routing: assume TLV onion during route construction

routing/pathfind.go

@@ -163,7 +163,6 @@ func newRoute(sourceVertex route.Vertex,
 			fee                 int64
 			totalAmtMsatBlinded lnwire.MilliSatoshi
 			outgoingTimeLock    uint32
-			tlvPayload          bool
 			customRecords       record.CustomSet
 			mpp                 *record.MPP
 			metadata            []byte
@@ -182,13 +181,6 @@ func newRoute(sourceVertex route.Vertex,
 			return edge.ToNodeFeatures.HasFeature(feature)
 		}
 
-		// We start by assuming the node doesn't support TLV. We'll now
-		// inspect the node's feature vector to see if we can promote
-		// the hop. We assume already that the feature vector's
-		// transitive dependencies have already been validated by path
-		// finding or some other means.
-		tlvPayload = supports(lnwire.TLVOnionPayloadOptional)
-
 		if i == len(pathEdges)-1 {
 			// If this is the last hop, then the hop payload will
 			// contain the exact amount. In BOLT #4: Onion Routing
@@ -206,12 +198,7 @@ func newRoute(sourceVertex route.Vertex,
 			totalTimeLock += uint32(finalHop.cltvDelta)
 			outgoingTimeLock = totalTimeLock
 
-			// Attach any custom records to the final hop if the
-			// receiver supports TLV.
-			if !tlvPayload && finalHop.records != nil {
-				return nil, errors.New("cannot attach " +
-					"custom records")
-			}
+			// Attach any custom records to the final hop.
 			customRecords = finalHop.records
 
 			// If we're attaching a payment addr but the receiver
@@ -277,7 +264,6 @@ func newRoute(sourceVertex route.Vertex,
 			ChannelID:        edge.ChannelID,
 			AmtToForward:     amtToForward,
 			OutgoingTimeLock: outgoingTimeLock,
-			LegacyPayload:    !tlvPayload,
 			CustomRecords:    customRecords,
 			MPP:              mpp,
 			Metadata:         metadata,

routing/pathfind_test.go

@@ -3,7 +3,6 @@ package routing
 import (
 	"bytes"
 	"crypto/sha256"
-	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
 	"errors"
@@ -25,6 +24,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/htlcswitch"
+	switchhop "github.com/lightningnetwork/lnd/htlcswitch/hop"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/record"
@@ -1030,7 +1030,8 @@ var basicGraphPathFindingTests = []basicGraphPathFindingTestCase{
 	// Basic route with fee limit.
 	{target: "sophon", paymentAmt: 100, feeLimit: 50,
 		expectFailureNoPath: true,
-	}}
+	},
+}
 
 func runBasicGraphPathFinding(t *testing.T, useCache bool) {
 	testGraphInstance, err := parseTestGraph(t, useCache, basicGraphFilePath)
@@ -1123,32 +1124,27 @@ func testBasicGraphPathFindingCase(t *testing.T, graphInstance *testGraphInstanc
 
 	// Hops should point to the next hop
 	for i := 0; i < len(expectedHops)-1; i++ {
-		var expectedHop [8]byte
-		binary.BigEndian.PutUint64(expectedHop[:], route.Hops[i+1].ChannelID)
+		payload, _, err := switchhop.ParseTLVPayload(
+			bytes.NewReader(sphinxPath[i].HopPayload.Payload),
+		)
+		require.NoError(t, err)
 
-		hopData, err := sphinxPath[i].HopPayload.HopData()
-		if err != nil {
-			t.Fatalf("unable to make hop data: %v", err)
-		}
-
-		if !bytes.Equal(hopData.NextAddress[:], expectedHop[:]) {
-			t.Fatalf("first hop has incorrect next hop: expected %x, got %x",
-				expectedHop[:], hopData.NextAddress[:])
-		}
+		require.Equal(
+			t, route.Hops[i+1].ChannelID,
+			payload.FwdInfo.NextHop.ToUint64(),
+		)
 	}
 
+	lastHopIndex := len(expectedHops) - 1
+
+	payload, _, err := switchhop.ParseTLVPayload(
+		bytes.NewReader(sphinxPath[lastHopIndex].HopPayload.Payload),
+	)
+	require.NoError(t, err)
+
 	// The final hop should have a next hop value of all zeroes in order
 	// to indicate it's the exit hop.
-	var exitHop [8]byte
-	lastHopIndex := len(expectedHops) - 1
-
-	hopData, err := sphinxPath[lastHopIndex].HopPayload.HopData()
-	require.NoError(t, err, "unable to create hop data")
-
-	if !bytes.Equal(hopData.NextAddress[:], exitHop[:]) {
-		t.Fatalf("first hop has incorrect next hop: expected %x, got %x",
-			exitHop[:], hopData.NextAddress)
-	}
+	require.Zero(t, payload.FwdInfo.NextHop.ToUint64())
 
 	var expectedTotalFee lnwire.MilliSatoshi
 	for i := 0; i < expectedHopCount; i++ {