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sweep: move sweep tx generation into sweep package

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Sweep txes are currently generated in multiple locations. Moving
the sweep tx generation into a shared package will allow us to
reuse that logic.
This commit is contained in:
Joost Jager 2018-09-25 22:03:16 -07:00
parent 9fcc7ee390
commit 4dab405623
No known key found for this signature in database
GPG Key ID: AE6B0D042C8E38D9
6 changed files with 341 additions and 228 deletions
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10
log.go
View File

@ -1,11 +1,9 @@
package main
import (
"os"
"io"
"fmt"
"io"
"os"
"path/filepath"
"github.com/btcsuite/btcd/connmgr"
@ -24,6 +22,7 @@ import (
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/lightningnetwork/lnd/routing"
"github.com/lightningnetwork/lnd/signal"
"github.com/lightningnetwork/lnd/sweep"
)
// Loggers per subsystem. A single backend logger is created and all subsystem
@ -65,6 +64,7 @@ var (
atplLog = build.NewSubLogger("ATPL", backendLog.Logger)
cnctLog = build.NewSubLogger("CNCT", backendLog.Logger)
sphxLog = build.NewSubLogger("SPHX", backendLog.Logger)
swprLog = build.NewSubLogger("SWPR", backendLog.Logger)
)
// Initialize package-global logger variables.
@ -81,6 +81,7 @@ func init() {
contractcourt.UseLogger(cnctLog)
sphinx.UseLogger(sphxLog)
signal.UseLogger(ltndLog)
sweep.UseLogger(swprLog)
}
// subsystemLoggers maps each subsystem identifier to its associated logger.
@ -103,6 +104,7 @@ var subsystemLoggers = map[string]btclog.Logger{
"ATPL": atplLog,
"CNCT": cnctLog,
"SPHX": sphxLog,
"SWPR": swprLog,
}
// initLogRotator initializes the logging rotator to write logs to logFile and

26
server.go
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@ -6,6 +6,7 @@ import (
"crypto/rand"
"encoding/hex"
"fmt"
"github.com/lightningnetwork/lnd/sweep"
"image/color"
"math/big"
"net"
@ -58,6 +59,10 @@ const (
// durations exceeding this value will be eligible to have their
// backoffs reduced.
defaultStableConnDuration = 10 * time.Minute
// sweepTxConfirmationTarget assigns a confirmation target for sweep
// txes on which the fee calculation will be based.
sweepTxConfirmationTarget = 6
)
var (
@ -581,19 +586,24 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB, cc *chainControl,
return nil, err
}
sweeper := sweep.New(&sweep.UtxoSweeperConfig{
Estimator: cc.feeEstimator,
GenSweepScript: func() ([]byte, error) {
return newSweepPkScript(cc.wallet)
},
Signer: cc.wallet.Cfg.Signer,
ConfTarget: sweepTxConfirmationTarget,
})
s.utxoNursery = newUtxoNursery(&NurseryConfig{
ChainIO: cc.chainIO,
ConfDepth: 1,
FetchClosedChannels: chanDB.FetchClosedChannels,
FetchClosedChannel: chanDB.FetchClosedChannel,
Estimator: cc.feeEstimator,
GenSweepScript: func() ([]byte, error) {
return newSweepPkScript(cc.wallet)
},
Notifier: cc.chainNotifier,
PublishTransaction: cc.wallet.PublishTransaction,
Signer: cc.wallet.Cfg.Signer,
Store: utxnStore,
Notifier: cc.chainNotifier,
PublishTransaction: cc.wallet.PublishTransaction,
Store: utxnStore,
Sweeper: sweeper,
})
// Construct a closure that wraps the htlcswitch's CloseLink method.

45
sweep/log.go Normal file
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@ -0,0 +1,45 @@
package sweep
import (
"github.com/btcsuite/btclog"
"github.com/lightningnetwork/lnd/build"
)
// log is a logger that is initialized with no output filters. This
// means the package will not perform any logging by default until the caller
// requests it.
var log btclog.Logger
// The default amount of logging is none.
func init() {
UseLogger(build.NewSubLogger("SWPR", nil))
}
// DisableLog disables all library log output. Logging output is disabled
// by default until UseLogger is called.
func DisableLog() {
UseLogger(btclog.Disabled)
}
// UseLogger uses a specified Logger to output package logging info.
// This should be used in preference to SetLogWriter if the caller is also
// using btclog.
func UseLogger(logger btclog.Logger) {
log = logger
}
// logClosure is used to provide a closure over expensive logging operations so
// don't have to be performed when the logging level doesn't warrant it.
type logClosure func() string
// String invokes the underlying function and returns the result.
func (c logClosure) String() string {
return c()
}
// newLogClosure returns a new closure over a function that returns a string
// which itself provides a Stringer interface so that it can be used with the
// logging system.
func newLogClosure(c func() string) logClosure {
return logClosure(c)
}

249
sweep/sweeper.go Normal file
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@ -0,0 +1,249 @@
package sweep
import (
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/txscript"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
"github.com/lightningnetwork/lnd/lnwallet"
)
// UtxoSweeper provides the functionality to generate sweep txes. The plan is to
// extend UtxoSweeper in the future to also manage the actual sweeping process
// by itself.
type UtxoSweeper struct {
cfg *UtxoSweeperConfig
}
// UtxoSweeperConfig contains dependencies of UtxoSweeper.
type UtxoSweeperConfig struct {
// GenSweepScript generates a P2WKH script belonging to the wallet where
// funds can be swept.
GenSweepScript func() ([]byte, error)
// Estimator is used when crafting sweep transactions to estimate the
// necessary fee relative to the expected size of the sweep transaction.
Estimator lnwallet.FeeEstimator
// Signer is used by the sweeper to generate valid witnesses at the
// time the incubated outputs need to be spent.
Signer lnwallet.Signer
// ConfTarget specifies a target for the number of blocks until an
// initial confirmation.
ConfTarget uint32
}
// New returns a new UtxoSweeper instance.
func New(cfg *UtxoSweeperConfig) *UtxoSweeper {
return &UtxoSweeper{
cfg: cfg,
}
}
// CreateSweepTx accepts a list of outputs and signs and generates a txn that
// spends from them. This method also makes an accurate fee estimate before
// generating the required witnesses.
//
// The value of currentBlockHeight argument will be set as the tx locktime. This
// function assumes that all CLTV inputs will be unlocked after
// currentBlockHeight. Reasons not to use the maximum of all actual CLTV expiry
// values of the inputs:
//
// - Make handling re-orgs easier.
// - Thwart future possible fee sniping attempts.
// - Make us blend in with the bitcoind wallet.
func (s *UtxoSweeper) CreateSweepTx(inputs []CsvSpendableOutput,
currentBlockHeight uint32) (*wire.MsgTx, error) {
// Create a transaction which sweeps all the newly mature outputs into
// an output controlled by the wallet.
// TODO(roasbeef): can be more intelligent about buffering outputs to
// be more efficient on-chain.
// Assemble the inputs into a slice csv spendable outputs, and also a
// set of regular spendable outputs. The set of regular outputs are CLTV
// locked outputs that have had their timelocks expire.
var (
csvOutputs []CsvSpendableOutput
cltvOutputs []SpendableOutput
weightEstimate lnwallet.TxWeightEstimator
)
// Allocate enough room for both types of outputs.
csvOutputs = make([]CsvSpendableOutput, 0, len(inputs))
cltvOutputs = make([]SpendableOutput, 0, len(inputs))
// Our sweep transaction will pay to a single segwit p2wkh address,
// ensure it contributes to our weight estimate.
weightEstimate.AddP2WKHOutput()
// For each output, use its witness type to determine the estimate
// weight of its witness, and add it to the proper set of spendable
// outputs.
for i := range inputs {
input := inputs[i]
switch input.WitnessType() {
// Outputs on a past commitment transaction that pay directly
// to us.
case lnwallet.CommitmentTimeLock:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// Outgoing second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case lnwallet.HtlcOfferedTimeoutSecondLevel:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// Incoming second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case lnwallet.HtlcAcceptedSuccessSecondLevel:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// An HTLC on the commitment transaction of the remote party,
// that has had its absolute timelock expire.
case lnwallet.HtlcOfferedRemoteTimeout:
weightEstimate.AddWitnessInput(
lnwallet.AcceptedHtlcTimeoutWitnessSize,
)
cltvOutputs = append(cltvOutputs, input)
default:
log.Warnf("kindergarten output in nursery store "+
"contains unexpected witness type: %v",
input.WitnessType())
continue
}
}
log.Infof("Creating sweep transaction for %v CSV inputs, %v CLTV "+
"inputs", len(csvOutputs), len(cltvOutputs))
txWeight := int64(weightEstimate.Weight())
return s.populateSweepTx(txWeight, currentBlockHeight, csvOutputs, cltvOutputs)
}
// populateSweepTx populate the final sweeping transaction with all witnesses
// in place for all inputs using the provided txn fee. The created transaction
// has a single output sending all the funds back to the source wallet, after
// accounting for the fee estimate.
func (s *UtxoSweeper) populateSweepTx(txWeight int64, currentBlockHeight uint32,
csvInputs []CsvSpendableOutput,
cltvInputs []SpendableOutput) (*wire.MsgTx, error) {
// Generate the receiving script to which the funds will be swept.
pkScript, err := s.cfg.GenSweepScript()
if err != nil {
return nil, err
}
// Sum up the total value contained in the inputs.
var totalSum btcutil.Amount
for _, o := range csvInputs {
totalSum += o.Amount()
}
for _, o := range cltvInputs {
totalSum += o.Amount()
}
// Using the txn weight estimate, compute the required txn fee.
feePerKw, err := s.cfg.Estimator.EstimateFeePerKW(s.cfg.ConfTarget)
if err != nil {
return nil, err
}
log.Debugf("Using %v sat/kw for sweep tx", int64(feePerKw))
txFee := feePerKw.FeeForWeight(txWeight)
// Sweep as much possible, after subtracting txn fees.
sweepAmt := int64(totalSum - txFee)
// Create the sweep transaction that we will be building. We use
// version 2 as it is required for CSV. The txn will sweep the amount
// after fees to the pkscript generated above.
sweepTx := wire.NewMsgTx(2)
sweepTx.AddTxOut(&wire.TxOut{
PkScript: pkScript,
Value: sweepAmt,
})
// We'll also ensure that the transaction has the required lock time if
// we're sweeping any cltvInputs.
if len(cltvInputs) > 0 {
sweepTx.LockTime = currentBlockHeight
}
// Add all inputs to the sweep transaction. Ensure that for each
// csvInput, we set the sequence number properly.
for _, input := range csvInputs {
sweepTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: *input.OutPoint(),
Sequence: input.BlocksToMaturity(),
})
}
for _, input := range cltvInputs {
sweepTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: *input.OutPoint(),
})
}
// Before signing the transaction, check to ensure that it meets some
// basic validity requirements.
// TODO(conner): add more control to sanity checks, allowing us to delay
// spending "problem" outputs, e.g. possibly batching with other classes
// if fees are too low.
btx := btcutil.NewTx(sweepTx)
if err := blockchain.CheckTransactionSanity(btx); err != nil {
return nil, err
}
hashCache := txscript.NewTxSigHashes(sweepTx)
// With all the inputs in place, use each output's unique witness
// function to generate the final witness required for spending.
addWitness := func(idx int, tso SpendableOutput) error {
witness, err := tso.BuildWitness(
s.cfg.Signer, sweepTx, hashCache, idx,
)
if err != nil {
return err
}
sweepTx.TxIn[idx].Witness = witness
return nil
}
// Finally we'll attach a valid witness to each csv and cltv input
// within the sweeping transaction.
for i, input := range csvInputs {
if err := addWitness(i, input); err != nil {
return nil, err
}
}
// Add offset to relative indexes so cltv witnesses don't overwrite csv
// witnesses.
offset := len(csvInputs)
for i, input := range cltvInputs {
if err := addWitness(offset+i, input); err != nil {
return nil, err
}
}
return sweepTx, nil
}

224
utxonursery.go
View File

@ -9,7 +9,6 @@ import (
"sync"
"sync/atomic"
"github.com/btcsuite/btcd/blockchain"
"github.com/btcsuite/btcd/txscript"
"github.com/btcsuite/btcd/wire"
"github.com/btcsuite/btcutil"
@ -193,14 +192,6 @@ type NurseryConfig struct {
FetchClosedChannel func(chanID *wire.OutPoint) (
*channeldb.ChannelCloseSummary, error)
// Estimator is used when crafting sweep transactions to estimate the
// necessary fee relative to the expected size of the sweep transaction.
Estimator lnwallet.FeeEstimator
// GenSweepScript generates a P2WKH script belonging to the wallet where
// funds can be swept.
GenSweepScript func() ([]byte, error)
// Notifier provides the utxo nursery the ability to subscribe to
// transaction confirmation events, which advance outputs through their
// persistence state transitions.
@ -210,13 +201,13 @@ type NurseryConfig struct {
// transaction to the appropriate network.
PublishTransaction func(*wire.MsgTx) error
// Signer is used by the utxo nursery to generate valid witnesses at the
// time the incubated outputs need to be spent.
Signer lnwallet.Signer
// Store provides access to and modification of the persistent state
// maintained about the utxo nursery's incubating outputs.
Store NurseryStore
// Sweeper provides functionality to generate sweep transactions.
// Nursery uses this to sweep final outputs back into the wallet.
Sweeper *sweep.UtxoSweeper
}
// utxoNursery is a system dedicated to incubating time-locked outputs created
@ -880,7 +871,15 @@ func (u *utxoNursery) graduateClass(classHeight uint32) error {
// generated a sweep txn for this height. Generate one if there
// are kindergarten outputs or cltv crib outputs to be spent.
if len(kgtnOutputs) > 0 {
finalTx, err = u.createSweepTx(kgtnOutputs, classHeight)
csvSpendableOutputs := make([]sweep.CsvSpendableOutput,
len(kgtnOutputs))
for i := range kgtnOutputs {
csvSpendableOutputs[i] = &kgtnOutputs[i]
}
finalTx, err = u.cfg.Sweeper.CreateSweepTx(
csvSpendableOutputs, classHeight)
if err != nil {
utxnLog.Errorf("Failed to create sweep txn at "+
"height=%d", classHeight)
@ -936,203 +935,6 @@ func (u *utxoNursery) graduateClass(classHeight uint32) error {
return u.cfg.Store.GraduateHeight(classHeight)
}
// craftSweepTx accepts a list of kindergarten outputs, and baby
// outputs which don't require a second-layer claim, and signs and generates a
// signed txn that spends from them. This method also makes an accurate fee
// estimate before generating the required witnesses.
func (u *utxoNursery) createSweepTx(kgtnOutputs []kidOutput,
classHeight uint32) (*wire.MsgTx, error) {
// Create a transaction which sweeps all the newly mature outputs into
// an output controlled by the wallet.
// TODO(roasbeef): can be more intelligent about buffering outputs to
// be more efficient on-chain.
// Assemble the kindergarten class into a slice csv spendable outputs,
// and also a set of regular spendable outputs. The set of regular
// outputs are CLTV locked outputs that have had their timelocks
// expire.
var (
csvOutputs []sweep.CsvSpendableOutput
cltvOutputs []sweep.SpendableOutput
weightEstimate lnwallet.TxWeightEstimator
)
// Allocate enough room for both types of kindergarten outputs.
csvOutputs = make([]sweep.CsvSpendableOutput, 0, len(kgtnOutputs))
cltvOutputs = make([]sweep.SpendableOutput, 0, len(kgtnOutputs))
// Our sweep transaction will pay to a single segwit p2wkh address,
// ensure it contributes to our weight estimate.
weightEstimate.AddP2WKHOutput()
// For each kindergarten output, use its witness type to determine the
// estimate weight of its witness, and add it to the proper set of
// spendable outputs.
for i := range kgtnOutputs {
input := &kgtnOutputs[i]
switch input.WitnessType() {
// Outputs on a past commitment transaction that pay directly
// to us.
case lnwallet.CommitmentTimeLock:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// Outgoing second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case lnwallet.HtlcOfferedTimeoutSecondLevel:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// Incoming second layer HTLC's that have confirmed within the
// chain, and the output they produced is now mature enough to
// sweep.
case lnwallet.HtlcAcceptedSuccessSecondLevel:
weightEstimate.AddWitnessInput(
lnwallet.ToLocalTimeoutWitnessSize,
)
csvOutputs = append(csvOutputs, input)
// An HTLC on the commitment transaction of the remote party,
// that has had its absolute timelock expire.
case lnwallet.HtlcOfferedRemoteTimeout:
weightEstimate.AddWitnessInput(
lnwallet.AcceptedHtlcTimeoutWitnessSize,
)
cltvOutputs = append(cltvOutputs, input)
default:
utxnLog.Warnf("kindergarten output in nursery store "+
"contains unexpected witness type: %v",
input.WitnessType())
continue
}
}
utxnLog.Infof("Creating sweep transaction for %v CSV inputs, %v CLTV "+
"inputs", len(csvOutputs), len(cltvOutputs))
txWeight := int64(weightEstimate.Weight())
return u.populateSweepTx(txWeight, classHeight, csvOutputs, cltvOutputs)
}
// populateSweepTx populate the final sweeping transaction with all witnesses
// in place for all inputs using the provided txn fee. The created transaction
// has a single output sending all the funds back to the source wallet, after
// accounting for the fee estimate.
func (u *utxoNursery) populateSweepTx(txWeight int64, classHeight uint32,
csvInputs []sweep.CsvSpendableOutput,
cltvInputs []sweep.SpendableOutput) (*wire.MsgTx, error) {
// Generate the receiving script to which the funds will be swept.
pkScript, err := u.cfg.GenSweepScript()
if err != nil {
return nil, err
}
// Sum up the total value contained in the inputs.
var totalSum btcutil.Amount
for _, o := range csvInputs {
totalSum += o.Amount()
}
for _, o := range cltvInputs {
totalSum += o.Amount()
}
// Using the txn weight estimate, compute the required txn fee.
feePerKw, err := u.cfg.Estimator.EstimateFeePerKW(6)
if err != nil {
return nil, err
}
txFee := feePerKw.FeeForWeight(txWeight)
// Sweep as much possible, after subtracting txn fees.
sweepAmt := int64(totalSum - txFee)
// Create the sweep transaction that we will be building. We use
// version 2 as it is required for CSV. The txn will sweep the amount
// after fees to the pkscript generated above.
sweepTx := wire.NewMsgTx(2)
sweepTx.AddTxOut(&wire.TxOut{
PkScript: pkScript,
Value: sweepAmt,
})
// We'll also ensure that the transaction has the required lock time if
// we're sweeping any cltvInputs.
if len(cltvInputs) > 0 {
sweepTx.LockTime = classHeight
}
// Add all inputs to the sweep transaction. Ensure that for each
// csvInput, we set the sequence number properly.
for _, input := range csvInputs {
sweepTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: *input.OutPoint(),
Sequence: input.BlocksToMaturity(),
})
}
for _, input := range cltvInputs {
sweepTx.AddTxIn(&wire.TxIn{
PreviousOutPoint: *input.OutPoint(),
})
}
// Before signing the transaction, check to ensure that it meets some
// basic validity requirements.
// TODO(conner): add more control to sanity checks, allowing us to delay
// spending "problem" outputs, e.g. possibly batching with other classes
// if fees are too low.
btx := btcutil.NewTx(sweepTx)
if err := blockchain.CheckTransactionSanity(btx); err != nil {
return nil, err
}
hashCache := txscript.NewTxSigHashes(sweepTx)
// With all the inputs in place, use each output's unique witness
// function to generate the final witness required for spending.
addWitness := func(idx int, tso sweep.SpendableOutput) error {
witness, err := tso.BuildWitness(
u.cfg.Signer, sweepTx, hashCache, idx,
)
if err != nil {
return err
}
sweepTx.TxIn[idx].Witness = witness
return nil
}
// Finally we'll attach a valid witness to each csv and cltv input
// within the sweeping transaction.
for i, input := range csvInputs {
if err := addWitness(i, input); err != nil {
return nil, err
}
}
// Add offset to relative indexes so cltv witnesses don't overwrite csv
// witnesses.
offset := len(csvInputs)
for i, input := range cltvInputs {
if err := addWitness(offset+i, input); err != nil {
return nil, err
}
}
return sweepTx, nil
}
// sweepMatureOutputs generates and broadcasts the transaction that transfers
// control of funds from a prior channel commitment transaction to the user's
// wallet. The outputs swept were previously time locked (either absolute or

15
utxonursery_test.go
View File

@ -6,6 +6,7 @@ import (
"bytes"
"fmt"
"github.com/lightningnetwork/lnd/channeldb"
"github.com/lightningnetwork/lnd/sweep"
"io/ioutil"
"math"
"reflect"
@ -431,6 +432,14 @@ func createNurseryTestContext(t *testing.T,
notifier := newNurseryMockNotifier(t)
sweeper := sweep.New(&sweep.UtxoSweeperConfig{
GenSweepScript: func() ([]byte, error) {
return []byte{}, nil
},
Estimator: &mockFeeEstimator{},
Signer: &nurseryMockSigner{},
})
cfg := NurseryConfig{
Notifier: notifier,
FetchClosedChannels: func(pendingOnly bool) (
@ -445,11 +454,7 @@ func createNurseryTestContext(t *testing.T,
},
Store: storeIntercepter,
ChainIO: &mockChainIO{},
GenSweepScript: func() ([]byte, error) {
return []byte{}, nil
},
Estimator: &mockFeeEstimator{},
Signer: &nurseryMockSigner{},
Sweeper: sweeper,
}
publishChan := make(chan wire.MsgTx, 1)