multi: add coin selection strategy to channel funding

With this commit we prepare for the lnwallet channel funding logic to be
aware of the config-level coin selection strategy by adding it to the
wallet config.

config_builder.go

@@ -686,14 +686,15 @@ func (d *DefaultWalletImpl) BuildChainControl(
 	// Create, and start the lnwallet, which handles the core payment
 	// channel logic, and exposes control via proxy state machines.
 	lnWalletConfig := lnwallet.Config{
-		Database:         partialChainControl.Cfg.ChanStateDB,
-		Notifier:         partialChainControl.ChainNotifier,
-		WalletController: walletController,
-		Signer:           walletController,
-		FeeEstimator:     partialChainControl.FeeEstimator,
-		SecretKeyRing:    keyRing,
-		ChainIO:          walletController,
-		NetParams:        *walletConfig.NetParams,
+		Database:              partialChainControl.Cfg.ChanStateDB,
+		Notifier:              partialChainControl.ChainNotifier,
+		WalletController:      walletController,
+		Signer:                walletController,
+		FeeEstimator:          partialChainControl.FeeEstimator,
+		SecretKeyRing:         keyRing,
+		ChainIO:               walletController,
+		NetParams:             *walletConfig.NetParams,
+		CoinSelectionStrategy: walletConfig.CoinSelectionStrategy,
 	}
 
 	// The broadcast is already always active for neutrino nodes, so we
@@ -800,14 +801,15 @@ func (d *RPCSignerWalletImpl) BuildChainControl(
 	// Create, and start the lnwallet, which handles the core payment
 	// channel logic, and exposes control via proxy state machines.
 	lnWalletConfig := lnwallet.Config{
-		Database:         partialChainControl.Cfg.ChanStateDB,
-		Notifier:         partialChainControl.ChainNotifier,
-		WalletController: rpcKeyRing,
-		Signer:           rpcKeyRing,
-		FeeEstimator:     partialChainControl.FeeEstimator,
-		SecretKeyRing:    rpcKeyRing,
-		ChainIO:          walletController,
-		NetParams:        *walletConfig.NetParams,
+		Database:              partialChainControl.Cfg.ChanStateDB,
+		Notifier:              partialChainControl.ChainNotifier,
+		WalletController:      rpcKeyRing,
+		Signer:                rpcKeyRing,
+		FeeEstimator:          partialChainControl.FeeEstimator,
+		SecretKeyRing:         rpcKeyRing,
+		ChainIO:               walletController,
+		NetParams:             *walletConfig.NetParams,
+		CoinSelectionStrategy: walletConfig.CoinSelectionStrategy,
 	}
 
 	// We've created the wallet configuration now, so we can finish

funding/manager_test.go

@@ -20,6 +20,7 @@ import (
 	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/chainreg"
 	acpt "github.com/lightningnetwork/lnd/chanacceptor"
@@ -360,14 +361,15 @@ func createTestWallet(cdb *channeldb.ChannelStateDB, netParams *chaincfg.Params,
 	estimator chainfee.Estimator) (*lnwallet.LightningWallet, error) {
 
 	wallet, err := lnwallet.NewLightningWallet(lnwallet.Config{
-		Database:         cdb,
-		Notifier:         notifier,
-		SecretKeyRing:    keyRing,
-		WalletController: wc,
-		Signer:           signer,
-		ChainIO:          bio,
-		FeeEstimator:     estimator,
-		NetParams:        *netParams,
+		Database:              cdb,
+		Notifier:              notifier,
+		SecretKeyRing:         keyRing,
+		WalletController:      wc,
+		Signer:                signer,
+		ChainIO:               bio,
+		FeeEstimator:          estimator,
+		NetParams:             *netParams,
+		CoinSelectionStrategy: wallet.CoinSelectionLargest,
 	})
 	if err != nil {
 		return nil, err

lnwallet/chanfunding/wallet_assembler.go

@@ -9,6 +9,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil/txsort"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/keychain"
 )
@@ -207,6 +208,10 @@ type WalletConfig struct {
 	// CoinSource is what the WalletAssembler uses to list/locate coins.
 	CoinSource CoinSource
 
+	// CoinSelectionStrategy is the strategy that is used for selecting
+	// coins when funding a transaction.
+	CoinSelectionStrategy wallet.CoinSelectionStrategy
+
 	// CoinSelectionLocker allows the WalletAssembler to gain exclusive
 	// access to the current set of coins returned by the CoinSource.
 	CoinSelectLocker CoinSelectionLocker

lnwallet/config.go

@@ -2,6 +2,7 @@ package lnwallet
 
 import (
 	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/input"
@@ -57,4 +58,8 @@ type Config struct {
 	// passively rebroadcast transactions in the background until they're
 	// detected as being confirmed.
 	Rebroadcaster Rebroadcaster
+
+	// CoinSelectionStrategy is the strategy that is used for selecting
+	// coins when funding a transaction.
+	CoinSelectionStrategy wallet.CoinSelectionStrategy
 }

lnwallet/test/test_interface.go

@@ -27,6 +27,7 @@ import (
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcwallet/chain"
+	"github.com/btcsuite/btcwallet/wallet"
 	"github.com/btcsuite/btcwallet/walletdb"
 	_ "github.com/btcsuite/btcwallet/walletdb/bdb"
 	"github.com/davecgh/go-spew/spew"
@@ -349,14 +350,15 @@ func createTestWallet(tempTestDir string, miningNode *rpctest.Harness,
 	}
 
 	cfg := lnwallet.Config{
-		Database:         fullDB.ChannelStateDB(),
-		Notifier:         notifier,
-		SecretKeyRing:    keyRing,
-		WalletController: wc,
-		Signer:           signer,
-		ChainIO:          bio,
-		FeeEstimator:     chainfee.NewStaticEstimator(2500, 0),
-		NetParams:        *netParams,
+		Database:              fullDB.ChannelStateDB(),
+		Notifier:              notifier,
+		SecretKeyRing:         keyRing,
+		WalletController:      wc,
+		Signer:                signer,
+		ChainIO:               bio,
+		FeeEstimator:          chainfee.NewStaticEstimator(2500, 0),
+		NetParams:             *netParams,
+		CoinSelectionStrategy: wallet.CoinSelectionLargest,
 	}
 
 	wallet, err := lnwallet.NewLightningWallet(cfg)
@@ -2984,28 +2986,33 @@ func testSingleFunderExternalFundingTx(miner *rpctest.Harness,
 	// Simulating external funding negotiation, we'll now create the
 	// funding transaction for both parties. Utilizing existing tools,
 	// we'll create a new chanfunding.Assembler hacked by Alice's wallet.
-	aliceChanFunder := chanfunding.NewWalletAssembler(chanfunding.WalletConfig{
-		CoinSource:       lnwallet.NewCoinSource(alice),
-		CoinSelectLocker: alice,
-		CoinLocker:       alice,
-		Signer:           alice.Cfg.Signer,
-		DustLimit:        600,
-	})
+	aliceChanFunder := chanfunding.NewWalletAssembler(
+		chanfunding.WalletConfig{
+			CoinSource:            lnwallet.NewCoinSource(alice),
+			CoinSelectLocker:      alice,
+			CoinLocker:            alice,
+			Signer:                alice.Cfg.Signer,
+			DustLimit:             600,
+			CoinSelectionStrategy: wallet.CoinSelectionLargest,
+		},
+	)
 
 	// With the chan funder created, we'll now provision a funding intent,
 	// bind the keys we obtained above, and finally obtain our funding
 	// transaction and outpoint.
-	fundingIntent, err := aliceChanFunder.ProvisionChannel(&chanfunding.Request{
-		LocalAmt: btcutil.Amount(chanAmt),
-		MinConfs: 1,
-		FeeRate:  253,
-		ChangeAddr: func() (btcutil.Address, error) {
-			return alice.NewAddress(
-				lnwallet.WitnessPubKey, true,
-				lnwallet.DefaultAccountName,
-			)
+	fundingIntent, err := aliceChanFunder.ProvisionChannel(
+		&chanfunding.Request{
+			LocalAmt: btcutil.Amount(chanAmt),
+			MinConfs: 1,
+			FeeRate:  253,
+			ChangeAddr: func() (btcutil.Address, error) {
+				return alice.NewAddress(
+					lnwallet.WitnessPubKey, true,
+					lnwallet.DefaultAccountName,
+				)
+			},
 		},
-	})
+	)
 	require.NoError(t, err, "unable to perform coin selection")
 
 	// With our intent created, we'll instruct it to finalize the funding

lnwallet/wallet.go

@@ -852,7 +852,10 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 			CoinSelectLocker: l,
 			CoinLocker:       l,
 			Signer:           l.Cfg.Signer,
-			DustLimit:        DustLimitForSize(input.P2WSHSize),
+			DustLimit: DustLimitForSize(
+				input.P2WSHSize,
+			),
+			CoinSelectionStrategy: l.Cfg.CoinSelectionStrategy,
 		}
 		req.ChanFunder = chanfunding.NewWalletAssembler(cfg)
 	} else {