[2/?]: lnwallet+channeldb: add new AuxLeafStore for dynamic aux leaves

chainreg/chainregistry.go

@@ -24,6 +24,7 @@ import (
 	"github.com/lightningnetwork/lnd/chainntnfs/neutrinonotify"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/kvdb"
@@ -63,6 +64,10 @@ type Config struct {
 	// state.
 	ChanStateDB *channeldb.ChannelStateDB
 
+	// AuxLeafStore is an optional store that can be used to store auxiliary
+	// leaves for certain custom channel types.
+	AuxLeafStore fn.Option[lnwallet.AuxLeafStore]
+
 	// BlockCache is the main cache for storing block information.
 	BlockCache *blockcache.BlockCache
 

channeldb/channel.go

@@ -251,6 +251,10 @@ type chanAuxData struct {
 	// tapscriptRoot is the optional Tapscript root the channel funding
 	// output commits to.
 	tapscriptRoot tlv.OptionalRecordT[tlv.TlvType6, [32]byte]
+
+	// customBlob is an optional TLV encoded blob of data representing
+	// custom channel funding information.
+	customBlob tlv.OptionalRecordT[tlv.TlvType7, tlv.Blob]
 }
 
 // encode serializes the chanAuxData to the given io.Writer.
@@ -269,6 +273,9 @@ func (c *chanAuxData) encode(w io.Writer) error {
 			tlvRecords = append(tlvRecords, root.Record())
 		},
 	)
+	c.customBlob.WhenSome(func(blob tlv.RecordT[tlv.TlvType7, tlv.Blob]) {
+		tlvRecords = append(tlvRecords, blob.Record())
+	})
 
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(tlvRecords...)
@@ -283,6 +290,7 @@ func (c *chanAuxData) encode(w io.Writer) error {
 func (c *chanAuxData) decode(r io.Reader) error {
 	memo := c.memo.Zero()
 	tapscriptRoot := c.tapscriptRoot.Zero()
+	blob := c.customBlob.Zero()
 
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(
@@ -292,6 +300,7 @@ func (c *chanAuxData) decode(r io.Reader) error {
 		c.realScid.Record(),
 		memo.Record(),
 		tapscriptRoot.Record(),
+		blob.Record(),
 	)
 	if err != nil {
 		return err
@@ -308,6 +317,9 @@ func (c *chanAuxData) decode(r io.Reader) error {
 	if _, ok := tlvs[tapscriptRoot.TlvType()]; ok {
 		c.tapscriptRoot = tlv.SomeRecordT(tapscriptRoot)
 	}
+	if _, ok := tlvs[c.customBlob.TlvType()]; ok {
+		c.customBlob = tlv.SomeRecordT(blob)
+	}
 
 	return nil
 }
@@ -325,6 +337,9 @@ func (c *chanAuxData) toOpenChan(o *OpenChannel) {
 	c.tapscriptRoot.WhenSomeV(func(h [32]byte) {
 		o.TapscriptRoot = fn.Some[chainhash.Hash](h)
 	})
+	c.customBlob.WhenSomeV(func(blob tlv.Blob) {
+		o.CustomBlob = fn.Some(blob)
+	})
 }
 
 // newChanAuxDataFromChan creates a new chanAuxData from the given channel.
@@ -354,6 +369,11 @@ func newChanAuxDataFromChan(openChan *OpenChannel) *chanAuxData {
 			tlv.NewPrimitiveRecord[tlv.TlvType6, [32]byte](h),
 		)
 	})
+	openChan.CustomBlob.WhenSome(func(blob tlv.Blob) {
+		c.customBlob = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType7](blob),
+		)
+	})
 
 	return c
 }
@@ -607,6 +627,74 @@ type ChannelConfig struct {
 	HtlcBasePoint keychain.KeyDescriptor
 }
 
+// commitAuxData stores all the optional data that may be stored as a TLV stream
+// at the _end_ of the normal serialized commit on disk.
+type commitAuxData struct {
+	// customBlob is a custom blob that may store extra data for custom
+	// channels.
+	customBlob tlv.OptionalRecordT[tlv.TlvType1, tlv.Blob]
+}
+
+// encode encodes the aux data into the passed io.Writer.
+func (c *commitAuxData) encode(w io.Writer) error {
+	var tlvRecords []tlv.Record
+	c.customBlob.WhenSome(func(blob tlv.RecordT[tlv.TlvType1, tlv.Blob]) {
+		tlvRecords = append(tlvRecords, blob.Record())
+	})
+
+	// Create the tlv stream.
+	tlvStream, err := tlv.NewStream(tlvRecords...)
+	if err != nil {
+		return err
+	}
+
+	return tlvStream.Encode(w)
+}
+
+// decode attempts to ecode the aux data from the passed io.Reader.
+func (c *commitAuxData) decode(r io.Reader) error {
+	blob := c.customBlob.Zero()
+
+	tlvStream, err := tlv.NewStream(
+		blob.Record(),
+	)
+	if err != nil {
+		return err
+	}
+
+	tlvs, err := tlvStream.DecodeWithParsedTypes(r)
+	if err != nil {
+		return err
+	}
+
+	if _, ok := tlvs[c.customBlob.TlvType()]; ok {
+		c.customBlob = tlv.SomeRecordT(blob)
+	}
+
+	return nil
+}
+
+// toChanCommit extracts the optional data stored in the commitAuxData struct
+// and stores it in the ChannelCommitment.
+func (c *commitAuxData) toChanCommit(commit *ChannelCommitment) {
+	c.customBlob.WhenSomeV(func(blob tlv.Blob) {
+		commit.CustomBlob = fn.Some(blob)
+	})
+}
+
+// newCommitAuxData creates an aux data struct from the normal chan commitment.
+func newCommitAuxData(commit *ChannelCommitment) commitAuxData {
+	var c commitAuxData
+
+	commit.CustomBlob.WhenSome(func(blob tlv.Blob) {
+		c.customBlob = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType1](blob),
+		)
+	})
+
+	return c
+}
+
 // ChannelCommitment is a snapshot of the commitment state at a particular
 // point in the commitment chain. With each state transition, a snapshot of the
 // current state along with all non-settled HTLCs are recorded. These snapshots
@@ -673,6 +761,11 @@ type ChannelCommitment struct {
 	// able by us.
 	CommitTx *wire.MsgTx
 
+	// CustomBlob is an optional blob that can be used to store information
+	// specific to a custom channel type. This may track some custom
+	// specific state for this given commitment.
+	CustomBlob fn.Option[tlv.Blob]
+
 	// CommitSig is one half of the signature required to fully complete
 	// the script for the commitment transaction above. This is the
 	// signature signed by the remote party for our version of the
@@ -682,9 +775,6 @@ type ChannelCommitment struct {
 	// Htlcs is the set of HTLC's that are pending at this particular
 	// commitment height.
 	Htlcs []HTLC
-
-	// TODO(roasbeef): pending commit pointer?
-	//  * lets just walk through
 }
 
 // ChannelStatus is a bit vector used to indicate whether an OpenChannel is in
@@ -982,6 +1072,12 @@ type OpenChannel struct {
 	// funding output.
 	TapscriptRoot fn.Option[chainhash.Hash]
 
+	// CustomBlob is an optional blob that can be used to store information
+	// specific to a custom channel type. This information is only created
+	// at channel funding time, and after wards is to be considered
+	// immutable.
+	CustomBlob fn.Option[tlv.Blob]
+
 	// TODO(roasbeef): eww
 	Db *ChannelStateDB
 
@@ -2793,6 +2889,16 @@ func serializeCommitDiff(w io.Writer, diff *CommitDiff) error { // nolint: dupl
 		}
 	}
 
+	// We'll also encode the commit aux data stream here. We do this here
+	// rather than above (at the call to serializeChanCommit), to ensure
+	// backwards compat for reads to existing non-custom channels.
+	//
+	// TODO(roasbeef): migrate it after all?
+	auxData := newCommitAuxData(&diff.Commitment)
+	if err := auxData.encode(w); err != nil {
+		return fmt.Errorf("unable to write aux data: %w", err)
+	}
+
 	return nil
 }
 
@@ -2853,6 +2959,17 @@ func deserializeCommitDiff(r io.Reader) (*CommitDiff, error) {
 		}
 	}
 
+	// As a final step, we'll read out any aux commit data that we have at
+	// the end of this byte stream. We do this here to ensure backward
+	// compatibility, as otherwise we risk erroneously reading into the
+	// wrong field.
+	var auxData commitAuxData
+	if err := auxData.decode(r); err != nil {
+		return nil, fmt.Errorf("unable to decode aux data: %w", err)
+	}
+
+	auxData.toChanCommit(&d.Commitment)
+
 	return &d, nil
 }
 
@@ -3831,6 +3948,13 @@ func (c *OpenChannel) Snapshot() *ChannelSnapshot {
 		},
 	}
 
+	localCommit.CustomBlob.WhenSome(func(blob tlv.Blob) {
+		blobCopy := make([]byte, len(blob))
+		copy(blobCopy, blob)
+
+		snapshot.ChannelCommitment.CustomBlob = fn.Some(blobCopy)
+	})
+
 	// Copy over the current set of HTLCs to ensure the caller can't mutate
 	// our internal state.
 	snapshot.Htlcs = make([]HTLC, len(localCommit.Htlcs))
@@ -4222,6 +4346,12 @@ func putChanCommitment(chanBucket kvdb.RwBucket, c *ChannelCommitment,
 		return err
 	}
 
+	// Before we write to disk, we'll also write our aux data as well.
+	auxData := newCommitAuxData(c)
+	if err := auxData.encode(&b); err != nil {
+		return fmt.Errorf("unable to write aux data: %w", err)
+	}
+
 	return chanBucket.Put(commitKey, b.Bytes())
 }
 
@@ -4367,7 +4497,9 @@ func deserializeChanCommit(r io.Reader) (ChannelCommitment, error) {
 	return c, nil
 }
 
-func fetchChanCommitment(chanBucket kvdb.RBucket, local bool) (ChannelCommitment, error) {
+func fetchChanCommitment(chanBucket kvdb.RBucket,
+	local bool) (ChannelCommitment, error) {
+
 	var commitKey []byte
 	if local {
 		commitKey = append(chanCommitmentKey, byte(0x00))
@@ -4381,7 +4513,23 @@ func fetchChanCommitment(chanBucket kvdb.RBucket, local bool) (ChannelCommitment
 	}
 
 	r := bytes.NewReader(commitBytes)
-	return deserializeChanCommit(r)
+	chanCommit, err := deserializeChanCommit(r)
+	if err != nil {
+		return ChannelCommitment{}, fmt.Errorf("unable to decode "+
+			"chan commit: %w", err)
+	}
+
+	// We'll also check to see if we have any aux data stored as the end of
+	// the stream.
+	var auxData commitAuxData
+	if err := auxData.decode(r); err != nil {
+		return ChannelCommitment{}, fmt.Errorf("unable to decode "+
+			"chan aux data: %w", err)
+	}
+
+	auxData.toChanCommit(&chanCommit)
+
+	return chanCommit, nil
 }
 
 func fetchChanCommitments(chanBucket kvdb.RBucket, channel *OpenChannel) error {