lnwire: add PartialSig to FundingCreated

lnwire/funding_created.go

@@ -5,6 +5,7 @@ import (
 	"io"
 
 	"github.com/btcsuite/btcd/wire"
+	"github.com/lightningnetwork/lnd/tlv"
 )
 
 // FundingCreated is sent from Alice (the initiator) to Bob (the responder),
@@ -26,6 +27,13 @@ type FundingCreated struct {
 	// transaction.
 	CommitSig Sig
 
+	// PartialSig is used to transmit a musig2 extended partial signature
+	// that also carries along the public nonce of the signer.
+	//
+	// NOTE: This field is only populated if a musig2 taproot channel is
+	// being signed for. In this case, the above Sig type MUST be blank.
+	PartialSig *PartialSigWithNonce
+
 	// ExtraData is the set of data that was appended to this message to
 	// fill out the full maximum transport message size. These fields can
 	// be used to specify optional data such as custom TLV fields.
@@ -42,6 +50,15 @@ var _ Message = (*FundingCreated)(nil)
 //
 // This is part of the lnwire.Message interface.
 func (f *FundingCreated) Encode(w *bytes.Buffer, pver uint32) error {
+	recordProducers := make([]tlv.RecordProducer, 0, 1)
+	if f.PartialSig != nil {
+		recordProducers = append(recordProducers, f.PartialSig)
+	}
+	err := EncodeMessageExtraData(&f.ExtraData, recordProducers...)
+	if err != nil {
+		return err
+	}
+
 	if err := WriteBytes(w, f.PendingChannelID[:]); err != nil {
 		return err
 	}
@@ -63,10 +80,36 @@ func (f *FundingCreated) Encode(w *bytes.Buffer, pver uint32) error {
 //
 // This is part of the lnwire.Message interface.
 func (f *FundingCreated) Decode(r io.Reader, pver uint32) error {
-	return ReadElements(
+	err := ReadElements(
 		r, f.PendingChannelID[:], &f.FundingPoint, &f.CommitSig,
-		&f.ExtraData,
 	)
+	if err != nil {
+		return err
+	}
+
+	var tlvRecords ExtraOpaqueData
+	if err := ReadElements(r, &tlvRecords); err != nil {
+		return err
+	}
+
+	var (
+		partialSig PartialSigWithNonce
+	)
+	typeMap, err := tlvRecords.ExtractRecords(&partialSig)
+	if err != nil {
+		return err
+	}
+
+	// Set the corresponding TLV types if they were included in the stream.
+	if val, ok := typeMap[PartialSigWithNonceRecordType]; ok && val == nil {
+		f.PartialSig = &partialSig
+	}
+
+	if len(tlvRecords) != 0 {
+		f.ExtraData = tlvRecords
+	}
+
+	return nil
 }
 
 // MsgType returns the uint32 code which uniquely identifies this message as a