lnwallet: Use TxWeightEstimator for funding transaction.
This commit is contained in:
Jim Posen
Olaoluwa Osuntokun
parent
fb32c3f73d
commit
ced530f98e
@ -504,13 +504,13 @@ func (l *LightningWallet) handleFundingReserveRequest(req *initFundingReserveMsg
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// don't need to perform any coin selection. Otherwise, attempt to
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// obtain enough coins to meet the required funding amount.
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if req.fundingAmount != 0 {
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// Coin selection is done on the basis of sat-per-byte, so
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// Coin selection is done on the basis of sat-per-weight, so
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// we'll query the fee estimator for a fee to use to ensure the
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// funding transaction gets into the _next_ block.
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//
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// TODO(roasbeef): shouldn't be targeting next block
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satPerByte := l.Cfg.FeeEstimator.EstimateFeePerByte(1)
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err := l.selectCoinsAndChange(satPerByte, req.fundingAmount,
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satPerWeight := l.Cfg.FeeEstimator.EstimateFeePerWeight(1)
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err := l.selectCoinsAndChange(satPerWeight, req.fundingAmount,
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reservation.ourContribution)
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if err != nil {
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req.err <- err
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@ -1039,20 +1039,19 @@ func (l *LightningWallet) handleFundingCounterPartySigs(msg *addCounterPartySigs
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// Next, create the spending scriptSig, and then verify that the script
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// is complete, allowing us to spend from the funding transaction.
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theirCommitSig := msg.theirCommitmentSig
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channelValue := int64(res.partialState.Capacity)
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hashCache := txscript.NewTxSigHashes(&commitTx)
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sigHash, err := txscript.CalcWitnessSigHash(witnessScript, hashCache,
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txscript.SigHashAll, &commitTx, 0, channelValue)
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if err != nil {
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msg.err <- fmt.Errorf("counterparty's commitment signature is "+
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"invalid: %v", err)
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msg.err <- err
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msg.completeChan <- nil
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return
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}
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// Verify that we've received a valid signature from the remote party
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// for our version of the commitment transaction.
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theirCommitSig := msg.theirCommitmentSig
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sig, err := btcec.ParseSignature(theirCommitSig, btcec.S256())
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if err != nil {
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msg.err <- err
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@ -1268,8 +1267,8 @@ func (l *LightningWallet) handleSingleFunderSigs(req *addSingleFunderSigsMsg) {
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// within the passed contribution's inputs. If necessary, a change address will
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// also be generated.
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// TODO(roasbeef): remove hardcoded fees and req'd confs for outputs.
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func (l *LightningWallet) selectCoinsAndChange(feeRate uint64, amt btcutil.Amount,
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contribution *ChannelContribution) error {
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func (l *LightningWallet) selectCoinsAndChange(feeRatePerWeight uint64,
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amt btcutil.Amount, contribution *ChannelContribution) error {
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// We hold the coin select mutex while querying for outputs, and
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// performing coin selection in order to avoid inadvertent double
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@ -1277,8 +1276,8 @@ func (l *LightningWallet) selectCoinsAndChange(feeRate uint64, amt btcutil.Amoun
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l.coinSelectMtx.Lock()
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defer l.coinSelectMtx.Unlock()
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walletLog.Infof("Performing coin selection using %v sat/byte as fee "+
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"rate", feeRate)
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walletLog.Infof("Performing coin selection using %v sat/weight as fee "+
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"rate", feeRatePerWeight)
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// Find all unlocked unspent witness outputs with greater than 1
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// confirmation.
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@ -1291,7 +1290,7 @@ func (l *LightningWallet) selectCoinsAndChange(feeRate uint64, amt btcutil.Amoun
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// Perform coin selection over our available, unlocked unspent outputs
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// in order to find enough coins to meet the funding amount
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// requirements.
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selectedCoins, changeAmt, err := coinSelect(feeRate, amt, coins)
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selectedCoins, changeAmt, err := coinSelect(feeRatePerWeight, amt, coins)
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if err != nil {
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return err
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}
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@ -1419,33 +1418,9 @@ func selectInputs(amt btcutil.Amount, coins []*Utxo) (btcutil.Amount, []*wire.Ou
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// change output to fund amt satoshis, adhering to the specified fee rate. The
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// specified fee rate should be expressed in sat/byte for coin selection to
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// function properly.
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func coinSelect(feeRate uint64, amt btcutil.Amount,
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func coinSelect(feeRatePerWeight uint64, amt btcutil.Amount,
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coins []*Utxo) ([]*wire.OutPoint, btcutil.Amount, error) {
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const (
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// txOverhead is the overhead of a transaction residing within
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// the version number and lock time.
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txOverhead = 8
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// p2wkhSpendSize an estimate of the number of bytes it takes
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// to spend a p2wkh output.
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//
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// (p2wkh witness) + txid + index + varint script size + sequence
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// TODO(roasbeef): div by 3 due to witness size?
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p2wkhSpendSize = (1 + 73 + 1 + 33) + 32 + 4 + 1 + 4
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// p2wkhOutputSize is an estimate of the size of a regualr
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// p2wkh output.
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//
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// 8 (output) + 1 (var int script) + 22 (p2wkh output)
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p2wkhOutputSize = 8 + 1 + 22
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// p2wkhOutputSize is an estimate of the p2wsh funding uotput.
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p2wshOutputSize = 8 + 1 + 34
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)
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var estimatedSize int
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amtNeeded := amt
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for {
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// First perform an initial round of coin selection to estimate
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@ -1455,10 +1430,20 @@ func coinSelect(feeRate uint64, amt btcutil.Amount,
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return nil, 0, err
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}
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// Based on the selected coins, estimate the size of the final
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// fully signed transaction.
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estimatedSize = ((len(selectedUtxos) * p2wkhSpendSize) +
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p2wshOutputSize + txOverhead)
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var weightEstimate TxWeightEstimator
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for range selectedUtxos {
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// Assume all selected inputs are P2WKH inputs.
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// TODO: Handle wallets that have non-witness UTXOs.
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weightEstimate.AddP2WKHInput()
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}
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// Channel funding multisig output is P2WSH.
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weightEstimate.AddP2WSHOutput()
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// Assume that change output is a P2WKH output.
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// TODO: Handle wallets that generate non-witness change addresses.
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weightEstimate.AddP2WKHOutput()
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// The difference between the selected amount and the amount
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// requested will be used to pay fees, and generate a change
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@ -1469,9 +1454,10 @@ func coinSelect(feeRate uint64, amt btcutil.Amount,
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// amount isn't enough to pay fees, then increase the requested
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// coin amount by the estimate required fee, performing another
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// round of coin selection.
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requiredFee := btcutil.Amount(uint64(estimatedSize) * feeRate)
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requiredFee := btcutil.Amount(
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uint64(weightEstimate.Weight()) * feeRatePerWeight)
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if overShootAmt < requiredFee {
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amtNeeded += requiredFee
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amtNeeded = amt + requiredFee
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continue
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}
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