mirror of https://github.com/guggero/chantools
Add sweeptimelock command
Oliver Gugger
4 years ago
parent
a2114a28f4
commit
5034c6bab6
@ -0,0 +1,89 @@
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package chantools
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import (
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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/hdkeychain"
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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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type signer struct {
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extendedKey *hdkeychain.ExtendedKey
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}
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func (s *signer) SignOutputRaw(tx *wire.MsgTx,
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signDesc *input.SignDescriptor) ([]byte, error) {
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witnessScript := signDesc.WitnessScript
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// First attempt to fetch the private key which corresponds to the
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// specified public key.
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privKey, err := s.fetchPrivKey(&signDesc.KeyDesc)
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if err != nil {
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return nil, err
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}
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privKey, err = maybeTweakPrivKey(signDesc, privKey)
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if err != nil {
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return nil, err
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}
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amt := signDesc.Output.Value
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sig, err := txscript.RawTxInWitnessSignature(
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tx, signDesc.SigHashes, signDesc.InputIndex, amt,
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witnessScript, signDesc.HashType, privKey,
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)
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if err != nil {
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return nil, err
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}
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// Chop off the sighash flag at the end of the signature.
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return sig[:len(sig)-1], nil
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}
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func (s *signer) ComputeInputScript(tx *wire.MsgTx,
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signDesc *input.SignDescriptor) (*input.Script, error) {
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return nil, fmt.Errorf("unimplemented")
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}
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func (s *signer) fetchPrivKey(descriptor *keychain.KeyDescriptor) (
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*btcec.PrivateKey, error) {
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key, err := deriveChildren(s.extendedKey, []uint32{
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hardenedKeyStart + uint32(keychain.BIP0043Purpose),
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hardenedKeyStart + chainParams.HDCoinType,
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hardenedKeyStart + uint32(descriptor.Family),
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0,
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descriptor.Index,
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})
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if err != nil {
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return nil, err
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}
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return key.ECPrivKey()
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}
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// maybeTweakPrivKey examines the single and double tweak parameters on the
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// passed sign descriptor and may perform a mapping on the passed private key
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// in order to utilize the tweaks, if populated.
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func maybeTweakPrivKey(signDesc *input.SignDescriptor,
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privKey *btcec.PrivateKey) (*btcec.PrivateKey, error) {
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var retPriv *btcec.PrivateKey
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switch {
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case signDesc.SingleTweak != nil:
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retPriv = input.TweakPrivKey(privKey,
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signDesc.SingleTweak)
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case signDesc.DoubleTweak != nil:
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retPriv = input.DeriveRevocationPrivKey(privKey,
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signDesc.DoubleTweak)
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default:
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retPriv = privKey
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}
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return retPriv, nil
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}
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@ -0,0 +1,234 @@
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package chantools
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import (
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"bytes"
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"encoding/hex"
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"fmt"
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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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/hdkeychain"
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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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const (
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maxCsvTimeout = 15000
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feeSatPerByte = 3
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)
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func sweepTimeLock(cfg *config, entries []*SummaryEntry, sweepAddr string,
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publish bool) error {
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extendedKey, err := hdkeychain.NewKeyFromString(cfg.RootKey)
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if err != nil {
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return err
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}
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signer := &signer{extendedKey: extendedKey}
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sweepTx := wire.NewMsgTx(2)
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entryIndex := 0
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value := int64(0)
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signDescs := make([]*input.SignDescriptor, 0)
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for _, entry := range entries {
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if entry.ClosingTX == nil || entry.ForceClose == nil ||
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entry.ClosingTX.AllOutsSpent || entry.LocalBalance == 0 {
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log.Infof("Not sweeping %s, info missing or all spent",
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entry.ChannelPoint)
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continue
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}
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fc := entry.ForceClose
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txindex := -1
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if len(fc.Outs) == 1 {
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txindex = 0
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if fc.Outs[0].Value != entry.LocalBalance {
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log.Errorf("Potential value mismatch! %d vs %d (%s)",
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fc.Outs[0].Value, entry.LocalBalance,
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entry.ChannelPoint)
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}
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} else {
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for idx, out := range fc.Outs {
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if out.Value == entry.LocalBalance {
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txindex = idx
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}
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}
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}
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if txindex == -1 {
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log.Errorf("Could not find sweep output for chan %s",
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entry.ChannelPoint)
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continue
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}
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txHash, err := chainhash.NewHashFromStr(fc.TXID)
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if err != nil {
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return fmt.Errorf("error parsing tx hash: %v", err)
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}
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commitPointBytes, err := hex.DecodeString(fc.CommitPoint)
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if err != nil {
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return fmt.Errorf("error parsing commit point: %v", err)
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}
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commitPoint, err := btcec.ParsePubKey(commitPointBytes, btcec.S256())
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if err != nil {
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return fmt.Errorf("error parsing commit point: %v", err)
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}
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revPointBytes, err := hex.DecodeString(fc.RevocationBasepoint.Pubkey)
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if err != nil {
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return fmt.Errorf("error parsing commit point: %v", err)
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}
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revPoint, err := btcec.ParsePubKey(revPointBytes, btcec.S256())
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if err != nil {
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return fmt.Errorf("error parsing commit point: %v", err)
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}
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delayKeyDesc := &keychain.KeyDescriptor{
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KeyLocator: keychain.KeyLocator{
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Family: keychain.KeyFamily(fc.DelayBasepoint.Family),
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Index: fc.DelayBasepoint.Index,
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},
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}
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delayPrivkey, err := signer.fetchPrivKey(delayKeyDesc)
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if err != nil {
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return fmt.Errorf("error getting private key: %v", err)
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}
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delayKey := input.TweakPubKey(delayPrivkey.PubKey(), commitPoint)
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revocationKey := input.DeriveRevocationPubkey(
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revPoint, commitPoint,
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)
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var (
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csvTimeout = int32(-1)
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script []byte
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scriptHash []byte
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)
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targetScript, err := hex.DecodeString(fc.Outs[txindex].Script)
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if err != nil {
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return fmt.Errorf("error parsing target script: %v", err)
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}
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if len(targetScript) != 34 {
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log.Errorf("invalid target script: %x", targetScript)
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continue
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}
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for i := 0; csvTimeout == -1 && i < maxCsvTimeout; i++ {
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s, err := input.CommitScriptToSelf(
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uint32(i), delayKey, revocationKey,
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)
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if err != nil {
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return fmt.Errorf("error creating script: %v", err)
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}
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sh, err := input.WitnessScriptHash(s)
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if err != nil {
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return fmt.Errorf("error hashing script: %v", err)
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}
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if bytes.Equal(targetScript[0:8], sh[0:8]) {
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csvTimeout = int32(i)
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script = s
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scriptHash = sh
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}
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}
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if csvTimeout == -1 || len(script) == 0 {
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log.Errorf("Could not create matching script for %s " +
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"or csv too high: %d", entry.ChannelPoint,
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csvTimeout)
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continue
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}
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sweepTx.TxIn = append(sweepTx.TxIn, &wire.TxIn{
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PreviousOutPoint: wire.OutPoint{
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Hash: *txHash,
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Index: uint32(txindex),
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},
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SignatureScript: nil,
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Witness: nil,
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Sequence: input.LockTimeToSequence(
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false, uint32(csvTimeout),
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),
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})
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singleTweak := input.SingleTweakBytes(
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commitPoint, delayPrivkey.PubKey(),
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)
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signDesc := &input.SignDescriptor{
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KeyDesc: *delayKeyDesc,
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SingleTweak: singleTweak,
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WitnessScript: script,
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Output: &wire.TxOut{
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PkScript: scriptHash,
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Value: int64(fc.Outs[txindex].Value),
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},
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HashType: txscript.SigHashAll,
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InputIndex: entryIndex,
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}
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value += int64(fc.Outs[txindex].Value)
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signDescs = append(signDescs, signDesc)
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entryIndex++
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}
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if len(signDescs) != len(sweepTx.TxIn) {
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return fmt.Errorf("length mismatch")
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}
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sweepScript, err := pkhScript(sweepAddr)
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if err != nil {
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return err
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}
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sweepTx.TxOut = []*wire.TxOut{{
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Value: value,
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PkScript: sweepScript,
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}}
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sigHashes := txscript.NewTxSigHashes(sweepTx)
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for idx, desc := range signDescs {
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desc.SigHashes = sigHashes
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witness, err := input.CommitSpendTimeout(signer, desc, sweepTx)
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if err != nil {
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return err
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}
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sweepTx.TxIn[idx].Witness = witness
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}
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size := sweepTx.SerializeSize()
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fee := int64(size*feeSatPerByte)
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sweepTx.TxOut[0].Value = value - fee
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// Sign again after output fixing.
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sigHashes = txscript.NewTxSigHashes(sweepTx)
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for idx, desc := range signDescs {
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desc.SigHashes = sigHashes
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witness, err := input.CommitSpendTimeout(signer, desc, sweepTx)
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if err != nil {
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return err
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}
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sweepTx.TxIn[idx].Witness = witness
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}
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var buf bytes.Buffer
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err = sweepTx.Serialize(&buf)
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if err != nil {
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return err
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}
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log.Infof("Fee %d sats of %d total amount (for size %d)",
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fee, value, sweepTx.SerializeSize())
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log.Infof("Transaction: %x", buf.Bytes())
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return nil
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}
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func pkhScript(addr string) ([]byte, error) {
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targetPubKeyHash, err := parseAddr(addr)
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if err != nil {
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return nil, err
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}
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builder := txscript.NewScriptBuilder()
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builder.AddOp(txscript.OP_0)
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builder.AddData(targetPubKeyHash)
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return builder.Script()
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}
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