feat: bypass min fee check for custom message types

CHANGELOG.md

@@ -36,7 +36,13 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+- [#1447](https://github.com/cosmos/gaia/pull/1447) Support custom message types to bypass minimum fee checks for.
+  If a transaction contains only bypassed message types, the transaction will not have minimum fee
+  checks performed during `CheckTx`. Operators can supply these message types via the `bypass-min-fee-msg-types`
+  configuration in `app.toml`. Note, by default they include various IBC message types.
+
 ## [v7.0.0] - 2022-03-24
+
 - (gaia) bump [cosmos-sdk](https://github.com/cosmos/cosmos-sdk) to [v0.45.1](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.45.1). See [CHANGELOG.md](https://github.com/cosmos/cosmos-sdk/blob/v0.45.1/CHANGELOG.md#v0451---2022-02-03) for details.
 - (gaia) bump [ibc-go](https://github.com/cosmos/ibc-go) module to [v3.0.0](https://github.com/cosmos/ibc-go/releases/tag/v3.0.0). See [CHANGELOG.md](https://github.com/cosmos/ibc-go/blob/v3.0.0/CHANGELOG.md#v300---2022-03-15) for details.
 - (gaia) add [interchain account](https://github.com/cosmos/ibc-go/tree/main/modules/apps/27-interchain-accounts) module (interhchain-account module is part of ibc-go module).
@@ -45,6 +51,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 - (gaia) add migration logs for upgrade process.
 
 ## [v6.0.4] - 2022-03-10
+
 * (gaia) Bump [Liquidity](https://github.com/gravity-devs/liquidity) module to [v1.4.6](https://github.com/Gravity-Devs/liquidity/releases/tag/v1.4.6).
 * (gaia) Bump [IBC](https://github.com/cosmos/ibc-go) module to [2.0.3](https://github.com/cosmos/ibc-go/releases/tag/v2.0.3).
 * (gaia) [#1230](https://github.com/cosmos/gaia/pull/1230) Fix: update gRPC Web Configuration in `contrib/testnets/test_platform`.

app/ante_handler.go → ante/ante.go

@@ -1,4 +1,4 @@
-package gaia
+package ante
 
 import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -12,41 +12,43 @@ import (
 // channel keeper.
 type HandlerOptions struct {
 	ante.HandlerOptions
-	IBCkeeper *ibckeeper.Keeper
+
+	IBCkeeper            *ibckeeper.Keeper
+	BypassMinFeeMsgTypes []string
 }
 
-func NewAnteHandler(options HandlerOptions) (sdk.AnteHandler, error) {
-	if options.AccountKeeper == nil {
+func NewAnteHandler(opts HandlerOptions) (sdk.AnteHandler, error) {
+	if opts.AccountKeeper == nil {
 		return nil, sdkerrors.Wrap(sdkerrors.ErrLogic, "account keeper is required for AnteHandler")
 	}
-	if options.BankKeeper == nil {
+	if opts.BankKeeper == nil {
 		return nil, sdkerrors.Wrap(sdkerrors.ErrLogic, "bank keeper is required for AnteHandler")
 	}
-	if options.SignModeHandler == nil {
+	if opts.SignModeHandler == nil {
 		return nil, sdkerrors.Wrap(sdkerrors.ErrLogic, "sign mode handler is required for ante builder")
 	}
 
-	var sigGasConsumer = options.SigGasConsumer
+	var sigGasConsumer = opts.SigGasConsumer
 	if sigGasConsumer == nil {
 		sigGasConsumer = ante.DefaultSigVerificationGasConsumer
 	}
 
 	anteDecorators := []sdk.AnteDecorator{
 		ante.NewSetUpContextDecorator(),
 		ante.NewRejectExtensionOptionsDecorator(),
-		ante.NewMempoolFeeDecorator(),
+		NewMempoolFeeDecorator(opts.BypassMinFeeMsgTypes),
 		ante.NewValidateBasicDecorator(),
 		ante.NewTxTimeoutHeightDecorator(),
-		ante.NewValidateMemoDecorator(options.AccountKeeper),
-		ante.NewConsumeGasForTxSizeDecorator(options.AccountKeeper),
-		ante.NewDeductFeeDecorator(options.AccountKeeper, options.BankKeeper, options.FeegrantKeeper),
+		ante.NewValidateMemoDecorator(opts.AccountKeeper),
+		ante.NewConsumeGasForTxSizeDecorator(opts.AccountKeeper),
+		ante.NewDeductFeeDecorator(opts.AccountKeeper, opts.BankKeeper, opts.FeegrantKeeper),
 		// SetPubKeyDecorator must be called before all signature verification decorators
-		ante.NewSetPubKeyDecorator(options.AccountKeeper),
-		ante.NewValidateSigCountDecorator(options.AccountKeeper),
-		ante.NewSigGasConsumeDecorator(options.AccountKeeper, sigGasConsumer),
-		ante.NewSigVerificationDecorator(options.AccountKeeper, options.SignModeHandler),
-		ante.NewIncrementSequenceDecorator(options.AccountKeeper),
-		ibcante.NewAnteDecorator(options.IBCkeeper),
+		ante.NewSetPubKeyDecorator(opts.AccountKeeper),
+		ante.NewValidateSigCountDecorator(opts.AccountKeeper),
+		ante.NewSigGasConsumeDecorator(opts.AccountKeeper, sigGasConsumer),
+		ante.NewSigVerificationDecorator(opts.AccountKeeper, opts.SignModeHandler),
+		ante.NewIncrementSequenceDecorator(opts.AccountKeeper),
+		ibcante.NewAnteDecorator(opts.IBCkeeper),
 	}
 
 	return sdk.ChainAnteDecorators(anteDecorators...), nil

ante/ante_test.go

@@ -0,0 +1,99 @@
+package ante_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/cosmos/cosmos-sdk/client"
+	"github.com/cosmos/cosmos-sdk/client/tx"
+	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
+	"github.com/cosmos/cosmos-sdk/simapp"
+	"github.com/cosmos/cosmos-sdk/testutil/testdata"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/cosmos/cosmos-sdk/types/tx/signing"
+	xauthsigning "github.com/cosmos/cosmos-sdk/x/auth/signing"
+	"github.com/stretchr/testify/suite"
+	tmrand "github.com/tendermint/tendermint/libs/rand"
+	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
+
+	gaiaapp "github.com/cosmos/gaia/v7/app"
+	gaiahelpers "github.com/cosmos/gaia/v7/app/helpers"
+)
+
+type IntegrationTestSuite struct {
+	suite.Suite
+
+	app         *gaiaapp.GaiaApp
+	anteHandler sdk.AnteHandler
+	ctx         sdk.Context
+	clientCtx   client.Context
+	txBuilder   client.TxBuilder
+}
+
+func TestIntegrationTestSuite(t *testing.T) {
+	suite.Run(t, new(IntegrationTestSuite))
+}
+
+func (s *IntegrationTestSuite) SetupTest() {
+	app := gaiahelpers.Setup(s.T(), false, 1)
+	ctx := app.BaseApp.NewContext(false, tmproto.Header{
+		ChainID: fmt.Sprintf("test-chain-%s", tmrand.Str(4)),
+		Height:  1,
+	})
+
+	encodingConfig := simapp.MakeTestEncodingConfig()
+	encodingConfig.Amino.RegisterConcrete(&testdata.TestMsg{}, "testdata.TestMsg", nil)
+	testdata.RegisterInterfaces(encodingConfig.InterfaceRegistry)
+
+	s.app = app
+	s.ctx = ctx
+	s.clientCtx = client.Context{}.WithTxConfig(encodingConfig.TxConfig)
+}
+
+func (s *IntegrationTestSuite) CreateTestTx(privs []cryptotypes.PrivKey, accNums []uint64, accSeqs []uint64, chainID string) (xauthsigning.Tx, error) {
+	var sigsV2 []signing.SignatureV2
+	for i, priv := range privs {
+		sigV2 := signing.SignatureV2{
+			PubKey: priv.PubKey(),
+			Data: &signing.SingleSignatureData{
+				SignMode:  s.clientCtx.TxConfig.SignModeHandler().DefaultMode(),
+				Signature: nil,
+			},
+			Sequence: accSeqs[i],
+		}
+
+		sigsV2 = append(sigsV2, sigV2)
+	}
+
+	if err := s.txBuilder.SetSignatures(sigsV2...); err != nil {
+		return nil, err
+	}
+
+	sigsV2 = []signing.SignatureV2{}
+	for i, priv := range privs {
+		signerData := xauthsigning.SignerData{
+			ChainID:       chainID,
+			AccountNumber: accNums[i],
+			Sequence:      accSeqs[i],
+		}
+		sigV2, err := tx.SignWithPrivKey(
+			s.clientCtx.TxConfig.SignModeHandler().DefaultMode(),
+			signerData,
+			s.txBuilder,
+			priv,
+			s.clientCtx.TxConfig,
+			accSeqs[i],
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		sigsV2 = append(sigsV2, sigV2)
+	}
+
+	if err := s.txBuilder.SetSignatures(sigsV2...); err != nil {
+		return nil, err
+	}
+
+	return s.txBuilder.GetTx(), nil
+}

ante/fee.go

@@ -0,0 +1,75 @@
+package ante
+
+import (
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
+	tmstrings "github.com/tendermint/tendermint/libs/strings"
+)
+
+const maxBypassMinFeeMsgGasUsage = uint64(200_000)
+
+// MempoolFeeDecorator will check if the transaction's fee is at least as large
+// as the local validator's minimum gasFee (defined in validator config).
+//
+// If fee is too low, decorator returns error and tx is rejected from mempool.
+// Note this only applies when ctx.CheckTx = true. If fee is high enough or not
+// CheckTx, then call next AnteHandler.
+//
+// CONTRACT: Tx must implement FeeTx to use MempoolFeeDecorator
+type MempoolFeeDecorator struct {
+	BypassMinFeeMsgTypes []string
+}
+
+func NewMempoolFeeDecorator(bypassMsgTypes []string) MempoolFeeDecorator {
+	return MempoolFeeDecorator{
+		BypassMinFeeMsgTypes: bypassMsgTypes,
+	}
+}
+
+func (mfd MempoolFeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, next sdk.AnteHandler) (newCtx sdk.Context, err error) {
+	feeTx, ok := tx.(sdk.FeeTx)
+	if !ok {
+		return ctx, sdkerrors.Wrap(sdkerrors.ErrTxDecode, "Tx must be a FeeTx")
+	}
+
+	feeCoins := feeTx.GetFee()
+	gas := feeTx.GetGas()
+	msgs := feeTx.GetMsgs()
+
+	// Only check for minimum fees if the execution mode is CheckTx and the tx does
+	// not contain operator configured bypass messages. If the tx does contain
+	// operator configured bypass messages only, it's total gas must be less than
+	// or equal to a constant, otherwise minimum fees are checked to prevent spam.
+	if ctx.IsCheckTx() && !simulate && !(mfd.bypassMinFeeMsgs(msgs) && gas <= uint64(len(msgs))*maxBypassMinFeeMsgGasUsage) {
+		minGasPrices := ctx.MinGasPrices()
+		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).
+			glDec := sdk.NewDec(int64(gas))
+			for i, gp := range minGasPrices {
+				fee := gp.Amount.Mul(glDec)
+				requiredFees[i] = sdk.NewCoin(gp.Denom, fee.Ceil().RoundInt())
+			}
+
+			if !feeCoins.IsAnyGTE(requiredFees) {
+				return ctx, sdkerrors.Wrapf(sdkerrors.ErrInsufficientFee, "insufficient fees; got: %s required: %s", feeCoins, requiredFees)
+			}
+		}
+	}
+
+	return next(ctx, tx, simulate)
+}
+
+func (mfd MempoolFeeDecorator) bypassMinFeeMsgs(msgs []sdk.Msg) bool {
+	for _, msg := range msgs {
+		if tmstrings.StringInSlice(sdk.MsgTypeURL(msg), mfd.BypassMinFeeMsgTypes) {
+			continue
+		}
+
+		return false
+	}
+
+	return true
+}

ante/fee_test.go

@@ -0,0 +1,59 @@
+package ante_test
+
+import (
+	cryptotypes "github.com/cosmos/cosmos-sdk/crypto/types"
+	"github.com/cosmos/cosmos-sdk/testutil/testdata"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	ibcclienttypes "github.com/cosmos/ibc-go/v3/modules/core/02-client/types"
+	ibcchanneltypes "github.com/cosmos/ibc-go/v3/modules/core/04-channel/types"
+
+	"github.com/cosmos/gaia/v7/ante"
+)
+
+func (s *IntegrationTestSuite) TestMempoolFeeDecorator() {
+	s.SetupTest()
+	s.txBuilder = s.clientCtx.TxConfig.NewTxBuilder()
+
+	mfd := ante.NewMempoolFeeDecorator([]string{
+		sdk.MsgTypeURL(&ibcchanneltypes.MsgRecvPacket{}),
+		sdk.MsgTypeURL(&ibcchanneltypes.MsgAcknowledgement{}),
+		sdk.MsgTypeURL(&ibcclienttypes.MsgUpdateClient{}),
+	})
+	antehandler := sdk.ChainAnteDecorators(mfd)
+	priv1, _, addr1 := testdata.KeyTestPubAddr()
+
+	msg := testdata.NewTestMsg(addr1)
+	feeAmount := testdata.NewTestFeeAmount()
+	gasLimit := testdata.NewTestGasLimit()
+	s.Require().NoError(s.txBuilder.SetMsgs(msg))
+	s.txBuilder.SetFeeAmount(feeAmount)
+	s.txBuilder.SetGasLimit(gasLimit)
+
+	privs, accNums, accSeqs := []cryptotypes.PrivKey{priv1}, []uint64{0}, []uint64{0}
+	tx, err := s.CreateTestTx(privs, accNums, accSeqs, s.ctx.ChainID())
+	s.Require().NoError(err)
+
+	// Set high gas price so standard test fee fails
+	feeAmt := sdk.NewDecCoinFromDec("uatom", sdk.NewDec(200).Quo(sdk.NewDec(100000)))
+	minGasPrice := []sdk.DecCoin{feeAmt}
+	s.ctx = s.ctx.WithMinGasPrices(minGasPrice).WithIsCheckTx(true)
+
+	// antehandler errors with insufficient fees
+	_, err = antehandler(s.ctx, tx, false)
+	s.Require().Error(err, "expected error due to low fee")
+
+	// ensure no fees for certain IBC msgs
+	s.Require().NoError(s.txBuilder.SetMsgs(
+		ibcchanneltypes.NewMsgRecvPacket(ibcchanneltypes.Packet{}, nil, ibcclienttypes.Height{}, ""),
+	))
+
+	oracleTx, err := s.CreateTestTx(privs, accNums, accSeqs, s.ctx.ChainID())
+	_, err = antehandler(s.ctx, oracleTx, false)
+	s.Require().NoError(err, "expected min fee bypass for IBC messages")
+
+	s.ctx = s.ctx.WithIsCheckTx(false)
+
+	// antehandler should not error since we do not check min gas prices in DeliverTx
+	_, err = antehandler(s.ctx, tx, false)
+	s.Require().NoError(err, "unexpected error during DeliverTx")
+}

app/app.go

@@ -104,11 +104,13 @@ import (
 	tmos "github.com/tendermint/tendermint/libs/os"
 	dbm "github.com/tendermint/tm-db"
 
-	gaiaappparams "github.com/cosmos/gaia/v7/app/params"
 	"github.com/strangelove-ventures/packet-forward-middleware/v2/router"
 	routerkeeper "github.com/strangelove-ventures/packet-forward-middleware/v2/router/keeper"
 	routertypes "github.com/strangelove-ventures/packet-forward-middleware/v2/router/types"
 
+	gaiaante "github.com/cosmos/gaia/v7/ante"
+	gaiaappparams "github.com/cosmos/gaia/v7/app/params"
+
 	// unnamed import of statik for swagger UI support
 	_ "github.com/cosmos/cosmos-sdk/client/docs/statik"
 )
@@ -602,16 +604,17 @@ func NewGaiaApp(
 	app.MountTransientStores(tkeys)
 	app.MountMemoryStores(memKeys)
 
-	anteHandler, err := NewAnteHandler(
-		HandlerOptions{
+	anteHandler, err := gaiaante.NewAnteHandler(
+		gaiaante.HandlerOptions{
 			HandlerOptions: ante.HandlerOptions{
 				AccountKeeper:   app.AccountKeeper,
 				BankKeeper:      app.BankKeeper,
 				FeegrantKeeper:  app.FeeGrantKeeper,
 				SignModeHandler: encodingConfig.TxConfig.SignModeHandler(),
 				SigGasConsumer:  ante.DefaultSigVerificationGasConsumer,
 			},
-			IBCkeeper: app.IBCKeeper,
+			IBCkeeper:            app.IBCKeeper,
+			BypassMinFeeMsgTypes: cast.ToStringSlice(appOpts.Get(gaiaappparams.BypassMinFeeMsgTypesKey)),
 		},
 	)
 	if err != nil {