htlcswitch+peer: pass BestHeight to ChannelLinkConfig

This allows non-test usages of ChannelLinkConfig to omit the raw
htlcswitch.Switch pointer.

htlcswitch/link.go

@@ -134,6 +134,9 @@ type ChannelLinkConfig struct {
 	// TODO(conner): remove after refactoring htlcswitch testing framework.
 	Switch *Switch
 
+	// BestHeight returns the best known height.
+	BestHeight func() uint32
+
 	// ForwardPackets attempts to forward the batch of htlcs through the
 	// switch. The function returns and error in case it fails to send one or
 	// more packets. The link's quit signal should be provided to allow
@@ -2677,7 +2680,7 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 			continue
 		}
 
-		heightNow := l.cfg.Switch.BestHeight()
+		heightNow := l.cfg.BestHeight()
 
 		pld, err := chanIterator.HopPayload()
 		if err != nil {

htlcswitch/link_test.go

@@ -1951,6 +1951,7 @@ func newSingleLinkTestHarness(chanAmt, chanReserve btcutil.Amount) (
 		FwrdingPolicy:      globalPolicy,
 		Peer:               alicePeer,
 		Switch:             aliceSwitch,
+		BestHeight:         aliceSwitch.BestHeight,
 		Circuits:           aliceSwitch.CircuitModifier(),
 		ForwardPackets:     aliceSwitch.ForwardPackets,
 		DecodeHopIterators: decoder.DecodeHopIterators,
@@ -4454,6 +4455,7 @@ func (h *persistentLinkHarness) restartLink(
 		FwrdingPolicy:      globalPolicy,
 		Peer:               alicePeer,
 		Switch:             aliceSwitch,
+		BestHeight:         aliceSwitch.BestHeight,
 		Circuits:           aliceSwitch.CircuitModifier(),
 		ForwardPackets:     aliceSwitch.ForwardPackets,
 		DecodeHopIterators: decoder.DecodeHopIterators,

htlcswitch/test_utils.go

@@ -1119,6 +1119,7 @@ func (h *hopNetwork) createChannelLink(server, peer *mockServer,
 	link := NewChannelLink(
 		ChannelLinkConfig{
 			Switch:             server.htlcSwitch,
+			BestHeight:         server.htlcSwitch.BestHeight,
 			FwrdingPolicy:      h.globalPolicy,
 			Peer:               peer,
 			Circuits:           server.htlcSwitch.CircuitModifier(),

peer/brontide.go

@@ -813,7 +813,7 @@ func (p *Brontide) addLink(chanPoint *wire.OutPoint,
 		FetchLastChannelUpdate:  p.cfg.FetchLastChanUpdate,
 		HodlMask:                p.cfg.Hodl.Mask(),
 		Registry:                p.cfg.Invoices,
-		Switch:                  p.cfg.Switch,
+		BestHeight:              p.cfg.Switch.BestHeight,
 		Circuits:                p.cfg.Switch.CircuitModifier(),
 		ForwardPackets:          p.cfg.InterceptSwitch.ForwardPackets,
 		FwrdingPolicy:           *forwardingPolicy,