chore(release): 4.3.2

Diff: https://github.com/socketio/socket.io/compare/4.3.1...4.3.2

.github/workflows/ci.yml

@@ -12,12 +12,12 @@ jobs:
 
     strategy:
       matrix:
-        node-version: [10.x, 12.x, 14.x, 15.x]
+        node-version: [12, 14, 16]
 
     steps:
       - uses: actions/checkout@v2
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v1
+        uses: actions/setup-node@v2
         with:
           node-version: ${{ matrix.node-version }}
       - run: npm ci

CHANGELOG.md

@@ -1,3 +1,89 @@
+## [4.3.2](https://github.com/socketio/socket.io/compare/4.3.1...4.3.2) (2021-11-08)
+
+
+### Bug Fixes
+
+* fix race condition in dynamic namespaces ([#4137](https://github.com/socketio/socket.io/issues/4137)) ([9d86397](https://github.com/socketio/socket.io/commit/9d86397243bcbb5775a29d96e5ef03e17148a8e7))
+
+
+## [4.3.1](https://github.com/socketio/socket.io/compare/4.3.0...4.3.1) (2021-10-16)
+
+
+### Bug Fixes
+
+* fix server attachment ([#4127](https://github.com/socketio/socket.io/issues/4127)) ([0ef2a4d](https://github.com/socketio/socket.io/commit/0ef2a4d02c9350aff163df9cb61aece89c4dac0f))
+
+
+# [4.3.0](https://github.com/socketio/socket.io/compare/4.2.0...4.3.0) (2021-10-14)
+
+
+### Bug Fixes
+
+* **typings:** add name field to cookie option ([#4099](https://github.com/socketio/socket.io/issues/4099)) ([033c5d3](https://github.com/socketio/socket.io/commit/033c5d399a2b985afad32c1e4b0c16d764e248cd))
+* send volatile packets with binary attachments ([dc81fcf](https://github.com/socketio/socket.io/commit/dc81fcf461cfdbb5b34b1a5a96b84373754047d5))
+
+
+### Features
+
+* serve ESM bundle ([60edecb](https://github.com/socketio/socket.io/commit/60edecb3bd33801803cdcba0aefbafa381a2abb3))
+
+
+# [4.2.0](https://github.com/socketio/socket.io/compare/4.1.3...4.2.0) (2021-08-30)
+
+
+### Bug Fixes
+
+* **typings:** allow async listener in typed events ([ccfd8ca](https://github.com/socketio/socket.io/commit/ccfd8caba6d38b7ba6c5114bd8179346ed07671c))
+
+
+### Features
+
+* ignore the query string when serving client JavaScript ([#4024](https://github.com/socketio/socket.io/issues/4024)) ([24fee27](https://github.com/socketio/socket.io/commit/24fee27ba36485308f8e995879c10931532c814e))
+
+
+## [4.1.3](https://github.com/socketio/socket.io/compare/4.1.2...4.1.3) (2021-07-10)
+
+
+### Bug Fixes
+
+* fix io.except() method ([94e27cd](https://github.com/socketio/socket.io/commit/94e27cd072c8a4eeb9636f6ffbb7a21d382f36b0))
+* remove x-sourcemap header ([a4dffc6](https://github.com/socketio/socket.io/commit/a4dffc6527f412d51a786ae5bf2e9080fe1ca63c))
+
+
+## [4.1.2](https://github.com/socketio/socket.io/compare/4.1.1...4.1.2) (2021-05-17)
+
+
+### Bug Fixes
+
+* **typings:** ensure compatibility with TypeScript 3.x ([0cb6ac9](https://github.com/socketio/socket.io/commit/0cb6ac95b49a27483b6f1b6402fa54b35f82e36f))
+* ensure compatibility with previous versions of the adapter ([a2cf248](https://github.com/socketio/socket.io/commit/a2cf2486c366cb62293101c10520c57f6984a3fc))
+
+
+## [4.1.1](https://github.com/socketio/socket.io/compare/4.1.0...4.1.1) (2021-05-11)
+
+
+### Bug Fixes
+
+* **typings:** properly type server-side events ([b84ed1e](https://github.com/socketio/socket.io/commit/b84ed1e41c9053792caf58974c5de9395bfd509f))
+* **typings:** properly type the adapter attribute ([891b187](https://github.com/socketio/socket.io/commit/891b1870e92d1ec38910f03bb839817e2d6be65a))
+
+
+# [4.1.0](https://github.com/socketio/socket.io/compare/4.0.2...4.1.0) (2021-05-11)
+
+
+### Features
+
+* add support for inter-server communication ([93cce05](https://github.com/socketio/socket.io/commit/93cce05fb3faf91f21fa71212275c776aa161107))
+* notify upon namespace creation ([499c892](https://github.com/socketio/socket.io/commit/499c89250d2db1ab7725ab2b74840e188c267c46))
+* add a "connection_error" event ([7096e98](https://github.com/socketio/engine.io/commit/7096e98a02295a62c8ea2aa56461d4875887092d), from `engine.io`)
+* add the "initial_headers" and "headers" events ([2527543](https://github.com/socketio/engine.io/commit/252754353a0e88eb036ebb3082e9d6a9a5f497db), from `engine.io`)
+
+
+### Performance Improvements
+
+* add support for the "wsPreEncoded" writing option ([dc381b7](https://github.com/socketio/socket.io/commit/dc381b72c6b2f8172001dedd84116122e4cc95b3))
+
+
 ## [4.0.2](https://github.com/socketio/socket.io/compare/4.0.1...4.0.2) (2021-05-06)
 
 

Readme.md

@@ -1,5 +1,5 @@
 # socket.io
-[![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://repl.it/github/socketio/socket.io)
+[![Run on Repl.it](https://repl.it/badge/github/socketio/socket.io)](https://replit.com/@socketio/socketio-minimal-example)
 [![Backers on Open Collective](https://opencollective.com/socketio/backers/badge.svg)](#backers) [![Sponsors on Open Collective](https://opencollective.com/socketio/sponsors/badge.svg)](#sponsors)
 [![Build Status](https://github.com/socketio/socket.io/workflows/CI/badge.svg)](https://github.com/socketio/socket.io/actions)
 [![Dependency Status](https://david-dm.org/socketio/socket.io.svg)](https://david-dm.org/socketio/socket.io)
@@ -22,7 +22,7 @@ Some implementations in other languages are also available:
 - [Swift](https://github.com/socketio/socket.io-client-swift)
 - [Dart](https://github.com/rikulo/socket.io-client-dart)
 - [Python](https://github.com/miguelgrinberg/python-socketio)
-- [.Net](https://github.com/Quobject/SocketIoClientDotNet)
+- [.NET](https://github.com/doghappy/socket.io-client-csharp)
 
 Its main features are:
 

examples/basic-crud-application/server/package.json

@@ -24,6 +24,7 @@
     "uuid": "^8.3.2"
   },
   "devDependencies": {
+    "@types/mocha": "^8.2.3",
     "@types/chai": "^4.2.16",
     "@types/uuid": "^8.3.0",
     "chai": "^4.3.4",

examples/webpack-build-server/index.js

@@ -0,0 +1,20 @@
+const { Server } = require("socket.io");
+
+const clientFile = require("./node_modules/socket.io/client-dist/socket.io.min?raw");
+const clientMap = require("./node_modules/socket.io/client-dist/socket.io.min.js.map?raw");
+
+Server.sendFile = (filename, req, res) => {
+  res.end(filename.endsWith(".map") ? clientMap : clientFile);
+};
+
+const io = new Server();
+
+io.on("connection", socket => {
+  console.log(`connect ${socket.id}`);
+
+  socket.on("disconnect", (reason) => {
+    console.log(`disconnect ${socket.id} due to ${reason}`);
+  });
+});
+
+io.listen(3000);

examples/webpack-build-server/lib/index.js

@@ -1,15 +0,0 @@
-
-const server = require('http').createServer();
-const io = require('socket.io')(server, {
-  serveClient: false
-});
-const port = process.env.PORT || 3000;
-
-io.on('connect', onConnect);
-server.listen(port, () => console.log('server listening on port ' + port));
-
-function onConnect(socket){
-  console.log('connect ' + socket.id);
-
-  socket.on('disconnect', () => console.log('disconnect ' + socket.id));
-}

examples/webpack-build-server/package.json

@@ -4,13 +4,15 @@
   "description": "A sample Webpack build (for the server)",
   "scripts": {
     "start": "node dist/server.js",
-    "build": "webpack --config ./support/webpack.config.js"
+    "build": "webpack"
   },
   "author": "Damien Arrachequesne",
   "license": "MIT",
   "devDependencies": {
+    "bufferutil": "^4.0.3",
     "socket.io": "^4.0.0",
-    "webpack": "~4.43.0",
-    "webpack-cli": "~3.3.11"
+    "utf-8-validate": "^5.0.5",
+    "webpack": "^5.39.0",
+    "webpack-cli": "^4.7.2"
   }
 }

examples/webpack-build-server/support/webpack.config.js

@@ -1,10 +0,0 @@
-
-module.exports = {
-  entry: './lib/index.js',
-  target: 'node',
-  output: {
-    path: require('path').join(__dirname, '../dist'),
-    filename: 'server.js'
-  },
-  mode: 'production'
-};

examples/webpack-build-server/webpack.config.js

@@ -0,0 +1,19 @@
+const path = require("path");
+
+module.exports = {
+  entry: "./index.js",
+  target: "node",
+  mode: "production",
+  output: {
+    path: path.resolve(__dirname, "dist"),
+    filename: "index.js",
+  },
+  module: {
+    rules: [
+      {
+        resourceQuery: /raw/,
+        type: "asset/source",
+      },
+    ],
+  },
+};

lib/broadcast-operator.ts

@@ -10,7 +10,8 @@ import type {
 } from "./typed-events";
 
 export class BroadcastOperator<EmitEvents extends EventsMap>
-  implements TypedEventBroadcaster<EmitEvents> {
+  implements TypedEventBroadcaster<EmitEvents>
+{
   constructor(
     private readonly adapter: Adapter,
     private readonly rooms: Set<Room> = new Set<Room>(),
@@ -186,7 +187,7 @@ export class BroadcastOperator<EmitEvents extends EventsMap>
         return sockets.map((socket) => {
           if (socket instanceof Socket) {
             // FIXME the TypeScript compiler complains about missing private properties
-            return (socket as unknown) as RemoteSocket<EmitEvents>;
+            return socket as unknown as RemoteSocket<EmitEvents>;
           } else {
             return new RemoteSocket(this.adapter, socket as SocketDetails);
           }
@@ -257,7 +258,8 @@ interface SocketDetails {
  * Expose of subset of the attributes and methods of the Socket class
  */
 export class RemoteSocket<EmitEvents extends EventsMap>
-  implements TypedEventBroadcaster<EmitEvents> {
+  implements TypedEventBroadcaster<EmitEvents>
+{
   public readonly id: SocketId;
   public readonly handshake: Handshake;
   public readonly rooms: Set<Room>;

lib/client.ts

@@ -7,21 +7,36 @@ import type { Namespace } from "./namespace";
 import type { EventsMap } from "./typed-events";
 import type { Socket } from "./socket";
 import type { SocketId } from "socket.io-adapter";
+import type { Socket as RawSocket } from "engine.io";
 
 const debug = debugModule("socket.io:client");
 
+interface WriteOptions {
+  compress?: boolean;
+  volatile?: boolean;
+  preEncoded?: boolean;
+  wsPreEncoded?: string;
+}
+
 export class Client<
   ListenEvents extends EventsMap,
-  EmitEvents extends EventsMap
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap
 > {
-  public readonly conn;
+  public readonly conn: RawSocket;
 
   private readonly id: string;
-  private readonly server: Server<ListenEvents, EmitEvents>;
+  private readonly server: Server<ListenEvents, EmitEvents, ServerSideEvents>;
   private readonly encoder: Encoder;
   private readonly decoder: Decoder;
-  private sockets: Map<SocketId, Socket<ListenEvents, EmitEvents>> = new Map();
-  private nsps: Map<string, Socket<ListenEvents, EmitEvents>> = new Map();
+  private sockets: Map<
+    SocketId,
+    Socket<ListenEvents, EmitEvents, ServerSideEvents>
+  > = new Map();
+  private nsps: Map<
+    string,
+    Socket<ListenEvents, EmitEvents, ServerSideEvents>
+  > = new Map();
   private connectTimeout?: NodeJS.Timeout;
 
   /**
@@ -31,7 +46,10 @@ export class Client<
    * @param conn
    * @package
    */
-  constructor(server: Server<ListenEvents, EmitEvents>, conn: any) {
+  constructor(
+    server: Server<ListenEvents, EmitEvents, ServerSideEvents>,
+    conn: any
+  ) {
     this.server = server;
     this.conn = conn;
     this.encoder = server.encoder;
@@ -92,9 +110,12 @@ export class Client<
     this.server._checkNamespace(
       name,
       auth,
-      (dynamicNspName: Namespace<ListenEvents, EmitEvents> | false) => {
+      (
+        dynamicNspName:
+          | Namespace<ListenEvents, EmitEvents, ServerSideEvents>
+          | false
+      ) => {
         if (dynamicNspName) {
-          debug("dynamic namespace %s was created", dynamicNspName);
           this.doConnect(name, auth);
         } else {
           debug("creation of namespace %s was denied", name);
@@ -150,7 +171,7 @@ export class Client<
    *
    * @private
    */
-  _remove(socket: Socket<ListenEvents, EmitEvents>): void {
+  _remove(socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>): void {
     if (this.sockets.has(socket.id)) {
       const nsp = this.sockets.get(socket.id)!.nsp.name;
       this.sockets.delete(socket.id);
@@ -180,30 +201,32 @@ export class Client<
    * @param {Object} opts
    * @private
    */
-  _packet(packet: Packet, opts?: any): void {
-    opts = opts || {};
-    const self = this;
-
-    // this writes to the actual connection
-    function writeToEngine(encodedPackets: any) {
-      // TODO clarify this.
-      if (opts.volatile && !self.conn.transport.writable) return;
-      for (let i = 0; i < encodedPackets.length; i++) {
-        self.conn.write(encodedPackets[i], { compress: opts.compress });
-      }
-    }
-
-    if ("open" === this.conn.readyState) {
-      debug("writing packet %j", packet);
-      if (!opts.preEncoded) {
-        // not broadcasting, need to encode
-        writeToEngine(this.encoder.encode(packet)); // encode, then write results to engine
-      } else {
-        // a broadcast pre-encodes a packet
-        writeToEngine(packet);
-      }
-    } else {
+  _packet(packet: Packet | any[], opts: WriteOptions = {}): void {
+    if (this.conn.readyState !== "open") {
       debug("ignoring packet write %j", packet);
+      return;
+    }
+    const encodedPackets = opts.preEncoded
+      ? (packet as any[]) // previous versions of the adapter incorrectly used socket.packet() instead of writeToEngine()
+      : this.encoder.encode(packet as Packet);
+    this.writeToEngine(encodedPackets, opts);
+  }
+
+  private writeToEngine(
+    encodedPackets: Array<String | Buffer>,
+    opts: WriteOptions
+  ): void {
+    if (opts.volatile && !this.conn.transport.writable) {
+      debug(
+        "volatile packet is discarded since the transport is not currently writable"
+      );
+      return;
+    }
+    const packets = Array.isArray(encodedPackets)
+      ? encodedPackets
+      : [encodedPackets];
+    for (const encodedPacket of packets) {
+      this.conn.write(encodedPacket, opts);
     }
   }
 

lib/index.ts

@@ -4,28 +4,28 @@ import { createDeflate, createGzip, createBrotliCompress } from "zlib";
 import accepts = require("accepts");
 import { pipeline } from "stream";
 import path = require("path");
-import engine = require("engine.io");
+import {
+  attach,
+  Server as Engine,
+  ServerOptions as EngineOptions,
+  AttachOptions,
+} from "engine.io";
 import { Client } from "./client";
 import { EventEmitter } from "events";
-import {
-  ExtendedError,
-  Namespace,
-  NamespaceReservedEventsMap,
-} from "./namespace";
+import { ExtendedError, Namespace, ServerReservedEventsMap } from "./namespace";
 import { ParentNamespace } from "./parent-namespace";
 import { Adapter, Room, SocketId } from "socket.io-adapter";
 import * as parser from "socket.io-parser";
 import type { Encoder } from "socket.io-parser";
 import debugModule from "debug";
 import { Socket } from "./socket";
-import type { CookieSerializeOptions } from "cookie";
-import type { CorsOptions } from "cors";
 import type { BroadcastOperator, RemoteSocket } from "./broadcast-operator";
 import {
   EventsMap,
   DefaultEventsMap,
   EventParams,
   StrictEventEmitter,
+  EventNames,
 } from "./typed-events";
 
 const debug = debugModule("socket.io:server");
@@ -33,114 +33,15 @@ const debug = debugModule("socket.io:server");
 const clientVersion = require("../package.json").version;
 const dotMapRegex = /\.map/;
 
-type Transport = "polling" | "websocket";
 type ParentNspNameMatchFn = (
   name: string,
   auth: { [key: string]: any },
   fn: (err: Error | null, success: boolean) => void
 ) => void;
 
-interface EngineOptions {
-  /**
-   * how many ms without a pong packet to consider the connection closed
-   * @default 20000
-   */
-  pingTimeout: number;
-  /**
-   * how many ms before sending a new ping packet
-   * @default 25000
-   */
-  pingInterval: number;
-  /**
-   * how many ms before an uncompleted transport upgrade is cancelled
-   * @default 10000
-   */
-  upgradeTimeout: number;
-  /**
-   * how many bytes or characters a message can be, before closing the session (to avoid DoS).
-   * @default 1e5 (100 KB)
-   */
-  maxHttpBufferSize: number;
-  /**
-   * A function that receives a given handshake or upgrade request as its first parameter,
-   * and can decide whether to continue or not. The second argument is a function that needs
-   * to be called with the decided information: fn(err, success), where success is a boolean
-   * value where false means that the request is rejected, and err is an error code.
-   */
-  allowRequest: (
-    req: http.IncomingMessage,
-    fn: (err: string | null | undefined, success: boolean) => void
-  ) => void;
-  /**
-   * the low-level transports that are enabled
-   * @default ["polling", "websocket"]
-   */
-  transports: Transport[];
-  /**
-   * whether to allow transport upgrades
-   * @default true
-   */
-  allowUpgrades: boolean;
-  /**
-   * parameters of the WebSocket permessage-deflate extension (see ws module api docs). Set to false to disable.
-   * @default false
-   */
-  perMessageDeflate: boolean | object;
-  /**
-   * parameters of the http compression for the polling transports (see zlib api docs). Set to false to disable.
-   * @default true
-   */
-  httpCompression: boolean | object;
-  /**
-   * what WebSocket server implementation to use. Specified module must
-   * conform to the ws interface (see ws module api docs).
-   * An alternative c++ addon is also available by installing eiows module.
-   *
-   * @default `require("ws").Server`
-   */
-  wsEngine: Function;
-  /**
-   * an optional packet which will be concatenated to the handshake packet emitted by Engine.IO.
-   */
-  initialPacket: any;
-  /**
-   * configuration of the cookie that contains the client sid to send as part of handshake response headers. This cookie
-   * might be used for sticky-session. Defaults to not sending any cookie.
-   * @default false
-   */
-  cookie: CookieSerializeOptions | boolean;
-  /**
-   * the options that will be forwarded to the cors module
-   */
-  cors: CorsOptions;
-  /**
-   * whether to enable compatibility with Socket.IO v2 clients
-   * @default false
-   */
-  allowEIO3: boolean;
-}
+type AdapterConstructor = typeof Adapter | ((nsp: Namespace) => Adapter);
 
-interface AttachOptions {
-  /**
-   * name of the path to capture
-   * @default "/engine.io"
-   */
-  path: string;
-  /**
-   * destroy unhandled upgrade requests
-   * @default true
-   */
-  destroyUpgrade: boolean;
-  /**
-   * milliseconds after which unhandled requests are ended
-   * @default 1000
-   */
-  destroyUpgradeTimeout: number;
-}
-
-interface EngineAttachOptions extends EngineOptions, AttachOptions {}
-
-interface ServerOptions extends EngineAttachOptions {
+interface ServerOptions extends EngineOptions, AttachOptions {
   /**
    * name of the path to capture
    * @default "/socket.io"
@@ -155,7 +56,7 @@ interface ServerOptions extends EngineAttachOptions {
    * the adapter to use
    * @default the in-memory adapter (https://github.com/socketio/socket.io-adapter)
    */
-  adapter: any;
+  adapter: AdapterConstructor;
   /**
    * the parser to use
    * @default the default parser (https://github.com/socketio/socket.io-parser)
@@ -170,13 +71,18 @@ interface ServerOptions extends EngineAttachOptions {
 
 export class Server<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap
 > extends StrictEventEmitter<
-  {},
+  ServerSideEvents,
   EmitEvents,
-  NamespaceReservedEventsMap<ListenEvents, EmitEvents>
+  ServerReservedEventsMap<ListenEvents, EmitEvents, ServerSideEvents>
 > {
-  public readonly sockets: Namespace<ListenEvents, EmitEvents>;
+  public readonly sockets: Namespace<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents
+  >;
   /**
    * A reference to the underlying Engine.IO server.
    *
@@ -197,15 +103,16 @@ export class Server<
   /**
    * @private
    */
-  _nsps: Map<string, Namespace<ListenEvents, EmitEvents>> = new Map();
+  _nsps: Map<string, Namespace<ListenEvents, EmitEvents, ServerSideEvents>> =
+    new Map();
   private parentNsps: Map<
     ParentNspNameMatchFn,
-    ParentNamespace<ListenEvents, EmitEvents>
+    ParentNamespace<ListenEvents, EmitEvents, ServerSideEvents>
   > = new Map();
-  private _adapter?: typeof Adapter;
+  private _adapter?: AdapterConstructor;
   private _serveClient: boolean;
   private opts: Partial<EngineOptions>;
-  private eio;
+  private eio: Engine;
   private _path: string;
   private clientPathRegex: RegExp;
 
@@ -249,7 +156,7 @@ export class Server<
     this.adapter(opts.adapter || Adapter);
     this.sockets = this.of("/");
     this.opts = opts;
-    if (srv) this.attach(srv as http.Server);
+    if (srv || typeof srv == "number") this.attach(srv as http.Server | number);
   }
 
   /**
@@ -280,7 +187,9 @@ export class Server<
   _checkNamespace(
     name: string,
     auth: { [key: string]: any },
-    fn: (nsp: Namespace<ListenEvents, EmitEvents> | false) => void
+    fn: (
+      nsp: Namespace<ListenEvents, EmitEvents, ServerSideEvents> | false
+    ) => void
   ): void {
     if (this.parentNsps.size === 0) return fn(false);
 
@@ -293,10 +202,18 @@ export class Server<
       }
       nextFn.value(name, auth, (err, allow) => {
         if (err || !allow) {
-          run();
-        } else {
-          fn(this.parentNsps.get(nextFn.value)!.createChild(name));
+          return run();
         }
+        if (this._nsps.has(name)) {
+          // the namespace was created in the meantime
+          debug("dynamic namespace %s already exists", name);
+          return fn(this._nsps.get(name) as Namespace);
+        }
+        const namespace = this.parentNsps.get(nextFn.value)!.createChild(name);
+        debug("dynamic namespace %s was created", name);
+        // @ts-ignore
+        this.sockets.emitReserved("new_namespace", namespace);
+        fn(namespace);
       });
     };
 
@@ -322,7 +239,7 @@ export class Server<
     this.clientPathRegex = new RegExp(
       "^" +
         escapedPath +
-        "/socket\\.io(\\.min|\\.msgpack\\.min)?\\.js(\\.map)?$"
+        "/socket\\.io(\\.msgpack|\\.esm)?(\\.min)?\\.js(\\.map)?(?:\\?|$)"
     );
     return this;
   }
@@ -348,10 +265,11 @@ export class Server<
    * @return self when setting or value when getting
    * @public
    */
-  public adapter(): typeof Adapter | undefined;
-  public adapter(v: typeof Adapter): this;
-  public adapter(v?: typeof Adapter): typeof Adapter | undefined | this;
-  public adapter(v?: typeof Adapter): typeof Adapter | undefined | this {
+  public adapter(): AdapterConstructor | undefined;
+  public adapter(v: AdapterConstructor): this;
+  public adapter(
+    v?: AdapterConstructor
+  ): AdapterConstructor | undefined | this {
     if (!arguments.length) return this._adapter;
     this._adapter = v;
     for (const nsp of this._nsps.values()) {
@@ -428,11 +346,11 @@ export class Server<
    */
   private initEngine(
     srv: http.Server,
-    opts: Partial<EngineAttachOptions>
+    opts: EngineOptions & AttachOptions
   ): void {
     // initialize engine
     debug("creating engine.io instance with opts %j", opts);
-    this.eio = engine.attach(srv, opts);
+    this.eio = attach(srv, opts);
 
     // attach static file serving
     if (this._serveClient) this.attachServe(srv);
@@ -456,7 +374,7 @@ export class Server<
     const evs = srv.listeners("request").slice(0);
     srv.removeAllListeners("request");
     srv.on("request", (req, res) => {
-      if (this.clientPathRegex.test(req.url)) {
+      if (this.clientPathRegex.test(req.url!)) {
         this.serve(req, res);
       } else {
         for (let i = 0; i < evs.length; i++) {
@@ -474,7 +392,7 @@ export class Server<
    * @private
    */
   private serve(req: http.IncomingMessage, res: http.ServerResponse): void {
-    const filename = req.url!.replace(this._path, "");
+    const filename = req.url!.replace(this._path, "").replace(/\?.*$/, "");
     const isMap = dotMapRegex.test(filename);
     const type = isMap ? "map" : "source";
 
@@ -502,9 +420,6 @@ export class Server<
     );
     res.setHeader("ETag", expectedEtag);
 
-    if (!isMap) {
-      res.setHeader("X-SourceMap", filename.substring(1) + ".map");
-    }
     Server.sendFile(filename, req, res);
   }
 
@@ -589,8 +504,8 @@ export class Server<
    */
   public of(
     name: string | RegExp | ParentNspNameMatchFn,
-    fn?: (socket: Socket<ListenEvents, EmitEvents>) => void
-  ): Namespace<ListenEvents, EmitEvents> {
+    fn?: (socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>) => void
+  ): Namespace<ListenEvents, EmitEvents, ServerSideEvents> {
     if (typeof name === "function" || name instanceof RegExp) {
       const parentNsp = new ParentNamespace(this);
       debug("initializing parent namespace %s", parentNsp.name);
@@ -616,6 +531,10 @@ export class Server<
       debug("initializing namespace %s", name);
       nsp = new Namespace(this, name);
       this._nsps.set(name, nsp);
+      if (name !== "/") {
+        // @ts-ignore
+        this.sockets.emitReserved("new_namespace", nsp);
+      }
     }
     if (fn) nsp.on("connect", fn);
     return nsp;
@@ -649,7 +568,7 @@ export class Server<
    */
   public use(
     fn: (
-      socket: Socket<ListenEvents, EmitEvents>,
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>,
       next: (err?: ExtendedError) => void
     ) => void
   ): this {
@@ -686,9 +605,8 @@ export class Server<
    * @return self
    * @public
    */
-  public except(name: Room | Room[]): Server<ListenEvents, EmitEvents> {
-    this.sockets.except(name);
-    return this;
+  public except(name: Room | Room[]): BroadcastOperator<EmitEvents> {
+    return this.sockets.except(name);
   }
 
   /**
@@ -713,6 +631,20 @@ export class Server<
     return this;
   }
 
+  /**
+   * Emit a packet to other Socket.IO servers
+   *
+   * @param ev - the event name
+   * @param args - an array of arguments, which may include an acknowledgement callback at the end
+   * @public
+   */
+  public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: EventParams<ServerSideEvents, Ev>
+  ): boolean {
+    return this.sockets.serverSideEmit(ev, ...args);
+  }
+
   /**
    * Gets a list of socket ids.
    *

lib/namespace.ts

@@ -20,35 +20,57 @@ export interface ExtendedError extends Error {
 
 export interface NamespaceReservedEventsMap<
   ListenEvents extends EventsMap,
-  EmitEvents extends EventsMap
+  EmitEvents extends EventsMap,
+  ServerSideEvents extends EventsMap
 > {
-  connect: (socket: Socket<ListenEvents, EmitEvents>) => void;
-  connection: (socket: Socket<ListenEvents, EmitEvents>) => void;
+  connect: (socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>) => void;
+  connection: (
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>
+  ) => void;
 }
 
+export interface ServerReservedEventsMap<
+  ListenEvents,
+  EmitEvents,
+  ServerSideEvents
+> extends NamespaceReservedEventsMap<
+    ListenEvents,
+    EmitEvents,
+    ServerSideEvents
+  > {
+  new_namespace: (
+    namespace: Namespace<ListenEvents, EmitEvents, ServerSideEvents>
+  ) => void;
+}
+
+export const RESERVED_EVENTS: ReadonlySet<string | Symbol> = new Set<
+  keyof ServerReservedEventsMap<never, never, never>
+>(<const>["connect", "connection", "new_namespace"]);
+
 export class Namespace<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap
 > extends StrictEventEmitter<
-  {},
+  ServerSideEvents,
   EmitEvents,
-  NamespaceReservedEventsMap<ListenEvents, EmitEvents>
+  NamespaceReservedEventsMap<ListenEvents, EmitEvents, ServerSideEvents>
 > {
   public readonly name: string;
   public readonly sockets: Map<
     SocketId,
-    Socket<ListenEvents, EmitEvents>
+    Socket<ListenEvents, EmitEvents, ServerSideEvents>
   > = new Map();
 
   public adapter: Adapter;
 
   /** @private */
-  readonly server: Server<ListenEvents, EmitEvents>;
+  readonly server: Server<ListenEvents, EmitEvents, ServerSideEvents>;
 
   /** @private */
   _fns: Array<
     (
-      socket: Socket<ListenEvents, EmitEvents>,
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>,
       next: (err?: ExtendedError) => void
     ) => void
   > = [];
@@ -62,7 +84,10 @@ export class Namespace<
    * @param server instance
    * @param name
    */
-  constructor(server: Server<ListenEvents, EmitEvents>, name: string) {
+  constructor(
+    server: Server<ListenEvents, EmitEvents, ServerSideEvents>,
+    name: string
+  ) {
     super();
     this.server = server;
     this.name = name;
@@ -77,6 +102,7 @@ export class Namespace<
    * @private
    */
   _initAdapter(): void {
+    // @ts-ignore
     this.adapter = new (this.server.adapter()!)(this);
   }
 
@@ -88,7 +114,7 @@ export class Namespace<
    */
   public use(
     fn: (
-      socket: Socket<ListenEvents, EmitEvents>,
+      socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>,
       next: (err?: ExtendedError) => void
     ) => void
   ): this {
@@ -104,7 +130,7 @@ export class Namespace<
    * @private
    */
   private run(
-    socket: Socket<ListenEvents, EmitEvents>,
+    socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>,
     fn: (err: ExtendedError | null) => void
   ) {
     const fns = this._fns.slice(0);
@@ -166,10 +192,10 @@ export class Namespace<
    * @private
    */
   _add(
-    client: Client<ListenEvents, EmitEvents>,
+    client: Client<ListenEvents, EmitEvents, ServerSideEvents>,
     query,
     fn?: () => void
-  ): Socket<ListenEvents, EmitEvents> {
+  ): Socket<ListenEvents, EmitEvents, ServerSideEvents> {
     debug("adding socket to nsp %s", this.name);
     const socket = new Socket(this, client, query);
     this.run(socket, (err) => {
@@ -212,7 +238,7 @@ export class Namespace<
    *
    * @private
    */
-  _remove(socket: Socket<ListenEvents, EmitEvents>): void {
+  _remove(socket: Socket<ListenEvents, EmitEvents, ServerSideEvents>): void {
     if (this.sockets.has(socket.id)) {
       this.sockets.delete(socket.id);
     } else {
@@ -255,6 +281,36 @@ export class Namespace<
     return this;
   }
 
+  /**
+   * Emit a packet to other Socket.IO servers
+   *
+   * @param ev - the event name
+   * @param args - an array of arguments, which may include an acknowledgement callback at the end
+   * @public
+   */
+  public serverSideEmit<Ev extends EventNames<ServerSideEvents>>(
+    ev: Ev,
+    ...args: EventParams<ServerSideEvents, Ev>
+  ): boolean {
+    if (RESERVED_EVENTS.has(ev)) {
+      throw new Error(`"${ev}" is a reserved event name`);
+    }
+    args.unshift(ev);
+    this.adapter.serverSideEmit(args);
+    return true;
+  }
+
+  /**
+   * Called when a packet is received from another Socket.IO server
+   *
+   * @param args - an array of arguments, which may include an acknowledgement callback at the end
+   *
+   * @private
+   */
+  _onServerSideEmit(args: [string, ...any[]]) {
+    super.emitUntyped.apply(this, args);
+  }
+
   /**
    * Gets a list of clients.
    *

lib/parent-namespace.ts

@@ -10,12 +10,14 @@ import type { BroadcastOptions } from "socket.io-adapter";
 
 export class ParentNamespace<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
-> extends Namespace<ListenEvents, EmitEvents> {
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap
+> extends Namespace<ListenEvents, EmitEvents, ServerSideEvents> {
   private static count: number = 0;
-  private children: Set<Namespace<ListenEvents, EmitEvents>> = new Set();
+  private children: Set<Namespace<ListenEvents, EmitEvents, ServerSideEvents>> =
+    new Set();
 
-  constructor(server: Server<ListenEvents, EmitEvents>) {
+  constructor(server: Server<ListenEvents, EmitEvents, ServerSideEvents>) {
     super(server, "/_" + ParentNamespace.count++);
   }
 
@@ -43,7 +45,9 @@ export class ParentNamespace<
     return true;
   }
 
-  createChild(name: string): Namespace<ListenEvents, EmitEvents> {
+  createChild(
+    name: string
+  ): Namespace<ListenEvents, EmitEvents, ServerSideEvents> {
     const namespace = new Namespace(this.server, name);
     namespace._fns = this._fns.slice(0);
     this.listeners("connect").forEach((listener) =>

lib/socket.ts

@@ -46,7 +46,7 @@ export interface EventEmitterReservedEventsMap {
 
 export const RESERVED_EVENTS: ReadonlySet<string | Symbol> = new Set<
   | ClientReservedEvents
-  | keyof NamespaceReservedEventsMap<never, never>
+  | keyof NamespaceReservedEventsMap<never, never, never>
   | keyof SocketReservedEventsMap
   | keyof EventEmitterReservedEventsMap
 >(<const>[
@@ -108,9 +108,12 @@ export interface Handshake {
   auth: { [key: string]: any };
 }
 
+type Event = [eventName: string, ...args: any[]];
+
 export class Socket<
   ListenEvents extends EventsMap = DefaultEventsMap,
-  EmitEvents extends EventsMap = ListenEvents
+  EmitEvents extends EventsMap = ListenEvents,
+  ServerSideEvents extends EventsMap = DefaultEventsMap
 > extends StrictEventEmitter<
   ListenEvents,
   EmitEvents,
@@ -126,12 +129,10 @@ export class Socket<
   public connected: boolean;
   public disconnected: boolean;
 
-  private readonly server: Server<ListenEvents, EmitEvents>;
+  private readonly server: Server<ListenEvents, EmitEvents, ServerSideEvents>;
   private readonly adapter: Adapter;
   private acks: Map<number, () => void> = new Map();
-  private fns: Array<
-    (event: Array<any>, next: (err?: Error) => void) => void
-  > = [];
+  private fns: Array<(event: Event, next: (err?: Error) => void) => void> = [];
   private flags: BroadcastFlags = {};
   private _anyListeners?: Array<(...args: any[]) => void>;
 
@@ -144,8 +145,8 @@ export class Socket<
    * @package
    */
   constructor(
-    readonly nsp: Namespace<ListenEvents, EmitEvents>,
-    readonly client: Client<ListenEvents, EmitEvents>,
+    readonly nsp: Namespace<ListenEvents, EmitEvents, ServerSideEvents>,
+    readonly client: Client<ListenEvents, EmitEvents, ServerSideEvents>,
     auth: object
   ) {
     super();
@@ -569,7 +570,7 @@ export class Socket<
    * @param {Array} event - event that will get emitted
    * @private
    */
-  private dispatch(event: [eventName: string, ...args: any[]]): void {
+  private dispatch(event: Event): void {
     debug("dispatching an event %j", event);
     this.run(event, (err) => {
       process.nextTick(() => {
@@ -592,9 +593,7 @@ export class Socket<
    * @return {Socket} self
    * @public
    */
-  public use(
-    fn: (event: Array<any>, next: (err?: Error) => void) => void
-  ): this {
+  public use(fn: (event: Event, next: (err?: Error) => void) => void): this {
     this.fns.push(fn);
     return this;
   }
@@ -606,10 +605,7 @@ export class Socket<
    * @param {Function} fn - last fn call in the middleware
    * @private
    */
-  private run(
-    event: [eventName: string, ...args: any[]],
-    fn: (err: Error | null) => void
-  ): void {
+  private run(event: Event, fn: (err: Error | null) => void): void {
     const fns = this.fns.slice(0);
     if (!fns.length) return fn(null);
 

lib/typed-events.ts

@@ -58,7 +58,7 @@ export type ReservedOrUserListener<
  * Needed because of https://github.com/microsoft/TypeScript/issues/41778
  */
 type FallbackToUntypedListener<T> = [T] extends [never]
-  ? (...args: any[]) => void
+  ? (...args: any[]) => void | Promise<void>
   : T;
 
 /**
@@ -91,7 +91,8 @@ export abstract class StrictEventEmitter<
     ReservedEvents extends EventsMap = {}
   >
   extends EventEmitter
-  implements TypedEventBroadcaster<EmitEvents> {
+  implements TypedEventBroadcaster<EmitEvents>
+{
   /**
    * Adds the `listener` function as an event listener for `ev`.
    *

package.json

@@ -1,6 +1,6 @@
 {
   "name": "socket.io",
-  "version": "4.0.2",
+  "version": "4.3.2",
   "description": "node.js realtime framework server",
   "keywords": [
     "realtime",
@@ -45,33 +45,27 @@
     "prepack": "npm run compile"
   },
   "dependencies": {
-    "@types/cookie": "^0.4.0",
-    "@types/cors": "^2.8.8",
-    "@types/node": ">=10.0.0",
     "accepts": "~1.3.4",
     "base64id": "~2.0.0",
-    "debug": "~4.3.1",
-    "engine.io": "~5.0.0",
-    "socket.io-adapter": "~2.2.0",
-    "socket.io-parser": "~4.0.3"
+    "debug": "~4.3.2",
+    "engine.io": "~6.0.0",
+    "socket.io-adapter": "~2.3.2",
+    "socket.io-parser": "~4.0.4"
   },
   "devDependencies": {
-    "@types/mocha": "^8.0.4",
-    "babel-eslint": "^10.1.0",
-    "eslint": "^7.14.0",
-    "eslint-config-prettier": "^6.11.0",
+    "@types/mocha": "^9.0.0",
     "expect.js": "0.3.1",
     "mocha": "^3.5.3",
     "nyc": "^15.1.0",
-    "prettier": "^2.2.0",
+    "prettier": "^2.3.2",
     "rimraf": "^3.0.2",
-    "socket.io-client": "4.0.2",
+    "socket.io-client": "4.3.2",
     "socket.io-client-v2": "npm:socket.io-client@^2.4.0",
     "superagent": "^6.1.0",
-    "supertest": "^6.0.1",
-    "ts-node": "^9.0.0",
-    "tsd": "^0.14.0",
-    "typescript": "^4.1.2"
+    "supertest": "^6.1.6",
+    "ts-node": "^10.2.1",
+    "tsd": "^0.17.0",
+    "typescript": "^4.4.2"
   },
   "contributors": [
     {

test/fixtures/server-close.ts

@@ -3,7 +3,7 @@ const ioc = require("socket.io-client");
 const io = require("../..")(server);
 
 const srv = server.listen(() => {
-  const socket = ioc("ws://localhost:" + server.address().port);
+  const socket = ioc.connect("ws://localhost:" + server.address().port);
   socket.on("connect", () => {
     io.close();
     socket.close();

test/socket.io.test-d.ts

@@ -1,8 +1,9 @@
 "use strict";
-import { Server, Socket } from "..";
+import { Namespace, Server, Socket } from "..";
 import type { DefaultEventsMap } from "../lib/typed-events";
 import { createServer } from "http";
 import { expectError, expectType } from "tsd";
+import { Adapter } from "socket.io-adapter";
 
 // This file is run by tsd, not mocha.
 
@@ -117,7 +118,9 @@ describe("server", () => {
 
       it("does not accept arguments of wrong types", (done) => {
         const srv = createServer();
-        const sio = new Server<BidirectionalEvents>(srv);
+        const sio = new Server<BidirectionalEvents, BidirectionalEvents, {}>(
+          srv
+        );
         expectError(sio.on("random", (a, b, c) => {}));
         srv.listen(() => {
           expectError(sio.on("wrong name", (s) => {}));
@@ -229,4 +232,69 @@ describe("server", () => {
       });
     });
   });
+
+  describe("listen and emit event maps", () => {
+    interface ClientToServerEvents {
+      helloFromClient: (message: string) => void;
+    }
+
+    interface ServerToClientEvents {
+      helloFromServer: (message: string, x: number) => void;
+    }
+
+    interface InterServerEvents {
+      helloFromServerToServer: (message: string, x: number) => void;
+    }
+
+    describe("on", () => {
+      it("infers correct types for listener parameters", () => {
+        const srv = createServer();
+        const sio = new Server<
+          ClientToServerEvents,
+          ServerToClientEvents,
+          InterServerEvents
+        >(srv);
+
+        expectType<
+          Server<ClientToServerEvents, ServerToClientEvents, InterServerEvents>
+        >(sio);
+        srv.listen(() => {
+          sio.serverSideEmit("helloFromServerToServer", "hello", 10);
+          sio
+            .of("/test")
+            .serverSideEmit("helloFromServerToServer", "hello", 10);
+
+          sio.on("helloFromServerToServer", (message, x) => {
+            expectType<string>(message);
+            expectType<number>(x);
+          });
+          sio.of("/test").on("helloFromServerToServer", (message, x) => {
+            expectType<string>(message);
+            expectType<number>(x);
+          });
+        });
+      });
+    });
+  });
+
+  describe("adapter", () => {
+    it("accepts arguments of the correct types", () => {
+      const io = new Server({
+        adapter: (nsp) => new Adapter(nsp),
+      });
+      io.adapter(Adapter);
+
+      class MyCustomAdapter extends Adapter {
+        constructor(nsp, readonly opts) {
+          super(nsp);
+        }
+      }
+      io.adapter((nsp) => new MyCustomAdapter(nsp, { test: "123" }));
+    });
+
+    it("does not accept arguments of wrong types", () => {
+      const io = new Server();
+      expectError(io.adapter((nsp) => "nope"));
+    });
+  });
 });

test/socket.io.ts

@@ -15,6 +15,8 @@ import { io as ioc, Socket as ClientSocket } from "socket.io-client";
 import "./support/util";
 import "./utility-methods";
 
+type callback = (err: Error | null, success: boolean) => void;
+
 // Creates a socket.io client for the given server
 function client(srv, nsp?: string | object, opts?: object): ClientSocket {
   if ("object" == typeof nsp) {
@@ -39,6 +41,11 @@ const waitFor = (emitter, event) => {
   });
 };
 
+const getPort = (io: Server): number => {
+  // @ts-ignore
+  return io.httpServer.address().port;
+};
+
 describe("socket.io", () => {
   it("should be the same version as client", () => {
     const version = require("../package").version;
@@ -59,7 +66,7 @@ describe("socket.io", () => {
             if (err) return done(err);
             expect(res.headers["content-type"]).to.be("application/javascript");
             expect(res.headers.etag).to.be('"' + clientVersion + '"');
-            expect(res.headers["x-sourcemap"]).to.be(filename + ".map");
+            expect(res.headers["x-sourcemap"]).to.be(undefined);
             expect(res.text).to.match(/engine\.io/);
             expect(res.status).to.be(200);
             done();
@@ -83,6 +90,10 @@ describe("socket.io", () => {
       };
 
       it("should serve client", testSource("socket.io.js"));
+      it(
+        "should serve client with query string",
+        testSource("socket.io.js?buster=" + Date.now())
+      );
       it("should serve source map", testSourceMap("socket.io.js.map"));
       it("should serve client (min)", testSource("socket.io.min.js"));
 
@@ -116,6 +127,13 @@ describe("socket.io", () => {
         testSourceMap("socket.io.msgpack.min.js.map")
       );
 
+      it("should serve the ESM bundle", testSource("socket.io.esm.min.js"));
+
+      it(
+        "should serve the source map for the ESM bundle",
+        testSourceMap("socket.io.esm.min.js.map")
+      );
+
       it("should handle 304", (done) => {
         const srv = createServer();
         new Server(srv);
@@ -185,29 +203,17 @@ describe("socket.io", () => {
 
     describe("port", () => {
       it("should be bound", (done) => {
-        const sockets = new Server(54010);
-        request("http://localhost:54010")
-          .get("/socket.io/socket.io.js")
-          .expect(200, done);
-      });
+        const io = new Server(0);
 
-      it("should be bound as a string", (done) => {
-        const sockets = new Server(54020);
-        request("http://localhost:54020")
+        request(`http://localhost:${getPort(io)}`)
           .get("/socket.io/socket.io.js")
           .expect(200, done);
       });
 
       it("with listen", (done) => {
-        const sockets = new Server().listen(54011);
-        request("http://localhost:54011")
-          .get("/socket.io/socket.io.js")
-          .expect(200, done);
-      });
+        const io = new Server().listen(0);
 
-      it("as a string", (done) => {
-        const sockets = new Server().listen(54012);
-        request("http://localhost:54012")
+        request(`http://localhost:${getPort(io)}`)
           .get("/socket.io/socket.io.js")
           .expect(200, done);
       });
@@ -218,7 +224,7 @@ describe("socket.io", () => {
     const request = require("superagent");
 
     it("should send the Access-Control-Allow-xxx headers on OPTIONS request", (done) => {
-      const sockets = new Server(54013, {
+      const io = new Server(0, {
         cors: {
           origin: "http://localhost:54023",
           methods: ["GET", "POST"],
@@ -227,7 +233,7 @@ describe("socket.io", () => {
         },
       });
       request
-        .options("http://localhost:54013/socket.io/default/")
+        .options(`http://localhost:${getPort(io)}/socket.io/default/`)
         .query({ transport: "polling", EIO: 4 })
         .set("Origin", "http://localhost:54023")
         .end((err, res) => {
@@ -246,7 +252,7 @@ describe("socket.io", () => {
     });
 
     it("should send the Access-Control-Allow-xxx headers on GET request", (done) => {
-      const sockets = new Server(54014, {
+      const io = new Server(0, {
         cors: {
           origin: "http://localhost:54024",
           methods: ["GET", "POST"],
@@ -255,7 +261,7 @@ describe("socket.io", () => {
         },
       });
       request
-        .get("http://localhost:54014/socket.io/default/")
+        .get(`http://localhost:${getPort(io)}/socket.io/default/`)
         .query({ transport: "polling", EIO: 4 })
         .set("Origin", "http://localhost:54024")
         .end((err, res) => {
@@ -270,12 +276,12 @@ describe("socket.io", () => {
     });
 
     it("should allow request if custom function in opts.allowRequest returns true", (done) => {
-      const sockets = new Server(createServer().listen(54022), {
+      const io = new Server(0, {
         allowRequest: (req, callback) => callback(null, true),
       });
 
       request
-        .get("http://localhost:54022/socket.io/default/")
+        .get(`http://localhost:${getPort(io)}/socket.io/default/`)
         .query({ transport: "polling", EIO: 4 })
         .end((err, res) => {
           expect(res.status).to.be(200);
@@ -284,11 +290,11 @@ describe("socket.io", () => {
     });
 
     it("should disallow request if custom function in opts.allowRequest returns false", (done) => {
-      const sockets = new Server(createServer().listen(54023), {
+      const io = new Server(0, {
         allowRequest: (req, callback) => callback(null, false),
       });
       request
-        .get("http://localhost:54023/socket.io/default/")
+        .get(`http://localhost:${getPort(io)}/socket.io/default/`)
         .set("origin", "http://foo.example")
         .query({ transport: "polling", EIO: 4 })
         .end((err, res) => {
@@ -300,22 +306,22 @@ describe("socket.io", () => {
 
   describe("close", () => {
     it("should be able to close sio sending a srv", (done) => {
-      const PORT = 54018;
-      const srv = createServer().listen(PORT);
-      const sio = new Server(srv);
+      const httpServer = createServer().listen(0);
+      const io = new Server(httpServer);
+      const port = getPort(io);
       const net = require("net");
       const server = net.createServer();
 
-      const clientSocket = client(srv, { reconnection: false });
+      const clientSocket = client(httpServer, { reconnection: false });
 
       clientSocket.on("disconnect", () => {
-        expect(sio.sockets.sockets.size).to.equal(0);
-        server.listen(PORT);
+        expect(io.sockets.sockets.size).to.equal(0);
+        server.listen(port);
       });
 
       clientSocket.on("connect", () => {
-        expect(sio.sockets.sockets.size).to.equal(1);
-        sio.close();
+        expect(io.sockets.sockets.size).to.equal(1);
+        io.close();
       });
 
       server.once("listening", () => {
@@ -327,30 +333,31 @@ describe("socket.io", () => {
       });
     });
 
-    it("should be able to close sio sending a port", () => {
-      const PORT = 54019;
-      const sio = new Server(PORT);
+    it("should be able to close sio sending a srv", (done) => {
+      const io = new Server(0);
+      const port = getPort(io);
       const net = require("net");
       const server = net.createServer();
 
-      const clientSocket = ioc("ws://0.0.0.0:" + PORT, {
+      const clientSocket = ioc("ws://0.0.0.0:" + port, {
         reconnection: false,
       });
 
       clientSocket.on("disconnect", () => {
-        expect(Object.keys(sio._nsps["/"].sockets).length).to.equal(0);
-        server.listen(PORT);
+        expect(io.sockets.sockets.size).to.equal(0);
+        server.listen(port);
       });
 
       clientSocket.on("connect", () => {
-        expect(Object.keys(sio._nsps["/"].sockets).length).to.equal(1);
-        sio.close();
+        expect(io.sockets.sockets.size).to.equal(1);
+        io.close();
       });
 
       server.once("listening", () => {
         // PORT should be free
         server.close((error) => {
           expect(error).to.be(undefined);
+          done();
         });
       });
     });
@@ -802,6 +809,7 @@ describe("socket.io", () => {
       srv.listen(() => {
         const socket = client(srv);
 
+        // @ts-ignore
         socket.io.engine.write = () => {}; // prevent the client from sending a CONNECT packet
 
         socket.on("disconnect", () => {
@@ -812,7 +820,7 @@ describe("socket.io", () => {
       });
     });
 
-    it("should close a client without namespace", (done) => {
+    it("should close a client without namespace (2)", (done) => {
       const srv = createServer();
       const sio = new Server(srv, {
         connectTimeout: 100,
@@ -836,6 +844,27 @@ describe("socket.io", () => {
     });
 
     it("should exclude a specific socket when emitting", (done) => {
+      const srv = createServer();
+      const io = new Server(srv);
+
+      srv.listen(() => {
+        const socket1 = client(srv, "/");
+        const socket2 = client(srv, "/");
+
+        socket2.on("a", () => {
+          done(new Error("should not happen"));
+        });
+        socket1.on("a", () => {
+          done();
+        });
+
+        socket2.on("connect", () => {
+          io.except(socket2.id).emit("a");
+        });
+      });
+    });
+
+    it("should exclude a specific socket when emitting (in a namespace)", (done) => {
       const srv = createServer();
       const sio = new Server(srv);
 
@@ -886,6 +915,17 @@ describe("socket.io", () => {
       });
     });
 
+    it("should emit an 'new_namespace' event", (done) => {
+      const sio = new Server();
+
+      sio.on("new_namespace", (namespace) => {
+        expect(namespace.name).to.eql("/nsp");
+        done();
+      });
+
+      sio.of("/nsp");
+    });
+
     describe("dynamic namespaces", () => {
       it("should allow connections to dynamic namespaces with a regex", (done) => {
         const srv = createServer();
@@ -942,6 +982,64 @@ describe("socket.io", () => {
           });
         });
       });
+
+      it("should emit an 'new_namespace' event for a dynamic namespace", (done) => {
+        const srv = createServer();
+        const sio = new Server(srv);
+        srv.listen(() => {
+          sio.of(/^\/dynamic-\d+$/);
+
+          sio.on("new_namespace", (namespace) => {
+            expect(namespace.name).to.be("/dynamic-101");
+
+            socket.disconnect();
+            srv.close();
+            done();
+          });
+
+          const socket = client(srv, "/dynamic-101");
+        });
+      });
+
+      it("should handle race conditions with dynamic namespaces (#4136)", (done) => {
+        const srv = createServer();
+        const sio = new Server(srv);
+        const counters = {
+          connected: 0,
+          created: 0,
+          events: 0,
+        };
+        const buffer: callback[] = [];
+        sio.on("new_namespace", (namespace) => {
+          counters.created++;
+        });
+        srv.listen(() => {
+          const handler = () => {
+            if (++counters.events === 2) {
+              expect(counters.created).to.equal(1);
+              done();
+            }
+          };
+
+          sio
+            .of((name, query, next) => {
+              buffer.push(next);
+              if (buffer.length === 2) {
+                buffer.forEach((next) => next(null, true));
+              }
+            })
+            .on("connection", (socket) => {
+              if (++counters.connected === 2) {
+                sio.of("/dynamic-101").emit("message");
+              }
+            });
+
+          let one = client(srv, "/dynamic-101");
+          let two = client(srv, "/dynamic-101");
+          one.on("message", handler);
+          two.on("message", handler);
+        });
+      });
     });
   });
 
@@ -955,7 +1053,9 @@ describe("socket.io", () => {
           clientSocket.off("connect", init);
           clientSocket.io.engine.close();
 
-          clientSocket.connect();
+          process.nextTick(() => {
+            clientSocket.connect();
+          });
           clientSocket.on("connect", () => {
             done();
           });
@@ -1326,6 +1426,32 @@ describe("socket.io", () => {
       }, 200);
     });
 
+    it("should emit only one consecutive volatile event with binary (ws)", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv, { transports: ["websocket"] });
+
+      let counter = 0;
+      srv.listen(() => {
+        sio.on("connection", (s) => {
+          // Wait to make sure there are no packets being sent for opening the connection
+          setTimeout(() => {
+            s.volatile.emit("ev", Buffer.from([1, 2, 3]));
+            s.volatile.emit("ev", Buffer.from([4, 5, 6]));
+          }, 20);
+        });
+
+        const socket = client(srv, { transports: ["websocket"] });
+        socket.on("ev", () => {
+          counter++;
+        });
+      });
+
+      setTimeout(() => {
+        expect(counter).to.be(1);
+        done();
+      }, 200);
+    });
+
     it("should emit regular events after trying a failed volatile event (polling)", (done) => {
       const srv = createServer();
       const sio = new Server(srv, { transports: ["polling"] });
@@ -1750,6 +1876,7 @@ describe("socket.io", () => {
             console.log(
               "\u001b[96mNote: warning expected and normal in test.\u001b[39m"
             );
+            // @ts-ignore
             socket.io.engine.write("5woooot");
             setTimeout(() => {
               done();
@@ -1769,6 +1896,7 @@ describe("socket.io", () => {
             console.log(
               "\u001b[96mNote: warning expected and normal in test.\u001b[39m"
             );
+            // @ts-ignore
             socket.io.engine.write('44["handle me please"]');
             setTimeout(() => {
               done();
@@ -1789,6 +1917,7 @@ describe("socket.io", () => {
             done();
           });
           s.conn.on("upgrade", () => {
+            // @ts-ignore
             socket.io.engine.write("5woooot");
           });
         });
@@ -1806,6 +1935,7 @@ describe("socket.io", () => {
             done();
           });
           s.conn.on("upgrade", () => {
+            // @ts-ignore
             socket.io.engine.write("5");
           });
         });
@@ -2385,6 +2515,28 @@ describe("socket.io", () => {
         });
       });
     });
+
+    it("should pre encode a broadcast packet", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv);
+
+      srv.listen(() => {
+        const clientSocket = client(srv, { multiplex: false });
+
+        sio.on("connection", (socket) => {
+          socket.conn.on("packetCreate", (packet) => {
+            expect(packet.data).to.eql('2["hello","world"]');
+            expect(packet.options.wsPreEncoded).to.eql('42["hello","world"]');
+
+            clientSocket.close();
+            sio.close();
+            done();
+          });
+
+          sio.emit("hello", "world");
+        });
+      });
+    });
   });
 
   describe("middleware", () => {