routing/pathfind: evaluate TLV support sooner

We move up the check for TLV support, since we will later use it to
determine if we can use dependent features, e.g. TLV records and payment
addresses.

routing/pathfind.go

@@ -150,7 +150,22 @@ func newRoute(sourceVertex route.Vertex,
 			amtToForward     lnwire.MilliSatoshi
 			fee              lnwire.MilliSatoshi
 			outgoingTimeLock uint32
+			tlvPayload       bool
 		)
+
+		// Define a helper function that checks this edge's feature
+		// vector for support for a given feature. We assume at this
+		// point that the feature vectors transitive dependencies have
+		// been validated.
+		supports := edge.Node.Features.HasFeature
+
+		// 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
@@ -194,19 +209,7 @@ func newRoute(sourceVertex route.Vertex,
 			ChannelID:        edge.ChannelID,
 			AmtToForward:     amtToForward,
 			OutgoingTimeLock: outgoingTimeLock,
-			LegacyPayload:    true,
-		}
-
-		// We start out above by assuming that this node needs the
-		// legacy payload, as if we don't have the full
-		// NodeAnnouncement information for this node, then we can't
-		// assume it knows the latest features. If we do have a feature
-		// vector for this node, then we'll update the info now.
-		if edge.Node.Features != nil {
-			features := edge.Node.Features
-			currentHop.LegacyPayload = !features.HasFeature(
-				lnwire.TLVOnionPayloadOptional,
-			)
+			LegacyPayload:    !tlvPayload,
 		}
 
 		// If this is the last hop, then we'll populate any TLV records