Add aux channel closer support to RBF cooperative close flow

config.go

@@ -1944,7 +1944,8 @@ func (c *Config) ImplementationConfig(
 			c, ltndLog, interceptor,
 			c.RemoteSigner.MigrateWatchOnly,
 		)
-		return &ImplementationCfg{
+
+		implCfg := &ImplementationCfg{
 			GrpcRegistrar:     rpcImpl,
 			RestRegistrar:     rpcImpl,
 			ExternalValidator: rpcImpl,
@@ -1954,17 +1955,29 @@ func (c *Config) ImplementationConfig(
 			WalletConfigBuilder: rpcImpl,
 			ChainControlBuilder: rpcImpl,
 		}
+
+		if c.Dev.NeedMockAuxChanCloser() {
+			//nolint:ll
+			implCfg.AuxChanCloser = c.Dev.GetMockAuxChanCloserValueForTest()
+		}
+
+		return implCfg
 	}
 
 	defaultImpl := NewDefaultWalletImpl(c, ltndLog, interceptor, false)
-	return &ImplementationCfg{
+	implCfg := &ImplementationCfg{
 		GrpcRegistrar:       defaultImpl,
 		RestRegistrar:       defaultImpl,
 		ExternalValidator:   defaultImpl,
 		DatabaseBuilder:     NewDefaultDatabaseBuilder(c, ltndLog),
 		WalletConfigBuilder: defaultImpl,
 		ChainControlBuilder: defaultImpl,
 	}
+	if c.Dev.NeedMockAuxChanCloser() {
+		implCfg.AuxChanCloser = c.Dev.GetMockAuxChanCloserValueForTest()
+	}
+
+	return implCfg
 }
 
 // CleanAndExpandPath expands environment variables and leading ~ in the

docs/release-notes/release-notes-0.22.0.md

@@ -30,6 +30,8 @@
 
 ## Functional Enhancements
 
+* [Extend the RBF cooperative close flow to support auxiliary channel closers](https://github.com/lightningnetwork/lnd/pull/10817) by propagating shutdown custom records, deriving and preserving auxiliary close outputs across fee updates, exposing final close output details in close notifications.
+
 ## RPC Additions
 
 * The `routerrpc.EstimateRouteFee` RPC now supports [restricting fee estimates

itest/list_on_test.go

@@ -755,6 +755,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "rbf coop close",
 		TestFunc: testCoopCloseRbf,
 	},
+	{
+		Name:     "rbf coop close with aux close outputs",
+		TestFunc: testCoopCloseRbfWithAuxCloseOutputs,
+	},
 	{
 		Name:     "rbf coop close disconnect",
 		TestFunc: testRBFCoopCloseDisconnect,

itest/lnd_coop_close_rbf_test.go

@@ -1,11 +1,13 @@
 package itest
 
 import (
+	"bytes"
 	"fmt"
 	"testing"
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
+	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntest"
 	"github.com/lightningnetwork/lnd/lntest/node"
@@ -206,6 +208,83 @@ func testCoopCloseRbf(ht *lntest.HarnessTest) {
 	}
 }
 
+// testCoopCloseRbfWithAuxCloseOutputs tests that
+// AuxCloseOutputs are included in the TxOuts when AuxChanCloser exists
+// and are preserved across fee updates.
+func testCoopCloseRbfWithAuxCloseOutputs(ht *lntest.HarnessTest) {
+	ht.SetFeeEstimate(250)
+	ht.SetFeeEstimateWithConf(250, 6)
+
+	rbfCoopFlags := []string{
+		"--protocol.rbf-coop-close",
+		"--dev.mock-aux-chan-closer"}
+	params := lntest.OpenChannelParams{
+		Amt:     btcutil.Amount(10_000_000),
+		PushAmt: btcutil.Amount(5_000_000),
+	}
+	cfgs := [][]string{rbfCoopFlags, rbfCoopFlags}
+	chanPoints, nodes := ht.CreateSimpleNetwork(cfgs, params)
+	alice, bob := nodes[0], nodes[1]
+	chanPoint := chanPoints[0]
+
+	aliceFeeRate := chainfee.SatPerVByte(5)
+	aliceCloseStream, aliceCloseUpdate := ht.CloseChannelAssertPending(
+		alice, chanPoint, false,
+		lntest.WithCoopCloseFeeRate(aliceFeeRate),
+		lntest.WithLocalTxNotify(),
+	)
+
+	alicePendingUpdate := aliceCloseUpdate.GetClosePending()
+	checkAdditionalOutputs(ht, chainhash.Hash(alicePendingUpdate.Txid))
+
+	bobFeeRate := aliceFeeRate * 2
+	_, bobCloseUpdate := ht.CloseChannelAssertPending(
+		bob, chanPoint, false, lntest.WithCoopCloseFeeRate(bobFeeRate),
+		lntest.WithLocalTxNotify(),
+	)
+
+	bobPendingUpdate := bobCloseUpdate.GetClosePending()
+	checkAdditionalOutputs(ht, chainhash.Hash(bobPendingUpdate.Txid))
+
+	aliceCloseUpdate, err := ht.ReceiveCloseChannelUpdate(aliceCloseStream)
+	require.NoError(ht, err)
+	alicePendingUpdate = aliceCloseUpdate.GetClosePending()
+	checkAdditionalOutputs(ht, chainhash.Hash(alicePendingUpdate.Txid))
+
+	block := ht.MineBlocksAndAssertNumTxes(1, 1)[0]
+
+	aliceClosingTxid := ht.WaitForChannelCloseEvent(aliceCloseStream)
+	checkAdditionalOutputs(ht, aliceClosingTxid)
+	ht.AssertTxInBlock(block, aliceClosingTxid)
+}
+
+func checkAdditionalOutputs(ht *lntest.HarnessTest, txid chainhash.Hash) {
+	tx := ht.Miner().GetRawTransaction(txid)
+	txOuts := tx.MsgTx().TxOut
+	require.Equal(ht, 3, len(txOuts))
+
+	expectedTxOut := wire.TxOut{
+		Value: 50_000,
+		PkScript: []byte{
+			0x00, 0x14, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,
+			0x11, 0x11, 0x11, 0x11,
+		},
+	}
+	contains := false
+	for _, txOut := range txOuts {
+		if txOut.Value == expectedTxOut.Value &&
+			bytes.Equal(
+				txOut.PkScript,
+				expectedTxOut.PkScript,
+			) {
+
+			contains = true
+		}
+	}
+	require.True(ht, contains)
+}
+
 // testRBFCoopCloseDisconnect tests that when a node disconnects that the node
 // is properly disconnected.
 func testRBFCoopCloseDisconnect(ht *lntest.HarnessTest) {

lncfg/dev.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/lightningnetwork/lnd/fn/v2"
+	"github.com/lightningnetwork/lnd/lnwallet/chancloser"
 	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
 )
 
@@ -21,6 +22,18 @@ func IsDevBuild() bool {
 // should always remain empty.
 type DevConfig struct{}
 
+// NeedMockAuxChanCloser returns the config value for MockAuxChanCloser,
+// which is always false for production build.
+func (d *DevConfig) NeedMockAuxChanCloser() bool {
+	return false
+}
+
+// GetMockAuxChanCloserValueForTest returns the mock AuxChanCloser value
+// which is always None for production build
+func (d *DevConfig) GetMockAuxChanCloserValueForTest() fn.Option[chancloser.AuxChanCloser] {
+	return fn.None[chancloser.AuxChanCloser]()
+}
+
 // ChannelReadyWait returns the config value, which is always 0 for production
 // build.
 func (d *DevConfig) ChannelReadyWait() time.Duration {

lncfg/dev_integration.go

@@ -5,8 +5,13 @@ package lncfg
 import (
 	"time"
 
+	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/fn/v2"
+	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/lnwallet/chancloser"
 	"github.com/lightningnetwork/lnd/lnwallet/chanfunding"
+	"github.com/lightningnetwork/lnd/lnwallet/types"
+	"github.com/lightningnetwork/lnd/lnwire"
 )
 
 // IsDevBuild returns a bool to indicate whether we are in a development
@@ -30,6 +35,63 @@ type DevConfig struct {
 	UnsafeConnect               bool          `long:"unsafeconnect" description:"Allow the rpcserver to connect to a peer even if there's already a connection."`
 	ForceChannelCloseConfs      uint32        `long:"force-channel-close-confs" description:"Force a specific number of confirmations for channel closes (dev/test only)"`
 	MinFwdHistoryAge            time.Duration `long:"min-fwd-history-age" description:"Minimum age of forwarding events before they can be deleted via DeleteForwardingHistory (dev/test only, default: 1h)"`
+	MockAuxChanCloser           bool          `long:"mock-aux-chan-closer" description:"Set the mock AuxChanCloser for tests."`
+}
+
+// NeedMockAuxChanCloser returns the config value for MockAuxChanCloser,
+// indicating whether the integration test needs a mock AuxChanCloser.
+func (d *DevConfig) NeedMockAuxChanCloser() bool {
+	return d.MockAuxChanCloser
+}
+
+// GetMockAuxChanCloserValueForTest returns the mock AuxChanCloser value
+// that can be used in integration tests.
+//
+//nolint:ll
+func (d *DevConfig) GetMockAuxChanCloserValueForTest() fn.Option[chancloser.AuxChanCloser] {
+	return fn.Some[chancloser.AuxChanCloser](&mockAuxChanCloser{})
+}
+
+// Mock implementation for AuxChanCloser.
+type mockAuxChanCloser struct{}
+
+func (m *mockAuxChanCloser) ShutdownBlob(
+	req types.AuxShutdownReq,
+) (fn.Option[lnwire.CustomRecords], error) {
+
+	return fn.None[lnwire.CustomRecords](), nil
+}
+
+func (m *mockAuxChanCloser) AuxCloseOutputs(
+	desc types.AuxCloseDesc,
+) (fn.Option[chancloser.AuxCloseOutputs], error) {
+
+	return fn.Some[chancloser.AuxCloseOutputs](
+		chancloser.AuxCloseOutputs{
+			ExtraCloseOutputs: []lnwallet.CloseOutput{
+				{
+					TxOut: wire.TxOut{
+						Value: 50_000,
+						PkScript: []byte{
+							0x00, 0x14, 0x11, 0x11,
+							0x11, 0x11, 0x11, 0x11,
+							0x11, 0x11, 0x11, 0x11,
+							0x11, 0x11, 0x11, 0x11,
+							0x11, 0x11, 0x11, 0x11,
+							0x11, 0x11,
+						},
+					},
+					IsLocal: desc.Initiator,
+				},
+			},
+		},
+	), nil
+}
+
+func (m *mockAuxChanCloser) FinalizeClose(desc types.AuxCloseDesc,
+	closeTx *wire.MsgTx) error {
+
+	return nil
 }
 
 // ChannelReadyWait returns the config value `ProcessChannelReadyWait`.

lnwallet/chancloser/rbf_coop_msg_mapper.go

@@ -67,6 +67,7 @@ func (r *RbfMsgMapper) MapMsg(wireMsg msgmux.PeerMsg) fn.Option[ProtocolEvent] {
 		return someEvent(&ShutdownReceived{
 			BlockHeight:         r.bestHeight(),
 			ShutdownScript:      msg.Address,
+			CustomRecords:       msg.CustomRecords,
 			RemoteShutdownNonce: remoteShutdownNonce,
 		})