mirror of
https://github.com/lightninglabs/loop
synced 2024-11-04 06:00:21 +00:00
111 lines
2.6 KiB
Go
111 lines
2.6 KiB
Go
package sweep
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import (
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"context"
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"fmt"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil"
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"github.com/lightninglabs/loop/lndclient"
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"github.com/lightninglabs/loop/swap"
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"github.com/lightningnetwork/lnd/input"
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"github.com/lightningnetwork/lnd/keychain"
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)
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// Sweeper creates htlc sweep txes.
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type Sweeper struct {
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Lnd *lndclient.LndServices
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}
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// CreateSweepTx creates an htlc sweep tx.
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func (s *Sweeper) CreateSweepTx(
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globalCtx context.Context, height int32,
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htlc *swap.Htlc, htlcOutpoint wire.OutPoint,
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keyBytes [33]byte,
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witnessFunc func(sig []byte) (wire.TxWitness, error),
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amount, fee btcutil.Amount,
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destAddr btcutil.Address) (*wire.MsgTx, error) {
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// Compose tx.
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sweepTx := wire.NewMsgTx(2)
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sweepTx.LockTime = uint32(height)
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// Add HTLC input.
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sweepTx.AddTxIn(&wire.TxIn{
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PreviousOutPoint: htlcOutpoint,
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SignatureScript: htlc.SigScript,
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})
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// Add output for the destination address.
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sweepPkScript, err := txscript.PayToAddrScript(destAddr)
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if err != nil {
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return nil, err
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}
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sweepTx.AddTxOut(&wire.TxOut{
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PkScript: sweepPkScript,
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Value: int64(amount - fee),
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})
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// Generate a signature for the swap htlc transaction.
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key, err := btcec.ParsePubKey(keyBytes[:], btcec.S256())
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if err != nil {
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return nil, err
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}
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signDesc := input.SignDescriptor{
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WitnessScript: htlc.Script,
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Output: &wire.TxOut{
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Value: int64(amount),
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},
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HashType: txscript.SigHashAll,
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InputIndex: 0,
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KeyDesc: keychain.KeyDescriptor{
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PubKey: key,
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},
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}
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rawSigs, err := s.Lnd.Signer.SignOutputRaw(
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globalCtx, sweepTx, []*input.SignDescriptor{&signDesc},
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)
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if err != nil {
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return nil, fmt.Errorf("signing: %v", err)
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}
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sig := rawSigs[0]
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// Add witness stack to the tx input.
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sweepTx.TxIn[0].Witness, err = witnessFunc(sig)
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if err != nil {
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return nil, err
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}
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return sweepTx, nil
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}
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// GetSweepFee calculates the required tx fee to spend to P2WKH. It takes a
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// function that is expected to add the weight of the input to the weight
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// estimator.
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func (s *Sweeper) GetSweepFee(ctx context.Context,
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addInputEstimate func(*input.TxWeightEstimator),
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sweepConfTarget int32) (
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btcutil.Amount, error) {
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// Get fee estimate from lnd.
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feeRate, err := s.Lnd.WalletKit.EstimateFee(ctx, sweepConfTarget)
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if err != nil {
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return 0, fmt.Errorf("estimate fee: %v", err)
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}
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// Calculate weight for this tx.
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var weightEstimate input.TxWeightEstimator
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weightEstimate.AddP2WKHOutput()
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addInputEstimate(&weightEstimate)
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weight := weightEstimate.Weight()
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return feeRate.FeeForWeight(int64(weight)), nil
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}
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