. presignedOnly argument of SignTx

This is needed to implement ensurePresigned as read-only, so it only checks if
a presigned transaction exists, not tries to sign it.

Author: starius

sweepbatcher/presigned.go

@@ -51,10 +51,11 @@ func (b *batch) ensurePresigned(ctx context.Context, newSweep *sweep) error {
 			"for feeRate %v: %w", feeRate, err)
 	}
 
-	// Try to presign this transaction.
+	// Check of a presigned transaction exists.
 	batchAmt := newSweep.value
+	const presignedOnly = true
 	signedTx, err := b.cfg.presignedHelper.SignTx(
-		ctx, tx, batchAmt, feeRate, feeRate,
+		ctx, tx, batchAmt, feeRate, feeRate, presignedOnly,
 	)
 	if err != nil {
 		return fmt.Errorf("failed to sign unsigned tx %v "+
@@ -271,8 +272,9 @@ func (b *batch) publishPresigned(ctx context.Context) (btcutil.Amount, error,
 
 	// Get a signed transaction. It may be either new transaction or a
 	// pre-signed one.
+	const presignedOnly = false
 	signedTx, err := b.cfg.presignedHelper.SignTx(
-		ctx, tx, batchAmt, minRelayFee, feeRate,
+		ctx, tx, batchAmt, minRelayFee, feeRate, presignedOnly,
 	)
 	if err != nil {
 		return 0, fmt.Errorf("failed to sign tx: %w", err),

sweepbatcher/sweep_batcher.go

@@ -189,10 +189,11 @@ type PresignedHelper interface {
 	//   - transaction version must be the same;
 	//   - Sequence numbers in the inputs must be preserved.
 	// When choosing a presigned transaction, a transaction with fee rate
-	// closer to the fee rate passed is selected.
+	// closer to the fee rate passed is selected. If presignedOnly is set,
+	// it doesn't try to sign the transaction and only loads a presigned tx.
 	SignTx(ctx context.Context, tx *wire.MsgTx, inputAmt btcutil.Amount,
-		minRelayFee, feeRate chainfee.SatPerKWeight) (*wire.MsgTx,
-		error)
+		minRelayFee, feeRate chainfee.SatPerKWeight,
+		presignedOnly bool) (*wire.MsgTx, error)
 
 	// CleanupTransactions removes all transactions related to any of the
 	// outpoints. Should be called after sweep batch tx is fully confirmed.

sweepbatcher/sweep_batcher_test.go

@@ -4152,14 +4152,15 @@ func (h *mockPresignedHelper) DestPkScript(ctx context.Context,
 // the exact transaction passed and adds it to presignedBatches. Otherwise it
 // looks for a transaction in presignedBatches satisfying the criteria.
 func (h *mockPresignedHelper) SignTx(ctx context.Context, tx *wire.MsgTx,
-	inputAmt btcutil.Amount,
-	minRelayFee, feeRate chainfee.SatPerKWeight) (*wire.MsgTx, error) {
+	inputAmt btcutil.Amount, minRelayFee, feeRate chainfee.SatPerKWeight,
+	presignedOnly bool) (*wire.MsgTx, error) {
 
 	h.mu.Lock()
 	defer h.mu.Unlock()
 
-	// If all the inputs are online, sign this exact transaction.
-	if offline := h.offlineInputs(tx); len(offline) == 0 {
+	// If all the inputs are online and presignedOnly is not set, sign
+	// this exact transaction.
+	if offline := h.offlineInputs(tx); len(offline) == 0 && !presignedOnly {
 		tx = tx.Copy()
 		h.sign(tx)
 
@@ -4298,9 +4299,9 @@ func testPresigned_input1_offline_then_input2(t *testing.T,
 		WithCustomFeeRate(customFeeRate),
 		WithPresignedHelper(presignedHelper))
 
+	batcherErrChan := make(chan error)
 	go func() {
-		err := batcher.Run(ctx)
-		checkBatcherError(t, err)
+		batcherErrChan <- batcher.Run(ctx)
 	}()
 
 	setFeeRate(feeRateLow)
@@ -4318,6 +4319,25 @@ func testPresigned_input1_offline_then_input2(t *testing.T,
 		Notifier: &dummyNotifier,
 	}
 
+	// Make sure that the batcher crashes if AddSweep is called before
+	// PresignSweep even if the input is online.
+	presignedHelper.SetOutpointOnline(op1, true)
+	require.NoError(t, batcher.AddSweep(&sweepReq1))
+	err = <-batcherErrChan
+	require.Error(t, err)
+	require.ErrorContains(t, err, "PresignSweep was not called")
+
+	// Start the batcher again.
+	batcher = NewBatcher(lnd.WalletKit, lnd.ChainNotifier, lnd.Signer,
+		testMuSig2SignSweep, testVerifySchnorrSig, lnd.ChainParams,
+		batcherStore, &dummySweepFetcherMock{},
+		WithCustomFeeRate(customFeeRate),
+		WithPresignedHelper(presignedHelper))
+	go func() {
+		err := batcher.Run(ctx)
+		checkBatcherError(t, err)
+	}()
+
 	// This should fail, because the input is offline.
 	presignedHelper.SetOutpointOnline(op1, false)
 	err = batcher.PresignSweep(ctx, op1, 1_000_000, sweepTimeout, destAddr)
@@ -4429,9 +4449,10 @@ func testPresigned_input1_offline_then_input2(t *testing.T,
 
 	// Make sure we still have presigned transactions for the second batch.
 	presignedHelper.SetOutpointOnline(op2, false)
+	const presignedOnly = true
 	_, err = presignedHelper.SignTx(
 		ctx, batch2, 2_000_000, chainfee.FeePerKwFloor,
-		chainfee.FeePerKwFloor,
+		chainfee.FeePerKwFloor, presignedOnly,
 	)
 	require.NoError(t, err)
 }