multi: add tapscript root to gossip message

discovery/gossiper.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channeldb/models"
+	"github.com/lightningnetwork/lnd/fn"
 	"github.com/lightningnetwork/lnd/graph"
 	"github.com/lightningnetwork/lnd/keychain"
 	"github.com/lightningnetwork/lnd/kvdb"
@@ -82,9 +83,10 @@ var (
 // can provide that serve useful when processing a specific network
 // announcement.
 type optionalMsgFields struct {
-	capacity     *btcutil.Amount
-	channelPoint *wire.OutPoint
-	remoteAlias  *lnwire.ShortChannelID
+	capacity      *btcutil.Amount
+	channelPoint  *wire.OutPoint
+	remoteAlias   *lnwire.ShortChannelID
+	tapscriptRoot fn.Option[chainhash.Hash]
 }
 
 // apply applies the optional fields within the functional options.
@@ -115,6 +117,14 @@ func ChannelPoint(op wire.OutPoint) OptionalMsgField {
 	}
 }
 
+// TapscriptRoot is an optional field that lets the gossiper know of the root of
+// the tapscript tree for a custom channel.
+func TapscriptRoot(root fn.Option[chainhash.Hash]) OptionalMsgField {
+	return func(f *optionalMsgFields) {
+		f.tapscriptRoot = root
+	}
+}
+
 // RemoteAlias is an optional field that lets the gossiper know that a locally
 // sent channel update is actually an update for the peer that should replace
 // the ShortChannelID field with the remote's alias. This is only used for
@@ -2578,6 +2588,9 @@ func (d *AuthenticatedGossiper) handleChanAnnouncement(nMsg *networkMsg,
 			cp := *nMsg.optionalMsgFields.channelPoint
 			edge.ChannelPoint = cp
 		}
+
+		// Optional tapscript root for custom channels.
+		edge.TapscriptRoot = nMsg.optionalMsgFields.tapscriptRoot
 	}
 
 	log.Debugf("Adding edge for short_chan_id: %v", scid.ToUint64())