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

jpillora#488

share/tunnel/tunnel.go

@@ -166,18 +166,44 @@ func (t *Tunnel) BindRemotes(ctx context.Context, remotes []*settings.Remote) er
 }
 
 func (t *Tunnel) keepAliveLoop(sshConn ssh.Conn) {
-	//ping forever
+	// ping forever with a timeout
+PingCheckOLoop:
 	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
+
+		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 ssh connection on abnormal ping
+	// Close the SSH connection on abnormal ping
 	sshConn.Close()
 }