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Proxy.sol
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Proxy.sol
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// SPDX-License-Identifier: MIT
// NOTE: These contracts have a critical bug.
// DO NOT USE THIS IN PRODUCTION
pragma solidity 0.8.10;
/// A proxy contract inspired by
/// https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/contracts/proxy/Proxy.sol
///
/// Only the owner can call the contract, where owner is an immutable variable set during the
/// construction.
///
/// The implementation will be set to a deployment of `Implementation.sol`.
contract Proxy {
address immutable public owner;
address public implementation;
constructor(address _implementation, address _owner) {
owner = _owner;
implementation = _implementation;
}
fallback() external payable {
require(msg.sender == owner);
address _implementation = implementation;
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 space at memory position 0.
calldatacopy(0, 0, calldatasize())
// delegatecall the implementation.
// out and outsize are 0 because we don't know the size yet.
let success := delegatecall(gas(), _implementation, 0, calldatasize(), 0, 0)
// copy the returned data.
returndatacopy(0, 0, returndatasize())
switch success
// delegatecall returns 0 on error.
case 0 {
revert(0, returndatasize())
}
default {
return(0, returndatasize())
}
}
}
receive() external payable {
}
}