Enforce simulation tax (#517)

custom/auth/ante/fee.go

@@ -51,7 +51,7 @@ func (fd FeeDecorator) AnteHandle(ctx sdk.Context, tx sdk.Tx, simulate bool, nex
 
 	msgs := feeTx.GetMsgs()
 	// Compute taxes
-	taxes := FilterMsgAndComputeTax(ctx, fd.treasuryKeeper, msgs...)
+	taxes := FilterMsgAndComputeTax(ctx, fd.treasuryKeeper, simulate, msgs...)
 
 	if !simulate {
 		priority, err = fd.checkTxFee(ctx, tx, taxes)
@@ -101,9 +101,24 @@ func (fd FeeDecorator) checkDeductFee(ctx sdk.Context, feeTx sdk.FeeTx, taxes sd
 
 	feesOrTax := fee
 
-	// deduct the fees
-	if fee.IsZero() && simulate {
-		feesOrTax = taxes
+	if simulate {
+		if fee.IsZero() {
+			feesOrTax = taxes
+		}
+
+		// even if fee is not zero it might be it is lower than the increased tax from computeTax
+		// so we need to check if the tax is higher than the fee to not run into deduction errors
+		for _, tax := range taxes {
+			feeAmount := feesOrTax.AmountOf(tax.Denom)
+			// if the fee amount is zero, add the tax amount to feesOrTax
+			if feeAmount.IsZero() {
+				feesOrTax = feesOrTax.Add(tax)
+			} else if feeAmount.LT(tax.Amount) {
+				// Update feesOrTax if the tax amount is higher
+				missingAmount := tax.Amount.Sub(feeAmount)
+				feesOrTax = feesOrTax.Add(sdk.NewCoin(tax.Denom, missingAmount))
+			}
+		}
 	}
 
 	if !feesOrTax.IsZero() {

custom/auth/ante/fee_tax.go

@@ -20,14 +20,14 @@ func isIBCDenom(denom string) bool {
 }
 
 // FilterMsgAndComputeTax computes the stability tax on messages.
-func FilterMsgAndComputeTax(ctx sdk.Context, tk TreasuryKeeper, msgs ...sdk.Msg) sdk.Coins {
+func FilterMsgAndComputeTax(ctx sdk.Context, tk TreasuryKeeper, simulate bool, msgs ...sdk.Msg) sdk.Coins {
 	taxes := sdk.Coins{}
 
 	for _, msg := range msgs {
 		switch msg := msg.(type) {
 		case *banktypes.MsgSend:
 			if !tk.HasBurnTaxExemptionAddress(ctx, msg.FromAddress, msg.ToAddress) {
-				taxes = taxes.Add(computeTax(ctx, tk, msg.Amount)...)
+				taxes = taxes.Add(computeTax(ctx, tk, msg.Amount, simulate)...)
 			}
 
 		case *banktypes.MsgMultiSend:
@@ -47,28 +47,28 @@ func FilterMsgAndComputeTax(ctx sdk.Context, tk TreasuryKeeper, msgs ...sdk.Msg)
 
 			if tainted != len(msg.Inputs)+len(msg.Outputs) {
 				for _, input := range msg.Inputs {
-					taxes = taxes.Add(computeTax(ctx, tk, input.Coins)...)
+					taxes = taxes.Add(computeTax(ctx, tk, input.Coins, simulate)...)
 				}
 			}
 
 		case *marketexported.MsgSwapSend:
-			taxes = taxes.Add(computeTax(ctx, tk, sdk.NewCoins(msg.OfferCoin))...)
+			taxes = taxes.Add(computeTax(ctx, tk, sdk.NewCoins(msg.OfferCoin), simulate)...)
 
 		case *wasmtypes.MsgInstantiateContract:
-			taxes = taxes.Add(computeTax(ctx, tk, msg.Funds)...)
+			taxes = taxes.Add(computeTax(ctx, tk, msg.Funds, simulate)...)
 
 		case *wasmtypes.MsgInstantiateContract2:
-			taxes = taxes.Add(computeTax(ctx, tk, msg.Funds)...)
+			taxes = taxes.Add(computeTax(ctx, tk, msg.Funds, simulate)...)
 
 		case *wasmtypes.MsgExecuteContract:
 			if !tk.HasBurnTaxExemptionContract(ctx, msg.Contract) {
-				taxes = taxes.Add(computeTax(ctx, tk, msg.Funds)...)
+				taxes = taxes.Add(computeTax(ctx, tk, msg.Funds, simulate)...)
 			}
 
 		case *authz.MsgExec:
 			messages, err := msg.GetMessages()
 			if err == nil {
-				taxes = taxes.Add(FilterMsgAndComputeTax(ctx, tk, messages...)...)
+				taxes = taxes.Add(FilterMsgAndComputeTax(ctx, tk, simulate, messages...)...)
 			}
 		}
 	}
@@ -77,7 +77,7 @@ func FilterMsgAndComputeTax(ctx sdk.Context, tk TreasuryKeeper, msgs ...sdk.Msg)
 }
 
 // computes the stability tax according to tax-rate and tax-cap
-func computeTax(ctx sdk.Context, tk TreasuryKeeper, principal sdk.Coins) sdk.Coins {
+func computeTax(ctx sdk.Context, tk TreasuryKeeper, principal sdk.Coins, simulate bool) sdk.Coins {
 	taxRate := tk.GetTaxRate(ctx)
 	if taxRate.Equal(sdk.ZeroDec()) {
 		return sdk.Coins{}
@@ -95,6 +95,12 @@ func computeTax(ctx sdk.Context, tk TreasuryKeeper, principal sdk.Coins) sdk.Coi
 		}
 
 		taxDue := sdk.NewDecFromInt(coin.Amount).Mul(taxRate).TruncateInt()
+		// we need to check all taxes if they are GTE 100 because otherwise we will not be able to
+		// simulate the split processes (i.e. BurnTaxSplit and OracleSplit)
+		// if they are less than 100, we will set them to 100
+		if simulate && taxDue.LT(sdk.NewInt(100)) {
+			taxDue = sdk.NewInt(100)
+		}
 
 		// If tax due is greater than the tax cap, cap!
 		taxCap := tk.GetTaxCap(ctx, coin.Denom)

custom/auth/ante/fee_test.go

@@ -832,7 +832,7 @@ func (s *AnteTestSuite) runBurnSplitTaxTest(burnSplitRate sdk.Dec, oracleSplitRa
 
 	feeCollectorAfter := bk.GetAllBalances(s.ctx, ak.GetModuleAddress(authtypes.FeeCollectorName))
 	oracleAfter := bk.GetAllBalances(s.ctx, ak.GetModuleAddress(oracletypes.ModuleName))
-	taxes := ante.FilterMsgAndComputeTax(s.ctx, tk, msg)
+	taxes := ante.FilterMsgAndComputeTax(s.ctx, tk, false, msg)
 	communityPoolAfter, _ := dk.GetFeePoolCommunityCoins(s.ctx).TruncateDecimal()
 	if communityPoolAfter.IsZero() {
 		communityPoolAfter = sdk.NewCoins(sdk.NewCoin(core.MicroSDRDenom, sdk.ZeroInt()))

custom/auth/tx/service.go

@@ -52,7 +52,7 @@ func (ts txServer) ComputeTax(c context.Context, req *ComputeTaxRequest) (*Compu
 		return nil, status.Errorf(codes.InvalidArgument, "empty txBytes is not allowed")
 	}
 
-	taxAmount := customante.FilterMsgAndComputeTax(ctx, ts.treasuryKeeper, msgs...)
+	taxAmount := customante.FilterMsgAndComputeTax(ctx, ts.treasuryKeeper, false, msgs...)
 	return &ComputeTaxResponse{
 		TaxAmount: taxAmount,
 	}, nil

custom/wasm/keeper/handler_plugin.go

@@ -78,7 +78,9 @@ func (h SDKMessageHandler) DispatchMsg(ctx sdk.Context, contractAddr sdk.AccAddr
 
 	for _, sdkMsg := range sdkMsgs {
 		// Charge tax on result msg
-		taxes := ante.FilterMsgAndComputeTax(ctx, h.treasuryKeeper, sdkMsg)
+		// we set simulate to false here as it is not available and we don't need to
+		// increase the tax amount for simulation inside of wasm
+		taxes := ante.FilterMsgAndComputeTax(ctx, h.treasuryKeeper, false, sdkMsg)
 		if !taxes.IsZero() {
 			eventManager := sdk.NewEventManager()
 			contractAcc := h.accountKeeper.GetAccount(ctx, contractAddr)