Fix allow underpriced tx processing

Signed-off-by: Fabio Di Fabio <fabio.difabio@consensys.net>

Author: fab-10

ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/AbstractEstimateGas.java

@@ -204,7 +204,7 @@ protected static TransactionValidationParams getTransactionValidationParams(
 
     return isAllowExceedingBalance
         ? TransactionValidationParams.transactionSimulatorAllowExceedingBalanceAndFutureNonce()
-        : TransactionValidationParams.transactionSimulatorEstimateGasParams();
+        : TransactionValidationParams.transactionSimulatorAllowUnderpricedAndFutureNonce();
   }
 
   @VisibleForTesting

ethereum/api/src/test/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/methods/EthEstimateGasTest.java

@@ -444,7 +444,7 @@ public void shouldNotIgnoreSenderBalanceByDefault() {
                 modifiedLegacyTransactionCallParameter(
                     Long.MAX_VALUE, Wei.ZERO, OptionalLong.empty(), Optional.empty())),
             eq(Optional.empty()), // no account overrides
-            eq(TransactionValidationParams.transactionSimulatorEstimateGasParams()),
+            eq(TransactionValidationParams.transactionSimulatorAllowUnderpricedAndFutureNonce()),
             any(OperationTracer.class),
             eq(pendingBlockHeader));
   }

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/MainnetTransactionProcessor.java

@@ -494,17 +494,23 @@ public TransactionProcessingResult processTransaction(
       final CoinbaseFeePriceCalculator coinbaseCalculator;
       if (blockHeader.getBaseFee().isPresent()) {
         final Wei baseFee = blockHeader.getBaseFee().get();
-        if (transactionGasPrice.compareTo(baseFee) < 0) {
-          return TransactionProcessingResult.failed(
-              gasUsedByTransaction,
-              refundedGas,
-              ValidationResult.invalid(
-                  TransactionInvalidReason.TRANSACTION_PRICE_TOO_LOW,
-                  "transaction price must be greater than base fee"),
-              Optional.empty(),
-              Optional.empty());
+        final boolean gasPriceBelowBaseFee = transactionGasPrice.compareTo(baseFee) < 0;
+        if (transactionValidationParams.allowUnderpriced()) {
+          coinbaseCalculator =
+              gasPriceBelowBaseFee ? (a, b, c) -> Wei.ZERO : coinbaseFeePriceCalculator;
+        } else {
+          if (gasPriceBelowBaseFee) {
+            return TransactionProcessingResult.failed(
+                gasUsedByTransaction,
+                refundedGas,
+                ValidationResult.invalid(
+                    TransactionInvalidReason.TRANSACTION_PRICE_TOO_LOW,
+                    "transaction price must be greater than base fee"),
+                Optional.empty(),
+                Optional.empty());
+          }
+          coinbaseCalculator = coinbaseFeePriceCalculator;
         }
-        coinbaseCalculator = coinbaseFeePriceCalculator;
       } else {
         coinbaseCalculator = CoinbaseFeePriceCalculator.frontier();
       }

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/mainnet/TransactionValidationParams.java

@@ -38,7 +38,7 @@ public interface TransactionValidationParams {
   TransactionValidationParams transactionSimulatorParamsAllowFutureNonce =
       ImmutableTransactionValidationParams.of(true, false, false, false, false, true);
 
-  TransactionValidationParams transactionSimulatorEstimateGasParams =
+  TransactionValidationParams transactionSimulatorAllowUnderpricedAndFutureNonceParams =
       ImmutableTransactionValidationParams.of(true, false, true, false, false, true);
 
   TransactionValidationParams transactionSimulatorAllowExceedingBalanceParams =
@@ -85,8 +85,8 @@ static TransactionValidationParams transactionSimulatorAllowFutureNonce() {
     return transactionSimulatorParamsAllowFutureNonce;
   }
 
-  static TransactionValidationParams transactionSimulatorEstimateGasParams() {
-    return transactionSimulatorEstimateGasParams;
+  static TransactionValidationParams transactionSimulatorAllowUnderpricedAndFutureNonce() {
+    return transactionSimulatorAllowUnderpricedAndFutureNonceParams;
   }
 
   static TransactionValidationParams transactionSimulatorAllowExceedingBalance() {

ethereum/core/src/main/java/org/hyperledger/besu/ethereum/transaction/TransactionSimulator.java

@@ -414,8 +414,7 @@ public Optional<TransactionSimulatorResult> processWithWorldUpdater(
     final Address senderAddress = callParams.getSender().orElse(DEFAULT_FROM);
 
     final ProcessableBlockHeader blockHeaderToProcess;
-    if ((transactionValidationParams.isAllowExceedingBalance()
-            || transactionValidationParams.allowUnderpriced())
+    if (transactionValidationParams.isAllowExceedingBalance()
         && processableHeader.getBaseFee().isPresent()) {
       blockHeaderToProcess =
           new BlockHeaderBuilder()