fix: use EffectiveGasPrice in ante handler for dynamic fee tx (#817)

* Use effectiveGasPrice in ante handler for dynamic fee tx

Closes: #814

Solution:
- use effectiveGasPrice when check minimal-gas-prices, and deduct fee in ante handler
- implement an EthMempoolFeeDecorator

* add effectiveGasPrice to tx receipt

* changelog

* fix unit test

* fix comments

* add comments

* Apply suggestions from code review

Co-authored-by: Thomas Nguy <81727899+thomas-nguy@users.noreply.github.com>

* review suggestions

Co-authored-by: Thomas Nguy <81727899+thomas-nguy@users.noreply.github.com>
Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>

x/evm/types/access_list_tx.go

@@ -229,3 +229,13 @@ func (tx AccessListTx) Fee() *big.Int {
 func (tx AccessListTx) Cost() *big.Int {
 	return cost(tx.Fee(), tx.GetValue())
 }
+
+// EffectiveFee is the same as Fee for AccessListTx
+func (tx AccessListTx) EffectiveFee(baseFee *big.Int) *big.Int {
+	return tx.Fee()
+}
+
+// EffectiveCost is the same as Cost for AccessListTx
+func (tx AccessListTx) EffectiveCost(baseFee *big.Int) *big.Int {
+	return tx.Cost()
+}

x/evm/types/dynamic_fee_tx.go

@@ -7,6 +7,7 @@ import (
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/common/math"
 	ethtypes "github.com/ethereum/go-ethereum/core/types"
 
 	"github.com/tharsis/ethermint/types"
@@ -256,10 +257,25 @@ func (tx DynamicFeeTx) Validate() error {
 
 // Fee returns gasprice * gaslimit.
 func (tx DynamicFeeTx) Fee() *big.Int {
-	return fee(tx.GetGasPrice(), tx.GasLimit)
+	return fee(tx.GetGasFeeCap(), tx.GasLimit)
 }
 
 // Cost returns amount + gasprice * gaslimit.
 func (tx DynamicFeeTx) Cost() *big.Int {
 	return cost(tx.Fee(), tx.GetValue())
 }
+
+// GetEffectiveGasPrice returns the effective gas price
+func (tx *DynamicFeeTx) GetEffectiveGasPrice(baseFee *big.Int) *big.Int {
+	return math.BigMin(new(big.Int).Add(tx.GasTipCap.BigInt(), baseFee), tx.GasFeeCap.BigInt())
+}
+
+// EffectiveFee returns effective_gasprice * gaslimit.
+func (tx DynamicFeeTx) EffectiveFee(baseFee *big.Int) *big.Int {
+	return fee(tx.GetEffectiveGasPrice(baseFee), tx.GasLimit)
+}
+
+// EffectiveCost returns amount + effective_gasprice * gaslimit.
+func (tx DynamicFeeTx) EffectiveCost(baseFee *big.Int) *big.Int {
+	return cost(tx.EffectiveFee(baseFee), tx.GetValue())
+}

x/evm/types/legacy_tx.go

@@ -200,3 +200,13 @@ func (tx LegacyTx) Fee() *big.Int {
 func (tx LegacyTx) Cost() *big.Int {
 	return cost(tx.Fee(), tx.GetValue())
 }
+
+// EffectiveFee is the same as Fee for LegacyTx
+func (tx LegacyTx) EffectiveFee(baseFee *big.Int) *big.Int {
+	return tx.Fee()
+}
+
+// EffectiveCost is the same as Cost for LegacyTx
+func (tx LegacyTx) EffectiveCost(baseFee *big.Int) *big.Int {
+	return tx.Cost()
+}

x/evm/types/msg.go

@@ -245,6 +245,24 @@ func (msg MsgEthereumTx) GetGas() uint64 {
 	return txData.GetGas()
 }
 
+// GetFee returns the fee for non dynamic fee tx
+func (msg MsgEthereumTx) GetFee() *big.Int {
+	txData, err := UnpackTxData(msg.Data)
+	if err != nil {
+		return nil
+	}
+	return txData.Fee()
+}
+
+// GetEffectiveFee returns the fee for dynamic fee tx
+func (msg MsgEthereumTx) GetEffectiveFee(baseFee *big.Int) *big.Int {
+	txData, err := UnpackTxData(msg.Data)
+	if err != nil {
+		return nil
+	}
+	return txData.EffectiveFee(baseFee)
+}
+
 // GetFrom loads the ethereum sender address from the sigcache and returns an
 // sdk.AccAddress from its bytes
 func (msg *MsgEthereumTx) GetFrom() sdk.AccAddress {

x/evm/types/tx_data.go

@@ -36,8 +36,14 @@ type TxData interface {
 
 	AsEthereumData() ethtypes.TxData
 	Validate() error
+
+	// static fee
 	Fee() *big.Int
 	Cost() *big.Int
+
+	// effective fee according to current base fee
+	EffectiveFee(baseFee *big.Int) *big.Int
+	EffectiveCost(baseFee *big.Int) *big.Int
 }
 
 func NewTxDataFromTx(tx *ethtypes.Transaction) (TxData, error) {