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"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Polling = void 0;
const transport_1 = require("../transport");
const zlib_1 = require("zlib");
const accepts = require("accepts");
const debug_1 = require("debug");
const debug = (0, debug_1.default)("engine:polling");
const compressionMethods = {
gzip: zlib_1.createGzip,
deflate: zlib_1.createDeflate,
};
class Polling extends transport_1.Transport {
/**
* HTTP polling constructor.
*
* @api public.
*/
constructor(req) {
super(req);
this.closeTimeout = 30 * 1000;
}
/**
* Transport name
*
* @api public
*/
get name() {
return "polling";
}
get supportsFraming() {
return false;
}
/**
* Overrides onRequest.
*
* @param req
*
* @api private
*/
onRequest(req) {
const res = req.res;
// remove the reference to the ServerResponse object (as the first request of the session is kept in memory by default)
req.res = null;
if (req.getMethod() === "get") {
this.onPollRequest(req, res);
}
else if (req.getMethod() === "post") {
this.onDataRequest(req, res);
}
else {
res.writeStatus("500 Internal Server Error");
res.end();
}
}
/**
* The client sends a request awaiting for us to send data.
*
* @api private
*/
onPollRequest(req, res) {
if (this.req) {
debug("request overlap");
// assert: this.res, '.req and .res should be (un)set together'
this.onError("overlap from client");
res.writeStatus("500 Internal Server Error");
res.end();
return;
}
debug("setting request");
this.req = req;
this.res = res;
const onClose = () => {
this.writable = false;
this.onError("poll connection closed prematurely");
};
const cleanup = () => {
this.req = this.res = null;
};
req.cleanup = cleanup;
res.onAborted(onClose);
this.writable = true;
this.emit("drain");
// if we're still writable but had a pending close, trigger an empty send
if (this.writable && this.shouldClose) {
debug("triggering empty send to append close packet");
this.send([{ type: "noop" }]);
}
}
/**
* The client sends a request with data.
*
* @api private
*/
onDataRequest(req, res) {
if (this.dataReq) {
// assert: this.dataRes, '.dataReq and .dataRes should be (un)set together'
this.onError("data request overlap from client");
res.writeStatus("500 Internal Server Error");
res.end();
return;
}
const expectedContentLength = Number(req.headers["content-length"]);
if (!expectedContentLength) {
this.onError("content-length header required");
res.writeStatus("411 Length Required").end();
return;
}
if (expectedContentLength > this.maxHttpBufferSize) {
this.onError("payload too large");
res.writeStatus("413 Payload Too Large").end();
return;
}
const isBinary = "application/octet-stream" === req.headers["content-type"];
if (isBinary && this.protocol === 4) {
return this.onError("invalid content");
}
this.dataReq = req;
this.dataRes = res;
let buffer;
let offset = 0;
const headers = {
// text/html is required instead of text/plain to avoid an
// unwanted download dialog on certain user-agents (GH-43)
"Content-Type": "text/html",
};
this.headers(req, headers);
for (let key in headers) {
res.writeHeader(key, String(headers[key]));
}
const onEnd = (buffer) => {
this.onData(buffer.toString());
this.onDataRequestCleanup();
res.cork(() => {
res.end("ok");
});
};
res.onAborted(() => {
this.onDataRequestCleanup();
this.onError("data request connection closed prematurely");
});
res.onData((arrayBuffer, isLast) => {
const totalLength = offset + arrayBuffer.byteLength;
if (totalLength > expectedContentLength) {
this.onError("content-length mismatch");
res.close(); // calls onAborted
return;
}
if (!buffer) {
if (isLast) {
onEnd(Buffer.from(arrayBuffer));
return;
}
buffer = Buffer.allocUnsafe(expectedContentLength);
}
Buffer.from(arrayBuffer).copy(buffer, offset);
if (isLast) {
if (totalLength != expectedContentLength) {
this.onError("content-length mismatch");
res.writeStatus("400 Content-Length Mismatch").end();
this.onDataRequestCleanup();
return;
}
onEnd(buffer);
return;
}
offset = totalLength;
});
}
/**
* Cleanup request.
*
* @api private
*/
onDataRequestCleanup() {
this.dataReq = this.dataRes = null;
}
/**
* Processes the incoming data payload.
*
* @param {String} encoded payload
* @api private
*/
onData(data) {
debug('received "%s"', data);
const callback = (packet) => {
if ("close" === packet.type) {
debug("got xhr close packet");
this.onClose();
return false;
}
this.onPacket(packet);
};
if (this.protocol === 3) {
this.parser.decodePayload(data, callback);
}
else {
this.parser.decodePayload(data).forEach(callback);
}
}
/**
* Overrides onClose.
*
* @api private
*/
onClose() {
if (this.writable) {
// close pending poll request
this.send([{ type: "noop" }]);
}
super.onClose();
}
/**
* Writes a packet payload.
*
* @param {Object} packet
* @api private
*/
send(packets) {
this.writable = false;
if (this.shouldClose) {
debug("appending close packet to payload");
packets.push({ type: "close" });
this.shouldClose();
this.shouldClose = null;
}
const doWrite = (data) => {
const compress = packets.some((packet) => {
return packet.options && packet.options.compress;
});
this.write(data, { compress });
};
if (this.protocol === 3) {
this.parser.encodePayload(packets, this.supportsBinary, doWrite);
}
else {
this.parser.encodePayload(packets, doWrite);
}
}
/**
* Writes data as response to poll request.
*
* @param {String} data
* @param {Object} options
* @api private
*/
write(data, options) {
debug('writing "%s"', data);
this.doWrite(data, options, () => {
this.req.cleanup();
});
}
/**
* Performs the write.
*
* @api private
*/
doWrite(data, options, callback) {
// explicit UTF-8 is required for pages not served under utf
const isString = typeof data === "string";
const contentType = isString
? "text/plain; charset=UTF-8"
: "application/octet-stream";
const headers = {
"Content-Type": contentType,
};
const respond = (data) => {
this.headers(this.req, headers);
this.res.cork(() => {
Object.keys(headers).forEach((key) => {
this.res.writeHeader(key, String(headers[key]));
});
this.res.end(data);
});
callback();
};
if (!this.httpCompression || !options.compress) {
respond(data);
return;
}
const len = isString ? Buffer.byteLength(data) : data.length;
if (len < this.httpCompression.threshold) {
respond(data);
return;
}
const encoding = accepts(this.req).encodings(["gzip", "deflate"]);
if (!encoding) {
respond(data);
return;
}
this.compress(data, encoding, (err, data) => {
if (err) {
this.res.writeStatus("500 Internal Server Error");
this.res.end();
callback(err);
return;
}
headers["Content-Encoding"] = encoding;
respond(data);
});
}
/**
* Compresses data.
*
* @api private
*/
compress(data, encoding, callback) {
debug("compressing");
const buffers = [];
let nread = 0;
compressionMethods[encoding](this.httpCompression)
.on("error", callback)
.on("data", function (chunk) {
buffers.push(chunk);
nread += chunk.length;
})
.on("end", function () {
callback(null, Buffer.concat(buffers, nread));
})
.end(data);
}
/**
* Closes the transport.
*
* @api private
*/
doClose(fn) {
debug("closing");
let closeTimeoutTimer;
const onClose = () => {
clearTimeout(closeTimeoutTimer);
fn();
this.onClose();
};
if (this.writable) {
debug("transport writable - closing right away");
this.send([{ type: "close" }]);
onClose();
}
else if (this.discarded) {
debug("transport discarded - closing right away");
onClose();
}
else {
debug("transport not writable - buffering orderly close");
this.shouldClose = onClose;
closeTimeoutTimer = setTimeout(onClose, this.closeTimeout);
}
}
/**
* Returns headers for a response.
*
* @param req - request
* @param {Object} extra headers
* @api private
*/
headers(req, headers) {
headers = headers || {};
// prevent XSS warnings on IE
// https://github.com/LearnBoost/socket.io/pull/1333
const ua = req.headers["user-agent"];
if (ua && (~ua.indexOf(";MSIE") || ~ua.indexOf("Trident/"))) {
headers["X-XSS-Protection"] = "0";
}
headers["cache-control"] = "no-store";
this.emit("headers", headers, req);
return headers;
}
}
exports.Polling = Polling;
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