channeldb: add optional TapscriptRoot field + feature bit

Author: Roasbeef

channeldb/channel.go

@@ -247,6 +247,10 @@ type chanAuxData struct {
 	// memo is an optional text field that gives context to the user about
 	// the channel.
 	memo tlv.OptionalRecordT[tlv.TlvType5, []byte]
+
+	// tapscriptRoot is the optional Tapscript root the channel funding
+	// output commits to.
+	tapscriptRoot tlv.OptionalRecordT[tlv.TlvType6, [32]byte]
 }
 
 // encode serializes the chanAuxData to the given io.Writer.
@@ -260,6 +264,11 @@ func (c *chanAuxData) encode(w io.Writer) error {
 	c.memo.WhenSome(func(memo tlv.RecordT[tlv.TlvType5, []byte]) {
 		tlvRecords = append(tlvRecords, memo.Record())
 	})
+	c.tapscriptRoot.WhenSome(
+		func(root tlv.RecordT[tlv.TlvType6, [32]byte]) {
+			tlvRecords = append(tlvRecords, root.Record())
+		},
+	)
 
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(tlvRecords...)
@@ -273,6 +282,7 @@ func (c *chanAuxData) encode(w io.Writer) error {
 // decode deserializes the chanAuxData from the given io.Reader.
 func (c *chanAuxData) decode(r io.Reader) error {
 	memo := c.memo.Zero()
+	tapscriptRoot := c.tapscriptRoot.Zero()
 
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(
@@ -281,6 +291,7 @@ func (c *chanAuxData) decode(r io.Reader) error {
 		c.initialRemoteBalance.Record(),
 		c.realScid.Record(),
 		memo.Record(),
+		tapscriptRoot.Record(),
 	)
 	if err != nil {
 		return err
@@ -294,6 +305,9 @@ func (c *chanAuxData) decode(r io.Reader) error {
 	if _, ok := tlvs[memo.TlvType()]; ok {
 		c.memo = tlv.SomeRecordT(memo)
 	}
+	if _, ok := tlvs[tapscriptRoot.TlvType()]; ok {
+		c.tapscriptRoot = tlv.SomeRecordT(tapscriptRoot)
+	}
 
 	return nil
 }
@@ -308,6 +322,9 @@ func (c *chanAuxData) toOpenChan(o *OpenChannel) {
 	c.memo.WhenSomeV(func(memo []byte) {
 		o.Memo = memo
 	})
+	c.tapscriptRoot.WhenSomeV(func(h [32]byte) {
+		o.TapscriptRoot = fn.Some[chainhash.Hash](h)
+	})
 }
 
 // newChanAuxDataFromChan creates a new chanAuxData from the given channel.
@@ -332,6 +349,11 @@ func newChanAuxDataFromChan(openChan *OpenChannel) *chanAuxData {
 			tlv.NewPrimitiveRecord[tlv.TlvType5](openChan.Memo),
 		)
 	}
+	openChan.TapscriptRoot.WhenSome(func(h chainhash.Hash) {
+		c.tapscriptRoot = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType6, [32]byte](h),
+		)
+	})
 
 	return c
 }
@@ -413,6 +435,11 @@ const (
 	// SimpleTaprootFeatureBit indicates that the simple-taproot-chans
 	// feature bit was negotiated during the lifetime of the channel.
 	SimpleTaprootFeatureBit ChannelType = 1 << 10
+
+	// TapscriptRootBit indicates that this is a MuSig2 channel with a top
+	// level tapscript commitment. This MUST be set along with the
+	// SimpleTaprootFeatureBit.
+	TapscriptRootBit ChannelType = 1 << 11
 )
 
 // IsSingleFunder returns true if the channel type if one of the known single
@@ -483,6 +510,12 @@ func (c ChannelType) IsTaproot() bool {
 	return c&SimpleTaprootFeatureBit == SimpleTaprootFeatureBit
 }
 
+// HasTapscriptRoot returns true if the channel is using a top level tapscript
+// root commitment.
+func (c ChannelType) HasTapscriptRoot() bool {
+	return c&TapscriptRootBit == TapscriptRootBit
+}
+
 // ChannelConstraints represents a set of constraints meant to allow a node to
 // limit their exposure, enact flow control and ensure that all HTLCs are
 // economically relevant. This struct will be mirrored for both sides of the

channeldb/channel_test.go

@@ -17,6 +17,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/channeldb/models"
 	"github.com/lightningnetwork/lnd/clock"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnmock"
@@ -172,7 +173,7 @@ func fundingPointOption(chanPoint wire.OutPoint) testChannelOption {
 }
 
 // channelIDOption is an option which sets the short channel ID of the channel.
-var channelIDOption = func(chanID lnwire.ShortChannelID) testChannelOption {
+func channelIDOption(chanID lnwire.ShortChannelID) testChannelOption {
 	return func(params *testChannelParams) {
 		params.channel.ShortChannelID = chanID
 	}
@@ -312,6 +313,9 @@ func createTestChannelState(t *testing.T, cdb *ChannelStateDB) *OpenChannel {
 	uniqueOutputIndex.Add(1)
 	op := wire.OutPoint{Hash: key, Index: uniqueOutputIndex.Load()}
 
+	var tapscriptRoot chainhash.Hash
+	copy(tapscriptRoot[:], bytes.Repeat([]byte{1}, 32))
+
 	return &OpenChannel{
 		ChanType:          SingleFunderBit | FrozenBit,
 		ChainHash:         key,
@@ -354,6 +358,8 @@ func createTestChannelState(t *testing.T, cdb *ChannelStateDB) *OpenChannel {
 		ThawHeight:              uint32(defaultPendingHeight),
 		InitialLocalBalance:     lnwire.MilliSatoshi(9000),
 		InitialRemoteBalance:    lnwire.MilliSatoshi(3000),
+		Memo:                    []byte("test"),
+		TapscriptRoot:           fn.Some(tapscriptRoot),
 	}
 }