Modify keepAliveLoop to async for enabling timeout on no-response ping

share/tunnel/tunnel.go

@@ -173,18 +173,44 @@ func (t *Tunnel) BindRemotes(ctx context.Context, remotes []*settings.Remote) er
 }
 
 func (t *Tunnel) keepAliveLoop(sshConn ssh.Conn) {
-	//ping forever
-	for {
-		time.Sleep(t.Config.KeepAlive)
-		_, b, err := sshConn.SendRequest("ping", true, nil)
-		if err != nil {
-			break
-		}
-		if len(b) > 0 && !bytes.Equal(b, []byte("pong")) {
-			t.Debugf("strange ping response")
-			break
-		}
-	}
-	//close ssh connection on abnormal ping
-	sshConn.Close()
+        // ping forever with a timeout
+        PingCheckOLoop:
+        for {
+                time.Sleep(t.Config.KeepAlive)
+
+                ctx, cancel := context.WithTimeout(context.Background(), t.Config.KeepAlive)
+                defer cancel()
+
+                responseCh := make(chan []byte, 1)
+                errCh := make(chan error, 1)
+
+                // Asynchronously send a 'ping' request via SSH
+                go func() {
+                        _, b, err := sshConn.SendRequest("ping", true, nil)
+                        if err != nil {
+                                errCh <- err
+                                return
+                        }
+                        responseCh <- b
+                }()
+
+                // Wait for a response, error, or timeout from the asynchronous 'ping' request
+                select {
+                case response := <-responseCh:
+                        if len(response) > 0 && !bytes.Equal(response, []byte("pong")) {
+                                t.Debugf("Unexpected ping response: %s", response)
+                                break PingCheckOLoop
+                        }
+                case err := <-errCh:
+                        if err != nil {
+                                t.Debugf("Failed to send ping: %s", err)
+                                break PingCheckOLoop
+                        }
+                case <-ctx.Done():
+                        t.Debugf("Ping timed out")
+                        break PingCheckOLoop
+                }
+        }
+        // Close the SSH connection on abnormal ping
+        sshConn.Close()
 }