Contract Source Code:
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
/*
* @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;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
import "../GSN/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.
*/
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 initialOwner) {
_owner = initialOwner;
emit OwnershipTransferred(address(0), initialOwner);
}
/**
* @dev Returns the address of the current owner.
*/
function owner() public view 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;
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
/**
* @dev This abstract contract provides a fallback function that delegates all calls to another contract using the EVM
* instruction `delegatecall`. We refer to the second contract as the _implementation_ behind the proxy, and it has to
* be specified by overriding the virtual {_implementation} function.
*
* Additionally, delegation to the implementation can be triggered manually through the {_fallback} function, or to a
* different contract through the {_delegate} function.
*
* The success and return data of the delegated call will be returned back to the caller of the proxy.
*/
abstract contract Proxy {
/**
* @dev Delegates the current call to `implementation`.
*
* This function does not return to its internall call site, it will return directly to the external caller.
*/
function _delegate(address implementation) internal {
// solhint-disable-next-line no-inline-assembly
assembly {
// Copy msg.data. We take full control of memory in this inline assembly
// block because it will not return to Solidity code. We overwrite the
// Solidity scratch pad at memory position 0.
calldatacopy(0, 0, calldatasize())
// Call the implementation.
// out and outsize are 0 because we don't know the size yet.
let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
// Copy the returned data.
returndatacopy(0, 0, returndatasize())
switch result
// delegatecall returns 0 on error.
case 0 { revert(0, returndatasize()) }
default { return(0, returndatasize()) }
}
}
/**
* @dev This is a virtual function that should be overriden so it returns the address to which the fallback function
* and {_fallback} should delegate.
*/
function _implementation() internal virtual view returns (address);
/**
* @dev Delegates the current call to the address returned by `_implementation()`.
*
* This function does not return to its internall call site, it will return directly to the external caller.
*/
function _fallback() internal {
_beforeFallback();
_delegate(_implementation());
}
/**
* @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if no other
* function in the contract matches the call data.
*/
fallback () payable external {
_fallback();
}
/**
* @dev Fallback function that delegates calls to the address returned by `_implementation()`. Will run if call data
* is empty.
*/
receive () payable external {
_fallback();
}
/**
* @dev Hook that is called before falling back to the implementation. Can happen as part of a manual `_fallback`
* call, or as part of the Solidity `fallback` or `receive` functions.
*
* If overriden should call `super._beforeFallback()`.
*/
function _beforeFallback() internal virtual {
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
import "../access/Ownable.sol";
import "./TransparentUpgradeableProxy.sol";
/**
* @dev This is an auxiliary contract meant to be assigned as the admin of a {TransparentUpgradeableProxy}. For an
* explanation of why you would want to use this see the documentation for {TransparentUpgradeableProxy}.
*/
contract ProxyAdmin is Ownable {
constructor(address owner) Ownable(owner) {}
/**
* @dev Returns the current implementation of `proxy`.
*
* Requirements:
*
* - This contract must be the admin of `proxy`.
*/
function getProxyImplementation(TransparentUpgradeableProxy proxy) public view returns (address) {
// We need to manually run the static call since the getter cannot be flagged as view
// bytes4(keccak256("implementation()")) == 0x5c60da1b
(bool success, bytes memory returndata) = address(proxy).staticcall(hex"5c60da1b");
require(success);
return abi.decode(returndata, (address));
}
/**
* @dev Returns the current admin of `proxy`.
*
* Requirements:
*
* - This contract must be the admin of `proxy`.
*/
function getProxyAdmin(TransparentUpgradeableProxy proxy) public view returns (address) {
// We need to manually run the static call since the getter cannot be flagged as view
// bytes4(keccak256("admin()")) == 0xf851a440
(bool success, bytes memory returndata) = address(proxy).staticcall(hex"f851a440");
require(success);
return abi.decode(returndata, (address));
}
/**
* @dev Changes the admin of `proxy` to `newAdmin`.
*
* Requirements:
*
* - This contract must be the current admin of `proxy`.
*/
function changeProxyAdmin(TransparentUpgradeableProxy proxy, address newAdmin) public onlyOwner {
proxy.changeAdmin(newAdmin);
}
/**
* @dev Upgrades `proxy` to `implementation`. See {TransparentUpgradeableProxy-upgradeTo}.
*
* Requirements:
*
* - This contract must be the admin of `proxy`.
*/
function upgrade(TransparentUpgradeableProxy proxy, address implementation) public onlyOwner {
proxy.upgradeTo(implementation);
}
/**
* @dev Upgrades `proxy` to `implementation` and calls a function on the new implementation. See
* {TransparentUpgradeableProxy-upgradeToAndCall}.
*
* Requirements:
*
* - This contract must be the admin of `proxy`.
*/
function upgradeAndCall(TransparentUpgradeableProxy proxy, address implementation, bytes memory data) public payable onlyOwner {
proxy.upgradeToAndCall{value: msg.value}(implementation, data);
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
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 inerface 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 initialLogic, address initialAdmin, bytes memory _data) payable UpgradeableProxy(initialLogic, _data) {
assert(_ADMIN_SLOT == bytes32(uint256(keccak256("eip1967.proxy.admin")) - 1));
_setAdmin(initialAdmin);
}
/**
* @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) {
return _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) {
return _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 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 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 ifAdmin {
_upgradeTo(newImplementation);
// solhint-disable-next-line avoid-low-level-calls
(bool success,) = newImplementation.delegatecall(data);
require(success);
}
/**
* @dev Returns the current admin.
*/
function _admin() internal view 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 override virtual {
require(msg.sender != _admin(), "TransparentUpgradeableProxy: admin cannot fallback to proxy target");
super._beforeFallback();
}
}
// SPDX-License-Identifier: MIT
pragma solidity ^0.7.0;
import "./Proxy.sol";
import "../utils/Address.sol";
/**
* @dev This contract implements an upgradeable proxy. It is upgradeable because calls are delegated to an
* implementation address that can be changed. This address is stored in storage in the location specified by
* https://eips.ethereum.org/EIPS/eip-1967[EIP1967], so that it doesn't conflict with the storage layout of the
* implementation behind the proxy.
*
* Upgradeability is only provided internally through {_upgradeTo}. For an externally upgradeable proxy see
* {TransparentUpgradeableProxy}.
*/
contract UpgradeableProxy is Proxy {
/**
* @dev Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
*
* If `_data` is nonempty, it's used as data in a delegate call to `_logic`. This will typically be an encoded
* function call, and allows initializating the storage of the proxy like a Solidity constructor.
*/
constructor(address _logic, bytes memory _data) payable {
assert(_IMPLEMENTATION_SLOT == bytes32(uint256(keccak256("eip1967.proxy.implementation")) - 1));
_setImplementation(_logic);
if(_data.length > 0) {
// solhint-disable-next-line avoid-low-level-calls
(bool success,) = _logic.delegatecall(_data);
require(success);
}
}
/**
* @dev Emitted when the implementation is upgraded.
*/
event Upgraded(address indexed implementation);
/**
* @dev Storage slot with the address of the current implementation.
* This is the keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1, and is
* validated in the constructor.
*/
bytes32 private constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
/**
* @dev Returns the current implementation address.
*/
function _implementation() internal override view returns (address impl) {
bytes32 slot = _IMPLEMENTATION_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
impl := sload(slot)
}
}
/**
* @dev Upgrades the proxy to a new implementation.
*
* Emits an {Upgraded} event.
*/
function _upgradeTo(address newImplementation) internal {
_setImplementation(newImplementation);
emit Upgraded(newImplementation);
}
/**
* @dev Stores a new address in the EIP1967 implementation slot.
*/
function _setImplementation(address newImplementation) private {
require(Address.isContract(newImplementation), "UpgradeableProxy: new implementation is not a contract");
bytes32 slot = _IMPLEMENTATION_SLOT;
// solhint-disable-next-line no-inline-assembly
assembly {
sstore(slot, newImplementation)
}
}
}
// 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) {
// According to EIP-1052, 0x0 is the value returned for not-yet created accounts
// and 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470 is returned
// for accounts without code, i.e. `keccak256('')`
bytes32 codehash;
bytes32 accountHash = 0xc5d2460186f7233c927e7db2dcc703c0e500b653ca82273b7bfad8045d85a470;
// solhint-disable-next-line no-inline-assembly
assembly { codehash := extcodehash(account) }
return (codehash != accountHash && codehash != 0x0);
}
/**
* @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");
return _functionCallWithValue(target, data, value, errorMessage);
}
function _functionCallWithValue(address target, bytes memory data, uint256 weiValue, string memory errorMessage) private returns (bytes memory) {
require(isContract(target), "Address: call to non-contract");
// solhint-disable-next-line avoid-low-level-calls
(bool success, bytes memory returndata) = target.call{ value: weiValue }(data);
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);
}
}
}
}
