package ante import ( "errors" "math/big" sdk "github.com/cosmos/cosmos-sdk/types" sdkerrors "github.com/cosmos/cosmos-sdk/types/errors" tx "github.com/cosmos/cosmos-sdk/types/tx" authante "github.com/cosmos/cosmos-sdk/x/auth/ante" ethermint "github.com/tharsis/ethermint/types" evmkeeper "github.com/tharsis/ethermint/x/evm/keeper" evmtypes "github.com/tharsis/ethermint/x/evm/types" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/core" ethtypes "github.com/ethereum/go-ethereum/core/types" "github.com/ethereum/go-ethereum/core/vm" ) // EVMKeeper defines the expected keeper interface used on the Eth AnteHandler type EVMKeeper interface { vm.StateDB ChainID() *big.Int GetParams(ctx sdk.Context) evmtypes.Params WithContext(ctx sdk.Context) ResetRefundTransient(ctx sdk.Context) NewEVM(msg core.Message, cfg *evmtypes.EVMConfig, tracer vm.Tracer) *vm.EVM GetCodeHash(addr common.Address) common.Hash DeductTxCostsFromUserBalance( ctx sdk.Context, msgEthTx evmtypes.MsgEthereumTx, txData evmtypes.TxData, denom string, homestead, istanbul, london bool, ) (sdk.Coins, error) } type protoTxProvider interface { GetProtoTx() *tx.Tx } // EthSigVerificationDecorator validates an ethereum signatures type EthSigVerificationDecorator struct { evmKeeper EVMKeeper } // NewEthSigVerificationDecorator creates a new EthSigVerificationDecorator func NewEthSigVerificationDecorator(ek EVMKeeper) EthSigVerificationDecorator { return EthSigVerificationDecorator{ evmKeeper: ek, } } // AnteHandle validates checks that the registered chain id is the same as the one on the message, and // that the signer address matches the one defined on the message. // It's not skipped for RecheckTx, because it set `From` address which is critical from other ante handler to work. // Failure in RecheckTx will prevent tx to be included into block, especially when CheckTx succeed, in which case user // won't see the error message. func (esvd EthSigVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) { if tx == nil || len(tx.GetMsgs()) != 1 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "only 1 ethereum msg supported per tx") } chainID := esvd.evmKeeper.ChainID() params := esvd.evmKeeper.GetParams(ctx) ethCfg := params.ChainConfig.EthereumConfig(chainID) blockNum := big.NewInt(ctx.BlockHeight()) signer := ethtypes.MakeSigner(ethCfg, blockNum) msg := tx.GetMsgs()[0] msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } sender, err := signer.Sender(msgEthTx.AsTransaction()) if err != nil { return ctx, sdkerrors.Wrapf( sdkerrors.ErrorInvalidSigner, "couldn't retrieve sender address ('%s') from the ethereum transaction: %s", msgEthTx.From, err.Error(), ) } // set up the sender to the transaction field if not already msgEthTx.From = sender.Hex() return next(ctx, msgEthTx, simulate) } // EthAccountVerificationDecorator validates an account balance checks type EthAccountVerificationDecorator struct { ak evmtypes.AccountKeeper bankKeeper evmtypes.BankKeeper evmKeeper EVMKeeper } // NewEthAccountVerificationDecorator creates a new EthAccountVerificationDecorator func NewEthAccountVerificationDecorator(ak evmtypes.AccountKeeper, bankKeeper evmtypes.BankKeeper, ek EVMKeeper) EthAccountVerificationDecorator { return EthAccountVerificationDecorator{ ak: ak, bankKeeper: bankKeeper, evmKeeper: ek, } } // AnteHandle validates checks that the sender balance is greater than the total transaction cost. // The account will be set to store if it doesn't exis, i.e cannot be found on store. // This AnteHandler decorator will fail if: // - any of the msgs is not a MsgEthereumTx // - from address is empty // - account balance is lower than the transaction cost func (avd EthAccountVerificationDecorator) 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) } avd.evmKeeper.WithContext(ctx) evmDenom := avd.evmKeeper.GetParams(ctx).EvmDenom for i, msg := range tx.GetMsgs() { msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } txData, err := evmtypes.UnpackTxData(msgEthTx.Data) if err != nil { return ctx, sdkerrors.Wrapf(err, "failed to unpack tx data any for tx %d", i) } // sender address should be in the tx cache from the previous AnteHandle call from := msgEthTx.GetFrom() if from.Empty() { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidAddress, "from address cannot be empty") } // check whether the sender address is EOA fromAddr := common.BytesToAddress(from) codeHash := avd.evmKeeper.GetCodeHash(fromAddr) if codeHash != common.BytesToHash(evmtypes.EmptyCodeHash) { return ctx, sdkerrors.Wrapf(sdkerrors.ErrInvalidType, "the sender is not EOA: address <%v>, codeHash <%s>", fromAddr, codeHash) } acc := avd.ak.GetAccount(ctx, from) if acc == nil { acc = avd.ak.NewAccountWithAddress(ctx, from) avd.ak.SetAccount(ctx, acc) } if err := evmkeeper.CheckSenderBalance(ctx, avd.bankKeeper, from, txData, evmDenom); err != nil { return ctx, sdkerrors.Wrap(err, "failed to check sender balance") } } // recover the original gas meter avd.evmKeeper.WithContext(ctx) return next(ctx, tx, simulate) } // EthNonceVerificationDecorator checks that the account nonce from the transaction matches // the sender account sequence. type EthNonceVerificationDecorator struct { ak evmtypes.AccountKeeper } // NewEthNonceVerificationDecorator creates a new EthNonceVerificationDecorator func NewEthNonceVerificationDecorator(ak evmtypes.AccountKeeper) EthNonceVerificationDecorator { return EthNonceVerificationDecorator{ ak: ak, } } // AnteHandle validates that the transaction nonces are valid and equivalent to the sender account’s // current nonce. func (nvd EthNonceVerificationDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) { // no need to check the nonce on ReCheckTx if ctx.IsReCheckTx() { return next(ctx, tx, simulate) } for _, msg := range tx.GetMsgs() { msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } // sender address should be in the tx cache from the previous AnteHandle call seq, err := nvd.ak.GetSequence(ctx, msgEthTx.GetFrom()) if err != nil { return ctx, sdkerrors.Wrapf(err, "sequence not found for address %s", msgEthTx.From) } txData, err := evmtypes.UnpackTxData(msgEthTx.Data) if err != nil { return ctx, sdkerrors.Wrap(err, "failed to unpack tx data") } // if multiple transactions are submitted in succession with increasing nonces, // all will be rejected except the first, since the first needs to be included in a block // before the sequence increments if txData.GetNonce() != seq { return ctx, sdkerrors.Wrapf( sdkerrors.ErrInvalidSequence, "invalid nonce; got %d, expected %d", txData.GetNonce(), seq, ) } } return next(ctx, tx, simulate) } // EthGasConsumeDecorator validates enough intrinsic gas for the transaction and // gas consumption. type EthGasConsumeDecorator struct { evmKeeper EVMKeeper } // NewEthGasConsumeDecorator creates a new EthGasConsumeDecorator func NewEthGasConsumeDecorator( evmKeeper EVMKeeper, ) EthGasConsumeDecorator { return EthGasConsumeDecorator{ evmKeeper: evmKeeper, } } // 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 plus any cost inccured by additional bytes // of data supplied with the transaction. // // This AnteHandler decorator will fail if: // - the transaction contains more than one message // - the message is not a MsgEthereumTx // - sender account cannot be found // - transaction's gas limit is lower than the intrinsic gas // - user doesn't have enough balance to deduct the transaction fees (gas_limit * gas_price) // - transaction or block gas meter runs out of gas func (egcd EthGasConsumeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) { // reset the refund gas value in the keeper for the current transaction egcd.evmKeeper.ResetRefundTransient(ctx) params := egcd.evmKeeper.GetParams(ctx) ethCfg := params.ChainConfig.EthereumConfig(egcd.evmKeeper.ChainID()) blockHeight := big.NewInt(ctx.BlockHeight()) homestead := ethCfg.IsHomestead(blockHeight) istanbul := ethCfg.IsIstanbul(blockHeight) london := ethCfg.IsLondon(blockHeight) evmDenom := params.EvmDenom var events sdk.Events for _, msg := range tx.GetMsgs() { msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } txData, err := evmtypes.UnpackTxData(msgEthTx.Data) if err != nil { return ctx, sdkerrors.Wrap(err, "failed to unpack tx data") } fees, err := egcd.evmKeeper.DeductTxCostsFromUserBalance( ctx, *msgEthTx, txData, evmDenom, homestead, istanbul, london, ) if err != nil { return ctx, sdkerrors.Wrapf(err, "failed to deduct transaction costs from user balance") } events = append(events, sdk.NewEvent(sdk.EventTypeTx, sdk.NewAttribute(sdk.AttributeKeyFee, fees.String()))) } // TODO: change to typed events ctx.EventManager().EmitEvents(events) // TODO: deprecate after https://github.com/cosmos/cosmos-sdk/issues/9514 is fixed on SDK blockGasLimit := ethermint.BlockGasLimit(ctx) // NOTE: safety check if blockGasLimit > 0 { // generate a copy of the gas pool (i.e block gas meter) to see if we've run out of gas for this block // if current gas consumed is greater than the limit, this funcion panics and the error is recovered on the Baseapp gasPool := sdk.NewGasMeter(blockGasLimit) gasPool.ConsumeGas(ctx.GasMeter().GasConsumedToLimit(), "gas pool check") } // we know that we have enough gas on the pool to cover the intrinsic gas // set up the updated context to the evm Keeper egcd.evmKeeper.WithContext(ctx) return next(ctx, tx, simulate) } // CanTransferDecorator checks if the sender is allowed to transfer funds according to the EVM block // context rules. type CanTransferDecorator struct { evmKeeper EVMKeeper feemarketKeeper evmtypes.FeeMarketKeeper } // NewCanTransferDecorator creates a new CanTransferDecorator instance. func NewCanTransferDecorator(evmKeeper EVMKeeper, fmk evmtypes.FeeMarketKeeper) CanTransferDecorator { return CanTransferDecorator{ evmKeeper: evmKeeper, feemarketKeeper: fmk, } } // AnteHandle creates an EVM from the message and calls the BlockContext CanTransfer function to // see if the address can execute the transaction. func (ctd CanTransferDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) { ctd.evmKeeper.WithContext(ctx) params := ctd.evmKeeper.GetParams(ctx) feeMktParams := ctd.feemarketKeeper.GetParams(ctx) ethCfg := params.ChainConfig.EthereumConfig(ctd.evmKeeper.ChainID()) signer := ethtypes.MakeSigner(ethCfg, big.NewInt(ctx.BlockHeight())) for _, msg := range tx.GetMsgs() { msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } var baseFee *big.Int if evmtypes.IsLondon(ethCfg, ctx.BlockHeight()) && !feeMktParams.NoBaseFee { baseFee = ctd.feemarketKeeper.GetBaseFee(ctx) } coreMsg, err := msgEthTx.AsMessage(signer, baseFee) if err != nil { return ctx, sdkerrors.Wrapf( err, "failed to create an ethereum core.Message from signer %T", signer, ) } // NOTE: pass in an empty coinbase address and nil tracer as we don't need them for the check below cfg := &evmtypes.EVMConfig{ ChainConfig: ethCfg, Params: params, CoinBase: common.Address{}, BaseFee: baseFee, } evm := ctd.evmKeeper.NewEVM(coreMsg, cfg, evmtypes.NewNoOpTracer()) // check that caller has enough balance to cover asset transfer for **topmost** call // NOTE: here the gas consumed is from the context with the infinite gas meter if coreMsg.Value().Sign() > 0 && !evm.Context.CanTransfer(ctd.evmKeeper, coreMsg.From(), coreMsg.Value()) { return ctx, sdkerrors.Wrapf( sdkerrors.ErrInsufficientFunds, "failed to transfer %s from address %s using the EVM block context transfer function", coreMsg.Value(), coreMsg.From(), ) } if evmtypes.IsLondon(ethCfg, ctx.BlockHeight()) && !feeMktParams.NoBaseFee && baseFee == nil { return ctx, sdkerrors.Wrap(evmtypes.ErrInvalidBaseFee, "base fee is supported but evm block context value is nil") } if evmtypes.IsLondon(ethCfg, ctx.BlockHeight()) && !feeMktParams.NoBaseFee && baseFee != nil && coreMsg.GasFeeCap().Cmp(baseFee) < 0 { return ctx, sdkerrors.Wrapf(evmtypes.ErrInvalidBaseFee, "max fee per gas less than block base fee (%s < %s)", coreMsg.GasFeeCap(), baseFee) } } ctd.evmKeeper.WithContext(ctx) // set the original gas meter return next(ctx, tx, simulate) } // EthIncrementSenderSequenceDecorator increments the sequence of the signers. type EthIncrementSenderSequenceDecorator struct { ak evmtypes.AccountKeeper } // NewEthIncrementSenderSequenceDecorator creates a new EthIncrementSenderSequenceDecorator. func NewEthIncrementSenderSequenceDecorator(ak evmtypes.AccountKeeper) EthIncrementSenderSequenceDecorator { return EthIncrementSenderSequenceDecorator{ ak: ak, } } // AnteHandle handles incrementing the sequence of the signer (i.e sender). If the transaction is a // contract creation, the nonce will be incremented during the transaction execution and not within // this AnteHandler decorator. func (issd EthIncrementSenderSequenceDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) { for _, msg := range tx.GetMsgs() { msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } txData, err := evmtypes.UnpackTxData(msgEthTx.Data) if err != nil { return ctx, sdkerrors.Wrap(err, "failed to unpack tx data") } // NOTE: on contract creation, the nonce is incremented within the EVM Create function during tx execution // and not previous to the state transition ¯\_(ツ)_/¯ if txData.GetTo() == nil { // contract creation, don't increment sequence on AnteHandler but on tx execution // continue to the next item continue } // increment sequence of all signers for _, addr := range msg.GetSigners() { acc := issd.ak.GetAccount(ctx, addr) if acc == nil { return ctx, sdkerrors.Wrapf( sdkerrors.ErrUnknownAddress, "account %s (%s) is nil", common.BytesToAddress(addr.Bytes()), addr, ) } if err := acc.SetSequence(acc.GetSequence() + 1); err != nil { return ctx, sdkerrors.Wrapf(err, "failed to set sequence to %d", acc.GetSequence()+1) } issd.ak.SetAccount(ctx, acc) } } // set the original gas meter return next(ctx, tx, simulate) } // EthValidateBasicDecorator is adapted from ValidateBasicDecorator from cosmos-sdk, it ignores ErrNoSignatures type EthValidateBasicDecorator struct { evmKeeper EVMKeeper } // NewEthValidateBasicDecorator creates a new EthValidateBasicDecorator func NewEthValidateBasicDecorator(ek EVMKeeper) EthValidateBasicDecorator { return EthValidateBasicDecorator{ evmKeeper: ek, } } // AnteHandle handles basic validation of tx func (vbd EthValidateBasicDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (sdk.Context, error) { // no need to validate basic on recheck tx, call next antehandler if ctx.IsReCheckTx() { return next(ctx, tx, simulate) } err := tx.ValidateBasic() // ErrNoSignatures is fine with eth tx if err != nil && !errors.Is(err, sdkerrors.ErrNoSignatures) { return ctx, sdkerrors.Wrap(err, "tx basic validation failed") } // For eth type cosmos tx, some fields should be veified as zero values, // since we will only verify the signature against the hash of the MsgEthereumTx.Data if wrapperTx, ok := tx.(protoTxProvider); ok { protoTx := wrapperTx.GetProtoTx() body := protoTx.Body if body.Memo != "" || body.TimeoutHeight != uint64(0) || len(body.NonCriticalExtensionOptions) > 0 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx body Memo TimeoutHeight NonCriticalExtensionOptions should be empty") } if len(body.ExtensionOptions) != 1 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx length of ExtensionOptions should be 1") } if len(protoTx.GetMsgs()) != 1 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "only 1 ethereum msg supported per tx") } msg := protoTx.GetMsgs()[0] msgEthTx, ok := msg.(*evmtypes.MsgEthereumTx) if !ok { return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid transaction type %T, expected %T", tx, (*evmtypes.MsgEthereumTx)(nil)) } ethGasLimit := msgEthTx.GetGas() txData, err := evmtypes.UnpackTxData(msgEthTx.Data) if err != nil { return ctx, sdkerrors.Wrap(err, "failed to unpack MsgEthereumTx Data") } params := vbd.evmKeeper.GetParams(ctx) ethFeeAmount := sdk.Coins{sdk.NewCoin(params.EvmDenom, sdk.NewIntFromBigInt(txData.Fee()))} authInfo := protoTx.AuthInfo if len(authInfo.SignerInfos) > 0 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx AuthInfo SignerInfos should be empty") } if authInfo.Fee.Payer != "" || authInfo.Fee.Granter != "" { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx AuthInfo Fee payer and granter should be empty") } if !authInfo.Fee.Amount.IsEqual(ethFeeAmount) { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "invalid eth tx AuthInfo Fee Amount") } if authInfo.Fee.GasLimit != ethGasLimit { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "invalid eth tx AuthInfo Fee GasLimit") } sigs := protoTx.Signatures if len(sigs) > 0 { return ctx, sdkerrors.Wrap(sdkerrors.ErrInvalidRequest, "for eth tx Signatures should be empty") } } return next(ctx, tx, simulate) } // EthSetupContextDecorator is adapted from SetUpContextDecorator from cosmos-sdk, it ignores gas consumption // by setting the gas meter to infinite type EthSetupContextDecorator struct{} func NewEthSetUpContextDecorator() EthSetupContextDecorator { return EthSetupContextDecorator{} } func (esc EthSetupContextDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) { // all transactions must implement GasTx _, ok := tx.(authante.GasTx) if !ok { return newCtx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be GasTx") } newCtx = ctx.WithGasMeter(sdk.NewInfiniteGasMeter()) return next(newCtx, tx, simulate) }