add keepalive message to prevent proxies closing the connection

protocol/src/protocol.ts

@@ -2,6 +2,7 @@ export * from './admin.js';
 
 export enum MSAgentProtocolMessageType {
     // Client-to-server
+    KeepAlive = "nop",
     Join = "join",
     Talk = "talk",
     Admin = "admin",

server/src/client.ts

@@ -25,6 +25,9 @@ export class Client extends EventEmitter {
     room: MSAgentChatRoom;
     socket: WebSocket;
 
+    nopTimer: NodeJS.Timeout | undefined;
+    nopLevel: number;
+
     chatRateLimit: RateLimiter
 
     constructor(socket: WebSocket, room: MSAgentChatRoom, ip: string) {
@@ -35,6 +38,8 @@ export class Client extends EventEmitter {
         this.username = null;
         this.agent = null;
         this.admin = false;
+        this.resetNop();
+        this.nopLevel = 0;
         
         this.chatRateLimit = new RateLimiter(this.room.config.ratelimits.chat);
 
@@ -67,6 +72,20 @@ export class Client extends EventEmitter {
         });
     }
 
+    private resetNop() {
+        clearInterval(this.nopTimer);
+        this.nopLevel = 0;
+        this.nopTimer = setInterval(() => {
+            if (this.nopLevel++ >= 3) {
+                this.socket.close();
+            } else {
+                this.send({
+                    op: MSAgentProtocolMessageType.KeepAlive
+                });
+            }
+        }, 10000)
+    }
+
     private async parseMessage(data: string) {
         let msg: MSAgentProtocolMessage;
         try {
@@ -75,6 +94,7 @@ export class Client extends EventEmitter {
             this.socket.close();
             return;
         }
+        this.resetNop();
         switch (msg.op) {
             case MSAgentProtocolMessageType.Join: {
                 let joinMsg = msg as MSAgentJoinMessage;

webapp/src/ts/client.ts

@@ -249,6 +249,12 @@ export class MSAgentClient {
 			return;
 		}
 		switch (msg.op) {
+			case MSAgentProtocolMessageType.KeepAlive: {
+				this.send({
+					op: MSAgentProtocolMessageType.KeepAlive
+				});
+				break;
+			}
 			case MSAgentProtocolMessageType.Init: {
 				let initMsg = msg as MSAgentInitMessage;
 				this.username = initMsg.data.username;