EIP173Proxy.sol

// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;

import "./Proxy.sol";

interface ERC165 {
    function supportsInterface(bytes4 id) external view returns (bool);
}

///@notice Proxy implementing EIP173 for ownership management
contract EIP173Proxy is Proxy {
    // ////////////////////////// EVENTS ///////////////////////////////////////////////////////////////////////

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

    // /////////////////////// CONSTRUCTOR //////////////////////////////////////////////////////////////////////

    constructor(
        address implementationAddress,
        address ownerAddress,
        bytes memory data
    ) payable {
        _setImplementation(implementationAddress, data);
        _setOwner(ownerAddress);
    }

    // ///////////////////// EXTERNAL ///////////////////////////////////////////////////////////////////////////

    function owner() external view returns (address) {
        return _owner();
    }

    function supportsInterface(bytes4 id) external view returns (bool) {
        if (id == 0x01ffc9a7 || id == 0x7f5828d0) {
            return true;
        }
        if (id == 0xFFFFFFFF) {
            return false;
        }

        ERC165 implementation;
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            implementation := sload(0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc)
        }

        // Technically this is not standard compliant as ERC-165 require 30,000 gas which that call cannot ensure
        // because it is itself inside `supportsInterface` that might only get 30,000 gas.
        // In practise this is unlikely to be an issue.
        try implementation.supportsInterface(id) returns (bool support) {
            return support;
        } catch {
            return false;
        }
    }

    function transferOwnership(address newOwner) external onlyOwner {
        _setOwner(newOwner);
    }

    function upgradeTo(address newImplementation) external onlyOwner {
        _setImplementation(newImplementation, "");
    }

    function upgradeToAndCall(address newImplementation, bytes calldata data) external payable onlyOwner {
        _setImplementation(newImplementation, data);
    }

    // /////////////////////// MODIFIERS ////////////////////////////////////////////////////////////////////////

    modifier onlyOwner() {
        require(msg.sender == _owner(), "NOT_AUTHORIZED");
        _;
    }

    // ///////////////////////// INTERNAL //////////////////////////////////////////////////////////////////////

    function _owner() internal view returns (address adminAddress) {
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            adminAddress := sload(0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103)
        }
    }

    function _setOwner(address newOwner) internal {
        address previousOwner = _owner();
        // solhint-disable-next-line security/no-inline-assembly
        assembly {
            sstore(0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103, newOwner)
        }
        emit OwnershipTransferred(previousOwner, newOwner);
    }
}