htlcswitch+routing: add htlc blob to ShouldHandleTraffic

Whether we should let the aux bandwidth manager decide what the
bandwidth of a channel is should also depend on whether the HTLC is a
custom HTLC, not just the channel.

htlcswitch/interfaces.go

@@ -509,7 +509,7 @@ type AuxTrafficShaper interface {
 	// identified by the provided channel ID may have external mechanisms
 	// that would allow it to carry out the payment.
 	ShouldHandleTraffic(cid lnwire.ShortChannelID,
-		fundingBlob fn.Option[tlv.Blob]) (bool, error)
+		fundingBlob, htlcBlob fn.Option[tlv.Blob]) (bool, error)
 
 	// PaymentBandwidth returns the available bandwidth for a custom channel
 	// decided by the given channel aux blob and HTLC blob. A return value

htlcswitch/link.go

@@ -3484,7 +3484,7 @@ func (l *channelLink) AuxBandwidth(amount lnwire.MilliSatoshi,
 	ts AuxTrafficShaper) fn.Result[OptionalBandwidth] {
 
 	fundingBlob := l.FundingCustomBlob()
-	shouldHandle, err := ts.ShouldHandleTraffic(cid, fundingBlob)
+	shouldHandle, err := ts.ShouldHandleTraffic(cid, fundingBlob, htlcBlob)
 	if err != nil {
 		return fn.Err[OptionalBandwidth](fmt.Errorf("traffic shaper "+
 			"failed to decide whether to handle traffic: %w", err))

routing/bandwidth_test.go

@@ -140,7 +140,7 @@ type mockTrafficShaper struct{}
 // by the provided channel ID may have external mechanisms that would
 // allow it to carry out the payment.
 func (*mockTrafficShaper) ShouldHandleTraffic(_ lnwire.ShortChannelID,
-	_ fn.Option[tlv.Blob]) (bool, error) {
+	_, _ fn.Option[tlv.Blob]) (bool, error) {
 
 	return true, nil
 }