Smr 1813 withdraw erc20s

script/InitializeChildContracts.s.sol

@@ -20,6 +20,7 @@ contract InitializeChildContracts is Script {
         string memory childRpcUrl = vm.envString("CHILD_RPC_URL");
         string memory rootChainName = vm.envString("ROOT_CHAIN_NAME");
         address rootIMXToken = vm.envAddress("ROOT_IMX_ADDRESS");
+        address childGasService = vm.envAddress("CHILD_GAS_SERVICE_ADDRESS"); // Not yet used.
 
         /**
          * INITIALIZE CHILD CONTRACTS
@@ -35,7 +36,7 @@ contract InitializeChildContracts is Script {
             address(childAxelarBridgeAdaptor), rootBridgeAdaptorString, childTokenTemplate, rootChainName, rootIMXToken
         );
 
-        childAxelarBridgeAdaptor.initialize(address(childERC20Bridge));
+        childAxelarBridgeAdaptor.initialize(rootChainName, address(childERC20Bridge), childGasService);
 
         vm.stopBroadcast();
     }

src/child/ChildAxelarBridgeAdaptor.sol

@@ -2,26 +2,67 @@
 pragma solidity ^0.8.21;
 
 import {AxelarExecutable} from "@axelar-gmp-sdk-solidity/contracts/executable/AxelarExecutable.sol";
+import {IAxelarGasService} from "@axelar-cgp-solidity/contracts/interfaces/IAxelarGasService.sol";
+import {IAxelarGateway} from "@axelar-cgp-solidity/contracts/interfaces/IAxelarGateway.sol";
 import {Initializable} from "@openzeppelin/contracts/proxy/utils/Initializable.sol";
 import {IChildERC20Bridge} from "../interfaces/child/IChildERC20Bridge.sol";
-import {IChildAxelarBridgeAdaptorErrors} from "../interfaces/child/IChildAxelarBridgeAdaptor.sol";
+import {
+    IChildAxelarBridgeAdaptorErrors,
+    IChildAxelarBridgeAdaptorEvents
+} from "../interfaces/child/IChildAxelarBridgeAdaptor.sol";
+import {IChildERC20BridgeAdaptor} from "../interfaces/child/IChildERC20BridgeAdaptor.sol";
 
-contract ChildAxelarBridgeAdaptor is AxelarExecutable, Initializable, IChildAxelarBridgeAdaptorErrors {
+contract ChildAxelarBridgeAdaptor is
+    AxelarExecutable,
+    IChildERC20BridgeAdaptor,
+    Initializable,
+    IChildAxelarBridgeAdaptorErrors,
+    IChildAxelarBridgeAdaptorEvents
+{
     /// @notice Address of bridge to relay messages to.
     IChildERC20Bridge public childBridge;
+    IAxelarGasService public gasService;
+    string public rootBridgeAdaptor;
+    string public rootChain;
 
     constructor(address _gateway) AxelarExecutable(_gateway) {}
 
     /**
      * @notice Initializes the contract.
      * @param _childBridge Address of the child bridge contract.
      */
-    function initialize(address _childBridge) external initializer {
+    function initialize(string memory _rootChain, address _childBridge, address _gasService) external initializer {
         if (_childBridge == address(0)) {
             revert ZeroAddress();
         }
 
         childBridge = IChildERC20Bridge(_childBridge);
+        rootChain = _rootChain;
+        gasService = IAxelarGasService(_gasService);
+        rootBridgeAdaptor = childBridge.rootERC20BridgeAdaptor();
+    }
+
+    /**
+     * TODO
+     */
+    function sendMessage(bytes calldata payload, address refundRecipient) external payable override {
+        if (msg.value == 0) {
+            revert NoGas();
+        }
+        if (msg.sender != address(childBridge)) {
+            revert CallerNotBridge();
+        }
+
+        // Load from storage.
+        string memory _rootBridgeAdaptor = rootBridgeAdaptor;
+        string memory _rootChain = rootChain;
+
+        gasService.payNativeGasForContractCall{value: msg.value}(
+            address(this), _rootChain, _rootBridgeAdaptor, payload, refundRecipient
+        );
+
+        gateway.callContract(_rootChain, _rootBridgeAdaptor, payload);
+        emit AxelarMessage(_rootChain, _rootBridgeAdaptor, payload);
     }
 
     /**

src/child/ChildERC20Bridge.sol

@@ -38,6 +38,7 @@ contract ChildERC20Bridge is
 
     bytes32 public constant MAP_TOKEN_SIG = keccak256("MAP_TOKEN");
     bytes32 public constant DEPOSIT_SIG = keccak256("DEPOSIT");
+    bytes32 public constant WITHDRAW_SIG = keccak256("WITHDRAW");
     address public constant NATIVE_ETH = address(0xeee);
 
     IChildERC20BridgeAdaptor public bridgeAdaptor;
@@ -125,6 +126,50 @@ contract ChildERC20Bridge is
         }
     }
 
+    function withdraw(IChildERC20 childToken, uint256 amount) external payable {
+        _withdraw(childToken, msg.sender, amount);
+    }
+
+    function withdrawTo(IChildERC20 childToken, address receiver, uint256 amount) external payable {
+        _withdraw(childToken, receiver, amount);
+    }
+
+    function _withdraw(IChildERC20 childToken, address receiver, uint256 amount) private {
+        if (address(childToken).code.length == 0) {
+            revert EmptyTokenContract();
+        }
+
+        address rootToken = childToken.rootToken();
+
+        if (rootTokenToChildToken[rootToken] != address(childToken)) {
+            revert NotMapped();
+        }
+
+        // A mapped token should never have root token unset
+        if (rootToken == address(0)) {
+            revert ZeroAddressRootToken();
+        }
+
+        // A mapped token should never have the bridge unset
+        if (childToken.bridge() != address(this)) {
+            revert BridgeNotSet();
+        }
+
+        if (!childToken.burn(msg.sender, amount)) {
+            revert BurnFailed();
+        }
+
+        // TODO Should we enforce receiver != 0? old poly contracts don't
+
+        // Encode the message payload
+        bytes memory payload = abi.encode(WITHDRAW_SIG, rootToken, msg.sender, receiver, amount);
+
+        // Send the message to the bridge adaptor and up to root chain
+        bridgeAdaptor.sendMessage{value: msg.value}(payload, msg.sender);
+
+        emit ChildChainERC20Withdraw(rootToken, address(childToken), msg.sender, receiver, amount);
+    }
+
     function _mapToken(bytes calldata data) private {
         (, address rootToken, string memory name, string memory symbol, uint8 decimals) =
             abi.decode(data, (bytes32, address, string, string, uint8));
@@ -185,7 +230,7 @@ contract ChildERC20Bridge is
             if (address(rootToken) == NATIVE_ETH) {
                 emit NativeEthDeposit(address(rootToken), childToken, sender, receiver, amount);
             } else {
-                emit ERC20Deposit(address(rootToken), childToken, sender, receiver, amount);
+                emit ChildChainERC20Deposit(address(rootToken), childToken, sender, receiver, amount);
             }
         } else {
             Address.sendValue(payable(receiver), amount);

src/interfaces/child/IChildAxelarBridgeAdaptor.sol

@@ -4,4 +4,13 @@ pragma solidity ^0.8.21;
 interface IChildAxelarBridgeAdaptorErrors {
     /// @notice Error when a zero address is given when not valid.
     error ZeroAddress();
+    /// @notice Error when a message is sent with no gas payment.
+    error NoGas();
+    /// @notice Error when the caller is not the bridge.
+    error CallerNotBridge();
+}
+
+interface IChildAxelarBridgeAdaptorEvents {
+    /// @notice Emitted when an Axelar message is sent to the root chain.
+    event AxelarMessage(string indexed rootChain, string indexed rootBridgeAdaptor, bytes indexed payload);
 }

src/interfaces/child/IChildERC20Bridge.sol

@@ -25,7 +25,15 @@ interface IChildERC20BridgeEvents {
     /// @notice Emitted when a map token message is received from the root chain and executed successfully.
     event L2TokenMapped(address rootToken, address childToken);
 
-    event ERC20Deposit(
+    event ChildChainERC20Withdraw(
+        address indexed rootToken,
+        address indexed childToken,
+        address depositor,
+        address indexed receiver,
+        uint256 amount
+    );
+
+    event ChildChainERC20Deposit(
         address indexed rootToken,
         address indexed childToken,
         address depositor,
@@ -70,4 +78,10 @@ interface IChildERC20BridgeErrors {
     error InvalidSourceChain();
     /// @notice Error when the source chain's message sender is not a recognised address.
     error InvalidSourceAddress();
+    /// @notice Error when a given child token's root token is the zero address.
+    error ZeroAddressRootToken();
+    /// @notice Error when a given child token's bridge address is not set.
+    error BridgeNotSet();
+    /// @notice Error when a call to the given child token's `burn` function fails.
+    error BurnFailed();
 }

src/interfaces/child/IChildERC20BridgeAdaptor.sol

@@ -1,5 +1,12 @@
 // SPDX-License-Identifier: Apache 2.0
 pragma solidity ^0.8.21;
 
-// TODO to be used when sending messages L2 -> L1
-interface IChildERC20BridgeAdaptor {}
+interface IChildERC20BridgeAdaptor {
+    /**
+     * @notice Send an arbitrary message to the root chain via the message passing protocol.
+     * @param payload The message to send, encoded in a `bytes` array.
+     * @param refundRecipient Used if the message passing protocol requires fees & pays back excess to a refund recipient.
+     * @dev `payable` because the message passing protocol may require a fee to be paid.
+     */
+    function sendMessage(bytes calldata payload, address refundRecipient) external payable;
+}

src/interfaces/root/IRootAxelarBridgeAdaptor.sol

@@ -14,5 +14,5 @@ interface IRootAxelarBridgeAdaptorErrors {
 
 interface IRootAxelarBridgeAdaptorEvents {
     /// @notice Emitted when an Axelar message is sent to the child chain.
-    event MapTokenAxelarMessage(string indexed childChain, string indexed childBridgeAdaptor, bytes indexed payload);
+    event AxelarMessage(string indexed childChain, string indexed childBridgeAdaptor, bytes indexed payload);
 }

src/interfaces/root/IRootERC20Bridge.sol

@@ -38,7 +38,7 @@ interface IRootERC20BridgeEvents {
     /// @notice Emitted when a map token message is sent to the child chain.
     event L1TokenMapped(address indexed rootToken, address indexed childToken);
     /// @notice Emitted when an ERC20 deposit message is sent to the child chain.
-    event ERC20Deposit(
+    event ChildChainERC20Deposit(
         address indexed rootToken,
         address indexed childToken,
         address depositor,

src/root/RootAxelarBridgeAdaptor.sol

@@ -28,8 +28,7 @@ contract RootAxelarBridgeAdaptor is
     using SafeERC20 for IERC20Metadata;
 
     address public rootBridge;
-    /// @dev childChain could be immutable, but as of writing this Solidity does not support immutable strings.
-    ///      see: https://ethereum.stackexchange.com/questions/127622/typeerror-immutable-variables-cannot-have-a-non-value-type
+    string public childBridgeAdaptor;
     string public childChain;
     IAxelarGateway public axelarGateway;
     IAxelarGasService public gasService;
@@ -81,6 +80,6 @@ contract RootAxelarBridgeAdaptor is
         );
 
         axelarGateway.callContract(_childChain, _childBridgeAdaptor, payload);
-        emit MapTokenAxelarMessage(_childChain, _childBridgeAdaptor, payload);
+        emit AxelarMessage(_childChain, _childBridgeAdaptor, payload);
     }
 }

src/root/RootERC20Bridge.sol

@@ -267,7 +267,7 @@ contract RootERC20Bridge is
         } else if (address(rootToken) == rootIMXToken) {
             emit IMXDeposit(address(rootToken), msg.sender, receiver, amount);
         } else {
-            emit ERC20Deposit(address(rootToken), childToken, msg.sender, receiver, amount);
+            emit ChildChainERC20Deposit(address(rootToken), childToken, msg.sender, receiver, amount);
         }
     }
 }

src/test/child/ChildERC20FailOnBurn.sol

@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: Apache 2.0
+// Adapted from OpenZeppelin Contracts (last updated v4.8.0) (token/ERC20/ERC20.sol)
+pragma solidity ^0.8.21;
+
+import "../../child/ChildERC20.sol";
+
+/**
+ *   @title ChildERC20FailOnBurn
+ *   @author Immutable (@Benjimmutable)
+ *   @notice ChildERC20 contract, except burn always returns false. Used for testing.
+ *   @dev USED FOR TESTING
+ */
+// solhint-disable reason-string
+contract ChildERC20FailOnBurn is ChildERC20 {
+    function burn(address account, uint256 amount) public virtual override returns (bool) {
+        return false;
+    }
+}

src/test/child/MockChildAxelarGasService.sol

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: Apache 2.0
+pragma solidity ^0.8.21;
+
+contract MockChildAxelarGasService {
+    function payNativeGasForContractCall(
+        address sender,
+        string calldata destinationChain,
+        string calldata destinationAddress,
+        bytes calldata payload,
+        address refundAddress
+    ) external payable {}
+}

src/test/child/MockChildAxelarGateway.sol

@@ -5,4 +5,6 @@ contract MockChildAxelarGateway {
     function validateContractCall(bytes32, string calldata, string calldata, bytes32) external pure returns (bool) {
         return true;
     }
+
+    function callContract(string memory childChain, string memory childBridgeAdaptor, bytes memory payload) external {}
 }

test/integration/child/ChildAxelarBridge.t.sol

@@ -1,4 +1,4 @@
-// SPDX-License-Identifier: MIT
+// SPDX-License-Identifier: Apache 2.0
 pragma solidity ^0.8.21;
 
 import {Test, console2} from "forge-std/Test.sol";
@@ -13,6 +13,7 @@ import {
 } from "../../../src/child/ChildERC20Bridge.sol";
 import {IChildERC20, ChildERC20} from "../../../src/child/ChildERC20.sol";
 import {MockChildAxelarGateway} from "../../../src/test/child/MockChildAxelarGateway.sol";
+import {MockChildAxelarGasService} from "../../../src/test/child/MockChildAxelarGasService.sol";
 import {Utils} from "../../utils.t.sol";
 
 contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChildERC20BridgeErrors, Utils {
@@ -25,13 +26,15 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
     ChildERC20 public childERC20;
     ChildAxelarBridgeAdaptor public childAxelarBridgeAdaptor;
     MockChildAxelarGateway public mockChildAxelarGateway;
+    MockChildAxelarGasService public mockChildAxelarGasService;
 
     function setUp() public {
         childERC20 = new ChildERC20();
         childERC20.initialize(address(123), "Test", "TST", 18);
 
         childERC20Bridge = new ChildERC20Bridge();
         mockChildAxelarGateway = new MockChildAxelarGateway();
+        mockChildAxelarGasService = new MockChildAxelarGasService();
         childAxelarBridgeAdaptor = new ChildAxelarBridgeAdaptor(address(mockChildAxelarGateway));
 
         childERC20Bridge.initialize(
@@ -42,7 +45,9 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
             IMX_TOKEN_ADDRESS
         );
 
-        childAxelarBridgeAdaptor.initialize(address(childERC20Bridge));
+        childAxelarBridgeAdaptor.initialize(
+            ROOT_CHAIN_NAME, address(childERC20Bridge), address(mockChildAxelarGasService)
+        );
     }
 
     function test_ChildTokenMap() public {
@@ -130,7 +135,7 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
     /*
      * DEPOSIT
      */
-    function test_deposit_EmitsERC20Deposit() public {
+    function test_deposit_EmitsChildChainERC20Deposit() public {
         address rootTokenAddress = address(456);
         address sender = address(0xff);
         address receiver = address(0xee);
@@ -139,7 +144,7 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
         bytes32 commandId = bytes32("testCommandId");
 
         vm.expectEmit(address(childERC20Bridge));
-        emit ERC20Deposit(rootTokenAddress, childToken, sender, receiver, amount);
+        emit ChildChainERC20Deposit(rootTokenAddress, childToken, sender, receiver, amount);
 
         childAxelarBridgeAdaptor.execute(
             commandId,
@@ -294,6 +299,7 @@ contract ChildERC20BridgeIntegrationTest is Test, IChildERC20BridgeEvents, IChil
         address rootAddress = address(0x123);
         {
             // Slot is 2 because of the Ownable, Initializable contracts coming first.
+            // Found by running `forge inspect src/child/ChildERC20Bridge.sol:ChildERC20Bridge storageLayout | grep -B3 -A5 -i "rootTokenToChildToken"`
             uint256 rootTokenToChildTokenMappingSlot = 2;
             address childAddress = address(444444);
             bytes32 slot = getMappingStorageSlotFor(rootAddress, rootTokenToChildTokenMappingSlot);