utxonursery: move spendable output structs to sweep package

This commit moves the output structs to a new package as a
preparation for moving more logic into that package.

breacharbiter.go

@@ -20,6 +20,7 @@ import (
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/htlcswitch"
 	"github.com/lightningnetwork/lnd/lnwallet"
+	"github.com/lightningnetwork/lnd/sweep"
 )
 
 var (
@@ -748,33 +749,6 @@ func (b *breachArbiter) handleBreachHandoff(breachEvent *ContractBreachEvent) {
 	go b.exactRetribution(cfChan, retInfo)
 }
 
-// SpendableOutput an interface which can be used by the breach arbiter to
-// construct a transaction spending from outputs we control.
-type SpendableOutput interface {
-	// Amount returns the number of satoshis contained within the output.
-	Amount() btcutil.Amount
-
-	// Outpoint returns the reference to the output being spent, used to
-	// construct the corresponding transaction input.
-	OutPoint() *wire.OutPoint
-
-	// WitnessType returns an enum specifying the type of witness that must
-	// be generated in order to spend this output.
-	WitnessType() lnwallet.WitnessType
-
-	// SignDesc returns a reference to a spendable output's sign descriptor,
-	// which is used during signing to compute a valid witness that spends
-	// this output.
-	SignDesc() *lnwallet.SignDescriptor
-
-	// BuildWitness returns a valid witness allowing this output to be
-	// spent, the witness should be attached to the transaction at the
-	// location determined by the given `txinIdx`.
-	BuildWitness(signer lnwallet.Signer, txn *wire.MsgTx,
-		hashCache *txscript.TxSigHashes,
-		txinIdx int) ([][]byte, error)
-}
-
 // breachedOutput contains all the information needed to sweep a breached
 // output. A breached output is an output that we are now entitled to due to a
 // revoked commitment transaction being broadcast.
@@ -852,7 +826,7 @@ func (bo *breachedOutput) BuildWitness(signer lnwallet.Signer, txn *wire.MsgTx,
 
 // Add compile-time constraint ensuring breachedOutput implements
 // SpendableOutput.
-var _ SpendableOutput = (*breachedOutput)(nil)
+var _ sweep.SpendableOutput = (*breachedOutput)(nil)
 
 // retributionInfo encapsulates all the data needed to sweep all the contested
 // funds within a channel whose contract has been breached by the prior
@@ -963,13 +937,13 @@ func (b *breachArbiter) createJusticeTx(
 	// outputs, while simultaneously computing the estimated weight of the
 	// transaction.
 	var (
-		spendableOutputs []SpendableOutput
+		spendableOutputs []sweep.SpendableOutput
 		weightEstimate   lnwallet.TxWeightEstimator
 	)
 
 	// Allocate enough space to potentially hold each of the breached
 	// outputs in the retribution info.
-	spendableOutputs = make([]SpendableOutput, 0, len(r.breachedOutputs))
+	spendableOutputs = make([]sweep.SpendableOutput, 0, len(r.breachedOutputs))
 
 	// The justice transaction we construct will be a segwit transaction
 	// that pays to a p2wkh output. Components such as the version,
@@ -1023,7 +997,7 @@ func (b *breachArbiter) createJusticeTx(
 // sweepSpendableOutputsTxn creates a signed transaction from a sequence of
 // spendable outputs by sweeping the funds into a single p2wkh output.
 func (b *breachArbiter) sweepSpendableOutputsTxn(txWeight int64,
-	inputs ...SpendableOutput) (*wire.MsgTx, error) {
+	inputs ...sweep.SpendableOutput) (*wire.MsgTx, error) {
 
 	// First, we obtain a new public key script from the wallet which we'll
 	// sweep the funds to.
@@ -1085,7 +1059,7 @@ func (b *breachArbiter) sweepSpendableOutputsTxn(txWeight int64,
 	// witness, and attaching it to the transaction. This function accepts
 	// an integer index representing the intended txin index, and the
 	// breached output from which it will spend.
-	addWitness := func(idx int, so SpendableOutput) error {
+	addWitness := func(idx int, so sweep.SpendableOutput) error {
 		// First, we construct a valid witness for this outpoint and
 		// transaction using the SpendableOutput's witness generation
 		// function.

sweep/input.go

@@ -0,0 +1,58 @@
+package sweep
+
+import (
+	"github.com/btcsuite/btcd/txscript"
+	"github.com/btcsuite/btcd/wire"
+	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/lnwallet"
+)
+
+// SpendableOutput an interface which can be used by the breach arbiter to
+// construct a transaction spending from outputs we control.
+type SpendableOutput interface {
+	// Amount returns the number of satoshis contained within the output.
+	Amount() btcutil.Amount
+
+	// Outpoint returns the reference to the output being spent, used to
+	// construct the corresponding transaction input.
+	OutPoint() *wire.OutPoint
+
+	// WitnessType returns an enum specifying the type of witness that must
+	// be generated in order to spend this output.
+	WitnessType() lnwallet.WitnessType
+
+	// SignDesc returns a reference to a spendable output's sign descriptor,
+	// which is used during signing to compute a valid witness that spends
+	// this output.
+	SignDesc() *lnwallet.SignDescriptor
+
+	// BuildWitness returns a valid witness allowing this output to be
+	// spent, the witness should be attached to the transaction at the
+	// location determined by the given `txinIdx`.
+	BuildWitness(signer lnwallet.Signer, txn *wire.MsgTx,
+		hashCache *txscript.TxSigHashes,
+		txinIdx int) ([][]byte, error)
+}
+
+// CsvSpendableOutput is a SpendableOutput that contains all of the information
+// necessary to construct, sign, and sweep an output locked with a CSV delay.
+type CsvSpendableOutput interface {
+	SpendableOutput
+
+	// ConfHeight returns the height at which this output was confirmed.
+	// A zero value indicates that the output has not been confirmed.
+	ConfHeight() uint32
+
+	// SetConfHeight marks the height at which the output is confirmed in
+	// the chain.
+	SetConfHeight(height uint32)
+
+	// BlocksToMaturity returns the relative timelock, as a number of
+	// blocks, that must be built on top of the confirmation height before
+	// the output can be spent.
+	BlocksToMaturity() uint32
+
+	// OriginChanPoint returns the outpoint of the channel from which this
+	// output is derived.
+	OriginChanPoint() *wire.OutPoint
+}

utxonursery.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
+	"github.com/lightningnetwork/lnd/sweep"
 	"io"
 	"sync"
 	"sync/atomic"
@@ -953,14 +954,14 @@ func (u *utxoNursery) createSweepTx(kgtnOutputs []kidOutput,
 	// outputs are CLTV locked outputs that have had their timelocks
 	// expire.
 	var (
-		csvOutputs     []CsvSpendableOutput
+		csvOutputs     []sweep.CsvSpendableOutput
-		cltvOutputs    []SpendableOutput
+		cltvOutputs    []sweep.SpendableOutput
 		weightEstimate lnwallet.TxWeightEstimator
 	)
 
 	// Allocate enough room for both types of kindergarten outputs.
-	csvOutputs = make([]CsvSpendableOutput, 0, len(kgtnOutputs))
+	csvOutputs = make([]sweep.CsvSpendableOutput, 0, len(kgtnOutputs))
-	cltvOutputs = make([]SpendableOutput, 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.
@@ -1028,8 +1029,8 @@ func (u *utxoNursery) createSweepTx(kgtnOutputs []kidOutput,
 // 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 []CsvSpendableOutput,
+	csvInputs []sweep.CsvSpendableOutput,
-	cltvInputs []SpendableOutput) (*wire.MsgTx, error) {
+	cltvInputs []sweep.SpendableOutput) (*wire.MsgTx, error) {
 
 	// Generate the receiving script to which the funds will be swept.
 	pkScript, err := u.cfg.GenSweepScript()
@@ -1099,7 +1100,7 @@ func (u *utxoNursery) populateSweepTx(txWeight int64, classHeight uint32,
 
 	// 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 {
+	addWitness := func(idx int, tso sweep.SpendableOutput) error {
 		witness, err := tso.BuildWitness(
 			u.cfg.Signer, sweepTx, hashCache, idx,
 		)
@@ -1635,29 +1636,6 @@ func newSweepPkScript(wallet lnwallet.WalletController) ([]byte, error) {
 	return txscript.PayToAddrScript(sweepAddr)
 }
 
-// CsvSpendableOutput is a SpendableOutput that contains all of the information
-// necessary to construct, sign, and sweep an output locked with a CSV delay.
-type CsvSpendableOutput interface {
-	SpendableOutput
-
-	// ConfHeight returns the height at which this output was confirmed.
-	// A zero value indicates that the output has not been confirmed.
-	ConfHeight() uint32
-
-	// SetConfHeight marks the height at which the output is confirmed in
-	// the chain.
-	SetConfHeight(height uint32)
-
-	// BlocksToMaturity returns the relative timelock, as a number of
-	// blocks, that must be built on top of the confirmation height before
-	// the output can be spent.
-	BlocksToMaturity() uint32
-
-	// OriginChanPoint returns the outpoint of the channel from which this
-	// output is derived.
-	OriginChanPoint() *wire.OutPoint
-}
-
 // babyOutput represents a two-stage CSV locked output, and is used to track
 // htlc outputs through incubation. The first stage requires broadcasting a
 // presigned timeout txn that spends from the CLTV locked output on the
@@ -1971,5 +1949,5 @@ func readTxOut(r io.Reader, txo *wire.TxOut) error {
 
 // Compile-time constraint to ensure kidOutput and babyOutput implement the
 // CsvSpendableOutput interface.
-var _ CsvSpendableOutput = (*kidOutput)(nil)
+var _ sweep.CsvSpendableOutput = (*kidOutput)(nil)
-var _ CsvSpendableOutput = (*babyOutput)(nil)
+var _ sweep.CsvSpendableOutput = (*babyOutput)(nil)