From 08f51c7d5ff1d9367c127b287ec5d6acc36d210f Mon Sep 17 00:00:00 2001
From: Jonathan Downing <jonathan@dominantstrategies.io>
Date: Wed, 25 Sep 2024 13:07:52 -0500
Subject: [PATCH] Prevent worker from unintentionally double-spending UTXOs

---
 core/worker.go | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/core/worker.go b/core/worker.go
index 91a9fd2d2..5627bcb86 100644
--- a/core/worker.go
+++ b/core/worker.go
@@ -1531,7 +1531,7 @@ func (w *worker) processQiTx(tx *types.Transaction, env *environment, parent *ty
 
 	addresses := make(map[common.AddressBytes]struct{})
 	totalQitIn := big.NewInt(0)
-	utxosDelete := make(map[types.OutPoint]*types.UtxoEntry)
+	utxosDeleteHashes := make([]common.Hash, 0, len(tx.TxIn()))
 	inputs := make(map[uint]uint64)
 	for _, txIn := range tx.TxIn() {
 		utxo := rawdb.GetUTXO(w.workerDb, txIn.PreviousOutPoint.TxHash, txIn.PreviousOutPoint.Index)
@@ -1557,7 +1557,12 @@ func (w *worker) processQiTx(tx *types.Transaction, env *environment, parent *ty
 		}
 		addresses[common.AddressBytes(utxo.Address)] = struct{}{}
 		totalQitIn.Add(totalQitIn, types.Denominations[denomination])
-		utxosDelete[txIn.PreviousOutPoint] = utxo
+		utxoHash := types.UTXOHash(txIn.PreviousOutPoint.TxHash, txIn.PreviousOutPoint.Index, utxo)
+		if _, exists := env.deletedUtxos[utxoHash]; exists {
+			return fmt.Errorf("tx %032x double spends UTXO %032x:%d", tx.Hash(), txIn.PreviousOutPoint.TxHash, txIn.PreviousOutPoint.Index)
+		}
+		env.deletedUtxos[utxoHash] = struct{}{}
+		utxosDeleteHashes = append(utxosDeleteHashes, utxoHash)
 		inputs[uint(denomination)]++
 	}
 	var ETXRCount int
@@ -1565,7 +1570,7 @@ func (w *worker) processQiTx(tx *types.Transaction, env *environment, parent *ty
 	etxs := make([]*types.ExternalTx, 0)
 	totalQitOut := big.NewInt(0)
 	totalConvertQitOut := big.NewInt(0)
-	utxosCreate := make(map[types.OutPoint]*types.UtxoEntry)
+	utxosCreateHashes := make([]common.Hash, 0, len(tx.TxOut()))
 	conversion := false
 	var convertAddress common.Address
 	outputs := make(map[uint]uint64)
@@ -1650,7 +1655,7 @@ func (w *worker) processQiTx(tx *types.Transaction, env *environment, parent *ty
 		} else {
 			// This output creates a normal UTXO
 			utxo := types.NewUtxoEntry(&txOut)
-			utxosCreate[types.OutPoint{TxHash: tx.Hash(), Index: uint16(txOutIdx)}] = utxo
+			utxosCreateHashes = append(utxosCreateHashes, types.UTXOHash(tx.Hash(), uint16(txOutIdx), utxo))
 		}
 	}
 	// Ensure the transaction does not spend more than its inputs.
@@ -1708,18 +1713,10 @@ func (w *worker) processQiTx(tx *types.Transaction, env *environment, parent *ty
 	}
 	env.txs = append(env.txs, tx)
 	env.utxoFees.Add(env.utxoFees, txFeeInQit)
-	for outpoint, utxo := range utxosDelete {
-		utxoHash := types.UTXOHash(outpoint.TxHash, outpoint.Index, utxo)
-		if _, exists := env.deletedUtxos[utxoHash]; exists {
-			return fmt.Errorf("tx %032x double spends UTXO %032x:%d", tx.Hash(), outpoint.TxHash, outpoint.Index)
-		}
-		env.deletedUtxos[utxoHash] = struct{}{}
-		env.utxosDelete = append(env.utxosDelete, utxoHash)
-	}
-	for outPoint, utxo := range utxosCreate {
-		utxoHash := types.UTXOHash(outPoint.TxHash, outPoint.Index, utxo)
-		env.utxosCreate = append(env.utxosCreate, utxoHash)
-	}
+
+	env.utxosDelete = append(env.utxosDelete, utxosDeleteHashes...)
+	env.utxosCreate = append(env.utxosCreate, utxosCreateHashes...)
+
 	if err := CheckDenominations(inputs, outputs); err != nil {
 		return err
 	}