Ping the websocket every 30 second disconencts are noticed. (#56)

Sometimes socket are not closed neatly and the connection to a
(in-between) load balancer can be kept open. This pinging should trigger
the TCP protocol to disconnect.

internal/signaling/handler.go

@@ -71,6 +71,21 @@ func Handler(ctx context.Context, store stores.Store, cloudflare *cloudflare.Cre
 			}
 		}()
 
+		go func() { // Sending ping packet every 30 to check if the tcp connection is still alive.
+			ticker := time.NewTicker(30 * time.Second)
+			defer ticker.Stop()
+			for {
+				select {
+				case <-ticker.C:
+					if err := peer.Send(ctx, PingPacket{Type: "ping"}); err != nil {
+						util.ErrorAndDisconnect(ctx, conn, err)
+					}
+				case <-ctx.Done():
+					return
+				}
+			}
+		}()
+
 		for ctx.Err() == nil {
 			var raw []byte
 			if _, raw, err = conn.Read(ctx); err != nil {
@@ -109,6 +124,9 @@ func Handler(ctx context.Context, store stores.Store, cloudflare *cloudflare.Cre
 				}
 				go metrics.RecordEvent(ctx, params)
 
+			case "pong":
+				// ignore, ping/pong is just for the tcp keepalive.
+
 			default:
 				if err := peer.HandlePacket(ctx, typeOnly.Type, raw); err != nil {
 					util.ErrorAndDisconnect(ctx, conn, err)

internal/signaling/types.go

@@ -8,6 +8,10 @@ import (
 	"github.com/poki/netlib/internal/signaling/stores"
 )
 
+type PingPacket struct {
+	Type string `json:"type"`
+}
+
 type HelloPacket struct {
 	Type string `json:"type"`
 

lib/signaling.ts

@@ -209,6 +209,8 @@ export default class Signaling extends EventEmitter<SignalingListeners> {
         case 'credentials':
           this.emit('credentials', packet)
           break
+        case 'ping':
+          break
       }
     } catch (e) {
       const error = new SignalingError('unknown-error', e as string)

lib/types.ts

@@ -42,8 +42,13 @@ export type SignalingPacketTypes =
 | JoinPacket
 | ListPacket
 | LobbiesPacket
+| PingPacket
 | WelcomePacket
 
+export interface PingPacket extends Base {
+  type: 'ping'
+}
+
 export interface ErrorPacket extends Base {
   type: 'error'
   message: string