feat: configurable fee collector for DeductFeeDecorator (#407)

* feat: configurable fee collector for DeductFeeDecorator

* docs: update changelog with PR number

* test: ensure increment of alt account, comments

CHANGELOG-Agoric.md

@@ -37,7 +37,11 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## Unreleased
 
-### API Breaking Changes
+### Improvements
+
+* (auth) [#407](https://github.com/agoric-labs/cosmos-sdk/pull/407) Configurable fee collector module account in DeductFeeDecorator.
+
+### API Breaking
 
 * (auth, bank) Agoric/agoric-sdk#8989 Remove deprecated lien support
 

x/auth/ante/fee.go

@@ -23,24 +23,30 @@ type TxFeeChecker func(ctx context.Context, tx transaction.Tx) (sdk.Coins, int64
 // Call next AnteHandler if fees are successfully deducted.
 // CONTRACT: The Tx must implement the FeeTx interface to use DeductFeeDecorator.
 type DeductFeeDecorator struct {
-	accountKeeper  AccountKeeper
-	bankKeeper     types.BankKeeper
-	feegrantKeeper FeegrantKeeper
-	txFeeChecker   TxFeeChecker
-	minGasPrices   sdk.DecCoins
+	accountKeeper    AccountKeeper
+	bankKeeper       types.BankKeeper
+	feegrantKeeper   FeegrantKeeper
+	txFeeChecker     TxFeeChecker
+	feeCollectorName string
 }
 
-func NewDeductFeeDecorator(ak AccountKeeper, bk types.BankKeeper, fk FeegrantKeeper, tfc TxFeeChecker) *DeductFeeDecorator {
-	dfd := &DeductFeeDecorator{
-		accountKeeper:  ak,
-		bankKeeper:     bk,
-		feegrantKeeper: fk,
-		txFeeChecker:   tfc,
-		minGasPrices:   sdk.NewDecCoins(),
-	}
+func NewDeductFeeDecorator(ak AccountKeeper, bk types.BankKeeper, fk FeegrantKeeper, tfc TxFeeChecker) DeductFeeDecorator {
+	return NewDeductFeeDecoratorWithName(ak, bk, fk, tfc, types.FeeCollectorName)
+}
 
+// NewDeductFeeDecoratorWithName returns a DeductFeeDecorator using a custom fee collector module account.
+// Agoric note: for collecting fees in the reserve account.
+func NewDeductFeeDecoratorWithName(ak AccountKeeper, bk types.BankKeeper, fk FeegrantKeeper, tfc TxFeeChecker, feeCollectorName string) DeductFeeDecorator {
 	if tfc == nil {
-		dfd.txFeeChecker = dfd.checkTxFeeWithValidatorMinGasPrices
+		tfc = checkTxFeeWithValidatorMinGasPrices
+	}
+
+	return DeductFeeDecorator{
+		accountKeeper:    ak,
+		bankKeeper:       bk,
+		feegrantKeeper:   fk,
+		txFeeChecker:     tfc,
+		feeCollectorName: feeCollectorName,
 	}
 
 	return dfd
@@ -91,8 +97,8 @@ func (dfd *DeductFeeDecorator) innerValidateTx(ctx context.Context, tx transacti
 		}
 	}
 
-	if addr := dfd.accountKeeper.GetModuleAddress(types.FeeCollectorName); addr == nil {
-		return fmt.Errorf("fee collector module account (%s) has not been set", types.FeeCollectorName)
+	if addr := dfd.accountKeeper.GetModuleAddress(dfd.feeCollectorName); addr == nil {
+		return fmt.Errorf("fee collector module account (%s) has not been set", dfd.feeCollectorName)
 	}
 
 	feePayer := feeTx.FeePayer()
@@ -123,7 +129,8 @@ func (dfd *DeductFeeDecorator) innerValidateTx(ctx context.Context, tx transacti
 
 	// deduct the fees
 	if !fee.IsZero() {
-		if err := DeductFees(dfd.bankKeeper, ctx, deductFeesFrom, fee); err != nil {
+		err := DeductFees(dfd.bankKeeper, ctx, deductFeesFromAcc, fee, dfd.feeCollectorName)
+		if err != nil {
 			return err
 		}
 	}
@@ -141,13 +148,14 @@ func (dfd *DeductFeeDecorator) innerValidateTx(ctx context.Context, tx transacti
 }
 
 // DeductFees deducts fees from the given account.
-func DeductFees(bankKeeper types.BankKeeper, ctx context.Context, acc []byte, fees sdk.Coins) error {
+func DeductFees(bankKeeper types.BankKeeper, ctx sdk.Context, acc types.AccountI, fees sdk.Coins, feeCollectorName string) error {
 	if !fees.IsValid() {
 		return errorsmod.Wrapf(sdkerrors.ErrInsufficientFee, "invalid fee amount: %s", fees)
 	}
 
-	if err := bankKeeper.SendCoinsFromAccountToModule(ctx, acc, types.FeeCollectorName, fees); err != nil {
-		return fmt.Errorf("failed to deduct fees: %w", err)
+	err := bankKeeper.SendCoinsFromAccountToModule(ctx, acc.GetAddress(), feeCollectorName, fees)
+	if err != nil {
+		return sdkerrors.Wrapf(sdkerrors.ErrInsufficientFunds, err.Error())
 	}
 
 	return nil

x/auth/ante/fee_test.go

@@ -14,7 +14,8 @@ import (
 	sdkerrors "github.com/cosmos/cosmos-sdk/types/errors"
 	"github.com/cosmos/cosmos-sdk/types/tx/signing"
 	"github.com/cosmos/cosmos-sdk/x/auth/ante"
-	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
+	"github.com/cosmos/cosmos-sdk/x/auth/types"
+	"github.com/cosmos/cosmos-sdk/x/bank/testutil"
 )
 
 func (s *AnteTestSuite) TestDeductFeeDecorator_ZeroGas() {
@@ -155,3 +156,48 @@ func (s *AnteTestSuite) TestDeductFees() {
 
 	s.Require().Nil(err, "Tx errored after account has been set with sufficient funds")
 }
+
+func (s *AnteTestSuite) TestDeductFees_WithName() {
+	s.SetupTest(false) // setup
+	s.txBuilder = s.clientCtx.TxConfig.NewTxBuilder()
+
+	// keys and addresses
+	priv1, _, addr1 := testdata.KeyTestPubAddr()
+
+	// msg and signatures
+	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 transacting account with sufficient funds
+	acc := s.app.AccountKeeper.NewAccountWithAddress(s.ctx, addr1)
+	s.app.AccountKeeper.SetAccount(s.ctx, acc)
+	coins := sdk.NewCoins(sdk.NewCoin("atom", sdk.NewInt(200)))
+	err = testutil.FundAccount(s.app.BankKeeper, s.ctx, addr1, coins)
+	s.Require().NoError(err)
+
+	feeCollectorAcc := s.app.AccountKeeper.GetModuleAccount(s.ctx, types.FeeCollectorName)
+	// pick a simapp module account
+	altCollectorName := "distribution"
+	altCollectorAcc := s.app.AccountKeeper.GetModuleAccount(s.ctx, altCollectorName)
+	s.Require().True(s.app.BankKeeper.GetAllBalances(s.ctx, feeCollectorAcc.GetAddress()).Empty())
+	altBalance := s.app.BankKeeper.GetAllBalances(s.ctx, altCollectorAcc.GetAddress())
+
+	// Run the transaction through a handler chain that deducts fees into altCollectorAcc.
+	dfd := ante.NewDeductFeeDecoratorWithName(s.app.AccountKeeper, s.app.BankKeeper, nil, nil, altCollectorName)
+	antehandler := sdk.ChainAnteDecorators(dfd)
+	_, err = antehandler(s.ctx, tx, false)
+	s.Require().NoError(err)
+
+	s.Require().True(s.app.BankKeeper.GetAllBalances(s.ctx, feeCollectorAcc.GetAddress()).Empty())
+	newAltBalance := s.app.BankKeeper.GetAllBalances(s.ctx, altCollectorAcc.GetAddress())
+	s.Require().True(newAltBalance.IsAllGTE(altBalance))
+	s.Require().False(newAltBalance.IsEqual(altBalance))
+}