fee: round up weight to the nearest satoshi

hieblmi · hieblmi · commit 547d263d598a · 2025-07-17T20:59:36.000+02:00
this commit fixes cases where a rounded down
transaction weight leads to undershooting of
the minimum relay fee.
diff --git a/instantout/instantout.go b/instantout/instantout.go
@@ -169,7 +169,7 @@ func (i *InstantOut) createHtlcTransaction(network *chaincfg.Params) (
 
 	// Estimate the fee
 	weight := htlcWeight(len(inputReservations))
-	fee := i.htlcFeeRate.FeeForWeight(weight)
+	fee := i.htlcFeeRate.FeeForWeightRoundUp(weight)
 	if fee > i.Value/5 {
 		return nil, errors.New("fee is higher than 20% of " +
 			"sweep value")
@@ -213,7 +213,7 @@ func (i *InstantOut) createSweeplessSweepTx(feerate chainfee.SatPerKWeight) (
 
 	// Estimate the fee
 	weight := sweeplessSweepWeight(len(inputReservations))
-	fee := feerate.FeeForWeight(weight)
+	fee := feerate.FeeForWeightRoundUp(weight)
 	if fee > i.Value/5 {
 		return nil, errors.New("fee is higher than 20% of " +
 			"sweep value")
@@ -381,7 +381,7 @@ func (i *InstantOut) generateHtlcSweepTx(ctx context.Context,
 		return nil, err
 	}
 
-	fee := feeRate.FeeForWeight(weightEstimator.Weight())
+	fee := feeRate.FeeForWeightRoundUp(weightEstimator.Weight())
 
 	htlcOutValue := i.finalizedHtlcTx.TxOut[0].Value
 	output := &wire.TxOut{
diff --git a/instantout/manager.go b/instantout/manager.go
@@ -248,7 +248,7 @@ func (m *Manager) GetInstantOutQuote(ctx context.Context,
 
 	// The on chain chainFee is the chainFee rate times the estimated
 	// sweepless sweep transaction size.
-	chainFee := feeRate.FeeForWeight(sweeplessSweepWeight(len(reservationIDs)))
+	chainFee := feeRate.FeeForWeightRoundUp(sweeplessSweepWeight(len(reservationIDs)))
 
 	return Quote{
 		ServiceFee: btcutil.Amount(quoteRes.SwapFee),
diff --git a/liquidity/loopin.go b/liquidity/loopin.go
@@ -78,5 +78,5 @@ func loopInSweepFee(fee chainfee.SatPerKWeight) btcutil.Amount {
 
 	estimator.AddWitnessInput(maxSize)
 
-	return fee.FeeForWeight(estimator.Weight())
+	return fee.FeeForWeightRoundUp(estimator.Weight())
 }
diff --git a/loopout_feerate_test.go b/loopout_feerate_test.go
@@ -76,7 +76,7 @@ func (s testSweeper) GetSweepFeeDetails(ctx context.Context,
 	// Find weight.
 	weight := weightEstimate.Weight()
 
-	return feeRate.FeeForWeight(weight), feeRate, weight, nil
+	return feeRate.FeeForWeightRoundUp(weight), feeRate, weight, nil
 }
 
 // TestLoopOutSweepFeerateProvider tests that loopOutSweepFeerateProvider
diff --git a/loopout_test.go b/loopout_test.go
@@ -436,7 +436,7 @@ func testCustomSweepConfTarget(t *testing.T) {
 		)
 		require.NoError(t, err, "unable to retrieve fee estimate")
 
-		minFee := feeRate.FeeForWeight(lntypes.WeightUnit(weight))
+		minFee := feeRate.FeeForWeightRoundUp(lntypes.WeightUnit(weight))
 		// Just an estimate that works to sanity check fee upper bound.
 		maxFee := btcutil.Amount(float64(minFee) * 1.5)
 
diff --git a/staticaddr/deposit/actions.go b/staticaddr/deposit/actions.go
@@ -48,7 +48,7 @@ func (f *FSM) PublishDepositExpirySweepAction(ctx context.Context,
 
 	weight := script.ExpirySpendWeight()
 
-	fee := feeRateEstimator.FeeForWeight(lntypes.WeightUnit(weight))
+	fee := feeRateEstimator.FeeForWeightRoundUp(lntypes.WeightUnit(weight))
 
 	// We cap the fee at 20% of the deposit value.
 	if fee > f.deposit.Value/5 {
diff --git a/staticaddr/loopin/actions.go b/staticaddr/loopin/actions.go
@@ -212,7 +212,7 @@ func (f *FSM) InitHtlcAction(ctx context.Context,
 		f.cfg.MaxStaticAddrHtlcBackupFeePercentage)
 
 	feeRate := chainfee.SatPerKWeight(loopInResp.StandardHtlcInfo.FeeRate)
-	fee := feeRate.FeeForWeight(f.loopIn.htlcWeight())
+	fee := feeRate.FeeForWeightRoundUp(f.loopIn.htlcWeight())
 	if fee > maxHtlcTxFee {
 		// Abort the swap by pushing empty sigs to the server.
 		pushEmptySigs()
@@ -225,7 +225,7 @@ func (f *FSM) InitHtlcAction(ctx context.Context,
 	f.loopIn.HtlcTxFeeRate = feeRate
 
 	highFeeRate := chainfee.SatPerKWeight(loopInResp.HighFeeHtlcInfo.FeeRate)
-	fee = highFeeRate.FeeForWeight(f.loopIn.htlcWeight())
+	fee = highFeeRate.FeeForWeightRoundUp(f.loopIn.htlcWeight())
 	if fee > maxHtlcTxBackupFee {
 		// Abort the swap by pushing empty sigs to the server.
 		pushEmptySigs()
@@ -241,7 +241,7 @@ func (f *FSM) InitHtlcAction(ctx context.Context,
 	extremelyHighFeeRate := chainfee.SatPerKWeight(
 		loopInResp.ExtremeFeeHtlcInfo.FeeRate,
 	)
-	fee = extremelyHighFeeRate.FeeForWeight(f.loopIn.htlcWeight())
+	fee = extremelyHighFeeRate.FeeForWeightRoundUp(f.loopIn.htlcWeight())
 	if fee > maxHtlcTxBackupFee {
 		// Abort the swap by pushing empty sigs to the server.
 		pushEmptySigs()
diff --git a/staticaddr/loopin/loopin.go b/staticaddr/loopin/loopin.go
@@ -285,7 +285,7 @@ func (l *StaticAddressLoopIn) createHtlcTx(chainParams *chaincfg.Params,
 
 	// Calculate htlc tx fee for server provided fee rate.
 	weight := l.htlcWeight()
-	fee := feeRate.FeeForWeight(weight)
+	fee := feeRate.FeeForWeightRoundUp(weight)
 
 	// Check if the server breaches our fee limits.
 	amt := float64(l.TotalDepositAmount())
@@ -389,7 +389,7 @@ func (l *StaticAddressLoopIn) createHtlcSweepTx(ctx context.Context,
 		return nil, err
 	}
 
-	fee := feeRate.FeeForWeight(weightEstimator.Weight())
+	fee := feeRate.FeeForWeightRoundUp(weightEstimator.Weight())
 
 	htlcOutValue := htlcTx.TxOut[0].Value
 	output := &wire.TxOut{
diff --git a/staticaddr/withdraw/manager.go b/staticaddr/withdraw/manager.go
@@ -826,7 +826,7 @@ func (m *Manager) createWithdrawalTx(ctx context.Context,
 	if err != nil {
 		return nil, 0, 0, err
 	}
-	feeWithoutChange := feeRate.FeeForWeight(weight)
+	feeWithoutChange := feeRate.FeeForWeightRoundUp(weight)
 
 	// If the user selected a fraction of the sum of the selected deposits
 	// to withdraw, check if a change output is needed.
@@ -839,7 +839,7 @@ func (m *Manager) createWithdrawalTx(ctx context.Context,
 		if err != nil {
 			return nil, 0, 0, err
 		}
-		feeWithChange := feeRate.FeeForWeight(weight)
+		feeWithChange := feeRate.FeeForWeightRoundUp(weight)
 
 		// The available change that can cover fees is the total
 		// selected deposit amount minus the selected withdrawal amount.
diff --git a/sweep/sweeper.go b/sweep/sweeper.go
@@ -226,7 +226,7 @@ func (s *Sweeper) GetSweepFeeDetails(ctx context.Context,
 	weight := weightEstimate.Weight()
 
 	// Find fee.
-	fee := feeRate.FeeForWeight(weight)
+	fee := feeRate.FeeForWeightRoundUp(weight)
 
 	log.Debugf("Estimations for a tx (label=%s): weight=%v, fee=%v, "+
 		"feerate=%v, sweepConfTarget=%d.", label, weight, fee, feeRate,
diff --git a/sweepbatcher/greedy_batch_selection.go b/sweepbatcher/greedy_batch_selection.go
@@ -249,7 +249,7 @@ type feeDetails struct {
 
 // fee returns fee of onchain transaction representing this instance.
 func (e feeDetails) fee() btcutil.Amount {
-	return e.FeeRate.FeeForWeight(e.Weight)
+	return e.FeeRate.FeeForWeightRoundUp(e.Weight)
 }
 
 // combine returns new feeDetails, combining properties.
diff --git a/sweepbatcher/sweep_batch.go b/sweepbatcher/sweep_batch.go
@@ -1305,7 +1305,7 @@ func constructUnsignedTx(sweeps []sweep, address btcutil.Address,
 
 	// Find weight and fee.
 	weight := weightEstimate.Weight()
-	feeForWeight := feeRate.FeeForWeight(weight)
+	feeForWeight := feeRate.FeeForWeightRoundUp(weight)
 
 	// Fee can be rounded towards zero, leading to actual feeRate being
 	// slightly lower than the requested value. Increase the fee if this is
diff --git a/sweepbatcher/sweep_batcher_test.go b/sweepbatcher/sweep_batcher_test.go
@@ -3787,7 +3787,7 @@ func testSweepFetcher(t *testing.T, store testStore,
 	feeRate := chainfee.SatPerKWeight(30000)
 	amt := btcutil.Amount(1_000_000)
 	weight := lntypes.WeightUnit(396) // Weight for 1-to-1 tx.
-	expectedFee := feeRate.FeeForWeight(weight)
+	expectedFee := feeRate.FeeForWeightRoundUp(weight)
 
 	swap := &loopdb.LoopOutContract{
 		SwapContract: loopdb.SwapContract{
@@ -4285,7 +4285,7 @@ func testWithMixedBatch(t *testing.T, store testStore,
 		}
 		amt := btcutil.Amount(1_000_000 * (i + 1))
 		weight := wantWeights[i]
-		expectedFee := feeRate.FeeForWeight(weight)
+		expectedFee := feeRate.FeeForWeightRoundUp(weight)
 
 		// Check weight.
 		gotWeight := lntypes.WeightUnit(
@@ -4453,7 +4453,7 @@ func testWithMixedBatchCustom(t *testing.T, store testStore,
 	// Calculate expected values.
 	feeRate := test.DefaultMockFee
 	amt := btcutil.Amount(1_000_000 * len(preimages))
-	expectedFee := feeRate.FeeForWeight(wantWeight)
+	expectedFee := feeRate.FeeForWeightRoundUp(wantWeight)
 
 	// Check weight.
 	gotWeight := lntypes.WeightUnit(

Original file line number	Diff line number	Diff line change
`@@ -78,5 +78,5 @@ func loopInSweepFee(fee chainfee.SatPerKWeight) btcutil.Amount {`
`78`	`78`
`79`	`79`	`estimator.AddWitnessInput(maxSize)`
`80`	`80`
`81`		`- return fee.FeeForWeight(estimator.Weight())`
	`81`	`+ return fee.FeeForWeightRoundUp(estimator.Weight())`
`82`	`82`	`}`
Original file line number	Diff line number	Diff line change
`@@ -76,7 +76,7 @@ func (s testSweeper) GetSweepFeeDetails(ctx context.Context,`
`76`	`76`	`// Find weight.`
`77`	`77`	`weight := weightEstimate.Weight()`
`78`	`78`
`79`		`- return feeRate.FeeForWeight(weight), feeRate, weight, nil`
	`79`	`+ return feeRate.FeeForWeightRoundUp(weight), feeRate, weight, nil`
`80`	`80`	`}`
`81`	`81`
`82`	`82`	`// TestLoopOutSweepFeerateProvider tests that loopOutSweepFeerateProvider`
Original file line number	Diff line number	Diff line change
`@@ -436,7 +436,7 @@ func testCustomSweepConfTarget(t *testing.T) {`
`436`	`436`	`)`
`437`	`437`	`require.NoError(t, err, "unable to retrieve fee estimate")`
`438`	`438`
`439`		`- minFee := feeRate.FeeForWeight(lntypes.WeightUnit(weight))`
	`439`	`+ minFee := feeRate.FeeForWeightRoundUp(lntypes.WeightUnit(weight))`
`440`	`440`	`// Just an estimate that works to sanity check fee upper bound.`
`441`	`441`	`maxFee := btcutil.Amount(float64(minFee) * 1.5)`
`442`	`442`