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TransparentUpgradeableProxy.sol
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TransparentUpgradeableProxy.sol
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// SPDX-License-Identifier: MIT
pragma solidity >=0.6.0 <0.8.0;
import "./UpgradeableProxy.sol";
/**
* @dev This contract implements a proxy that is upgradeable by an admin.
*
* To avoid https://medium.com/nomic-labs-blog/malicious-backdoors-in-ethereum-proxies-62629adf3357[proxy selector
* clashing], which can potentially be used in an attack, this contract uses the
* https://blog.openzeppelin.com/the-transparent-proxy-pattern/[transparent proxy pattern]. This pattern implies two
* things that go hand in hand:
*
* 1. If any account other than the admin calls the proxy, the call will be forwarded to the implementation, even if
* that call matches one of the admin functions exposed by the proxy itself.
* 2. If the admin calls the proxy, it can access the admin functions, but its calls will never be forwarded to the
* implementation. If the admin tries to call a function on the implementation it will fail with an error that says
* "admin cannot fallback to proxy target".
*
* These properties mean that the admin account can only be used for admin actions like upgrading the proxy or changing
* the admin, so it's best if it's a dedicated account that is not used for anything else. This will avoid headaches due
* to sudden errors when trying to call a function from the proxy implementation.
*
* Our recommendation is for the dedicated account to be an instance of the {ProxyAdmin} contract. If set up this way,
* you should think of the `ProxyAdmin` instance as the real administrative interface of your proxy.
*/
contract TransparentUpgradeableProxy is UpgradeableProxy {
/**
* @dev Initializes an upgradeable proxy managed by `_admin`, backed by the implementation at `_logic`, and
* optionally initialized with `_data` as explained in {UpgradeableProxy-constructor}.
*/
constructor(address _logic, address admin_, bytes memory _data) public payable UpgradeableProxy(_logic, _data) {
assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
_setAdmin(admin_);
}
/**
* @dev Emitted when the admin account has changed.
*/
event AdminChanged(address previousAdmin, address newAdmin);
/**
* @dev Storage slot with the admin of the contract.
* This is the keccak-256 hash of "eip1967.proxy.admin" subtracted by 1, and is
* validated in the constructor.
*/
bytes32 private constant _ADMIN_SLOT = 0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103;
/**
* @dev Modifier used internally that will delegate the call to the implementation unless the sender is the admin.
*/
modifier ifAdmin() {
if (msg.sender == _admin()) {
_;
} else {
_fallback();
}
}
/**
* @dev Returns the current admin.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyAdmin}.
*
* TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
* https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
* `0xb53127684a568b3173ae13b9f8a6016e243e63b6e8ee1178d6a717850b5d6103`
*/
function admin() external ifAdmin returns (address admin_) {
admin_ = _admin();
}
/**
* @dev Returns the current implementation.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-getProxyImplementation}.
*
* TIP: To get this value clients can read directly from the storage slot shown below (specified by EIP1967) using the
* https://eth.wiki/json-rpc/API#eth_getstorageat[`eth_getStorageAt`] RPC call.
* `0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc`
*/
function implementation() external ifAdmin returns (address implementation_) {
implementation_ = _implementation();
}
/**
* @dev Changes the admin of the proxy.
*
* Emits an {AdminChanged} event.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-changeProxyAdmin}.
*/
function changeAdmin(address newAdmin) external virtual ifAdmin {
require(newAdmin != address(0), "TransparentUpgradeableProxy: new admin is the zero address");
emit AdminChanged(_admin(), newAdmin);
_setAdmin(newAdmin);
}
/**
* @dev Upgrade the implementation of the proxy.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-upgrade}.
*/
function upgradeTo(address newImplementation) external virtual ifAdmin {
_upgradeTo(newImplementation);
}
/**
* @dev Upgrade the implementation of the proxy, and then call a function from the new implementation as specified
* by `data`, which should be an encoded function call. This is useful to initialize new storage variables in the
* proxied contract.
*
* NOTE: Only the admin can call this function. See {ProxyAdmin-upgradeAndCall}.
*/
function upgradeToAndCall(address newImplementation, bytes calldata data) external payable virtual ifAdmin {
_upgradeTo(newImplementation);
Address.functionDelegateCall(newImplementation, data);
}
/**
* @dev Returns the current admin.
*/
function _admin() internal view virtual returns (address adm) {
bytes32 slot = _ADMIN_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
adm := sload(slot)
}
}
/**
* @dev Stores a new address in the EIP1967 admin slot.
*/
function _setAdmin(address newAdmin) private {
bytes32 slot = _ADMIN_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
sstore(slot, newAdmin)
}
}
/**
* @dev Makes sure the admin cannot access the fallback function. See {Proxy-_beforeFallback}.
*/
function _beforeFallback() internal virtual override {
require(msg.sender != _admin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
super._beforeFallback();
}
}