代理合约Motorbike

源码：

// SPDX-License-Identifier: MIT

pragma solidity <0.7.0;

import "@openzeppelin/contracts/utils/Address.sol";
import "@openzeppelin/contracts/proxy/Initializable.sol";

contract Motorbike {
    // keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;
    
    struct AddressSlot {
        address value;
    }
    
    // Initializes the upgradeable proxy with an initial implementation specified by `_logic`.
    constructor(address _logic) public {
        require(Address.isContract(_logic), "ERC1967: new implementation is not a contract");
        _getAddressSlot(_IMPLEMENTATION_SLOT).value = _logic;
        (bool success,) = _logic.delegatecall(
            abi.encodeWithSignature("initialize()")
        );
        require(success, "Call failed");
    }

    // Delegates the current call to `implementation`.
    function _delegate(address implementation) internal virtual {
        // solhint-disable-next-line no-inline-assembly
        assembly {
            calldatacopy(0, 0, calldatasize())
            let result := delegatecall(gas(), implementation, 0, calldatasize(), 0, 0)
            returndatacopy(0, 0, returndatasize())
            switch result
            case 0 { revert(0, returndatasize()) }
            default { return(0, returndatasize()) }
        }
    }

    // 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(_getAddressSlot(_IMPLEMENTATION_SLOT).value);
    }

    // Returns an `AddressSlot` with member `value` located at `slot`.
    function _getAddressSlot(bytes32 slot) internal pure returns (AddressSlot storage r) {
        assembly {
            r_slot := slot
        }
    }
}

contract Engine is Initializable {
    // keccak-256 hash of "eip1967.proxy.implementation" subtracted by 1
    bytes32 internal constant _IMPLEMENTATION_SLOT = 0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc;

    address public upgrader;
    uint256 public horsePower;

    struct AddressSlot {
        address value;
    }

    function initialize() external initializer {
        horsePower = 1000;
        upgrader = msg.sender;
    }

    // Upgrade the implementation of the proxy to `newImplementation`
    // subsequently execute the function call
    function upgradeToAndCall(address newImplementation, bytes memory data) external payable {
        _authorizeUpgrade();
        _upgradeToAndCall(newImplementation, data);
    }

    // Restrict to upgrader role
    function _authorizeUpgrade() internal view {
        require(msg.sender == upgrader, "Can't upgrade");
    }

    // Perform implementation upgrade with security checks for UUPS proxies, and additional setup call.
    function _upgradeToAndCall(
        address newImplementation,
        bytes memory data
    ) internal {
        // Initial upgrade and setup call
        _setImplementation(newImplementation);
        if (data.length > 0) {
            (bool success,) = newImplementation.delegatecall(data);
            require(success, "Call failed");
        }
    }
    
    // Stores a new address in the EIP1967 implementation slot.
    function _setImplementation(address newImplementation) private {
        require(Address.isContract(newImplementation), "ERC1967: new implementation is not a contract");
        
        AddressSlot storage r;
        assembly {
            r_slot := _IMPLEMENTATION_SLOT
        }
        r.value = newImplementation;
    }
}

分析：

这关的条件是让我们销毁Engine，很自然联想到selfdestruct.
那么我们首先得找到engine合约得地址，在两个合约里都定义了被代理合约Engine地址存储的槽编号，我们直接去控制台查找。

await web3.eth.getStorageAt(contract.address,'0x360894a13ba1a3210667c828492db98dca3e2076cc3735a920a3ca505d382bbc')

'0x7c9bb0823d0e48ec3e553c3bac4fbe2de384861f'就是engine的地址，修改engine时需要保证player的角色为upgrader，我们看一看Engine的存储状态，其实都是为空，其原因是Engine只作为函数的提供者，具体变量状态的存储则是通过Motorbike执行。此时Engine本身就是未经初始过的新合约，所以我们只需要调一下initialize完成初始化。

selector =web3.utils.keccak256("initialize()").slice(0,10) await web3.eth.sendTransaction({from:player,to:'0x7c9bb0823d0e48ec3e553c3bac4fbe2de384861f',data:selector})

upgrader已经变成我们自己的地址了，我们可以调用upgradeToAndCall完成业务合约的修改

我们要构建调用合约时的data一般有几种方法。

我们已经得到了destuct的data数据，我们现在要将其作为bytes注入到upgradeToAndCall中去

调用，进行自毁

await web3.eth.sendTransaction({from:player,to:'0x7c9bb0823d0e48ec3e553c3bac4fbe2de384861f',data:data2})