lnwallet: add TLV blob to PaymentDescriptor + htlc add

In this commit, we add a TLV blob to the PaymentDescriptor struct. We also now thread through this value from the UpdateAddHTLC message to the PaymentDescriptor mapping, and the other way around.

channeldb/channel.go

@@ -2580,6 +2580,12 @@ type HTLC struct {
 	// HTLC. It is stored in the ExtraData field, which is used to store
 	// a TLV stream of additional information associated with the HTLC.
 	BlindingPoint lnwire.BlindingPointRecord
+
+	// CustomRecords is a set of custom TLV records that are associated with
+	// this HTLC. These records are used to store additional information
+	// about the HTLC that is not part of the standard HTLC fields. This
+	// field is encoded within the ExtraData field.
+	CustomRecords lnwire.CustomRecords
 }
 
 // serializeExtraData encodes a TLV stream of extra data to be stored with a
@@ -2598,6 +2604,11 @@ func (h *HTLC) serializeExtraData() error {
 		records = append(records, &b)
 	})
 
+	records, err := h.CustomRecords.ExtendRecordProducers(records)
+	if err != nil {
+		return err
+	}
+
 	return h.ExtraData.PackRecords(records...)
 }
 
@@ -2619,8 +2630,19 @@ func (h *HTLC) deserializeExtraData() error {
 
 	if val, ok := tlvMap[h.BlindingPoint.TlvType()]; ok && val == nil {
 		h.BlindingPoint = tlv.SomeRecordT(blindingPoint)
+
+		// Remove the entry from the TLV map. Anything left in the map
+		// will be included in the custom records field.
+		delete(tlvMap, h.BlindingPoint.TlvType())
 	}
 
+	// Set the custom records field to the remaining TLV records.
+	customRecords, err := lnwire.NewCustomRecords(tlvMap)
+	if err != nil {
+		return err
+	}
+	h.CustomRecords = customRecords
+
 	return nil
 }
 
@@ -2758,6 +2780,8 @@ func (h *HTLC) Copy() HTLC {
 	copy(clone.Signature[:], h.Signature)
 	copy(clone.RHash[:], h.RHash[:])
 	copy(clone.ExtraData, h.ExtraData)
+	clone.BlindingPoint = h.BlindingPoint
+	clone.CustomRecords = h.CustomRecords.Copy()
 
 	return clone
 }

channeldb/channel_test.go

@@ -1657,6 +1657,24 @@ func TestHTLCsExtraData(t *testing.T) {
 		),
 	}
 
+	// Custom channel data htlc with a blinding point.
+	customDataHTLC := HTLC{
+		Signature:     testSig.Serialize(),
+		Incoming:      false,
+		Amt:           10,
+		RHash:         key,
+		RefundTimeout: 1,
+		OnionBlob:     lnmock.MockOnion(),
+		BlindingPoint: tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
+				pubKey,
+			),
+		),
+		CustomRecords: map[uint64][]byte{
+			uint64(lnwire.MinCustomRecordsTlvType + 3): {1, 2, 3},
+		},
+	}
+
 	testCases := []struct {
 		name        string
 		htlcs       []HTLC
@@ -1678,6 +1696,7 @@ func TestHTLCsExtraData(t *testing.T) {
 				mockHtlc,
 				blindingPointHTLC,
 				mockHtlc,
+				customDataHTLC,
 			},
 		},
 	}

lnwallet/channel.go

@@ -529,6 +529,7 @@ func (c *commitment) toDiskCommit(
 			LogIndex:      htlc.LogIndex,
 			Incoming:      false,
 			BlindingPoint: htlc.BlindingPoint,
+			CustomRecords: htlc.CustomRecords.Copy(),
 		}
 		copy(h.OnionBlob[:], htlc.OnionBlob)
 
@@ -554,8 +555,10 @@ func (c *commitment) toDiskCommit(
 			LogIndex:      htlc.LogIndex,
 			Incoming:      true,
 			BlindingPoint: htlc.BlindingPoint,
+			CustomRecords: htlc.CustomRecords.Copy(),
 		}
 		copy(h.OnionBlob[:], htlc.OnionBlob)
+
 		if whoseCommit.IsLocal() && htlc.sig != nil {
 			h.Signature = htlc.sig.Serialize()
 		}
@@ -653,6 +656,7 @@ func (lc *LightningChannel) diskHtlcToPayDesc(feeRate chainfee.SatPerKWeight,
 		theirPkScript:      theirP2WSH,
 		theirWitnessScript: theirWitnessScript,
 		BlindingPoint:      htlc.BlindingPoint,
+		CustomRecords:      htlc.CustomRecords.Copy(),
 	}, nil
 }
 
@@ -5727,6 +5731,9 @@ func (lc *LightningChannel) htlcAddDescriptor(htlc *lnwire.UpdateAddHTLC,
 		OnionBlob:      htlc.OnionBlob[:],
 		OpenCircuitKey: openKey,
 		BlindingPoint:  htlc.BlindingPoint,
+		// TODO(guggero): Add custom records from HTLC here once we have
+		// the custom records in the HTLC struct (later commits in this
+		// PR).
 	}
 }
 
@@ -5767,7 +5774,9 @@ func (lc *LightningChannel) validateAddHtlc(pd *PaymentDescriptor,
 // ReceiveHTLC adds an HTLC to the state machine's remote update log. This
 // method should be called in response to receiving a new HTLC from the remote
 // party.
-func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.UpdateAddHTLC) (uint64, error) {
+func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.UpdateAddHTLC) (uint64,
+	error) {
+
 	lc.Lock()
 	defer lc.Unlock()
 
@@ -5785,6 +5794,9 @@ func (lc *LightningChannel) ReceiveHTLC(htlc *lnwire.UpdateAddHTLC) (uint64, err
 		HtlcIndex:     lc.remoteUpdateLog.htlcCounter,
 		OnionBlob:     htlc.OnionBlob[:],
 		BlindingPoint: htlc.BlindingPoint,
+		// TODO(guggero): Add custom records from HTLC here once we have
+		// the custom records in the HTLC struct (later commits in this
+		// PR).
 	}
 
 	localACKedIndex := lc.remoteCommitChain.tail().ourMessageIndex

lnwallet/channel_test.go

@@ -2,6 +2,7 @@ package lnwallet
 
 import (
 	"bytes"
+	crand "crypto/rand"
 	"crypto/sha256"
 	"fmt"
 	"math/rand"
@@ -10431,19 +10432,26 @@ func assertPayDescMatchHTLC(t *testing.T, pd PaymentDescriptor,
 // the `Incoming`.
 func createRandomHTLC(t *testing.T, incoming bool) channeldb.HTLC {
 	var onionBlob [lnwire.OnionPacketSize]byte
-	_, err := rand.Read(onionBlob[:])
+	_, err := crand.Read(onionBlob[:])
 	require.NoError(t, err)
 
 	var rHash [lntypes.HashSize]byte
-	_, err = rand.Read(rHash[:])
+	_, err = crand.Read(rHash[:])
 	require.NoError(t, err)
 
 	sig := make([]byte, 64)
-	_, err = rand.Read(sig)
+	_, err = crand.Read(sig)
 	require.NoError(t, err)
 
+	randCustomData := make([]byte, 32)
+	_, err = crand.Read(randCustomData)
+	require.NoError(t, err)
+
+	randCustomType := rand.Intn(255) + lnwire.MinCustomRecordsTlvType
+
 	blinding, err := pubkeyFromHex(
-		"0228f2af0abe322403480fb3ee172f7f1601e67d1da6cad40b54c4468d48236c39", //nolint:lll
+		"0228f2af0abe322403480fb3ee172f7f1601e67d1da6cad40b54c4468d48" +
+			"236c39",
 	)
 	require.NoError(t, err)
 
@@ -10458,9 +10466,13 @@ func createRandomHTLC(t *testing.T, incoming bool) channeldb.HTLC {
 		HtlcIndex:     rand.Uint64(),
 		LogIndex:      rand.Uint64(),
 		BlindingPoint: tlv.SomeRecordT(
-			//nolint:lll
-			tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](blinding),
+			tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
+				blinding,
+			),
 		),
+		CustomRecords: map[uint64][]byte{
+			uint64(randCustomType): randCustomData,
+		},
 	}
 }
 

lnwallet/payment_descriptor.go

@@ -221,4 +221,8 @@ type PaymentDescriptor struct {
 	// blinded route (ie, not the introduction node) from update_add_htlc's
 	// TLVs.
 	BlindingPoint lnwire.BlindingPointRecord
+
+	// CustomRecords also stores the set of optional custom records that
+	// may have been attached to a sent HTLC.
+	CustomRecords lnwire.CustomRecords
 }