routing: encode first hop records in update_add_htlc message

routing/payment_lifecycle.go

@@ -1,6 +1,7 @@
 package routing
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"time"
@@ -13,8 +14,10 @@ import (
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/lightningnetwork/lnd/routing/shards"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 // ErrPaymentLifecycleExiting is used when waiting for htlc attempt result, but
@@ -31,6 +34,7 @@ type paymentLifecycle struct {
 	shardTracker  shards.ShardTracker
 	timeoutChan   <-chan time.Time
 	currentHeight int32
+	firstHopTLVs  record.CustomSet
 
 	// quit is closed to signal the sub goroutines of the payment lifecycle
 	// to stop.
@@ -53,7 +57,7 @@ type paymentLifecycle struct {
 func newPaymentLifecycle(r *ChannelRouter, feeLimit lnwire.MilliSatoshi,
 	identifier lntypes.Hash, paySession PaymentSession,
 	shardTracker shards.ShardTracker, timeout time.Duration,
-	currentHeight int32) *paymentLifecycle {
+	currentHeight int32, firstHopTLVs record.CustomSet) *paymentLifecycle {
 
 	p := &paymentLifecycle{
 		router:          r,
@@ -64,6 +68,7 @@ func newPaymentLifecycle(r *ChannelRouter, feeLimit lnwire.MilliSatoshi,
 		currentHeight:   currentHeight,
 		quit:            make(chan struct{}),
 		resultCollected: make(chan error, 1),
+		firstHopTLVs:    firstHopTLVs,
 	}
 
 	// Mount the result collector.
@@ -673,6 +678,18 @@ func (p *paymentLifecycle) sendAttempt(
 		PaymentHash: *attempt.Hash,
 	}
 
+	buffer := new(bytes.Buffer)
+	if err := p.firstHopTLVs.Encode(buffer); err != nil {
+		return p.failAttempt(attempt.AttemptID, err)
+	}
+
+	recordsBytes := buffer.Bytes()
+	tlvRecord := tlv.NewPrimitiveRecord[lnwire.CustomRecordsBlobTlvType](
+		recordsBytes,
+	)
+
+	htlcAdd.CustomRecordsBlob = tlv.SomeRecordT(tlvRecord)
+
 	// Generate the raw encoded sphinx packet to be included along
 	// with the htlcAdd message that we send directly to the
 	// switch.

routing/router.go

@@ -713,7 +713,7 @@ func (r *ChannelRouter) Start() error {
 			// be tried.
 			_, _, err := r.sendPayment(
 				0, payment.Info.PaymentIdentifier, 0,
-				paySession, shardTracker,
+				paySession, shardTracker, nil,
 			)
 			if err != nil {
 				log.Errorf("Resuming payment %v failed: %v.",
@@ -2308,6 +2308,11 @@ type LightningPayment struct {
 	// fail.
 	DestCustomRecords record.CustomSet
 
+	// FirstHopCustomRecords are the TLV records that are to be sent to the
+	// first hop of this payment. These records will be transmitted via the
+	// wire message and therefore do not affect the onion payload size.
+	FirstHopCustomRecords record.CustomSet
+
 	// MaxParts is the maximum number of partial payments that may be used
 	// to complete the full amount.
 	MaxParts uint32
@@ -2393,6 +2398,7 @@ func (r *ChannelRouter) SendPayment(payment *LightningPayment) ([32]byte,
 	return r.sendPayment(
 		payment.FeeLimit, payment.Identifier(),
 		payment.PayAttemptTimeout, paySession, shardTracker,
+		payment.FirstHopCustomRecords,
 	)
 }
 
@@ -2413,6 +2419,7 @@ func (r *ChannelRouter) SendPaymentAsync(payment *LightningPayment,
 		_, _, err := r.sendPayment(
 			payment.FeeLimit, payment.Identifier(),
 			payment.PayAttemptTimeout, ps, st,
+			payment.FirstHopCustomRecords,
 		)
 		if err != nil {
 			log.Errorf("Payment %x failed: %v",
@@ -2587,7 +2594,7 @@ func (r *ChannelRouter) sendToRoute(htlcHash lntypes.Hash, rt *route.Route,
 	// - no payment timeout.
 	// - no current block height.
 	p := newPaymentLifecycle(
-		r, 0, paymentIdentifier, nil, shardTracker, 0, 0,
+		r, 0, paymentIdentifier, nil, shardTracker, 0, 0, nil,
 	)
 
 	// We found a route to try, create a new HTLC attempt to try.
@@ -2683,8 +2690,8 @@ func (r *ChannelRouter) sendToRoute(htlcHash lntypes.Hash, rt *route.Route,
 // the ControlTower.
 func (r *ChannelRouter) sendPayment(feeLimit lnwire.MilliSatoshi,
 	identifier lntypes.Hash, timeout time.Duration,
-	paySession PaymentSession,
-	shardTracker shards.ShardTracker) ([32]byte, *route.Route, error) {
+	paySession PaymentSession, shardTracker shards.ShardTracker,
+	firstHopTLVs record.CustomSet) ([32]byte, *route.Route, error) {
 
 	// We'll also fetch the current block height so we can properly
 	// calculate the required HTLC time locks within the route.
@@ -2697,7 +2704,7 @@ func (r *ChannelRouter) sendPayment(feeLimit lnwire.MilliSatoshi,
 	// can resume the payment from the current state.
 	p := newPaymentLifecycle(
 		r, feeLimit, identifier, paySession,
-		shardTracker, timeout, currentHeight,
+		shardTracker, timeout, currentHeight, firstHopTLVs,
 	)
 
 	return p.resumePayment()