Merge pull request #8660 from GeorgeTsagk/interceptor-wire-records

Enhance `update_add_htlc` with remote peer's custom records

Author: guggero

channeldb/channel.go

@@ -2550,6 +2550,12 @@ 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
@@ -2568,6 +2574,11 @@ 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...)
 }
 
@@ -2589,7 +2600,18 @@ 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.NewCustomRecordsFromTlvTypeMap(tlvMap)
+	if err != nil {
+		return err
 	}
+	h.CustomRecords = customRecords
 
 	return nil
 }

htlcswitch/interceptable_switch.go

@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"sync"
 
+	"github.com/davecgh/go-spew/spew"
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb/models"
@@ -622,15 +623,16 @@ func (f *interceptedForward) Packet() InterceptedPacket {
 			ChanID: f.packet.incomingChanID,
 			HtlcID: f.packet.incomingHTLCID,
 		},
-		OutgoingChanID: f.packet.outgoingChanID,
-		Hash:           f.htlc.PaymentHash,
-		OutgoingExpiry: f.htlc.Expiry,
-		OutgoingAmount: f.htlc.Amount,
-		IncomingAmount: f.packet.incomingAmount,
-		IncomingExpiry: f.packet.incomingTimeout,
-		CustomRecords:  f.packet.customRecords,
-		OnionBlob:      f.htlc.OnionBlob,
-		AutoFailHeight: f.autoFailHeight,
+		OutgoingChanID:            f.packet.outgoingChanID,
+		Hash:                      f.htlc.PaymentHash,
+		OutgoingExpiry:            f.htlc.Expiry,
+		OutgoingAmount:            f.htlc.Amount,
+		IncomingAmount:            f.packet.incomingAmount,
+		IncomingExpiry:            f.packet.incomingTimeout,
+		CustomRecords:             f.packet.customRecords,
+		OnionBlob:                 f.htlc.OnionBlob,
+		AutoFailHeight:            f.autoFailHeight,
+		IncomingWireCustomRecords: f.packet.incomingCustomRecords,
 	}
 }
 
@@ -659,50 +661,58 @@ func (f *interceptedForward) ResumeModified(
 			htlc.Amount = amount
 		})
 
-		//nolint:lll
-		err := fn.MapOptionZ(customRecords, func(records record.CustomSet) error {
-			if len(records) == 0 {
-				return nil
-			}
+		err := fn.MapOptionZ(
+			customRecords, func(records record.CustomSet) error {
+				if len(records) == 0 {
+					return nil
+				}
 
-			// Type cast and validate custom records.
-			htlc.CustomRecords = lnwire.CustomRecords(records)
-			err := htlc.CustomRecords.Validate()
-			if err != nil {
-				return fmt.Errorf("failed to validate custom "+
-					"records: %w", err)
-			}
+				// Type cast and validate custom records.
+				htlc.CustomRecords = lnwire.CustomRecords(
+					records,
+				)
+				err := htlc.CustomRecords.Validate()
+				if err != nil {
+					return fmt.Errorf("failed to validate "+
+						"custom records: %w", err)
+				}
 
-			return nil
-		})
+				return nil
+			},
+		)
 		if err != nil {
 			return fmt.Errorf("failed to encode custom records: %w",
 				err)
 		}
 
 	case *lnwire.UpdateFulfillHTLC:
-		//nolint:lll
-		err := fn.MapOptionZ(customRecords, func(records record.CustomSet) error {
-			if len(records) == 0 {
-				return nil
-			}
+		err := fn.MapOptionZ(
+			customRecords, func(records record.CustomSet) error {
+				if len(records) == 0 {
+					return nil
+				}
 
-			// Type cast and validate custom records.
-			htlc.CustomRecords = lnwire.CustomRecords(records)
-			err := htlc.CustomRecords.Validate()
-			if err != nil {
-				return fmt.Errorf("failed to validate custom "+
-					"records: %w", err)
-			}
+				// Type cast and validate custom records.
+				htlc.CustomRecords = lnwire.CustomRecords(
+					records,
+				)
+				err := htlc.CustomRecords.Validate()
+				if err != nil {
+					return fmt.Errorf("failed to validate "+
+						"custom records: %w", err)
+				}
 
-			return nil
-		})
+				return nil
+			},
+		)
 		if err != nil {
 			return fmt.Errorf("failed to encode custom records: %w",
 				err)
 		}
 	}
 
+	log.Tracef("Forwarding packet %v", spew.Sdump(f.packet))
+
 	// Forward to the switch. A link quit channel isn't needed, because we
 	// are on a different thread now.
 	return f.htlcSwitch.ForwardPackets(nil, f.packet)

htlcswitch/interfaces.go

@@ -357,6 +357,10 @@ type InterceptedPacket struct {
 	// OnionBlob is the onion packet for the next hop
 	OnionBlob [lnwire.OnionPacketSize]byte
 
+	// IncomingWireCustomRecords are user-defined records that were defined
+	// by the peer that forwarded this htlc to us.
+	IncomingWireCustomRecords record.CustomSet
+
 	// AutoFailHeight is the block height at which this intercept will be
 	// failed back automatically.
 	AutoFailHeight int32

htlcswitch/link.go

@@ -29,7 +29,9 @@ import (
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/queue"
+	"github.com/lightningnetwork/lnd/record"
 	"github.com/lightningnetwork/lnd/ticker"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 func init() {
@@ -3354,6 +3356,27 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 				continue
 			}
 
+			var customRecords record.CustomSet
+			err = fn.MapOptionZ(
+				pd.CustomRecords, func(b tlv.Blob) error {
+					r, err := lnwire.ParseCustomRecords(b)
+					if err != nil {
+						return err
+					}
+
+					customRecords = record.CustomSet(r)
+
+					return nil
+				},
+			)
+			if err != nil {
+				l.fail(LinkFailureError{
+					code: ErrInternalError,
+				}, err.Error())
+
+				return
+			}
+
 			switch fwdPkg.State {
 			case channeldb.FwdStateProcessed:
 				// This add was not forwarded on the previous
@@ -3367,7 +3390,7 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 				}
 
 				// Otherwise, it was already processed, we can
-				// can collect it and continue.
+				// collect it and continue.
 				addMsg := &lnwire.UpdateAddHTLC{
 					Expiry:        fwdInfo.OutgoingCTLV,
 					Amount:        fwdInfo.AmountToForward,
@@ -3387,19 +3410,21 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 
 				inboundFee := l.cfg.FwrdingPolicy.InboundFee
 
+				//nolint:lll
 				updatePacket := &htlcPacket{
-					incomingChanID:  l.ShortChanID(),
-					incomingHTLCID:  pd.HtlcIndex,
-					outgoingChanID:  fwdInfo.NextHop,
-					sourceRef:       pd.SourceRef,
-					incomingAmount:  pd.Amount,
-					amount:          addMsg.Amount,
-					htlc:            addMsg,
-					obfuscator:      obfuscator,
-					incomingTimeout: pd.Timeout,
-					outgoingTimeout: fwdInfo.OutgoingCTLV,
-					customRecords:   pld.CustomRecords(),
-					inboundFee:      inboundFee,
+					incomingChanID:        l.ShortChanID(),
+					incomingHTLCID:        pd.HtlcIndex,
+					outgoingChanID:        fwdInfo.NextHop,
+					sourceRef:             pd.SourceRef,
+					incomingAmount:        pd.Amount,
+					amount:                addMsg.Amount,
+					htlc:                  addMsg,
+					obfuscator:            obfuscator,
+					incomingTimeout:       pd.Timeout,
+					outgoingTimeout:       fwdInfo.OutgoingCTLV,
+					customRecords:         pld.CustomRecords(),
+					inboundFee:            inboundFee,
+					incomingCustomRecords: customRecords,
 				}
 				switchPackets = append(
 					switchPackets, updatePacket,
@@ -3455,19 +3480,21 @@ func (l *channelLink) processRemoteAdds(fwdPkg *channeldb.FwdPkg,
 			if fwdPkg.State == channeldb.FwdStateLockedIn {
 				inboundFee := l.cfg.FwrdingPolicy.InboundFee
 
+				//nolint:lll
 				updatePacket := &htlcPacket{
-					incomingChanID:  l.ShortChanID(),
-					incomingHTLCID:  pd.HtlcIndex,
-					outgoingChanID:  fwdInfo.NextHop,
-					sourceRef:       pd.SourceRef,
-					incomingAmount:  pd.Amount,
-					amount:          addMsg.Amount,
-					htlc:            addMsg,
-					obfuscator:      obfuscator,
-					incomingTimeout: pd.Timeout,
-					outgoingTimeout: fwdInfo.OutgoingCTLV,
-					customRecords:   pld.CustomRecords(),
-					inboundFee:      inboundFee,
+					incomingChanID:        l.ShortChanID(),
+					incomingHTLCID:        pd.HtlcIndex,
+					outgoingChanID:        fwdInfo.NextHop,
+					sourceRef:             pd.SourceRef,
+					incomingAmount:        pd.Amount,
+					amount:                addMsg.Amount,
+					htlc:                  addMsg,
+					obfuscator:            obfuscator,
+					incomingTimeout:       pd.Timeout,
+					outgoingTimeout:       fwdInfo.OutgoingCTLV,
+					customRecords:         pld.CustomRecords(),
+					inboundFee:            inboundFee,
+					incomingCustomRecords: customRecords,
 				}
 
 				fwdPkg.FwdFilter.Set(idx)

htlcswitch/packet.go

@@ -98,6 +98,10 @@ type htlcPacket struct {
 	// were included in the payload.
 	customRecords record.CustomSet
 
+	// incomingCustomRecords are custom type range TLVs that are included
+	// in the incoming update_add_htlc.
+	incomingCustomRecords record.CustomSet
+
 	// originalOutgoingChanID is used when sending back failure messages.
 	// It is only used for forwarded Adds on option_scid_alias channels.
 	// This is to avoid possible confusion if a payer uses the public SCID

itest/list_on_test.go

@@ -430,6 +430,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "forward interceptor modified htlc",
 		TestFunc: testForwardInterceptorModifiedHtlc,
 	},
+	{
+		Name:     "forward interceptor wire records",
+		TestFunc: testForwardInterceptorWireRecords,
+	},
 	{
 		Name:     "zero conf channel open",
 		TestFunc: testZeroConfChannelOpen,