mirror of https://github.com/guggero/chantools
multi: add new pullanchor command
Oliver Gugger
5 months ago
parent
c89cede963
commit
7227c7f101
@ -0,0 +1,511 @@
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package main
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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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"math"
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"github.com/btcsuite/btcd/btcutil"
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"github.com/btcsuite/btcd/btcutil/hdkeychain"
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"github.com/btcsuite/btcd/btcutil/psbt"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/mempool"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/lightninglabs/chantools/btc"
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"github.com/lightninglabs/chantools/lnd"
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"github.com/lightningnetwork/lnd/input"
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"github.com/lightningnetwork/lnd/keychain"
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"github.com/lightningnetwork/lnd/lnwallet/chainfee"
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"github.com/spf13/cobra"
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)
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type pullAnchorCommand struct {
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APIURL string
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SponsorInput string
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AnchorAddrs []string
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ChangeAddr string
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FeeRate uint32
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rootKey *rootKey
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cmd *cobra.Command
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}
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func newPullAnchorCommand() *cobra.Command {
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cc := &pullAnchorCommand{}
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cc.cmd = &cobra.Command{
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Use: "pullanchor",
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Short: "Attempt to CPFP an anchor output of a channel",
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Long: `Use this command to confirm a channel force close
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transaction of an anchor output channel type. This will attempt to CPFP the
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330 byte anchor output created for your node.`,
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Example: `chantools pullanchor \
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--sponsorinput txid:vout \
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--anchoraddr bc1q..... \
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--changeaddr bc1q..... \
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--feerate 30`,
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RunE: cc.Execute,
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}
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cc.cmd.Flags().StringVar(
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&cc.APIURL, "apiurl", defaultAPIURL, "API URL to use (must "+
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"be esplora compatible)",
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)
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cc.cmd.Flags().StringVar(
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&cc.SponsorInput, "sponsorinput", "", "the input to use to "+
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"sponsor the CPFP transaction; must be owned by the "+
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"lnd node that owns the anchor output",
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)
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cc.cmd.Flags().StringArrayVar(
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&cc.AnchorAddrs, "anchoraddr", nil, "the address of the "+
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"anchor output (p2wsh or p2tr output with 330 "+
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"satoshis) that should be pulled; can be specified "+
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"multiple times per command to pull multiple anchors "+
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"with a single transaction",
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)
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cc.cmd.Flags().StringVar(
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&cc.ChangeAddr, "changeaddr", "", "the change address to "+
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"send the remaining funds to",
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)
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cc.cmd.Flags().Uint32Var(
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&cc.FeeRate, "feerate", defaultFeeSatPerVByte, "fee rate to "+
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"use for the sweep transaction in sat/vByte",
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)
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cc.rootKey = newRootKey(cc.cmd, "deriving keys")
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return cc.cmd
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}
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func (c *pullAnchorCommand) Execute(_ *cobra.Command, _ []string) error {
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extendedKey, err := c.rootKey.read()
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if err != nil {
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return fmt.Errorf("error reading root key: %w", err)
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}
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// Make sure all input is provided.
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if c.SponsorInput == "" {
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return fmt.Errorf("sponsor input is required")
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}
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if len(c.AnchorAddrs) == 0 {
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return fmt.Errorf("at least one anchor addr is required")
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}
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if c.ChangeAddr == "" {
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return fmt.Errorf("change addr is required")
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}
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outpoint, err := lnd.ParseOutpoint(c.SponsorInput)
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if err != nil {
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return fmt.Errorf("error parsing sponsor input outpoint: %w",
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err)
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}
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changeScript, err := lnd.GetP2WPKHScript(c.ChangeAddr, chainParams)
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if err != nil {
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return fmt.Errorf("error parsing change addr: %w", err)
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}
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// Set default values.
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if c.FeeRate == 0 {
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c.FeeRate = defaultFeeSatPerVByte
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}
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return createPullTransactionTemplate(
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extendedKey, c.APIURL, outpoint, c.AnchorAddrs, changeScript,
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c.FeeRate,
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)
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}
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type targetAnchor struct {
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addr string
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keyDesc *keychain.KeyDescriptor
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outpoint wire.OutPoint
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utxo *wire.TxOut
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script []byte
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scriptTree *input.AnchorScriptTree
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}
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func createPullTransactionTemplate(rootKey *hdkeychain.ExtendedKey,
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apiURL string, sponsorOutpoint *wire.OutPoint, anchorAddrs []string,
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changeScript []byte, feeRate uint32) error {
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signer := &lnd.Signer{
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ExtendedKey: rootKey,
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ChainParams: chainParams,
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}
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api := &btc.ExplorerAPI{BaseURL: apiURL}
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estimator := input.TxWeightEstimator{}
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// Make sure the sponsor input is a P2WPKH or P2TR input and is known
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// to the block explorer, so we can fetch the witness utxo.
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sponsorTx, err := api.Transaction(sponsorOutpoint.Hash.String())
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if err != nil {
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return fmt.Errorf("error fetching sponsor tx: %w", err)
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}
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sponsorTxOut := sponsorTx.Vout[sponsorOutpoint.Index]
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sponsorPkScript, err := hex.DecodeString(sponsorTxOut.ScriptPubkey)
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if err != nil {
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return fmt.Errorf("error decoding sponsor pkscript: %w", err)
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}
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sponsorType, err := txscript.ParsePkScript(sponsorPkScript)
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if err != nil {
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return fmt.Errorf("error parsing sponsor pkscript: %w", err)
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}
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var sponsorSigHashType txscript.SigHashType
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switch sponsorType.Class() {
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case txscript.WitnessV0PubKeyHashTy:
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estimator.AddP2WKHInput()
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sponsorSigHashType = txscript.SigHashAll
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case txscript.WitnessV1TaprootTy:
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sponsorSigHashType = txscript.SigHashDefault
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estimator.AddTaprootKeySpendInput(sponsorSigHashType)
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default:
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return fmt.Errorf("unsupported sponsor input type: %v",
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sponsorType.Class())
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}
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tx := wire.NewMsgTx(2)
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packet, err := psbt.NewFromUnsignedTx(tx)
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if err != nil {
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return fmt.Errorf("error creating PSBT: %w", err)
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}
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// Let's add the sponsor input to the PSBT.
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sponsorUtxo := &wire.TxOut{
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Value: int64(sponsorTxOut.Value),
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PkScript: sponsorPkScript,
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}
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packet.UnsignedTx.TxIn = append(packet.UnsignedTx.TxIn, &wire.TxIn{
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PreviousOutPoint: *sponsorOutpoint,
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Sequence: mempool.MaxRBFSequence,
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})
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packet.Inputs = append(packet.Inputs, psbt.PInput{
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WitnessUtxo: sponsorUtxo,
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SighashType: sponsorSigHashType,
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})
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targets, err := addAnchorInputs(
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anchorAddrs, packet, api, &estimator, rootKey,
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)
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if err != nil {
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return fmt.Errorf("error adding anchor inputs: %w", err)
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}
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// Now we can calculate the fee and add the change output.
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estimator.AddP2WKHOutput()
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totalOutputValue := btcutil.Amount(sponsorTxOut.Value + 330)
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feeRateKWeight := chainfee.SatPerKVByte(1000 * feeRate).FeePerKWeight()
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totalFee := feeRateKWeight.FeeForWeight(int64(estimator.Weight()))
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log.Infof("Fee %d sats of %d total amount (estimated weight %d)",
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totalFee, totalOutputValue, estimator.Weight())
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packet.UnsignedTx.TxOut = append(packet.UnsignedTx.TxOut, &wire.TxOut{
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Value: int64(totalOutputValue - totalFee),
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PkScript: changeScript,
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})
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packet.Outputs = append(packet.Outputs, psbt.POutput{})
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prevOutFetcher := txscript.NewMultiPrevOutFetcher(
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map[wire.OutPoint]*wire.TxOut{
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*sponsorOutpoint: sponsorUtxo,
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},
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)
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for idx := range targets {
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prevOutFetcher.AddPrevOut(
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targets[idx].outpoint, targets[idx].utxo,
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)
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}
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// And now we sign the anchor inputs.
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for idx := range targets {
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target := targets[idx]
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signDesc := &input.SignDescriptor{
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KeyDesc: *target.keyDesc,
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WitnessScript: target.script,
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Output: target.utxo,
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PrevOutputFetcher: prevOutFetcher,
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InputIndex: idx + 1,
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}
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var anchorWitness wire.TxWitness
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switch {
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// Simple Taproot Channel:
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case target.scriptTree != nil:
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signDesc.SignMethod = input.TaprootKeySpendSignMethod
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signDesc.HashType = txscript.SigHashDefault
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signDesc.TapTweak = target.scriptTree.TapscriptRoot
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anchorSig, err := signer.SignOutputRaw(
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packet.UnsignedTx, signDesc,
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)
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if err != nil {
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return fmt.Errorf("error signing anchor "+
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"input: %w", err)
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}
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anchorWitness = wire.TxWitness{
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anchorSig.Serialize(),
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}
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// Anchor Channel:
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default:
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signDesc.SignMethod = input.WitnessV0SignMethod
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signDesc.HashType = txscript.SigHashAll
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anchorSig, err := signer.SignOutputRaw(
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packet.UnsignedTx, signDesc,
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)
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if err != nil {
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return fmt.Errorf("error signing anchor "+
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"input: %w", err)
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}
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anchorWitness = make(wire.TxWitness, 2)
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anchorWitness[0] = append(
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anchorSig.Serialize(),
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byte(txscript.SigHashAll),
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)
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anchorWitness[1] = target.script
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}
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var witnessBuf bytes.Buffer
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err = psbt.WriteTxWitness(&witnessBuf, anchorWitness)
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if err != nil {
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return fmt.Errorf("error serializing witness: %w", err)
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}
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packet.Inputs[idx+1].FinalScriptWitness = witnessBuf.Bytes()
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}
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packetBase64, err := packet.B64Encode()
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if err != nil {
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return fmt.Errorf("error encoding PSBT: %w", err)
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}
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log.Infof("Prepared PSBT follows, please now call\n" +
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"'lncli wallet psbt finalize <psbt>' to finalize the\n" +
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"transaction, then publish it manually or by using\n" +
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"'lncli wallet publishtx <final_tx>':\n\n" + packetBase64 +
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"\n")
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return nil
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}
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func addAnchorInputs(anchorAddrs []string, packet *psbt.Packet,
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api *btc.ExplorerAPI, estimator *input.TxWeightEstimator,
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rootKey *hdkeychain.ExtendedKey) ([]targetAnchor, error) {
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// Fetch the additional info we need for the anchor output as well.
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results := make([]targetAnchor, len(anchorAddrs))
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for idx, anchorAddr := range anchorAddrs {
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anchorTx, anchorIndex, err := api.Outpoint(anchorAddr)
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if err != nil {
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return nil, fmt.Errorf("error fetching anchor "+
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"outpoint: %w", err)
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}
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anchorTxHash, err := chainhash.NewHashFromStr(anchorTx.TXID)
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if err != nil {
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return nil, fmt.Errorf("error decoding anchor txid: %w",
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err)
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}
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addr, err := btcutil.DecodeAddress(anchorAddr, chainParams)
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if err != nil {
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return nil, fmt.Errorf("error decoding address: %w",
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err)
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}
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anchorPkScript, err := txscript.PayToAddrScript(addr)
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if err != nil {
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return nil, fmt.Errorf("error creating pk script: %w",
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err)
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}
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target := targetAnchor{
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addr: anchorAddr,
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utxo: &wire.TxOut{
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Value: 330,
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PkScript: anchorPkScript,
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},
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outpoint: wire.OutPoint{
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Hash: *anchorTxHash,
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Index: uint32(anchorIndex),
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},
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}
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switch addr.(type) {
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case *btcutil.AddressWitnessScriptHash:
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estimator.AddWitnessInput(input.AnchorWitnessSize)
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anchorKeyDesc, anchorWitnessScript, err := findAnchorKey(
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rootKey, anchorPkScript,
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)
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if err != nil {
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return nil, fmt.Errorf("could not find "+
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"key for anchor address %v: %w",
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anchorAddr, err)
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}
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target.keyDesc = anchorKeyDesc
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target.script = anchorWitnessScript
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case *btcutil.AddressTaproot:
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estimator.AddTaprootKeySpendInput(
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txscript.SigHashDefault,
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)
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anchorKeyDesc, scriptTree, err := findTaprootAnchorKey(
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rootKey, anchorPkScript,
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)
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if err != nil {
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return nil, fmt.Errorf("could not find "+
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"key for anchor address %v: %w",
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anchorAddr, err)
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}
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target.keyDesc = anchorKeyDesc
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target.scriptTree = scriptTree
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default:
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return nil, fmt.Errorf("unsupported address type: %T",
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addr)
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}
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log.Infof("Found multisig key %x for anchor pk script %x",
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target.keyDesc.PubKey.SerializeCompressed(),
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anchorPkScript)
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packet.UnsignedTx.TxIn = append(
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packet.UnsignedTx.TxIn, &wire.TxIn{
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PreviousOutPoint: target.outpoint,
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Sequence: mempool.MaxRBFSequence,
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},
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)
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packet.Inputs = append(packet.Inputs, psbt.PInput{
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WitnessUtxo: target.utxo,
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WitnessScript: target.script,
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})
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results[idx] = target
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}
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return results, nil
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}
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func findAnchorKey(rootKey *hdkeychain.ExtendedKey,
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targetScript []byte) (*keychain.KeyDescriptor, []byte, error) {
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family := keychain.KeyFamilyMultiSig
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localMultisig, err := lnd.DeriveChildren(rootKey, []uint32{
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lnd.HardenedKeyStart + uint32(keychain.BIP0043Purpose),
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lnd.HardenedKeyStart + chainParams.HDCoinType,
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lnd.HardenedKeyStart + uint32(family),
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0,
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})
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if err != nil {
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return nil, nil, fmt.Errorf("could not derive local "+
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"multisig key: %w", err)
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}
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// Loop through the local multisig keys to find the target anchor
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// script.
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for index := uint32(0); index < math.MaxInt16; index++ {
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currentKey, err := localMultisig.DeriveNonStandard(index)
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving child "+
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"key: %w", err)
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}
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currentPubkey, err := currentKey.ECPubKey()
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving public "+
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"key: %w", err)
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}
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script, err := input.CommitScriptAnchor(currentPubkey)
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving script: "+
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"%w", err)
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}
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pkScript, err := input.WitnessScriptHash(script)
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving script "+
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"hash: %w", err)
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}
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if !bytes.Equal(pkScript, targetScript) {
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continue
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}
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return &keychain.KeyDescriptor{
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PubKey: currentPubkey,
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KeyLocator: keychain.KeyLocator{
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Family: family,
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Index: index,
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},
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}, script, nil
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}
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return nil, nil, fmt.Errorf("no matching pubkeys found")
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}
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func findTaprootAnchorKey(rootKey *hdkeychain.ExtendedKey,
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targetScript []byte) (*keychain.KeyDescriptor, *input.AnchorScriptTree,
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error) {
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family := keychain.KeyFamilyPaymentBase
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localPayment, err := lnd.DeriveChildren(rootKey, []uint32{
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lnd.HardenedKeyStart + uint32(keychain.BIP0043Purpose),
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lnd.HardenedKeyStart + chainParams.HDCoinType,
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lnd.HardenedKeyStart + uint32(family),
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0,
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})
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if err != nil {
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return nil, nil, fmt.Errorf("could not derive local "+
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"multisig key: %w", err)
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}
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// Loop through the local multisig keys to find the target anchor
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// script.
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for index := uint32(0); index < math.MaxInt16; index++ {
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currentKey, err := localPayment.DeriveNonStandard(index)
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving child "+
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"key: %w", err)
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}
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currentPubkey, err := currentKey.ECPubKey()
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving public "+
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"key: %w", err)
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}
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scriptTree, err := input.NewAnchorScriptTree(currentPubkey)
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if err != nil {
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return nil, nil, fmt.Errorf("error deriving taproot "+
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"key: %w", err)
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}
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||||
|
||||
pkScript, err := input.PayToTaprootScript(scriptTree.TaprootKey)
|
||||
if err != nil {
|
||||
return nil, nil, fmt.Errorf("error deriving pk "+
|
||||
"script: %w", err)
|
||||
}
|
||||
if !bytes.Equal(pkScript, targetScript) {
|
||||
continue
|
||||
}
|
||||
|
||||
return &keychain.KeyDescriptor{
|
||||
PubKey: currentPubkey,
|
||||
KeyLocator: keychain.KeyLocator{
|
||||
Family: family,
|
||||
Index: index,
|
||||
},
|
||||
}, scriptTree, nil
|
||||
}
|
||||
|
||||
return nil, nil, fmt.Errorf("no matching pubkeys found")
|
||||
}
|
||||
@ -0,0 +1,49 @@
|
||||
## chantools pullanchor
|
||||
|
||||
Attempt to CPFP an anchor output of a channel
|
||||
|
||||
### Synopsis
|
||||
|
||||
Use this command to confirm a channel force close
|
||||
transaction of an anchor output channel type. This will attempt to CPFP the
|
||||
330 byte anchor output created for your node.
|
||||
|
||||
```
|
||||
chantools pullanchor [flags]
|
||||
```
|
||||
|
||||
### Examples
|
||||
|
||||
```
|
||||
chantools pullanchor \
|
||||
--sponsorinput txid:vout \
|
||||
--anchoraddr bc1q..... \
|
||||
--changeaddr bc1q..... \
|
||||
--feerate 30
|
||||
```
|
||||
|
||||
### Options
|
||||
|
||||
```
|
||||
--anchoraddr string the address of the anchor output (p2wsh output with 330 satoshis)
|
||||
--apiurl string API URL to use (must be esplora compatible) (default "https://blockstream.info/api")
|
||||
--bip39 read a classic BIP39 seed and passphrase from the terminal instead of asking for lnd seed format or providing the --rootkey flag
|
||||
--changeaddr string the change address to send the remaining funds to
|
||||
--feerate uint32 fee rate to use for the sweep transaction in sat/vByte (default 30)
|
||||
-h, --help help for pullanchor
|
||||
--rootkey string BIP32 HD root key of the wallet to use for deriving keys; leave empty to prompt for lnd 24 word aezeed
|
||||
--sponsorinput string the input to use to sponsor the CPFP transaction; must be owned by the lnd node that owns the anchor output
|
||||
```
|
||||
|
||||
### Options inherited from parent commands
|
||||
|
||||
```
|
||||
-r, --regtest Indicates if regtest parameters should be used
|
||||
-s, --signet Indicates if the public signet parameters should be used
|
||||
-t, --testnet Indicates if testnet parameters should be used
|
||||
```
|
||||
|
||||
### SEE ALSO
|
||||
|
||||
* [chantools](chantools.md) - Chantools helps recover funds from lightning channels
|
||||
|
||||
Loading…
Reference in New Issue