lnwire: add a ChannelAnnouncement interface

Add a new ChannelAnnouncement interface and ensure that
ChannelAnnouncement1 implements it.

lnwire/interfaces.go

@@ -1,5 +1,7 @@
 package lnwire
 
+import "github.com/btcsuite/btcd/chaincfg/chainhash"
+
 // AnnounceSignatures is an interface that represents a message used to
 // exchange signatures of a ChannelAnnouncment message during the funding flow.
 type AnnounceSignatures interface {
@@ -11,3 +13,24 @@ type AnnounceSignatures interface {
 
 	Message
 }
+
+// ChannelAnnouncement is an interface that must be satisfied by any message
+// used to announce and prove the existence of a channel.
+type ChannelAnnouncement interface {
+	// SCID returns the short channel ID of the channel.
+	SCID() ShortChannelID
+
+	// GetChainHash returns the hash of the chain which this channel's
+	// funding transaction is confirmed in.
+	GetChainHash() chainhash.Hash
+
+	// Node1KeyBytes returns the bytes representing the public key of node
+	// 1 in the channel.
+	Node1KeyBytes() [33]byte
+
+	// Node2KeyBytes returns the bytes representing the public key of node
+	// 2 in the channel.
+	Node2KeyBytes() [33]byte
+
+	Message
+}