Prevent socket timeouts by sending keepalive messages.

aduros · Nov 29, 2023 · 29ae46a · 29ae46a
1 parent f7f078f
commit 29ae46a
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Showing 2 changed files with 33 additions and 16 deletions.
diff --git a/runtimes/web/src/netplay/peer-manager.ts b/runtimes/web/src/netplay/peer-manager.ts
@@ -1,5 +1,5 @@
 /** WebRTC signaling messages. */
-type Message = WhoAmIRequestMessage | WhoAmIReplyMessage | OfferMessage | AnswerMessage | CandidateMessage | AbortMessage;
+type Message = WhoAmIRequestMessage | WhoAmIReplyMessage | OfferMessage | AnswerMessage | CandidateMessage | AbortMessage | KeepaliveMessage;
 
 /** Sent by a newly connecting client requesting its peer ID. */
 type WhoAmIRequestMessage = {
@@ -31,16 +31,26 @@ type AbortMessage = {
     type: "ABORT";
 }
 
+type KeepaliveMessage = {
+    type: "KEEPALIVE";
+}
+
 /**
  * Connects to our websocket server for exchanging the signaling messages needed to establish WebRTC
  * peer-to-peer connections.
  */
 class SignalClient {
     private socket?: WebSocket;
     private readonly bufferedOutput: string[] = [];
+    private keepaliveInterval: number;
 
     constructor (private onMessage: (source: string, message: Message) => void) {
         this.connect();
+
+        // Regularly send messages to keep the websocket connection from an idle timeout
+        this.keepaliveInterval = window.setInterval(() => {
+            this.send("", { type: "KEEPALIVE" }, false);
+        }, 15000);
     }
 
     private async connect (): Promise<void> {
@@ -81,18 +91,19 @@ class SignalClient {
         this.bufferedOutput.length = 0;
     }
 
-    send (target: string, message: Message) {
+    send (target: string, message: Message, deferIfNotReady = true) {
         // console.log(`Sent ${message.type} message to ${target}`);
         const output = JSON.stringify({ target, message });
         if (this.socket?.readyState == 1) {
             this.socket.send(output);
-        } else {
+        } else if (deferIfNotReady) {
             this.bufferedOutput.push(output);
         }
     }
 
     close () {
         this.socket?.close();
+        window.clearInterval(this.keepaliveInterval);
     }
 }
 

diff --git a/runtimes/web/webrtc-signal-server/src/main.ts b/runtimes/web/webrtc-signal-server/src/main.ts
@@ -23,20 +23,26 @@ export const handler: APIGatewayProxyWebsocketHandlerV2 = async ({ body, request
   if (body) {
     const { target, message } = JSON.parse(body);
 
-    if (message.type === "WHOAMI_REQUEST") {
-      await sendToPeer("server", requestContext.connectionId, {
-        type: "WHOAMI_REPLY",
-        yourPeerId: requestContext.connectionId,
-      });
-    } else {
-      try {
-        await sendToPeer(requestContext.connectionId, target, message);
-      } catch (error) {
-        // Peer not found, send an abort message
-        await sendToPeer(target, requestContext.connectionId, {
-          type: "ABORT",
+    switch (message.type) {
+      case "WHOAMI_REQUEST":
+        await sendToPeer("server", requestContext.connectionId, {
+          type: "WHOAMI_REPLY",
+          yourPeerId: requestContext.connectionId,
         });
-      }
+        break;
+      case "KEEPALIVE":
+        // Ignore this message, it only exists to keep the connection open
+        break;
+      default:
+        // Route the message to the given target
+        try {
+          await sendToPeer(requestContext.connectionId, target, message);
+        } catch (error) {
+          // Peer not found, send an abort message
+          await sendToPeer(target, requestContext.connectionId, {
+            type: "ABORT",
+          });
+        }
     }
   }