Merge pull request #8159 from carlaKC/7298-1-forwardblindedroutes

[1/3]: Preparatory work for Forwarding Blinded Routes

Author: Roasbeef

channeldb/channel.go

@@ -35,6 +35,10 @@ const (
 	// begins to be interpreted as an absolute block height, rather than a
 	// relative one.
 	AbsoluteThawHeightThreshold uint32 = 500000
+
+	// HTLCBlindingPointTLV is the tlv type used for storing blinding
+	// points with HTLCs.
+	HTLCBlindingPointTLV tlv.Type = 0
 )
 
 var (
@@ -2316,7 +2320,56 @@ type HTLC struct {
 	// Note that this extra data is stored inline with the OnionBlob for
 	// legacy reasons, see serialization/deserialization functions for
 	// detail.
-	ExtraData []byte
+	ExtraData lnwire.ExtraOpaqueData
+
+	// BlindingPoint is an optional blinding point included with the HTLC.
+	//
+	// Note: this field is not a part of on-disk representation of the
+	// 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
+}
+
+// serializeExtraData encodes a TLV stream of extra data to be stored with a
+// HTLC. It uses the update_add_htlc TLV types, because this is where extra
+// data is passed with a HTLC. At present blinding points are the only extra
+// data that we will store, and the function is a no-op if a nil blinding
+// point is provided.
+//
+// This function MUST be called to persist all HTLC values when they are
+// serialized.
+func (h *HTLC) serializeExtraData() error {
+	var records []tlv.RecordProducer
+	h.BlindingPoint.WhenSome(func(b tlv.RecordT[lnwire.BlindingPointTlvType,
+		*btcec.PublicKey]) {
+
+		records = append(records, &b)
+	})
+
+	return h.ExtraData.PackRecords(records...)
+}
+
+// deserializeExtraData extracts TLVs from the extra data persisted for the
+// htlc and populates values in the struct accordingly.
+//
+// This function MUST be called to populate the struct properly when HTLCs
+// are deserialized.
+func (h *HTLC) deserializeExtraData() error {
+	if len(h.ExtraData) == 0 {
+		return nil
+	}
+
+	blindingPoint := h.BlindingPoint.Zero()
+	tlvMap, err := h.ExtraData.ExtractRecords(&blindingPoint)
+	if err != nil {
+		return err
+	}
+
+	if val, ok := tlvMap[h.BlindingPoint.TlvType()]; ok && val == nil {
+		h.BlindingPoint = tlv.SomeRecordT(blindingPoint)
+	}
+
+	return nil
 }
 
 // SerializeHtlcs writes out the passed set of HTLC's into the passed writer
@@ -2340,6 +2393,12 @@ func SerializeHtlcs(b io.Writer, htlcs ...HTLC) error {
 	}
 
 	for _, htlc := range htlcs {
+		// Populate TLV stream for any additional fields contained
+		// in the TLV.
+		if err := htlc.serializeExtraData(); err != nil {
+			return err
+		}
+
 		// The onion blob and hltc data are stored as a single var
 		// bytes blob.
 		onionAndExtraData := make(
@@ -2425,6 +2484,12 @@ func DeserializeHtlcs(r io.Reader) ([]HTLC, error) {
 				onionAndExtraData[lnwire.OnionPacketSize:],
 			)
 		}
+
+		// Finally, deserialize any TLVs contained in that extra data
+		// if they are present.
+		if err := htlcs[i].deserializeExtraData(); err != nil {
+			return nil, err
+		}
 	}
 
 	return htlcs, nil
@@ -2440,6 +2505,7 @@ func (h *HTLC) Copy() HTLC {
 	}
 	copy(clone.Signature[:], h.Signature)
 	copy(clone.RHash[:], h.RHash[:])
+	copy(clone.ExtraData, h.ExtraData)
 
 	return clone
 }

channeldb/channel_test.go

@@ -23,6 +23,7 @@ import (
 	"github.com/lightningnetwork/lnd/lntest/channels"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/shachain"
+	"github.com/lightningnetwork/lnd/tlv"
 	"github.com/stretchr/testify/require"
 )
 
@@ -651,8 +652,7 @@ func TestChannelStateTransition(t *testing.T) {
 		{
 			LogIndex: 2,
 			UpdateMsg: &lnwire.UpdateAddHTLC{
-				ChanID:    lnwire.ChannelID{1, 2, 3},
-				ExtraData: make([]byte, 0),
+				ChanID: lnwire.ChannelID{1, 2, 3},
 			},
 		},
 	}
@@ -710,25 +710,22 @@ func TestChannelStateTransition(t *testing.T) {
 				wireSig,
 				wireSig,
 			},
-			ExtraData: make([]byte, 0),
 		},
 		LogUpdates: []LogUpdate{
 			{
 				LogIndex: 1,
 				UpdateMsg: &lnwire.UpdateAddHTLC{
-					ID:        1,
-					Amount:    lnwire.NewMSatFromSatoshis(100),
-					Expiry:    25,
-					ExtraData: make([]byte, 0),
+					ID:     1,
+					Amount: lnwire.NewMSatFromSatoshis(100),
+					Expiry: 25,
 				},
 			},
 			{
 				LogIndex: 2,
 				UpdateMsg: &lnwire.UpdateAddHTLC{
-					ID:        2,
-					Amount:    lnwire.NewMSatFromSatoshis(200),
-					Expiry:    50,
-					ExtraData: make([]byte, 0),
+					ID:     2,
+					Amount: lnwire.NewMSatFromSatoshis(200),
+					Expiry: 50,
 				},
 			},
 		},
@@ -1610,9 +1607,25 @@ func TestHTLCsExtraData(t *testing.T) {
 		OnionBlob:     lnmock.MockOnion(),
 	}
 
+	// Add a blinding point to a htlc.
+	blindingPointHTLC := HTLC{
+		Signature:     testSig.Serialize(),
+		Incoming:      false,
+		Amt:           10,
+		RHash:         key,
+		RefundTimeout: 1,
+		OnionBlob:     lnmock.MockOnion(),
+		BlindingPoint: tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[lnwire.BlindingPointTlvType](
+				pubKey,
+			),
+		),
+	}
+
 	testCases := []struct {
-		name  string
-		htlcs []HTLC
+		name        string
+		htlcs       []HTLC
+		blindingIdx int
 	}{
 		{
 			// Serialize multiple HLTCs with no extra data to
@@ -1624,30 +1637,12 @@ func TestHTLCsExtraData(t *testing.T) {
 			},
 		},
 		{
+			// Some HTLCs with extra data, some without.
 			name: "mixed extra data",
 			htlcs: []HTLC{
 				mockHtlc,
-				{
-					Signature:     testSig.Serialize(),
-					Incoming:      false,
-					Amt:           10,
-					RHash:         key,
-					RefundTimeout: 1,
-					OnionBlob:     lnmock.MockOnion(),
-					ExtraData:     []byte{1, 2, 3},
-				},
+				blindingPointHTLC,
 				mockHtlc,
-				{
-					Signature:     testSig.Serialize(),
-					Incoming:      false,
-					Amt:           10,
-					RHash:         key,
-					RefundTimeout: 1,
-					OnionBlob:     lnmock.MockOnion(),
-					ExtraData: bytes.Repeat(
-						[]byte{9}, 999,
-					),
-				},
 			},
 		},
 	}
@@ -1665,7 +1660,15 @@ func TestHTLCsExtraData(t *testing.T) {
 			r := bytes.NewReader(b.Bytes())
 			htlcs, err := DeserializeHtlcs(r)
 			require.NoError(t, err)
-			require.Equal(t, testCase.htlcs, htlcs)
+
+			require.EqualValues(t, len(testCase.htlcs), len(htlcs))
+			for i, htlc := range htlcs {
+				// We use the extra data field when we
+				// serialize, so we set to nil to be able to
+				// assert on equal for the test.
+				htlc.ExtraData = nil
+				require.Equal(t, testCase.htlcs[i], htlc)
+			}
 		})
 	}
 }

cmd/lncli/cmd_payments.go

@@ -1250,9 +1250,9 @@ func parseBlindedPaymentParameters(ctx *cli.Context) (
 		BaseFeeMsat: ctx.Uint64(
 			blindedBaseFlag.Name,
 		),
-		ProportionalFeeMsat: ctx.Uint64(
+		ProportionalFeeRate: uint32(ctx.Uint64(
 			blindedPPMFlag.Name,
-		),
+		)),
 		TotalCltvDelta: uint32(ctx.Uint64(
 			blindedCLTVFlag.Name,
 		)),

contractcourt/htlc_incoming_contest_resolver.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 
+	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -17,6 +18,7 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/queue"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 // htlcIncomingContestResolver is a ContractResolver that's able to resolve an
@@ -520,9 +522,18 @@ func (h *htlcIncomingContestResolver) Supplement(htlc channeldb.HTLC) {
 func (h *htlcIncomingContestResolver) decodePayload() (*hop.Payload,
 	[]byte, error) {
 
+	var blindingPoint *btcec.PublicKey
+	h.htlc.BlindingPoint.WhenSome(
+		func(b tlv.RecordT[lnwire.BlindingPointTlvType,
+			*btcec.PublicKey]) {
+
+			blindingPoint = b.Val
+		},
+	)
+
 	onionReader := bytes.NewReader(h.htlc.OnionBlob[:])
 	iterator, err := h.OnionProcessor.ReconstructHopIterator(
-		onionReader, h.htlc.RHash[:],
+		onionReader, h.htlc.RHash[:], blindingPoint,
 	)
 	if err != nil {
 		return nil, nil, err

contractcourt/htlc_incoming_contest_resolver_test.go

@@ -6,6 +6,7 @@ import (
 	"io/ioutil"
 	"testing"
 
+	"github.com/btcsuite/btcd/btcec/v2"
 	sphinx "github.com/lightningnetwork/lightning-onion"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -288,8 +289,8 @@ type mockOnionProcessor struct {
 	offeredOnionBlob []byte
 }
 
-func (o *mockOnionProcessor) ReconstructHopIterator(r io.Reader, rHash []byte) (
-	hop.Iterator, error) {
+func (o *mockOnionProcessor) ReconstructHopIterator(r io.Reader, rHash []byte,
+	blindingPoint *btcec.PublicKey) (hop.Iterator, error) {
 
 	data, err := ioutil.ReadAll(r)
 	if err != nil {

contractcourt/interfaces.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"io"
 
+	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
@@ -40,7 +41,8 @@ type Registry interface {
 type OnionProcessor interface {
 	// ReconstructHopIterator attempts to decode a valid sphinx packet from
 	// the passed io.Reader instance.
-	ReconstructHopIterator(r io.Reader, rHash []byte) (hop.Iterator, error)
+	ReconstructHopIterator(r io.Reader, rHash []byte,
+		blindingKey *btcec.PublicKey) (hop.Iterator, error)
 }
 
 // UtxoSweeper defines the sweep functions that contract court requires.

docs/release-notes/release-notes-0.18.0.md

@@ -172,6 +172,9 @@
 * When computing a minimum fee for transaction construction, `lnd` [now takes our
 bitcoin peers' feefilter values into account](https://github.com/lightningnetwork/lnd/pull/8418).
 
+* [Preparatory work](https://github.com/lightningnetwork/lnd/pull/8159) for 
+  forwarding of blinded routes was added.
+
 ## RPC Additions
 
 * [Deprecated](https://github.com/lightningnetwork/lnd/pull/7175)