htlcswitch: pass quit chans as unidirectional

This is a requirement for replacing the quit channel with a Context.
The Done() channel of a Context is always recv-only, so all users of
that channel must not expect a bidirectional channel.

htlcswitch/link_test.go

@@ -2197,17 +2197,21 @@ func newSingleLinkTestHarness(t *testing.T, chanAmt,
 		return nil
 	}
 
+	forwardPackets := func(linkQuit <-chan struct{}, _ bool,
+		packets ...*htlcPacket) error {
+
+		return aliceSwitch.ForwardPackets(linkQuit, packets...)
+	}
+
 	// Instantiate with a long interval, so that we can precisely control
 	// the firing via force feeding.
 	bticker := ticker.NewForce(time.Hour)
 	aliceCfg := ChannelLinkConfig{
-		FwrdingPolicy: globalPolicy,
-		Peer:          alicePeer,
-		BestHeight:    aliceSwitch.BestHeight,
-		Circuits:      aliceSwitch.CircuitModifier(),
-		ForwardPackets: func(linkQuit chan struct{}, _ bool, packets ...*htlcPacket) error {
-			return aliceSwitch.ForwardPackets(linkQuit, packets...)
-		},
+		FwrdingPolicy:      globalPolicy,
+		Peer:               alicePeer,
+		BestHeight:         aliceSwitch.BestHeight,
+		Circuits:           aliceSwitch.CircuitModifier(),
+		ForwardPackets:     forwardPackets,
 		DecodeHopIterators: decoder.DecodeHopIterators,
 		ExtractErrorEncrypter: func(*btcec.PublicKey) (
 			hop.ErrorEncrypter, lnwire.FailCode) {
@@ -4867,17 +4871,21 @@ func (h *persistentLinkHarness) restartLink(
 		return nil
 	}
 
+	forwardPackets := func(linkQuit <-chan struct{}, _ bool,
+		packets ...*htlcPacket) error {
+
+		return h.hSwitch.ForwardPackets(linkQuit, packets...)
+	}
+
 	// Instantiate with a long interval, so that we can precisely control
 	// the firing via force feeding.
 	bticker := ticker.NewForce(time.Hour)
 	aliceCfg := ChannelLinkConfig{
-		FwrdingPolicy: globalPolicy,
-		Peer:          alicePeer,
-		BestHeight:    h.hSwitch.BestHeight,
-		Circuits:      h.hSwitch.CircuitModifier(),
-		ForwardPackets: func(linkQuit chan struct{}, _ bool, packets ...*htlcPacket) error {
-			return h.hSwitch.ForwardPackets(linkQuit, packets...)
-		},
+		FwrdingPolicy:      globalPolicy,
+		Peer:               alicePeer,
+		BestHeight:         h.hSwitch.BestHeight,
+		Circuits:           h.hSwitch.CircuitModifier(),
+		ForwardPackets:     forwardPackets,
 		DecodeHopIterators: decoder.DecodeHopIterators,
 		ExtractErrorEncrypter: func(*btcec.PublicKey) (
 			hop.ErrorEncrypter, lnwire.FailCode) {
@@ -7037,7 +7045,7 @@ func TestPipelineSettle(t *testing.T) {
 	// erroneously forwarded. If the forwardChan is closed before the last
 	// step, then the test will fail.
 	forwardChan := make(chan struct{})
-	fwdPkts := func(c chan struct{}, _ bool, hp ...*htlcPacket) error {
+	fwdPkts := func(c <-chan struct{}, _ bool, hp ...*htlcPacket) error {
 		close(forwardChan)
 		return nil
 	}
@@ -7223,7 +7231,7 @@ func TestChannelLinkShortFailureRelay(t *testing.T) {
 	aliceMsgs := mockPeer.sentMsgs
 	switchChan := make(chan *htlcPacket)
 
-	coreLink.cfg.ForwardPackets = func(linkQuit chan struct{}, _ bool,
+	coreLink.cfg.ForwardPackets = func(linkQuit <-chan struct{}, _ bool,
 		packets ...*htlcPacket) error {
 
 		for _, p := range packets {