multi: do not use tlv.Record outside wire format handling

This commit prepares for more manipulation of custom records. A list of
tlv.Record types is more difficult to use than the more basic
map[uint64][]byte.

Furthermore fields and variables are renamed to make them more
consistent.

routing/pathfind.go

@@ -11,8 +11,8 @@ import (
 	"github.com/coreos/bbolt"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/route"
-	"github.com/lightningnetwork/lnd/tlv"
 )
 
 const (
@@ -100,7 +100,7 @@ type edgePolicyWithSource struct {
 func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex route.Vertex,
 	pathEdges []*channeldb.ChannelEdgePolicy, currentHeight uint32,
 	finalCLTVDelta uint16,
-	finalDestRecords []tlv.Record) (*route.Route, error) {
+	destCustomRecords record.CustomSet) (*route.Route, error) {
 
 	var (
 		hops []*route.Hop
@@ -198,8 +198,8 @@ func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex route.Vertex,
 
 		// If this is the last hop, then we'll populate any TLV records
 		// destined for it.
-		if i == len(pathEdges)-1 && len(finalDestRecords) != 0 {
-			currentHop.TLVRecords = finalDestRecords
+		if i == len(pathEdges)-1 && len(destCustomRecords) != 0 {
+			currentHop.CustomRecords = destCustomRecords
 		}
 
 		hops = append([]*route.Hop{currentHop}, hops...)

routing/payment_session.go

@@ -129,7 +129,7 @@ func (p *paymentSession) RequestRoute(payment *LightningPayment,
 	sourceVertex := route.Vertex(ss.SelfNode.PubKeyBytes)
 	route, err := newRoute(
 		payment.Amount, sourceVertex, path, height, finalCltvDelta,
-		payment.FinalDestRecords,
+		payment.DestCustomRecords,
 	)
 	if err != nil {
 		// TODO(roasbeef): return which edge/vertex didn't work

routing/route/route.go

@@ -107,9 +107,9 @@ type Hop struct {
 	// only be set for the final hop.
 	MPP *record.MPP
 
-	// TLVRecords if non-nil are a set of additional TLV records that
+	// CustomRecords if non-nil are a set of additional TLV records that
 	// should be included in the forwarding instructions for this node.
-	TLVRecords []tlv.Record
+	CustomRecords record.CustomSet
 
 	// LegacyPayload if true, then this signals that this node doesn't
 	// understand the new TLV payload, so we must instead use the legacy
@@ -165,7 +165,8 @@ func (h *Hop) PackHopPayload(w io.Writer, nextChanID uint64) error {
 	}
 
 	// Append any custom types destined for this hop.
-	records = append(records, h.TLVRecords...)
+	tlvRecords := tlv.MapToRecords(h.CustomRecords)
+	records = append(records, tlvRecords...)
 
 	// To ensure we produce a canonical stream, we'll sort the records
 	// before encoding them as a stream in the hop payload.

routing/router.go

@@ -24,10 +24,10 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/chanvalidate"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/multimutex"
+	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/chainview"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/lightningnetwork/lnd/ticker"
-	"github.com/lightningnetwork/lnd/tlv"
 	"github.com/lightningnetwork/lnd/zpay32"
 )
 
@@ -1401,7 +1401,7 @@ type routingMsg struct {
 // factoring in channel capacities and cumulative fees along the route.
 func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 	amt lnwire.MilliSatoshi, restrictions *RestrictParams,
-	destTlvRecords []tlv.Record,
+	destCustomRecords record.CustomSet,
 	finalExpiry ...uint16) (*route.Route, error) {
 
 	var finalCLTVDelta uint16
@@ -1455,7 +1455,7 @@ func (r *ChannelRouter) FindRoute(source, target route.Vertex,
 	// Create the route with absolute time lock values.
 	route, err := newRoute(
 		amt, source, path, uint32(currentHeight), finalCLTVDelta,
-		destTlvRecords,
+		destCustomRecords,
 	)
 	if err != nil {
 		return nil, err
@@ -1608,11 +1608,11 @@ type LightningPayment struct {
 	// attempting to complete.
 	PaymentRequest []byte
 
-	// FinalDestRecords are TLV records that are to be sent to the final
+	// DestCustomRecords are TLV records that are to be sent to the final
 	// hop in the new onion payload format. If the destination does not
 	// understand this new onion payload format, then the payment will
 	// fail.
-	FinalDestRecords []tlv.Record
+	DestCustomRecords record.CustomSet
 }
 
 // SendPayment attempts to send a payment as described within the passed