feat: Update ForeignController to use modifiers (SC-1281) (#201)

* save

* add: modifiers

Author: supercontracts

src/ForeignController.sol

@@ -161,10 +161,8 @@ contract ForeignController is ReentrancyGuard, AccessControlEnumerable {
     }
 
     function setMaxExchangeRate(address token, uint256 shares, uint256 maxExpectedAssets)
-        external nonReentrant
+        external nonReentrant onlyRole(DEFAULT_ADMIN_ROLE)
     {
-        _checkRole(DEFAULT_ADMIN_ROLE);
-
         require(token != address(0), "FC/token-zero-address");
 
         emit MaxExchangeRateSet(
@@ -187,13 +185,14 @@ contract ForeignController is ReentrancyGuard, AccessControlEnumerable {
     /**********************************************************************************************/
 
     function transferAsset(address asset, address destination, uint256 amount)
-        external nonReentrant onlyRole(RELAYER)
-    {
-        _rateLimited(
+        external
+        nonReentrant
+        onlyRole(RELAYER)
+        rateLimited(
             RateLimitHelpers.makeAddressAddressKey(LIMIT_ASSET_TRANSFER, asset, destination),
             amount
-        );
-
+        )
+    {
         bytes memory returnData = proxy.doCall(
             asset,
             abi.encodeCall(IERC20(asset).transfer, (destination, amount))
@@ -298,19 +297,19 @@ contract ForeignController is ReentrancyGuard, AccessControlEnumerable {
         uint256 amount,
         uint32  destinationEndpointId
     )
-        external payable nonReentrant
+        external
+        payable
+        nonReentrant
+        onlyRole(RELAYER)
+        rateLimited(
+            keccak256(abi.encode(LIMIT_LAYERZERO_TRANSFER, oftAddress, destinationEndpointId)),
+            amount
+        )
     {
-        _checkRole(RELAYER);
-
         bytes32 recipient = layerZeroRecipients[destinationEndpointId];
 
         require(recipient != bytes32(0), "FC/recipient-not-set");
 
-        _rateLimited(
-            keccak256(abi.encode(LIMIT_LAYERZERO_TRANSFER, oftAddress, destinationEndpointId)),
-            amount
-        );
-
         // NOTE: Full integration testing of this logic is not possible without OFTs with
         //       approvalRequired == true. Add integration testing for this case before
         //       using in production.
@@ -602,10 +601,6 @@ contract ForeignController is ReentrancyGuard, AccessControlEnumerable {
         emit CCTPTransferInitiated(nonce, destinationDomain, mintRecipient, usdcAmount);
     }
 
-    function _rateLimited(bytes32 key, uint256 amount) internal {
-        rateLimits.triggerRateLimitDecrease(key, amount);
-    }
-
     /**********************************************************************************************/
     /*** Exchange rate helper functions                                                         ***/
     /**********************************************************************************************/