channeldb+routing: persist first hop custom records

With this commit we make sure the first hop custom records aren't lost
on restart/resume of a payment, so we persist it as part of the
PaymentCreationInfo struct.

channeldb/payments.go

@@ -195,6 +195,11 @@ type PaymentCreationInfo struct {
 
 	// PaymentRequest is the full payment request, if any.
 	PaymentRequest []byte
+
+	// 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 only and therefore do not affect the onion payload size.
+	FirstHopCustomRecords lnwire.CustomRecords
 }
 
 // htlcBucketKey creates a composite key from prefix and id where the result is
@@ -1010,10 +1015,21 @@ func serializePaymentCreationInfo(w io.Writer, c *PaymentCreationInfo) error {
 		return err
 	}
 
+	// Any remaining bytes are TLV encoded records. Currently, these are
+	// only the custom records provided by the user to be sent to the first
+	// hop. But this can easily be extended with further records by merging
+	// the records into a single TLV stream.
+	err := c.FirstHopCustomRecords.SerializeTo(w)
+	if err != nil {
+		return err
+	}
+
 	return nil
 }
 
-func deserializePaymentCreationInfo(r io.Reader) (*PaymentCreationInfo, error) {
+func deserializePaymentCreationInfo(r io.Reader) (*PaymentCreationInfo,
+	error) {
+
 	var scratch [8]byte
 
 	c := &PaymentCreationInfo{}
@@ -1046,6 +1062,15 @@ func deserializePaymentCreationInfo(r io.Reader) (*PaymentCreationInfo, error) {
 	}
 	c.PaymentRequest = payReq
 
+	// Any remaining bytes are TLV encoded records. Currently, these are
+	// only the custom records provided by the user to be sent to the first
+	// hop. But this can easily be extended with further records by merging
+	// the records into a single TLV stream.
+	c.FirstHopCustomRecords, err = lnwire.ParseCustomRecordsFrom(r)
+	if err != nil {
+		return nil, err
+	}
+
 	return c, nil
 }
 

channeldb/payments_test.go

@@ -13,6 +13,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"github.com/stretchr/testify/require"
@@ -108,7 +109,7 @@ func makeFakeInfo() (*PaymentCreationInfo, *HTLCAttemptInfo) {
 		// Use single second precision to avoid false positive test
 		// failures due to the monotonic time component.
 		CreationTime:   time.Unix(time.Now().Unix(), 0),
-		PaymentRequest: []byte(""),
+		PaymentRequest: []byte("test"),
 	}
 
 	a := NewHtlcAttempt(
@@ -124,36 +125,40 @@ func TestSentPaymentSerialization(t *testing.T) {
 	c, s := makeFakeInfo()
 
 	var b bytes.Buffer
-	if err := serializePaymentCreationInfo(&b, c); err != nil {
-		t.Fatalf("unable to serialize creation info: %v", err)
-	}
+	require.NoError(t, serializePaymentCreationInfo(&b, c), "serialize")
+
+	// Assert the length of the serialized creation info is as expected,
+	// without any custom records.
+	baseLength := 32 + 8 + 8 + 4 + len(c.PaymentRequest)
+	require.Len(t, b.Bytes(), baseLength)
 
 	newCreationInfo, err := deserializePaymentCreationInfo(&b)
-	require.NoError(t, err, "unable to deserialize creation info")
-
-	if !reflect.DeepEqual(c, newCreationInfo) {
-		t.Fatalf("Payments do not match after "+
-			"serialization/deserialization %v vs %v",
-			spew.Sdump(c), spew.Sdump(newCreationInfo),
-		)
-	}
+	require.NoError(t, err, "deserialize")
+	require.Equal(t, c, newCreationInfo)
 
 	b.Reset()
-	if err := serializeHTLCAttemptInfo(&b, s); err != nil {
-		t.Fatalf("unable to serialize info: %v", err)
+
+	// Now we add some custom records to the creation info and serialize it
+	// again.
+	c.FirstHopCustomRecords = lnwire.CustomRecords{
+		lnwire.MinCustomRecordsTlvType: []byte{1, 2, 3},
 	}
+	require.NoError(t, serializePaymentCreationInfo(&b, c), "serialize")
+
+	newCreationInfo, err = deserializePaymentCreationInfo(&b)
+	require.NoError(t, err, "deserialize")
+	require.Equal(t, c, newCreationInfo)
+
+	require.NoError(t, serializeHTLCAttemptInfo(&b, s), "serialize")
 
 	newWireInfo, err := deserializeHTLCAttemptInfo(&b)
-	require.NoError(t, err, "unable to deserialize info")
+	require.NoError(t, err, "deserialize")
 	newWireInfo.AttemptID = s.AttemptID
 
-	// First we verify all the records match up porperly, as they aren't
+	// First we verify all the records match up properly, as they aren't
 	// able to be properly compared using reflect.DeepEqual.
 	err = assertRouteEqual(&s.Route, &newWireInfo.Route)
-	if err != nil {
-		t.Fatalf("Routes do not match after "+
-			"serialization/deserialization: %v", err)
-	}
+	require.NoError(t, err)
 
 	// Clear routes to allow DeepEqual to compare the remaining fields.
 	newWireInfo.Route = route.Route{}
@@ -163,12 +168,7 @@ func TestSentPaymentSerialization(t *testing.T) {
 	// DeepEqual, and assert that our key equals the original key.
 	require.Equal(t, s.cachedSessionKey, newWireInfo.SessionKey())
 
-	if !reflect.DeepEqual(s, newWireInfo) {
-		t.Fatalf("Payments do not match after "+
-			"serialization/deserialization %v vs %v",
-			spew.Sdump(s), spew.Sdump(newWireInfo),
-		)
-	}
+	require.Equal(t, s, newWireInfo)
 }
 
 // assertRouteEquals compares to routes for equality and returns an error if

routing/router.go

@@ -1022,10 +1022,11 @@ func (r *ChannelRouter) PreparePayment(payment *LightningPayment) (
 	//
 	// TODO(roasbeef): store records as part of creation info?
 	info := &channeldb.PaymentCreationInfo{
-		PaymentIdentifier: payment.Identifier(),
-		Value:             payment.Amount,
-		CreationTime:      r.cfg.Clock.Now(),
-		PaymentRequest:    payment.PaymentRequest,
+		PaymentIdentifier:     payment.Identifier(),
+		Value:                 payment.Amount,
+		CreationTime:          r.cfg.Clock.Now(),
+		PaymentRequest:        payment.PaymentRequest,
+		FirstHopCustomRecords: payment.FirstHopCustomRecords,
 	}
 
 	// Create a new ShardTracker that we'll use during the life cycle of
@@ -1120,10 +1121,11 @@ func (r *ChannelRouter) sendToRoute(htlcHash lntypes.Hash, rt *route.Route,
 	// Record this payment hash with the ControlTower, ensuring it is not
 	// already in-flight.
 	info := &channeldb.PaymentCreationInfo{
-		PaymentIdentifier: paymentIdentifier,
-		Value:             amt,
-		CreationTime:      r.cfg.Clock.Now(),
-		PaymentRequest:    nil,
+		PaymentIdentifier:     paymentIdentifier,
+		Value:                 amt,
+		CreationTime:          r.cfg.Clock.Now(),
+		PaymentRequest:        nil,
+		FirstHopCustomRecords: firstHopCustomRecords,
 	}
 
 	err := r.cfg.Control.InitPayment(paymentIdentifier, info)
@@ -1483,7 +1485,7 @@ func (r *ChannelRouter) resumePayments() error {
 		noTimeout := time.Duration(0)
 		_, _, err := r.sendPayment(
 			context.Background(), 0, payHash, noTimeout, paySession,
-			shardTracker, nil,
+			shardTracker, payment.Info.FirstHopCustomRecords,
 		)
 		if err != nil {
 			log.Errorf("Resuming payment %v failed: %v", payHash,