graph+rpcserver: add InboundFee to ChannelEdgeUpdate

And then use that new field instead of parsing from extra opaque data.

graph/db/notifications.go

@@ -12,6 +12,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/go-errors/errors"
+	"github.com/lightningnetwork/lnd/fn/v2"
 	"github.com/lightningnetwork/lnd/graph/db/models"
 	"github.com/lightningnetwork/lnd/lnutils"
 	"github.com/lightningnetwork/lnd/lnwire"
@@ -360,6 +361,9 @@ type ChannelEdgeUpdate struct {
 	// payments.
 	Disabled bool
 
+	// InboundFee is the fee that must be paid for incoming HTLCs.
+	InboundFee fn.Option[lnwire.Fee]
+
 	// ExtraOpaqueData is the set of data that was appended to this message
 	// to fill out the full maximum transport message size. These fields can
 	// be used to specify optional data such as custom TLV fields.
@@ -442,6 +446,7 @@ func (c *ChannelGraph) addToTopologyChange(update *TopologyChange,
 			AdvertisingNode: aNode,
 			ConnectingNode:  cNode,
 			Disabled:        m.ChannelFlags&lnwire.ChanUpdateDisabled != 0,
+			InboundFee:      m.InboundFee,
 			ExtraOpaqueData: m.ExtraOpaqueData,
 		}
 

rpcserver.go

@@ -6776,23 +6776,6 @@ func marshalExtraOpaqueData(data []byte) map[uint64][]byte {
 	return records
 }
 
-// extractInboundFeeSafe tries to extract the inbound fee from the given extra
-// opaque data tlv block. If parsing fails, a zero inbound fee is returned. This
-// function is typically used on unvalidated data coming stored in the database.
-// There is not much we can do other than ignoring errors here.
-func extractInboundFeeSafe(data lnwire.ExtraOpaqueData) lnwire.Fee {
-	var inboundFee lnwire.Fee
-
-	_, err := data.ExtractRecords(&inboundFee)
-	if err != nil {
-		// Return zero fee. Do not return the inboundFee variable
-		// because it may be undefined.
-		return lnwire.Fee{}
-	}
-
-	return inboundFee
-}
-
 func marshalDBEdge(edgeInfo *models.ChannelEdgeInfo,
 	c1, c2 *models.ChannelEdgePolicy) *lnrpc.ChannelEdge {
 
@@ -7349,9 +7332,7 @@ func marshallTopologyChange(
 		customRecords := marshalExtraOpaqueData(
 			channelUpdate.ExtraOpaqueData,
 		)
-		inboundFee := extractInboundFeeSafe(
-			channelUpdate.ExtraOpaqueData,
-		)
+		inboundFee := channelUpdate.InboundFee.UnwrapOr(lnwire.Fee{})
 
 		channelUpdates[i] = &lnrpc.ChannelEdgeUpdate{
 			ChanId: channelUpdate.ChanID,