peer: send taproot addrs during co-op close based on new feature bit

If the ShutdownAnySegwitOptional option is active, then we can safely
send these newer addresses.

peer/brontide.go

@@ -657,6 +657,13 @@ func (p *Brontide) initGossipSync() {
 	}
 }
 
+// taprootShutdownAllowed returns true if both parties have negotiated the
+// shutdown-any-segwit feature.
+func (p *Brontide) taprootShutdownAllowed() bool {
+	return p.RemoteFeatures().HasFeature(lnwire.ShutdownAnySegwitOptional) &&
+		p.LocalFeatures().HasFeature(lnwire.ShutdownAnySegwitOptional)
+}
+
 // QuitSignal is a method that should return a channel which will be sent upon
 // or closed once the backing peer exits. This allows callers using the
 // interface to cancel any processing in the event the backing implementation
@@ -2244,8 +2251,15 @@ func (p *Brontide) ChannelSnapshots() []*channeldb.ChannelSnapshot {
 // genDeliveryScript returns a new script to be used to send our funds to in
 // the case of a cooperative channel close negotiation.
 func (p *Brontide) genDeliveryScript() ([]byte, error) {
+	// We'll send a normal p2wkh address unless we've negotiated the
+	// shutdown-any-segwit feature.
+	addrType := lnwallet.WitnessPubKey
+	if p.taprootShutdownAllowed() {
+		addrType = lnwallet.TaprootPubkey
+	}
+
 	deliveryAddr, err := p.cfg.Wallet.NewAddress(
-		lnwallet.WitnessPubKey, false, lnwallet.DefaultAccountName,
+		addrType, false, lnwallet.DefaultAccountName,
 	)
 	if err != nil {
 		return nil, err

peer/brontide_test.go

@@ -55,6 +55,8 @@ func TestPeerChannelClosureAcceptFeeResponder(t *testing.T) {
 	mockLink := newMockUpdateHandler(chanID)
 	mockSwitch.links = append(mockSwitch.links, mockLink)
 
+	dummyDeliveryScript := genScript(t, p2wshAddress)
+
 	// We send a shutdown request to Alice. She will now be the responding
 	// node in this shutdown procedure. We first expect Alice to answer
 	// this shutdown request with a Shutdown message.
@@ -156,6 +158,8 @@ func TestPeerChannelClosureAcceptFeeInitiator(t *testing.T) {
 	mockLink := newMockUpdateHandler(chanID)
 	mockSwitch.links = append(mockSwitch.links, mockLink)
 
+	dummyDeliveryScript := genScript(t, p2wshAddress)
+
 	// We make Alice send a shutdown request.
 	updateChan := make(chan interface{}, 1)
 	errChan := make(chan error, 1)
@@ -281,6 +285,7 @@ func TestPeerChannelClosureFeeNegotiationsResponder(t *testing.T) {
 	// Bob sends a shutdown request to Alice. She will now be the responding
 	// node in this shutdown procedure. We first expect Alice to answer this
 	// Shutdown request with a Shutdown message.
+	dummyDeliveryScript := genScript(t, p2wshAddress)
 	alicePeer.chanCloseMsgs <- &closeMsg{
 		cid: chanID,
 		msg: lnwire.NewShutdown(chanID,
@@ -492,6 +497,7 @@ func TestPeerChannelClosureFeeNegotiationsInitiator(t *testing.T) {
 	aliceDeliveryScript := shutdownMsg.Address
 
 	// Bob will answer the Shutdown message with his own Shutdown.
+	dummyDeliveryScript := genScript(t, p2wshAddress)
 	respShutdown := lnwire.NewShutdown(chanID, dummyDeliveryScript)
 	alicePeer.chanCloseMsgs <- &closeMsg{
 		cid: chanID,

peer/test_utils.go

@@ -45,9 +45,6 @@ const (
 )
 
 var (
-	// Just use some arbitrary bytes as delivery script.
-	dummyDeliveryScript = channels.AlicesPrivKey
-
 	testKeyLoc = keychain.KeyLocator{Family: keychain.KeyFamilyNodeKey}
 )
 
@@ -368,26 +365,26 @@ func createTestPeer(notifier chainntnfs.ChainNotifier,
 	}
 
 	cfg := &Config{
-		Addr:        cfgAddr,
-		PubKeyBytes: pubKey,
-		ErrorBuffer: errBuffer,
-		ChainIO:     chainIO,
-		Switch:      mockSwitch,
-
+		Addr:              cfgAddr,
+		PubKeyBytes:       pubKey,
+		ErrorBuffer:       errBuffer,
+		ChainIO:           chainIO,
+		Switch:            mockSwitch,
 		ChanActiveTimeout: chanActiveTimeout,
 		InterceptSwitch: htlcswitch.NewInterceptableSwitch(
 			nil, testCltvRejectDelta, false,
 		),
-
 		ChannelDB:      dbAlice.ChannelStateDB(),
 		FeeEstimator:   estimator,
 		Wallet:         wallet,
 		ChainNotifier:  notifier,
 		ChanStatusMgr:  chanStatusMgr,
+		Features:       lnwire.NewFeatureVector(nil, lnwire.Features),
 		DisconnectPeer: func(b *btcec.PublicKey) error { return nil },
 	}
 
 	alicePeer := NewBrontide(*cfg)
+	alicePeer.remoteFeatures = lnwire.NewFeatureVector(nil, lnwire.Features)
 
 	chanID := lnwire.NewChanIDFromOutPoint(channelAlice.ChannelPoint())
 	alicePeer.activeChannels[chanID] = channelAlice