ante: switch ethAnteHandler to use AnteDecorators (#252)

* ante: switch ethAnteHandler to use AnteDecorators

* ante: cleanup panic recover, update MsgEthereumTx GetSigners

* ante: remove EthIntrinsicGasDecorator in favor of EthGasConsumeDecorator

* migrate errors

app/ante/ante.go

@@ -1,9 +1,6 @@
 package ante
 
 import (
-	"fmt"
-	"math/big"
-
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	"github.com/cosmos/cosmos-sdk/x/auth"
@@ -11,11 +8,8 @@ import (
 	"github.com/cosmos/cosmos-sdk/x/auth/types"
 
 	"github.com/cosmos/ethermint/crypto"
-	emint "github.com/cosmos/ethermint/types"
 	evmtypes "github.com/cosmos/ethermint/x/evm/types"
 
-	ethcore "github.com/ethereum/go-ethereum/core"
-
 	tmcrypto "github.com/tendermint/tendermint/crypto"
 )
 
@@ -34,10 +28,10 @@ func NewAnteHandler(ak auth.AccountKeeper, sk types.SupplyKeeper) sdk.AnteHandle
 	return func(
 		ctx sdk.Context, tx sdk.Tx, sim bool,
 	) (newCtx sdk.Context, err error) {
-
+		var anteHandler sdk.AnteHandler
-		switch castTx := tx.(type) {
+		switch tx.(type) {
 		case auth.StdTx:
-			stdAnte := sdk.ChainAnteDecorators(
+			anteHandler = sdk.ChainAnteDecorators(
 				authante.NewSetUpContextDecorator(), // outermost AnteDecorator. SetUpContext must be called first
 				authante.NewMempoolFeeDecorator(),
 				authante.NewValidateBasicDecorator(),
@@ -51,14 +45,21 @@ func NewAnteHandler(ak auth.AccountKeeper, sk types.SupplyKeeper) sdk.AnteHandle
 				authante.NewIncrementSequenceDecorator(ak), // innermost AnteDecorator
 			)
 
-			return stdAnte(ctx, tx, sim)
-
 		case evmtypes.MsgEthereumTx:
-			return ethAnteHandler(ctx, ak, sk, &castTx, sim)
+			anteHandler = sdk.ChainAnteDecorators(
-
+				NewEthSetupContextDecorator(), // outermost AnteDecorator. EthSetUpContext must be called first
+				NewEthMempoolFeeDecorator(),
+				NewEthSigVerificationDecorator(),
+				NewAccountVerificationDecorator(ak),
+				NewNonceVerificationDecorator(ak),
+				NewEthGasConsumeDecorator(ak, sk),
+				NewIncrementSenderSequenceDecorator(ak), // innermost AnteDecorator.
+			)
 		default:
 			return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
 		}
+
+		return anteHandler(ctx, tx, sim)
 	}
 }
 
@@ -78,237 +79,3 @@ func sigGasConsumer(
 		return sdkerrors.Wrapf(sdkerrors.ErrInvalidPubKey, "unrecognized public key type: %T", pubkey)
 	}
 }
-
-// ----------------------------------------------------------------------------
-// Ethereum Ante Handler
-
-// ethAnteHandler defines an internal ante handler for an Ethereum transaction
-// ethTxMsg. During CheckTx, the transaction is passed through a series of
-// pre-message execution validation checks such as signature and account
-// verification in addition to minimum fees being checked. Otherwise, during
-// DeliverTx, the transaction is simply passed to the EVM which will also
-// perform the same series of checks. The distinction is made in CheckTx to
-// prevent spam and DoS attacks.
-func ethAnteHandler(
-	ctx sdk.Context, ak auth.AccountKeeper, sk types.SupplyKeeper,
-	ethTxMsg *evmtypes.MsgEthereumTx, sim bool,
-) (newCtx sdk.Context, err error) {
-
-	var senderAddr sdk.AccAddress
-
-	// This is done to ignore costs in Ante handler checks
-	ctx = ctx.WithBlockGasMeter(sdk.NewInfiniteGasMeter())
-
-	if ctx.IsCheckTx() {
-		// Only perform pre-message (Ethereum transaction) execution validation
-		// during CheckTx. Otherwise, during DeliverTx the EVM will handle them.
-		if senderAddr, err = validateEthTxCheckTx(ctx, ak, ethTxMsg); err != nil {
-			return ctx, err
-		}
-	} else {
-		// This is still currently needed to retrieve the sender address
-		if senderAddr, err = validateSignature(ctx, ethTxMsg); err != nil {
-			return ctx, err
-		}
-
-		// Explicit nonce check is also needed in case of multiple txs with same nonce not being handled
-		if err := checkNonce(ctx, ak, ethTxMsg, senderAddr); err != nil {
-			return ctx, err
-		}
-	}
-
-	// Recover and catch out of gas error
-	defer func() {
-		if r := recover(); r != nil {
-			switch rType := r.(type) {
-			case sdk.ErrorOutOfGas:
-				err = sdkerrors.Wrapf(
-					sdkerrors.ErrOutOfGas,
-					"out of gas in location: %v; gasUsed: %d",
-					rType.Descriptor, ctx.GasMeter().GasConsumed(),
-				)
-			default:
-				panic(r)
-			}
-		}
-	}()
-
-	// Fetch sender account from signature
-	senderAcc, err := auth.GetSignerAcc(ctx, ak, senderAddr)
-	if err != nil {
-		return ctx, err
-	}
-
-	// Charge sender for gas up to limit
-	if ethTxMsg.Data.GasLimit != 0 {
-		// Cost calculates the fees paid to validators based on gas limit and price
-		cost := new(big.Int).Mul(ethTxMsg.Data.Price, new(big.Int).SetUint64(ethTxMsg.Data.GasLimit))
-
-		feeAmt := sdk.NewCoins(
-			sdk.NewCoin(emint.DenomDefault, sdk.NewIntFromBigInt(cost)),
-		)
-
-		err = auth.DeductFees(sk, ctx, senderAcc, feeAmt)
-		if err != nil {
-			return ctx, err
-		}
-	}
-
-	// Set gas meter after ante handler to ignore gaskv costs
-	newCtx = auth.SetGasMeter(sim, ctx, ethTxMsg.Data.GasLimit)
-
-	gas, _ := ethcore.IntrinsicGas(ethTxMsg.Data.Payload, ethTxMsg.To() == nil, true)
-	newCtx.GasMeter().ConsumeGas(gas, "eth intrinsic gas")
-
-	// Increment sequence of sender
-	acc := ak.GetAccount(ctx, senderAddr)
-	if err := acc.SetSequence(acc.GetSequence() + 1); err != nil {
-		panic(err)
-	}
-	ak.SetAccount(ctx, acc)
-
-	return newCtx, nil
-}
-
-func validateEthTxCheckTx(
-	ctx sdk.Context, ak auth.AccountKeeper, ethTxMsg *evmtypes.MsgEthereumTx,
-) (sdk.AccAddress, error) {
-	// Validate sufficient fees have been provided that meet a minimum threshold
-	// defined by the proposer (for mempool purposes during CheckTx).
-	if err := ensureSufficientMempoolFees(ctx, ethTxMsg); err != nil {
-		return nil, err
-	}
-
-	// validate enough intrinsic gas
-	if err := validateIntrinsicGas(ethTxMsg); err != nil {
-		return nil, err
-	}
-
-	signer, err := validateSignature(ctx, ethTxMsg)
-	if err != nil {
-		return nil, err
-	}
-
-	// validate account (nonce and balance checks)
-	if err := validateAccount(ctx, ak, ethTxMsg, signer); err != nil {
-		return nil, err
-	}
-
-	return sdk.AccAddress(signer.Bytes()), nil
-}
-
-// Validates signature and returns sender address
-func validateSignature(ctx sdk.Context, ethTxMsg *evmtypes.MsgEthereumTx) (sdk.AccAddress, error) {
-	// parse the chainID from a string to a base-10 integer
-	chainID, ok := new(big.Int).SetString(ctx.ChainID(), 10)
-	if !ok {
-		return nil, sdkerrors.Wrap(emint.ErrInvalidChainID, ctx.ChainID())
-	}
-
-	// validate sender/signature
-	signer, err := ethTxMsg.VerifySig(chainID)
-	if err != nil {
-		return nil, sdkerrors.Wrap(err, "signature verification failed")
-	}
-
-	return sdk.AccAddress(signer.Bytes()), nil
-}
-
-// validateIntrinsicGas validates that the Ethereum tx message has enough to
-// cover intrinsic gas. Intrinsic gas for a transaction is the amount of gas
-// that the transaction uses before the transaction is executed. The gas is a
-// constant value of 21000 plus any cost inccured by additional bytes of data
-// supplied with the transaction.
-func validateIntrinsicGas(ethTxMsg *evmtypes.MsgEthereumTx) error {
-	gas, err := ethcore.IntrinsicGas(ethTxMsg.Data.Payload, ethTxMsg.To() == nil, true)
-	if err != nil {
-		return sdkerrors.Wrap(err, "failed to compute intrinsic gas cost")
-	}
-
-	if ethTxMsg.Data.GasLimit < gas {
-		return fmt.Errorf(
-			"intrinsic gas too low: %d < %d", ethTxMsg.Data.GasLimit, gas,
-		)
-	}
-
-	return nil
-}
-
-// validateAccount validates the account nonce and that the account has enough
-// funds to cover the tx cost.
-func validateAccount(
-	ctx sdk.Context, ak auth.AccountKeeper, ethTxMsg *evmtypes.MsgEthereumTx, signer sdk.AccAddress,
-) error {
-
-	acc := ak.GetAccount(ctx, signer)
-
-	// on InitChain make sure account number == 0
-	if ctx.BlockHeight() == 0 && acc.GetAccountNumber() != 0 {
-		return sdkerrors.Wrapf(
-			sdkerrors.ErrInvalidSequence,
-			"invalid account number for height zero (got %d)", acc.GetAccountNumber(),
-		)
-	}
-
-	// Validate nonce is correct
-	if err := checkNonce(ctx, ak, ethTxMsg, signer); err != nil {
-		return err
-	}
-
-	// validate sender has enough funds
-	balance := acc.GetCoins().AmountOf(emint.DenomDefault)
-	if balance.BigInt().Cmp(ethTxMsg.Cost()) < 0 {
-		return sdkerrors.Wrapf(
-			sdkerrors.ErrInsufficientFunds,
-			"%s < %s%s", balance.String(), ethTxMsg.Cost().String(), emint.DenomDefault,
-		)
-	}
-
-	return nil
-}
-
-func checkNonce(
-	ctx sdk.Context, ak auth.AccountKeeper, ethTxMsg *evmtypes.MsgEthereumTx, signer sdk.AccAddress,
-) error {
-	acc := ak.GetAccount(ctx, signer)
-	// Validate the transaction nonce is valid (equivalent to the sender account’s
-	// current nonce).
-	seq := acc.GetSequence()
-	if ethTxMsg.Data.AccountNonce != seq {
-		return sdkerrors.Wrapf(
-			sdkerrors.ErrInvalidSequence,
-			"got nonce %d, expected %d", ethTxMsg.Data.AccountNonce, seq,
-		)
-	}
-
-	return nil
-}
-
-// ensureSufficientMempoolFees verifies that enough fees have been provided by the
-// Ethereum transaction that meet the minimum threshold set by the block
-// proposer.
-//
-// NOTE: This should only be ran during a CheckTx mode.
-func ensureSufficientMempoolFees(ctx sdk.Context, ethTxMsg *evmtypes.MsgEthereumTx) error {
-	// fee = GP * GL
-	fee := sdk.NewDecCoinFromCoin(sdk.NewInt64Coin(emint.DenomDefault, ethTxMsg.Fee().Int64()))
-
-	minGasPrices := ctx.MinGasPrices()
-	allGTE := true
-	for _, v := range minGasPrices {
-		if !fee.IsGTE(v) {
-			allGTE = false
-		}
-	}
-
-	// it is assumed that the minimum fees will only include the single valid denom
-	if !ctx.MinGasPrices().IsZero() && !allGTE {
-		// reject the transaction that does not meet the minimum fee
-		return sdkerrors.Wrapf(
-			sdkerrors.ErrInsufficientFee,
-			"got: %q required: %q", fee, ctx.MinGasPrices(),
-		)
-	}
-
-	return nil
-}

app/ante/ante_test.go

@@ -55,7 +55,7 @@ func (suite *AnteTestSuite) TestValidEthTx() {
 	to := ethcmn.BytesToAddress(addr2.Bytes())
 	amt := big.NewInt(32)
 	gas := big.NewInt(20)
-	ethMsg := evmtypes.NewMsgEthereumTx(0, &to, amt, 22000, gas, []byte("test"))
+	ethMsg := evmtypes.NewMsgEthereumTx(0, &to, amt, 34910, gas, []byte("test"))
 
 	tx := newTestEthTx(suite.ctx, ethMsg, priv1)
 	requireValidTx(suite.T(), suite.anteHandler, suite.ctx, tx, false)

app/ante/doc.go

@@ -0,0 +1,11 @@
+/*Package ante defines the SDK auth module's AnteHandler as well as an internal
+AnteHandler for an Ethereum transaction (i.e MsgEthereumTx).
+
+During CheckTx, the transaction is passed through a series of
+pre-message execution validation checks such as signature and account
+verification in addition to minimum fees being checked. Otherwise, during
+DeliverTx, the transaction is simply passed to the EVM which will also
+perform the same series of checks. The distinction is made in CheckTx to
+prevent spam and DoS attacks.
+*/
+package ante

app/ante/eth.go

@@ -0,0 +1,361 @@
+package ante
+
+import (
+	"fmt"
+	"math/big"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+	"github.com/cosmos/cosmos-sdk/x/auth"
+	authante "github.com/cosmos/cosmos-sdk/x/auth/ante"
+	"github.com/cosmos/cosmos-sdk/x/auth/types"
+
+	emint "github.com/cosmos/ethermint/types"
+	evmtypes "github.com/cosmos/ethermint/x/evm/types"
+
+	ethcore "github.com/ethereum/go-ethereum/core"
+)
+
+// EthSetupContextDecorator sets the infinite GasMeter in the Context and wraps
+// the next AnteHandler with a defer clause to recover from any downstream
+// OutOfGas panics in the AnteHandler chain to return an error with information
+// on gas provided and gas used.
+// CONTRACT: Must be first decorator in the chain
+// CONTRACT: Tx must implement GasTx interface
+type EthSetupContextDecorator struct{}
+
+// NewEthSetupContextDecorator creates a new EthSetupContextDecorator
+func NewEthSetupContextDecorator() EthSetupContextDecorator {
+	return EthSetupContextDecorator{}
+}
+
+// AnteHandle sets the infinite gas meter to done to ignore costs in AnteHandler checks.
+// This is undone at the EthGasConsumeDecorator, where the context is set with the
+// ethereum tx GasLimit.
+func (escd EthSetupContextDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	ctx = ctx.WithBlockGasMeter(sdk.NewInfiniteGasMeter())
+
+	// all transactions must implement GasTx
+	gasTx, ok := tx.(authante.GasTx)
+	if !ok {
+		return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be GasTx")
+	}
+
+	// Decorator will catch an OutOfGasPanic caused in the next antehandler
+	// AnteHandlers must have their own defer/recover in order for the BaseApp
+	// to know how much gas was used! This is because the GasMeter is created in
+	// the AnteHandler, but if it panics the context won't be set properly in
+	// runTx's recover call.
+	defer func() {
+		if r := recover(); r != nil {
+			switch rType := r.(type) {
+			case sdk.ErrorOutOfGas:
+				log := fmt.Sprintf(
+					"out of gas in location: %v; gasLimit: %d, gasUsed: %d",
+					rType.Descriptor, gasTx.GetGas(), ctx.GasMeter().GasConsumed(),
+				)
+				err = sdkerrors.Wrap(sdkerrors.ErrOutOfGas, log)
+			default:
+				panic(r)
+			}
+		}
+	}()
+
+	return next(ctx, tx, simulate)
+}
+
+// EthMempoolFeeDecorator validates that sufficient fees have been provided that
+// meet a minimum threshold defined by the proposer (for mempool purposes during CheckTx).
+type EthMempoolFeeDecorator struct{}
+
+// NewEthMempoolFeeDecorator creates a new EthMempoolFeeDecorator
+func NewEthMempoolFeeDecorator() EthMempoolFeeDecorator {
+	return EthMempoolFeeDecorator{}
+}
+
+// AnteHandle verifies that enough fees have been provided by the
+// Ethereum transaction that meet the minimum threshold set by the block
+// proposer.
+//
+// NOTE: This should only be run during a CheckTx mode.
+func (emfd EthMempoolFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	if !ctx.IsCheckTx() {
+		return next(ctx, tx, simulate)
+	}
+
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// fee = GP * GL
+	fee := sdk.NewInt64DecCoin(emint.DenomDefault, msgEthTx.Fee().Int64())
+
+	minGasPrices := ctx.MinGasPrices()
+
+	allGTE := true
+	for _, v := range minGasPrices {
+		if !fee.IsGTE(v) {
+			allGTE = false
+		}
+	}
+
+	// it is assumed that the minimum fees will only include the single valid denom
+	if !ctx.MinGasPrices().IsZero() && !allGTE {
+		// reject the transaction that does not meet the minimum fee
+		return ctx, sdkerrors.Wrap(
+			sdkerrors.ErrInsufficientFee,
+			fmt.Sprintf("insufficient fee, got: %q required: %q", fee, ctx.MinGasPrices()),
+		)
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+// EthSigVerificationDecorator validates an ethereum signature
+type EthSigVerificationDecorator struct{}
+
+// NewEthSigVerificationDecorator creates a new EthSigVerificationDecorator
+func NewEthSigVerificationDecorator() EthSigVerificationDecorator {
+	return EthSigVerificationDecorator{}
+}
+
+// AnteHandle validates the signature and returns sender address
+func (esvd EthSigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// parse the chainID from a string to a base-10 integer
+	chainID, ok := new(big.Int).SetString(ctx.ChainID(), 10)
+	if !ok {
+		return ctx, sdkerrors.Wrap(emint.ErrInvalidChainID, ctx.ChainID())
+	}
+
+	// validate sender/signature
+	// NOTE: signer is retrieved from the transaction on the next AnteDecorator
+	_, err = msgEthTx.VerifySig(chainID)
+	if err != nil {
+		return ctx, sdkerrors.Wrap(sdkerrors.ErrUnauthorized, fmt.Sprintf("signature verification failed"))
+	}
+
+	return next(ctx, msgEthTx, simulate)
+}
+
+// AccountVerificationDecorator validates an account balance checks
+type AccountVerificationDecorator struct {
+	ak auth.AccountKeeper
+}
+
+// NewAccountVerificationDecorator creates a new AccountVerificationDecorator
+func NewAccountVerificationDecorator(ak auth.AccountKeeper) AccountVerificationDecorator {
+	return AccountVerificationDecorator{
+		ak: ak,
+	}
+}
+
+// AnteHandle validates the signature and returns sender address
+func (avd AccountVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	if !ctx.IsCheckTx() {
+		return next(ctx, tx, simulate)
+	}
+
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// sender address should be in the tx cache
+	address := msgEthTx.From()
+	if address == nil {
+		panic("sender address is nil")
+	}
+
+	acc := avd.ak.GetAccount(ctx, address)
+	if acc == nil {
+		return ctx, fmt.Errorf("account %s is nil", address)
+	}
+
+	// on InitChain make sure account number == 0
+	if ctx.BlockHeight() == 0 && acc.GetAccountNumber() != 0 {
+		return ctx, sdkerrors.Wrapf(
+			sdkerrors.ErrInvalidSequence,
+			"invalid account number for height zero (got %d)", acc.GetAccountNumber(),
+		)
+	}
+
+	// validate sender has enough funds
+	balance := acc.GetCoins().AmountOf(emint.DenomDefault)
+	if balance.BigInt().Cmp(msgEthTx.Cost()) < 0 {
+		return ctx, sdkerrors.Wrapf(
+			sdkerrors.ErrInsufficientFunds,
+			"%s < %s%s", balance.String(), msgEthTx.Cost().String(), emint.DenomDefault,
+		)
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+// NonceVerificationDecorator that the nonce matches
+type NonceVerificationDecorator struct {
+	ak auth.AccountKeeper
+}
+
+// NewNonceVerificationDecorator creates a new NonceVerificationDecorator
+func NewNonceVerificationDecorator(ak auth.AccountKeeper) NonceVerificationDecorator {
+	return NonceVerificationDecorator{
+		ak: ak,
+	}
+}
+
+// AnteHandle validates that the transaction nonce is valid (equivalent to the sender account’s
+// current nonce).
+func (nvd NonceVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// sender address should be in the tx cache
+	address := msgEthTx.From()
+	if address == nil {
+		panic("sender address is nil")
+	}
+
+	acc := nvd.ak.GetAccount(ctx, address)
+	if acc == nil {
+		return ctx, fmt.Errorf("account %s is nil", address)
+	}
+
+	seq := acc.GetSequence()
+	if msgEthTx.Data.AccountNonce != seq {
+		return ctx, sdkerrors.Wrap(
+			sdkerrors.ErrInvalidSequence,
+			fmt.Sprintf("invalid nonce; got %d, expected %d", msgEthTx.Data.AccountNonce, seq),
+		)
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+// EthGasConsumeDecorator validates enough intrinsic gas for the transaction and
+// gas consumption.
+type EthGasConsumeDecorator struct {
+	ak auth.AccountKeeper
+	sk types.SupplyKeeper
+}
+
+// NewEthGasConsumeDecorator creates a new EthGasConsumeDecorator
+func NewEthGasConsumeDecorator(ak auth.AccountKeeper, sk types.SupplyKeeper) EthGasConsumeDecorator {
+	return EthGasConsumeDecorator{
+		ak: ak,
+		sk: sk,
+	}
+}
+
+// AnteHandle validates that the Ethereum tx message has enough to cover intrinsic gas
+// (during CheckTx only) and that the sender has enough balance to pay for the gas cost.
+//
+// Intrinsic gas for a transaction is the amount of gas
+// that the transaction uses before the transaction is executed. The gas is a
+// constant value of 21000 plus any cost inccured by additional bytes of data
+// supplied with the transaction.
+func (egcd EthGasConsumeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// sender address should be in the tx cache
+	address := msgEthTx.From()
+	if address == nil {
+		panic("sender address is nil")
+	}
+
+	// Fetch sender account from signature
+	senderAcc, err := auth.GetSignerAcc(ctx, egcd.ak, address)
+	if err != nil {
+		return ctx, err
+	}
+
+	if senderAcc == nil {
+		return ctx, fmt.Errorf("sender account %s is nil", address)
+	}
+
+	gasLimit := msgEthTx.GetGas()
+	gas, err := ethcore.IntrinsicGas(msgEthTx.Data.Payload, msgEthTx.To() == nil, true)
+	if err != nil {
+		return ctx, sdkerrors.Wrap(err, "failed to compute intrinsic gas cost")
+	}
+
+	// intrinsic gas verification during CheckTx
+	if ctx.IsCheckTx() && gasLimit < gas {
+		return ctx, fmt.Errorf("intrinsic gas too low: %d < %d", gasLimit, gas)
+	}
+
+	// Charge sender for gas up to limit
+	if gasLimit != 0 {
+		// Cost calculates the fees paid to validators based on gas limit and price
+		cost := new(big.Int).Mul(msgEthTx.Data.Price, new(big.Int).SetUint64(gasLimit))
+
+		feeAmt := sdk.NewCoins(
+			sdk.NewCoin(emint.DenomDefault, sdk.NewIntFromBigInt(cost)),
+		)
+
+		err = auth.DeductFees(egcd.sk, ctx, senderAcc, feeAmt)
+		if err != nil {
+			return ctx, err
+		}
+	}
+
+	// Set gas meter after ante handler to ignore gaskv costs
+	newCtx = auth.SetGasMeter(simulate, ctx, gasLimit)
+	newCtx.GasMeter().ConsumeGas(gas, "eth intrinsic gas")
+
+	return next(newCtx, tx, simulate)
+}
+
+// IncrementSenderSequenceDecorator increments the sequence of the signers. The
+// main difference with the SDK's IncrementSequenceDecorator is that the MsgEthereumTx
+// doesn't implement the SigVerifiableTx interface.
+//
+// CONTRACT: must be called after msg.VerifySig in order to cache the sender address.
+type IncrementSenderSequenceDecorator struct {
+	ak auth.AccountKeeper
+}
+
+// NewIncrementSenderSequenceDecorator creates a new IncrementSenderSequenceDecorator.
+func NewIncrementSenderSequenceDecorator(ak auth.AccountKeeper) IncrementSenderSequenceDecorator {
+	return IncrementSenderSequenceDecorator{
+		ak: ak,
+	}
+}
+
+// AnteHandle handles incrementing the sequence of the sender.
+func (issd IncrementSenderSequenceDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) {
+	// no need to increment sequence on RecheckTx
+	if ctx.IsReCheckTx() && !simulate {
+		return next(ctx, tx, simulate)
+	}
+
+	// get and set account must be called with an infinite gas meter in order to prevent
+	// additional gas from being deducted.
+	oldCtx := ctx.WithBlockGasMeter(sdk.NewInfiniteGasMeter())
+
+	msgEthTx, ok := tx.(evmtypes.MsgEthereumTx)
+	if !ok {
+		return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type: %T", tx)
+	}
+
+	// increment sequence of all signers
+	for _, addr := range msgEthTx.GetSigners() {
+		acc := issd.ak.GetAccount(oldCtx, addr)
+		if err := acc.SetSequence(acc.GetSequence() + 1); err != nil {
+			panic(err)
+		}
+		issd.ak.SetAccount(oldCtx, acc)
+	}
+
+	return next(ctx, tx, simulate)
+}

app/export.go

@@ -8,12 +8,18 @@ import (
 	tmtypes "github.com/tendermint/tendermint/types"
 
 	"github.com/cosmos/cosmos-sdk/codec"
+	"github.com/cosmos/cosmos-sdk/simapp"
 	sdk "github.com/cosmos/cosmos-sdk/types"
 	"github.com/cosmos/cosmos-sdk/x/slashing"
 	"github.com/cosmos/cosmos-sdk/x/staking"
 	"github.com/cosmos/cosmos-sdk/x/staking/exported"
 )
 
+// NewDefaultGenesisState generates the default state for the application.
+func NewDefaultGenesisState() simapp.GenesisState {
+	return ModuleBasics.DefaultGenesis()
+}
+
 // ExportAppStateAndValidators exports the state of the application for a genesis
 // file.
 func (app *EthermintApp) ExportAppStateAndValidators(

app/test_helpers.go

@@ -6,16 +6,16 @@ import (
 	dbm "github.com/tendermint/tm-db"
 
 	"github.com/cosmos/cosmos-sdk/codec"
-	"github.com/cosmos/cosmos-sdk/simapp"
 )
 
 // Setup initializes a new EthermintApp. A Nop logger is set in EthermintApp.
 func Setup(isCheckTx bool) *EthermintApp {
 	db := dbm.NewMemDB()
 	app := NewEthermintApp(log.NewNopLogger(), db, nil, true, 0)
+
 	if !isCheckTx {
 		// init chain must be called to stop deliverState from being nil
-		genesisState := simapp.NewDefaultGenesisState()
+		genesisState := NewDefaultGenesisState()
 		stateBytes, err := codec.MarshalJSONIndent(app.Codec(), genesisState)
 		if err != nil {
 			panic(err)

x/evm/types/msg.go

@@ -157,10 +157,13 @@ func (msg MsgEthereumTx) GetMsgs() []sdk.Msg {
 // GetSigners returns the expected signers for an Ethereum transaction message.
 // For such a message, there should exist only a single 'signer'.
 //
-// NOTE: This method cannot be used as a chain ID is needed to recover the signer
+// NOTE: This method panics if 'VerifySig' hasn't been called first.
-// from the signature. Use 'VerifySig' instead.
 func (msg MsgEthereumTx) GetSigners() []sdk.AccAddress {
-	panic("must use 'VerifySig' with a chain ID to get the signer")
+	sender := msg.From()
+	if sender.Empty() {
+		panic("must use 'VerifySig' with a chain ID to get the signer")
+	}
+	return []sdk.AccAddress{sender}
 }
 
 // GetSignBytes returns the Amino bytes of an Ethereum transaction message used
@@ -271,11 +274,9 @@ func (msg *MsgEthereumTx) VerifySig(chainID *big.Int) (ethcmn.Address, error) {
 	return sender, nil
 }
 
-// Cost returns amount + gasprice * gaslimit.
+// GetGas implements the GasTx interface. It returns the GasLimit of the transaction.
-func (msg MsgEthereumTx) Cost() *big.Int {
+func (msg MsgEthereumTx) GetGas() uint64 {
-	total := msg.Fee()
+	return msg.Data.GasLimit
-	total.Add(total, msg.Data.Amount)
-	return total
 }
 
 // Fee returns gasprice * gaslimit.
@@ -288,6 +289,30 @@ func (msg *MsgEthereumTx) ChainID() *big.Int {
 	return deriveChainID(msg.Data.V)
 }
 
+// Cost returns amount + gasprice * gaslimit.
+func (msg MsgEthereumTx) Cost() *big.Int {
+	total := msg.Fee()
+	total.Add(total, msg.Data.Amount)
+	return total
+}
+
+// From loads the ethereum sender address from the sigcache and returns an
+// sdk.AccAddress from its bytes
+func (msg *MsgEthereumTx) From() sdk.AccAddress {
+	sc := msg.from.Load()
+	if sc == nil {
+		return nil
+	}
+
+	sigCache := sc.(sigCache)
+
+	if len(sigCache.from.Bytes()) == 0 {
+		return nil
+	}
+
+	return sdk.AccAddress(sigCache.from.Bytes())
+}
+
 // deriveChainID derives the chain id from the given v parameter
 func deriveChainID(v *big.Int) *big.Int {
 	if v.BitLen() <= 64 {