previousOwner

newOwner

OwnershipTransferred

owner

renounceOwnership

transferOwnership

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "../utils/ContextUpgradeable.sol";
import "../proxy/Initializable.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract OwnableUpgradeable is Initializable, ContextUpgradeable {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    function __Ownable_init() internal initializer {
        __Context_init_unchained();
        __Ownable_init_unchained();
    }

    function __Ownable_init_unchained() internal initializer {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
    uint256[49] private __gap;
}


OwnableUpgradeable

// SPDX-License-Identifier: MIT

// solhint-disable-next-line compiler-version
pragma solidity >=0.4.24 <0.8.0;

import "../utils/AddressUpgradeable.sol";

/**
 * @dev This is a base contract to aid in writing upgradeable contracts, or any kind of contract that will be deployed
 * behind a proxy. Since a proxied contract can't have a constructor, it's common to move constructor logic to an
 * external initializer function, usually called `initialize`. It then becomes necessary to protect this initializer
 * function so it can only be called once. The {initializer} modifier provided by this contract will have this effect.
 *
 * TIP: To avoid leaving the proxy in an uninitialized state, the initializer function should be called as early as
 * possible by providing the encoded function call as the `_data` argument to {UpgradeableProxy-constructor}.
 *
 * CAUTION: When used with inheritance, manual care must be taken to not invoke a parent initializer twice, or to ensure
 * that all initializers are idempotent. This is not verified automatically as constructors are by Solidity.
 */
abstract contract Initializable {

    /**
     * @dev Indicates that the contract has been initialized.
     */
    bool private _initialized;

    /**
     * @dev Indicates that the contract is in the process of being initialized.
     */
    bool private _initializing;

    /**
     * @dev Modifier to protect an initializer function from being invoked twice.
     */
    modifier initializer() {
        require(_initializing || _isConstructor() || !_initialized, "Initializable: contract is already initialized");

        bool isTopLevelCall = !_initializing;
        if (isTopLevelCall) {
            _initializing = true;
            _initialized = true;
        }

        _;

        if (isTopLevelCall) {
            _initializing = false;
        }
    }

    /// @dev Returns true if and only if the function is running in the constructor
    function _isConstructor() private view returns (bool) {
        return !AddressUpgradeable.isContract(address(this));
    }
}


Initializable

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Collection of functions related to the address type
 */
library AddressUpgradeable {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


AddressUpgradeable

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;
import "../proxy/Initializable.sol";

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract ContextUpgradeable is Initializable {
    function __Context_init() internal initializer {
        __Context_init_unchained();
    }

    function __Context_init_unchained() internal initializer {
    }
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
    uint256[50] private __gap;
}


ContextUpgradeable

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "../utils/Context.sol";
/**
 * @dev Contract module which provides a basic access control mechanism, where
 * there is an account (an owner) that can be granted exclusive access to
 * specific functions.
 *
 * By default, the owner account will be the one that deploys the contract. This
 * can later be changed with {transferOwnership}.
 *
 * This module is used through inheritance. It will make available the modifier
 * `onlyOwner`, which can be applied to your functions to restrict their use to
 * the owner.
 */
abstract contract Ownable is Context {
    address private _owner;

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

    /**
     * @dev Initializes the contract setting the deployer as the initial owner.
     */
    constructor () {
        address msgSender = _msgSender();
        _owner = msgSender;
        emit OwnershipTransferred(address(0), msgSender);
    }

    /**
     * @dev Returns the address of the current owner.
     */
    function owner() public view virtual returns (address) {
        return _owner;
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
        _;
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions anymore. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby removing any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        emit OwnershipTransferred(_owner, address(0));
        _owner = address(0);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Can only be called by the current owner.
     */
    function transferOwnership(address newOwner) public virtual onlyOwner {
        require(newOwner != address(0), "Ownable: new owner is the zero address");
        emit OwnershipTransferred(_owner, newOwner);
        _owner = newOwner;
    }
}


Ownable

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Wrappers over Solidity's arithmetic operations with added overflow
 * checks.
 *
 * Arithmetic operations in Solidity wrap on overflow. This can easily result
 * in bugs, because programmers usually assume that an overflow raises an
 * error, which is the standard behavior in high level programming languages.
 * `SafeMath` restores this intuition by reverting the transaction when an
 * operation overflows.
 *
 * Using this library instead of the unchecked operations eliminates an entire
 * class of bugs, so it's recommended to use it always.
 */
library SafeMath {
    /**
     * @dev Returns the addition of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryAdd(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        uint256 c = a + b;
        if (c < a) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the substraction of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function trySub(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b > a) return (false, 0);
        return (true, a - b);
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, with an overflow flag.
     *
     * _Available since v3.4._
     */
    function tryMul(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        // Gas optimization: this is cheaper than requiring 'a' not being zero, but the
        // benefit is lost if 'b' is also tested.
        // See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
        if (a == 0) return (true, 0);
        uint256 c = a * b;
        if (c / a != b) return (false, 0);
        return (true, c);
    }

    /**
     * @dev Returns the division of two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryDiv(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a / b);
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers, with a division by zero flag.
     *
     * _Available since v3.4._
     */
    function tryMod(uint256 a, uint256 b) internal pure returns (bool, uint256) {
        if (b == 0) return (false, 0);
        return (true, a % b);
    }

    /**
     * @dev Returns the addition of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `+` operator.
     *
     * Requirements:
     *
     * - Addition cannot overflow.
     */
    function add(uint256 a, uint256 b) internal pure returns (uint256) {
        uint256 c = a + b;
        require(c >= a, "SafeMath: addition overflow");
        return c;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting on
     * overflow (when the result is negative).
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b <= a, "SafeMath: subtraction overflow");
        return a - b;
    }

    /**
     * @dev Returns the multiplication of two unsigned integers, reverting on
     * overflow.
     *
     * Counterpart to Solidity's `*` operator.
     *
     * Requirements:
     *
     * - Multiplication cannot overflow.
     */
    function mul(uint256 a, uint256 b) internal pure returns (uint256) {
        if (a == 0) return 0;
        uint256 c = a * b;
        require(c / a == b, "SafeMath: multiplication overflow");
        return c;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting on
     * division by zero. The result is rounded towards zero.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: division by zero");
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting when dividing by zero.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b) internal pure returns (uint256) {
        require(b > 0, "SafeMath: modulo by zero");
        return a % b;
    }

    /**
     * @dev Returns the subtraction of two unsigned integers, reverting with custom message on
     * overflow (when the result is negative).
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {trySub}.
     *
     * Counterpart to Solidity's `-` operator.
     *
     * Requirements:
     *
     * - Subtraction cannot overflow.
     */
    function sub(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b <= a, errorMessage);
        return a - b;
    }

    /**
     * @dev Returns the integer division of two unsigned integers, reverting with custom message on
     * division by zero. The result is rounded towards zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryDiv}.
     *
     * Counterpart to Solidity's `/` operator. Note: this function uses a
     * `revert` opcode (which leaves remaining gas untouched) while Solidity
     * uses an invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function div(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a / b;
    }

    /**
     * @dev Returns the remainder of dividing two unsigned integers. (unsigned integer modulo),
     * reverting with custom message when dividing by zero.
     *
     * CAUTION: This function is deprecated because it requires allocating memory for the error
     * message unnecessarily. For custom revert reasons use {tryMod}.
     *
     * Counterpart to Solidity's `%` operator. This function uses a `revert`
     * opcode (which leaves remaining gas untouched) while Solidity uses an
     * invalid opcode to revert (consuming all remaining gas).
     *
     * Requirements:
     *
     * - The divisor cannot be zero.
     */
    function mod(uint256 a, uint256 b, string memory errorMessage) internal pure returns (uint256) {
        require(b > 0, errorMessage);
        return a % b;
    }
}


SafeMath

name_

symbol_

spender

value

Approval

from

Transfer

allowance

amount

approve

account

balanceOf

decimals

subtractedValue

decreaseAllowance

addedValue

increaseAllowance

name

symbol

totalSupply

recipient

transfer

sender

transferFrom

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "../../utils/Context.sol";
import "./IERC20.sol";
import "../../math/SafeMath.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 Context, IERC20 {
    using SafeMath for uint256;

    mapping (address => uint256) private _balances;

    mapping (address => mapping (address => uint256)) private _allowances;

    uint256 private _totalSupply;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    /**
     * @dev Sets the values for {name} and {symbol}, initializes {decimals} with
     * a default value of 18.
     *
     * To select a different value for {decimals}, use {_setupDecimals}.
     *
     * All three of these values are immutable: they can only be set once during
     * construction.
     */
    constructor (string memory name_, string memory symbol_) {
        _name = name_;
        _symbol = symbol_;
        _decimals = 18;
    }

    /**
     * @dev Returns the name of the token.
     */
    function name() public view virtual returns (string memory) {
        return _name;
    }

    /**
     * @dev Returns the symbol of the token, usually a shorter version of the
     * name.
     */
    function symbol() public view virtual returns (string memory) {
        return _symbol;
    }

    /**
     * @dev Returns the number of decimals used to get its user representation.
     * For example, if `decimals` equals `2`, a balance of `505` tokens should
     * be displayed to a user as `5,05` (`505 / 10 ** 2`).
     *
     * Tokens usually opt for a value of 18, imitating the relationship between
     * Ether and Wei. This is the value {ERC20} uses, unless {_setupDecimals} is
     * called.
     *
     * NOTE: This information is only used for _display_ purposes: it in
     * no way affects any of the arithmetic of the contract, including
     * {IERC20-balanceOf} and {IERC20-transfer}.
     */
    function decimals() public view virtual returns (uint8) {
        return _decimals;
    }

    /**
     * @dev See {IERC20-totalSupply}.
     */
    function totalSupply() public view virtual override returns (uint256) {
        return _totalSupply;
    }

    /**
     * @dev See {IERC20-balanceOf}.
     */
    function balanceOf(address account) public view virtual override returns (uint256) {
        return _balances[account];
    }

    /**
     * @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) public virtual override returns (bool) {
        _transfer(_msgSender(), recipient, amount);
        return true;
    }

    /**
     * @dev See {IERC20-allowance}.
     */
    function allowance(address owner, address spender) public view virtual override returns (uint256) {
        return _allowances[owner][spender];
    }

    /**
     * @dev See {IERC20-approve}.
     *
     * Requirements:
     *
     * - `spender` cannot be the zero address.
     */
    function approve(address spender, uint256 amount) public virtual override returns (bool) {
        _approve(_msgSender(), 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) public virtual override returns (bool) {
        _transfer(sender, recipient, amount);
        _approve(sender, _msgSender(), _allowances[sender][_msgSender()].sub(amount, "ERC20: transfer amount exceeds allowance"));
        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) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].add(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) public virtual returns (bool) {
        _approve(_msgSender(), spender, _allowances[_msgSender()][spender].sub(subtractedValue, "ERC20: decreased allowance below zero"));
        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 {
        require(sender != address(0), "ERC20: transfer from the zero address");
        require(recipient != address(0), "ERC20: transfer to the zero address");

        _beforeTokenTransfer(sender, recipient, amount);

        _balances[sender] = _balances[sender].sub(amount, "ERC20: transfer amount exceeds balance");
        _balances[recipient] = _balances[recipient].add(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 {
        require(account != address(0), "ERC20: mint to the zero address");

        _beforeTokenTransfer(address(0), account, amount);

        _totalSupply = _totalSupply.add(amount);
        _balances[account] = _balances[account].add(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 {
        require(account != address(0), "ERC20: burn from the zero address");

        _beforeTokenTransfer(account, address(0), amount);

        _balances[account] = _balances[account].sub(amount, "ERC20: burn amount exceeds balance");
        _totalSupply = _totalSupply.sub(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 {
        require(owner != address(0), "ERC20: approve from the zero address");
        require(spender != address(0), "ERC20: approve to the zero address");

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

    /**
     * @dev Sets {decimals} to a value other than the default one of 18.
     *
     * WARNING: This function should only be called from the constructor. Most
     * applications that interact with token contracts will not expect
     * {decimals} to ever change, and may work incorrectly if it does.
     */
    function _setupDecimals(uint8 decimals_) internal virtual {
        _decimals = decimals_;
    }

    /**
     * @dev Hook that is called before any transfer of tokens. This includes
     * minting and burning.
     *
     * Calling conditions:
     *
     * - when `from` and `to` are both non-zero, `amount` of ``from``'s tokens
     * will be to transferred to `to`.
     * - when `from` is zero, `amount` tokens will be minted for `to`.
     * - when `to` is zero, `amount` of ``from``'s tokens will be burned.
     * - `from` and `to` are never both zero.
     *
     * To learn more about hooks, head to xref:ROOT:extending-contracts.adoc#using-hooks[Using Hooks].
     */
    function _beforeTokenTransfer(address from, address to, uint256 amount) internal virtual { }
}


ERC20

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

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


IERC20

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

import "./IERC20.sol";
import "../../math/SafeMath.sol";
import "../../utils/Address.sol";

/**
 * @title SafeERC20
 * @dev Wrappers around ERC20 operations that throw on failure (when the token
 * contract returns false). Tokens that return no value (and instead revert or
 * throw on failure) are also supported, non-reverting calls are assumed to be
 * successful.
 * To use this library you can add a `using SafeERC20 for IERC20;` statement to your contract,
 * which allows you to call the safe operations as `token.safeTransfer(...)`, etc.
 */
library SafeERC20 {
    using SafeMath for uint256;
    using Address for address;

    function safeTransfer(IERC20 token, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transfer.selector, to, value));
    }

    function safeTransferFrom(IERC20 token, address from, address to, uint256 value) internal {
        _callOptionalReturn(token, abi.encodeWithSelector(token.transferFrom.selector, from, to, value));
    }

    /**
     * @dev Deprecated. This function has issues similar to the ones found in
     * {IERC20-approve}, and its usage is discouraged.
     *
     * Whenever possible, use {safeIncreaseAllowance} and
     * {safeDecreaseAllowance} instead.
     */
    function safeApprove(IERC20 token, address spender, uint256 value) internal {
        // safeApprove should only be called when setting an initial allowance,
        // or when resetting it to zero. To increase and decrease it, use
        // 'safeIncreaseAllowance' and 'safeDecreaseAllowance'
        // solhint-disable-next-line max-line-length
        require((value == 0) || (token.allowance(address(this), spender) == 0),
            "SafeERC20: approve from non-zero to non-zero allowance"
        );
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, value));
    }

    function safeIncreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).add(value);
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    function safeDecreaseAllowance(IERC20 token, address spender, uint256 value) internal {
        uint256 newAllowance = token.allowance(address(this), spender).sub(value, "SafeERC20: decreased allowance below zero");
        _callOptionalReturn(token, abi.encodeWithSelector(token.approve.selector, spender, newAllowance));
    }

    /**
     * @dev Imitates a Solidity high-level call (i.e. a regular function call to a contract), relaxing the requirement
     * on the return value: the return value is optional (but if data is returned, it must not be false).
     * @param token The token targeted by the call.
     * @param data The call data (encoded using abi.encode or one of its variants).
     */
    function _callOptionalReturn(IERC20 token, bytes memory data) private {
        // We need to perform a low level call here, to bypass Solidity's return data size checking mechanism, since
        // we're implementing it ourselves. We use {Address.functionCall} to perform this call, which verifies that
        // the target address contains contract code and also asserts for success in the low-level call.

        bytes memory returndata = address(token).functionCall(data, "SafeERC20: low-level call failed");
        if (returndata.length > 0) { // Return data is optional
            // solhint-disable-next-line max-line-length
            require(abi.decode(returndata, (bool)), "SafeERC20: ERC20 operation did not succeed");
        }
    }
}


SafeERC20

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Collection of functions related to the address type
 */
library Address {
    /**
     * @dev Returns true if `account` is a contract.
     *
     * [IMPORTANT]
     * ====
     * It is unsafe to assume that an address for which this function returns
     * false is an externally-owned account (EOA) and not a contract.
     *
     * Among others, `isContract` will return false for the following
     * types of addresses:
     *
     *  - an externally-owned account
     *  - a contract in construction
     *  - an address where a contract will be created
     *  - an address where a contract lived, but was destroyed
     * ====
     */
    function isContract(address account) internal view returns (bool) {
        // This method relies on extcodesize, which returns 0 for contracts in
        // construction, since the code is only stored at the end of the
        // constructor execution.

        uint256 size;
        // solhint-disable-next-line no-inline-assembly
        assembly { size := extcodesize(account) }
        return size > 0;
    }

    /**
     * @dev Replacement for Solidity's `transfer`: sends `amount` wei to
     * `recipient`, forwarding all available gas and reverting on errors.
     *
     * https://eips.ethereum.org/EIPS/eip-1884[EIP1884] increases the gas cost
     * of certain opcodes, possibly making contracts go over the 2300 gas limit
     * imposed by `transfer`, making them unable to receive funds via
     * `transfer`. {sendValue} removes this limitation.
     *
     * https://diligence.consensys.net/posts/2019/09/stop-using-soliditys-transfer-now/[Learn more].
     *
     * IMPORTANT: because control is transferred to `recipient`, care must be
     * taken to not create reentrancy vulnerabilities. Consider using
     * {ReentrancyGuard} or the
     * https://solidity.readthedocs.io/en/v0.5.11/security-considerations.html#use-the-checks-effects-interactions-pattern[checks-effects-interactions pattern].
     */
    function sendValue(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        // solhint-disable-next-line avoid-low-level-calls, avoid-call-value
        (bool success, ) = recipient.call{ value: amount }("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }

    /**
     * @dev Performs a Solidity function call using a low level `call`. A
     * plain`call` is an unsafe replacement for a function call: use this
     * function instead.
     *
     * If `target` reverts with a revert reason, it is bubbled up by this
     * function (like regular Solidity function calls).
     *
     * Returns the raw returned data. To convert to the expected return value,
     * use https://solidity.readthedocs.io/en/latest/units-and-global-variables.html?highlight=abi.decode#abi-encoding-and-decoding-functions[`abi.decode`].
     *
     * Requirements:
     *
     * - `target` must be a contract.
     * - calling `target` with `data` must not revert.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data) internal returns (bytes memory) {
      return functionCall(target, data, "Address: low-level call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`], but with
     * `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        return functionCallWithValue(target, data, 0, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but also transferring `value` wei to `target`.
     *
     * Requirements:
     *
     * - the calling contract must have an ETH balance of at least `value`.
     * - the called Solidity function must be `payable`.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value) internal returns (bytes memory) {
        return functionCallWithValue(target, data, value, "Address: low-level call with value failed");
    }

    /**
     * @dev Same as {xref-Address-functionCallWithValue-address-bytes-uint256-}[`functionCallWithValue`], but
     * with `errorMessage` as a fallback revert reason when `target` reverts.
     *
     * _Available since v3.1._
     */
    function functionCallWithValue(address target, bytes memory data, uint256 value, string memory errorMessage) internal returns (bytes memory) {
        require(address(this).balance >= value, "Address: insufficient balance for call");
        require(isContract(target), "Address: call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.call{ value: value }(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data) internal view returns (bytes memory) {
        return functionStaticCall(target, data, "Address: low-level static call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a static call.
     *
     * _Available since v3.3._
     */
    function functionStaticCall(address target, bytes memory data, string memory errorMessage) internal view returns (bytes memory) {
        require(isContract(target), "Address: static call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.staticcall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data) internal returns (bytes memory) {
        return functionDelegateCall(target, data, "Address: low-level delegate call failed");
    }

    /**
     * @dev Same as {xref-Address-functionCall-address-bytes-string-}[`functionCall`],
     * but performing a delegate call.
     *
     * _Available since v3.4._
     */
    function functionDelegateCall(address target, bytes memory data, string memory errorMessage) internal returns (bytes memory) {
        require(isContract(target), "Address: delegate call to non-contract");

        // solhint-disable-next-line avoid-low-level-calls
        (bool success, bytes memory returndata) = target.delegatecall(data);
        return _verifyCallResult(success, returndata, errorMessage);
    }

    function _verifyCallResult(bool success, bytes memory returndata, string memory errorMessage) private pure returns(bytes memory) {
        if (success) {
            return returndata;
        } else {
            // Look for revert reason and bubble it up if present
            if (returndata.length > 0) {
                // The easiest way to bubble the revert reason is using memory via assembly

                // solhint-disable-next-line no-inline-assembly
                assembly {
                    let returndata_size := mload(returndata)
                    revert(add(32, returndata), returndata_size)
                }
            } else {
                revert(errorMessage);
            }
        }
    }
}


Address

// SPDX-License-Identifier: MIT

pragma solidity >=0.6.0 <0.8.0;

/*
 * @dev Provides information about the current execution context, including the
 * sender of the transaction and its data. While these are generally available
 * via msg.sender and msg.data, they should not be accessed in such a direct
 * manner, since when dealing with GSN meta-transactions the account sending and
 * paying for execution may not be the actual sender (as far as an application
 * is concerned).
 *
 * This contract is only required for intermediate, library-like contracts.
 */
abstract contract Context {
    function _msgSender() internal view virtual returns (address payable) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes memory) {
        this; // silence state mutability warning without generating bytecode - see https://github.com/ethereum/solidity/issues/2691
        return msg.data;
    }
}


Context

// SPDX-License-Identifier: MIT

pragma solidity ^0.7.0;

/**
 * @dev Contract module that helps prevent reentrant calls to a function.
 *
 * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
 * available, which can be applied to functions to make sure there are no nested
 * (reentrant) calls to them.
 *
 * Note that because there is a single `nonReentrant` guard, functions marked as
 * `nonReentrant` may not call one another. This can be worked around by making
 * those functions `private`, and then adding `external` `nonReentrant` entry
 * points to them.
 *
 * TIP: If you would like to learn more about reentrancy and alternative ways
 * to protect against it, check out our blog post
 * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
 */
abstract contract ReentrancyGuard {
    // Booleans are more expensive than uint256 or any type that takes up a full
    // word because each write operation emits an extra SLOAD to first read the
    // slot's contents, replace the bits taken up by the boolean, and then write
    // back. This is the compiler's defense against contract upgrades and
    // pointer aliasing, and it cannot be disabled.

    // The values being non-zero value makes deployment a bit more expensive,
    // but in exchange the refund on every call to nonReentrant will be lower in
    // amount. Since refunds are capped to a percentage of the total
    // transaction's gas, it is best to keep them low in cases like this one, to
    // increase the likelihood of the full refund coming into effect.
    uint256 private constant _NOT_ENTERED = 1;
    uint256 private constant _ENTERED = 2;

    uint256 private _status;

    constructor () {
        _status = _NOT_ENTERED;
    }

    /**
     * @dev Prevents a contract from calling itself, directly or indirectly.
     * Calling a `nonReentrant` function from another `nonReentrant`
     * function is not supported. It is possible to prevent this from happening
     * by making the `nonReentrant` function external, and make it call a
     * `private` function that does the actual work.
     */
    modifier nonReentrant() {
        // On the first call to nonReentrant, _notEntered will be true
        require(_status != _ENTERED, "ReentrancyGuard: reentrant call");

        // Any calls to nonReentrant after this point will fail
        _status = _ENTERED;

        _;

        // By storing the original value once again, a refund is triggered (see
        // https://eips.ethereum.org/EIPS/eip-2200)
        _status = _NOT_ENTERED;
    }
}


ReentrancyGuard

_chainId

version

DefaultReceiveVersionSet

DefaultSendVersionSet

NewLibraryVersionAdded

srcChainId

srcAddress

nonce

dstAddress

PayloadCleared

payload

reason

PayloadStored

chainId

UaForceResumeReceive

UaReceiveVersionSet

UaSendVersionSet

BLOCK_VERSION

DEFAULT_VERSION

defaultReceiveLibraryAddress

defaultReceiveVersion

defaultSendLibrary

defaultSendVersion

_dstChainId

_userApplication

_payload

_payInZRO

_adapterParams

estimateFees

nativeFee

zroFee

_srcChainId

_srcAddress

forceResumeReceive

getChainId

_version

_configType

getConfig

getInboundNonce

getOutboundNonce

getReceiveLibraryAddress

receiveLibraryAddress

getReceiveVersion

getSendLibraryAddress

sendLibraryAddress

getSendVersion

hasStoredPayload

inboundNonce

isReceivingPayload

isSendingPayload

latestVersion

libraryLookup

_newLayerZeroLibraryAddress

newVersion

outboundNonce

_dstAddress

_nonce

_gasLimit

receivePayload

retryPayload

_destination

_refundAddress

_zroPaymentAddress

send

_config

setConfig

_newDefaultReceiveVersion

setDefaultReceiveVersion

_newDefaultSendVersion

setDefaultSendVersion

_newVersion

setReceiveVersion

setSendVersion

storedPayload

payloadLength

payloadHash

uaConfigLookup

sendVersion

receiveVersion

sendLibrary

// SPDX-License-Identifier: BUSL-1.1

pragma solidity 0.7.6;

import "./interfaces/ILayerZeroReceiver.sol";
import "./interfaces/ILayerZeroEndpoint.sol";
import "./interfaces/ILayerZeroMessagingLibrary.sol";

import "@openzeppelin/contracts/access/Ownable.sol";

contract Endpoint is Ownable, ILayerZeroEndpoint {
    uint16 public immutable chainId;

    // installed libraries and reserved versions
    uint16 public constant BLOCK_VERSION = 65535;
    uint16 public constant DEFAULT_VERSION = 0;
    uint16 public latestVersion;
    mapping(uint16 => ILayerZeroMessagingLibrary) public libraryLookup; // version -> ILayerZeroEndpointLibrary

    // default send/receive libraries
    uint16 public defaultSendVersion;
    uint16 public defaultReceiveVersion;
    ILayerZeroMessagingLibrary public defaultSendLibrary;
    address public defaultReceiveLibraryAddress;

    struct LibraryConfig {
        uint16 sendVersion;
        uint16 receiveVersion;
        address receiveLibraryAddress;
        ILayerZeroMessagingLibrary sendLibrary;
    }

    struct StoredPayload {
        uint64 payloadLength;
        address dstAddress;
        bytes32 payloadHash;
    }

    // user app config = [uaAddress]
    mapping(address => LibraryConfig) public uaConfigLookup;
    // inboundNonce = [srcChainId][srcAddress].
    mapping(uint16 => mapping(bytes => uint64)) public inboundNonce;
    // outboundNonce = [dstChainId][srcAddress].
    mapping(uint16 => mapping(address => uint64)) public outboundNonce;
    // storedPayload = [srcChainId][srcAddress]
    mapping(uint16 => mapping(bytes => StoredPayload)) public storedPayload;

    // library versioning events
    event NewLibraryVersionAdded(uint16 version);
    event DefaultSendVersionSet(uint16 version);
    event DefaultReceiveVersionSet(uint16 version);
    event UaSendVersionSet(address ua, uint16 version);
    event UaReceiveVersionSet(address ua, uint16 version);
    event UaForceResumeReceive(uint16 chainId, bytes srcAddress);
    // payload events
    event PayloadCleared(uint16 srcChainId, bytes srcAddress, uint64 nonce, address dstAddress);
    event PayloadStored(uint16 srcChainId, bytes srcAddress, address dstAddress, uint64 nonce, bytes payload, bytes reason);

    constructor(uint16 _chainId) {
        chainId = _chainId;
    }

    //---------------------------------------------------------------------------
    // send and receive nonreentrant lock
    uint8 internal constant _NOT_ENTERED = 1;
    uint8 internal constant _ENTERED = 2;
    uint8 internal _send_entered_state = 1;
    uint8 internal _receive_entered_state = 1;

    modifier sendNonReentrant() {
        require(_send_entered_state == _NOT_ENTERED, "LayerZero: no send reentrancy");
        _send_entered_state = _ENTERED;
        _;
        _send_entered_state = _NOT_ENTERED;
    }
    modifier receiveNonReentrant() {
        require(_receive_entered_state == _NOT_ENTERED, "LayerZero: no receive reentrancy");
        _receive_entered_state = _ENTERED;
        _;
        _receive_entered_state = _NOT_ENTERED;
    }

    // BLOCK_VERSION is also a valid version
    modifier validVersion(uint16 _version) {
        require(_version <= latestVersion || _version == BLOCK_VERSION, "LayerZero: invalid messaging library version");
        _;
    }

    //---------------------------------------------------------------------------
    // User Application Calls - Endpoint Interface

    function send(uint16 _dstChainId, bytes calldata _destination, bytes calldata _payload, address payable _refundAddress, address _zroPaymentAddress, bytes calldata _adapterParams) external payable override sendNonReentrant {
        LibraryConfig storage uaConfig = uaConfigLookup[msg.sender];
        uint64 nonce = ++outboundNonce[_dstChainId][msg.sender];
        _getSendLibrary(uaConfig).send{value: msg.value}(msg.sender, nonce, _dstChainId, _destination, _payload, _refundAddress, _zroPaymentAddress, _adapterParams);
    }

    //---------------------------------------------------------------------------
    // authenticated Library (msg.sender) Calls to pass through Endpoint to UA (dstAddress)
    function receivePayload(uint16 _srcChainId, bytes calldata _srcAddress, address _dstAddress, uint64 _nonce, uint _gasLimit, bytes calldata _payload) external override receiveNonReentrant {
        // assert and increment the nonce. no message shuffling
        require(_nonce == ++inboundNonce[_srcChainId][_srcAddress], "LayerZero: wrong nonce");

        LibraryConfig storage uaConfig = uaConfigLookup[_dstAddress];

        // authentication to prevent cross-version message validation
        // protects against a malicious library from passing arbitrary data
        if (uaConfig.receiveVersion == DEFAULT_VERSION) {
            require(defaultReceiveLibraryAddress == msg.sender, "LayerZero: invalid default library");
        } else {
            require(uaConfig.receiveLibraryAddress == msg.sender, "LayerZero: invalid library");
        }

        // block if any message blocking
        StoredPayload storage sp = storedPayload[_srcChainId][_srcAddress];
        require(sp.payloadHash == bytes32(0), "LayerZero: in message blocking");

        try ILayerZeroReceiver(_dstAddress).lzReceive{gas: _gasLimit}(_srcChainId, _srcAddress, _nonce, _payload) {
            // success, do nothing, end of the message delivery
        } catch (bytes memory reason) {
            // revert nonce if any uncaught errors/exceptions if the ua chooses the blocking mode
            storedPayload[_srcChainId][_srcAddress] = StoredPayload(uint64(_payload.length), _dstAddress, keccak256(_payload));
            emit PayloadStored(_srcChainId, _srcAddress, _dstAddress, _nonce, _payload, reason);
        }
    }

    function retryPayload(uint16 _srcChainId, bytes calldata _srcAddress, bytes calldata _payload) external override receiveNonReentrant {
        StoredPayload storage sp = storedPayload[_srcChainId][_srcAddress];
        require(sp.payloadHash != bytes32(0), "LayerZero: no stored payload");
        require(_payload.length == sp.payloadLength && keccak256(_payload) == sp.payloadHash, "LayerZero: invalid payload");

        address dstAddress = sp.dstAddress;
        // empty the storedPayload
        sp.payloadLength = 0;
        sp.dstAddress = address(0);
        sp.payloadHash = bytes32(0);

        uint64 nonce = inboundNonce[_srcChainId][_srcAddress];

        ILayerZeroReceiver(dstAddress).lzReceive(_srcChainId, _srcAddress, nonce, _payload);
        emit PayloadCleared(_srcChainId, _srcAddress, nonce, dstAddress);
    }

    //---------------------------------------------------------------------------
    // Owner Calls, only new library version upgrade (3 steps)

    // note libraryLookup[0] = 0x0, no library implementation
    // LIBRARY UPGRADE step 1: set _newLayerZeroLibraryAddress be the new version
    function newVersion(address _newLayerZeroLibraryAddress) external onlyOwner {
        require(_newLayerZeroLibraryAddress != address(0x0), "LayerZero: new version cannot be zero address");
        require(latestVersion < 65535, "LayerZero: can not add new messaging library");
        latestVersion++;
        libraryLookup[latestVersion] = ILayerZeroMessagingLibrary(_newLayerZeroLibraryAddress);
        emit NewLibraryVersionAdded(latestVersion);
    }

    // LIBRARY UPGRADE step 2: stop sending messages from the old version
    function setDefaultSendVersion(uint16 _newDefaultSendVersion) external onlyOwner validVersion(_newDefaultSendVersion) {
        require(_newDefaultSendVersion != DEFAULT_VERSION, "LayerZero: default send version must > 0");
        defaultSendVersion = _newDefaultSendVersion;
        defaultSendLibrary = libraryLookup[defaultSendVersion];
        emit DefaultSendVersionSet(_newDefaultSendVersion);
    }

    // LIBRARY UPGRADE step 3: stop receiving messages from the old version
    function setDefaultReceiveVersion(uint16 _newDefaultReceiveVersion) external onlyOwner validVersion(_newDefaultReceiveVersion) {
        require(_newDefaultReceiveVersion != DEFAULT_VERSION, "LayerZero: default receive version must > 0");
        defaultReceiveVersion = _newDefaultReceiveVersion;
        defaultReceiveLibraryAddress = address(libraryLookup[defaultReceiveVersion]);
        emit DefaultReceiveVersionSet(_newDefaultReceiveVersion);
    }

    //---------------------------------------------------------------------------
    // User Application Calls - UA set/get Interface

    function setConfig(uint16 _version, uint16 _chainId, uint _configType, bytes calldata _config) external override validVersion(_version) {
        if (_version == DEFAULT_VERSION) {
            require(defaultSendVersion == defaultReceiveVersion, "LayerZero: can not set Config during DEFAULT migration");
            _version = defaultSendVersion;
        }
        require(_version != BLOCK_VERSION, "LayerZero: can not set config for BLOCK_VERSION");
        libraryLookup[_version].setConfig(_chainId, msg.sender, _configType, _config);
    }

    // Migration step 1: set the send version
    // Define what library the UA points too
    function setSendVersion(uint16 _newVersion) external override validVersion(_newVersion) {
        // write into config
        LibraryConfig storage uaConfig = uaConfigLookup[msg.sender];
        uaConfig.sendVersion = _newVersion;
        // the libraryLookup[BLOCK_VERSION || DEFAULT_VERSION] = 0x0
        uaConfig.sendLibrary = libraryLookup[_newVersion];
        emit UaSendVersionSet(msg.sender, _newVersion);
    }

    // Migration step 2: set the receive version
    // after all messages sent from the old version are received
    // the UA can now safely switch to the new receive version
    // it is the UA's responsibility make sure all messages from the old version are processed
    function setReceiveVersion(uint16 _newVersion) external override validVersion(_newVersion) {
        // write into config
        LibraryConfig storage uaConfig = uaConfigLookup[msg.sender];
        uaConfig.receiveVersion = _newVersion;
        // the libraryLookup[BLOCK_VERSION || DEFAULT_VERSION] = 0x0
        uaConfig.receiveLibraryAddress = address(libraryLookup[_newVersion]);
        emit UaReceiveVersionSet(msg.sender, _newVersion);
    }

    function forceResumeReceive(uint16 _srcChainId, bytes calldata _srcAddress) external override {
        StoredPayload storage sp = storedPayload[_srcChainId][_srcAddress];
        // revert if no messages are cached. safeguard malicious UA behaviour
        require(sp.payloadHash != bytes32(0), "LayerZero: no stored payload");
        require(sp.dstAddress == msg.sender, "LayerZero: invalid caller");

        // empty the storedPayload
        sp.payloadLength = 0;
        sp.dstAddress = address(0);
        sp.payloadHash = bytes32(0);

        // emit the event with the new nonce
        emit UaForceResumeReceive(_srcChainId, _srcAddress);
    }

    //---------------------------------------------------------------------------
    // view helper function

    function estimateFees(uint16 _dstChainId, address _userApplication, bytes calldata _payload, bool _payInZRO, bytes calldata _adapterParams) external view override returns (uint nativeFee, uint zroFee) {
        LibraryConfig storage uaConfig = uaConfigLookup[_userApplication];
        ILayerZeroMessagingLibrary lib = uaConfig.sendVersion == DEFAULT_VERSION ? defaultSendLibrary : uaConfig.sendLibrary;
        return lib.estimateFees(_dstChainId, _userApplication, _payload, _payInZRO, _adapterParams);
    }

    function _getSendLibrary(LibraryConfig storage uaConfig) internal view returns (ILayerZeroMessagingLibrary) {
        if (uaConfig.sendVersion == DEFAULT_VERSION) {
            // check if the in send-blocking upgrade
            require(defaultSendVersion != BLOCK_VERSION, "LayerZero: default in BLOCK_VERSION");
            return defaultSendLibrary;
        } else {
            // check if the in send-blocking upgrade
            require(uaConfig.sendVersion != BLOCK_VERSION, "LayerZero: in BLOCK_VERSION");
            return uaConfig.sendLibrary;
        }
    }

    function getSendLibraryAddress(address _userApplication) external view override returns (address sendLibraryAddress) {
        LibraryConfig storage uaConfig = uaConfigLookup[_userApplication];
        uint16 sendVersion = uaConfig.sendVersion;
        require(sendVersion != BLOCK_VERSION, "LayerZero: send version is BLOCK_VERSION");
        if (sendVersion == DEFAULT_VERSION) {
            require(defaultSendVersion != BLOCK_VERSION, "LayerZero: send version (default) is BLOCK_VERSION");
            sendLibraryAddress = address(defaultSendLibrary);
        } else {
            sendLibraryAddress = address(uaConfig.sendLibrary);
        }
    }

    function getReceiveLibraryAddress(address _userApplication) external view override returns (address receiveLibraryAddress) {
        LibraryConfig storage uaConfig = uaConfigLookup[_userApplication];
        uint16 receiveVersion = uaConfig.receiveVersion;
        require(receiveVersion != BLOCK_VERSION, "LayerZero: receive version is BLOCK_VERSION");
        if (receiveVersion == DEFAULT_VERSION) {
            require(defaultReceiveVersion != BLOCK_VERSION, "LayerZero: receive version (default) is BLOCK_VERSION");
            receiveLibraryAddress = defaultReceiveLibraryAddress;
        } else {
            receiveLibraryAddress = uaConfig.receiveLibraryAddress;
        }
    }

    function isSendingPayload() external view override returns (bool) {
        return _send_entered_state == _ENTERED;
    }

    function isReceivingPayload() external view override returns (bool) {
        return _receive_entered_state == _ENTERED;
    }

    function getInboundNonce(uint16 _srcChainId, bytes calldata _srcAddress) external view override returns (uint64) {
        return inboundNonce[_srcChainId][_srcAddress];
    }

    function getOutboundNonce(uint16 _dstChainId, address _srcAddress) external view override returns (uint64) {
        return outboundNonce[_dstChainId][_srcAddress];
    }

    function getChainId() external view override returns (uint16) {
        return chainId;
    }

    function getSendVersion(address _userApplication) external view override returns (uint16) {
        LibraryConfig storage uaConfig = uaConfigLookup[_userApplication];
        return uaConfig.sendVersion == DEFAULT_VERSION ? defaultSendVersion : uaConfig.sendVersion;
    }

    function getReceiveVersion(address _userApplication) external view override returns (uint16) {
        LibraryConfig storage uaConfig = uaConfigLookup[_userApplication];
        return uaConfig.receiveVersion == DEFAULT_VERSION ? defaultReceiveVersion : uaConfig.receiveVersion;
    }

    function getConfig(uint16 _version, uint16 _chainId, address _userApplication, uint _configType) external view override validVersion(_version) returns (bytes memory) {
        if (_version == DEFAULT_VERSION) {
            require(defaultSendVersion == defaultReceiveVersion, "LayerZero: no DEFAULT config while migration");
            _version = defaultSendVersion;
        }
        require(_version != BLOCK_VERSION, "LayerZero: can not get config for BLOCK_VERSION");
        return libraryLookup[_version].getConfig(_chainId, _userApplication, _configType);
    }

    function hasStoredPayload(uint16 _srcChainId, bytes calldata _srcAddress) external view override returns (bool) {
        StoredPayload storage sp = storedPayload[_srcChainId][_srcAddress];
        return sp.payloadHash != bytes32(0);
    }
}


Endpoint

_endpoint

endpoint

_path

increment

// SPDX-License-Identifier: BUSL-1.1

pragma solidity 0.7.6;

import "./interfaces/ILayerZeroEndpoint.sol";

contract NonceContract {
    ILayerZeroEndpoint public immutable endpoint;
    // outboundNonce = [dstChainId][remoteAddress + localAddress]
    mapping(uint16 => mapping(bytes => uint64)) public outboundNonce;

    constructor(address _endpoint) {
        endpoint = ILayerZeroEndpoint(_endpoint);
    }

    function increment(uint16 _chainId, address _ua, bytes calldata _path) external returns (uint64) {
        require(endpoint.getSendLibraryAddress(_ua) == msg.sender, "NonceContract: msg.sender is not valid sendlibrary");
        return ++outboundNonce[_chainId][_path];
    }
}


NonceContract

addr

approved

ApproveAddress

Withdraw

token

WithdrawTokens

approvedAddresses

dstConfigLookup

dstNativeAmtCap

baseGas

gasPerByte

dstPriceLookup

dstPriceRatio

dstGasPriceInWei

_outboundProofType

payloadSize

getPrice

_uln

initialize

_relayerAddress

isApproved

notifyRelayer

_approve

setApprovedAddress

_dstNativeAmtCap

_baseGas

_gasPerByte

setDstConfig

_dstPriceRatio

_dstGasPriceInWei

setDstPrice

_blockHash

_transactionProof

validateTransactionProofV1

validateTransactionProofV2

_amount

withdrawQuotedFromULN

// SPDX-License-Identifier: BUSL-1.1

pragma solidity ^0.7.6;

import "@openzeppelin/contracts/access/Ownable.sol";
import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts-upgradeable/proxy/Initializable.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "hardhat-deploy/solc_0.7/proxy/Proxied.sol";

import "./interfaces/ILayerZeroRelayer.sol";
import "./interfaces/ILayerZeroUltraLightNodeV1.sol";

contract Relayer is ILayerZeroRelayer, ReentrancyGuard, OwnableUpgradeable, Proxied {
    using SafeERC20 for IERC20;
    using SafeMath for uint;
    using SafeMath for uint128;
    using SafeMath for uint64;

    ILayerZeroUltraLightNodeV1 public uln;

    struct DstPrice {
        uint128 dstPriceRatio; // 10^10
        uint128 dstGasPriceInWei;
    }

    struct DstConfig {
        uint128 dstNativeAmtCap;
        uint64 baseGas;
        uint64 gasPerByte;
    }

    // [_chainId] => DstPriceData. change often
    mapping(uint16 => DstPrice) public dstPriceLookup;
    // [_chainId][_outboundProofType] => DstConfig. change much less often
    mapping(uint16 => mapping(uint16 => DstConfig)) public dstConfigLookup;

    mapping(address => bool) public approvedAddresses;

    event WithdrawTokens(address token, address to, uint amount);
    event Withdraw(address to, uint amount);
    event ApproveAddress(address addr, bool approved);

    // owner is always approved
    modifier onlyApproved() {
        if (owner() != msg.sender) {
            require(isApproved(msg.sender), "Relayer: not approved");
        }
        _;
    }

    function initialize(address _uln) public proxied initializer {
        __Ownable_init();
        uln = ILayerZeroUltraLightNodeV1(_uln);
        setApprovedAddress(address(this), true);
    }

    //----------------------------------------------------------------------------------
    // onlyApproved
    function validateTransactionProofV2(uint16 _srcChainId, address _dstAddress, uint _gasLimit, bytes32 _blockHash, bytes calldata _transactionProof, address payable _to) external payable onlyApproved nonReentrant {
        (bool sent, ) = _to.call{value: msg.value}("");
        require(sent, "Relayer: failed to send ether");
        uln.validateTransactionProof(_srcChainId, _dstAddress, _gasLimit, _blockHash, _transactionProof);
    }

    function validateTransactionProofV1(uint16 _srcChainId, address _dstAddress, uint _gasLimit, bytes32 _blockHash, bytes calldata _transactionProof) external onlyApproved nonReentrant {
        uln.validateTransactionProof(_srcChainId, _dstAddress, _gasLimit, _blockHash, _transactionProof);
    }

    function setDstPrice(uint16 _chainId, uint128 _dstPriceRatio, uint128 _dstGasPriceInWei) external onlyApproved {
        dstPriceLookup[_chainId] = DstPrice(_dstPriceRatio, _dstGasPriceInWei);
    }

    function setDstConfig(uint16 _chainId, uint16 _outboundProofType, uint128 _dstNativeAmtCap, uint64 _baseGas, uint64 _gasPerByte) external onlyApproved {
        dstConfigLookup[_chainId][_outboundProofType] = DstConfig(_dstNativeAmtCap, _baseGas, _gasPerByte);
    }

    // other relayer fees are withdrawn through the RelayerFee interface
    // uint8 public constant WITHDRAW_TYPE_RELAYER_QUOTED_FEES = 2;
    function withdrawQuotedFromULN(address payable _to, uint _amount) external onlyApproved {
        uln.withdrawNative(2, address(0x0), _to, _amount);
    }

    //----------------------------------------------------------------------------------
    // onlyOwner

    function setApprovedAddress(address _relayerAddress, bool _approve) public onlyOwner {
        approvedAddresses[_relayerAddress] = _approve;
        emit ApproveAddress(_relayerAddress, _approve);
    }

    //----------------------------------------------------------------------------------
    // view functions

    // txType 1
    // bytes  [2       32      ]
    // fields [txType  extraGas]
    // txType 2
    // bytes  [2       32        32            bytes[]         ]
    // fields [txType  extraGas  dstNativeAmt  dstNativeAddress]
    // User App Address is not used in this version
    function _getPrices(uint16 _dstChainId, uint16 _outboundProofType, address, bytes memory _adapterParameters) internal view returns (uint basePrice, uint pricePerByte) {
        // decoding the _adapterParameters - reverts if type 2 and there is no dstNativeAddress
        require(_adapterParameters.length == 34 || _adapterParameters.length > 66, "Relayer: wrong _adapterParameters size");
        uint16 txType;
        uint extraGas;
        assembly {
            txType := mload(add(_adapterParameters, 2))
            extraGas := mload(add(_adapterParameters, 34))
        }
        require(extraGas > 0, "Relayer: gas too low");
        require(txType == 1 || txType == 2, "Relayer: unsupported txType");

        DstPrice storage dstPrice = dstPriceLookup[_dstChainId];
        DstConfig storage dstConfig = dstConfigLookup[_dstChainId][_outboundProofType];

        uint totalRemoteToken; // = baseGas + extraGas + requiredNativeAmount
        if (txType == 2) {
            uint dstNativeAmt;
            assembly {
                dstNativeAmt := mload(add(_adapterParameters, 66))
            }
            require(dstConfig.dstNativeAmtCap >= dstNativeAmt, "Relayer: dstNativeAmt too large");
            totalRemoteToken = totalRemoteToken.add(dstNativeAmt);
        }
        // remoteGasTotal = dstGasPriceInWei * (baseGas + extraGas)
        uint remoteGasTotal = dstPrice.dstGasPriceInWei.mul(dstConfig.baseGas.add(extraGas));

        totalRemoteToken = totalRemoteToken.add(remoteGasTotal);

        // tokenConversionRate = dstPrice / localPrice
        // basePrice = totalRemoteToken * tokenConversionRate
        basePrice = totalRemoteToken.mul(dstPrice.dstPriceRatio).div(10**10);

        // pricePerByte = (dstGasPriceInWei * gasPerBytes) * tokenConversionRate
        pricePerByte = dstPrice.dstGasPriceInWei.mul(dstConfig.gasPerByte).mul(dstPrice.dstPriceRatio).div(10**10);
    }

    function notifyRelayer(uint16 _dstChainId, uint16 _outboundProofType, bytes calldata _adapterParams) external override {
        //do nothing
    }

    function getPrice(uint16 _dstChainId, uint16 _outboundProofType, address _userApplication, uint payloadSize, bytes calldata _adapterParams) external view override returns (uint) {
        (uint basePrice, uint pricePerByte) = _getPrices(_dstChainId, _outboundProofType, _userApplication, _adapterParams);
        return basePrice.add(payloadSize.mul(pricePerByte));
    }

    function isApproved(address _relayerAddress) public view override returns (bool) {
        return approvedAddresses[_relayerAddress];
    }
}


Relayer

totalFee

AssignJob

outboundProofType

SetDstConfig

SetDstPrice

quantity

ValueTransferFailed

_payloadSize

assignJob

getFee

paused

_paused

setPause

_stargateAddress

setStargateAddress

stargateBridgeAddress

_data

withdrawFee

// SPDX-License-Identifier: BUSL-1.1

pragma solidity ^0.7.6;

import "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import "@openzeppelin/contracts/token/ERC20/SafeERC20.sol";
import "@openzeppelin/contracts/utils/ReentrancyGuard.sol";
import "@openzeppelin/contracts/math/SafeMath.sol";
import "@openzeppelin/contracts-upgradeable/access/OwnableUpgradeable.sol";
import "hardhat-deploy/solc_0.7/proxy/Proxied.sol";

import "./interfaces/ILayerZeroRelayerV2.sol";
import "./interfaces/ILayerZeroUltraLightNodeV2.sol";

contract RelayerV2 is ReentrancyGuard, OwnableUpgradeable, Proxied, ILayerZeroRelayerV2 {
    using SafeERC20 for IERC20;
    using SafeMath for uint;
    using SafeMath for uint128;
    using SafeMath for uint64;

    ILayerZeroUltraLightNodeV2 public uln;
    address public stargateBridgeAddress;

    struct DstPrice {
        uint128 dstPriceRatio; // 10^10
        uint128 dstGasPriceInWei;
    }

    struct DstConfig {
        uint128 dstNativeAmtCap;
        uint64 baseGas;
        uint64 gasPerByte;
    }

    // [_chainId] => DstPriceData. change often
    mapping(uint16 => DstPrice) public dstPriceLookup;
    // [_chainId][_outboundProofType] => DstConfig. change much less often
    mapping(uint16 => mapping(uint16 => DstConfig)) public dstConfigLookup;
    mapping(address => bool) public approvedAddresses;

    event Withdraw(address to, uint amount);
    event ApproveAddress(address addr, bool approved);
    event AssignJob(uint totalFee);
    event ValueTransferFailed(address indexed to, uint indexed quantity);
    event SetDstPrice(uint16 chainId, uint128 dstPriceRatio, uint128 dstGasPriceInWei);
    event SetDstConfig(uint16 chainId, uint16 outboundProofType, uint128 dstNativeAmtCap, uint64 baseGas, uint64 gasPerByte);

    // new pauseable relayer
    bool public paused;

    // owner is always approved
    modifier onlyApproved() {
        if (owner() != msg.sender) {
            require(isApproved(msg.sender), "Relayer: not approved");
        }
        _;
    }

    function initialize(address _uln) public proxied initializer {
        __Ownable_init();
        uln = ILayerZeroUltraLightNodeV2(_uln);
        setApprovedAddress(address(this), true);
    }

    //----------------------------------------------------------------------------------
    // onlyApproved

    function setDstPrice(uint16 _chainId, uint128 _dstPriceRatio, uint128 _dstGasPriceInWei) external onlyApproved {
        dstPriceLookup[_chainId] = DstPrice(_dstPriceRatio, _dstGasPriceInWei);
        emit SetDstPrice(_chainId, _dstPriceRatio, _dstGasPriceInWei);
    }

    function setDstConfig(uint16 _chainId, uint16 _outboundProofType, uint128 _dstNativeAmtCap, uint64 _baseGas, uint64 _gasPerByte) external onlyApproved {
        dstConfigLookup[_chainId][_outboundProofType] = DstConfig(_dstNativeAmtCap, _baseGas, _gasPerByte);
        emit SetDstConfig(_chainId, _outboundProofType, _dstNativeAmtCap, _baseGas, _gasPerByte);
    }

    function setStargateAddress(address _stargateAddress) external onlyApproved {
        stargateBridgeAddress = _stargateAddress;
    }

    //----------------------------------------------------------------------------------
    // onlyOwner

    function setApprovedAddress(address _relayerAddress, bool _approve) public onlyOwner {
        approvedAddresses[_relayerAddress] = _approve;
        emit ApproveAddress(_relayerAddress, _approve);
    }

    function setPause(bool _paused) public onlyOwner {
        paused = _paused;
    }

    // txType 1
    // bytes  [2       32      ]
    // fields [txType  extraGas]
    // txType 2
    // bytes  [2       32        32            bytes[]         ]
    // fields [txType  extraGas  dstNativeAmt  dstNativeAddress]
    // User App Address is not used in this version
    function _getPrices(uint16 _dstChainId, uint16 _outboundProofType, address, bytes memory _adapterParameters) internal view returns (uint basePrice, uint pricePerByte) {
        require(!paused, "Admin: paused");
        // decoding the _adapterParameters - reverts if type 2 and there is no dstNativeAddress
        require(_adapterParameters.length == 34 || _adapterParameters.length > 66, "Relayer: wrong _adapterParameters size");
        uint16 txType;
        uint extraGas;
        assembly {
            txType := mload(add(_adapterParameters, 2))
            extraGas := mload(add(_adapterParameters, 34))
        }
        require(extraGas > 0, "Relayer: gas too low");
        require(txType == 1 || txType == 2, "Relayer: unsupported txType");

        DstPrice storage dstPrice = dstPriceLookup[_dstChainId];
        DstConfig storage dstConfig = dstConfigLookup[_dstChainId][_outboundProofType];

        uint totalRemoteToken; // = baseGas + extraGas + requiredNativeAmount
        if (txType == 2) {
            uint dstNativeAmt;
            assembly {
                dstNativeAmt := mload(add(_adapterParameters, 66))
            }
            require(dstConfig.dstNativeAmtCap >= dstNativeAmt, "Relayer: dstNativeAmt too large");
            totalRemoteToken = totalRemoteToken.add(dstNativeAmt);
        }
        // remoteGasTotal = dstGasPriceInWei * (baseGas + extraGas)
        uint remoteGasTotal = dstPrice.dstGasPriceInWei.mul(dstConfig.baseGas.add(extraGas));

        totalRemoteToken = totalRemoteToken.add(remoteGasTotal);

        // tokenConversionRate = dstPrice / localPrice
        // basePrice = totalRemoteToken * tokenConversionRate
        basePrice = totalRemoteToken.mul(dstPrice.dstPriceRatio).div(10**10);

        // pricePerByte = (dstGasPriceInWei * gasPerBytes) * tokenConversionRate
        pricePerByte = dstPrice.dstGasPriceInWei.mul(dstConfig.gasPerByte).mul(dstPrice.dstPriceRatio).div(10**10);
    }

    function getFee(uint16 _dstChainId, uint16 _outboundProofType, address _userApplication, uint _payloadSize, bytes calldata _adapterParams) external view override returns (uint) {
        require(_payloadSize <= 10000, "Relayer: _payloadSize tooooo big");
        (uint basePrice, uint pricePerByte) = _getPrices(_dstChainId, _outboundProofType, _userApplication, _adapterParams);
        return basePrice.add(_payloadSize.mul(pricePerByte));
    }

    function isApproved(address _relayerAddress) public view returns (bool) {
        return approvedAddresses[_relayerAddress];
    }

    function assignJob(uint16 _dstChainId, uint16 _outboundProofType, address _userApplication, uint _payloadSize, bytes calldata _adapterParams) external override returns (uint) {
        require(msg.sender == address(uln), "Relayer: invalid uln");
        require(_payloadSize <= 10000, "Relayer: _payloadSize tooooo big");
        (uint basePrice, uint pricePerByte) = _getPrices(_dstChainId, _outboundProofType, _userApplication, _adapterParams);
        uint totalFee = basePrice.add(_payloadSize.mul(pricePerByte));
        emit AssignJob(totalFee);
        return totalFee;
    }

    function withdrawFee(address payable _to, uint _amount) external override onlyApproved {
        uint totalFee = uln.accruedNativeFee(address(this));
        require(_amount <= totalFee, "Relayer: not enough fee for withdrawal");
        uln.withdrawNative(_to, _amount);
    }

    function validateTransactionProofV2(uint16 _srcChainId, address _dstAddress, uint _gasLimit, bytes32 _blockHash, bytes32 _data, bytes calldata _transactionProof, address payable _to) external payable onlyApproved nonReentrant {
        (bool sent, ) = _to.call{value: msg.value}("");
        //require(sent, "Relayer: failed to send ether");
        if (!sent) {
            emit ValueTransferFailed(_to, msg.value);
        }
        uln.validateTransactionProof(_srcChainId, _dstAddress, _gasLimit, _blockHash, _data, _transactionProof);
    }

    function validateTransactionProofV1(uint16 _srcChainId, address _dstAddress, uint _gasLimit, bytes32 _blockHash, bytes32 _data, bytes calldata _transactionProof) external onlyApproved nonReentrant {
        uln.validateTransactionProof(_srcChainId, _dstAddress, _gasLimit, _blockHash, _data, _transactionProof);
    }
}


RelayerV2

LayerZero is an omnichain interoperability protocol designed for lightweight message passing across chains. LayerZero provides authentic and guaranteed message delivery with configurable trustlessness.