"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Server = exports.BaseServer = void 0;
const qs = require("querystring");
const url_1 = require("url");
const base64id = require("base64id");
const transports_1 = require("./transports");
const events_1 = require("events");
const socket_1 = require("./socket");
const debug_1 = require("debug");
const cookie_1 = require("cookie");
const ws_1 = require("ws");
const webtransport_1 = require("./transports/webtransport");
const engine_io_parser_1 = require("engine.io-parser");
const debug = (0, debug_1.default)("engine");
const kResponseHeaders = Symbol("responseHeaders");
function parseSessionId(data) {
    try {
        const parsed = JSON.parse(data);
        if (typeof parsed.sid === "string") {
            return parsed.sid;
        }
    }
    catch (e) { }
}
class BaseServer extends events_1.EventEmitter {
    /**
     * Server constructor.
     *
     * @param {Object} opts - options
     * @api public
     */
    constructor(opts = {}) {
        super();
        this.middlewares = [];
        this.clients = {};
        this.clientsCount = 0;
        this.opts = Object.assign({
            wsEngine: ws_1.Server,
            pingTimeout: 20000,
            pingInterval: 25000,
            upgradeTimeout: 10000,
            maxHttpBufferSize: 1e6,
            transports: ["polling", "websocket"],
            allowUpgrades: true,
            httpCompression: {
                threshold: 1024,
            },
            cors: false,
            allowEIO3: false,
        }, opts);
        if (opts.cookie) {
            this.opts.cookie = Object.assign({
                name: "io",
                path: "/",
                // @ts-ignore
                httpOnly: opts.cookie.path !== false,
                sameSite: "lax",
            }, opts.cookie);
        }
        if (this.opts.cors) {
            this.use(require("cors")(this.opts.cors));
        }
        if (opts.perMessageDeflate) {
            this.opts.perMessageDeflate = Object.assign({
                threshold: 1024,
            }, opts.perMessageDeflate);
        }
        this.init();
    }
    /**
     * Compute the pathname of the requests that are handled by the server
     * @param options
     * @protected
     */
    _computePath(options) {
        let path = (options.path || "/engine.io").replace(/\/$/, "");
        if (options.addTrailingSlash !== false) {
            // normalize path
            path += "/";
        }
        return path;
    }
    /**
     * Returns a list of available transports for upgrade given a certain transport.
     *
     * @return {Array}
     * @api public
     */
    upgrades(transport) {
        if (!this.opts.allowUpgrades)
            return [];
        return transports_1.default[transport].upgradesTo || [];
    }
    /**
     * Verifies a request.
     *
     * @param {http.IncomingMessage}
     * @return {Boolean} whether the request is valid
     * @api private
     */
    verify(req, upgrade, fn) {
        // transport check
        const transport = req._query.transport;
        // WebTransport does not go through the verify() method, see the onWebTransportSession() method
        if (!~this.opts.transports.indexOf(transport) ||
            transport === "webtransport") {
            debug('unknown transport "%s"', transport);
            return fn(Server.errors.UNKNOWN_TRANSPORT, { transport });
        }
        // 'Origin' header check
        const isOriginInvalid = checkInvalidHeaderChar(req.headers.origin);
        if (isOriginInvalid) {
            const origin = req.headers.origin;
            req.headers.origin = null;
            debug("origin header invalid");
            return fn(Server.errors.BAD_REQUEST, {
                name: "INVALID_ORIGIN",
                origin,
            });
        }
        // sid check
        const sid = req._query.sid;
        if (sid) {
            if (!this.clients.hasOwnProperty(sid)) {
                debug('unknown sid "%s"', sid);
                return fn(Server.errors.UNKNOWN_SID, {
                    sid,
                });
            }
            const previousTransport = this.clients[sid].transport.name;
            if (!upgrade && previousTransport !== transport) {
                debug("bad request: unexpected transport without upgrade");
                return fn(Server.errors.BAD_REQUEST, {
                    name: "TRANSPORT_MISMATCH",
                    transport,
                    previousTransport,
                });
            }
        }
        else {
            // handshake is GET only
            if ("GET" !== req.method) {
                return fn(Server.errors.BAD_HANDSHAKE_METHOD, {
                    method: req.method,
                });
            }
            if (transport === "websocket" && !upgrade) {
                debug("invalid transport upgrade");
                return fn(Server.errors.BAD_REQUEST, {
                    name: "TRANSPORT_HANDSHAKE_ERROR",
                });
            }
            if (!this.opts.allowRequest)
                return fn();
            return this.opts.allowRequest(req, (message, success) => {
                if (!success) {
                    return fn(Server.errors.FORBIDDEN, {
                        message,
                    });
                }
                fn();
            });
        }
        fn();
    }
    /**
     * Adds a new middleware.
     *
     * @example
     * import helmet from "helmet";
     *
     * engine.use(helmet());
     *
     * @param fn
     */
    use(fn) {
        this.middlewares.push(fn);
    }
    /**
     * Apply the middlewares to the request.
     *
     * @param req
     * @param res
     * @param callback
     * @protected
     */
    _applyMiddlewares(req, res, callback) {
        if (this.middlewares.length === 0) {
            debug("no middleware to apply, skipping");
            return callback();
        }
        const apply = (i) => {
            debug("applying middleware n°%d", i + 1);
            this.middlewares[i](req, res, (err) => {
                if (err) {
                    return callback(err);
                }
                if (i + 1 < this.middlewares.length) {
                    apply(i + 1);
                }
                else {
                    callback();
                }
            });
        };
        apply(0);
    }
    /**
     * Closes all clients.
     *
     * @api public
     */
    close() {
        debug("closing all open clients");
        for (let i in this.clients) {
            if (this.clients.hasOwnProperty(i)) {
                this.clients[i].close(true);
            }
        }
        this.cleanup();
        return this;
    }
    /**
     * generate a socket id.
     * Overwrite this method to generate your custom socket id
     *
     * @param {Object} request object
     * @api public
     */
    generateId(req) {
        return base64id.generateId();
    }
    /**
     * Handshakes a new client.
     *
     * @param {String} transport name
     * @param {Object} request object
     * @param {Function} closeConnection
     *
     * @api protected
     */
    async handshake(transportName, req, closeConnection) {
        const protocol = req._query.EIO === "4" ? 4 : 3; // 3rd revision by default
        if (protocol === 3 && !this.opts.allowEIO3) {
            debug("unsupported protocol version");
            this.emit("connection_error", {
                req,
                code: Server.errors.UNSUPPORTED_PROTOCOL_VERSION,
                message: Server.errorMessages[Server.errors.UNSUPPORTED_PROTOCOL_VERSION],
                context: {
                    protocol,
                },
            });
            closeConnection(Server.errors.UNSUPPORTED_PROTOCOL_VERSION);
            return;
        }
        let id;
        try {
            id = await this.generateId(req);
        }
        catch (e) {
            debug("error while generating an id");
            this.emit("connection_error", {
                req,
                code: Server.errors.BAD_REQUEST,
                message: Server.errorMessages[Server.errors.BAD_REQUEST],
                context: {
                    name: "ID_GENERATION_ERROR",
                    error: e,
                },
            });
            closeConnection(Server.errors.BAD_REQUEST);
            return;
        }
        debug('handshaking client "%s"', id);
        try {
            var transport = this.createTransport(transportName, req);
            if ("polling" === transportName) {
                transport.maxHttpBufferSize = this.opts.maxHttpBufferSize;
                transport.httpCompression = this.opts.httpCompression;
            }
            else if ("websocket" === transportName) {
                transport.perMessageDeflate = this.opts.perMessageDeflate;
            }
            if (req._query && req._query.b64) {
                transport.supportsBinary = false;
            }
            else {
                transport.supportsBinary = true;
            }
        }
        catch (e) {
            debug('error handshaking to transport "%s"', transportName);
            this.emit("connection_error", {
                req,
                code: Server.errors.BAD_REQUEST,
                message: Server.errorMessages[Server.errors.BAD_REQUEST],
                context: {
                    name: "TRANSPORT_HANDSHAKE_ERROR",
                    error: e,
                },
            });
            closeConnection(Server.errors.BAD_REQUEST);
            return;
        }
        const socket = new socket_1.Socket(id, this, transport, req, protocol);
        transport.on("headers", (headers, req) => {
            const isInitialRequest = !req._query.sid;
            if (isInitialRequest) {
                if (this.opts.cookie) {
                    headers["Set-Cookie"] = [
                        // @ts-ignore
                        (0, cookie_1.serialize)(this.opts.cookie.name, id, this.opts.cookie),
                    ];
                }
                this.emit("initial_headers", headers, req);
            }
            this.emit("headers", headers, req);
        });
        transport.onRequest(req);
        this.clients[id] = socket;
        this.clientsCount++;
        socket.once("close", () => {
            delete this.clients[id];
            this.clientsCount--;
        });
        this.emit("connection", socket);
        return transport;
    }
    async onWebTransportSession(session) {
        const timeout = setTimeout(() => {
            debug("the client failed to establish a bidirectional stream in the given period");
            session.close();
        }, this.opts.upgradeTimeout);
        const streamReader = session.incomingBidirectionalStreams.getReader();
        const result = await streamReader.read();
        if (result.done) {
            debug("session is closed");
            return;
        }
        const stream = result.value;
        const transformStream = (0, engine_io_parser_1.createPacketDecoderStream)(this.opts.maxHttpBufferSize, "nodebuffer");
        const reader = stream.readable.pipeThrough(transformStream).getReader();
        // reading the first packet of the stream
        const { value, done } = await reader.read();
        if (done) {
            debug("stream is closed");
            return;
        }
        clearTimeout(timeout);
        if (value.type !== "open") {
            debug("invalid WebTransport handshake");
            return session.close();
        }
        if (value.data === undefined) {
            const transport = new webtransport_1.WebTransport(session, stream, reader);
            // note: we cannot use "this.generateId()", because there is no "req" argument
            const id = base64id.generateId();
            debug('handshaking client "%s" (WebTransport)', id);
            const socket = new socket_1.Socket(id, this, transport, null, 4);
            this.clients[id] = socket;
            this.clientsCount++;
            socket.once("close", () => {
                delete this.clients[id];
                this.clientsCount--;
            });
            this.emit("connection", socket);
            return;
        }
        const sid = parseSessionId(value.data);
        if (!sid) {
            debug("invalid WebTransport handshake");
            return session.close();
        }
        const client = this.clients[sid];
        if (!client) {
            debug("upgrade attempt for closed client");
            session.close();
        }
        else if (client.upgrading) {
            debug("transport has already been trying to upgrade");
            session.close();
        }
        else if (client.upgraded) {
            debug("transport had already been upgraded");
            session.close();
        }
        else {
            debug("upgrading existing transport");
            const transport = new webtransport_1.WebTransport(session, stream, reader);
            client.maybeUpgrade(transport);
        }
    }
}
exports.BaseServer = BaseServer;
/**
 * Protocol errors mappings.
 */
BaseServer.errors = {
    UNKNOWN_TRANSPORT: 0,
    UNKNOWN_SID: 1,
    BAD_HANDSHAKE_METHOD: 2,
    BAD_REQUEST: 3,
    FORBIDDEN: 4,
    UNSUPPORTED_PROTOCOL_VERSION: 5,
};
BaseServer.errorMessages = {
    0: "Transport unknown",
    1: "Session ID unknown",
    2: "Bad handshake method",
    3: "Bad request",
    4: "Forbidden",
    5: "Unsupported protocol version",
};
/**
 * Exposes a subset of the http.ServerResponse interface, in order to be able to apply the middlewares to an upgrade
 * request.
 *
 * @see https://nodejs.org/api/http.html#class-httpserverresponse
 */
class WebSocketResponse {
    constructor(req, socket) {
        this.req = req;
        this.socket = socket;
        // temporarily store the response headers on the req object (see the "headers" event)
        req[kResponseHeaders] = {};
    }
    setHeader(name, value) {
        this.req[kResponseHeaders][name] = value;
    }
    getHeader(name) {
        return this.req[kResponseHeaders][name];
    }
    removeHeader(name) {
        delete this.req[kResponseHeaders][name];
    }
    write() { }
    writeHead() { }
    end() {
        // we could return a proper error code, but the WebSocket client will emit an "error" event anyway.
        this.socket.destroy();
    }
}
class Server extends BaseServer {
    /**
     * Initialize websocket server
     *
     * @api protected
     */
    init() {
        if (!~this.opts.transports.indexOf("websocket"))
            return;
        if (this.ws)
            this.ws.close();
        this.ws = new this.opts.wsEngine({
            noServer: true,
            clientTracking: false,
            perMessageDeflate: this.opts.perMessageDeflate,
            maxPayload: this.opts.maxHttpBufferSize,
        });
        if (typeof this.ws.on === "function") {
            this.ws.on("headers", (headersArray, req) => {
                // note: 'ws' uses an array of headers, while Engine.IO uses an object (response.writeHead() accepts both formats)
                // we could also try to parse the array and then sync the values, but that will be error-prone
                const additionalHeaders = req[kResponseHeaders] || {};
                delete req[kResponseHeaders];
                const isInitialRequest = !req._query.sid;
                if (isInitialRequest) {
                    this.emit("initial_headers", additionalHeaders, req);
                }
                this.emit("headers", additionalHeaders, req);
                debug("writing headers: %j", additionalHeaders);
                Object.keys(additionalHeaders).forEach((key) => {
                    headersArray.push(`${key}: ${additionalHeaders[key]}`);
                });
            });
        }
    }
    cleanup() {
        if (this.ws) {
            debug("closing webSocketServer");
            this.ws.close();
            // don't delete this.ws because it can be used again if the http server starts listening again
        }
    }
    /**
     * Prepares a request by processing the query string.
     *
     * @api private
     */
    prepare(req) {
        // try to leverage pre-existing `req._query` (e.g: from connect)
        if (!req._query) {
            req._query = ~req.url.indexOf("?") ? qs.parse((0, url_1.parse)(req.url).query) : {};
        }
    }
    createTransport(transportName, req) {
        return new transports_1.default[transportName](req);
    }
    /**
     * Handles an Engine.IO HTTP request.
     *
     * @param {IncomingMessage} req
     * @param {ServerResponse} res
     * @api public
     */
    handleRequest(req, res) {
        debug('handling "%s" http request "%s"', req.method, req.url);
        this.prepare(req);
        // @ts-ignore
        req.res = res;
        const callback = (errorCode, errorContext) => {
            if (errorCode !== undefined) {
                this.emit("connection_error", {
                    req,
                    code: errorCode,
                    message: Server.errorMessages[errorCode],
                    context: errorContext,
                });
                abortRequest(res, errorCode, errorContext);
                return;
            }
            // @ts-ignore
            if (req._query.sid) {
                debug("setting new request for existing client");
                // @ts-ignore
                this.clients[req._query.sid].transport.onRequest(req);
            }
            else {
                const closeConnection = (errorCode, errorContext) => abortRequest(res, errorCode, errorContext);
                // @ts-ignore
                this.handshake(req._query.transport, req, closeConnection);
            }
        };
        this._applyMiddlewares(req, res, (err) => {
            if (err) {
                callback(Server.errors.BAD_REQUEST, { name: "MIDDLEWARE_FAILURE" });
            }
            else {
                this.verify(req, false, callback);
            }
        });
    }
    /**
     * Handles an Engine.IO HTTP Upgrade.
     *
     * @api public
     */
    handleUpgrade(req, socket, upgradeHead) {
        this.prepare(req);
        const res = new WebSocketResponse(req, socket);
        const callback = (errorCode, errorContext) => {
            if (errorCode !== undefined) {
                this.emit("connection_error", {
                    req,
                    code: errorCode,
                    message: Server.errorMessages[errorCode],
                    context: errorContext,
                });
                abortUpgrade(socket, errorCode, errorContext);
                return;
            }
            const head = Buffer.from(upgradeHead);
            upgradeHead = null;
            // some middlewares (like express-session) wait for the writeHead() call to flush their headers
            // see https://github.com/expressjs/session/blob/1010fadc2f071ddf2add94235d72224cf65159c6/index.js#L220-L244
            res.writeHead();
            // delegate to ws
            this.ws.handleUpgrade(req, socket, head, (websocket) => {
                this.onWebSocket(req, socket, websocket);
            });
        };
        this._applyMiddlewares(req, res, (err) => {
            if (err) {
                callback(Server.errors.BAD_REQUEST, { name: "MIDDLEWARE_FAILURE" });
            }
            else {
                this.verify(req, true, callback);
            }
        });
    }
    /**
     * Called upon a ws.io connection.
     *
     * @param {ws.Socket} websocket
     * @api private
     */
    onWebSocket(req, socket, websocket) {
        websocket.on("error", onUpgradeError);
        if (transports_1.default[req._query.transport] !== undefined &&
            !transports_1.default[req._query.transport].prototype.handlesUpgrades) {
            debug("transport doesnt handle upgraded requests");
            websocket.close();
            return;
        }
        // get client id
        const id = req._query.sid;
        // keep a reference to the ws.Socket
        req.websocket = websocket;
        if (id) {
            const client = this.clients[id];
            if (!client) {
                debug("upgrade attempt for closed client");
                websocket.close();
            }
            else if (client.upgrading) {
                debug("transport has already been trying to upgrade");
                websocket.close();
            }
            else if (client.upgraded) {
                debug("transport had already been upgraded");
                websocket.close();
            }
            else {
                debug("upgrading existing transport");
                // transport error handling takes over
                websocket.removeListener("error", onUpgradeError);
                const transport = this.createTransport(req._query.transport, req);
                if (req._query && req._query.b64) {
                    transport.supportsBinary = false;
                }
                else {
                    transport.supportsBinary = true;
                }
                transport.perMessageDeflate = this.opts.perMessageDeflate;
                client.maybeUpgrade(transport);
            }
        }
        else {
            const closeConnection = (errorCode, errorContext) => abortUpgrade(socket, errorCode, errorContext);
            this.handshake(req._query.transport, req, closeConnection);
        }
        function onUpgradeError() {
            debug("websocket error before upgrade");
            // websocket.close() not needed
        }
    }
    /**
     * Captures upgrade requests for a http.Server.
     *
     * @param {http.Server} server
     * @param {Object} options
     * @api public
     */
    attach(server, options = {}) {
        const path = this._computePath(options);
        const destroyUpgradeTimeout = options.destroyUpgradeTimeout || 1000;
        function check(req) {
            // TODO use `path === new URL(...).pathname` in the next major release (ref: https://nodejs.org/api/url.html)
            return path === req.url.slice(0, path.length);
        }
        // cache and clean up listeners
        const listeners = server.listeners("request").slice(0);
        server.removeAllListeners("request");
        server.on("close", this.close.bind(this));
        server.on("listening", this.init.bind(this));
        // add request handler
        server.on("request", (req, res) => {
            if (check(req)) {
                debug('intercepting request for path "%s"', path);
                this.handleRequest(req, res);
            }
            else {
                let i = 0;
                const l = listeners.length;
                for (; i < l; i++) {
                    listeners[i].call(server, req, res);
                }
            }
        });
        if (~this.opts.transports.indexOf("websocket")) {
            server.on("upgrade", (req, socket, head) => {
                if (check(req)) {
                    this.handleUpgrade(req, socket, head);
                }
                else if (false !== options.destroyUpgrade) {
                    // default node behavior is to disconnect when no handlers
                    // but by adding a handler, we prevent that
                    // and if no eio thing handles the upgrade
                    // then the socket needs to die!
                    setTimeout(function () {
                        // @ts-ignore
                        if (socket.writable && socket.bytesWritten <= 0) {
                            socket.on("error", (e) => {
                                debug("error while destroying upgrade: %s", e.message);
                            });
                            return socket.end();
                        }
                    }, destroyUpgradeTimeout);
                }
            });
        }
    }
}
exports.Server = Server;
/**
 * Close the HTTP long-polling request
 *
 * @param res - the response object
 * @param errorCode - the error code
 * @param errorContext - additional error context
 *
 * @api private
 */
function abortRequest(res, errorCode, errorContext) {
    const statusCode = errorCode === Server.errors.FORBIDDEN ? 403 : 400;
    const message = errorContext && errorContext.message
        ? errorContext.message
        : Server.errorMessages[errorCode];
    res.writeHead(statusCode, { "Content-Type": "application/json" });
    res.end(JSON.stringify({
        code: errorCode,
        message,
    }));
}
/**
 * Close the WebSocket connection
 *
 * @param {net.Socket} socket
 * @param {string} errorCode - the error code
 * @param {object} errorContext - additional error context
 *
 * @api private
 */
function abortUpgrade(socket, errorCode, errorContext = {}) {
    socket.on("error", () => {
        debug("ignoring error from closed connection");
    });
    if (socket.writable) {
        const message = errorContext.message || Server.errorMessages[errorCode];
        const length = Buffer.byteLength(message);
        socket.write("HTTP/1.1 400 Bad Request\r\n" +
            "Connection: close\r\n" +
            "Content-type: text/html\r\n" +
            "Content-Length: " +
            length +
            "\r\n" +
            "\r\n" +
            message);
    }
    socket.destroy();
}
/* eslint-disable */
/**
 * From https://github.com/nodejs/node/blob/v8.4.0/lib/_http_common.js#L303-L354
 *
 * True if val contains an invalid field-vchar
 *  field-value    = *( field-content / obs-fold )
 *  field-content  = field-vchar [ 1*( SP / HTAB ) field-vchar ]
 *  field-vchar    = VCHAR / obs-text
 *
 * checkInvalidHeaderChar() is currently designed to be inlinable by v8,
 * so take care when making changes to the implementation so that the source
 * code size does not exceed v8's default max_inlined_source_size setting.
 **/
// prettier-ignore
const validHdrChars = [
    0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1 // ... 255
];
function checkInvalidHeaderChar(val) {
    val += "";
    if (val.length < 1)
        return false;
    if (!validHdrChars[val.charCodeAt(0)]) {
        debug('invalid header, index 0, char "%s"', val.charCodeAt(0));
        return true;
    }
    if (val.length < 2)
        return false;
    if (!validHdrChars[val.charCodeAt(1)]) {
        debug('invalid header, index 1, char "%s"', val.charCodeAt(1));
        return true;
    }
    if (val.length < 3)
        return false;
    if (!validHdrChars[val.charCodeAt(2)]) {
        debug('invalid header, index 2, char "%s"', val.charCodeAt(2));
        return true;
    }
    if (val.length < 4)
        return false;
    if (!validHdrChars[val.charCodeAt(3)]) {
        debug('invalid header, index 3, char "%s"', val.charCodeAt(3));
        return true;
    }
    for (let i = 4; i < val.length; ++i) {
        if (!validHdrChars[val.charCodeAt(i)]) {
            debug('invalid header, index "%i", char "%s"', i, val.charCodeAt(i));
            return true;
        }
    }
    return false;
}
