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};
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if (this.protocol === 3) {
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this.parser.decodePayload(data, callback);
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}
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else {
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this.parser.decodePayload(data).forEach(callback);
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}
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}
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/**
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* Overrides onClose.
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*
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* @api private
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*/
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onClose() {
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if (this.writable) {
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// close pending poll request
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this.send([{ type: "noop" }]);
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}
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super.onClose();
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}
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/**
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* Writes a packet payload.
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*
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* @param {Object} packet
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* @api private
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*/
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send(packets) {
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this.writable = false;
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if (this.shouldClose) {
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debug("appending close packet to payload");
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packets.push({ type: "close" });
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this.shouldClose();
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this.shouldClose = null;
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}
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const doWrite = (data) => {
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const compress = packets.some((packet) => {
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return packet.options && packet.options.compress;
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});
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this.write(data, { compress });
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};
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if (this.protocol === 3) {
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this.parser.encodePayload(packets, this.supportsBinary, doWrite);
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}
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else {
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this.parser.encodePayload(packets, doWrite);
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}
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}
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/**
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* Writes data as response to poll request.
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*
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* @param {String} data
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* @param {Object} options
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* @api private
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*/
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write(data, options) {
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debug('writing "%s"', data);
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this.doWrite(data, options, () => {
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this.req.cleanup();
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});
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}
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/**
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* Performs the write.
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*
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* @api private
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*/
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doWrite(data, options, callback) {
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// explicit UTF-8 is required for pages not served under utf
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const isString = typeof data === "string";
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const contentType = isString
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? "text/plain; charset=UTF-8"
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: "application/octet-stream";
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const headers = {
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"Content-Type": contentType,
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};
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const respond = (data) => {
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headers["Content-Length"] =
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"string" === typeof data ? Buffer.byteLength(data) : data.length;
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this.res.writeHead(200, this.headers(this.req, headers));
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this.res.end(data);
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callback();
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};
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if (!this.httpCompression || !options.compress) {
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respond(data);
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return;
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}
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const len = isString ? Buffer.byteLength(data) : data.length;
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if (len < this.httpCompression.threshold) {
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respond(data);
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return;
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}
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const encoding = accepts(this.req).encodings(["gzip", "deflate"]);
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if (!encoding) {
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respond(data);
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return;
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}
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this.compress(data, encoding, (err, data) => {
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if (err) {
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this.res.writeHead(500);
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this.res.end();
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callback(err);
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return;
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}
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headers["Content-Encoding"] = encoding;
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respond(data);
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});
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}
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/**
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* Compresses data.
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*
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* @api private
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*/
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compress(data, encoding, callback) {
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debug("compressing");
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const buffers = [];
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let nread = 0;
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compressionMethods[encoding](this.httpCompression)
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.on("error", callback)
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.on("data", function (chunk) {
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buffers.push(chunk);
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nread += chunk.length;
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})
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.on("end", function () {
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callback(null, Buffer.concat(buffers, nread));
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})
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.end(data);
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}
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/**
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* Closes the transport.
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*
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* @api private
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*/
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doClose(fn) {
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debug("closing");
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let closeTimeoutTimer;
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if (this.dataReq) {
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debug("aborting ongoing data request");
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this.dataReq.destroy();
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}
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const onClose = () => {
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clearTimeout(closeTimeoutTimer);
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fn();
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this.onClose();
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};
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if (this.writable) {
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debug("transport writable - closing right away");
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this.send([{ type: "close" }]);
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onClose();
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}
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else if (this.discarded) {
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debug("transport discarded - closing right away");
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onClose();
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}
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else {
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debug("transport not writable - buffering orderly close");
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this.shouldClose = onClose;
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closeTimeoutTimer = setTimeout(onClose, this.closeTimeout);
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}
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}
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/**
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* Returns headers for a response.
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*
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* @param {http.IncomingMessage} request
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* @param {Object} extra headers
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* @api private
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*/
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headers(req, headers) {
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headers = headers || {};
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// prevent XSS warnings on IE
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// https://github.com/LearnBoost/socket.io/pull/1333
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const ua = req.headers["user-agent"];
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if (ua && (~ua.indexOf(";MSIE") || ~ua.indexOf("Trident/"))) {
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headers["X-XSS-Protection"] = "0";
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}
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this.emit("headers", headers, req);
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return headers;
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}
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}
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exports.Polling = Polling;
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