refactor+multi: use *lnwire.FeatureVector for ChannelEdgeInfo features

In this commit, we move the serialisation details of a channel's
features to the DB layer and change the `models` field to instead use a
more useful `*lnwire.FeatureVector` type.

This makes the features easier to work with and moves the serialisation
to where it is actually used.

graph/db/graph_test.go

@@ -416,6 +416,7 @@ func TestEdgeInsertionDeletion(t *testing.T) {
 			BitcoinSig1Bytes: testSig.Serialize(),
 			BitcoinSig2Bytes: testSig.Serialize(),
 		},
+		Features:     lnwire.EmptyFeatureVector(),
 		ChannelPoint: outpoint,
 		Capacity:     9000,
 	}
@@ -479,12 +480,6 @@ func createEdge(height, txIndex uint32, txPosition uint16, outPointIndex uint32,
 		Index: outPointIndex,
 	}
 
-	var (
-		features   = lnwire.NewRawFeatureVector()
-		featureBuf bytes.Buffer
-	)
-	_ = features.Encode(&featureBuf)
-
 	node1Pub, _ := node1.PubKey()
 	node2Pub, _ := node2.PubKey()
 	edgeInfo := models.ChannelEdgeInfo{
@@ -499,7 +494,7 @@ func createEdge(height, txIndex uint32, txPosition uint16, outPointIndex uint32,
 		ChannelPoint:    outpoint,
 		Capacity:        9000,
 		ExtraOpaqueData: make([]byte, 0),
-		Features:        featureBuf.Bytes(),
+		Features:        lnwire.EmptyFeatureVector(),
 	}
 
 	copy(edgeInfo.NodeKey1Bytes[:], node1Pub.SerializeCompressed())
@@ -663,8 +658,8 @@ func assertEdgeInfoEqual(t *testing.T, e1 *models.ChannelEdgeInfo,
 		t.Fatalf("bitcoinkey2 doesn't match")
 	}
 
-	if !bytes.Equal(e1.Features, e2.Features) {
-		t.Fatalf("features doesn't match: %x vs %x", e1.Features,
+	if !e1.Features.Equals(e2.Features.RawFeatureVector) {
+		t.Fatalf("features don't match: %v vs %v", e1.Features,
 			e2.Features)
 	}
 
@@ -741,12 +736,6 @@ func createChannelEdge(node1, node2 *models.LightningNode,
 		Index: prand.Uint32(),
 	}
 
-	var (
-		features   = lnwire.NewRawFeatureVector()
-		featureBuf bytes.Buffer
-	)
-	_ = features.Encode(&featureBuf)
-
 	// Add the new edge to the database, this should proceed without any
 	// errors.
 	edgeInfo := &models.ChannelEdgeInfo{
@@ -759,7 +748,7 @@ func createChannelEdge(node1, node2 *models.LightningNode,
 			2, 2, 2, 2,
 			3, 3, 3, 3, 3,
 		},
-		Features: featureBuf.Bytes(),
+		Features: lnwire.EmptyFeatureVector(),
 	}
 	copy(edgeInfo.NodeKey1Bytes[:], firstNode[:])
 	copy(edgeInfo.NodeKey2Bytes[:], secondNode[:])
@@ -1617,6 +1606,7 @@ func fillTestGraph(t testing.TB, graph *ChannelGraph, numNodes,
 					BitcoinSig1Bytes: testSig.Serialize(),
 					BitcoinSig2Bytes: testSig.Serialize(),
 				},
+				Features:     lnwire.EmptyFeatureVector(),
 				ChannelPoint: op,
 				Capacity:     1000,
 			}
@@ -1799,6 +1789,7 @@ func TestGraphPruning(t *testing.T) {
 				BitcoinSig1Bytes: testSig.Serialize(),
 				BitcoinSig2Bytes: testSig.Serialize(),
 			},
+			Features:     lnwire.EmptyFeatureVector(),
 			ChannelPoint: op,
 			Capacity:     1000,
 		}

graph/db/kv_store.go

@@ -4291,7 +4291,12 @@ func putChanEdgeInfo(edgeIndex kvdb.RwBucket,
 		return err
 	}
 
-	if err := wire.WriteVarBytes(&b, 0, edgeInfo.Features); err != nil {
+	var featureBuf bytes.Buffer
+	if err := edgeInfo.Features.Encode(&featureBuf); err != nil {
+		return fmt.Errorf("unable to encode features: %w", err)
+	}
+
+	if err := wire.WriteVarBytes(&b, 0, featureBuf.Bytes()); err != nil {
 		return err
 	}
 
@@ -4374,11 +4379,19 @@ func deserializeChanEdgeInfo(r io.Reader) (models.ChannelEdgeInfo, error) {
 		return models.ChannelEdgeInfo{}, err
 	}
 
-	edgeInfo.Features, err = wire.ReadVarBytes(r, 0, 900, "features")
+	featureBytes, err := wire.ReadVarBytes(r, 0, 900, "features")
 	if err != nil {
 		return models.ChannelEdgeInfo{}, err
 	}
 
+	features := lnwire.NewRawFeatureVector()
+	err = features.Decode(bytes.NewReader(featureBytes))
+	if err != nil {
+		return models.ChannelEdgeInfo{}, fmt.Errorf("unable to decode "+
+			"features: %w", err)
+	}
+	edgeInfo.Features = lnwire.NewFeatureVector(features, lnwire.Features)
+
 	proof := &models.ChannelAuthProof{}
 
 	proof.NodeSig1Bytes, err = wire.ReadVarBytes(r, 0, 80, "sigs")

graph/db/models/channel_edge_info.go

@@ -9,6 +9,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/fn/v2"
+	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // ChannelEdgeInfo represents a fully authenticated channel along with all its
@@ -46,9 +47,9 @@ type ChannelEdgeInfo struct {
 	BitcoinKey2Bytes [33]byte
 	bitcoinKey2      *btcec.PublicKey
 
-	// Features is an opaque byte slice that encodes the set of channel
-	// specific features that this channel edge supports.
-	Features []byte
+	// Features is the list of protocol features supported by this channel
+	// edge.
+	Features *lnwire.FeatureVector
 
 	// AuthProof is the authentication proof for this channel. This proof
 	// contains a set of signatures binding four identities, which attests

graph/db/sql_store.go

@@ -3833,26 +3833,16 @@ func insertChannel(ctx context.Context, db SQLQueries,
 	}
 
 	// Insert any channel features.
-	if len(edge.Features) != 0 {
-		chanFeatures := lnwire.NewRawFeatureVector()
-		err := chanFeatures.Decode(bytes.NewReader(edge.Features))
+	for feature := range edge.Features.Features() {
+		err = db.InsertChannelFeature(
+			ctx, sqlc.InsertChannelFeatureParams{
+				ChannelID:  dbChanID,
+				FeatureBit: int32(feature),
+			},
+		)
 		if err != nil {
-			return nil, err
-		}
-
-		fv := lnwire.NewFeatureVector(chanFeatures, lnwire.Features)
-		for feature := range fv.Features() {
-			err = db.InsertChannelFeature(
-				ctx, sqlc.InsertChannelFeatureParams{
-					ChannelID:  dbChanID,
-					FeatureBit: int32(feature),
-				},
-			)
-			if err != nil {
-				return nil, fmt.Errorf("unable to insert "+
-					"channel(%d) feature(%v): %w", dbChanID,
-					feature, err)
-			}
+			return nil, fmt.Errorf("unable to insert channel(%d) "+
+				"feature(%v): %w", dbChanID, feature, err)
 		}
 	}
 
@@ -3975,11 +3965,6 @@ func getAndBuildEdgeInfo(ctx context.Context, db SQLQueries,
 		return nil, err
 	}
 
-	var featureBuf bytes.Buffer
-	if err := fv.Encode(&featureBuf); err != nil {
-		return nil, fmt.Errorf("unable to encode features: %w", err)
-	}
-
 	recs, err := lnwire.CustomRecords(extras).Serialize()
 	if err != nil {
 		return nil, fmt.Errorf("unable to serialize extra signed "+
@@ -4002,7 +3987,7 @@ func getAndBuildEdgeInfo(ctx context.Context, db SQLQueries,
 		BitcoinKey2Bytes: btcKey2,
 		ChannelPoint:     *op,
 		Capacity:         btcutil.Amount(dbChan.Capacity.Int64),
-		Features:         featureBuf.Bytes(),
+		Features:         fv,
 		ExtraOpaqueData:  recs,
 	}