fix: make gas refunds error free and panic safe

app/app.go

@@ -367,7 +367,7 @@ func (app *MinitiaApp) SetCheckTx(handler blockchecktx.CheckTx) {
 
 func (app *MinitiaApp) setPostHandler() {
 	app.SetPostHandler(posthandler.NewPostHandler(
-		app.AccountKeeper,
+		app.Logger(),
 		app.EVMKeeper,
 	))
 }

app/posthandler/gasrefund.go

@@ -4,6 +4,7 @@
 	"fmt"
 
 	errorsmod "cosmossdk.io/errors"
+	"cosmossdk.io/log"
 	"cosmossdk.io/math"
 	storetypes "cosmossdk.io/store/types"
 
@@ -17,12 +18,14 @@
 var _ sdk.PostDecorator = &GasRefundDecorator{}
 
 type GasRefundDecorator struct {
-	ek EVMKeeper
+	logger log.Logger
+	ek     EVMKeeper
 }
 
-func NewGasRefundDecorator(ek EVMKeeper) sdk.PostDecorator {
+func NewGasRefundDecorator(logger log.Logger, ek EVMKeeper) sdk.PostDecorator {
+	logger = logger.With("module", "gas_refund")
 	return &GasRefundDecorator{
-		ek,
+		logger, ek,
 	}
 }
 
@@ -70,20 +73,40 @@
 			sdk.NewAttribute(AttributeKeyCoins, coinsRefund.String()),
 		))
 
-		// TODO - should we charge gas for refund?
-		//
-		// for now, we use infinite gas meter to prevent out of gas error or inconsistency between
-		// used gas and refunded gas.
-		feeCollectorAddr := authtypes.NewModuleAddress(authtypes.FeeCollectorName)
-		err = erd.ek.ERC20Keeper().SendCoins(ctx.WithGasMeter(storetypes.NewInfiniteGasMeter()), feeCollectorAddr, feePayer, coinsRefund)
-		if err != nil {
-			return ctx, err
-		}
+		// conduct gas refund
+		erd.safeRefund(ctx, feePayer, coinsRefund)
 	}
 
 	return next(ctx, tx, simulate, success)
 }
 
+func (erd *GasRefundDecorator) safeRefund(ctx sdk.Context, feePayer sdk.AccAddress, coinsRefund sdk.Coins) {
+	defer func() {
+		if r := recover(); r != nil {
+			switch r := r.(type) {
+			case storetypes.ErrorOutOfGas:
+				erd.logger.Error("failed to refund gas", "err", r)
+			default:
+				panic(r)
+			}
+		}
+	}()
+
+	// prepare context for refund operation
+	const gasLimitForRefund = 1_000_000
+	cacheCtx, commit := ctx.CacheContext()
+	cacheCtx = cacheCtx.WithGasMeter(storetypes.NewGasMeter(gasLimitForRefund))
+
+	feeCollectorAddr := authtypes.NewModuleAddress(authtypes.FeeCollectorName)
+	err := erd.ek.ERC20Keeper().SendCoins(cacheCtx, feeCollectorAddr, feePayer, coinsRefund)
+	if err != nil {
+		erd.logger.Error("failed to refund gas", "err", err)
+		return
+	}
+
+	commit()
+}
+
 const (
 	EventTypeGasRefund = "gas_refund"
 	AttributeKeyGas    = "gas"

app/posthandler/posthandler.go

@@ -3,20 +3,20 @@ package posthandler
 import (
 	"context"
 
+	"cosmossdk.io/log"
 	"cosmossdk.io/math"
 	sdk "github.com/cosmos/cosmos-sdk/types"
-	authante "github.com/cosmos/cosmos-sdk/x/auth/ante"
 
 	evmtypes "github.com/initia-labs/minievm/x/evm/types"
 )
 
 // NewPostHandler returns a new sdk.PostHandler that is composed of the sdk.ChainPostDecorators
 func NewPostHandler(
-	ak authante.AccountKeeper,
+	logger log.Logger,
 	ek EVMKeeper,
 ) sdk.PostHandler {
 	return sdk.ChainPostDecorators(
-		NewGasRefundDecorator(ek),
+		NewGasRefundDecorator(logger, ek),
 	)
 }
 

x/evm/keeper/txutils.go

@@ -225,7 +225,7 @@ func (u *TxUtils) ConvertCosmosTxToEthereumTx(ctx context.Context, sdkTx sdk.Tx)
 		return nil, nil, err
 	}
 
-	if len(fees) > 0 && fees[0].Denom != params.FeeDenom {
+	if !(len(fees) == 0 || (len(fees) == 1 && fees[0].Denom == params.FeeDenom)) {
 		return nil, nil, nil
 	}
 
@@ -403,7 +403,7 @@ func (u *TxUtils) IsEthereumTx(ctx context.Context, sdkTx sdk.Tx) (bool, error)
 		return false, err
 	}
 
-	if len(fees) > 0 && fees[0].Denom != params.FeeDenom {
+	if !(len(fees) == 0 || (len(fees) == 1 && fees[0].Denom == params.FeeDenom)) {
 		return false, nil
 	}