Rate limit web socket messages, close connection if limit exceeded

The host will reconnect afterward, so future legitimate uses shouldn't
be compromised, but the misbehaving action or loop should be terminated
by the thrown error which should alert the users to look into their
code.

src/classes/ISocket.ts

@@ -11,6 +11,8 @@ const MESSAGE_META = z.object({
 
 export class TimeoutError extends Error {}
 
+export class NotConnectedError extends Error {}
+
 interface PendingMessage {
   data: string
   onAckReceived: () => void
@@ -46,6 +48,7 @@ export default class ISocket {
   private pingTimeout: number
   private isAuthenticated: boolean
   private timeouts: Set<NodeJS.Timeout>
+  private isClosed = false
   onMessage: Evt<string>
   onOpen: Evt<void>
   onError: Evt<Error>
@@ -95,6 +98,8 @@ export default class ISocket {
    * throwing an error if `ACK` is not received within `sendTimeout`.
    */
   async send(data: string) {
+    if (this.isClosed) throw new NotConnectedError()
+
     return new Promise<void>((resolve, reject) => {
       const id = v4()
 
@@ -121,8 +126,10 @@ export default class ISocket {
    * Close the underlying WebSocket connection, and this ISocket
    * connection.
    */
-  close() {
-    return this.ws.close()
+  close(code?: number, reason?: string) {
+    this.isClosed = true
+    this.onMessage.detach()
+    return this.ws.close(code, reason)
   }
 
   constructor(ws: WebSocket | NodeWebSocket, config?: ISocketConfig) {
@@ -148,13 +155,15 @@ export default class ISocket {
     this.isAuthenticated = false
 
     this.onClose.attach(() => {
+      this.isClosed = true
       for (const timeout of this.timeouts) {
         clearTimeout(timeout)
       }
       this.timeouts.clear()
     })
 
     this.ws.onopen = () => {
+      this.isClosed = false
       this.onOpen.post()
     }
 
@@ -172,6 +181,9 @@ export default class ISocket {
       if (evt.stopPropagation) {
         evt.stopPropagation()
       }
+
+      if (this.isClosed) return
+
       const data = JSON.parse(evt.data.toString())
       const meta = MESSAGE_META.parse(data)
 
@@ -218,6 +230,8 @@ export default class ISocket {
    * `pong` is not received within `pingTimeout`.
    */
   async ping() {
+    if (this.isClosed) throw new NotConnectedError()
+
     if (!('ping' in this.ws)) {
       // Not supported in web client WebSocket
       throw new Error(

src/examples/basic/index.ts

@@ -689,7 +689,7 @@ const interval = new Interval({
       }
     },
     log_dos: async () => {
-      for (let i = 0; i < 100_000; i++) {
+      for (let i = 0; i < 1000; i++) {
         await ctx.log(i)
       }
     },