SMR-1782 ETH Child Bridge

.env.sample

@@ -10,5 +10,4 @@ ROOT_GAS_SERVICE_ADDRESS=
 CHILD_GAS_SERVICE_ADDRESS=
 ROOT_CHAIN_NAME=
 CHILD_CHAIN_NAME=
-ROOT_IMX_ADDRESS=
-CHILD_ETH_ADDRESS=
+ROOT_IMX_ADDRESS=

.gitignore

@@ -20,4 +20,6 @@ docs/
 .vscode/
 
 # Contract addresses
-addresses.json
+addresses.json
+
+/node_modules

script/DeployChildContracts.s.sol

@@ -14,7 +14,7 @@ contract DeployChildContracts is Script {
     function run() public {
         uint256 deployerPrivateKey = vm.envUint("CHILD_PRIVATE_KEY");
         address childGateway = vm.envAddress("CHILD_GATEWAY_ADDRESS");
-        address childGasService = vm.envAddress("CHILD_GAS_SERVICE_ADDRESS"); // Not yet used.
+        //address childGasService = vm.envAddress("CHILD_GAS_SERVICE_ADDRESS"); // Not yet used.
         string memory childRpcUrl = vm.envString("CHILD_RPC_URL");
 
         vm.createSelectFork(childRpcUrl);

script/InitializeRootContracts.s.sol

@@ -22,7 +22,6 @@ contract InitializeRootContracts is Script {
         string memory rootRpcUrl = vm.envString("ROOT_RPC_URL");
         uint256 rootPrivateKey = vm.envUint("ROOT_PRIVATE_KEY");
         address rootIMXToken = vm.envAddress("ROOT_IMX_ADDRESS");
-        address childETHToken = vm.envAddress("CHILD_ETH_ADDRESS");
 
         /**
          * INITIALIZE ROOT CHAIN CONTRACTS
@@ -31,12 +30,7 @@ contract InitializeRootContracts is Script {
         vm.startBroadcast(rootPrivateKey);
 
         rootERC20Bridge.initialize(
-            address(rootBridgeAdaptor),
-            childERC20Bridge,
-            childBridgeAdaptor,
-            rootChainChildTokenTemplate,
-            rootIMXToken,
-            childETHToken
+            address(rootBridgeAdaptor), childERC20Bridge, childBridgeAdaptor, rootChainChildTokenTemplate, rootIMXToken
         );
 
         rootBridgeAdaptor.setChildBridgeAdaptor();

src/child/ChildERC20Bridge.sol

@@ -33,36 +33,43 @@ contract ChildERC20Bridge is
 {
     using SafeERC20 for IERC20Metadata;
 
+    /// @dev leave this as the first param for the integration tests
+    mapping(address => address) public rootTokenToChildToken;
+
+    bytes32 public constant MAP_TOKEN_SIG = keccak256("MAP_TOKEN");
+    bytes32 public constant DEPOSIT_SIG = keccak256("DEPOSIT");
+    address public constant NATIVE_ETH = address(0xeee);
+
     IChildERC20BridgeAdaptor public bridgeAdaptor;
+
     /// @dev The address that will be sending messages to, and receiving messages from, the child chain.
     string public rootERC20BridgeAdaptor;
     /// @dev The address of the token template that will be cloned to create tokens.
     address public childTokenTemplate;
     /// @dev The name of the chain that this bridge is connected to.
     string public rootChain;
-    mapping(address => address) public rootTokenToChildToken;
-
-    bytes32 public constant MAP_TOKEN_SIG = keccak256("MAP_TOKEN");
-    bytes32 public constant DEPOSIT_SIG = keccak256("DEPOSIT");
-    address public imxToken;
+    /// @dev The address of the IMX ERC20 token on L1.
+    address public rootIMXToken;
+    /// @dev The address of the ETH ERC20 token on L2.
+    address public childETHToken;
 
     /**
      * @notice Initilization function for RootERC20Bridge.
      * @param newBridgeAdaptor Address of StateSender to send deposit information to.
      * @param newRootERC20BridgeAdaptor Stringified address of root ERC20 bridge adaptor to communicate with.
      * @param newChildTokenTemplate Address of child token template to clone.
      * @param newRootChain A stringified representation of the chain that this bridge is connected to. Used for validation.
-     * @param newIMXToken Address of ECR20 IMX on the root chain.
+     * @param newRootIMXToken Address of ECR20 IMX on the root chain.
      * @dev Can only be called once.
      */
     function initialize(
         address newBridgeAdaptor,
         string memory newRootERC20BridgeAdaptor,
         address newChildTokenTemplate,
         string memory newRootChain,
-        address newIMXToken
+        address newRootIMXToken
     ) public initializer {
-        if (newBridgeAdaptor == address(0) || newChildTokenTemplate == address(0) || newIMXToken == address(0)) {
+        if (newBridgeAdaptor == address(0) || newChildTokenTemplate == address(0) || newRootIMXToken == address(0)) {
             revert ZeroAddress();
         }
 
@@ -78,7 +85,12 @@ contract ChildERC20Bridge is
         childTokenTemplate = newChildTokenTemplate;
         bridgeAdaptor = IChildERC20BridgeAdaptor(newBridgeAdaptor);
         rootChain = newRootChain;
-        imxToken = newIMXToken;
+        rootIMXToken = newRootIMXToken;
+
+        IChildERC20 clonedETHToken =
+            IChildERC20(Clones.cloneDeterministic(childTokenTemplate, keccak256(abi.encodePacked(NATIVE_ETH))));
+        clonedETHToken.initialize(NATIVE_ETH, "Ethereum", "ETH", 18);
+        childETHToken = address(clonedETHToken);
     }
 
     /**
@@ -120,10 +132,14 @@ contract ChildERC20Bridge is
             revert ZeroAddress();
         }
 
-        if (address(rootToken) == imxToken) {
+        if (address(rootToken) == rootIMXToken) {
             revert CantMapIMX();
         }
 
+        if (address(rootToken) == NATIVE_ETH) {
+            revert CantMapETH();
+        }
+
         if (rootTokenToChildToken[rootToken] != address(0)) {
             revert AlreadyMapped();
         }
@@ -147,19 +163,29 @@ contract ChildERC20Bridge is
 
         address childToken;
 
-        if (address(rootToken) != imxToken) {
-            childToken = rootTokenToChildToken[address(rootToken)];
-            if (childToken == address(0)) {
-                revert NotMapped();
+        if (address(rootToken) != rootIMXToken) {
+            if (address(rootToken) == NATIVE_ETH) {
+                childToken = childETHToken;
+            } else {
+                childToken = rootTokenToChildToken[address(rootToken)];
+                if (childToken == address(0)) {
+                    revert NotMapped();
+                }
             }
+
             if (address(childToken).code.length == 0) {
                 revert EmptyTokenContract();
             }
 
             if (!IChildERC20(childToken).mint(receiver, amount)) {
                 revert MintFailed();
             }
-            emit ERC20Deposit(address(rootToken), childToken, sender, receiver, amount);
+
+            if (address(rootToken) == NATIVE_ETH) {
+                emit NativeEthDeposit(address(rootToken), childToken, sender, receiver, amount);
+            } else {
+                emit ERC20Deposit(address(rootToken), childToken, sender, receiver, amount);
+            }
         } else {
             Address.sendValue(payable(receiver), amount);
             emit IMXDeposit(address(rootToken), sender, receiver, amount);

src/interfaces/child/IChildERC20Bridge.sol

@@ -33,7 +33,7 @@ interface IChildERC20BridgeEvents {
         uint256 amount
     );
     event IMXDeposit(address indexed rootToken, address depositor, address indexed receiver, uint256 amount);
-    event NativeDeposit(
+    event NativeEthDeposit(
         address indexed rootToken,
         address indexed childToken,
         address depositor,
@@ -58,6 +58,8 @@ interface IChildERC20BridgeErrors {
     error NotMapped();
     /// @notice Error when attempting to map IMX.
     error CantMapIMX();
+    /// @notice Error when attempting to map ETH.
+    error CantMapETH();
     /// @notice Error when a token is already mapped.
     error AlreadyMapped();
     /// @notice Error when a message is given to the bridge from an address not the designated bridge adaptor.

src/interfaces/root/IRootERC20Bridge.sol

@@ -46,7 +46,7 @@ interface IRootERC20BridgeEvents {
         uint256 amount
     );
     event IMXDeposit(address indexed rootToken, address depositor, address indexed receiver, uint256 amount);
-    event NativeDeposit(
+    event NativeEthDeposit(
         address indexed rootToken,
         address indexed childToken,
         address depositor,
@@ -68,6 +68,8 @@ interface IRootERC20BridgeErrors {
     error NotMapped();
     /// @notice Error when attempting to map IMX.
     error CantMapIMX();
+    /// @notice Error when attempting to map ETH.
+    error CantMapETH();
     /// @notice Error when token balance invariant check fails.
     error BalanceInvariantCheckFailed(uint256 actualBalance, uint256 expectedBalance);
 }

src/root/RootERC20Bridge.sol

@@ -11,6 +11,7 @@ import {IAxelarGateway} from "@axelar-cgp-solidity/contracts/interfaces/IAxelarG
 import {IRootERC20Bridge, IERC20Metadata} from "../interfaces/root/IRootERC20Bridge.sol";
 import {IRootERC20BridgeEvents, IRootERC20BridgeErrors} from "../interfaces/root/IRootERC20Bridge.sol";
 import {IRootERC20BridgeAdaptor} from "../interfaces/root/IRootERC20BridgeAdaptor.sol";
+import {IChildERC20} from "../interfaces/child/IChildERC20.sol";
 
 /**
  * @notice RootERC20Bridge is a bridge that allows ERC20 tokens to be transferred from the root chain to the child chain.
@@ -29,19 +30,20 @@ contract RootERC20Bridge is
 {
     using SafeERC20 for IERC20Metadata;
 
+    /// @dev leave this as the first param for the integration tests
+    mapping(address => address) public rootTokenToChildToken;
+
     bytes32 public constant MAP_TOKEN_SIG = keccak256("MAP_TOKEN");
     bytes32 public constant DEPOSIT_SIG = keccak256("DEPOSIT");
-    address public constant NATIVE_TOKEN = address(0xeee);
+    address public constant NATIVE_ETH = address(0xeee);
 
     IRootERC20BridgeAdaptor public rootBridgeAdaptor;
     /// @dev Used to verify source address in messages sent from child chain.
-    /// @dev Stringified version of address.
     string public childBridgeAdaptor;
     /// @dev The address that will be minting tokens on the child chain.
     address public childERC20Bridge;
     /// @dev The address of the token template that will be cloned to create tokens on the child chain.
     address public childTokenTemplate;
-    mapping(address => address) public rootTokenToChildToken;
     /// @dev The address of the IMX ERC20 token on L1.
     address public rootIMXToken;
     /// @dev The address of the ETH ERC20 token on L2.
@@ -54,28 +56,29 @@ contract RootERC20Bridge is
      * @param newChildBridgeAdaptor Address of child bridge adaptor to communicate with.
      * @param newChildTokenTemplate Address of child token template to clone.
      * @param newRootIMXToken Address of ERC20 IMX on the root chain.
-     * @param newChildETHToken Address of ERC20 ETH on the child chain.
      * @dev Can only be called once.
      */
     function initialize(
         address newRootBridgeAdaptor,
         address newChildERC20Bridge,
         address newChildBridgeAdaptor,
         address newChildTokenTemplate,
-        address newRootIMXToken,
-        address newChildETHToken
+        address newRootIMXToken
     ) public initializer {
         if (
             newRootBridgeAdaptor == address(0) || newChildERC20Bridge == address(0)
                 || newChildTokenTemplate == address(0) || newChildBridgeAdaptor == address(0)
-                || newRootIMXToken == address(0) || newChildETHToken == address(0)
+                || newRootIMXToken == address(0)
         ) {
             revert ZeroAddress();
         }
         childERC20Bridge = newChildERC20Bridge;
         childTokenTemplate = newChildTokenTemplate;
         rootIMXToken = newRootIMXToken;
-        childETHToken = newChildETHToken;
+
+        childETHToken = Clones.predictDeterministicAddress(
+            childTokenTemplate, keccak256(abi.encodePacked(NATIVE_ETH)), childERC20Bridge
+        );
         rootBridgeAdaptor = IRootERC20BridgeAdaptor(newRootBridgeAdaptor);
         childBridgeAdaptor = Strings.toHexString(newChildBridgeAdaptor);
     }
@@ -108,7 +111,7 @@ contract RootERC20Bridge is
 
         uint256 expectedBalance = address(this).balance - (msg.value - amount);
 
-        _deposit(IERC20Metadata(NATIVE_TOKEN), receiver, amount);
+        _deposit(IERC20Metadata(NATIVE_ETH), receiver, amount);
 
         // invariant check to ensure that the root native balance has increased by the amount deposited
         if (address(this).balance != expectedBalance) {
@@ -147,6 +150,11 @@ contract RootERC20Bridge is
         if (address(rootToken) == rootIMXToken) {
             revert CantMapIMX();
         }
+
+        if (address(rootToken) == NATIVE_ETH) {
+            revert CantMapETH();
+        }
+
         if (rootTokenToChildToken[address(rootToken)] != address(0)) {
             revert AlreadyMapped();
         }
@@ -184,7 +192,7 @@ contract RootERC20Bridge is
         // TODO We can call _mapToken here, but ordering in the GMP is not guaranteed.
         //      Therefore, we need to decide how to handle this and it may be a UI decision to wait until map token message is executed on child chain.
         //      Discuss this, and add this decision to the design doc.
-        if (address(rootToken) != NATIVE_TOKEN) {
+        if (address(rootToken) != NATIVE_ETH) {
             if (address(rootToken) != rootIMXToken) {
                 childToken = rootTokenToChildToken[address(rootToken)];
                 if (childToken == address(0)) {
@@ -204,8 +212,8 @@ contract RootERC20Bridge is
 
         rootBridgeAdaptor.sendMessage{value: feeAmount}(payload, msg.sender);
 
-        if (address(rootToken) == NATIVE_TOKEN) {
-            emit NativeDeposit(address(rootToken), childETHToken, msg.sender, receiver, amount);
+        if (address(rootToken) == NATIVE_ETH) {
+            emit NativeEthDeposit(address(rootToken), childETHToken, msg.sender, receiver, amount);
         } else if (address(rootToken) == rootIMXToken) {
             emit IMXDeposit(address(rootToken), msg.sender, receiver, amount);
         } else {

test/integration/child/ChildAxelarBridge.t.sol

@@ -18,7 +18,8 @@ import {Utils} from "../../utils.t.sol";
 contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChildERC20BridgeErrors, Utils {
     string public ROOT_ADAPTOR_ADDRESS = Strings.toHexString(address(1));
     string public ROOT_CHAIN_NAME = "ROOT_CHAIN";
-    address constant IMX_TOKEN = address(9);
+    address constant IMX_TOKEN_ADDRESS = address(0xccc);
+    address constant NATIVE_ETH = address(0xeee);
 
     ChildERC20Bridge public childERC20Bridge;
     ChildERC20 public childERC20;
@@ -35,7 +36,11 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
             new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway), address(childERC20Bridge));
 
         childERC20Bridge.initialize(
-            address(childAxelarBridgeAdaptor), ROOT_ADAPTOR_ADDRESS, address(childERC20), ROOT_CHAIN_NAME, IMX_TOKEN
+            address(childAxelarBridgeAdaptor),
+            ROOT_ADAPTOR_ADDRESS,
+            address(childERC20),
+            ROOT_CHAIN_NAME,
+            IMX_TOKEN_ADDRESS
         );
     }
 
@@ -143,6 +148,47 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
         );
     }
 
+    function test_deposit_EmitsNativeDeposit() public {
+        address sender = address(0xff);
+        address receiver = address(0xee);
+        uint256 amount = 100;
+
+        address predictedChildETHToken = Clones.predictDeterministicAddress(
+            address(childERC20), keccak256(abi.encodePacked(NATIVE_ETH)), address(childERC20Bridge)
+        );
+
+        bytes32 commandId = bytes32("testCommandId");
+
+        vm.expectEmit(address(childERC20Bridge));
+        emit NativeEthDeposit(NATIVE_ETH, predictedChildETHToken, sender, receiver, amount);
+
+        childAxelarBridgeAdaptor.execute(
+            commandId,
+            ROOT_CHAIN_NAME,
+            ROOT_ADAPTOR_ADDRESS,
+            abi.encode(childERC20Bridge.DEPOSIT_SIG(), NATIVE_ETH, sender, receiver, amount)
+        );
+    }
+
+    function test_deposit_EmitsIMXDeposit() public {
+        address sender = address(0xff);
+        address receiver = address(0xee);
+        uint256 amount = 100;
+        bytes32 commandId = bytes32("testCommandId");
+
+        vm.deal(address(childERC20Bridge), 1 ether);
+
+        vm.expectEmit(address(childERC20Bridge));
+        emit IMXDeposit(IMX_TOKEN_ADDRESS, sender, receiver, amount);
+
+        childAxelarBridgeAdaptor.execute(
+            commandId,
+            ROOT_CHAIN_NAME,
+            ROOT_ADAPTOR_ADDRESS,
+            abi.encode(childERC20Bridge.DEPOSIT_SIG(), IMX_TOKEN_ADDRESS, sender, receiver, amount)
+        );
+    }
+
     function test_deposit_TransfersTokenToReceiver() public {
         address rootTokenAddress = address(456);
         address sender = address(0xff);
@@ -246,8 +292,8 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
         bytes32 depositSig = childERC20Bridge.DEPOSIT_SIG();
         address rootAddress = address(0x123);
         {
-            // Slot is 6 because of the Ownable, Initializable contracts coming first.
-            uint256 rootTokenToChildTokenMappingSlot = 6;
+            // Slot is 2 because of the Ownable, Initializable contracts coming first.
+            uint256 rootTokenToChildTokenMappingSlot = 2;
             address childAddress = address(444444);
             bytes32 slot = getMappingStorageSlotFor(rootAddress, rootTokenToChildTokenMappingSlot);
             bytes32 data = bytes32(uint256(uint160(childAddress)));