Restrict Asset Hub agent from executing contract calls in V2

contracts/src/Functions.sol

@@ -15,17 +15,16 @@ import {TokenInfo} from "./types/Common.sol";
 import {ChannelID, Channel} from "./v1/Types.sol";
 import {IGatewayBase} from "./interfaces/IGatewayBase.sol";
 import {IGatewayV1} from "./v1/IGateway.sol";
+import {Constants} from "./Constants.sol";
 
 // Common functionality that is shared between V1 and V2
 library Functions {
     using Address for address;
     using SafeNativeTransfer for address payable;
     using SafeTokenTransferFrom for IERC20;
 
-    error AgentDoesNotExist();
     error InvalidToken();
     error InvalidAmount();
-    error ChannelDoesNotExist();
 
     /// Looks up an agent contract address, failing if no such mapping exists
     function ensureAgent(bytes32 agentID) internal view returns (address agent) {
@@ -35,6 +34,14 @@ library Functions {
         }
     }
 
+    /// Looks up an agent contract address, failing if no such mapping exists or if the agent is the primary asset hub agent
+    function ensureNonPrivilegedAgent(bytes32 agentID) internal view returns (address agent) {
+        if(agentID == Constants.ASSET_HUB_AGENT_ID) {
+            revert IGatewayBase.UnauthorizedPrivilegedAgent();
+        }
+        agent = ensureAgent(agentID);
+    }
+
     /// @dev Ensure that the specified parachain has a channel allocated
     function ensureChannel(ChannelID channelID) internal view returns (Channel storage ch) {
         ch = CoreStorage.layout().channels[channelID];

contracts/src/interfaces/IGatewayBase.sol

@@ -13,6 +13,7 @@ interface IGatewayBase {
     error Unsupported();
     error InvalidDestinationFee();
     error AgentDoesNotExist();
+    error UnauthorizedPrivilegedAgent();
     error TokenAlreadyRegistered();
     error TokenMintFailed();
     error TokenTransferFailed();

contracts/src/v2/Handlers.sol

@@ -65,7 +65,7 @@ library HandlersV2 {
 
     function callContract(bytes32 origin, address executor, bytes calldata data) external {
         CallContractParams memory params = abi.decode(data, (CallContractParams));
-        address agent = Functions.ensureAgent(origin);
+        address agent = Functions.ensureNonPrivilegedAgent(origin);
         bytes memory call =
             abi.encodeCall(AgentExecutor.callContract, (params.target, params.data, params.value));
         Functions.invokeOnAgent(agent, executor, call);

contracts/test/GatewayV2.t.sol

@@ -579,6 +579,32 @@ contract GatewayV2Test is Test {
         vm.expectEmit(true, false, false, true);
         emit IGatewayV2.InboundMessageDispatched(1, topic, true, relayerRewardAddress);
 
+        address bridgeHubAgent = IGatewayV2(address(gateway)).agentOf(Constants.BRIDGE_HUB_AGENT_ID);
+        vm.deal(bridgeHubAgent, 1 ether);
+        hoax(relayer, 1 ether);
+        IGatewayV2(address(gateway))
+            .v2_submit(
+                InboundMessageV2({
+                    origin: Constants.BRIDGE_HUB_AGENT_ID,
+                    nonce: 1,
+                    topic: topic,
+                    commands: makeCallContractCommand(0.1 ether)
+                }),
+                proof,
+                makeMockProof(),
+                relayerRewardAddress
+            );
+    }
+
+    function testAgentCallContractFailsForAssetHub() public {
+        bytes32 topic = keccak256("topic");
+
+        // The command fails, then the message is dispatched with success: false
+        vm.expectEmit(true, false, false, false);
+        emit IGatewayV2.CommandFailed(1, 0);
+        vm.expectEmit(true, false, false, true);
+        emit IGatewayV2.InboundMessageDispatched(1, topic, false, relayerRewardAddress);
+
         vm.deal(assetHubAgent, 1 ether);
         hoax(relayer, 1 ether);
         IGatewayV2(address(gateway))