if feeRecipient is configured, verify it is not a known subaccount to avoid losing fees

- Spearbit #8

Author: hoytech

src/EulerSwapManagement.sol

@@ -21,6 +21,7 @@ contract EulerSwapManagement is EulerSwapBase {
     error BadDynamicParam();
     error AssetsOutOfOrderOrEqual();
     error InvalidAssets();
+    error BadFeeRecipient();
 
     /// @notice Emitted upon EulerSwap instance creation or reconfiguration.
     event EulerSwapConfigured(IEulerSwap.DynamicParams dParams, IEulerSwap.InitialState initialState);
@@ -87,6 +88,11 @@ contract EulerSwapManagement is EulerSwapBase {
 
         require(sParams.eulerAccount != sParams.feeRecipient, BadStaticParam()); // set feeRecipient to 0 instead
 
+        if (sParams.feeRecipient != address(0)) {
+            address owner = evc.getAccountOwner(sParams.feeRecipient);
+            require(owner == sParams.feeRecipient || owner == address(0), BadFeeRecipient());
+        }
+
         // Dynamic parameters
 
         if (initialState.reserve0 != 0) {

test/EulerSwapTestBase.t.sol

@@ -42,6 +42,7 @@ contract EulerSwapTestBase is EVaultTestBase {
     address installedOperator;
     bool expectInsufficientValidityBondRevert = false;
     bool expectAccountLiquidityRevert = false;
+    bool expectBadFeeRecipient = false;
 
     error E_AccountLiquidity();
 
@@ -172,13 +173,14 @@ contract EulerSwapTestBase is EVaultTestBase {
 
         vm.prank(holder);
         if (expectAccountLiquidityRevert) vm.expectRevert(E_AccountLiquidity.selector);
+        if (expectBadFeeRecipient) vm.expectRevert(EulerSwapManagement.BadFeeRecipient.selector);
         bytes memory result = IEVC(evc).call(
             address(eulerSwapFactory),
             sParams.eulerAccount,
             0,
             abi.encodeCall(EulerSwapFactory.deployPool, (sParams, dParams, initialState, salt))
         );
-        if (expectAccountLiquidityRevert) return EulerSwap(address(0)); // Just to return to test
+        if (expectAccountLiquidityRevert || expectBadFeeRecipient) return EulerSwap(address(0)); // Just to return to test
         EulerSwap eulerSwap = EulerSwap(abi.decode(result, (address)));
 
         vm.prank(holder);

test/Fees.t.sol

@@ -163,6 +163,23 @@ contract FeesTest is EulerSwapTestBase {
         assertEq(assetTST.balanceOf(address(54321)), amountIn - amountInNoFees);
     }
 
+    function test_altFeeRecipient_subAccount() public {
+        address recipient = makeAddr("feeRecipient");
+
+        // Register owner with EVC
+        vm.prank(recipient);
+        evc.enableCollateral(recipient, address(0));
+
+        address subAccount = address(uint160(recipient) ^ 1);
+
+        (IEulerSwap.StaticParams memory sParams, IEulerSwap.DynamicParams memory dParams) =
+            getEulerSwapParams(60e18, 60e18, 1e18, 1e18, 0.9e18, 0.9e18, 0.01e18, subAccount);
+        IEulerSwap.InitialState memory initialState = IEulerSwap.InitialState({reserve0: 60e18, reserve1: 60e18});
+
+        expectBadFeeRecipient = true;
+        eulerSwap = createEulerSwapFull(sParams, dParams, initialState);
+    }
+
     function test_fees_protocolFees_swap() public {
         uint256 fee = 0.05e18;
         uint256 protocolFee = 0.1e18;