lnwire: add new Musig2Nonce TLV record

lnwire/musig2.go

@@ -0,0 +1,50 @@
+package lnwire
+
+import (
+	"io"
+
+	"github.com/btcsuite/btcd/btcec/v2/schnorr/musig2"
+	"github.com/lightningnetwork/lnd/tlv"
+)
+
+const (
+	// NonceRecordType is the TLV type used to encode a local musig2 nonce.
+	NonceRecordType tlv.Type = 4
+)
+
+// Musig2Nonce represents a musig2 public nonce, which is the concatenation of
+// two EC points serialized in compressed format.
+type Musig2Nonce [musig2.PubNonceSize]byte
+
+// Record returns a TLV record that can be used to encode/decode the musig2
+// nonce from a given TLV stream.
+func (m *Musig2Nonce) Record() tlv.Record {
+	return tlv.MakeStaticRecord(
+		NonceRecordType, m, musig2.PubNonceSize, nonceTypeEncoder,
+		nonceTypeDecoder,
+	)
+}
+
+// nonceTypeEncoder is a custom TLV encoder for the Musig2Nonce type.
+func nonceTypeEncoder(w io.Writer, val interface{}, buf *[8]byte) error {
+	if v, ok := val.(*Musig2Nonce); ok {
+		_, err := w.Write(v[:])
+		return err
+	}
+
+	return tlv.NewTypeForEncodingErr(val, "lnwire.Musig2Nonce")
+}
+
+// nonceTypeDecoder is a custom TLV decoder for the Musig2Nonce record.
+func nonceTypeDecoder(r io.Reader, val interface{}, buf *[8]byte,
+	l uint64) error {
+
+	if v, ok := val.(*Musig2Nonce); ok {
+		_, err := io.ReadFull(r, v[:])
+		return err
+	}
+
+	return tlv.NewTypeForDecodingErr(
+		val, "lnwire.Musig2Nonce", l, musig2.PubNonceSize,
+	)
+}