Contract Source Code:

// SPDX-License-Identifier: MIT OR Apache-2.0
pragma solidity >=0.8.0;

// ============ Internal Imports ============
import {IGasOracle} from "../../interfaces/IGasOracle.sol";

// ============ External Imports ============
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";

/**
 * @notice A gas oracle that uses data stored within the contract.
 * @dev This contract is intended to be owned by an address that will
 * update the stored remote gas data.
 */
contract StorageGasOracle is IGasOracle, Ownable {
    // ============ Public Storage ============

    /// @notice Keyed by remote domain, gas data on that remote domain.
    mapping(uint32 => IGasOracle.RemoteGasData) public remoteGasData;

    // ============ Events ============

    /**
     * @notice Emitted when an entry in `remoteGasData` is set.
     * @param remoteDomain The remote domain in which the gas data was set for.
     * @param tokenExchangeRate The exchange rate of the remote native token quoted in the local native token.
     * @param gasPrice The gas price on the remote chain.
     */
    event RemoteGasDataSet(
        uint32 indexed remoteDomain,
        uint128 tokenExchangeRate,
        uint128 gasPrice
    );

    struct RemoteGasDataConfig {
        uint32 remoteDomain;
        uint128 tokenExchangeRate;
        uint128 gasPrice;
    }

    // ============ External Functions ============

    /**
     * @notice Returns the stored `remoteGasData` for the `_destinationDomain`.
     * @param _destinationDomain The destination domain.
     * @return tokenExchangeRate The exchange rate of the remote native token quoted in the local native token.
     * @return gasPrice The gas price on the remote chain.
     */
    function getExchangeRateAndGasPrice(
        uint32 _destinationDomain
    )
        external
        view
        override
        returns (uint128 tokenExchangeRate, uint128 gasPrice)
    {
        // Intentionally allow unset / zero values
        IGasOracle.RemoteGasData memory _data = remoteGasData[
            _destinationDomain
        ];
        return (_data.tokenExchangeRate, _data.gasPrice);
    }

    /**
     * @notice Sets the remote gas data for many remotes at a time.
     * @param _configs The configs to use when setting the remote gas data.
     */
    function setRemoteGasDataConfigs(
        RemoteGasDataConfig[] calldata _configs
    ) external onlyOwner {
        uint256 _len = _configs.length;
        for (uint256 i = 0; i < _len; i++) {
            _setRemoteGasData(_configs[i]);
        }
    }

    /**
     * @notice Sets the remote gas data using the values in `_config`.
     * @param _config The config to use when setting the remote gas data.
     */
    function setRemoteGasData(
        RemoteGasDataConfig calldata _config
    ) external onlyOwner {
        _setRemoteGasData(_config);
    }

    // ============ Internal functions ============

    /**
     * @notice Sets the remote gas data using the values in `_config`.
     * @param _config The config to use when setting the remote gas data.
     */
    function _setRemoteGasData(RemoteGasDataConfig calldata _config) internal {
        remoteGasData[_config.remoteDomain] = IGasOracle.RemoteGasData({
            tokenExchangeRate: _config.tokenExchangeRate,
            gasPrice: _config.gasPrice
        });

        emit RemoteGasDataSet(
            _config.remoteDomain,
            _config.tokenExchangeRate,
            _config.gasPrice
        );
    }
}

// SPDX-License-Identifier: MIT OR Apache-2.0
pragma solidity >=0.8.0;

interface IGasOracle {
    struct RemoteGasData {
        // The exchange rate of the remote native token quoted in the local native token.
        // Scaled with 10 decimals, i.e. 1e10 is "one".
        uint128 tokenExchangeRate;
        uint128 gasPrice;
    }

    function getExchangeRateAndGasPrice(
        uint32 _destinationDomain
    ) external view returns (uint128 tokenExchangeRate, uint128 gasPrice);
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts (last updated v4.9.0) (access/Ownable.sol)

pragma solidity ^0.8.0;

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() {
        _transferOwnership(_msgSender());
    }

    /**
     * @dev Throws if called by any account other than the owner.
     */
    modifier onlyOwner() {
        _checkOwner();
        _;
    }

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

    /**
     * @dev Throws if the sender is not the owner.
     */
    function _checkOwner() internal view virtual {
        require(owner() == _msgSender(), "Ownable: caller is not the owner");
    }

    /**
     * @dev Leaves the contract without owner. It will not be possible to call
     * `onlyOwner` functions. Can only be called by the current owner.
     *
     * NOTE: Renouncing ownership will leave the contract without an owner,
     * thereby disabling any functionality that is only available to the owner.
     */
    function renounceOwnership() public virtual onlyOwner {
        _transferOwnership(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");
        _transferOwnership(newOwner);
    }

    /**
     * @dev Transfers ownership of the contract to a new account (`newOwner`).
     * Internal function without access restriction.
     */
    function _transferOwnership(address newOwner) internal virtual {
        address oldOwner = _owner;
        _owner = newOwner;
        emit OwnershipTransferred(oldOwner, newOwner);
    }
}

// SPDX-License-Identifier: MIT
// OpenZeppelin Contracts v4.4.1 (utils/Context.sol)

pragma solidity ^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 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) {
        return msg.sender;
    }

    function _msgData() internal view virtual returns (bytes calldata) {
        return msg.data;
    }
}