lnwire: add AnnounceSignatures2 message

And ensure that it implements the AnnounceSignatures interface.

lnwire/announcement_signatures_2.go

@@ -0,0 +1,97 @@
+package lnwire
+
+import (
+	"bytes"
+	"io"
+)
+
+// AnnounceSignatures2 is a direct message between two endpoints of a
+// channel and serves as an opt-in mechanism to allow the announcement of
+// a taproot channel to the rest of the network. It contains the necessary
+// signatures by the sender to construct the channel_announcement_2 message.
+type AnnounceSignatures2 struct {
+	// ChannelID is the unique description of the funding transaction.
+	// Channel id is better for users and debugging and short channel id is
+	// used for quick test on existence of the particular utxo inside the
+	// blockchain, because it contains information about block.
+	ChannelID ChannelID
+
+	// ShortChannelID is the unique description of the funding transaction.
+	// It is constructed with the most significant 3 bytes as the block
+	// height, the next 3 bytes indicating the transaction index within the
+	// block, and the least significant two bytes indicating the output
+	// index which pays to the channel.
+	ShortChannelID ShortChannelID
+
+	// PartialSignature is the combination of the partial Schnorr signature
+	// created for the node's bitcoin key with the partial signature created
+	// for the node's node ID key.
+	PartialSignature PartialSig
+
+	// ExtraOpaqueData is the set of data that was appended to this
+	// message, some of which we may not actually know how to iterate or
+	// parse. By holding onto this data, we ensure that we're able to
+	// properly validate the set of signatures that cover these new fields,
+	// and ensure we're able to make upgrades to the network in a forwards
+	// compatible manner.
+	ExtraOpaqueData ExtraOpaqueData
+}
+
+// A compile time check to ensure AnnounceSignatures2 implements the
+// lnwire.Message interface.
+var _ Message = (*AnnounceSignatures2)(nil)
+
+// Decode deserializes a serialized AnnounceSignatures2 stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the lnwire.Message interface.
+func (a *AnnounceSignatures2) Decode(r io.Reader, _ uint32) error {
+	return ReadElements(r,
+		&a.ChannelID,
+		&a.ShortChannelID,
+		&a.PartialSignature,
+		&a.ExtraOpaqueData,
+	)
+}
+
+// Encode serializes the target AnnounceSignatures2 into the passed io.Writer
+// observing the protocol version specified.
+//
+// This is part of the lnwire.Message interface.
+func (a *AnnounceSignatures2) Encode(w *bytes.Buffer, _ uint32) error {
+	if err := WriteChannelID(w, a.ChannelID); err != nil {
+		return err
+	}
+
+	if err := WriteShortChannelID(w, a.ShortChannelID); err != nil {
+		return err
+	}
+
+	if err := WriteElement(w, a.PartialSignature); err != nil {
+		return err
+	}
+
+	return WriteBytes(w, a.ExtraOpaqueData)
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the lnwire.Message interface.
+func (a *AnnounceSignatures2) MsgType() MessageType {
+	return MsgAnnounceSignatures2
+}
+
+// SCID returns the ShortChannelID of the channel.
+//
+// NOTE: this is part of the AnnounceSignatures interface.
+func (a *AnnounceSignatures2) SCID() ShortChannelID {
+	return a.ShortChannelID
+}
+
+// ChanID returns the ChannelID identifying the channel.
+//
+// NOTE: this is part of the AnnounceSignatures interface.
+func (a *AnnounceSignatures2) ChanID() ChannelID {
+	return a.ChannelID
+}