TUN-7480: Added a timeout for unregisterUDP.

I deliberately kept this as an unregistertimeout because that was the
intent. In the future we could change this to a UDPConnConfig if we want
to pass multiple values here.

The idea of this PR is simply to add a configurable unregister UDP
timeout.

cmd/cloudflared/tunnel/cmd.go

@@ -79,6 +79,9 @@ const (
 	// hostKeyPath is the path of the dir to save SSH host keys too
 	hostKeyPath = "host-key-path"
 
+	// udpUnregisterSessionTimeout is how long we wait before we stop trying to unregister a UDP session from the edge
+	udpUnregisterSessionTimeoutFlag = "udp-unregister-session-timeout"
+
 	// uiFlag is to enable launching cloudflared in interactive UI mode
 	uiFlag = "ui"
 
@@ -683,6 +686,11 @@ func tunnelFlags(shouldHide bool) []cli.Flag {
 			Value:  4,
 			Hidden: true,
 		}),
+		altsrc.NewDurationFlag(&cli.DurationFlag{
+			Name:   udpUnregisterSessionTimeoutFlag,
+			Value:  5 * time.Second,
+			Hidden: true,
+		}),
 		altsrc.NewStringFlag(&cli.StringFlag{
 			Name:  connectorLabelFlag,
 			Usage: "Use this option to give a meaningful label to a specific connector. When a tunnel starts up, a connector id unique to the tunnel is generated. This is a uuid. To make it easier to identify a connector, we will use the hostname of the machine the tunnel is running on along with the connector ID. This option exists if one wants to have more control over what their individual connectors are called.",

cmd/cloudflared/tunnel/configuration.go

@@ -239,6 +239,7 @@ func prepareTunnelConfig(
 		NeedPQ:                      needPQ,
 		PQKexIdx:                    pqKexIdx,
 		MaxEdgeAddrRetries:          uint8(c.Int("max-edge-addr-retries")),
+		UDPUnregisterSessionTimeout: c.Duration(udpUnregisterSessionTimeoutFlag),
 	}
 	packetConfig, err := newPacketConfig(c, log)
 	if err != nil {

connection/quic.go

@@ -63,6 +63,8 @@ type QUICConnection struct {
 	controlStreamHandler ControlStreamHandler
 	connOptions          *tunnelpogs.ConnectionOptions
 	connIndex            uint8
+
+	udpUnregisterTimeout time.Duration
 }
 
 // NewQUICConnection returns a new instance of QUICConnection.
@@ -78,6 +80,7 @@ func NewQUICConnection(
 	controlStreamHandler ControlStreamHandler,
 	logger *zerolog.Logger,
 	packetRouterConfig *ingress.GlobalRouterConfig,
+	udpUnregisterTimeout time.Duration,
 ) (*QUICConnection, error) {
 	udpConn, err := createUDPConnForConnIndex(connIndex, localAddr, logger)
 	if err != nil {
@@ -112,6 +115,7 @@ func NewQUICConnection(
 		controlStreamHandler: controlStreamHandler,
 		connOptions:          connOptions,
 		connIndex:            connIndex,
+		udpUnregisterTimeout: udpUnregisterTimeout,
 	}, nil
 }
 
@@ -370,7 +374,7 @@ func (q *QUICConnection) closeUDPSession(ctx context.Context, sessionID uuid.UUI
 
 	stream := quicpogs.NewSafeStreamCloser(quicStream)
 	defer stream.Close()
-	rpcClientStream, err := quicpogs.NewRPCClientStream(ctx, stream, q.logger)
+	rpcClientStream, err := quicpogs.NewRPCClientStream(ctx, stream, q.udpUnregisterTimeout, q.logger)
 	if err != nil {
 		// Log this at debug because this is not an error if session was closed due to lost connection
 		// with edge

connection/quic_test.go

@@ -725,6 +725,7 @@ func testQUICConnection(udpListenerAddr net.Addr, t *testing.T, index uint8) *QU
 		fakeControlStream{},
 		&log,
 		nil,
+		5*time.Second,
 	)
 	require.NoError(t, err)
 	return qc

quic/quic_protocol.go

@@ -229,9 +229,12 @@ func writeSignature(stream io.Writer, signature ProtocolSignature) error {
 type RPCClientStream struct {
 	client    tunnelpogs.CloudflaredServer_PogsClient
 	transport rpc.Transport
+
+	// Time we wait for the server to respond to a request before we close the connection.
+	rpcUnregisterUDPSessionDeadline time.Duration
 }
 
-func NewRPCClientStream(ctx context.Context, stream io.ReadWriteCloser, logger *zerolog.Logger) (*RPCClientStream, error) {
+func NewRPCClientStream(ctx context.Context, stream io.ReadWriteCloser, rpcUnregisterUDPSessionDeadline time.Duration, logger *zerolog.Logger) (*RPCClientStream, error) {
 	n, err := stream.Write(RPCStreamProtocolSignature[:])
 	if err != nil {
 		return nil, err
@@ -247,6 +250,7 @@ func NewRPCClientStream(ctx context.Context, stream io.ReadWriteCloser, logger *
 	return &RPCClientStream{
 		client:                          tunnelpogs.NewCloudflaredServer_PogsClient(conn.Bootstrap(ctx), conn),
 		transport:                       transport,
+		rpcUnregisterUDPSessionDeadline: rpcUnregisterUDPSessionDeadline,
 	}, nil
 }
 
@@ -255,6 +259,8 @@ func (rcs *RPCClientStream) RegisterUdpSession(ctx context.Context, sessionID uu
 }
 
 func (rcs *RPCClientStream) UnregisterUdpSession(ctx context.Context, sessionID uuid.UUID, message string) error {
+	ctx, cancel := context.WithTimeout(ctx, rcs.rpcUnregisterUDPSessionDeadline)
+	defer cancel()
 	return rcs.client.UnregisterUdpSession(ctx, sessionID, message)
 }
 

quic/quic_protocol_test.go

@@ -109,6 +109,63 @@ func TestConnectResponseMeta(t *testing.T) {
 	}
 }
 
+func TestUnregisterUdpSession(t *testing.T) {
+	unregisterMessage := "closed by eyeball"
+
+	var tests = []struct {
+		name             string
+		sessionRPCServer mockSessionRPCServer
+		timeout          time.Duration
+	}{
+
+		{
+			name: "UnregisterUdpSessionTimesout if the RPC server does not respond",
+			sessionRPCServer: mockSessionRPCServer{
+				sessionID:         uuid.New(),
+				dstIP:             net.IP{172, 16, 0, 1},
+				dstPort:           8000,
+				closeIdleAfter:    testCloseIdleAfterHint,
+				unregisterMessage: unregisterMessage,
+				traceContext:      "1241ce3ecdefc68854e8514e69ba42ca:b38f1bf5eae406f3:0:1",
+			},
+			// very very low value so we trigger the timeout every time.
+			timeout: time.Nanosecond * 1,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			logger := zerolog.Nop()
+			clientStream, serverStream := newMockRPCStreams()
+			sessionRegisteredChan := make(chan struct{})
+			go func() {
+				protocol, err := DetermineProtocol(serverStream)
+				assert.NoError(t, err)
+				rpcServerStream, err := NewRPCServerStream(serverStream, protocol)
+				assert.NoError(t, err)
+				err = rpcServerStream.Serve(test.sessionRPCServer, nil, &logger)
+				assert.NoError(t, err)
+
+				serverStream.Close()
+				close(sessionRegisteredChan)
+			}()
+
+			rpcClientStream, err := NewRPCClientStream(context.Background(), clientStream, test.timeout, &logger)
+			assert.NoError(t, err)
+
+			reg, err := rpcClientStream.RegisterUdpSession(context.Background(), test.sessionRPCServer.sessionID, test.sessionRPCServer.dstIP, test.sessionRPCServer.dstPort, testCloseIdleAfterHint, test.sessionRPCServer.traceContext)
+			assert.NoError(t, err)
+			assert.NoError(t, reg.Err)
+
+			assert.Error(t, rpcClientStream.UnregisterUdpSession(context.Background(), test.sessionRPCServer.sessionID, unregisterMessage))
+
+			rpcClientStream.Close()
+			<-sessionRegisteredChan
+		})
+	}
+
+}
+
 func TestRegisterUdpSession(t *testing.T) {
 	unregisterMessage := "closed by eyeball"
 
@@ -157,7 +214,7 @@ func TestRegisterUdpSession(t *testing.T) {
 				close(sessionRegisteredChan)
 			}()
 
-			rpcClientStream, err := NewRPCClientStream(context.Background(), clientStream, &logger)
+			rpcClientStream, err := NewRPCClientStream(context.Background(), clientStream, 5*time.Second, &logger)
 			assert.NoError(t, err)
 
 			reg, err := rpcClientStream.RegisterUdpSession(context.Background(), test.sessionRPCServer.sessionID, test.sessionRPCServer.dstIP, test.sessionRPCServer.dstPort, testCloseIdleAfterHint, test.sessionRPCServer.traceContext)
@@ -208,7 +265,7 @@ func TestManageConfiguration(t *testing.T) {
 
 	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
 	defer cancel()
-	rpcClientStream, err := NewRPCClientStream(ctx, clientStream, &logger)
+	rpcClientStream, err := NewRPCClientStream(ctx, clientStream, 5*time.Second, &logger)
 	assert.NoError(t, err)
 
 	result, err := rpcClientStream.UpdateConfiguration(ctx, version, config)

supervisor/tunnel.go

@@ -68,6 +68,8 @@ type TunnelConfig struct {
 	ProtocolSelector connection.ProtocolSelector
 	EdgeTLSConfigs   map[connection.Protocol]*tls.Config
 	PacketConfig     *ingress.GlobalRouterConfig
+
+	UDPUnregisterSessionTimeout time.Duration
 }
 
 func (c *TunnelConfig) registrationOptions(connectionID uint8, OriginLocalIP string, uuid uuid.UUID) *tunnelpogs.RegistrationOptions {
@@ -615,7 +617,9 @@ func (e *EdgeTunnelServer) serveQUIC(
 		connOptions,
 		controlStreamHandler,
 		connLogger.Logger(),
-		e.config.PacketConfig)
+		e.config.PacketConfig,
+		e.config.UDPUnregisterSessionTimeout,
+	)
 	if err != nil {
 		if e.config.NeedPQ {
 			handlePQTunnelError(err, e.config)