htlcswitch: add InterceptableSwitchConfig

Preparation for adding more config options.

htlcswitch/interceptable_switch.go

@@ -111,19 +111,32 @@ type fwdResolution struct {
 	errChan    chan error
 }
 
-// NewInterceptableSwitch returns an instance of InterceptableSwitch.
+// InterceptableSwitchConfig contains the configuration of InterceptableSwitch.
-func NewInterceptableSwitch(s *Switch, cltvRejectDelta uint32,
+type InterceptableSwitchConfig struct {
-	requireInterceptor bool) *InterceptableSwitch {
+	// Switch is a reference to the actual switch implementation that
+	// packets get sent to on resume.
+	Switch *Switch
 
+	// CltvRejectDelta defines the number of blocks before the expiry of the
+	// htlc where we no longer intercept it and instead cancel it back.
+	CltvRejectDelta uint32
+
+	// RequireInterceptor indicates whether processing should block if no
+	// interceptor is connected.
+	RequireInterceptor bool
+}
+
+// NewInterceptableSwitch returns an instance of InterceptableSwitch.
+func NewInterceptableSwitch(cfg *InterceptableSwitchConfig) *InterceptableSwitch {
 	return &InterceptableSwitch{
-		htlcSwitch:              s,
+		htlcSwitch:              cfg.Switch,
 		intercepted:             make(chan *interceptedPackets),
 		onchainIntercepted:      make(chan InterceptedForward),
 		interceptorRegistration: make(chan ForwardInterceptor),
 		holdForwards:            make(map[channeldb.CircuitKey]InterceptedForward),
 		resolutionChan:          make(chan *fwdResolution),
-		requireInterceptor:      requireInterceptor,
+		requireInterceptor:      cfg.RequireInterceptor,
-		cltvRejectDelta:         cltvRejectDelta,
+		cltvRejectDelta:         cfg.CltvRejectDelta,
 
 		quit: make(chan struct{}),
 	}

htlcswitch/switch_test.go

@@ -3846,7 +3846,10 @@ func TestSwitchHoldForward(t *testing.T) {
 		interceptedChan: make(chan InterceptedPacket),
 	}
 	switchForwardInterceptor := NewInterceptableSwitch(
-		s, cltvRejectDelta, false,
+		&InterceptableSwitchConfig{
+			Switch:          s,
+			CltvRejectDelta: cltvRejectDelta,
+		},
 	)
 	require.NoError(t, switchForwardInterceptor.Start())
 
@@ -4037,7 +4040,13 @@ func TestSwitchHoldForward(t *testing.T) {
 	require.NoError(t, switchForwardInterceptor.Stop())
 
 	// Test always-on interception.
-	switchForwardInterceptor = NewInterceptableSwitch(s, cltvRejectDelta, true)
+	switchForwardInterceptor = NewInterceptableSwitch(
+		&InterceptableSwitchConfig{
+			Switch:             s,
+			CltvRejectDelta:    cltvRejectDelta,
+			RequireInterceptor: true,
+		},
+	)
 	require.NoError(t, switchForwardInterceptor.Start())
 
 	// Forward a fresh packet. It is expected to be failed immediately,
@@ -5329,7 +5338,11 @@ func testSwitchAliasInterceptFail(t *testing.T, zeroConf bool) {
 		t:               t,
 		interceptedChan: make(chan InterceptedPacket),
 	}
-	interceptSwitch := NewInterceptableSwitch(s, 0, false)
+	interceptSwitch := NewInterceptableSwitch(
+		&InterceptableSwitchConfig{
+			Switch: s,
+		},
+	)
 	require.NoError(t, interceptSwitch.Start())
 	interceptSwitch.SetInterceptor(forwardInterceptor.InterceptForwardHtlc)
 

peer/test_utils.go

@@ -367,7 +367,9 @@ func createTestPeer(t *testing.T, notifier chainntnfs.ChainNotifier,
 		Switch:            mockSwitch,
 		ChanActiveTimeout: chanActiveTimeout,
 		InterceptSwitch: htlcswitch.NewInterceptableSwitch(
-			nil, testCltvRejectDelta, false,
+			&htlcswitch.InterceptableSwitchConfig{
+				CltvRejectDelta: testCltvRejectDelta,
+			},
 		),
 		ChannelDB:      dbAlice.ChannelStateDB(),
 		FeeEstimator:   estimator,

server.go

@@ -667,8 +667,11 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		return nil, err
 	}
 	s.interceptableSwitch = htlcswitch.NewInterceptableSwitch(
-		s.htlcSwitch, lncfg.DefaultFinalCltvRejectDelta,
+		&htlcswitch.InterceptableSwitchConfig{
-		s.cfg.RequireInterceptor,
+			Switch:             s.htlcSwitch,
+			CltvRejectDelta:    lncfg.DefaultFinalCltvRejectDelta,
+			RequireInterceptor: s.cfg.RequireInterceptor,
+		},
 	)
 
 	s.witnessBeacon = newPreimageBeacon(