Only Update Inbound Fee if specified.

cmd/lncli/commands.go

@@ -2395,6 +2395,12 @@ func updateChannelPolicy(ctx *cli.Context) error {
 		InboundFeeRatePpm:  int32(inboundFeeRatePpm),
 	}
 
+	// Only apply the inbound fees if they are specified.
+	if ctx.IsSet("inbound_base_fee_msat") ||
+		ctx.IsSet("inbound_fee_rate_ppm") {
+		req.InboundFeeSpecified = true
+	}
+
 	if ctx.IsSet("min_htlc_msat") {
 		req.MinHtlcMsat = ctx.Uint64("min_htlc_msat")
 		req.MinHtlcMsatSpecified = true

lnrpc/lightning.proto

@@ -4404,6 +4404,9 @@ message PolicyUpdateRequest {
 
     int32 inbound_base_fee_msat = 10;
     int32 inbound_fee_rate_ppm = 11;
+
+    // If true, inbound_base_fee_msat and inbound_fee_rate_ppm  are applied.
+    bool inbound_fee_specified = 12;
 }
 
 enum UpdateFailure {

lnrpc/lightning.swagger.json

@@ -6592,6 +6592,10 @@
         "inbound_fee_rate_ppm": {
           "type": "integer",
           "format": "int32"
+        },
+        "inbound_fee_specified": {
+          "type": "boolean",
+          "description": "If true, inbound_base_fee_msat and inbound_fee_rate_ppm  are applied."
         }
       }
     },

routing/localchans/manager.go

@@ -99,6 +99,16 @@ func (r *Manager) UpdatePolicy(newSchema routing.ChannelPolicy,
 			return nil
 		}
 
+		// extract the inbound fees from the edge we just updated.
+		var inboundFee lnwire.Fee
+		_, err = edge.ExtraOpaqueData.ExtractRecords(&inboundFee)
+		// We only handle chan policies of ourselves which works with
+		// or without specified inbound fees. So having a decoding error
+		// reveils another problem.
+		if err != nil {
+			return err
+		}
+
 		// Add updated edge to list of edges to send to gossiper.
 		edgesToUpdate = append(edgesToUpdate, discovery.EdgeWithInfo{
 			Info: info,
@@ -112,7 +122,9 @@ func (r *Manager) UpdatePolicy(newSchema routing.ChannelPolicy,
 			TimeLockDelta: uint32(edge.TimeLockDelta),
 			MinHTLCOut:    edge.MinHTLC,
 			MaxHTLC:       edge.MaxHTLC,
-			InboundFee:    newSchema.InboundFee,
+			InboundFee: models.NewInboundFeeFromWire(
+				inboundFee,
+			),
 		}
 
 		return nil
@@ -182,9 +194,14 @@ func (r *Manager) updateEdge(tx kvdb.RTx, chanPoint wire.OutPoint,
 		newSchema.FeeRate,
 	)
 
-	inboundFee := newSchema.InboundFee.ToWire()
-	if err := edge.ExtraOpaqueData.PackRecords(&inboundFee); err != nil {
-		return err
+	if !newSchema.InboundFee.IsNone() {
+		inboundFee := newSchema.InboundFee.UnsafeFromSome()
+		inboundWireFee := inboundFee.ToWire()
+
+		err := edge.ExtraOpaqueData.PackRecords(&inboundWireFee)
+		if err != nil {
+			return err
+		}
 	}
 
 	edge.TimeLockDelta = uint16(newSchema.TimeLockDelta)
@@ -215,9 +232,7 @@ func (r *Manager) updateEdge(tx kvdb.RTx, chanPoint wire.OutPoint,
 	}
 
 	// If a new min htlc is specified, update the edge.
-	if newSchema.MinHTLC != nil {
-		edge.MinHTLC = *newSchema.MinHTLC
-	}
+	edge.MinHTLC = newSchema.MinHTLC.UnwrapOr(edge.MinHTLC)
 
 	// If the MaxHtlc flag wasn't already set, we can set it now.
 	edge.MessageFlags |= lnwire.ChanUpdateRequiredMaxHtlc

routing/router.go

@@ -22,6 +22,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/clock"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/kvdb"
@@ -290,7 +291,7 @@ type FeeSchema struct {
 
 	// InboundFee is the inbound fee schedule that applies to forwards
 	// coming in through a channel to which this FeeSchema pertains.
-	InboundFee models.InboundFee
+	InboundFee fn.Option[models.InboundFee]
 }
 
 // ChannelPolicy holds the parameters that determine the policy we enforce
@@ -310,7 +311,7 @@ type ChannelPolicy struct {
 
 	// MinHTLC is the minimum HTLC size including fees we are allowed to
 	// forward over this channel.
-	MinHTLC *lnwire.MilliSatoshi
+	MinHTLC fn.Option[lnwire.MilliSatoshi]
 }
 
 // Config defines the configuration for the ChannelRouter. ALL elements within

rpcserver.go

@@ -46,6 +46,7 @@ import (
 	"github.com/lightningnetwork/lnd/contractcourt"
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/feature"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/funding"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/htlcswitch/hop"
@@ -7208,21 +7209,27 @@ func (r *rpcServer) UpdateChannelPolicy(ctx context.Context,
 		}
 	}
 
-	baseFeeMsat := lnwire.MilliSatoshi(req.BaseFeeMsat)
-	feeSchema := routing.FeeSchema{
-		BaseFee: baseFeeMsat,
-		FeeRate: feeRateFixed,
-		InboundFee: models.InboundFee{
+	// In case inbound fees are not specified no inbound fees will be
+	// applied but the previous value will be kept.
+	inboundFee := fn.None[models.InboundFee]()
+	if req.InboundFeeSpecified {
+		inboundFee = fn.Some(models.InboundFee{
 			Base: req.InboundBaseFeeMsat,
 			Rate: req.InboundFeeRatePpm,
-		},
+		})
+	}
+
+	baseFeeMsat := lnwire.MilliSatoshi(req.BaseFeeMsat)
+	feeSchema := routing.FeeSchema{
+		BaseFee:    baseFeeMsat,
+		FeeRate:    feeRateFixed,
+		InboundFee: inboundFee,
 	}
 
 	maxHtlc := lnwire.MilliSatoshi(req.MaxHtlcMsat)
-	var minHtlc *lnwire.MilliSatoshi
+	minHtlc := fn.None[lnwire.MilliSatoshi]()
 	if req.MinHtlcMsatSpecified {
-		min := lnwire.MilliSatoshi(req.MinHtlcMsat)
-		minHtlc = &min
+		minHtlc = fn.Some(lnwire.MilliSatoshi(req.MinHtlcMsat))
 	}
 
 	chanPolicy := routing.ChannelPolicy{