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ernestognwAmxxErnesto Garcíafrangio
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Cross-chain standardisation: ERC-7786 interfaces, helpers and Axelar adapter (#28)
* cross-chain prototype v1 * split common <> axelar * add relay observability * Update oz to master * Iterate * Remove salt * Iterate * Add GatewayAxelar specialization * Iterate * Fix GatewayAxelarSource * Remove unnecessary contract * Iteration * Remove interfaces * Checkpoint * Add incoming dual mode * Fix compilation * Apply review suggestions * Install axelar contracts * Apply review sugggestion * Apply suggestions * wip fixes * trying to get crosschain to compile * fix compilation * minor update * make attributes a bytes[] * Address comments and add some tests * refactor and test caip utils * up * using unmerged version of Strings with parsing * up * workflow testing (active and passive) * update * up * address PR comments * renovate * rename * fix foundry * codespell * use checksumed addresses * use @openzepplin/contracts@master * add/move files that are no longer planned to be in the main repo * get submodules when running tests * Apply suggestions from code review * Apply suggestions from code review Co-authored-by: Francisco Giordano <[email protected]> * simplify * update * validateReceivedMessage -> setExecutedMessage * Add docs * Update AxelarGatewayDestination.sol Co-authored-by: Francisco Giordano <[email protected]> * Update * Update * Pick CI changes * Run `forge update` * Sync prettier version with vanilla contracts * Point .gitmodules to master * fix imports * Implement audit recommendations for crosschain gateway implementations (#22) * Updated ERC specs * executeMessage returns bytes4 * Add AxelarGatewayDuplex * remove npm contracts dependency in favor of the master submodule * slither remappings * clarify CAIP-10 format * document reverts * unused imports * unexpected attributes too short * document remoteGateway format * clarify AxelarGatewayDestination._execute * rewrite require(..., error); as if (...) revert error; * typography * custom errors * replace require with string with custom error * Apply audit review suggestions * Adjust checks.yml * Point gitmodules to master on OZ contracts * lint * Fix CI * Fix CI 2 * Fix slither * up * up * Disable locked-ether slither rule for duplex * Make prettier version consistent * Remove passive mode * Apply suggestions from code review Co-authored-by: Ernesto García <[email protected]> * Update contracts/crosschain/axelar/AxelarGatewayDuplex.sol --------- Co-authored-by: Ernesto García <[email protected]> * cleanup --------- Co-authored-by: Hadrien Croubois <[email protected]> Co-authored-by: Ernesto García <[email protected]> Co-authored-by: Francisco Giordano <[email protected]>
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‎.github/workflows/checks.yml‎

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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v4
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with:
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submodules: recursive
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- name: Set up environment
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uses: ./.github/actions/setup
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- name: Run tests

‎.gitmodules‎

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[submodule "lib/@openzeppelin-contracts"]
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path = lib/@openzeppelin-contracts
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url = https://github.com/OpenZeppelin/openzeppelin-contracts.git
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branch = master
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[submodule "lib/@openzeppelin-contracts-upgradeable"]
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path = lib/@openzeppelin-contracts-upgradeable
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url = https://github.com/OpenZeppelin/openzeppelin-contracts-upgradeable.git
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branch = master
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[submodule "lib/forge-std"]
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path = lib/forge-std
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url = https://github.com/foundry-rs/forge-std.git

‎contracts/crosschain/axelar/AxelarGatewayBase.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.27;
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import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
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import {IAxelarGateway} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/interfaces/IAxelarGateway.sol";
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/**
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* @dev Base implementation of a cross-chain gateway adapter for the Axelar Network.
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*
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* This contract allows developers to register equivalence between chains (i.e. CAIP-2 chain identifiers
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* to Axelar chain identifiers) and remote gateways (i.e. gateways on other chains) to
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* facilitate cross-chain communication.
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*/
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abstract contract AxelarGatewayBase is Ownable {
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/// @dev A remote gateway has been registered for a chain.
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event RegisteredRemoteGateway(string caip2, string gatewayAddress);
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/// @dev A chain equivalence has been registered.
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event RegisteredChainEquivalence(string caip2, string destinationChain);
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/// @dev Error emitted when an unsupported chain is queried.
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error UnsupportedChain(string caip2);
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error ChainEquivalenceAlreadyRegistered(string caip2);
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error RemoteGatewayAlreadyRegistered(string caip2);
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/// @dev Axelar's official gateway for the current chain.
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IAxelarGateway public immutable localGateway;
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mapping(string caip2 => string remoteGateway) private _remoteGateways;
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mapping(string caip2OrAxelar => string axelarOrCaip2) private _chainEquivalence;
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/// @dev Sets the local gateway address (i.e. Axelar's official gateway for the current chain).
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constructor(IAxelarGateway _gateway) {
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localGateway = _gateway;
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}
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/// @dev Returns the equivalent chain given an id that can be either CAIP-2 or an Axelar network identifier.
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function getEquivalentChain(string memory input) public view virtual returns (string memory output) {
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output = _chainEquivalence[input];
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require(bytes(output).length > 0, UnsupportedChain(input));
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}
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/// @dev Returns the address string of the remote gateway for a given CAIP-2 chain identifier.
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function getRemoteGateway(string memory caip2) public view virtual returns (string memory remoteGateway) {
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remoteGateway = _remoteGateways[caip2];
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require(bytes(remoteGateway).length > 0, UnsupportedChain(caip2));
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}
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/// @dev Registers a chain equivalence between a CAIP-2 chain identifier and an Axelar network identifier.
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function registerChainEquivalence(string calldata caip2, string calldata axelarSupported) public virtual onlyOwner {
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require(bytes(_chainEquivalence[caip2]).length == 0, ChainEquivalenceAlreadyRegistered(caip2));
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_chainEquivalence[caip2] = axelarSupported;
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_chainEquivalence[axelarSupported] = caip2;
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emit RegisteredChainEquivalence(caip2, axelarSupported);
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}
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/// @dev Registers the address string of the remote gateway for a given CAIP-2 chain identifier.
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function registerRemoteGateway(string calldata caip2, string calldata remoteGateway) public virtual onlyOwner {
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require(bytes(_remoteGateways[caip2]).length == 0, RemoteGatewayAlreadyRegistered(caip2));
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_remoteGateways[caip2] = remoteGateway;
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emit RegisteredRemoteGateway(caip2, remoteGateway);
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}
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}

‎contracts/crosschain/axelar/AxelarGatewayDestination.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.27;
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import {AxelarExecutable} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/executable/AxelarExecutable.sol";
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import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
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import {IERC7786Receiver} from "../interfaces/draft-IERC7786.sol";
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import {AxelarGatewayBase} from "./AxelarGatewayBase.sol";
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/**
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* @dev Implementation of an ERC-7786 gateway destination adapter for the Axelar Network in dual mode.
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*
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* The contract implements AxelarExecutable's {_execute} function to execute the message, converting Axelar's native
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* workflow into the standard ERC-7786.
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*/
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abstract contract AxelarGatewayDestination is AxelarGatewayBase, AxelarExecutable {
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using Strings for address;
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using Strings for string;
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error InvalidOriginGateway(string sourceChain, string axelarSourceAddress);
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error ReceiverExecutionFailed();
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/**
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* @dev Active mode execution of a cross-chain message.
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*
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* In this function:
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*
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* - `axelarSourceChain` is in the Axelar format. It should not be expected to be a proper CAIP-2 format
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* - `axelarSourceAddress` is the sender of the Axelar message. That should be the remote gateway on the chain
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* which the message originates from. It is NOT the sender of the ERC-7786 crosschain message.
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*
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* Proper CAIP-10 encoding of the message sender (including the CAIP-2 name of the origin chain can be found in
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* the message)
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*/
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function _execute(
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string calldata axelarSourceChain, // chain of the remote gateway - axelar format
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string calldata axelarSourceAddress, // address of the remote gateway
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bytes calldata adapterPayload
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) internal override {
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// Parse the package
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(string memory sender, string memory receiver, bytes memory payload, bytes[] memory attributes) = abi.decode(
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adapterPayload,
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(string, string, bytes, bytes[])
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);
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// Axelar to CAIP-2 translation
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string memory sourceChain = getEquivalentChain(axelarSourceChain);
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// check message validity
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// - `axelarSourceAddress` is the remote gateway on the origin chain.
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require(
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getRemoteGateway(sourceChain).equal(axelarSourceAddress),
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InvalidOriginGateway(sourceChain, axelarSourceAddress)
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);
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// Active mode
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bytes4 result = IERC7786Receiver(receiver.parseAddress()).executeMessage(
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sourceChain,
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sender,
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payload,
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attributes
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);
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require(result == IERC7786Receiver.executeMessage.selector, ReceiverExecutionFailed());
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}
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}

‎contracts/crosschain/axelar/AxelarGatewayDuplex.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.27;
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import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
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import {AxelarGatewayBase, IAxelarGateway} from "./AxelarGatewayBase.sol";
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import {AxelarGatewayDestination, AxelarExecutable} from "./AxelarGatewayDestination.sol";
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import {AxelarGatewaySource} from "./AxelarGatewaySource.sol";
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/**
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* @dev A contract that combines the functionality of both the source and destination gateway
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* adapters for the Axelar Network. Allowing to either send or receive messages across chains.
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*/
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// slither-disable-next-line locked-ether
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contract AxelarGatewayDuplex is AxelarGatewaySource, AxelarGatewayDestination {
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/// @dev Initializes the contract with the Axelar gateway and the initial owner.
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constructor(
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IAxelarGateway gateway,
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address initialOwner
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) Ownable(initialOwner) AxelarGatewayBase(gateway) AxelarExecutable(address(gateway)) {}
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}

‎contracts/crosschain/axelar/AxelarGatewaySource.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.27;
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import {CAIP2} from "@openzeppelin/contracts/utils/CAIP2.sol";
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import {CAIP10} from "@openzeppelin/contracts/utils/CAIP10.sol";
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import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
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import {AxelarGatewayBase} from "./AxelarGatewayBase.sol";
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import {IERC7786GatewaySource} from "../interfaces/draft-IERC7786.sol";
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/**
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* @dev Implementation of an ERC-7786 gateway source adapter for the Axelar Network.
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*
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* The contract provides a way to send messages to a remote chain via the Axelar Network
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* using the {sendMessage} function.
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*/
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abstract contract AxelarGatewaySource is IERC7786GatewaySource, AxelarGatewayBase {
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using Strings for address;
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error UnsupportedNativeTransfer();
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/// @inheritdoc IERC7786GatewaySource
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function supportsAttribute(bytes4 /*selector*/) public pure returns (bool) {
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return false;
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}
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/// @inheritdoc IERC7786GatewaySource
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function sendMessage(
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string calldata destinationChain, // CAIP-2 chain identifier
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string calldata receiver, // CAIP-10 account address (does not include the chain identifier)
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bytes calldata payload,
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bytes[] calldata attributes
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) external payable returns (bytes32 outboxId) {
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require(msg.value == 0, UnsupportedNativeTransfer());
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// Use of `if () revert` syntax to avoid accessing attributes[0] if it's empty
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if (attributes.length > 0)
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revert UnsupportedAttribute(attributes[0].length < 0x04 ? bytes4(0) : bytes4(attributes[0][0:4]));
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// Create the package
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string memory sender = msg.sender.toChecksumHexString();
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bytes memory adapterPayload = abi.encode(sender, receiver, payload, attributes);
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// Emit event
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outboxId = bytes32(0); // Explicitly set to 0
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emit MessagePosted(
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outboxId,
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CAIP10.format(CAIP2.local(), sender),
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CAIP10.format(destinationChain, receiver),
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payload,
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attributes
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);
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// Send the message
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string memory axelarDestination = getEquivalentChain(destinationChain);
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string memory remoteGateway = getRemoteGateway(destinationChain);
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localGateway.callContract(axelarDestination, remoteGateway, adapterPayload);
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return outboxId;
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}
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}

‎contracts/crosschain/axelar/mocks/AxelarGatewayMock.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.27;
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import {IAxelarGateway} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/interfaces/IAxelarGateway.sol";
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import {IAxelarExecutable} from "@axelar-network/axelar-gmp-sdk-solidity/contracts/interfaces/IAxelarExecutable.sol";
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import {BitMaps} from "@openzeppelin/contracts/utils/structs/BitMaps.sol";
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import {Strings} from "@openzeppelin/contracts/utils/Strings.sol";
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contract AxelarGatewayMock {
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using Strings for address;
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using Strings for string;
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using BitMaps for BitMaps.BitMap;
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BitMaps.BitMap private pendingCommandIds;
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event CommandIdPending(
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bytes32 indexed commandId,
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string destinationChain,
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string destinationContractAddress,
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bytes payload
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);
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function callContract(
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string calldata destinationChain,
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string calldata destinationContractAddress,
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bytes calldata payload
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) external {
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// TODO: check that destination chain is local
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emit IAxelarGateway.ContractCall(
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msg.sender,
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destinationChain,
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destinationContractAddress,
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keccak256(payload),
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payload
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);
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bytes32 commandId = keccak256(
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abi.encode(
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destinationChain,
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msg.sender.toChecksumHexString(),
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destinationContractAddress,
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keccak256(payload)
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)
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);
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require(!pendingCommandIds.get(uint256(commandId)));
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pendingCommandIds.set(uint256(commandId));
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emit CommandIdPending(commandId, destinationChain, destinationContractAddress, payload);
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// NOTE: source chain and destination chain are the same in this mock
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address target = destinationContractAddress.parseAddress();
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IAxelarExecutable(target).execute(commandId, destinationChain, msg.sender.toChecksumHexString(), payload);
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}
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function validateContractCall(
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bytes32 commandId,
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string calldata sourceChain,
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string calldata sourceAddress,
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bytes32 payloadHash
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) external returns (bool) {
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if (pendingCommandIds.get(uint256(commandId))) {
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pendingCommandIds.unset(uint256(commandId));
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emit IAxelarGateway.ContractCallExecuted(commandId);
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return
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commandId ==
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keccak256(abi.encode(sourceChain, sourceAddress, msg.sender.toChecksumHexString(), payloadHash));
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} else return false;
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}
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}

‎contracts/crosschain/interfaces/draft-IERC7786.sol‎

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// SPDX-License-Identifier: MIT
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pragma solidity ^0.8.0;
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/**
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* @dev Interface for ERC-7786 source gateways.
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*
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* See ERC-7786 for more details
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*/
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interface IERC7786GatewaySource {
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/**
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* @dev Event emitted when a message is created. If `outboxId` is zero, no further processing is necessary. If
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* `outboxId` is not zero, then further (gateway specific, and non-standardized) action is required.
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*/
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event MessagePosted(
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bytes32 indexed outboxId,
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string sender, // CAIP-10 account identifier (chain identifier + ":" + account address)
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string receiver, // CAIP-10 account identifier (chain identifier + ":" + account address)
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bytes payload,
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bytes[] attributes
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);
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/// @dev This error is thrown when a message creation fails because of an unsupported attribute being specified.
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error UnsupportedAttribute(bytes4 selector);
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/// @dev Getter to check whether an attribute is supported or not.
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function supportsAttribute(bytes4 selector) external view returns (bool);
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/**
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* @dev Endpoint for creating a new message. If the message requires further (gateway specific) processing before
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* it can be sent to the destination chain, then a non-zero `outboxId` must be returned. Otherwise, the
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* message MUST be sent and this function must return 0.
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* @param destinationChain {CAIP2} chain identifier
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* @param receiver {CAIP10} account address (does not include the chain identifier)
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*
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* * MUST emit a {MessagePosted} event.
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*
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* If any of the `attributes` is not supported, this function SHOULD revert with an {UnsupportedAttribute} error.
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* Other errors SHOULD revert with errors not specified in ERC-7786.
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*/
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function sendMessage(
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string calldata destinationChain,
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string calldata receiver,
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bytes calldata payload,
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bytes[] calldata attributes
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) external payable returns (bytes32 outboxId);
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}
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/**
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* @dev Interface for the ERC-7786 client contract (receiver).
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*
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* See ERC-7786 for more details
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*/
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interface IERC7786Receiver {
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/**
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* @dev Endpoint for receiving cross-chain message.
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* @param sourceChain {CAIP2} chain identifier
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* @param sender {CAIP10} account address (does not include the chain identifier)
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*
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* This function may be called directly by the gateway.
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*/
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function executeMessage(
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string calldata sourceChain, // CAIP-2 chain identifier
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string calldata sender, // CAIP-10 account address (does not include the chain identifier)
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bytes calldata payload,
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bytes[] calldata attributes
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) external payable returns (bytes4);
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}

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