pragma solidity 0.8.7;
// SPDX-License-Identifier: MIT
/**
* @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.
*/
contract Proxy {
address implementation_;
address public admin;
constructor(address impl) {
implementation_ = impl;
admin = msg.sender;
}
receive() external payable {}
function setImplementation(address newImpl) public {
require(msg.sender == admin);
implementation_ = newImpl;
}
function implementation() public view returns (address impl) {
impl = implementation_;
}
/**
* @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 virtual {
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 view returns (address) {
return 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() external payable virtual {
_delegate(_implementation());
}
}
{
"compilationTarget": {
"Proxy.sol": "Proxy"
},
"evmVersion": "london",
"libraries": {},
"metadata": {
"bytecodeHash": "ipfs"
},
"optimizer": {
"enabled": true,
"runs": 200
},
"remappings": []
}
[{"inputs":[{"internalType":"address","name":"impl","type":"address"}],"stateMutability":"nonpayable","type":"constructor"},{"stateMutability":"payable","type":"fallback"},{"inputs":[],"name":"admin","outputs":[{"internalType":"address","name":"","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[],"name":"implementation","outputs":[{"internalType":"address","name":"impl","type":"address"}],"stateMutability":"view","type":"function"},{"inputs":[{"internalType":"address","name":"newImpl","type":"address"}],"name":"setImplementation","outputs":[],"stateMutability":"nonpayable","type":"function"},{"stateMutability":"payable","type":"receive"}]