Contract Address Details

0x840bafDC40D88F54Db41327fe1C85241f9151243

Contract Name
WitnetProxy
Creator
0x73f1ba–3889e7 at 0x2a6841–ddd12c
Implementation
0x0000000000000000000000000000000000000000
Balance
0 ELA
Tokens
Fetching tokens...
Transactions
Transfers
Gas Used
Last Balance Update
24763657
Contract name:
WitnetProxy




Optimization enabled
true
Compiler version
v0.8.17+commit.8df45f5f




Optimization runs
200
EVM Version
default




Verified at
2023-04-26 12:59:07.771119Z

Contract source code

// SPDX-License-Identifier: MIT
pragma solidity >=0.7.0 <0.9.0;
pragma experimental ABIEncoderV2;
/**
* @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
* ====
*
* [IMPORTANT]
* ====
* You shouldn't rely on `isContract` to protect against flash loan attacks!
*
* Preventing calls from contracts is highly discouraged. It breaks composability, breaks support for smart wallets
* like Gnosis Safe, and does not provide security since it can be circumvented by calling from a contract
* constructor.
* ====
*/
function isContract(address account) internal view returns (bool) {
// This method relies on extcodesize/address.code.length, which returns 0
// for contracts in construction, since the code is only stored at the end
// of the constructor execution.
return account.code.length > 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");
(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 functionCallWithValue(target, data, 0, "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");
(bool success, bytes memory returndata) = target.call{value: value}(data);
return verifyCallResultFromTarget(target, 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) {
(bool success, bytes memory returndata) = target.staticcall(data);
return verifyCallResultFromTarget(target, success, returndata, errorMessage);
}
/**
* @dev Tool to verify that a low level call to smart-contract was successful, and revert (either by bubbling
* the revert reason or using the provided one) in case of unsuccessful call or if target was not a contract.
*
* _Available since v4.8._
*/
function verifyCallResultFromTarget(
address target,
bool success,
bytes memory returndata,
string memory errorMessage
) internal view returns (bytes memory) {
if (success) {
if (returndata.length == 0) {
// only check isContract if the call was successful and the return data is empty
// otherwise we already know that it was a contract
require(isContract(target), "Address: call to non-contract");
}
return returndata;
} else {
_revert(returndata, errorMessage);
}
}
/**
* @dev Tool to verify that a low level call was successful, and revert if it wasn't, either by bubbling the
* revert reason or using the provided one.
*
* _Available since v4.3._
*/
function verifyCallResult(
bool success,
bytes memory returndata,
string memory errorMessage
) internal pure returns (bytes memory) {
if (success) {
return returndata;
} else {
_revert(returndata, errorMessage);
}
}
function _revert(bytes memory returndata, string memory errorMessage) private pure {
// 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
/// @solidity memory-safe-assembly
assembly {
let returndata_size := mload(returndata)
revert(add(32, returndata), returndata_size)
}
} else {
revert(errorMessage);
}
}
}
/**
* @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 proxied contracts do not make use of 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.
*
* The initialization functions use a version number. Once a version number is used, it is consumed and cannot be
* reused. This mechanism prevents re-execution of each "step" but allows the creation of new initialization steps in
* case an upgrade adds a module that needs to be initialized.
*
* For example:
*
* [.hljs-theme-light.nopadding]
* ```
* contract MyToken is ERC20Upgradeable {
* function initialize() initializer public {
* __ERC20_init("MyToken", "MTK");
* }
* }
* contract MyTokenV2 is MyToken, ERC20PermitUpgradeable {
* function initializeV2() reinitializer(2) public {
* __ERC20Permit_init("MyToken");
* }
* }
* ```
*
* 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 {ERC1967Proxy-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.
*
* [CAUTION]
* ====
* Avoid leaving a contract uninitialized.
*
* An uninitialized contract can be taken over by an attacker. This applies to both a proxy and its implementation
* contract, which may impact the proxy. To prevent the implementation contract from being used, you should invoke
* the {_disableInitializers} function in the constructor to automatically lock it when it is deployed:
*
* [.hljs-theme-light.nopadding]
* ```
* /// @custom:oz-upgrades-unsafe-allow constructor
* constructor() {
* _disableInitializers();
* }
* ```
* ====
*/
abstract contract Initializable {
/**
* @dev Indicates that the contract has been initialized.
* @custom:oz-retyped-from bool
*/
uint8 private _initialized;
/**
* @dev Indicates that the contract is in the process of being initialized.
*/
bool private _initializing;
/**
* @dev Triggered when the contract has been initialized or reinitialized.
*/
event Initialized(uint8 version);
/**
* @dev A modifier that defines a protected initializer function that can be invoked at most once. In its scope,
* `onlyInitializing` functions can be used to initialize parent contracts.
*
* Similar to `reinitializer(1)`, except that functions marked with `initializer` can be nested in the context of a
* constructor.
*
* Emits an {Initialized} event.
*/
modifier initializer() {
bool isTopLevelCall = !_initializing;
require(
(isTopLevelCall && _initialized < 1) || (!AddressUpgradeable.isContract(address(this)) && _initialized == 1),
"Initializable: contract is already initialized"
);
_initialized = 1;
if (isTopLevelCall) {
_initializing = true;
}
_;
if (isTopLevelCall) {
_initializing = false;
emit Initialized(1);
}
}
/**
* @dev A modifier that defines a protected reinitializer function that can be invoked at most once, and only if the
* contract hasn't been initialized to a greater version before. In its scope, `onlyInitializing` functions can be
* used to initialize parent contracts.
*
* A reinitializer may be used after the original initialization step. This is essential to configure modules that
* are added through upgrades and that require initialization.
*
* When `version` is 1, this modifier is similar to `initializer`, except that functions marked with `reinitializer`
* cannot be nested. If one is invoked in the context of another, execution will revert.
*
* Note that versions can jump in increments greater than 1; this implies that if multiple reinitializers coexist in
* a contract, executing them in the right order is up to the developer or operator.
*
* WARNING: setting the version to 255 will prevent any future reinitialization.
*
* Emits an {Initialized} event.
*/
modifier reinitializer(uint8 version) {
require(!_initializing && _initialized < version, "Initializable: contract is already initialized");
_initialized = version;
_initializing = true;
_;
_initializing = false;
emit Initialized(version);
}
/**
* @dev Modifier to protect an initialization function so that it can only be invoked by functions with the
* {initializer} and {reinitializer} modifiers, directly or indirectly.
*/
modifier onlyInitializing() {
require(_initializing, "Initializable: contract is not initializing");
_;
}
/**
* @dev Locks the contract, preventing any future reinitialization. This cannot be part of an initializer call.
* Calling this in the constructor of a contract will prevent that contract from being initialized or reinitialized
* to any version. It is recommended to use this to lock implementation contracts that are designed to be called
* through proxies.
*
* Emits an {Initialized} event the first time it is successfully executed.
*/
function _disableInitializers() internal virtual {
require(!_initializing, "Initializable: contract is initializing");
if (_initialized < type(uint8).max) {
_initialized = type(uint8).max;
emit Initialized(type(uint8).max);
}
}
/**
* @dev Internal function that returns the initialized version. Returns `_initialized`
*/
function _getInitializedVersion() internal view returns (uint8) {
return _initialized;
}
/**
* @dev Internal function that returns the initialized version. Returns `_initializing`
*/
function _isInitializing() internal view returns (bool) {
return _initializing;
}
}
abstract contract Proxiable {
/// @dev Complying with EIP-1822: Universal Upgradeable Proxy Standard (UUPS)
/// @dev See https://eips.ethereum.org/EIPS/eip-1822.
function proxiableUUID() virtual external view returns (bytes32);
struct ProxiableSlot {
address implementation;
address proxy;
}
function __implementation() internal view returns (address) {
return __proxiable().implementation;
}
function __proxy() internal view returns (address) {
return __proxiable().proxy;
}
function __proxiable() internal pure returns (ProxiableSlot storage proxiable) {
assembly {
// bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1)
proxiable.slot := 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc
}
}
}
abstract contract Upgradeable is Initializable, Proxiable {
address internal immutable _BASE;
bytes32 internal immutable _CODEHASH;
bool internal immutable _UPGRADABLE;
modifier onlyDelegateCalls virtual {
require(
address(this) != _BASE,
"Upgradeable: not a delegate call"
);
_;
}
/// Emitted every time the contract gets upgraded.
/// @param from The address who ordered the upgrading. Namely, the WRB operator in "trustable" implementations.
/// @param baseAddr The address of the new implementation contract.
/// @param baseCodehash The EVM-codehash of the new implementation contract.
/// @param versionTag Ascii-encoded version literal with which the implementation deployer decided to tag it.
event Upgraded(
address indexed from,
address indexed baseAddr,
bytes32 indexed baseCodehash,
string versionTag
);
constructor (bool _isUpgradable) {
address _base = address(this);
bytes32 _codehash;
assembly {
_codehash := extcodehash(_base)
}
_BASE = _base;
_CODEHASH = _codehash;
_UPGRADABLE = _isUpgradable;
}
/// @dev Retrieves base contract. Differs from address(this) when called via delegate-proxy pattern.
function base() public view returns (address) {
return _BASE;
}
/// @dev Retrieves the immutable codehash of this contract, even if invoked as delegatecall.
function codehash() public view returns (bytes32) {
return _CODEHASH;
}
/// @dev Determines whether the logic of this contract is potentially upgradable.
function isUpgradable() public view returns (bool) {
return _UPGRADABLE;
}
/// @dev Tells whether provided address could eventually upgrade the contract.
function isUpgradableFrom(address from) virtual external view returns (bool);
/// @notice Re-initialize contract's storage context upon a new upgrade from a proxy.
/// @dev Must fail when trying to upgrade to same logic contract more than once.
function initialize(bytes memory) virtual external;
/// @dev Retrieves human-redable named version of current implementation.
function version() virtual public view returns (string memory);
}
/// @title WitnetProxy: upgradable delegate-proxy contract.
/// @author The Witnet Foundation.
contract WitnetProxy {
/// Event emitted every time the implementation gets updated.
event Upgraded(address indexed implementation);
/// Constructor with no params as to ease eventual support of Singleton pattern (i.e. ERC-2470).
constructor () {}
receive() virtual external payable {}
/// Payable fallback accepts delegating calls to payable functions.
fallback() external payable { /* solhint-disable no-complex-fallback */
address _implementation = implementation();
assembly { /* solhint-disable avoid-low-level-calls */
// Gas optimized delegate call to 'implementation' contract.
// Note: `msg.data`, `msg.sender` and `msg.value` will be passed over
// to actual implementation of `msg.sig` within `implementation` contract.
let ptr := mload(0x40)
calldatacopy(ptr, 0, calldatasize())
let result := delegatecall(gas(), _implementation, ptr, calldatasize(), 0, 0)
let size := returndatasize()
returndatacopy(ptr, 0, size)
switch result
case 0 {
// pass back revert message:
revert(ptr, size)
}
default {
// pass back same data as returned by 'implementation' contract:
return(ptr, size)
}
}
}
/// Returns proxy's current implementation address.
function implementation() public view returns (address) {
return __proxySlot().implementation;
}
/// Upgrades the `implementation` address.
/// @param _newImplementation New implementation address.
/// @param _initData Raw data with which new implementation will be initialized.
/// @return Returns whether new implementation would be further upgradable, or not.
function upgradeTo(address _newImplementation, bytes memory _initData)
public returns (bool)
{
// New implementation cannot be null:
require(_newImplementation != address(0), "WitnetProxy: null implementation");
address _oldImplementation = implementation();
if (_oldImplementation != address(0)) {
// New implementation address must differ from current one:
require(_newImplementation != _oldImplementation, "WitnetProxy: nothing to upgrade");
// Assert whether current implementation is intrinsically upgradable:
try Upgradeable(_oldImplementation).isUpgradable() returns (bool _isUpgradable) {
require(_isUpgradable, "WitnetProxy: not upgradable");
} catch {
revert("WitnetProxy: unable to check upgradability");
}
// Assert whether current implementation allows `msg.sender` to upgrade the proxy:
(bool _wasCalled, bytes memory _result) = _oldImplementation.delegatecall(
abi.encodeWithSignature(
"isUpgradableFrom(address)",
msg.sender
)
);
require(_wasCalled, "WitnetProxy: not compliant");
require(abi.decode(_result, (bool)), "WitnetProxy: not authorized");
require(
Upgradeable(_oldImplementation).proxiableUUID() == Upgradeable(_newImplementation).proxiableUUID(),
"WitnetProxy: proxiableUUIDs mismatch"
);
}
// Initialize new implementation within proxy-context storage:
(bool _wasInitialized,) = _newImplementation.delegatecall(
abi.encodeWithSignature(
"initialize(bytes)",
_initData
)
);
require(_wasInitialized, "WitnetProxy: unable to initialize");
// If all checks and initialization pass, update implementation address:
__proxySlot().implementation = _newImplementation;
emit Upgraded(_newImplementation);
// Asserts new implementation complies w/ minimal implementation of Upgradeable interface:
try Upgradeable(_newImplementation).isUpgradable() returns (bool _isUpgradable) {
return _isUpgradable;
}
catch {
revert ("WitnetProxy: not compliant");
}
}
/// @dev Complying with EIP-1967, retrieves storage struct containing proxy's current implementation address.
function __proxySlot() private pure returns (Proxiable.ProxiableSlot storage _slot) {
assembly {
// bytes32(uint256(keccak256('eip1967.proxy.implementation')) - 1)
_slot.slot := 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc
}
}
}

Contract ABI

[{"type":"constructor","stateMutability":"nonpayable","inputs":[]},{"type":"event","name":"Upgraded","inputs":[{"type":"address","name":"implementation","internalType":"address","indexed":true}],"anonymous":false},{"type":"fallback","stateMutability":"payable"},{"type":"function","stateMutability":"view","outputs":[{"type":"address","name":"","internalType":"address"}],"name":"implementation","inputs":[]},{"type":"function","stateMutability":"nonpayable","outputs":[{"type":"bool","name":"","internalType":"bool"}],"name":"upgradeTo","inputs":[{"type":"address","name":"_newImplementation","internalType":"address"},{"type":"bytes","name":"_initData","internalType":"bytes"}]},{"type":"receive","stateMutability":"payable"}]
            

Deployed ByteCode

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