channeldb: add custom blobs to RevocationLog+HTLCEntry

This'll be useful for custom channel types that want to store extra information that'll be useful to help handle channel revocation cases.

channeldb/revocation_log.go

@@ -164,22 +164,32 @@ type HTLCEntry struct {
 	//
 	// NOTE: this field is the memory representation of the field amtUint.
 	Amt tlv.RecordT[tlv.TlvType4, tlv.BigSizeT[btcutil.Amount]]
+
+	// CustomBlob is an optional blob that can be used to store information
+	// specific to revocation handling for a custom channel type.
+	CustomBlob tlv.OptionalRecordT[tlv.TlvType5, tlv.Blob]
 }
 
 // toTlvStream converts an HTLCEntry record into a tlv representation.
 func (h *HTLCEntry) toTlvStream() (*tlv.Stream, error) {
-	return tlv.NewStream(
+	records := []tlv.Record{
 		h.RHash.Record(),
 		h.RefundTimeout.Record(),
 		h.OutputIndex.Record(),
 		h.Incoming.Record(),
 		h.Amt.Record(),
-	)
+	}
+
+	h.CustomBlob.WhenSome(func(r tlv.RecordT[tlv.TlvType5, tlv.Blob]) {
+		records = append(records, r.Record())
+	})
+
+	return tlv.NewStream(records...)
 }
 
 // NewHTLCEntryFromHTLC creates a new HTLCEntry from an HTLC.
-func NewHTLCEntryFromHTLC(htlc HTLC) *HTLCEntry {
-	return &HTLCEntry{
+func NewHTLCEntryFromHTLC(htlc HTLC) (*HTLCEntry, error) {
+	h := &HTLCEntry{
 		RHash: tlv.NewRecordT[tlv.TlvType0](
 			NewSparsePayHash(htlc.RHash),
 		),
@@ -194,6 +204,19 @@ func NewHTLCEntryFromHTLC(htlc HTLC) *HTLCEntry {
 			tlv.NewBigSizeT(htlc.Amt.ToSatoshis()),
 		),
 	}
+
+	if len(htlc.CustomRecords) != 0 {
+		blob, err := htlc.CustomRecords.Serialize()
+		if err != nil {
+			return nil, err
+		}
+
+		h.CustomBlob = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType5, tlv.Blob](blob),
+		)
+	}
+
+	return h, nil
 }
 
 // RevocationLog stores the info needed to construct a breach retribution. Its
@@ -236,13 +259,19 @@ type RevocationLog struct {
 	// this field, it could be the case that the field is not present for
 	// all revocation logs.
 	TheirBalance tlv.OptionalRecordT[tlv.TlvType4, BigSizeMilliSatoshi]
+
+	// 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 tlv.OptionalRecordT[tlv.TlvType5, tlv.Blob]
 }
 
 // NewRevocationLog creates a new RevocationLog from the given parameters.
 func NewRevocationLog(ourOutputIndex uint16, theirOutputIndex uint16,
 	commitHash [32]byte, ourBalance,
-	theirBalance fn.Option[lnwire.MilliSatoshi],
-	htlcs []*HTLCEntry) RevocationLog {
+	theirBalance fn.Option[lnwire.MilliSatoshi], htlcs []*HTLCEntry,
+	customBlob fn.Option[tlv.Blob]) RevocationLog {
 
 	rl := RevocationLog{
 		OurOutputIndex: tlv.NewPrimitiveRecord[tlv.TlvType0](
@@ -267,6 +296,12 @@ func NewRevocationLog(ourOutputIndex uint16, theirOutputIndex uint16,
 		))
 	})
 
+	customBlob.WhenSome(func(blob tlv.Blob) {
+		rl.CustomBlob = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType5, tlv.Blob](blob),
+		)
+	})
+
 	return rl
 }
 
@@ -298,6 +333,12 @@ func putRevocationLog(bucket kvdb.RwBucket, commit *ChannelCommitment,
 		HTLCEntries: make([]*HTLCEntry, 0, len(commit.Htlcs)),
 	}
 
+	commit.CustomBlob.WhenSome(func(blob tlv.Blob) {
+		rl.CustomBlob = tlv.SomeRecordT(
+			tlv.NewPrimitiveRecord[tlv.TlvType5, tlv.Blob](blob),
+		)
+	})
+
 	if !noAmtData {
 		rl.OurBalance = tlv.SomeRecordT(tlv.NewRecordT[tlv.TlvType3](
 			tlv.NewBigSizeT(commit.LocalBalance),
@@ -320,7 +361,10 @@ func putRevocationLog(bucket kvdb.RwBucket, commit *ChannelCommitment,
 			return ErrOutputIndexTooBig
 		}
 
-		entry := NewHTLCEntryFromHTLC(htlc)
+		entry, err := NewHTLCEntryFromHTLC(htlc)
+		if err != nil {
+			return err
+		}
 		rl.HTLCEntries = append(rl.HTLCEntries, entry)
 	}
 
@@ -373,6 +417,10 @@ func serializeRevocationLog(w io.Writer, rl *RevocationLog) error {
 		},
 	)
 
+	rl.CustomBlob.WhenSome(func(r tlv.RecordT[tlv.TlvType5, tlv.Blob]) {
+		records = append(records, r.Record())
+	})
+
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(records...)
 	if err != nil {
@@ -413,6 +461,7 @@ func deserializeRevocationLog(r io.Reader) (RevocationLog, error) {
 
 	ourBalance := rl.OurBalance.Zero()
 	theirBalance := rl.TheirBalance.Zero()
+	customBlob := rl.CustomBlob.Zero()
 
 	// Create the tlv stream.
 	tlvStream, err := tlv.NewStream(
@@ -421,6 +470,7 @@ func deserializeRevocationLog(r io.Reader) (RevocationLog, error) {
 		rl.CommitTxHash.Record(),
 		ourBalance.Record(),
 		theirBalance.Record(),
+		customBlob.Record(),
 	)
 	if err != nil {
 		return rl, err
@@ -440,6 +490,10 @@ func deserializeRevocationLog(r io.Reader) (RevocationLog, error) {
 		rl.TheirBalance = tlv.SomeRecordT(theirBalance)
 	}
 
+	if t, ok := parsedTypes[customBlob.TlvType()]; ok && t == nil {
+		rl.CustomBlob = tlv.SomeRecordT(customBlob)
+	}
+
 	// Read the HTLC entries.
 	rl.HTLCEntries, err = deserializeHTLCEntries(r)
 
@@ -454,14 +508,26 @@ func deserializeHTLCEntries(r io.Reader) ([]*HTLCEntry, error) {
 	for {
 		var htlc HTLCEntry
 
+		customBlob := htlc.CustomBlob.Zero()
+
 		// Create the tlv stream.
-		tlvStream, err := htlc.toTlvStream()
+		records := []tlv.Record{
+			htlc.RHash.Record(),
+			htlc.RefundTimeout.Record(),
+			htlc.OutputIndex.Record(),
+			htlc.Incoming.Record(),
+			htlc.Amt.Record(),
+			customBlob.Record(),
+		}
+
+		tlvStream, err := tlv.NewStream(records...)
 		if err != nil {
 			return nil, err
 		}
 
 		// Read the HTLC entry.
-		if _, err := readTlvStream(r, tlvStream); err != nil {
+		parsedTypes, err := readTlvStream(r, tlvStream)
+		if err != nil {
 			// We've reached the end when hitting an EOF.
 			if err == io.ErrUnexpectedEOF {
 				break
@@ -469,6 +535,10 @@ func deserializeHTLCEntries(r io.Reader) ([]*HTLCEntry, error) {
 			return nil, err
 		}
 
+		if t, ok := parsedTypes[customBlob.TlvType()]; ok && t == nil {
+			htlc.CustomBlob = tlv.SomeRecordT(customBlob)
+		}
+
 		// Append the entry.
 		htlcs = append(htlcs, &htlc)
 	}