Merge pull request #6810 from Roasbeef/taproot-errwhere

multi: use taproot errwhere applicable for change/delivery/tower addresses

contractcourt/breacharbiter.go

@@ -1347,9 +1347,9 @@ func (b *BreachArbiter) createSweepTx(inputs []input.Input) (*wire.MsgTx,
 	spendableOutputs = make([]input.Input, 0, len(inputs))
 
 	// The justice transaction we construct will be a segwit transaction
-	// that pays to a p2wkh output. Components such as the version,
+	// that pays to a p2tr output. Components such as the version,
 	// nLockTime, and output are already included in the TxWeightEstimator.
-	weightEstimate.AddP2WKHOutput()
+	weightEstimate.AddP2TROutput()
 
 	// Next, we iterate over the breached outputs contained in the
 	// retribution info.  For each, we switch over the witness type such

docs/release-notes/release-notes-0.15.1.md

@@ -21,12 +21,15 @@
 
 ## Taproot
 
-[`lnd` will now refuse to start if it detects the full node backned does not
+[`lnd` will now refuse to start if it detects the full node backend does not
 support Tapoot](https://github.com/lightningnetwork/lnd/pull/6798).
 
 [`lnd` will now use taproot addresses for co-op closes if the remote peer
 supports the feature.](https://github.com/lightningnetwork/lnd/pull/6633)
 
+The [wallet also creates P2TR change addresses by
+default](https://github.com/lightningnetwork/lnd/pull/6810) in most cases.
+
 ## `lncli`
 
 * [Add `payment_addr` flag to

lnd.go

@@ -458,7 +458,7 @@ func Main(cfg *Config, lisCfg ListenerCfg, implCfg *ImplementationCfg,
 			Net:            cfg.net,
 			NewAddress: func() (btcutil.Address, error) {
 				return activeChainControl.Wallet.NewAddress(
-					lnwallet.WitnessPubKey, false,
+					lnwallet.TaprootPubkey, false,
 					lnwallet.DefaultAccountName,
 				)
 			},

lnwallet/chanfunding/coin_select.go

@@ -98,8 +98,8 @@ func calculateFees(utxos []Coin, feeRate chainfee.SatPerKWeight) (btcutil.Amount
 	requiredFeeNoChange := feeRate.FeeForWeight(totalWeight)
 
 	// Estimate the fee required for a transaction with a change output.
-	// Assume that change output is a P2WKH output.
-	weightEstimate.AddP2WKHOutput()
+	// Assume that change output is a P2TR output.
+	weightEstimate.AddP2TROutput()
 
 	// Now that we have added the change output, redo the fee
 	// estimate.
@@ -209,7 +209,8 @@ func CoinSelectSubtractFees(feeRate chainfee.SatPerKWeight, amt,
 	// Obtain fee estimates both with and without using a change
 	// output.
 	requiredFeeNoChange, requiredFeeWithChange, err := calculateFees(
-		selectedUtxos, feeRate)
+		selectedUtxos, feeRate,
+	)
 	if err != nil {
 		return nil, 0, 0, err
 	}

lnwallet/chanfunding/coin_select_test.go

@@ -44,7 +44,7 @@ func fundingFee(feeRate chainfee.SatPerKWeight, numInput int, // nolint:unparam
 
 	// Optionally count a change output.
 	if change {
-		weightEstimate.AddP2WKHOutput()
+		weightEstimate.AddP2TROutput()
 	}
 
 	totalWeight := int64(weightEstimate.Weight())
@@ -81,7 +81,7 @@ func TestCalculateFees(t *testing.T) {
 			},
 
 			expectedFeeNoChange:   487,
-			expectedFeeWithChange: 611,
+			expectedFeeWithChange: 659,
 			expectedErr:           nil,
 		},
 
@@ -97,7 +97,7 @@ func TestCalculateFees(t *testing.T) {
 			},
 
 			expectedFeeNoChange:   579,
-			expectedFeeWithChange: 703,
+			expectedFeeWithChange: 751,
 			expectedErr:           nil,
 		},
 

lnwallet/chanfunding/wallet_assembler.go

@@ -21,7 +21,7 @@ import (
 //
 // Steps to final channel provisioning:
 //  1. Call BindKeys to notify the intent which keys to use when constructing
-//  the multi-sig output.
+//     the multi-sig output.
 //  2. Call CompileFundingTx afterwards to obtain the funding transaction.
 //
 // If either of these steps fail, then the Cancel method MUST be called.

lnwallet/test/test_interface.go

@@ -2708,6 +2708,14 @@ var walletTests = []walletTestCase{
 		name: "change output spend confirmation",
 		test: testChangeOutputSpendConfirmation,
 	},
+	{
+		// TODO(guggero): this test should remain second until dual
+		// funding can properly exchange full UTXO information and we
+		// can use P2TR change outputs as the funding inputs for a dual
+		// funded channel.
+		name: "dual funder workflow",
+		test: testDualFundingReservationWorkflow,
+	},
 	{
 		name: "spend unconfirmed outputs",
 		test: testSpendUnconfirmed,
@@ -2744,10 +2752,6 @@ var walletTests = []walletTestCase{
 		name: "single funding workflow external funding tx",
 		test: testSingleFunderExternalFundingTx,
 	},
-	{
-		name: "dual funder workflow",
-		test: testDualFundingReservationWorkflow,
-	},
 	{
 		name: "output locking",
 		test: testFundingTransactionLockedOutputs,

lnwallet/wallet.go

@@ -775,7 +775,7 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 			FeeRate:      req.FundingFeePerKw,
 			ChangeAddr: func() (btcutil.Address, error) {
 				return l.NewAddress(
-					WitnessPubKey, true, DefaultAccountName,
+					TaprootPubkey, true, DefaultAccountName,
 				)
 			},
 		}

rpcserver.go

@@ -1330,7 +1330,7 @@ func (r *rpcServer) SendCoins(ctx context.Context,
 			// ensures this is an address the wallet knows about,
 			// allowing us to pass the reserved value check.
 			changeAddr, err := r.server.cc.Wallet.NewAddress(
-				lnwallet.WitnessPubKey, true,
+				lnwallet.TaprootPubkey, true,
 				lnwallet.DefaultAccountName,
 			)
 			if err != nil {

server.go

@@ -4534,7 +4534,8 @@ func newSweepPkScriptGen(
 
 	return func() ([]byte, error) {
 		sweepAddr, err := wallet.NewAddress(
-			lnwallet.WitnessPubKey, false, lnwallet.DefaultAccountName,
+			lnwallet.TaprootPubkey, false,
+			lnwallet.DefaultAccountName,
 		)
 		if err != nil {
 			return nil, err

sweep/tx_input_set.go

@@ -139,7 +139,7 @@ func newTxInputSet(wallet Wallet, feePerKW chainfee.SatPerKWeight,
 func (t *txInputSet) enoughInput() bool {
 	// If we have a change output above dust, then we certainly have enough
 	// inputs to the transaction.
-	if t.changeOutput >= lnwallet.DustLimitForSize(input.P2WPKHSize) {
+	if t.changeOutput >= lnwallet.DustLimitForSize(input.P2TRSize) {
 		return true
 	}
 

sweep/txgenerator.go

@@ -111,8 +111,8 @@ func generateInputPartitionings(sweepableInputs []txInput,
 		// continuing with the remaining inputs will only lead to sets
 		// with an even lower output value.
 		if !txInputs.enoughInput() {
-			// The change output is always a p2wpkh here.
-			dl := lnwallet.DustLimitForSize(input.P2WPKHSize)
+			// The change output is always a p2tr here.
+			dl := lnwallet.DustLimitForSize(input.P2TRSize)
 			log.Debugf("Set value %v (r=%v, c=%v) below dust "+
 				"limit of %v", txInputs.totalOutput(),
 				txInputs.requiredOutput, txInputs.changeOutput,

watchtower/lookout/justice_descriptor.go

@@ -10,6 +10,7 @@ import (
 	"github.com/btcsuite/btcd/btcutil/txsort"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
+	"github.com/davecgh/go-spew/spew"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/watchtower/blob"
 	"github.com/lightningnetwork/lnd/watchtower/wtdb"
@@ -228,8 +229,8 @@ func (p *JusticeDescriptor) assembleJusticeTxn(txWeight int64,
 		i := inputIndex[inp.outPoint]
 		justiceTxn.TxIn[i].Witness = inp.witness
 
-		// Validate the reconstructed witnesses to ensure they are valid
-		// for the breached inputs.
+		// Validate the reconstructed witnesses to ensure they are
+		// valid for the breached inputs.
 		vm, err := txscript.NewEngine(
 			inp.txOut.PkScript, justiceTxn, i,
 			txscript.StandardVerifyFlags,
@@ -239,7 +240,9 @@ func (p *JusticeDescriptor) assembleJusticeTxn(txWeight int64,
 			return nil, err
 		}
 		if err := vm.Execute(); err != nil {
-			return nil, err
+			log.Debugf("Failed to validate justice transaction: %s",
+				spew.Sdump(justiceTxn))
+			return nil, fmt.Errorf("error validating TX: %v", err)
 		}
 	}
 
@@ -300,6 +303,9 @@ func (p *JusticeDescriptor) CreateJusticeTxn() (*wire.MsgTx, error) {
 
 	sweepInputs = append(sweepInputs, toLocalInput)
 
+	log.Debugf("Found to local witness output=%#v, stack=%v",
+		toLocalInput.txOut, toLocalInput.witness)
+
 	// If the justice kit specifies that we have to sweep the to-remote
 	// output, we'll also try to assemble the output and add it to weight
 	// estimate if successful.
@@ -310,6 +316,9 @@ func (p *JusticeDescriptor) CreateJusticeTxn() (*wire.MsgTx, error) {
 		}
 		sweepInputs = append(sweepInputs, toRemoteInput)
 
+		log.Debugf("Found to remote witness output=%#v, stack=%v",
+			toRemoteInput.txOut, toRemoteInput.witness)
+
 		if p.JusticeKit.BlobType.IsAnchorChannel() {
 			weightEstimate.AddWitnessInput(input.ToRemoteConfirmedWitnessSize)
 		} else {

watchtower/wtclient/backup_task.go

@@ -7,6 +7,7 @@ import (
 	"github.com/btcsuite/btcd/btcec/v2"
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/btcutil/txsort"
+	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/btcsuite/btcd/txscript"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/channeldb"
@@ -151,6 +152,42 @@ func (t *backupTask) inputs() map[wire.OutPoint]input.Input {
 	return inputs
 }
 
+// addrType returns the type of an address after parsing it and matching it to
+// the set of known script templates.
+func addrType(pkScript []byte) txscript.ScriptClass {
+	// We pass in a set of dummy chain params here as they're only needed
+	// to make the address struct, which we're ignoring anyway (scripts are
+	// always the same, it's addresses that change across chains).
+	scriptClass, _, _, _ := txscript.ExtractPkScriptAddrs(
+		pkScript, &chaincfg.MainNetParams,
+	)
+
+	return scriptClass
+}
+
+// addScriptWeight parses the passed pkScript and adds the computed weight cost
+// were the script to be added to the justice transaction.
+func addScriptWeight(weightEstimate *input.TxWeightEstimator,
+	pkScript []byte) error {
+
+	switch addrType(pkScript) { //nolint: whitespace
+
+	case txscript.WitnessV0PubKeyHashTy:
+		weightEstimate.AddP2WKHOutput()
+
+	case txscript.WitnessV0ScriptHashTy:
+		weightEstimate.AddP2WSHOutput()
+
+	case txscript.WitnessV1TaprootTy:
+		weightEstimate.AddP2TROutput()
+
+	default:
+		return fmt.Errorf("invalid addr type: %v", addrType(pkScript))
+	}
+
+	return nil
+}
+
 // bindSession determines if the backupTask is compatible with the passed
 // SessionInfo's policy. If no error is returned, the task has been bound to the
 // session and can be queued to upload to the tower. Otherwise, the bind failed
@@ -192,13 +229,19 @@ func (t *backupTask) bindSession(session *wtdb.ClientSessionBody) error {
 		}
 	}
 
-	// All justice transactions have a p2wkh output paying to the victim.
-	weightEstimate.AddP2WKHOutput()
+	// All justice transactions will either use segwit v0 (p2wkh + p2wsh)
+	// or segwit v1 (p2tr).
+	if err := addScriptWeight(&weightEstimate, t.sweepPkScript); err != nil {
+		return err
+	}
 
 	// If the justice transaction has a reward output, add the output's
 	// contribution to the weight estimate.
 	if session.Policy.BlobType.Has(blob.FlagReward) {
-		weightEstimate.AddP2WKHOutput()
+		err := addScriptWeight(&weightEstimate, session.RewardPkScript)
+		if err != nil {
+			return err
+		}
 	}
 
 	if t.chanType.HasAnchors() != session.Policy.IsAnchorChannel() {

watchtower/wtclient/backup_task_internal_test.go

@@ -247,7 +247,7 @@ func genTaskTest(
 			RewardPkScript: rewardScript,
 		},
 		bindErr:        bindErr,
-		expSweepScript: makeAddrSlice(22),
+		expSweepScript: sweepAddr,
 		signer:         signer,
 		chanType:       chanType,
 	}
@@ -259,10 +259,18 @@ var (
 	blobTypeCommitReward = (blob.FlagCommitOutputs | blob.FlagReward).Type()
 
 	addr, _ = btcutil.DecodeAddress(
-		"mrX9vMRYLfVy1BnZbc5gZjuyaqH3ZW2ZHz", &chaincfg.TestNet3Params,
+		"tb1pw8gzj8clt3v5lxykpgacpju5n8xteskt7gxhmudu6pa70nwfhe6s3unsyk",
+		&chaincfg.TestNet3Params,
 	)
 
 	addrScript, _ = txscript.PayToAddrScript(addr)
+
+	sweepAddrScript, _ = btcutil.DecodeAddress(
+		"tb1qs3jyc9sf5kak3x0w99cav9u605aeu3t600xxx0",
+		&chaincfg.TestNet3Params,
+	)
+
+	sweepAddr, _ = txscript.PayToAddrScript(sweepAddrScript)
 )
 
 // TestBackupTaskBind tests the initialization and binding of a backupTask to a
@@ -297,9 +305,9 @@ func TestBackupTask(t *testing.T) {
 			expSweepCommitNoRewardBoth     int64                  = 299241
 			expSweepCommitNoRewardLocal    int64                  = 199514
 			expSweepCommitNoRewardRemote   int64                  = 99561
-			expSweepCommitRewardBoth       int64                  = 296117
-			expSweepCommitRewardLocal      int64                  = 197390
-			expSweepCommitRewardRemote     int64                  = 98437
+			expSweepCommitRewardBoth       int64                  = 296069
+			expSweepCommitRewardLocal      int64                  = 197342
+			expSweepCommitRewardRemote     int64                  = 98389
 			sweepFeeRateNoRewardRemoteDust chainfee.SatPerKWeight = 227500
 			sweepFeeRateRewardRemoteDust   chainfee.SatPerKWeight = 175350
 		)
@@ -307,9 +315,9 @@ func TestBackupTask(t *testing.T) {
 			expSweepCommitNoRewardBoth = 299236
 			expSweepCommitNoRewardLocal = 199513
 			expSweepCommitNoRewardRemote = 99557
-			expSweepCommitRewardBoth = 296112
-			expSweepCommitRewardLocal = 197389
-			expSweepCommitRewardRemote = 98433
+			expSweepCommitRewardBoth = 296064
+			expSweepCommitRewardLocal = 197341
+			expSweepCommitRewardRemote = 98385
 			sweepFeeRateNoRewardRemoteDust = 225400
 			sweepFeeRateRewardRemoteDust = 174100
 		}
@@ -436,7 +444,7 @@ func TestBackupTask(t *testing.T) {
 				"commit reward, to-remote output only, creates dust",
 				1,                            // stateNum
 				0,                            // toLocalAmt
-				100000,                       // toRemoteAmt
+				108221,                       // toRemoteAmt
 				blobTypeCommitReward,         // blobType
 				sweepFeeRateRewardRemoteDust, // sweepFeeRate
 				addrScript,                   // rewardScript

watchtower/wtclient/client_test.go

@@ -58,7 +58,8 @@ var (
 
 	// addr is the server's reward address given to watchtower clients.
 	addr, _ = btcutil.DecodeAddress(
-		"mrX9vMRYLfVy1BnZbc5gZjuyaqH3ZW2ZHz", &chaincfg.TestNet3Params,
+		"tb1pw8gzj8clt3v5lxykpgacpju5n8xteskt7gxhmudu6pa70nwfhe6s3unsyk",
+		&chaincfg.TestNet3Params,
 	)
 
 	addrScript, _ = txscript.PayToAddrScript(addr)

watchtower/wtpolicy/policy.go

@@ -6,7 +6,6 @@ import (
 
 	"github.com/btcsuite/btcd/btcutil"
 	"github.com/btcsuite/btcd/wire"
-	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnwallet"
 	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
 	"github.com/lightningnetwork/lnd/watchtower/blob"
@@ -156,7 +155,7 @@ func (p Policy) Validate() error {
 // of the justice transaction and subtracting an amount that satisfies the
 // policy's fee rate.
 func (p *Policy) ComputeAltruistOutput(totalAmt btcutil.Amount,
-	txWeight int64) (btcutil.Amount, error) {
+	txWeight int64, sweepScript []byte) (btcutil.Amount, error) {
 
 	txFee := p.SweepFeeRate.FeeForWeight(txWeight)
 	if txFee > totalAmt {
@@ -165,10 +164,9 @@ func (p *Policy) ComputeAltruistOutput(totalAmt btcutil.Amount,
 
 	sweepAmt := totalAmt - txFee
 
-	// TODO(conner): replace w/ configurable dust limit
-	// Check that the created outputs won't be dusty. The sweep pkscript is
-	// currently a p2wpkh, so we'll use that script's dust limit.
-	if sweepAmt < lnwallet.DustLimitForSize(input.P2WPKHSize) {
+	// Check that the created outputs won't be dusty. We'll base the dust
+	// computation on the type of the script itself.
+	if sweepAmt < lnwallet.DustLimitForSize(len(sweepScript)) {
 		return 0, ErrCreatesDust
 	}
 
@@ -180,7 +178,8 @@ func (p *Policy) ComputeAltruistOutput(totalAmt btcutil.Amount,
 // and reward rate. The reward to he tower is subtracted first, before
 // splitting the remaining balance amongst the victim and fees.
 func (p *Policy) ComputeRewardOutputs(totalAmt btcutil.Amount,
-	txWeight int64) (btcutil.Amount, btcutil.Amount, error) {
+	txWeight int64,
+	rewardScript []byte) (btcutil.Amount, btcutil.Amount, error) {
 
 	txFee := p.SweepFeeRate.FeeForWeight(txWeight)
 	if txFee > totalAmt {
@@ -198,10 +197,9 @@ func (p *Policy) ComputeRewardOutputs(totalAmt btcutil.Amount,
 	// input value.
 	sweepAmt := totalAmt - rewardAmt - txFee
 
-	// TODO(conner): replace w/ configurable dust limit
-	// Check that the created outputs won't be dusty. The sweep pkscript is
-	// currently a p2wpkh, so we'll use that script's dust limit.
-	if sweepAmt < lnwallet.DustLimitForSize(input.P2WPKHSize) {
+	// Check that the created outputs won't be dusty. We'll base the dust
+	// computation on the type of the script itself.
+	if sweepAmt < lnwallet.DustLimitForSize(len(rewardScript)) {
 		return 0, 0, ErrCreatesDust
 	}
 
@@ -231,15 +229,16 @@ func ComputeRewardAmount(total btcutil.Amount, base, rate uint32) btcutil.Amount
 	return rewardBase + proportional
 }
 
-// ComputeJusticeTxOuts constructs the justice transaction outputs for the given
-// policy. If the policy specifies a reward for the tower, there will be two
-// outputs paying to the victim and the tower. Otherwise there will be a single
-// output sweeping funds back to the victim. The totalAmt should be the sum of
-// any inputs used in the transaction. The passed txWeight should include the
-// weight of the outputs for the justice transaction, which is dependent on
-// whether the justice transaction has a reward. The sweepPkScript should be the
-// pkScript of the victim to which funds will be recovered. The rewardPkScript
-// is the pkScript of the tower where its reward will be deposited, and will be
+// ComputeJusticeTxOuts constructs the justice transaction outputs for the
+// given policy. If the policy specifies a reward for the tower, there will be
+// two outputs paying to the victim and the tower. Otherwise there will be a
+// single output sweeping funds back to the victim. The totalAmt should be the
+// sum of any inputs used in the transaction. The passed txWeight should
+// include the weight of the outputs for the justice transaction, which is
+// dependent on whether the justice transaction has a reward. The sweepPkScript
+// should be the pkScript of the victim to which funds will be recovered. The
+// rewardPkScript is the pkScript of the tower where its reward will be
+// deposited, and will be
 // ignored if the blob type does not specify a reward.
 func (p *Policy) ComputeJusticeTxOuts(totalAmt btcutil.Amount, txWeight int64,
 	sweepPkScript, rewardPkScript []byte) ([]*wire.TxOut, error) {
@@ -247,19 +246,19 @@ func (p *Policy) ComputeJusticeTxOuts(totalAmt btcutil.Amount, txWeight int64,
 	var outputs []*wire.TxOut
 
 	// If the policy specifies a reward for the tower, compute a split of
-	// the funds based on the policy's parameters. Otherwise, we will use an
-	// the altruist output computation and sweep as much of the funds back
-	// to the victim as possible.
+	// the funds based on the policy's parameters. Otherwise, we will use
+	// the altruist output computation and sweep as much of the funds
+	// back to the victim as possible.
 	if p.BlobType.Has(blob.FlagReward) {
 		// Using the total input amount and the transaction's weight,
-		// compute the sweep and reward amounts. This corresponds to the
-		// amount returned to the victim and the amount paid to the
+		// compute the sweep and reward amounts. This corresponds to
+		// the amount returned to the victim and the amount paid to the
 		// tower, respectively. To do so, the required transaction fee
 		// is subtracted from the total, and the remaining amount is
-		// divided according to the prenegotiated reward rate from the
+		// divided according to the pre negotiated reward rate from the
 		// client's session info.
 		sweepAmt, rewardAmt, err := p.ComputeRewardOutputs(
-			totalAmt, txWeight,
+			totalAmt, txWeight, rewardPkScript,
 		)
 		if err != nil {
 			return nil, err
@@ -280,7 +279,7 @@ func (p *Policy) ComputeJusticeTxOuts(totalAmt btcutil.Amount, txWeight int64,
 		// returned to the victim. To do so, the required transaction
 		// fee is subtracted from the total input amount.
 		sweepAmt, err := p.ComputeAltruistOutput(
-			totalAmt, txWeight,
+			totalAmt, txWeight, sweepPkScript,
 		)
 		if err != nil {
 			return nil, err

watchtower/wtserver/server_test.go

@@ -22,7 +22,8 @@ import (
 var (
 	// addr is the server's reward address given to watchtower clients.
 	addr, _ = btcutil.DecodeAddress(
-		"mrX9vMRYLfVy1BnZbc5gZjuyaqH3ZW2ZHz", &chaincfg.TestNet3Params,
+		"tb1pw8gzj8clt3v5lxykpgacpju5n8xteskt7gxhmudu6pa70nwfhe6s3unsyk",
+		&chaincfg.TestNet3Params,
 	)
 
 	addrScript, _ = txscript.PayToAddrScript(addr)