Contract Source Code:

// Sources flattened with hardhat v2.9.9 https://hardhat.org

// File contracts/interfaces/IAxelarGateway.sol

// SPDX-License-Identifier: MIT

pragma solidity 0.8.9;

interface IAxelarGateway {
    /**********\
    |* Errors *|
    \**********/

    error NotSelf();
    error NotProxy();
    error InvalidCodeHash();
    error SetupFailed();
    error InvalidAuthModule();
    error InvalidTokenDeployer();
    error InvalidAmount();
    error InvalidChainId();
    error InvalidCommands();
    error TokenDoesNotExist(string symbol);
    error TokenAlreadyExists(string symbol);
    error TokenDeployFailed(string symbol);
    error TokenContractDoesNotExist(address token);
    error BurnFailed(string symbol);
    error MintFailed(string symbol);
    error InvalidSetMintLimitsParams();
    error ExceedMintLimit(string symbol);

    /**********\
    |* Events *|
    \**********/

    event TokenSent(address indexed sender, string destinationChain, string destinationAddress, string symbol, uint256 amount);

    event ContractCall(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload
    );

    event ContractCallWithToken(
        address indexed sender,
        string destinationChain,
        string destinationContractAddress,
        bytes32 indexed payloadHash,
        bytes payload,
        string symbol,
        uint256 amount
    );

    event Executed(bytes32 indexed commandId);

    event TokenDeployed(string symbol, address tokenAddresses);

    event ContractCallApproved(
        bytes32 indexed commandId,
        string sourceChain,
        string sourceAddress,
        address indexed contractAddress,
        bytes32 indexed payloadHash,
        bytes32 sourceTxHash,
        uint256 sourceEventIndex
    );

    event ContractCallApprovedWithMint(
        bytes32 indexed commandId,
        string sourceChain,
        string sourceAddress,
        address indexed contractAddress,
        bytes32 indexed payloadHash,
        string symbol,
        uint256 amount,
        bytes32 sourceTxHash,
        uint256 sourceEventIndex
    );

    event TokenMintLimitUpdated(string symbol, uint256 limit);

    event OperatorshipTransferred(bytes newOperatorsData);

    event Upgraded(address indexed implementation);

    /********************\
    |* Public Functions *|
    \********************/

    function sendToken(
        string calldata destinationChain,
        string calldata destinationAddress,
        string calldata symbol,
        uint256 amount
    ) external;

    function callContract(
        string calldata destinationChain,
        string calldata contractAddress,
        bytes calldata payload
    ) external;

    function callContractWithToken(
        string calldata destinationChain,
        string calldata contractAddress,
        bytes calldata payload,
        string calldata symbol,
        uint256 amount
    ) external;

    function isContractCallApproved(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        address contractAddress,
        bytes32 payloadHash
    ) external view returns (bool);

    function isContractCallAndMintApproved(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        address contractAddress,
        bytes32 payloadHash,
        string calldata symbol,
        uint256 amount
    ) external view returns (bool);

    function validateContractCall(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes32 payloadHash
    ) external returns (bool);

    function validateContractCallAndMint(
        bytes32 commandId,
        string calldata sourceChain,
        string calldata sourceAddress,
        bytes32 payloadHash,
        string calldata symbol,
        uint256 amount
    ) external returns (bool);

    /***********\
    |* Getters *|
    \***********/

    function authModule() external view returns (address);

    function tokenDeployer() external view returns (address);

    function tokenMintLimit(string memory symbol) external view returns (uint256);

    function tokenMintAmount(string memory symbol) external view returns (uint256);

    function allTokensFrozen() external view returns (bool);

    function implementation() external view returns (address);

    function tokenAddresses(string memory symbol) external view returns (address);

    function tokenFrozen(string memory symbol) external view returns (bool);

    function isCommandExecuted(bytes32 commandId) external view returns (bool);

    function adminEpoch() external view returns (uint256);

    function adminThreshold(uint256 epoch) external view returns (uint256);

    function admins(uint256 epoch) external view returns (address[] memory);

    /*******************\
    |* Admin Functions *|
    \*******************/

    function setTokenMintLimits(string[] calldata symbols, uint256[] calldata limits) external;

    function upgrade(
        address newImplementation,
        bytes32 newImplementationCodeHash,
        bytes calldata setupParams
    ) external;

    /**********************\
    |* External Functions *|
    \**********************/

    function setup(bytes calldata params) external;

    function execute(bytes calldata input) external;
}


// File contracts/interfaces/IERC20Burn.sol


interface IERC20Burn {
    function burn(bytes32 salt) external;
}


// File contracts/interfaces/IERC20BurnFrom.sol


interface IERC20BurnFrom {
    function burnFrom(address account, uint256 amount) external;
}


// File contracts/interfaces/IERC20.sol


/**
 * @dev Interface of the ERC20 standard as defined in the EIP.
 */
interface IERC20 {
    error InvalidAccount();

    /**
     * @dev Returns the amount of tokens in existence.
     */
    function totalSupply() external view returns (uint256);

    /**
     * @dev Returns the amount of tokens owned by `account`.
     */
    function balanceOf(address account) external view returns (uint256);

    /**
     * @dev Moves `amount` tokens from the caller's account to `recipient`.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transfer(address recipient, uint256 amount) external returns (bool);

    /**
     * @dev Returns the remaining number of tokens that `spender` will be
     * allowed to spend on behalf of `owner` through {transferFrom}. This is
     * zero by default.
     *
     * This value changes when {approve} or {transferFrom} are called.
     */
    function allowance(address owner, address spender) external view returns (uint256);

    /**
     * @dev Sets `amount` as the allowance of `spender` over the caller's tokens.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * IMPORTANT: Beware that changing an allowance with this method brings the risk
     * that someone may use both the old and the new allowance by unfortunate
     * transaction ordering. One possible solution to mitigate this race
     * condition is to first reduce the spender's allowance to 0 and set the
     * desired value afterwards:
     * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
     *
     * Emits an {Approval} event.
     */
    function approve(address spender, uint256 amount) external returns (bool);

    /**
     * @dev Moves `amount` tokens from `sender` to `recipient` using the
     * allowance mechanism. `amount` is then deducted from the caller's
     * allowance.
     *
     * Returns a boolean value indicating whether the operation succeeded.
     *
     * Emits a {Transfer} event.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external returns (bool);

    /**
     * @dev Emitted when `value` tokens are moved from one account (`from`) to
     * another (`to`).
     *
     * Note that `value` may be zero.
     */
    event Transfer(address indexed from, address indexed to, uint256 value);

    /**
     * @dev Emitted when the allowance of a `spender` for an `owner` is set by
     * a call to {approve}. `value` is the new allowance.
     */
    event Approval(address indexed owner, address indexed spender, uint256 value);
}


// File contracts/interfaces/IERC20Permit.sol


interface IERC20Permit {
    function DOMAIN_SEPARATOR() external view returns (bytes32);

    function nonces(address account) external view returns (uint256);

    function permit(
        address issuer,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external;
}


// File contracts/interfaces/IOwnable.sol


interface IOwnable {
    error NotOwner();
    error InvalidOwner();

    event OwnershipTransferred(address indexed previousOwner, address indexed newOwner);

    function owner() external view returns (address);

    function transferOwnership(address newOwner) external;
}


// File contracts/interfaces/IMintableCappedERC20.sol


interface IMintableCappedERC20 is IERC20, IERC20Permit, IOwnable {
    error CapExceeded();

    function cap() external view returns (uint256);

    function mint(address account, uint256 amount) external;
}


// File contracts/interfaces/IBurnableMintableCappedERC20.sol


interface IBurnableMintableCappedERC20 is IERC20Burn, IERC20BurnFrom, IMintableCappedERC20 {
    function depositAddress(bytes32 salt) external view returns (address);

    function burn(bytes32 salt) external;

    function burnFrom(address account, uint256 amount) external;
}


// File contracts/ERC20.sol


/**
 * @dev Implementation of the {IERC20} interface.
 *
 * This implementation is agnostic to the way tokens are created. This means
 * that a supply mechanism has to be added in a derived contract using {_mint}.
 * For a generic mechanism see {ERC20PresetMinterPauser}.
 *
 * TIP: For a detailed writeup see our guide
 * https://forum.zeppelin.solutions/t/how-to-implement-erc20-supply-mechanisms/226[How
 * to implement supply mechanisms].
 *
 * We have followed general OpenZeppelin guidelines: functions revert instead
 * of returning `false` on failure. This behavior is nonetheless conventional
 * and does not conflict with the expectations of ERC20 applications.
 *
 * Additionally, an {Approval} event is emitted on calls to {transferFrom}.
 * This allows applications to reconstruct the allowance for all accounts just
 * by listening to said events. Other implementations of the EIP may not emit
 * these events, as it isn't required by the specification.
 *
 * Finally, the non-standard {decreaseAllowance} and {increaseAllowance}
 * functions have been added to mitigate the well-known issues around setting
 * allowances. See {IERC20-approve}.
 */
contract ERC20 is IERC20 {
    mapping(address => uint256) public override balanceOf;

    mapping(address => mapping(address => uint256)) public override allowance;

    uint256 public override totalSupply;

    string public name;
    string public symbol;

    uint8 public immutable decimals;

    /**
     * @dev Sets the values for {name}, {symbol}, and {decimals}.
     */
    constructor(
        string memory name_,
        string memory symbol_,
        uint8 decimals_
    ) {
        name = name_;
        symbol = symbol_;
        decimals = decimals_;
    }

    /**
     * @dev See {IERC20-transfer}.
     *
     * Requirements:
     *
     * - `recipient` cannot be the zero address.
     * - the caller must have a balance of at least `amount`.
     */
    function transfer(address recipient, uint256 amount) external virtual override returns (bool) {
        _transfer(msg.sender, recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * NOTE: If `amount` is the maximum `uint256`, the allowance is not updated on
     * `transferFrom`. This is semantically equivalent to an infinite approval.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) external virtual override returns (bool) {
        _approve(msg.sender, spender, amount);
        return true;
    }

    /**
     * @dev See {IERC20-transferFrom}.
     *
     * Emits an {Approval} event indicating the updated allowance. This is not
     * required by the EIP. See the note at the beginning of {ERC20}.
     *
     * Requirements:
     *
     * - `sender` and `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     * - the caller must have allowance for ``sender``'s tokens of at least
     * `amount`.
     */
    function transferFrom(
        address sender,
        address recipient,
        uint256 amount
    ) external virtual override returns (bool) {
        uint256 _allowance = allowance[sender][msg.sender];

        if (_allowance != type(uint256).max) {
            _approve(sender, msg.sender, _allowance - amount);
        }

        _transfer(sender, recipient, amount);

        return true;
    }

    /**
     * @dev Atomically increases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function increaseAllowance(address spender, uint256 addedValue) external virtual returns (bool) {
        _approve(msg.sender, spender, allowance[msg.sender][spender] + addedValue);
        return true;
    }

    /**
     * @dev Atomically decreases the allowance granted to `spender` by the caller.
     *
     * This is an alternative to {approve} that can be used as a mitigation for
     * problems described in {IERC20-approve}.
     *
     * Emits an {Approval} event indicating the updated allowance.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     * - `spender` must have allowance for the caller of at least
     * `subtractedValue`.
     */
    function decreaseAllowance(address spender, uint256 subtractedValue) external virtual returns (bool) {
        _approve(msg.sender, spender, allowance[msg.sender][spender] - subtractedValue);
        return true;
    }

    /**
     * @dev Moves tokens `amount` from `sender` to `recipient`.
     *
     * This is internal function is equivalent to {transfer}, and can be used to
     * e.g. implement automatic token fees, slashing mechanisms, etc.
     *
     * Emits a {Transfer} event.
     *
     * Requirements:
     *
     * - `sender` cannot be the zero address.
     * - `recipient` cannot be the zero address.
     * - `sender` must have a balance of at least `amount`.
     */
    function _transfer(
        address sender,
        address recipient,
        uint256 amount
    ) internal virtual {
        if (sender == address(0) || recipient == address(0)) revert InvalidAccount();

        balanceOf[sender] -= amount;
        balanceOf[recipient] += amount;
        emit Transfer(sender, recipient, amount);
    }

    /** @dev Creates `amount` tokens and assigns them to `account`, increasing
     * the total supply.
     *
     * Emits a {Transfer} event with `from` set to the zero address.
     *
     * Requirements:
     *
     * - `to` cannot be the zero address.
     */
    function _mint(address account, uint256 amount) internal virtual {
        if (account == address(0)) revert InvalidAccount();

        totalSupply += amount;
        balanceOf[account] += amount;
        emit Transfer(address(0), account, amount);
    }

    /**
     * @dev Destroys `amount` tokens from `account`, reducing the
     * total supply.
     *
     * Emits a {Transfer} event with `to` set to the zero address.
     *
     * Requirements:
     *
     * - `account` cannot be the zero address.
     * - `account` must have at least `amount` tokens.
     */
    function _burn(address account, uint256 amount) internal virtual {
        if (account == address(0)) revert InvalidAccount();

        balanceOf[account] -= amount;
        totalSupply -= amount;
        emit Transfer(account, address(0), amount);
    }

    /**
     * @dev Sets `amount` as the allowance of `spender` over the `owner` s tokens.
     *
     * This internal function is equivalent to `approve`, and can be used to
     * e.g. set automatic allowances for certain subsystems, etc.
     *
     * Emits an {Approval} event.
     *
     * Requirements:
     *
     * - `owner` cannot be the zero address.
     * - `spender` cannot be the zero address.
     */
    function _approve(
        address owner,
        address spender,
        uint256 amount
    ) internal virtual {
        if (owner == address(0) || spender == address(0)) revert InvalidAccount();

        allowance[owner][spender] = amount;
        emit Approval(owner, spender, amount);
    }
}


// File contracts/ERC20Permit.sol


abstract contract ERC20Permit is IERC20, IERC20Permit, ERC20 {
    error PermitExpired();
    error InvalidS();
    error InvalidV();
    error InvalidSignature();

    bytes32 public immutable DOMAIN_SEPARATOR;

    string private constant EIP191_PREFIX_FOR_EIP712_STRUCTURED_DATA = '\x19\x01';

    // keccak256('EIP712Domain(string name,string version,uint256 chainId,address verifyingContract)')
    bytes32 private constant DOMAIN_TYPE_SIGNATURE_HASH = bytes32(0x8b73c3c69bb8fe3d512ecc4cf759cc79239f7b179b0ffacaa9a75d522b39400f);

    // keccak256('Permit(address owner,address spender,uint256 value,uint256 nonce,uint256 deadline)')
    bytes32 private constant PERMIT_SIGNATURE_HASH = bytes32(0x6e71edae12b1b97f4d1f60370fef10105fa2faae0126114a169c64845d6126c9);

    mapping(address => uint256) public nonces;

    constructor(string memory name) {
        DOMAIN_SEPARATOR = keccak256(
            abi.encode(DOMAIN_TYPE_SIGNATURE_HASH, keccak256(bytes(name)), keccak256(bytes('1')), block.chainid, address(this))
        );
    }

    function permit(
        address issuer,
        address spender,
        uint256 value,
        uint256 deadline,
        uint8 v,
        bytes32 r,
        bytes32 s
    ) external {
        if (block.timestamp > deadline) revert PermitExpired();

        if (uint256(s) > 0x7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0) revert InvalidS();

        if (v != 27 && v != 28) revert InvalidV();

        bytes32 digest = keccak256(
            abi.encodePacked(
                EIP191_PREFIX_FOR_EIP712_STRUCTURED_DATA,
                DOMAIN_SEPARATOR,
                keccak256(abi.encode(PERMIT_SIGNATURE_HASH, issuer, spender, value, nonces[issuer]++, deadline))
            )
        );

        address recoveredAddress = ecrecover(digest, v, r, s);

        if (recoveredAddress != issuer) revert InvalidSignature();

        // _approve will revert if issuer is address(0x0)
        _approve(issuer, spender, value);
    }
}


// File contracts/Ownable.sol


abstract contract Ownable is IOwnable {
    address public owner;

    constructor() {
        owner = msg.sender;
        emit OwnershipTransferred(address(0), msg.sender);
    }

    modifier onlyOwner() {
        if (owner != msg.sender) revert NotOwner();

        _;
    }

    function transferOwnership(address newOwner) external virtual onlyOwner {
        if (newOwner == address(0)) revert InvalidOwner();

        emit OwnershipTransferred(owner, newOwner);
        owner = newOwner;
    }
}


// File contracts/MintableCappedERC20.sol


contract MintableCappedERC20 is IMintableCappedERC20, ERC20, ERC20Permit, Ownable {
    uint256 public immutable cap;

    constructor(
        string memory name,
        string memory symbol,
        uint8 decimals,
        uint256 capacity
    ) ERC20(name, symbol, decimals) ERC20Permit(name) Ownable() {
        cap = capacity;
    }

    function mint(address account, uint256 amount) external onlyOwner {
        uint256 capacity = cap;

        _mint(account, amount);

        if (capacity == 0) return;

        if (totalSupply > capacity) revert CapExceeded();
    }
}


// File contracts/DepositHandler.sol


contract DepositHandler {
    error IsLocked();
    error NotContract();

    uint256 internal constant IS_NOT_LOCKED = uint256(1);
    uint256 internal constant IS_LOCKED = uint256(2);

    uint256 internal _lockedStatus = IS_NOT_LOCKED;

    modifier noReenter() {
        if (_lockedStatus == IS_LOCKED) revert IsLocked();

        _lockedStatus = IS_LOCKED;
        _;
        _lockedStatus = IS_NOT_LOCKED;
    }

    function execute(address callee, bytes calldata data) external noReenter returns (bool success, bytes memory returnData) {
        if (callee.code.length == 0) revert NotContract();
        (success, returnData) = callee.call(data);
    }

    // NOTE: The gateway should always destroy the `DepositHandler` in the same runtime context that deploys it.
    function destroy(address etherDestination) external noReenter {
        selfdestruct(payable(etherDestination));
    }
}


// File contracts/BurnableMintableCappedERC20.sol


contract BurnableMintableCappedERC20 is IBurnableMintableCappedERC20, MintableCappedERC20 {
    constructor(
        string memory name,
        string memory symbol,
        uint8 decimals,
        uint256 capacity
    ) MintableCappedERC20(name, symbol, decimals, capacity) {}

    function depositAddress(bytes32 salt) public view returns (address) {
        /* Convert a hash which is bytes32 to an address which is 20-byte long
        according to https://docs.soliditylang.org/en/v0.8.1/control-structures.html?highlight=create2#salted-contract-creations-create2 */
        return
            address(
                uint160(
                    uint256(
                        keccak256(
                            abi.encodePacked(bytes1(0xff), owner, salt, keccak256(abi.encodePacked(type(DepositHandler).creationCode)))
                        )
                    )
                )
            );
    }

    function burn(bytes32 salt) external onlyOwner {
        address account = depositAddress(salt);
        _burn(account, balanceOf[account]);
    }

    function burnFrom(address account, uint256 amount) external onlyOwner {
        uint256 _allowance = allowance[account][msg.sender];
        if (_allowance != type(uint256).max) {
            _approve(account, msg.sender, _allowance - amount);
        }
        _burn(account, amount);
    }
}