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feemarket: global MinGasPrice parameter (#1104)
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* Add min_gas_price to feemarket params

* Add MinGasPriceDecorators

* feemarket integration tests for MinGasPrice

* Restructure integration tests

* Simplify integration tests context

We use DeliverTx context to set up the app, otherwise not all settings are initialized.
We test CheckTx with `s.app.BaseApp.CheckTx(req)`, which uses the `CheckTx` mode and context.

* Update MinGasPrice spec in feemarket module

* reorder ethermint module order for initializing genesis

* feemarket migrations for adding MinGasPrice param

* update changelog

* Additional unit tests for MinGasPrice = 0, tx gas price > 0 (PR review)

evmos/ethermint#1104 (comment)

* Use 0 MinGasPrice for transaction simulations

* Fix duplicate registration of feemarket GenesisState and Params (PR review)

evmos/ethermint#1104 (comment)
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T0psecurity committed May 31, 2022
1 parent 8df0b23 commit 41f7b16
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -40,6 +40,7 @@ Ref: https://keepachangelog.com/en/1.0.0/

### API Breaking

- (feemarket) [tharsis#1104](https://github.com/tharsis/ethermint/pull/1104) Enforce a minimum gas price for Cosmos and EVM transactions through the `MinGasPrice` parameter.
- (rpc) [tharsis#1081](https://github.com/tharsis/ethermint/pull/1081) Deduplicate some json-rpc logic codes, cleanup several dead functions.
- (ante) [tharsis#1062](https://github.com/tharsis/ethermint/pull/1062) Emit event of eth tx hash in ante handler to support query failed transactions.

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114 changes: 114 additions & 0 deletions app/ante/fees.go
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package ante

import (
sdk "github.com/cosmos/cosmos-sdk/types"
sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"

ethtypes "github.com/ethereum/go-ethereum/core/types"
evmtypes "github.com/tharsis/ethermint/x/evm/types"
)

// MinGasPriceDecorator will check if the transaction's fee is at least as large
// as the MinGasPrices param. If fee is too low, decorator returns error and tx
// is rejected. This applies for both CheckTx and DeliverTx
// If fee is high enough, then call next AnteHandler
// CONTRACT: Tx must implement FeeTx to use MinGasPriceDecorator
type MinGasPriceDecorator struct {
feesKeeper FeeMarketKeeper
evmKeeper EVMKeeper
}

func NewMinGasPriceDecorator(fk FeeMarketKeeper, ek EVMKeeper) MinGasPriceDecorator {
return MinGasPriceDecorator{feesKeeper: fk, evmKeeper: ek}
}

func (mpd MinGasPriceDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
minGasPrice := mpd.feesKeeper.GetParams(ctx).MinGasPrice
minGasPrices := sdk.DecCoins{sdk.DecCoin{
Denom: mpd.evmKeeper.GetParams(ctx).EvmDenom,
Amount: minGasPrice,
}}

feeTx, ok := tx.(sdk.FeeTx)
if !ok {
return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be a FeeTx")
}

feeCoins := feeTx.GetFee()
gas := feeTx.GetGas()

if !minGasPrices.IsZero() {
requiredFees := make(sdk.Coins, len(minGasPrices))

// Determine the required fees by multiplying each required minimum gas
// price by the gas limit, where fee = ceil(minGasPrice * gasLimit).
gasLimit := sdk.NewDec(int64(gas))
for i, gp := range minGasPrices {
fee := gp.Amount.Mul(gasLimit)
requiredFees[i] = sdk.NewCoin(gp.Denom, fee.Ceil().RoundInt())
}

if !feeCoins.IsAnyGTE(requiredFees) {
return ctx, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "provided fee < minimum global fee (%s < %s). Please increase the gas price.", feeCoins, requiredFees)
}
}

return next(ctx, tx, simulate)
}

// EthMinGasPriceDecorator will check if the transaction's fee is at least as large
// as the MinGasPrices param. If fee is too low, decorator returns error and tx
// is rejected. This applies to both CheckTx and DeliverTx and regardless
// if London hard fork or fee market params (EIP-1559) are enabled.
// If fee is high enough, then call next AnteHandler
type EthMinGasPriceDecorator struct {
feesKeeper FeeMarketKeeper
evmKeeper EVMKeeper
}

func NewEthMinGasPriceDecorator(fk FeeMarketKeeper, ek EVMKeeper) EthMinGasPriceDecorator {
return EthMinGasPriceDecorator{feesKeeper: fk, evmKeeper: ek}
}

func (empd EthMinGasPriceDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
minGasPrice := empd.feesKeeper.GetParams(ctx).MinGasPrice

if !minGasPrice.IsZero() {
for _, msg := range tx.GetMsgs() {
ethMsg, ok := msg.(*evmtypes.MsgEthereumTx)
if !ok {
return ctx, sdkerrors.Wrapf(sdkerrors.ErrUnknownRequest, "invalid message type %T, expected %T", msg, (*evmtypes.MsgEthereumTx)(nil))
}

feeAmt := ethMsg.GetFee()

// For dynamic transactions, GetFee() uses the GasFeeCap value, which
// is the maximum gas price that the signer can pay. In practice, the
// signer can pay less, if the block's BaseFee is lower. So, in this case,
// we use the EffectiveFee. If the feemarket formula results in a BaseFee
// that lowers EffectivePrice until it is < MinGasPrices, the users must
// increase the GasTipCap (priority fee) until EffectivePrice > MinGasPrices.
// Transactions with MinGasPrices * gasUsed < tx fees < EffectiveFee are rejected
// by the feemarket AnteHandle
txData, err := evmtypes.UnpackTxData(ethMsg.Data)
if err != nil {
return ctx, sdkerrors.Wrapf(err, "failed to unpack tx data %s", ethMsg.Hash)
}
if txData.TxType() != ethtypes.LegacyTxType {
paramsEvm := empd.evmKeeper.GetParams(ctx)
ethCfg := paramsEvm.ChainConfig.EthereumConfig(empd.evmKeeper.ChainID())
baseFee := empd.evmKeeper.GetBaseFee(ctx, ethCfg)
feeAmt = ethMsg.GetEffectiveFee(baseFee)
}

gasLimit := sdk.NewDec(int64(ethMsg.GetGas()))
requiredFee := minGasPrice.Mul(gasLimit)

if sdk.NewDecFromBigInt(feeAmt).LT(requiredFee) {
return ctx, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "provided fee < minimum global fee (%s < %s). Please increase the priority tip (for EIP-1559 txs) or the gas prices (for access list or legacy txs)", feeAmt, requiredFee)
}
}
}

return next(ctx, tx, simulate)
}
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